Thermal-stress analysis for a wood composite blade

NASA Technical Reports Server (NTRS)

Fu, K. C.; Harb, A.

1984-01-01

A thermal-stress analysis of a wind turbine blade made of wood composite material is reported. First, the governing partial differential equation on heat conduction is derived, then, a finite element procedure using variational approach is developed for the solution of the governing equation. Thus, the temperature distribution throughout the blade is determined. Next, based on the temperature distribution, a finite element procedure using potential energy approach is applied to determine the thermal-stress distribution. A set of results is obtained through the use of a computer, which is considered to be satisfactory. All computer programs are contained in the report.

Structural Tailoring of Advanced Turboprops (STAT)

NASA Technical Reports Server (NTRS)

Brown, Kenneth W.

1988-01-01

This interim report describes the progress achieved in the structural Tailoring of Advanced Turboprops (STAT) program which was developed to perform numerical optimizations on highly swept propfan blades. The optimization procedure seeks to minimize an objective function, defined as either direct operating cost or aeroelastic differences between a blade and its scaled model, by tuning internal and external geometry variables that must satisfy realistic blade design constraints. This report provides a detailed description of the input, optimization procedures, approximate analyses and refined analyses, as well as validation test cases for the STAT program. In addition, conclusions and recommendations are summarized.

Recent advances in integrated multidisciplinary optimization of rotorcraft

NASA Technical Reports Server (NTRS)

Adelman, Howard M.; Walsh, Joanne L.; Pritchard, Jocelyn I.

1992-01-01

A joint activity involving NASA and Army researchers at NASA LaRC to develop optimization procedures to improve the rotor blade design process by integrating appropriate disciplines and accounting for all of the important interactions among the disciplines is described. The disciplines involved include rotor aerodynamics, rotor dynamics, rotor structures, airframe dynamics, and acoustics. The work is focused on combining these five key disciplines in an optimization procedure capable of designing a rotor system to satisfy multidisciplinary design requirements. Fundamental to the plan is a three-phased approach. In phase 1, the disciplines of blade dynamics, blade aerodynamics, and blade structure are closely coupled while acoustics and airframe dynamics are decoupled and are accounted for as effective constraints on the design for the first three disciplines. In phase 2, acoustics is integrated with the first three disciplines. Finally, in phase 3, airframe dynamics is integrated with the other four disciplines. Representative results from work performed to date are described. These include optimal placement of tuning masses for reduction of blade vibratory shear forces, integrated aerodynamic/dynamic optimization, and integrated aerodynamic/dynamic/structural optimization. Examples of validating procedures are described.

Recent advances in multidisciplinary optimization of rotorcraft

NASA Technical Reports Server (NTRS)

Adelman, Howard M.; Walsh, Joanne L.; Pritchard, Jocelyn I.

1992-01-01

A joint activity involving NASA and Army researchers at NASA LaRC to develop optimization procedures to improve the rotor blade design process by integrating appropriate disciplines and accounting for all of the important interactions among the disciplines is described. The disciplines involved include rotor aerodynamics, rotor dynamics, rotor structures, airframe dynamics, and acoustics. The work is focused on combining these five key disciplines in an optimization procedure capable of designing a rotor system to satisfy multidisciplinary design requirements. Fundamental to the plan is a three-phased approach. In phase 1, the disciplines of blade dynamics, blade aerodynamics, and blade structure are closely coupled while acoustics and airframe dynamics are decoupled and are accounted for as effective constraints on the design for the first three disciplines. In phase 2, acoustics is integrated with the first three disciplines. Finally, in phase 3, airframe dynamics is integrated with the other four disciplines. Representative results from work performed to date are described. These include optimal placement of tuning masses for reduction of blade vibratory shear forces, integrated aerodynamic/dynamic optimization, and integrated aerodynamic/dynamic/structural optimization. Examples of validating procedures are described.

Transonic Axial Splittered Rotor Tandem Stator Stage

DTIC Science & Technology

2016-12-01

CODE 13. ABSTRACT (maximum 200 words) Development of a procedure to model the hot shape of a rotor blade and a comparison analysis of the transonic...fluid-structure interaction. Rotational forces as well as gas loading forces were observed as an influence on blade deformation. Utilizing the...Turbomachinery, splittered rotor, tandem stator, transonic compressor, blade deformation, fluid-structure interaction 15. NUMBER OF PAGES 87 16. PRICE

The Sharpness of Blades Used in Dermatologic Surgery.

PubMed

Awadalla, Farah; Hexsel, Camile; Goldberg, Leonard H

2016-01-01

There are numerous blades available for use in dermatologic procedures. There are different advantages that are inhere.nt to different blades due to their shape and size. One aspect of the blade that is instrumental to its performance, but is not objectively defined, is sharpness. This information could be useful when choosing a blade for a particular procedure. This study aims to objectively define the sharpness of blades used in dermatologic surgery. The Sharpness Tester (Cutlery and Allied Trades Research Association, Sheffield, UK) was used to test the force in Newtons a blade requires to cut through a silicone cylinder. New blades were used to determine a standard for the sharpness of new blades. Blades used for surgery were tested to determine the sharpness after use. The sharpest blade is the double-edged razor blade (0.395 N) followed by the dermablade (0.46 N), plastic handled #15 (0.541 N), #15c (0.575 N), #10 (0.647 N), and the #15 blade (0.664 N). The sharpness of a blade is an important factor in its ability to perform a task and should be taken into account when choosing a particular blade for a particular procedure.

Multidisciplinary Optimization of Tilt Rotor Blades Using Comprehensive Composite Modeling Technique

NASA Technical Reports Server (NTRS)

Chattopadhyay, Aditi; McCarthy, Thomas R.; Rajadas, John N.

1997-01-01

An optimization procedure is developed for addressing the design of composite tilt rotor blades. A comprehensive technique, based on a higher-order laminate theory, is developed for the analysis of the thick composite load-carrying sections, modeled as box beams, in the blade. The theory, which is based on a refined displacement field, is a three-dimensional model which approximates the elasticity solution so that the beam cross-sectional properties are not reduced to one-dimensional beam parameters. Both inplane and out-of-plane warping are included automatically in the formulation. The model can accurately capture the transverse shear stresses through the thickness of each wall while satisfying stress free boundary conditions on the inner and outer surfaces of the beam. The aerodynamic loads on the blade are calculated using the classical blade element momentum theory. Analytical expressions for the lift and drag are obtained based on the blade planform with corrections for the high lift capability of rotor blades. The aerodynamic analysis is coupled with the structural model to formulate the complete coupled equations of motion for aeroelastic analyses. Finally, a multidisciplinary optimization procedure is developed to improve the aerodynamic, structural and aeroelastic performance of the tilt rotor aircraft. The objective functions include the figure of merit in hover and the high speed cruise propulsive efficiency. Structural, aerodynamic and aeroelastic stability criteria are imposed as constraints on the problem. The Kreisselmeier-Steinhauser function is used to formulate the multiobjective function problem. The search direction is determined by the Broyden-Fletcher-Goldfarb-Shanno algorithm. The optimum results are compared with the baseline values and show significant improvements in the overall performance of the tilt rotor blade.

A methodology to guide the selection of composite materials in a wind turbine rotor blade design process

NASA Astrophysics Data System (ADS)

Bortolotti, P.; Adolphs, G.; Bottasso, C. L.

2016-09-01

This work is concerned with the development of an optimization methodology for the composite materials used in wind turbine blades. Goal of the approach is to guide designers in the selection of the different materials of the blade, while providing indications to composite manufacturers on optimal trade-offs between mechanical properties and material costs. The method works by using a parametric material model, and including its free parameters amongst the design variables of a multi-disciplinary wind turbine optimization procedure. The proposed method is tested on the structural redesign of a conceptual 10 MW wind turbine blade, its spar caps and shell skin laminates being subjected to optimization. The procedure identifies a blade optimum for a new spar cap laminate characterized by a higher longitudinal Young's modulus and higher cost than the initial one, which however in turn induce both cost and mass savings in the blade. In terms of shell skin, the adoption of a laminate with intermediate properties between a bi-axial one and a tri-axial one also leads to slight structural improvements.

General approach and scope. [rotor blade design optimization

NASA Technical Reports Server (NTRS)

Adelman, Howard M.; Mantay, Wayne R.

1989-01-01

This paper describes a joint activity involving NASA and Army researchers at the NASA Langley Research Center to develop optimization procedures aimed at improving the rotor blade design process by integrating appropriate disciplines and accounting for all of the important interactions among the disciplines. The disciplines involved include rotor aerodynamics, rotor dynamics, rotor structures, airframe dynamics, and acoustics. The work is focused on combining these five key disciplines in an optimization procedure capable of designing a rotor system to satisfy multidisciplinary design requirements. Fundamental to the plan is a three-phased approach. In phase 1, the disciplines of blade dynamics, blade aerodynamics, and blade structure will be closely coupled, while acoustics and airframe dynamics will be decoupled and be accounted for as effective constraints on the design for the first three disciplines. In phase 2, acoustics is to be integrated with the first three disciplines. Finally, in phase 3, airframe dynamics will be fully integrated with the other four disciplines. This paper deals with details of the phase 1 approach and includes details of the optimization formulation, design variables, constraints, and objective function, as well as details of discipline interactions, analysis methods, and methods for validating the procedure.

Blade row interaction effects on flutter and forced response

NASA Technical Reports Server (NTRS)

Buffum, Daniel H.

1993-01-01

In the flutter or forced response analysis of a turbomachine blade row, the blade row in question is commonly treated as if it is isolated from the neigboring blade rows. Disturbances created by vibrating blades are then free to propagate away from this blade row without being disturbed. In reality, neighboring blade rows will reflect some portion of this wave energy back toward the vibrating blades, causing additional unsteady forces on them. It is of fundamental importance to determine whether or not these reflected waves can have a significant effect on the aeroelastic stability or forced response of a blade row. Therefore, a procedure to calculate intra-blade-row unsteady aerodynamic interactions was developed which relies upon results available from isolated blade row unsteady aerodynamic analyses. In addition, an unsteady aerodynamic influence coefficient technique is used to obtain a model for the vibratory response in which the neighboring blade rows are also flexible. The flutter analysis shows that interaction effects can be destabilizing, and the forced response analysis shows that interaction effects can result in a significant increase in the resonant response of a blade row.

Optimizing tuning masses for helicopter rotor blade vibration reduction including computed airloads and comparison with test data

NASA Technical Reports Server (NTRS)

Pritchard, Jocelyn I.; Adelman, Howard M.; Walsh, Joanne L.; Wilbur, Matthew L.

1992-01-01

The development and validation of an optimization procedure to systematically place tuning masses along a rotor blade span to minimize vibratory loads are described. The masses and their corresponding locations are the design variables that are manipulated to reduce the harmonics of hub shear for a four-bladed rotor system without adding a large mass penalty. The procedure incorporates a comprehensive helicopter analysis to calculate the airloads. Predicting changes in airloads due to changes in design variables is an important feature of this research. The procedure was applied to a one-sixth, Mach-scaled rotor blade model to place three masses and then again to place six masses. In both cases the added mass was able to achieve significant reductions in the hub shear. In addition, the procedure was applied to place a single mass of fixed value on a blade model to reduce the hub shear for three flight conditions. The analytical results were compared to experimental data from a wind tunnel test performed in the Langley Transonic Dynamics Tunnel. The correlation of the mass location was good and the trend of the mass location with respect to flight speed was predicted fairly well. However, it was noted that the analysis was not entirely successful at predicting the absolute magnitudes of the fixed system loads.

An unsteady Euler scheme for the analysis of ducted propellers

NASA Technical Reports Server (NTRS)

Srivastava, R.

1992-01-01

An efficient unsteady solution procedure has been developed for analyzing inviscid unsteady flow past ducted propeller configurations. This scheme is first order accurate in time and second order accurate in space. The solution procedure has been applied to a ducted propeller consisting of an 8-bladed SR7 propeller with a duct of NACA 0003 airfoil cross section around it, operating in a steady axisymmetric flowfield. The variation of elemental blade loading with radius, compares well with other published numerical results.

Structural tailoring of advanced turboprops

NASA Technical Reports Server (NTRS)

Brown, K. W.; Hopkins, Dale A.

1988-01-01

The Structural Tailoring of Advanced Turboprops (STAT) computer program was developed to perform numerical optimization on highly swept propfan blades. The optimization procedure seeks to minimize an objective function defined as either: (1) direct operating cost of full scale blade or, (2) aeroelastic differences between a blade and its scaled model, by tuning internal and external geometry variables that must satisfy realistic blade design constraints. The STAT analysis system includes an aerodynamic efficiency evaluation, a finite element stress and vibration analysis, an acoustic analysis, a flutter analysis, and a once-per-revolution forced response life prediction capability. STAT includes all relevant propfan design constraints.

Summary of Full-Scale Blade Displacement Measurements of the UH- 60A Airloads Rotor

NASA Technical Reports Server (NTRS)

Abrego, Anita I.; Meyn, Larry; Burner, Alpheus W.; Barrows, Danny A.

2016-01-01

Blade displacement measurements using multi-camera photogrammetry techniques were acquired for a full-scale UH-60A rotor, tested in the National Full-Scale Aerodynamic Complex 40-Foot by 80-Foot Wind Tunnel. The measurements, acquired over the full rotor azimuth, encompass a range of test conditions that include advance ratios from 0.15 to 1.0, thrust coefficient to rotor solidity ratios from 0.01 to 0.13, and rotor shaft angles from -10.0 to 8.0 degrees. The objective was to measure the blade displacements and deformations of the four rotor blades and provide a benchmark blade displacement database to be utilized in the development and validation of rotorcraft prediction techniques. An overview of the blade displacement measurement methodology, system development, and data analysis techniques are presented. Sample results based on the final set of camera calibrations, data reduction procedures and estimated corrections that account for registration errors due to blade elasticity are shown. Differences in blade root pitch, flap and lag between the previously reported results and the current results are small. However, even small changes in estimated root flap and pitch can lead to significant differences in the blade elasticity values.

Multidisciplinary Design Optimization for Glass-Fiber Epoxy-Matrix Composite 5 MW Horizontal-Axis Wind-Turbine Blades

NASA Astrophysics Data System (ADS)

Grujicic, M.; Arakere, G.; Pandurangan, B.; Sellappan, V.; Vallejo, A.; Ozen, M.

2010-11-01

A multi-disciplinary design-optimization procedure has been introduced and used for the development of cost-effective glass-fiber reinforced epoxy-matrix composite 5 MW horizontal-axis wind-turbine (HAWT) blades. The turbine-blade cost-effectiveness has been defined using the cost of energy (CoE), i.e., a ratio of the three-blade HAWT rotor development/fabrication cost and the associated annual energy production. To assess the annual energy production as a function of the blade design and operating conditions, an aerodynamics-based computational analysis had to be employed. As far as the turbine blade cost is concerned, it is assessed for a given aerodynamic design by separately computing the blade mass and the associated blade-mass/size-dependent production cost. For each aerodynamic design analyzed, a structural finite element-based and a post-processing life-cycle assessment analyses were employed in order to determine a minimal blade mass which ensures that the functional requirements pertaining to the quasi-static strength of the blade, fatigue-controlled blade durability and blade stiffness are satisfied. To determine the turbine-blade production cost (for the currently prevailing fabrication process, the wet lay-up) available data regarding the industry manufacturing experience were combined with the attendant blade mass, surface area, and the duration of the assumed production run. The work clearly revealed the challenges associated with simultaneously satisfying the strength, durability and stiffness requirements while maintaining a high level of wind-energy capture efficiency and a lower production cost.

Structural Tailoring of Advanced Turboprops (STAT). Theoretical manual

NASA Technical Reports Server (NTRS)

Brown, K. W.

1992-01-01

This manual describes the theories in the Structural Tailoring of Advanced Turboprops (STAT) computer program, which was developed to perform numerical optimizations on highly swept propfan blades. The optimization procedure seeks to minimize an objective function, defined as either direct operating cost or aeroelastic differences between a blade and its scaled model, by tuning internal and external geometry variables that must satisfy realistic blade design constraints. The STAT analyses include an aerodynamic efficiency evaluation, a finite element stress and vibration analysis, an acoustic analysis, a flutter analysis, and a once-per-revolution (1-p) forced response life prediction capability. The STAT constraints include blade stresses, blade resonances, flutter, tip displacements, and a 1-P forced response life fraction. The STAT variables include all blade internal and external geometry parameters needed to define a composite material blade. The STAT objective function is dependent upon a blade baseline definition which the user supplies to describe a current blade design for cost optimization or for the tailoring of an aeroelastic scale model.

Structural Tailoring of Advanced Turboprops (STAT). Theoretical manual

NASA Astrophysics Data System (ADS)

Brown, K. W.

1992-10-01

This manual describes the theories in the Structural Tailoring of Advanced Turboprops (STAT) computer program, which was developed to perform numerical optimizations on highly swept propfan blades. The optimization procedure seeks to minimize an objective function, defined as either direct operating cost or aeroelastic differences between a blade and its scaled model, by tuning internal and external geometry variables that must satisfy realistic blade design constraints. The STAT analyses include an aerodynamic efficiency evaluation, a finite element stress and vibration analysis, an acoustic analysis, a flutter analysis, and a once-per-revolution (1-p) forced response life prediction capability. The STAT constraints include blade stresses, blade resonances, flutter, tip displacements, and a 1-P forced response life fraction. The STAT variables include all blade internal and external geometry parameters needed to define a composite material blade. The STAT objective function is dependent upon a blade baseline definition which the user supplies to describe a current blade design for cost optimization or for the tailoring of an aeroelastic scale model.

Experimental Investigation of Air-Cooled Turbine Blades in Turbojet Engine. 7: Rotor-Blade Fabrication Procedures

NASA Technical Reports Server (NTRS)

Long, Roger A.; Esgar, Jack B.

1951-01-01

An experimental investigation was conducted to determine the cooling effectiveness of a wide variety of air-cooled turbine-blade configurations. The blades, which were tested in the turbine of a - commercial turbojet engine that was modified for this investigation by replacing two of the original blades with air-cooled blades located diametrically opposite each other, are untwisted, have no aerodynamic taper, and have essentially the same external profile. The cooling-passage configuration is different for each blade, however. The fabrication procedures were varied and often unique. The blades were fabricated using methods most suitable for obtaining a small number of blades for use in the cooling investigations and therefore not all the fabrication procedures would be directly applicable to production processes, although some of the ideas and steps might be useful. Blade shells were obtained by both casting and forming. The cast shells were either welded to the blade base or cast integrally with the base. The formed shells were attached to the base by a brazing and two welding methods. Additional surface area was supplied in the coolant passages by the addition of fins or tubes that were S-brazed. to the shell. A number of blades with special leading- and trailing-edge designs that provided added cooling to these areas were fabricated. The cooling effectiveness and purposes of the various blade configurations are discussed briefly.

Application of additive laser technologies in the gas turbine blades design process

NASA Astrophysics Data System (ADS)

Shevchenko, I. V.; Rogalev, A. N.; Osipov, S. K.; Bychkov, N. M.; Komarov, I. I.

2017-11-01

An emergence of modern innovative technologies requires delivering new and modernization existing design and production processes. It is especially relevant for designing the high-temperature turbines of gas turbine engines, development of which is characterized by a transition to higher parameters of working medium in order to improve their efficient performance. A design technique for gas turbine blades based on predictive verification of thermal and hydraulic models of their cooling systems by testing of a blade prototype fabricated using the selective laser melting technology was presented in this article. Technique was proven at the time of development of the first stage blade cooling system for the high-pressure turbine. An experimental procedure for verification of a thermal model of the blades with convective cooling systems based on the comparison of heat-flux density obtained from the numerical simulation data and results of tests in a liquid-metal thermostat was developed. The techniques makes it possible to obtain an experimentally tested blade version and to exclude its experimental adjustment after the start of mass production.

Aeroelastic Analysis of Helicopter Rotor Blades Incorporating Anisotropic Piezoelectric Twist Actuation

NASA Technical Reports Server (NTRS)

Wilkie, W. Keats; Belvin, W. Keith; Park, K. C.

1996-01-01

A simple aeroelastic analysis of a helicopter rotor blade incorporating embedded piezoelectric fiber composite, interdigitated electrode blade twist actuators is described. The analysis consists of a linear torsion and flapwise bending model coupled with a nonlinear ONERA based unsteady aerodynamics model. A modified Galerkin procedure is performed upon the rotor blade partial differential equations of motion to develop a system of ordinary differential equations suitable for dynamics simulation using numerical integration. The twist actuation responses for three conceptual fullscale blade designs with realistic constraints on blade mass are numerically evaluated using the analysis. Numerical results indicate that useful amplitudes of nonresonant elastic twist, on the order of one to two degrees, are achievable under one-g hovering flight conditions for interdigitated electrode poling configurations. Twist actuation for the interdigitated electrode blades is also compared with the twist actuation of a conventionally poled piezoelectric fiber composite blade. Elastic twist produced using the interdigitated electrode actuators was found to be four to five times larger than that obtained with the conventionally poled actuators.

An aeroelastic analysis of helicopter rotor blades incorporating piezoelectric fiber composite twist actuation

NASA Technical Reports Server (NTRS)

Wilkie, W. Keats; Park, K. C.

1996-01-01

A simple aeroelastic analysis of a helicopter rotor blade incorporating embedded piezoelectric fiber composite, interdigitated electrode blade twist actuators is described. The analysis consist of a linear torsion and flapwise bending model coupled with a nonlinear ONERA based unsteady aerodynamics model. A modified Galerkin procedure is performed upon the rotor blade partial differential equations of motion to develop a system of ordinary differential equations suitable for numerical integration. The twist actuation responses for three conceptual full-scale blade designs with realistic constraints on blade mass are numerically evaluated using the analysis. Numerical results indicate that useful amplitudes of nonresonant elastic twist, on the order of one to two degrees, are achievable under one-g hovering flight conditions for interdigitated electrode poling configurations. Twist actuation for the interdigitated electrode blades is also compared with the twist actuation of a conventionally poled piezoelectric fiber composite blade. Elastic twist produced using the interdigitated electrode actuators was found to be four to five times larger than that obtained with the conventionally poled actuators.

Task III: Development of an Effective Computational Methodology for Body Force Representation of High-speed Rotor 37

NASA Technical Reports Server (NTRS)

Tan, Choon-Sooi; Suder, Kenneth (Technical Monitor)

2003-01-01

A framework for an effective computational methodology for characterizing the stability and the impact of distortion in high-speed multi-stage compressor is being developed. The methodology consists of using a few isolated-blade row Navier-Stokes solutions for each blade row to construct a body force database. The purpose of the body force database is to replace each blade row in a multi-stage compressor by a body force distribution to produce same pressure rise and flow turning. To do this, each body force database is generated in such a way that it can respond to the changes in local flow conditions. Once the database is generated, no hrther Navier-Stokes computations are necessary. The process is repeated for every blade row in the multi-stage compressor. The body forces are then embedded as source terms in an Euler solver. The method is developed to have the capability to compute the performance in a flow that has radial as well as circumferential non-uniformity with a length scale larger than a blade pitch; thus it can potentially be used to characterize the stability of a compressor under design. It is these two latter features as well as the accompanying procedure to obtain the body force representation that distinguish the present methodology from the streamline curvature method. The overall computational procedures have been developed. A dimensional analysis was carried out to determine the local flow conditions for parameterizing the magnitudes of the local body force representation of blade rows. An Euler solver was modified to embed the body forces as source terms. The results from the dimensional analysis show that the body forces can be parameterized in terms of the two relative flow angles, the relative Mach number, and the Reynolds number. For flow in a high-speed transonic blade row, they can be parameterized in terms of the local relative Mach number alone.

Fully integrated aerodynamic/dynamic optimization of helicopter rotor blades

NASA Technical Reports Server (NTRS)

Walsh, Joanne L.; Lamarsh, William J., II; Adelman, Howard M.

1992-01-01

This paper describes a fully integrated aerodynamic/dynamic optimization procedure for helicopter rotor blades. The procedure combines performance and dynamics analyses with a general purpose optimizer. The procedure minimizes a linear combination of power required (in hover, forward flight, and maneuver) and vibratory hub shear. The design variables include pretwist, taper initiation, taper ratio, root chord, blade stiffnesses, tuning masses, and tuning mass locations. Aerodynamic constraints consist of limits on power required in hover, forward flight and maneuver; airfoil section stall; drag divergence Mach number; minimum tip chord; and trim. Dynamic constraints are on frequencies, minimum autorotational inertia, and maximum blade weight. The procedure is demonstrated for two cases. In the first case the objective function involves power required (in hover, forward flight, and maneuver) and dynamics. The second case involves only hover power and dynamics. The designs from the integrated procedure are compared with designs from a sequential optimization approach in which the blade is first optimized for performance and then for dynamics. In both cases, the integrated approach is superior.

Fully integrated aerodynamic/dynamic optimization of helicopter rotor blades

NASA Technical Reports Server (NTRS)

Walsh, Joanne L.; Lamarsh, William J., II; Adelman, Howard M.

1992-01-01

A fully integrated aerodynamic/dynamic optimization procedure is described for helicopter rotor blades. The procedure combines performance and dynamic analyses with a general purpose optimizer. The procedure minimizes a linear combination of power required (in hover, forward flight, and maneuver) and vibratory hub shear. The design variables include pretwist, taper initiation, taper ratio, root chord, blade stiffnesses, tuning masses, and tuning mass locations. Aerodynamic constraints consist of limits on power required in hover, forward flight and maneuvers; airfoil section stall; drag divergence Mach number; minimum tip chord; and trim. Dynamic constraints are on frequencies, minimum autorotational inertia, and maximum blade weight. The procedure is demonstrated for two cases. In the first case, the objective function involves power required (in hover, forward flight and maneuver) and dynamics. The second case involves only hover power and dynamics. The designs from the integrated procedure are compared with designs from a sequential optimization approach in which the blade is first optimized for performance and then for dynamics. In both cases, the integrated approach is superior.

The use of optimization techniques to design controlled diffusion compressor blading

NASA Technical Reports Server (NTRS)

Sanger, N. L.

1982-01-01

A method for automating compressor blade design using numerical optimization, and applied to the design of a controlled diffusion stator blade row is presented. A general purpose optimization procedure is employed, based on conjugate directions for locally unconstrained problems and on feasible directions for locally constrained problems. Coupled to the optimizer is an analysis package consisting of three analysis programs which calculate blade geometry, inviscid flow, and blade surface boundary layers. The optimizing concepts and selection of design objective and constraints are described. The procedure for automating the design of a two dimensional blade section is discussed, and design results are presented.

Comprehensive analysis of helicopters with bearingless rotors

NASA Technical Reports Server (NTRS)

Murthy, V. R.

1988-01-01

A modified Galerkin method is developed to analyze the dynamic problems of multiple-load-path bearingless rotor blades. The development and selection of functions are quite parallel to CAMRAD procedures, greatly facilitating the implementation of the method into the CAMRAD program. A software is developed implementing the modified Galerkin method to determine free vibration characteristics of multiple-load-path rotor blades undergoing coupled flapwise bending, chordwise bending, twisting, and extensional motions. Results are in the process of being obtained by debugging the software.

Dynamic analysis method for prevention of failure in the first-stage low-pressure turbine blade with two-finger root

NASA Astrophysics Data System (ADS)

Park, Jung-Yong; Jung, Yong-Keun; Park, Jong-Jin; Kang, Yong-Ho

2002-05-01

Failures of turbine blades are identified as the leading causes of unplanned outages for steam turbine. Accidents of low-pressure turbine blade occupied more than 70 percent in turbine components. Therefore, the prevention of failures for low pressure turbine blades is certainly needed. The procedure is illustrated by the case study. This procedure is used to guide, and support the plant manager's decisions to avoid a costly, unplanned outage. In this study, we are trying to find factors of failures in LP turbine blade and to make three steps to approach the solution of blade failure. First step is to measure natural frequency in mockup test and to compare it with nozzle passing frequency. Second step is to use FEM and to calculate the natural frequencies of 7 blades and 10 blades per group in BLADE code. Third step is to find natural frequencies of grouped blade off the nozzle passing frequency.

Experimental and analytical investigation of fan flow interaction with downstream struts

NASA Technical Reports Server (NTRS)

Olsen, T. L.; Ng, W. F.; Obrien, W. F., Jr.

1985-01-01

An investigation which was designed to provide insight into the fundamental aspects of fan rotor-downstream strut interaction was undertaken. High response, miniature pressure transducers were embedded in the rotor blades of an experimental fan rig. Five downstream struts were placed at several downstream locations in the discharge flow annulus of the single-stage machine. Significant interaction of the rotor blade surface pressures with the flow disturbance produced by the downstream struts was measured. Several numerical procedures for calculating the quasi-steady rotor response due to downstream flow obstructions were developed. A preliminary comparison of experimental and calculated fluctuating blade pressures on the rotor blades shows general agreement between the experimental and calculated values.

Comprehensive Forced Response Analysis of J2X Turbine Bladed-Discs with 36- Degree Variation in CFD Loading

NASA Technical Reports Server (NTRS)

Elrod, David; Christensen, Eric; Brown, Andrew

2011-01-01

At NASA/MSFC, Structural Dynamics personnel continue to perform advanced analysis for the turbomachinery in the J2X Rocket Engine, which is under consideration for the new Space Launch System. One of the most challenging analyses in the program is predicting turbine blade structural capability. Resonance was predicted by modal analysis, so comprehensive forced response analyses using high fidelity cyclic symmetric finite element models were initiated as required. Analysis methodologies up to this point have assumed the flow field could be fully described by a sector, so the loading on every blade would be identical as it travelled through it. However, in the J2X the CFD flow field varied over the 360 deg of a revolution because of the flow speeds and tortuous axial path. MSFC therefore developed a complex procedure using Nastran Dmap's and Matlab scripts to apply this circumferentially varying loading onto the cyclically symmetric structural models to produce accurate dynamic stresses for every blade on the disk. This procedure is coupled with static, spin, and thermal loading to produce high cycle fatigue safety factors resulting in much more accurate analytical assessments of the blades.

78 FR 69987 - Airworthiness Directives; Erickson Air-Crane Incorporated Helicopters (Type Certificate...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-22

... to require recurring checks of the Blade Inspection Method (BIM) indicator on each blade to determine whether the BIM indicator is signifying that the blade pressure may have been compromised by a blade crack... check procedures for BIM blades installed on the Model S-64E and S-64F helicopters. Several blade spars...

A Unified Development of Basis Reduction Methods for Rotor Blade Analysis

NASA Technical Reports Server (NTRS)

Ruzicka, Gene C.; Hodges, Dewey H.; Rutkowski, Michael (Technical Monitor)

2001-01-01

The axial foreshortening effect plays a key role in rotor blade dynamics, but approximating it accurately in reduced basis models has long posed a difficult problem for analysts. Recently, though, several methods have been shown to be effective in obtaining accurate,reduced basis models for rotor blades. These methods are the axial elongation method,the mixed finite element method, and the nonlinear normal mode method. The main objective of this paper is to demonstrate the close relationships among these methods, which are seemingly disparate at first glance. First, the difficulties inherent in obtaining reduced basis models of rotor blades are illustrated by examining the modal reduction accuracy of several blade analysis formulations. It is shown that classical, displacement-based finite elements are ill-suited for rotor blade analysis because they can't accurately represent the axial strain in modal space, and that this problem may be solved by employing the axial force as a variable in the analysis. It is shown that the mixed finite element method is a convenient means for accomplishing this, and the derivation of a mixed finite element for rotor blade analysis is outlined. A shortcoming of the mixed finite element method is that is that it increases the number of variables in the analysis. It is demonstrated that this problem may be rectified by solving for the axial displacements in terms of the axial forces and the bending displacements. Effectively, this procedure constitutes a generalization of the widely used axial elongation method to blades of arbitrary topology. The procedure is developed first for a single element, and then extended to an arbitrary assemblage of elements of arbitrary type. Finally, it is shown that the generalized axial elongation method is essentially an approximate solution for an invariant manifold that can be used as the basis for a nonlinear normal mode.

Cyclic structural analyses of anisotropic turbine blades for reusable space propulsion systems. [ssme fuel turbopump

NASA Technical Reports Server (NTRS)

Manderscheid, J. M.; Kaufman, A.

1985-01-01

Turbine blades for reusable space propulsion systems are subject to severe thermomechanical loading cycles that result in large inelastic strains and very short lives. These components require the use of anisotropic high-temperature alloys to meet the safety and durability requirements of such systems. To assess the effects on blade life of material anisotropy, cyclic structural analyses are being performed for the first stage high-pressure fuel turbopump blade of the space shuttle main engine. The blade alloy is directionally solidified MAR-M 246 alloy. The analyses are based on a typical test stand engine cycle. Stress-strain histories at the airfoil critical location are computed using the MARC nonlinear finite-element computer code. The MARC solutions are compared to cyclic response predictions from a simplified structural analysis procedure developed at the NASA Lewis Research Center.

Turbojet engine blade damping

NASA Technical Reports Server (NTRS)

Srinivasan, A. V.; Cutts, D. G.; Sridhar, S.

1981-01-01

The potentials of various sources of nonaerodynamic damping in engine blading are evaluated through a combination of advanced analysis and testing. The sources studied include material hysteresis, dry friction at shroud and root disk interfaces as well as at platform type external dampers. A limited seris of tests was conducted to evaluate damping capacities of composite materials (B/AL, B/AL/Ti) and thermal barrier coatings. Further, basic experiments were performed on titanium specimens to establish the characteristics of sliding friction and to determine material damping constants J and n. All the tests were conducted on single blades. Mathematical models were develthe several mechanisms of damping. Procedures to apply this data to predict damping levels in an assembly of blades are developed and discussed.

Development of gas-pressure bonding process for air-cooled turbine blades

NASA Technical Reports Server (NTRS)

Meiners, K. E.

1972-01-01

An investigation was conducted on the application of gas-pressure bonding to the joining of components for convectively cooled turbine blades and vanes. A processing procedure was established for joining the fins of Udimet 700 and TD NiCr sheet metal airfoil shells to cast B1900 struts without the use of internal support tooling. Alternative methods employing support tooling were investigated. Testing procedures were developed and employed to determine shear strengths and internal burst pressures of flat and cylindrical bonded finned shell configurations at room temperature and 1750 F. Strength values were determined parallel and transverse to the cooling fin direction. The effect of thermal cycles from 1750 F to room temperature on strength was also investigated.

An interactive grid generation procedure for axial and radial flow turbomachinery

NASA Technical Reports Server (NTRS)

Beach, Timothy A.

1989-01-01

A combination algebraic/elliptic technique is presented for the generation of three dimensional grids about turbo-machinery blade rows for both axial and radial flow machinery. The technique is built around use of an advanced engineering workstation to construct several two dimensional grids interactively on predetermined blade-to-blade surfaces. A three dimensional grid is generated by interpolating these surface grids onto an axisymmetric grid. On each blade-to-blade surface, a grid is created using algebraic techniques near the blade to control orthogonality within the boundary layer region and elliptic techniques in the mid-passage to achieve smoothness. The interactive definition of bezier curves as internal boundaries is the key to simple construction. This procedure lends itself well to zonal grid construction, an important example being the tip clearance region. Calculations done to date include a space shuttle main engine turbopump blade, a radial inflow turbine blade, and the first stator of the United Technologies Research Center large scale rotating rig. A finite Navier-Stokes solver was used in each case.

Subsurface Stress Fields in FCC Single Crystal Anisotropic Contacts

NASA Technical Reports Server (NTRS)

Arakere, Nagaraj K.; Knudsen, Erik; Swanson, Gregory R.; Duke, Gregory; Ham-Battista, Gilda

2004-01-01

Single crystal superalloy turbine blades used in high pressure turbomachinery are subject to conditions of high temperature, triaxial steady and alternating stresses, fretting stresses in the blade attachment and damper contact locations, and exposure to high-pressure hydrogen. The blades are also subjected to extreme variations in temperature during start-up and shutdown transients. The most prevalent high cycle fatigue (HCF) failure modes observed in these blades during operation include crystallographic crack initiation/propagation on octahedral planes, and non-crystallographic initiation with crystallographic growth. Numerous cases of crack initiation and crack propagation at the blade leading edge tip, blade attachment regions, and damper contact locations have been documented. Understanding crack initiation/propagation under mixed-mode loading conditions is critical for establishing a systematic procedure for evaluating HCF life of single crystal turbine blades. This paper presents analytical and numerical techniques for evaluating two and three dimensional subsurface stress fields in anisotropic contacts. The subsurface stress results are required for evaluating contact fatigue life at damper contacts and dovetail attachment regions in single crystal nickel-base superalloy turbine blades. An analytical procedure is presented for evaluating the subsurface stresses in the elastic half-space, based on the adaptation of a stress function method outlined by Lekhnitskii. Numerical results are presented for cylindrical and spherical anisotropic contacts, using finite element analysis (FEA). Effects of crystal orientation on stress response and fatigue life are examined. Obtaining accurate subsurface stress results for anisotropic single crystal contact problems require extremely refined three-dimensional (3-D) finite element grids, especially in the edge of contact region. Obtaining resolved shear stresses (RSS) on the principal slip planes also involves considerable post-processing work. For these reasons it is very advantageous to develop analytical solution schemes for subsurface stresses, whenever possible.

Blade selection for a modern axial-flow compressor

NASA Technical Reports Server (NTRS)

Wright, L. C.

1974-01-01

The procedures leading to successful design of an axial flow compressor are discussed. The three related approaches to cascade selection are: (1) experimental approach which relies on the use of experimental results from identical cascades to satisfy the velocity diagrams calculated, (2) a purely analytical procedure whereby blade shapes are calculated from the theoretical cascade and viscous flow equations, and (3) a semiempirical procedure which used experimental data together with the theoretically derived functional relations to relate the cascade parameters. Diagrams of typical transonic blade sections with uncambered leading edges are presented.

A method to combine hydrodynamics and constructive design in the optimization of the runner blades of Kaplan turbines

NASA Astrophysics Data System (ADS)

Miclosina, C. O.; Balint, D. I.; Campian, C. V.; Frunzaverde, D.; Ion, I.

2012-11-01

This paper deals with the optimization of the axial hydraulic turbines of Kaplan type. The optimization of the runner blade is presented systematically from two points of view: hydrodynamic and constructive. Combining these aspects in order to gain a safer operation when unsteady effects occur in the runner of the turbine is attempted. The design and optimization of the runner blade is performed with QTurbo3D software developed at the Center for Research in Hydraulics, Automation and Thermal Processes (CCHAPT) from "Eftimie Murgu" University of Resita, Romania. QTurbo3D software offers possibilities to design the meridian channel of hydraulic turbines design the blades and optimize the runner blade. 3D modeling and motion analysis of the runner blade operating mechanism are accomplished using SolidWorks software. The purpose of motion study is to obtain forces, torques or stresses in the runner blade operating mechanism, necessary to estimate its lifetime. This paper clearly states the importance of combining the hydrodynamics with the structural design in the optimization procedure of the runner of hydraulic turbines.

Development of a multiple-parameter nonlinear perturbation procedure for transonic turbomachinery flows: Preliminary application to design/optimization problems

NASA Technical Reports Server (NTRS)

Stahara, S. S.; Elliott, J. P.; Spreiter, J. R.

1983-01-01

An investigation was conducted to continue the development of perturbation procedures and associated computational codes for rapidly determining approximations to nonlinear flow solutions, with the purpose of establishing a method for minimizing computational requirements associated with parametric design studies of transonic flows in turbomachines. The results reported here concern the extension of the previously developed successful method for single parameter perturbations to simultaneous multiple-parameter perturbations, and the preliminary application of the multiple-parameter procedure in combination with an optimization method to blade design/optimization problem. In order to provide as severe a test as possible of the method, attention is focused in particular on transonic flows which are highly supercritical. Flows past both isolated blades and compressor cascades, involving simultaneous changes in both flow and geometric parameters, are considered. Comparisons with the corresponding exact nonlinear solutions display remarkable accuracy and range of validity, in direct correspondence with previous results for single-parameter perturbations.

Advanced Vibration Analysis Tool Developed for Robust Engine Rotor Designs

NASA Technical Reports Server (NTRS)

Min, James B.

2005-01-01

The primary objective of this research program is to develop vibration analysis tools, design tools, and design strategies to significantly improve the safety and robustness of turbine engine rotors. Bladed disks in turbine engines always feature small, random blade-to-blade differences, or mistuning. Mistuning can lead to a dramatic increase in blade forced-response amplitudes and stresses. Ultimately, this results in high-cycle fatigue, which is a major safety and cost concern. In this research program, the necessary steps will be taken to transform a state-of-the-art vibration analysis tool, the Turbo- Reduce forced-response prediction code, into an effective design tool by enhancing and extending the underlying modeling and analysis methods. Furthermore, novel techniques will be developed to assess the safety of a given design. In particular, a procedure will be established for using natural-frequency curve veerings to identify ranges of operating conditions (rotational speeds and engine orders) in which there is a great risk that the rotor blades will suffer high stresses. This work also will aid statistical studies of the forced response by reducing the necessary number of simulations. Finally, new strategies for improving the design of rotors will be pursued.

Blade pitch optimization methods for vertical-axis wind turbines

NASA Astrophysics Data System (ADS)

Kozak, Peter

Vertical-axis wind turbines (VAWTs) offer an inherently simpler design than horizontal-axis machines, while their lower blade speed mitigates safety and noise concerns, potentially allowing for installation closer to populated and ecologically sensitive areas. While VAWTs do offer significant operational advantages, development has been hampered by the difficulty of modeling the aerodynamics involved, further complicated by their rotating geometry. This thesis presents results from a simulation of a baseline VAWT computed using Star-CCM+, a commercial finite-volume (FVM) code. VAWT aerodynamics are shown to be dominated at low tip-speed ratios by dynamic stall phenomena and at high tip-speed ratios by wake-blade interactions. Several optimization techniques have been developed for the adjustment of blade pitch based on finite-volume simulations and streamtube models. The effectiveness of the optimization procedure is evaluated and the basic architecture for a feedback control system is proposed. Implementation of variable blade pitch is shown to increase a baseline turbine's power output between 40%-100%, depending on the optimization technique, improving the turbine's competitiveness when compared with a commercially-available horizontal-axis turbine.

Effect of Crystal Orientation on Fatigue Failure of Single Crystal Nickel Base Turbine Blade Superalloys

NASA Technical Reports Server (NTRS)

Arakere, Nagaraj K.; Swanson, Gregory R.

2000-01-01

High Cycle Fatigue (HCF) induced failures in aircraft gas-turbine engines is a pervasive problem affecting a wide range of components and materials. HCF is currently the primary cause of component failures in gas turbine aircraft engines. Turbine blades in high performance aircraft and rocket engines are increasingly being made of single crystal nickel superalloys. Single-crystal Nickel-base superalloys were developed to provide superior creep, stress rupture, melt resistance and thermomechanical fatigue capabilities over polycrystalline alloys previously used in the production of turbine blades and vanes. Currently the most widely used single crystal turbine blade superalloys are PWA 1480/1493 and PWA 1484. These alloys play an important role in commercial, military and space propulsion systems. PWA1493, identical to PWA1480, but with tighter chemical constituent control, is used in the NASA SSME (Space Shuttle Main Engine) alternate turbopump, a liquid hydrogen fueled rocket engine. Objectives for this paper are motivated by the need for developing failure criteria and fatigue life evaluation procedures for high temperature single crystal components, using available fatigue data and finite element modeling of turbine blades. Using the FE (finite element) stress analysis results and the fatigue life relations developed, the effect of variation of primary and secondary crystal orientations on life is determined, at critical blade locations. The most advantageous crystal orientation for a given blade design is determined. Results presented demonstrates that control of secondary and primary crystallographic orientation has the potential to optimize blade design by increasing its resistance to fatigue crack growth without adding additional weight or cost.

Development of multidisciplinary design optimization procedures for smart composite wings and turbomachinery blades

NASA Astrophysics Data System (ADS)

Jha, Ratneshwar

Multidisciplinary design optimization (MDO) procedures have been developed for smart composite wings and turbomachinery blades. The analysis and optimization methods used are computationally efficient and sufficiently rigorous. Therefore, the developed MDO procedures are well suited for actual design applications. The optimization procedure for the conceptual design of composite aircraft wings with surface bonded piezoelectric actuators involves the coupling of structural mechanics, aeroelasticity, aerodynamics and controls. The load carrying member of the wing is represented as a single-celled composite box beam. Each wall of the box beam is analyzed as a composite laminate using a refined higher-order displacement field to account for the variations in transverse shear stresses through the thickness. Therefore, the model is applicable for the analysis of composite wings of arbitrary thickness. Detailed structural modeling issues associated with piezoelectric actuation of composite structures are considered. The governing equations of motion are solved using the finite element method to analyze practical wing geometries. Three-dimensional aerodynamic computations are performed using a panel code based on the constant-pressure lifting surface method to obtain steady and unsteady forces. The Laplace domain method of aeroelastic analysis produces root-loci of the system which gives an insight into the physical phenomena leading to flutter/divergence and can be efficiently integrated within an optimization procedure. The significance of the refined higher-order displacement field on the aeroelastic stability of composite wings has been established. The effect of composite ply orientations on flutter and divergence speeds has been studied. The Kreisselmeier-Steinhauser (K-S) function approach is used to efficiently integrate the objective functions and constraints into a single envelope function. The resulting unconstrained optimization problem is solved using the Broyden-Fletcher-Goldberg-Shanno algorithm. The optimization problem is formulated with the objective of simultaneously minimizing wing weight and maximizing its aerodynamic efficiency. Design variables include composite ply orientations, ply thicknesses, wing sweep, piezoelectric actuator thickness and actuator voltage. Constraints are placed on the flutter/divergence dynamic pressure, wing root stresses and the maximum electric field applied to the actuators. Numerical results are presented showing significant improvements, after optimization, compared to reference designs. The multidisciplinary optimization procedure for the design of turbomachinery blades integrates aerodynamic and heat transfer design objective criteria along with various mechanical and geometric constraints on the blade geometry. The airfoil shape is represented by Bezier-Bernstein polynomials, which results in a relatively small number of design variables for the optimization. Thin shear layer approximation of the Navier-Stokes equation is used for the viscous flow calculations. Grid generation is accomplished by solving Poisson equations. The maximum and average blade temperatures are obtained through a finite element analysis. Total pressure and exit kinetic energy losses are minimized, with constraints on blade temperatures and geometry. The constrained multiobjective optimization problem is solved using the K-S function approach. The results for the numerical example show significant improvements after optimization.

Compressible, unsteady lifting-surface theory for a helicopter rotor in forward flight

NASA Technical Reports Server (NTRS)

Runyan, H. L.; Tai, H.

1985-01-01

A lifting-surface theory has been developed for a helicopter rotor in forward flight for compressible and incompressible flow. The method utilizes the concept of the linearized acceleration potential and makes use of the doublet lattice procedure. Calculations demonstrating the application of the method are given in terms of the lift distribution on a one-bladed rotor, a two-bladed rotor, and a rotor with swept-forward and swept-back tips. Also, the lift on a rotor vibrating in a pitching mode at 4 per revolution is given. Compressibility effects and interference effects for a two-bladed rotor are discussed.

Optimum Design of High Speed Prop-Rotors

NASA Technical Reports Server (NTRS)

Chattopadhyay, Aditi

1992-01-01

The objective of this research is to develop optimization procedures to provide design trends in high speed prop-rotors. The necessary disciplinary couplings are all considered within a closed loop optimization process. The procedures involve the consideration of blade aeroelastic, aerodynamic performance, structural and dynamic design requirements. Further, since the design involves consideration of several different objectives, multiobjective function formulation techniques are developed.

Prediction of dynamic and aerodynamic characteristics of the centrifugal fan with forward curved blades

NASA Astrophysics Data System (ADS)

Polanský, Jiří; Kalmár, László; Gášpár, Roman

2013-12-01

The main aim of this paper is determine the centrifugal fan with forward curved blades aerodynamic characteristics based on numerical modeling. Three variants of geometry were investigated. The first, basic "A" variant contains 12 blades. The geometry of second "B" variant contains 12 blades and 12 semi-blades with optimal length [1]. The third, control variant "C" contains 24 blades without semi-blades. Numerical calculations were performed by CFD Ansys. Another aim of this paper is to compare results of the numerical simulation with results of approximate numerical procedure. Applied approximate numerical procedure [2] is designated to determine characteristics of the turbulent flow in the bladed space of a centrifugal-flow fan impeller. This numerical method is an extension of the hydro-dynamical cascade theory for incompressible and inviscid fluid flow. Paper also partially compares results from the numerical simulation and results from the experimental investigation. Acoustic phenomena observed during experiment, during numerical simulation manifested as deterioration of the calculation stability, residuals oscillation and thus also as a flow field oscillation. Pressure pulsations are evaluated by using frequency analysis for each variant and working condition.

On the development of a magnetoresistive sensor for blade tip timing and blade tip clearance measurement systems.

PubMed

Tomassini, R; Rossi, G; Brouckaert, J-F

2016-10-01

A simultaneous blade tip timing (BTT) and blade tip clearance (BTC) measurement system enables the determination of turbomachinery blade vibrations and ensures the monitoring of the existing running gaps between the blade tip and the casing. This contactless instrumentation presents several advantages compared to the well-known telemetry system with strain gauges, at the cost of a more complex data processing procedure. The probes used can be optical, capacitive, eddy current as well as microwaves, everyone with its dedicated electronics and many existing different signal processing algorithms. Every company working in this field has developed its own processing method and sensor technology. Hence, repeating the same test with different instrumentations, the answer is often different. Moreover, rarely it is possible to achieve reliability for in-service measurements. Developments are focused on innovative instrumentations and a common standard. This paper focuses on the results achieved using a novel magnetoresistive sensor for simultaneous tip timing and tip clearance measurements. The sensor measurement principle is described. The sensitivity to gap variation is investigated. In terms of measurement of vibrations, experimental investigations were performed at the Air Force Institute of Technology (ITWL, Warsaw, Poland) in a real aeroengine and in the von Karman Institute (VKI) R2 compressor rig. The advantages and limitations of the magnetoresistive probe for turbomachinery testing are highlighted.

On the development of a magnetoresistive sensor for blade tip timing and blade tip clearance measurement systems

NASA Astrophysics Data System (ADS)

Tomassini, R.; Rossi, G.; Brouckaert, J.-F.

2016-10-01

A simultaneous blade tip timing (BTT) and blade tip clearance (BTC) measurement system enables the determination of turbomachinery blade vibrations and ensures the monitoring of the existing running gaps between the blade tip and the casing. This contactless instrumentation presents several advantages compared to the well-known telemetry system with strain gauges, at the cost of a more complex data processing procedure. The probes used can be optical, capacitive, eddy current as well as microwaves, everyone with its dedicated electronics and many existing different signal processing algorithms. Every company working in this field has developed its own processing method and sensor technology. Hence, repeating the same test with different instrumentations, the answer is often different. Moreover, rarely it is possible to achieve reliability for in-service measurements. Developments are focused on innovative instrumentations and a common standard. This paper focuses on the results achieved using a novel magnetoresistive sensor for simultaneous tip timing and tip clearance measurements. The sensor measurement principle is described. The sensitivity to gap variation is investigated. In terms of measurement of vibrations, experimental investigations were performed at the Air Force Institute of Technology (ITWL, Warsaw, Poland) in a real aeroengine and in the von Karman Institute (VKI) R2 compressor rig. The advantages and limitations of the magnetoresistive probe for turbomachinery testing are highlighted.

Structural optimization procedure of a composite wind turbine blade for reducing both material cost and blade weight

NASA Astrophysics Data System (ADS)

Hu, Weifei; Park, Dohyun; Choi, DongHoon

2013-12-01

A composite blade structure for a 2 MW horizontal axis wind turbine is optimally designed. Design requirements are simultaneously minimizing material cost and blade weight while satisfying the constraints on stress ratio, tip deflection, fatigue life and laminate layup requirements. The stress ratio and tip deflection under extreme gust loads and the fatigue life under a stochastic normal wind load are evaluated. A blade element wind load model is proposed to explain the wind pressure difference due to blade height change during rotor rotation. For fatigue life evaluation, the stress result of an implicit nonlinear dynamic analysis under a time-varying fluctuating wind is converted to the histograms of mean and amplitude of maximum stress ratio using the rainflow counting algorithm Miner's rule is employed to predict the fatigue life. After integrating and automating the whole analysis procedure an evolutionary algorithm is used to solve the discrete optimization problem.

Energy efficient engine, high pressure turbine thermal barrier coating. Support technology report

NASA Technical Reports Server (NTRS)

Duderstadt, E. C.; Agarwal, P.

1983-01-01

This report describes the work performed on a thermal barrier coating support technology task of the Energy Efficient Engine Component Development Program. A thermal barrier coating (TBC) system consisting of a Ni-Cr-Al-Y bond cost layer and ZrO2-Y2O3 ceramic layer was selected from eight candidate coating systems on the basis of laboratory tests. The selection was based on coating microstructure, crystallographic phase composition, tensile bond and bend test results, erosion and impact test results, furnace exposure, thermal cycle, and high velocity dynamic oxidation test results. Procedures were developed for applying the selected TBC to CF6-50, high pressure turbine blades and vanes. Coated HPT components were tested in three kinds of tests. Stage 1 blades were tested in a cascade cyclic test rig, Stage 2 blades were component high cycle fatigue tested to qualify thermal barrier coated blades for engine testing, and Stage 2 blades and Stage 1 and 2 vanes were run in factory engine tests. After completion of the 1000 cycle engine test, the TBC on the blades was in excellent condition over all of the platform and airfoil except at the leading edge above midspan on the suction side of the airfoil. The coating damage appeared to be caused by particle impingement; adjacent blades without TBC also showed evidence of particle impingement.

An efficient constraint to account for mistuning effects in the optimal design of engine rotors

NASA Technical Reports Server (NTRS)

Murthy, Durbha V.; Pierre, Christophe; Ottarsson, Gisli

1992-01-01

Blade-to-blade differences in structural properties, unavoidable in practice due to manufacturing tolerances, can have significant influence on the vibratory response of engine rotor blade. Accounting for these differences, also known as mistuning, in design and in optimization procedures is generally not possible. This note presents an easily calculated constraint that can be used in design and optimization procedures to control the sensitivity of final designs to mistuning.

Aero/structural tailoring of engine blades (AERO/STAEBL)

NASA Technical Reports Server (NTRS)

Brown, K. W.

1988-01-01

This report describes the Aero/Structural Tailoring of Engine Blades (AERO/STAEBL) program, which is a computer code used to perform engine fan and compressor blade aero/structural numerical optimizations. These optimizations seek a blade design of minimum operating cost that satisfies realistic blade design constraints. This report documents the overall program (i.e., input, optimization procedures, approximate analyses) and also provides a detailed description of the validation test cases.

A viscous-inviscid interactive compressor calculations

NASA Technical Reports Server (NTRS)

Johnston, W.; Sockol, P. M.

1978-01-01

A viscous-inviscid interactive procedure for subsonic flow is developed and applied to an axial compressor stage. Calculations are carried out on a two-dimensional blade-to-blade region of constant radius assumed to occupy a mid-span location. Hub and tip effects are neglected. The Euler equations are solved by MacCormack's method, a viscous marching procedure is used in the boundary layers and wake, and an iterative interaction scheme is constructed that matches them in a way that incorporates information related to momentum and enthalpy thicknesses as well as the displacement thickness. The calculations are quasi-three-dimensional in the sense that the boundary layer and wake solutions allow for the presence of spanwise (radial) velocities.

Thin film thermocouples for high temperature turbine application

NASA Technical Reports Server (NTRS)

Martin, Lisa C.

1991-01-01

The objective is to develop thin film thermocouples (TFTC) for Space Shuttle Main Engine (SSME) components such as the high pressure fuel turbopump (HPFTP) blades and to test TFTC survivability and durability in the SSME environment. The purpose for developing TFTC's for SSME components is to obtain blade temperatures for computational models developed for fluid mechanics and structures. The TFTC must be able to withstand the presence of high temperature, high pressure hydrogen as well as a severe thermal transient due to a cryogenic to combustion temperature change. The TFTC's will eventually be installed and tested on SSME propulsion system components in the SSME test bed engine. The TFTC's were successfully fabricated on flat coupons of MAR-M 246 (Hf+), which is the superalloy material used for HPFTP turbine blades. The TFTC's fabricated on flat coupons survived thermal shock cycling as well as testing in a heat flux measurement facility which provided a rapid thermal transient. The same fabrication procedure was used to deposit TFTC's on HPFTP first stage rotor blades. Other results from the experiments are presented, and future testing plans are discussed.

14 CFR Appendix J to Part 36 - Alternative Noise Certification Procedure for Helicopters Under Subpart H Having a Maximum...

Code of Federal Regulations, 2010 CFR

2010-01-01

... produce the same advancing blade tip Mach number as associated with the reference conditions; (i) Advancing blade tip Mach number (MAT) is defined as the ratio of the arithmetic sum of blade tip rotational... the reference advancing blade tip Mach number. The adjusted reference airspeed shall be maintained...

14 CFR Appendix J to Part 36 - Alternative Noise Certification Procedure for Helicopters Under Subpart H Having a Maximum...

Code of Federal Regulations, 2011 CFR

2011-01-01

... produce the same advancing blade tip Mach number as associated with the reference conditions; (i) Advancing blade tip Mach number (MAT) is defined as the ratio of the arithmetic sum of blade tip rotational... the reference advancing blade tip Mach number. The adjusted reference airspeed shall be maintained...

14 CFR Appendix J to Part 36 - Alternative Noise Certification Procedure for Helicopters Under Subpart H Having a Maximum...

Code of Federal Regulations, 2012 CFR

2012-01-01

... produce the same advancing blade tip Mach number as associated with the reference conditions; (i) Advancing blade tip Mach number (MAT) is defined as the ratio of the arithmetic sum of blade tip rotational... the reference advancing blade tip Mach number. The adjusted reference airspeed shall be maintained...

14 CFR Appendix J to Part 36 - Alternative Noise Certification Procedure for Helicopters Under Subpart H Having a Maximum...

Code of Federal Regulations, 2013 CFR

2013-01-01

... produce the same advancing blade tip Mach number as associated with the reference conditions; (i) Advancing blade tip Mach number (MAT) is defined as the ratio of the arithmetic sum of blade tip rotational... the reference advancing blade tip Mach number. The adjusted reference airspeed shall be maintained...

14 CFR Appendix J to Part 36 - Alternative Noise Certification Procedure for Helicopters Under Subpart H Having a Maximum...

Code of Federal Regulations, 2014 CFR

2014-01-01

... produce the same advancing blade tip Mach number as associated with the reference conditions; (i) Advancing blade tip Mach number (MAT) is defined as the ratio of the arithmetic sum of blade tip rotational... the reference advancing blade tip Mach number. The adjusted reference airspeed shall be maintained...

Structural design of composite rotor blades with consideration of manufacturability, durability, and manufacturing uncertainties

NASA Astrophysics Data System (ADS)

Li, Leihong

A modular structural design methodology for composite blades is developed. This design method can be used to design composite rotor blades with sophisticate geometric cross-sections. This design method hierarchically decomposed the highly-coupled interdisciplinary rotor analysis into global and local levels. In the global level, aeroelastic response analysis and rotor trim are conduced based on multi-body dynamic models. In the local level, variational asymptotic beam sectional analysis methods are used for the equivalent one-dimensional beam properties. Compared with traditional design methodology, the proposed method is more efficient and accurate. Then, the proposed method is used to study three different design problems that have not been investigated before. The first is to add manufacturing constraints into design optimization. The introduction of manufacturing constraints complicates the optimization process. However, the design with manufacturing constraints benefits the manufacturing process and reduces the risk of violating major performance constraints. Next, a new design procedure for structural design against fatigue failure is proposed. This procedure combines the fatigue analysis with the optimization process. The durability or fatigue analysis employs a strength-based model. The design is subject to stiffness, frequency, and durability constraints. Finally, the manufacturing uncertainty impacts on rotor blade aeroelastic behavior are investigated, and a probabilistic design method is proposed to control the impacts of uncertainty on blade structural performance. The uncertainty factors include dimensions, shapes, material properties, and service loads.

Recent Advances in Heliogyro Solar Sail Structural Dynamics, Stability, and Control Research

NASA Technical Reports Server (NTRS)

Wilkie, W. Keats; Warren, Jerry E.; Horta, Lucas G.; Lyle, Karen H.; Juang, Jer-Nan; Gibbs, S. Chad; Dowell, Earl H.; Guerrant, Daniel V.; Lawrence, Dale

2015-01-01

Results from recent NASA sponsored research on the structural dynamics, stability, and control characteristics of heliogyro solar sails are summarized. Specific areas under investigation include coupled nonlinear finite element analysis of heliogyro membrane blade with solar radiation pressure effects, system identification of spinning membrane structures, and solarelastic stability analysis of heliogyro solar sails, including stability during blade deployment. Recent results from terrestrial 1-g blade dynamics and control experiments on "rope ladder" membrane blade analogs, and small-scale in vacuo system identification experiments with hanging and spinning high-aspect ratio membranes will also be presented. A low-cost, rideshare payload heliogyro technology demonstration mission concept is used as a mission context for these heliogyro structural dynamics and solarelasticity investigations, and is also described. Blade torsional dynamic response and control are also shown to be significantly improved through the use of edge stiffening structural features or inclusion of modest tip masses to increase centrifugal stiffening of the blade structure. An output-only system identification procedure suitable for on-orbit blade dynamics investigations is also developed and validated using ground tests of spinning sub-scale heliogyro blade models. Overall, analytical and experimental investigations to date indicate no intractable stability or control issues for the heliogyro solar sail concept.

Investigation of Advanced Counterrotation Blade Configuration Concepts for High Speed Turboprop Systems. Task 3: Advanced Fan Section Grid Generator Final Report and Computer Program User's Manual

NASA Technical Reports Server (NTRS)

Crook, Andrew J.; Delaney, Robert A.

1991-01-01

A procedure is studied for generating three-dimensional grids for advanced turbofan engine fan section geometries. The procedure constructs a discrete mesh about engine sections containing the fan stage, an arbitrary number of axisymmetric radial flow splitters, a booster stage, and a bifurcated core/bypass flow duct with guide vanes. The mesh is an h-type grid system, the points being distributed with a transfinite interpolation scheme with axial and radial spacing being user specified. Elliptic smoothing of the grid in the meridional plane is a post-process option. The grid generation scheme is consistent with aerodynamic analyses utilizing the average-passage equation system developed by Dr. John Adamczyk of NASA Lewis. This flow solution scheme requires a series of blade specific grids each having a common axisymmetric mesh, but varying in the circumferential direction according to the geometry of the specific blade row.

Fabrication of composite propfan blades for a cruise missile wind tunnel model

NASA Technical Reports Server (NTRS)

Fite, E. Brian

1993-01-01

This report outlines the procedures that were employed in fabricating prototype graphite-epoxy composite prop fan blades. These blades were used in wind tunnel tests that investigated prop fan propulsion system interactions with a missile airframe in order to study the feasibility of an advanced-technology-propfan-propelled missile. Major phases of the blade fabrication presented include machining of the master blade, mold fabrication, ply cutting and assembly, blade curing, and quality assurance. Specifically, four separate designs were fabricated, 18 blades of each geometry, using the same fabrication technique for each design.

Composite casting/bonding construction of an air-cooled, high temperature radial turbine wheel

NASA Technical Reports Server (NTRS)

Hammer, A. N.; Aigret, G.; Rodgers, C.; Metcalfe, A. G.

1983-01-01

A composite casting/bonding technique has been developed for the fabrication of a unique air-cooled, high temperature radial inflow turbine wheel design applicable to auxilliary power units with small rotor diameters and blade entry heights. The 'split blade' manufacturing procedure employed is an alternative to complex internal ceramic coring. Attention is given to both aerothermodynamic and structural design, of which the latter made advantageous use of the exploration of alternative cooling passage configurations through CAD/CAM system software modification.

Reconstruction method for running shape of rotor blade considering nonlinear stiffness and loads

NASA Astrophysics Data System (ADS)

Wang, Yongliang; Kang, Da; Zhong, Jingjun

2017-10-01

The aerodynamic and centrifugal loads acting on the rotating blade make the blade configuration deformed comparing to its shape at rest. Accurate prediction of the running blade configuration plays a significant role in examining and analyzing turbomachinery performance. Considering nonlinear stiffness and loads, a reconstruction method is presented to address transformation of a rotating blade from cold to hot state. When calculating blade deformations, the blade stiffness and load conditions are updated simultaneously as blade shape varies. The reconstruction procedure is iterated till a converged hot blade shape is obtained. This method has been employed to determine the operating blade shapes of a test rotor blade and the Stage 37 rotor blade. The calculated results are compared with the experiments. The results show that the proposed method used for blade operating shape prediction is effective. The studies also show that this method can improve precision of finite element analysis and aerodynamic performance analysis.

Integrated aerodynamic/dynamic/structural optimization of helicopter rotor blades using multilevel decomposition

NASA Technical Reports Server (NTRS)

Walsh, Joanne L.; Young, Katherine C.; Pritchard, Jocelyn I.; Adelman, Howard M.; Mantay, Wayne R.

1995-01-01

This paper describes an integrated aerodynamic/dynamic/structural (IADS) optimization procedure for helicopter rotor blades. The procedure combines performance, dynamics, and structural analyses with a general-purpose optimizer using multilevel decomposition techniques. At the upper level, the structure is defined in terms of global quantities (stiffness, mass, and average strains). At the lower level, the structure is defined in terms of local quantities (detailed dimensions of the blade structure and stresses). The IADS procedure provides an optimization technique that is compatible with industrial design practices in which the aerodynamic and dynamic designs are performed at a global level and the structural design is carried out at a detailed level with considerable dialog and compromise among the aerodynamic, dynamic, and structural groups. The IADS procedure is demonstrated for several examples.

Multilevel decomposition approach to integrated aerodynamic/dynamic/structural optimization of helicopter rotor blades

NASA Technical Reports Server (NTRS)

Walsh, Joanne L.; Young, Katherine C.; Pritchard, Jocelyn I.; Adelman, Howard M.; Mantay, Wayne R.

1994-01-01

This paper describes an integrated aerodynamic, dynamic, and structural (IADS) optimization procedure for helicopter rotor blades. The procedure combines performance, dynamics, and structural analyses with a general purpose optimizer using multilevel decomposition techniques. At the upper level, the structure is defined in terms of local quantities (stiffnesses, mass, and average strains). At the lower level, the structure is defined in terms of local quantities (detailed dimensions of the blade structure and stresses). The IADS procedure provides an optimization technique that is compatible with industrial design practices in which the aerodynamic and dynamic design is performed at a global level and the structural design is carried out at a detailed level with considerable dialogue and compromise among the aerodynamic, dynamic, and structural groups. The IADS procedure is demonstrated for several cases.

Computational design of a self-assembling symmetrical β-propeller protein.

PubMed

Voet, Arnout R D; Noguchi, Hiroki; Addy, Christine; Simoncini, David; Terada, Daiki; Unzai, Satoru; Park, Sam-Yong; Zhang, Kam Y J; Tame, Jeremy R H

2014-10-21

The modular structure of many protein families, such as β-propeller proteins, strongly implies that duplication played an important role in their evolution, leading to highly symmetrical intermediate forms. Previous attempts to create perfectly symmetrical propeller proteins have failed, however. We have therefore developed a new and rapid computational approach to design such proteins. As a test case, we have created a sixfold symmetrical β-propeller protein and experimentally validated the structure using X-ray crystallography. Each blade consists of 42 residues. Proteins carrying 2-10 identical blades were also expressed and purified. Two or three tandem blades assemble to recreate the highly stable sixfold symmetrical architecture, consistent with the duplication and fusion theory. The other proteins produce different monodisperse complexes, up to 42 blades (180 kDa) in size, which self-assemble according to simple symmetry rules. Our procedure is suitable for creating nano-building blocks from different protein templates of desired symmetry.

Material characterization of active fiber composites for integral twist-actuated rotor blade application

NASA Astrophysics Data System (ADS)

Wickramasinghe, Viresh K.; Hagood, Nesbitt W.

2004-10-01

The primary objective of this work was to perform material characterization of the active fiber composite (AFC) actuator system for the Boeing active material rotor (AMR) blade application. The purpose of the AMR was to demonstrate active vibration control in helicopters through integral twist-actuation of the blade. The AFCs were a new structural actuator system consisting of piezoceramic fibers embedded in an epoxy matrix and sandwiched between interdigitated electrodes to enhance actuation performance. These conformable actuators were integrated directly into the blade spar laminate as active plies within the composite structure to perform structural control. Therefore, extensive electromechanical material characterization was required to evaluate AFCs both as actuators and as structural components of the blade. The characterization tests designed to extract important electromechanical properties under simulated blade operating conditions included nominal actuation tests, stress-strain tests and actuation under tensile load tests. This paper presents the test results as well as the comprehensive testing procedure developed to evaluate the relevant properties of the AFCs for structural application. The material characterization tests provided an invaluable insight into the behavior of the AFCs under various electromechanical conditions. The results from this comprehensive material characterization of the AFC actuator system supported the design and operation of the AMR blades scheduled for wind tunnel tests.

A New Higher-Order Composite Theory for Analysis and Design of High Speed Tilt-Rotor Blades

NASA Technical Reports Server (NTRS)

McCarthy, Thomas Robert

1996-01-01

A higher-order theory is developed to model composite box beams with arbitrary wall thicknesses. The theory, based on a refined displacement field, represents a three-dimensional model which approximates the elasticity solution. Therefore, the cross-sectional properties are not reduced to one-dimensional beam parameters. Both inplane and out-of-plane warping are automatically included in the formulation. The model accurately captures the transverse shear stresses through the thickness of each wall while satisfying all stress-free boundary conditions. Several numerical results are presented to validate the present theory. The developed theory is then used to model the load carrying member of a tilt-rotor blade which has thick-walled sections. The composite structural analysis is coupled with an aerodynamic analysis to compute the aeroelastic stability of the blade. Finally, a multidisciplinary optimization procedure is developed to improve the aerodynamic, structural and aeroelastic performance of the tilt-rotor aircraft. The Kreisselmeier-Steinhauser function is used to formulate the multiobjective function problem and a hybrid approximate analysis is used to reduce the computational effort. The optimum results are compared with the baseline values and show significant improvements in the overall performance of the tilt-rotor blade.

An integrated optimum design approach for high speed prop-rotors including acoustic constraints

NASA Technical Reports Server (NTRS)

Chattopadhyay, Aditi; Wells, Valana; Mccarthy, Thomas; Han, Arris

1993-01-01

The objective of this research is to develop optimization procedures to provide design trends in high speed prop-rotors. The necessary disciplinary couplings are all considered within a closed loop multilevel decomposition optimization process. The procedures involve the consideration of blade-aeroelastic aerodynamic performance, structural-dynamic design requirements, and acoustics. Further, since the design involves consideration of several different objective functions, multiobjective function formulation techniques are developed.

SSME single crystal turbine blade dynamics

NASA Technical Reports Server (NTRS)

Moss, Larry A.; Smith, Todd E.

1987-01-01

A study was performed to determine the dynamic characteristics of the Space Shuttle main engine high pressure fuel turbopump (HPFTP) blades made of single crystal (SC) material. The first and second stage drive turbine blades of HPFTP were examined. The nonrotating natural frequencies were determined experimentally and analytically. The experimental results of the SC second stage blade were used to verify the analytical procedures. The analytical study examined the SC first stage blade natural frequencies with respect to crystal orientation at typical operating conditions. The SC blade dynamic response was predicted to be less than the directionally solidified blade. Crystal axis orientation optimization indicated the third mode interference will exist in any SC orientation.

78 FR 40063 - Airworthiness Directives; Erickson Air-Crane Incorporated Helicopters (Type Certificate...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-03

... Sikorsky Model S-64E helicopters. The AD requires repetitive checks of the Blade Inspection Method (BIM... and check procedures for BIM blades installed on the Model S-64F helicopters. Several blade spars with a crack emanating from corrosion pits and other damage have been found because of BIM pressure...

Optimal placement of tuning masses for vibration reduction in helicopter rotor blades

NASA Technical Reports Server (NTRS)

Pritchard, Jocelyn I.; Adelman, Howard M.

1988-01-01

Described are methods for reducing vibration in helicopter rotor blades by determining optimum sizes and locations of tuning masses through formal mathematical optimization techniques. An optimization procedure is developed which employs the tuning masses and corresponding locations as design variables which are systematically changed to achieve low values of shear without a large mass penalty. The finite-element structural analysis of the blade and the optimization formulation require development of discretized expressions for two performance parameters: modal shaping parameter and modal shear amplitude. Matrix expressions for both quantities and their sensitivity derivatives are developed. Three optimization strategies are developed and tested. The first is based on minimizing the modal shaping parameter which indirectly reduces the modal shear amplitudes corresponding to each harmonic of airload. The second strategy reduces these amplitudes directly, and the third strategy reduces the shear as a function of time during a revolution of the blade. The first strategy works well for reducing the shear for one mode responding to a single harmonic of the airload, but has been found in some cases to be ineffective for more than one mode. The second and third strategies give similar results and show excellent reduction of the shear with a low mass penalty.

Thermal/Structural Tailoring of Engine Blades (T/STAEBL) User's manual

NASA Technical Reports Server (NTRS)

Brown, K. W.

1994-01-01

The Thermal/Structural Tailoring of Engine Blades (T/STAEBL) system is a computer code that is able to perform numerical optimizations of cooled jet engine turbine blades and vanes. These optimizations seek an airfoil design of minimum operating cost that satisfies realistic design constraints. This report documents the organization of the T/STAEBL computer program, its design and analysis procedure, its optimization procedure, and provides an overview of the input required to run the program, as well as the computer resources required for its effective use. Additionally, usage of the program is demonstrated through a validation test case.

Thermal/Structural Tailoring of Engine Blades (T/STAEBL): User's manual

NASA Astrophysics Data System (ADS)

Brown, K. W.

1994-03-01

The Thermal/Structural Tailoring of Engine Blades (T/STAEBL) system is a computer code that is able to perform numerical optimizations of cooled jet engine turbine blades and vanes. These optimizations seek an airfoil design of minimum operating cost that satisfies realistic design constraints. This report documents the organization of the T/STAEBL computer program, its design and analysis procedure, its optimization procedure, and provides an overview of the input required to run the program, as well as the computer resources required for its effective use. Additionally, usage of the program is demonstrated through a validation test case.

Dermatology Procedures

MedlinePlus

... excision") slices a surface growth off using a blade. A "curette" does a similar task with a ... pimples by using a needle or small pointed blade and expressing the lesions with an extractor. Back ...

Wavelet-based identification of rotor blades in passage-through-resonance tests

NASA Astrophysics Data System (ADS)

Carassale, Luigi; Marrè-Brunenghi, Michela; Patrone, Stefano

2018-01-01

Turbine blades are critical components in turbo engines and their design process usually includes experimental tests in order to validate and/or update numerical models. These tests are generally carried out on full-scale rotors having some blades instrumented with strain gauges and usually involve a run-up or a run-down phase. The quantification of damping in these conditions is rather challenging for several reasons. In this work, we show through numerical simulations that the usual identification procedures lead to a systematic overestimation of damping due both to the finite sweep velocity, as well as to the variation of the blade natural frequencies with the rotation speed. To overcome these problems, an identification procedure based on the continuous wavelet transform is proposed and validated through numerical simulation.

Design and fabrication of forward-swept counterrotation blade configuration for wind tunnel testing

NASA Technical Reports Server (NTRS)

Nichols, G. H.

1994-01-01

Work performed by GE Aircraft on advanced counterrotation blade configuration concepts for high speed turboprop system is described. Primary emphasis was placed on theoretically and experimentally evaluating the aerodynamic, aeromechanical, and acoustic performance of GE-defined counterrotating blade concepts. Several blade design concepts were considered. Feasibility studies were conducted to evaluate a forward-swept versus an aft-swept blade application and how the given blade design would affect interaction between rotors. Two blade designs were initially selected. Both designs involved in-depth aerodynamic, aeromechanical, mechanical, and acoustic analyses followed by the fabrication of forward-swept, forward rotor blade sets to be wind tunnel tested with an aft-swept, aft rotor blade set. A third blade set was later produced from a NASA design that was based on wind tunnel test results from the first two blade sets. This blade set had a stiffer outer ply material added to the original blade design, in order to reach the design point operating line. Detailed analyses, feasibility studies, and fabrication procedures for all blade sets are presented.

An integrated optimum design approach for high speed prop rotors

NASA Technical Reports Server (NTRS)

Chattopadhyay, Aditi; Mccarthy, Thomas R.

1995-01-01

The objective is to develop an optimization procedure for high-speed and civil tilt-rotors by coupling all of the necessary disciplines within a closed-loop optimization procedure. Both simplified and comprehensive analysis codes are used for the aerodynamic analyses. The structural properties are calculated using in-house developed algorithms for both isotropic and composite box beam sections. There are four major objectives of this study. (1) Aerodynamic optimization: The effects of blade aerodynamic characteristics on cruise and hover performance of prop-rotor aircraft are investigated using the classical blade element momentum approach with corrections for the high lift capability of rotors/propellers. (2) Coupled aerodynamic/structures optimization: A multilevel hybrid optimization technique is developed for the design of prop-rotor aircraft. The design problem is decomposed into a level for improved aerodynamics with continuous design variables and a level with discrete variables to investigate composite tailoring. The aerodynamic analysis is based on that developed in objective 1 and the structural analysis is performed using an in-house code which models a composite box beam. The results are compared to both a reference rotor and the optimum rotor found in the purely aerodynamic formulation. (3) Multipoint optimization: The multilevel optimization procedure of objective 2 is extended to a multipoint design problem. Hover, cruise, and take-off are the three flight conditions simultaneously maximized. (4) Coupled rotor/wing optimization: Using the comprehensive rotary wing code CAMRAD, an optimization procedure is developed for the coupled rotor/wing performance in high speed tilt-rotor aircraft. The developed procedure contains design variables which define the rotor and wing planforms.

Overview of Vertical Axis Wind Turbine (VAWT)

NASA Technical Reports Server (NTRS)

Sullivan, W. N.

1979-01-01

A survey is presented of the practices which were applied for designing VAWT blades. An attempt is made to discuss strengths and weaknesses of the existing procedures. Discussion is provided on planned or suggested future work in developing improved design tools.

Optimal mistuning for enhanced aeroelastic stability of transonic fans

NASA Technical Reports Server (NTRS)

Hall, K. C.; Crawley, E. F.

1983-01-01

An inverse design procedure was developed for the design of a mistuned rotor. The design requirements are that the stability margin of the eigenvalues of the aeroelastic system be greater than or equal to some minimum stability margin, and that the mass added to each blade be positive. The objective was to achieve these requirements with a minimal amount of mistuning. Hence, the problem was posed as a constrained optimization problem. The constrained minimization problem was solved by the technique of mathematical programming via augmented Lagrangians. The unconstrained minimization phase of this technique was solved by the variable metric method. The bladed disk was modelled as being composed of a rigid disk mounted on a rigid shaft. Each of the blades were modelled with a single tosional degree of freedom.

Integration of dynamic, aerodynamic, and structural optimization of helicopter rotor blades

NASA Technical Reports Server (NTRS)

Peters, David A.

1991-01-01

Summarized here is the first six years of research into the integration of structural, dynamic, and aerodynamic considerations in the design-optimization process for rotor blades. Specifically discussed here is the application of design optimization techniques for helicopter rotor blades. The reduction of vibratory shears and moments at the blade root, aeroelastic stability of the rotor, optimum airframe design, and an efficient procedure for calculating system sensitivities with respect to the design variables used are discussed.

MPT Prediction of Aircraft-Engine Fan Noise

NASA Technical Reports Server (NTRS)

Connell, Stuart D.

2004-01-01

A collection of computer programs has been developed that implements a procedure for predicting multiple-pure-tone (MPT) noise generated by fan blades of an aircraft engine (e.g., a turbofan engine). MPT noise arises when the fan is operating with supersonic relative tip Mach No. Under this flow condition, there is a strong upstream running shock. The strength and position of this shock are very sensitive to blade geometry variations. For a fan where all the blades are identical, the primary tone observed upstream of the fan will be the blade passing frequency. If there are small variations in geometry between blades, then tones below the blade passing frequency arise MPTs. Stagger angle differences as small as 0.1 can give rise to significant MPT. It is also noted that MPT noise is more pronounced when the fan is operating in an unstarted mode. Computational results using a three-dimensional flow solver to compute the complete annulus flow with non-uniform fans indicate that MPT noise can be estimated in a relatively simple way. Hence, once the effect of a typical geometry variation of one blade in an otherwise uniform blade row is known, the effect of all the blades being different can be quickly computed via superposition. Two computer programs that were developed as part of this work are used in conjunction with a user s computational fluid dynamics (CFD) code to predict MPT spectra for a fan with a specified set of geometric variations: (1) The first program ROTBLD reads the users CFD solution files for a single blade passage via an API (Application Program Interface). There are options to replicate and perturb the geometry with typical variations stagger, camber, thickness, and pitch. The multi-passage CFD solution files are then written in the user s file format using the API. (2) The second program SUPERPOSE requires two input files: the first is the circumferential upstream pressure distribution extracted from the CFD solution on the multi-passage mesh, the second file defines the geometry variations of each blade in a complete fan. Superposition is used to predict the spectra resulting from the geometric variations.

78 FR 20503 - Airworthiness Directives; Pratt & Whitney Canada Corp. Turboprop Engines

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-05

... Certification Office, FAA, may approve AMOCs to this AD. Use the procedures found in 14 CFR 39.19 to make your... proposed AD would require inspection of the 1st stage PT blades and the removal from service of those blades that fail the inspection or their replacement with blades eligible for installation. We are...

Research Turbine Leaves Legacy in Its Wake | News | NREL

Science.gov Websites

110. Two 340-foot cranes were needed to install the larger, 175-foot blades optimized for intermediate depending, to remove the blades, then the nacelle, and finally the tower, section by section. "Site operating the turbine, but also performing complex procedures-like changing out blades that weigh more than

Design and Test of Mixed-flow Impellers III : Design and Experimental Results for Impeller Model MFI-2A and Comparison with Impeller Model MFI-1A

NASA Technical Reports Server (NTRS)

Hamrick, Joseph T; Osborn, Walter M; Beede, William L

1953-01-01

A mixed-flow impeller was designed to give a prescribed blade-surface velocity distribution at mean blade height for a given hub-shroud profile. The blade shape at mean blade height, which was produced by the prescribed velocity distribution, was extended by means of radial lines to form the composite blade shape from hub to shroud. The resulting blade was relatively thick; therefore, it was necessary to retain the inverse blade taper which resulted from extension of the radial lines in order to prevent merging or near merging of the separate blades near the hub. For the first test version of the impeller, designated the MFI-2A, the blade height was arbitrarily made greater than that for the basic impeller (the MFI-2) to allow for viscous effects. At design equivalent speed of 1400 feet per second the peak pressure ratio and maximum adiabatic efficiency were 3.95 and 79 percent, respectively. The adiabatic efficiency of the MFI-2A is four points lower than that for impeller model MFI-1A, but because of the higher slip factor for the MFI-2A, the pressure ratios are approximately equal. The procedures followed in the design of the MFI-1A and MFI-2A were, in general, the same; and, although the prescribed initial condition resulted in geometrical configurations that were quite dissimilar, the resulting performance characteristics compare favorably with designs for which considerable development work has been necessary.

Slicing of silicon into sheet material. Silicon sheet growth development for the large area silicon sheet task of the low cost silicon solar array project. Third quarterly report, September 20, 1976--December 19, 1976

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holden, S.C.

1976-12-27

The stability of tensioned blades used in multiblade sawing does not seem to be the limitation in cutting with thin blades. So far, 0.010 cm thick blades have been totally unsuccessful. Recently, 0.015 cm blades have proven successful in wafering, offering an 0.005 cm reduction in the silicon used per slice. The failure of thin blades is characterized as a possible result of blade misalignment or from the inherent uncontrollability of the loose abrasive multiblade process. Corrective procedures will be employed in the assembly of packages to eliminate one type of blade misalignment. Two ingots were sliced with the samemore » batch of standard silicon carbide abrasive slurry to determine the useful lifetime of this expendable material. After 250 slices, the cutting efficiency had not degraded. Further tests will be continued to establish the maximum lifetime of both silicon carbide and boron carbide abrasive. Electron microscopy will be employed to evaluate the wear of abrasive particles in the failure of abrasive slurry. The surface damage of silicon wafers has been characterized as predominantly subsurface fracture. Damage with No. 600 SiC is between 10 and 15 microns into the wafer surface. This agrees well with previous investigations of damage from silicon carbide abrasive papers.« less

Graphite/epoxy composite stiffened panel fabrication development

NASA Technical Reports Server (NTRS)

Palmer, R. J.

1984-01-01

This report describes the manufacturing development procedures used to fabricate a series of carbon/epoxy panels with integrally molded stiffeners. Panel size was started at 6 inches by 18 inches and one stiffener and increased to 30 inches by 60 inches and six integral stiffeners. Stiffener concepts were optimized for minimum weight (or mass) to carry stress levels from 1500 lbs/inch to 25,000 lbs/inch compression load. Designs were created and manufactured with a stiffener configuration of integrally molded hat, J, I, sine wave I, solid blade, and honeycomb blade shapes. Successful and unsuccessful detail methods of tooling, lay-up methods, and bagging methods are documented. Recommendations are made for the best state-of-the-art manufacturing technique developed for type of stiffener construction.

Laser hardening techniques on steam turbine blade and application

NASA Astrophysics Data System (ADS)

Yao, Jianhua; Zhang, Qunli; Kong, Fanzhi; Ding, Qingming

Different laser surface hardening techniques, such as laser alloying and laser solution strengthening were adopted to perform modification treatment on the local region of inset edge for 2Cr13 and 17-4PH steam turbine blades to prolong the life of the blades. The microstructures, microhardness and anti-cavitation properties were investigated on the blades after laser treatment. The hardening mechanism and technique adaptability were researched. Large scale installation practices confirmed that the laser surface modification techniques are safe and reliable, which can improve the properties of blades greatly with advantages of high automation, high quality, little distortion and simple procedure.

SSME single-crystal turbine blade dynamics

NASA Technical Reports Server (NTRS)

Moss, Larry A.

1988-01-01

A study was performrd to determine the dynamic characteristics of the Space Shuttle Main Engine high pressure fuel turbopump (HPFTP) blades made of single crystal (SC) material. The first and second stage drive turbine blades of HPFTP were examined. The nonrotating natural frequencies were determined experimentally and analytically. The experimental results of the SC second stage blade were used to verify the analytical procedures. The study examined the SC first stage blade natural frequencies with respect to crystal orientation at typical operating conditions. The SC blade dynamic response was predicted to be less than the directionally solidified base. Crystal axis orientation optimization indicated that the third mode interference will exist in any SC orientation.

Large Scale Flutter Data for Design of Rotating Blades Using Navier-Stokes Equations

NASA Technical Reports Server (NTRS)

Guruswamy, Guru P.

2012-01-01

A procedure to compute flutter boundaries of rotating blades is presented; a) Navier-Stokes equations. b) Frequency domain method compatible with industry practice. Procedure is initially validated: a) Unsteady loads with flapping wing experiment. b) Flutter boundary with fixed wing experiment. Large scale flutter computation is demonstrated for rotating blade: a) Single job submission script. b) Flutter boundary in 24 hour wall clock time with 100 cores. c) Linearly scalable with number of cores. Tested with 1000 cores that produced data in 25 hrs for 10 flutter boundaries. Further wall-clock speed-up is possible by performing parallel computations within each case.

Laryngoscope plastic blades in scheduled general anesthesia patients: a comparative randomized study.

PubMed

Galinski, Michel; Catineau, Jean; Rayeh, Fatima; Muret, Jane; Ciebiera, Jean-Pierre; Plantevin, Frédéric; Foucrier, Arnaud; Tual, Loic; Combes, Xavier; Adnet, Frédéric

2011-03-01

To compare two brands of disposable plastic laryngoscope blades, Vital View plastic blades and Heine XP plastic blades, with the reusable Heine Classic+ Macintosh metal blades. Prospective randomized, controlled, single-blinded study. Operating room of a university-affiliated hospital. 519 patients without criteria for predicted difficult intubation, undergoing scheduled surgery during general anesthesia. Patients were randomized to three groups according to laryngoscope blade brand. Difficult tracheal intubation was evaluated by the Intubation Difficulty Scale (IDS) (IDS > 5 = procedure involving moderate to major difficulty). The percentage of intubations with an IDS > 5 was 3.1% in Group M (metal blade group), 5.1% in Group V (Vital View plastic blade group), and 10.0% in Group H (Heine plastic blade group). A significant difference was noted between Groups M and H (P = 0.02) but not between Groups M and V. Intubation may be more challenging when using Heine XP plastic blades but no significant difference exists between Vital-View plastic blades and Heine Classic+ metal blades. Copyright © 2011 Elsevier Inc. All rights reserved.

Device for sectioning prostatectomy specimens to facilitate comparison between histology and in vivo MRI

PubMed Central

Drew, Bryn; Jones, Edward C.; Reinsberg, Stefan; Yung, Andrew C.; Goldenberg, S. Larry; Kozlowski, Piotr

2012-01-01

Purpose To develop a device for sectioning prostatectomy specimens that would facilitate comparison between histology and in vivo MRI. Materials and methods A multi-bladed cutting device was developed, which consists of an adjustable box capable of accommodating a prostatectomy specimen up to 85 mm in size in the lateral direction, a “plunger” tool to press on the excised gland from the top to prevent it from rolling or sliding during sectioning, and a multi-bladed knife assembly capable of holding up to 21 blades at 4 mm intervals. The device was tested on a formalin fixed piece of meat and subsequently used to section a prostatectomy specimen. Histology sections were compared with T2-weighted MR images acquired in vivo prior to the prostatectomy procedure. Results The prostatectomy specimen slices were very uniform in thickness with each face parallel to the other with no visible sawing marks on the sections by the blades after the cut. MRI and histology comparison showed good correspondence between the two images. Conclusion The developed device allows sectioning of prostatectomy specimens into parallel cuts at a specific orientation and fixed intervals. Such a device is useful in facilitating accurate correlation between histology and MRI data. PMID:20882632

Manufacturing process modeling for composite materials and structures, Sandia blade reliability collaborative

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guest, Daniel A.; Cairns, Douglas S.

2014-02-01

The increased use and interest in wind energy over the last few years has necessitated an increase in the manufacturing of wind turbine blades. This increase in manufacturing has in many ways out stepped the current understanding of not only the materials used but also the manufacturing methods used to construct composite laminates. The goal of this study is to develop a list of process parameters which influence the quality of composite laminates manufactured using vacuum assisted resin transfer molding and to evaluate how they influence laminate quality. Known to be primary factors for the manufacturing process are resin flowmore » rate and vacuum pressure. An incorrect balance of these parameters will often cause porosity or voids in laminates that ultimately degrade the strength of the composite. Fiber waviness has also been seen as a major contributor to failures in wind turbine blades and is often the effect of mishandling during the lay-up process. Based on laboratory tests conducted, a relationship between these parameters and laminate quality has been established which will be a valuable tool in developing best practices and standard procedures for the manufacture of wind turbine blade composites.« less

Reduced-Order Blade Mistuning Analysis Techniques Developed for the Robust Design of Engine Rotors

NASA Technical Reports Server (NTRS)

Min, James B.

2004-01-01

The primary objective of this research program is to develop vibration analysis tools, design tools, and design strategies to significantly improve the safety and robustness of turbine engine rotors. Bladed disks in turbine engines always feature small, random blade-to-blade differences, or mistuning. Mistuning can lead to a dramatic increase in blade forced-response amplitudes and stresses. Ultimately, this results in high-cycle fatigue, which is a major safety and cost concern. In this research program, the necessary steps will be taken to transform a state-of-the-art vibration analysis tool, the Turbo-Reduce forced-response prediction code, into an effective design tool by enhancing and extending the underlying modeling and analysis methods. Furthermore, novel techniques will be developed to assess the safety of a given design. In particular, a procedure will be established for using eigenfrequency curve veerings to identify "danger zones" in the operating conditions--ranges of rotational speeds and engine orders in which there is a great risk that the rotor blades will suffer high stresses. This work also will aid statistical studies of the forced response by reducing the necessary number of simulations. Finally, new strategies for improving the design of rotors will be pursued. Several methods will be investigated, including the use of intentional mistuning patterns to mitigate the harmful effects of random mistuning, and the modification of disk stiffness to avoid reaching critical values of interblade coupling in the desired operating range. Recent research progress is summarized in the following paragraphs. First, significant progress was made in the development of the component mode mistuning (CMM) and static mode compensation (SMC) methods for reduced-order modeling of mistuned bladed disks (see the following figure). The CMM method has been formalized and extended to allow a general treatment of mistuning. In addition, CMM allows individual mode mistuning, which accounts for the realistic effects of local variations in blade properties that lead to different mistuning values for different mode types (e.g., mistuning of the first torsion mode versus the second flexural mode). The accuracy and efficiency of the CMM method and the corresponding Turbo-Reduce code were validated for an example finite element model of a bladed disk.

Efficient sensitivity analysis and optimization of a helicopter rotor

NASA Technical Reports Server (NTRS)

Lim, Joon W.; Chopra, Inderjit

1989-01-01

Aeroelastic optimization of a system essentially consists of the determination of the optimum values of design variables which minimize the objective function and satisfy certain aeroelastic and geometric constraints. The process of aeroelastic optimization analysis is illustrated. To carry out aeroelastic optimization effectively, one needs a reliable analysis procedure to determine steady response and stability of a rotor system in forward flight. The rotor dynamic analysis used in the present study developed inhouse at the University of Maryland is based on finite elements in space and time. The analysis consists of two major phases: vehicle trim and rotor steady response (coupled trim analysis), and aeroelastic stability of the blade. For a reduction of helicopter vibration, the optimization process requires the sensitivity derivatives of the objective function and aeroelastic stability constraints. For this, the derivatives of steady response, hub loads and blade stability roots are calculated using a direct analytical approach. An automated optimization procedure is developed by coupling the rotor dynamic analysis, design sensitivity analysis and constrained optimization code CONMIN.

Aeroelastic Stability of Rotor Blades Using Finite Element Analysis

NASA Technical Reports Server (NTRS)

Chopra, I.; Sivaneri, N.

1982-01-01

The flutter stability of flap bending, lead-lag bending, and torsion of helicopter rotor blades in hover is investigated using a finite element formulation based on Hamilton's principle. The blade is divided into a number of finite elements. Quasi-steady strip theory is used to evaluate the aerodynamic loads. The nonlinear equations of motion are solved for steady-state blade deflections through an iterative procedure. The equations of motion are linearized assuming blade motion to be a small perturbation about the steady deflected shape. The normal mode method based on the coupled rotating natural modes is used to reduce the number of equations in the flutter analysis. First the formulation is applied to single-load-path blades (articulated and hingeless blades). Numerical results show very good agreement with existing results obtained using the modal approach. The second part of the application concerns multiple-load-path blades, i.e. bearingless blades. Numerical results are presented for several analytical models of the bearingless blade. Results are also obtained using an equivalent beam approach wherein a bearingless blade is modelled as a single beam with equivalent properties. Results show the equivalent beam model.

A calculation procedure for viscous flow in turbomachines, volume 3. [computer programs

NASA Technical Reports Server (NTRS)

Khalil, I.; Sheoran, Y.; Tabakoff, W.

1980-01-01

A method for analyzing the nonadiabatic viscous flow through turbomachine blade passages was developed. The field analysis is based upon the numerical integration of the full incompressible Navier-Stokes equations, together with the energy equation on the blade-to-blade surface. A FORTRAN IV computer program was written based on this method. The numerical code used to solve the governing equations employs a nonorthogonal boundary fitted coordinate system. The flow may be axial, radial or mixed and there may be a change in stream channel thickness in the through-flow direction. The inputs required for two FORTRAN IV programs are presented. The first program considers laminar flows and the second can handle turbulent flows. Numerical examples are included to illustrate the use of the program, and to show the results that are obtained.

A study of pump cavitation damage

NASA Astrophysics Data System (ADS)

Brophy, M. C.; Stinebring, D. R.; Billet, M. L.

1983-11-01

The cavitation assessment for the space shuttle main engine high pressure oxidizer turbopump is documented. A model of the flow through the pump was developed. Initially, a computational procedure was used to analyze the flow through the inlet casing including the prediction of wakes downstream of the casing vanes. From these flow calculations, cavitation patterns on the inducer blades were approximated and the damage rate estimated. The model correlates the heavy damage on the housing and over the inducer with unsteady blade surface cavitation. The unsteady blade surface cavitation is due to the large incidence changes caused by the wakes of the upstream vanes. Very high cavitation damage rates are associated with this type of cavitation. Design recommendations for reducing the unsteady cavitation include removing the set of vanes closest to the inducer and modifying the remaining vanes.

Flap-Lag-Torsion Stability in Forward Flight

NASA Technical Reports Server (NTRS)

Panda, B.; Chopra, I.

1985-01-01

An aeroelastic stability of three-degree flap-lag-torsion blade in forward flight is examined. Quasisteady aerodynamics with a dynamic inflow model is used. The nonlinear time dependent periodic blade response is calculated using an iterative procedure based on Floquet theory. The periodic perturbation equations are solved for stability using Floquet transition matrix theory as well as constant coefficient approximation in the fixed reference frame. Results are presented for both stiff-inplane and soft-inplane blade configurations. The effects of several parameters on blade stability are examined, including structural coupling, pitch-flap and pitch-lag coupling, torsion stiffness, steady inflow distribution, dynamic inflow, blade response solution and constant coefficient approximation.

Helicopter vibration suppression using simple pendulum absorbers on the rotor blade

NASA Technical Reports Server (NTRS)

Hamouda, M.-N. H.; Pierce, G. A.

1981-01-01

A design procedure is presented for the installation of simple pendulums on the blades of a helicopter rotor to suppress the root reactions. The procedure consists of a frequency response analysis for a hingeless rotor blade excited by a harmonic variation of spanwise airload distributions during forward flight, as well as a concentrated load at the tip. The structural modeling of the blade provides for elastic degrees of freedom in flap and lead-lag bending plus torsion. Simple flap and lead-lag pendulums are considered individually. Using a rational order scheme, the general nonlinear equations of motion are linearized. A quasi-steady aerodynamic representation is used in the formation of the airloads. The solution of the system equations derives from their representation as a transfer matrix. The results include the effect of pendulum tuning on the minimization of the hub reactions.

Salvage of tibial pilon fractures using fusion of the ankle with a 90 degrees cannulated blade-plate: a preliminary report.

PubMed

Morgan, S J; Thordarson, D B; Shepherd, L E

1999-06-01

Six patients with ankle joint destruction and delayed metaphyseal union after tibial plafond fracture were surgically treated with tibiotalar arthrodesis and metaphyseal reconstruction, using a fixed-angle cannulated blade-plate. The procedure was performed through a posterior approach in five cases and a lateral approach in one case. The subtalar joint was preserved in all cases. Metaphyseal union and a stable arthrodesis were obtained in all cases without loss of fixation and with no mechanical failure of the blade-plate. Union was obtained in an average of 26 weeks. No secondary procedures were required to obtain union. All six patients were ambulatory at last follow-up. Stable internal fixation for simultaneous tibiotalar fusion and metaphyseal reconstruction can be achieved with a cannulated blade-plate while preserving the subtalar joint in complex plafond fractures.

The nonlinear instability in flap-lag of rotor blades in forward flight

NASA Technical Reports Server (NTRS)

Tong, P.

1971-01-01

The nonlinear flap-lag coupled oscillation of torsionally rigid rotor blades in forward flight is examined using a set of consistently derived equations by the asymptotic expansion procedure of multiple time scales. The regions of stability and limit cycle oscillation are presented. The roles of parametric excitation, nonlinear oscillation, and forced excitation played in the response of the blade are determined.

Micromachined cutting blade formed from {211}-oriented silicon

DOEpatents

Fleming, James G.; Sniegowski, Jeffry J.; Montague, Stephen

2003-09-09

A cutting blade is disclosed fabricated of micromachined silicon. The cutting blade utilizes a monocrystalline silicon substrate having a {211} crystalline orientation to form one or more cutting edges that are defined by the intersection of {211} crystalline planes of silicon with {111} crystalline planes of silicon. This results in a cutting blade which has a shallow cutting-edge angle .theta. of 19.5.degree.. The micromachined cutting blade can be formed using an anisotropic wet etching process which substantially terminates etching upon reaching the {111} crystalline planes of silicon. This allows multiple blades to be batch fabricated on a common substrate and separated for packaging and use. The micromachined cutting blade, which can be mounted to a handle in tension and optionally coated for increased wear resistance and biocompatibility, has multiple applications including eye surgery (LASIK procedure).

Micromachined cutting blade formed from {211}-oriented silicon

DOEpatents

Fleming, James G [Albuquerque, NM; Fleming, legal representative, Carol; Sniegowski, Jeffry J [Tijeras, NM; Montague, Stephen [Albuquerque, NM

2011-08-09

A cutting blade is disclosed fabricated of micromachined silicon. The cutting blade utilizes a monocrystalline silicon substrate having a {211} crystalline orientation to form one or more cutting edges that are defined by the intersection of {211} crystalline planes of silicon with {111} crystalline planes of silicon. This results in a cutting blade which has a shallow cutting-edge angle .theta. of 19.5.degree.. The micromachined cutting blade can be formed using an anisotropic wet etching process which substantially terminates etching upon reaching the {111} crystalline planes of silicon. This allows multiple blades to be batch fabricated on a common substrate and separated for packaging and use. The micromachined cutting blade, which can be mounted to a handle in tension and optionally coated for increased wear resistance and biocompatibility, has multiple applications including eye surgery (LASIK procedure).

A coupled aero-structural model of a HAWT blade for dynamic load and response prediction in time-domain for health monitoring applications

NASA Astrophysics Data System (ADS)

Sauder, Heather Scot

To reach the high standards set for renewable energy production in the US and around the globe, wind turbines with taller towers and longer blades are being designed for onshore and offshore wind developments to capture more energy from higher winds aloft and a larger rotor diameter. However, amongst all the wind turbine components wind turbine blades are still the most prone to damage. Given that wind turbine blades experience dynamic loads from multiple sources, there is a need to be able to predict the real-time load, stress distribution and response of the blade in a given wind environment for damage, flutter and fatigue life predictions. Current methods of wind-induced response analysis for wind turbine blades use approximations that are not suitable for wind turbine blade airfoils which are thick, and therefore lead to inaccurate life predictions. Additionally, a time-domain formulation can prove to be especially advantageous for predicting aerodynamic loads on wind turbine blades since they operate in a turbulent atmospheric boundary layer. This will help to analyze the blades on wind turbines that operate individually or in a farm setting where they experience high turbulence in the wake of another wind turbine. A time-domain formulation is also useful for examining the effects of gusty winds that are transient in nature like in gust fronts, thunderstorms or extreme events such as hurricanes, microbursts, and tornadoes. Time-domain methods present the opportunity for real-time health monitoring strategies that can easily be used with finite element methods for prediction of fatigue life or onset of flutter instability. The purpose of the proposed work is to develop a robust computational model to predict the loads, stresses and response of a wind turbine blade in operating and extreme wind conditions. The model can be used to inform health monitoring strategies for preventative maintenance and provide a realistic number of stress cycles that the blade will experience for fatigue life prediction procedures. To fill in the gaps in the existing knowledge and meet the overall goal of the proposed research, the following objectives were accomplished: (a) improve the existing aeroelastic (motion- and turbulence-induced) load models to predict the response of wind turbine blade airfoils to understand its behavior in turbulent wind, (b) understand, model and predict the response of wind turbine blades in transient or gusty wind, boundary-layer wind and incoherent wind over the span of the blade, (c) understand the effects of aero-structural coupling between the along-wind, cross-wind and torsional vibrations, and finally (d) develop a computational tool using the improved time-domain load model to predict the real-time load, stress distribution and response of a given wind turbine blade during operating and parked conditions subject to a specific wind environment both in a short and long term for damage, flutter and fatigue life predictions.

Study on Design of High Efficiency and Light Weight Composite Propeller Blade for a Regional Turboprop Aircraft

NASA Astrophysics Data System (ADS)

Kong, Changduk; Lee, Kyungsun

2013-03-01

In this study, aerodynamic and structural design of the composite propeller blade for a regional turboprop aircraft is performed. The thin and wide chord propeller blade of high speed turboprop aircraft should have proper strength and stiffness to carry various kinds of loads such as high aerodynamic bending and twisting moments and centrifugal forces. Therefore the skin-spar-foam sandwich structure using high strength and stiffness carbon/epoxy composite materials is used to improve the lightness. A specific design procedure is proposed in this work as follows; firstly the aerodynamic configuration design, which is acceptable for the design requirements, is carried out using the in-house code developed by authors, secondly the structure design loads are determined through the aerodynamic load case analysis, thirdly the spar flange and the skin are preliminarily sized by consideration of major bending moments and shear forces using both the netting rule and the rule of mixture, and finally, the stress analysis is performed to confirm the structural safety and stability using finite element analysis commercial code, MSC. NASTRAN/PATRAN. Furthermore the additional analysis is performed to confirm the structural safety due to bird strike impact on the blade during flight operation using a commercial code, ANSYS. To realize the proposed propeller design, the prototype blades are manufactured by the following procedure; the carbon/epoxy composite fabric prepregs are laid up for skin and spar on a mold using the hand lay-up method and consolidated with a proper temperature and vacuum in the oven. To finalize the structural design, the full-scale static structural test is performed under the simulated aerodynamic loads using 3 point loading method. From the experimental results, it is found that the designed blade has a good structural integrity, and the measured results agree well with the analytical results as well.

Evaluation of Bacterial Contamination of Clipper Blades in Small Animal Private Practice.

PubMed

Mount, Rebecca; Schick, Anthea E; Lewis, Thomas P; Newton, Heide M

2016-01-01

Nosocomial infections are a growing concern in veterinary hospitals, and identifying fomites is imperative to reducing the risk of pathogen transmission. In veterinary medicine, shaving of hair is necessary prior to many procedures. Contaminated clipper blades have been cited as potential fomites involved in the transmission of pathogens in veterinary and human medicine. The primary goal of this study was to evaluate bacterial contamination of clipper blades in veterinary practices. A secondary goal was to assess whether there was an association between bacterial contamination of clipper blades and clipper blade cleaning solutions, clipper blade cleaning protocols, clipper blade storage, and type of practice. Sixty clipper blades from 60 different practices were cultured. Information regarding blade cleaning solutions, protocols, and storage was collected from each practice. Fifty-one percent (31/60) of clipper blades sampled were contaminated with bacteria. Category of cleaning solutions had a significant association with bacterial contamination (P < 0.02). Cleaning frequency (P = 0.55), storage location (P = 0.26), and practice type (P = 0.06) had no significant association with bacterial contamination. This study documented bacterial contamination of clipper blades in veterinary practices, and clipper blades should be considered potential fomites.

Determination of the performance of the Kaplan hydraulic turbines through simplified procedure

NASA Astrophysics Data System (ADS)

Pădureanu, I.; Jurcu, M.; Campian, C. V.; Haţiegan, C.

2018-01-01

A simplified procedure has been developed, compared to the complex one recommended by IEC 60041 (i.e. index samples), for measurement of the performance of the hydraulic turbines. The simplified procedure determines the minimum and maximum powers, the efficiency at maximum power, the evolution of powers by head and flow and to determine the correct relationship between runner/impeller blade angle and guide vane opening for most efficient operation of double-regulated machines. The simplified procedure can be used for a rapid and partial estimation of the performance of hydraulic turbines for repair and maintenance work.

Improving Bending Moment Measurements on Wind Turbine Blades

DOE Office of Scientific and Technical Information (OSTI.GOV)

Post, Nathan L.

Full-scale fatigue testing of wind turbine blades is conducted using resonance test techniques where the blade plus additional masses is excited at its first resonance frequency to achieve the target loading amplitude. Because there is not a direct relationship between the force applied by an actuator and the bending moment, the blade is instrumented with strain gauges that are calibrated under static loading conditions to determine the sensitivity or relationship between strain and applied moment. Then, during dynamic loading the applied moment is calculated using the strain response of the structure. A similar procedure is also used in the fieldmore » to measure in-service loads on turbine blades. Because wind turbine blades are complex twisted structures and the deflections are large, there is often significant cross-talk coupling in the sensitivity of strain gauges placed on the structure. Recent work has shown that a sensitivity matrix with nonzero cross terms must be employed to find constant results when a blade is subjected to both flap and lead-lag loading. However, even under controlled laboratory conditions, potential for errors of 3 percent or more in the measured moment exist when using the typical cross-talk matrix approach due to neglecting the influence of large deformations and torsion. This is particularly critical when considering a biaxial load as would be applied on the turbine or during a biaxial fatigue test. This presentation describes these results demonstrating errors made when performing current loads measurement practices on wind turbine blades in the lab and evaluating potential improvements using enhanced cross-talk matrix approaches and calibration procedures.« less

Rotating Shake Test and Modal Analysis of a Model Helicopter Rotor Blade

NASA Technical Reports Server (NTRS)

Wilkie, W. Keats; Mirick, Paul H.; Langston, Chester W.

1997-01-01

Rotating blade frequencies for a model generic helicopter rotor blade mounted on an articulated hub were experimentally determined. Testing was conducted using the Aeroelastic Rotor Experimental System (ARES) testbed in the Helicopter Hover Facility (HBF) at Langley Research Center. The measured data were compared to pretest analytical predictions of the rotating blade frequencies made using the MSC/NASTRAN finite-element computer code. The MSC/NASTRAN solution sequences used to analyze the model were modified to account for differential stiffening effects caused by the centrifugal force acting on the blade and rotating system dynamic effects. The correlation of the MSC/NASTRAN-derived frequencies with the experimental data is, in general, very good although discrepancies in the blade torsional frequency trends and magnitudes were observed. The procedures necessary to perform a rotating system modal analysis of a helicopter rotor blade with MSC/NASTRAN are outlined, and complete sample data deck listings are provided.

Turbine Blade Temperature Measurements Using Thin Film Temperature Sensors

NASA Technical Reports Server (NTRS)

Grant, H. P.; Przybyszewski, J. S.; Claing, R. G.

1981-01-01

The development of thin film temperature sensors is discussed. The technology for sputtering 2 micron thin film platinum versus platinum 10 percent rhodium thermocouples on alumina forming coatings was improved and extended to applications on actual turbine blades. Good adherence was found to depend upon achieving a proper morphology of the alumina surface. Problems of adapting fabrication procedures to turbine blades were uncovered, and improvements were recommended. Testing at 1250 K at one atmosphere pressure was then extended to a higher Mach No. (0.5) in combustor flow for 60 hours and 71 thermal cycles. The mean time to failure was 47 hours accumulated during 1 hour exposures in the combustor. Calibration drift was about 0.1 percent per hour, attributable to oxidation of the rhodium in the thin films. An increase in film thickness and application of a protective overcoat are recommended to reduce drift in actual engine testing.

Ribbon curling

NASA Astrophysics Data System (ADS)

Juel, Anne; Prior, Chris; Moussou, Julien; Chakrabarti, Buddhapriya; Jensen, Oliver

The procedure of curling a ribbon by running it over a sharp blade is commonly used when wrapping presents. Despite its ubiquity, a quantitative explanation of this everyday phenomenon is still lacking. We address this using experiment and theory, examining the dependence of ribbon curvature on blade curvature, the longitudinal load imposed on the ribbon and the speed of pulling. Experiments in which a ribbon is drawn steadily over a blade under a fixed load show that the ribbon curvature is generated over a restricted range of loads, the curvature/load relationship can be non-monotonic, and faster pulling (under a constant imposed load) results in less tightly curled ribbons. We develop a theoretical model that captures these features, building on the concept that the ribbon under the imposed deformation undergoes differential plastic stretching across its thickness, resulting in a permanently curved shape. The model identifies factors that optimize curling and clarifies the physical mechanisms underlying the ribbon's nonlinear response to an apparently simple deformation.

An analysis of pump cavitation damage. [Space Shuttle main engine high pressure oxidizer turbopump

NASA Technical Reports Server (NTRS)

Brophy, M. C.; Stinebring, D. R.; Billet, M. L.

1985-01-01

The cavitation assessment for the space shuttle main engine high pressure oxidizer turbopump is documented. A model of the flow through the pump was developed. Initially, a computational procedure was used to analyze the flow through the inlet casing including the prediction of wakes downstream of the casing vanes. From these flow calculations, cavitation patterns on the inducer blades were approximated and the damage rate estimated. The model correlates the heavy damage on the housing and over the inducer with unsteady blade surface cavitation. The unsteady blade surface cavitation is due to the large incidence changes caused by the wakes of the upstream vanes. Very high cavitation damage rates are associated with this type of cavitation. Design recommendations for reducing the unsteady cavitation include removing the set of vanes closest to the inducer and modifying the remaining vanes.

A study of pump cavitation damage. [space shuttle main engine high pressure oxidizer turbopump

NASA Technical Reports Server (NTRS)

Brophy, M. C.; Stinebring, D. R.; Billet, M. L.

1983-01-01

The cavitation assessment for the space shuttle main engine high pressure oxidizer turbopump is documented. A model of the flow through the pump was developed. Initially, a computational procedure was used to analyze the flow through the inlet casing including the prediction of wakes downstream of the casing vanes. From these flow calculations, cavitation patterns on the inducer blades were approximated and the damage rate estimated. The model correlates the heavy damage on the housing and over the inducer with unsteady blade surface cavitation. The unsteady blade surface cavitation is due to the large incidence changes caused by the wakes of the upstream vanes. Very high cavitation damage rates are associated with this type of cavitation. Design recommendations for reducing the unsteady cavitation include removing the set of vanes closest to the inducer and modifying the remaining vanes.

Long-term strength determination for cooled blades made of monocrystalline superalloys

NASA Astrophysics Data System (ADS)

Getsov, L. B.; Semenov, A. S.; Besschetnov, V. A.; Grishchenko, A. I.; Semenov, S. G.

2017-04-01

For the manufacture of blades for modern gas-turbine installations, monocrystalline alloys are used. Traditional methods for the calculation of stressed-deformed state and safety factors for these alloys developed and verified for polycrystalline materials need to be adjusted. This paper deals with methodological principles for an approach to the solving of the problem concerning a finite-element determination of the long-term static strength for cooled monocrystalline blades employed in gas-turbine installations based on the use of two different models (phenomenological and micromechanical) considering the inelastic deformation of monocrystalline superalloys. An analysis has been performed for the distribution of Schmid factors in the spherical triangle for primary and secondary octahedral and cubic slip systems. Calculations are performed using Larson-Miller's parametric dependences taking into account the crystallographic orientation of the material. A determination procedure for the anisotropy coefficients of long-term strength is described based on data for different orientations. A comparative analysis of the results of finite-element calculations made using phenomenological and micromechanical (crystallographic) creep models for the long-term static strength of cooled monocrystalline blades used in a gas-turbine engine has been performed. It is shown that the location of the most loaded sections of such a blade coincide with the results of calculations according to these models. It has been found that the micromechanical deformation model results in the obtaining of the most conservative estimate for the long-term strength of turbine blades made of monocrystalline alloys. It is shown that the calculations using models for materials with isotropic properties can produce considerable errors in determining the durability of the blades. The possibility is considered for using 1D-, 2D-, and 3D-models for turbine monocrystalline blades in the determination of their durability parameters.

Effects of Transducer Installation on Unsteady Pressure Measurements on Oscillating Blades

NASA Technical Reports Server (NTRS)

Lepicovsky, Jan

2006-01-01

Unsteady pressures were measured above the suction side of a blade that was oscillated to simulate blade stall flutter. Measurements were made at blade oscillation frequencies up to 500 Hz. Two types of miniature pressure transducers were used: surface-mounted flat custom-made, and conventional miniature, body-mounted transducers. The signals of the surface-mounted transducers are significantly affected by blade acceleration, whereas the signals of body-mounted transducers are practically free of this distortion. A procedure was introduced to correct the signals of surface-mounted transducers to rectify the signal distortion due to blade acceleration. The signals from body-mounted transducers, and corrected signals from surface-mounted transducers represent true unsteady pressure signals on the surface of a blade subjected to forced oscillations. However, the use of body-mounted conventional transducers is preferred for the following reasons: no signal corrections are needed for blade acceleration, the conventional transducers are noticeably less expensive than custom-made flat transducers, the survival rate of body-mounted transducers is much higher, and finally installation of body-mounted transducers does not disturb the blade surface of interest.

Data Reduction Procedures for Laser Velocimeter Measurements in Turbomachinery Rotors

NASA Technical Reports Server (NTRS)

Lepicovsky, Jan

1994-01-01

Blade-to-blade velocity distributions based on laser velocimeter data acquired in compressor or fan rotors are increasingly used as benchmark data for the verification and calibration of turbomachinery computational fluid dynamics (CFD) codes. Using laser Doppler velocimeter (LDV) data for this purpose, however, must be done cautiously. Aside from the still not fully resolved issue of the seed particle response in complex flowfields, there is an important inherent difference between CFD predictions and LDV blade-to-blade velocity distributions. CFD codes calculate velocity fields for an idealized rotor passage. LDV data, on the other hand, stem from the actual geometry of all blade channels in a rotor. The geometry often varies from channel to channel as a result of manufacturing tolerances, assembly tolerances, and incurred operational damage or changes in the rotor individual blades.

Computer code for off-design performance analysis of radial-inflow turbines with rotor blade sweep

NASA Technical Reports Server (NTRS)

Meitner, P. L.; Glassman, A. J.

1983-01-01

The analysis procedure of an existing computer program was extended to include rotor blade sweep, to model the flow more accurately at the rotor exit, and to provide more detail to the loss model. The modeling changes are described and all analysis equations and procedures are presented. Program input and output are described and are illustrated by an example problem. Results obtained from this program and from a previous program are compared with experimental data.

The design and development of transonic multistage compressors

NASA Technical Reports Server (NTRS)

Ball, C. L.; Steinke, R. J.; Newman, F. A.

1988-01-01

The development of the transonic multistage compressor is reviewed. Changing trends in design and performance parameters are noted. These changes are related to advances in compressor aerodynamics, computational fluid mechanics and other enabling technologies. The parameters normally given to the designer and those that need to be established during the design process are identified. Criteria and procedures used in the selection of these parameters are presented. The selection of tip speed, aerodynamic loading, flowpath geometry, incidence and deviation angles, blade/vane geometry, blade/vane solidity, stage reaction, aerodynamic blockage, inlet flow per unit annulus area, stage/overall velocity ratio, and aerodynamic losses are considered. Trends in these parameters both spanwise and axially through the machine are highlighted. The effects of flow mixing and methods for accounting for the mixing in the design process are discussed.

Two-Equation Low-Reynolds-Number Turbulence Modeling of Transitional Boundary Layer Flows Characteristic of Gas Turbine Blades. Ph.D. Thesis. Final Contractor Report

NASA Technical Reports Server (NTRS)

Schmidt, Rodney C.; Patankar, Suhas V.

1988-01-01

The use of low Reynolds number (LRN) forms of the k-epsilon turbulence model in predicting transitional boundary layer flow characteristic of gas turbine blades is developed. The research presented consists of: (1) an evaluation of two existing models; (2) the development of a modification to current LRN models; and (3) the extensive testing of the proposed model against experimental data. The prediction characteristics and capabilities of the Jones-Launder (1972) and Lam-Bremhorst (1981) LRN k-epsilon models are evaluated with respect to the prediction of transition on flat plates. Next, the mechanism by which the models simulate transition is considered and the need for additional constraints is discussed. Finally, the transition predictions of a new model are compared with a wide range of different experiments, including transitional flows with free-stream turbulence under conditions of flat plate constant velocity, flat plate constant acceleration, flat plate but strongly variable acceleration, and flow around turbine blade test cascades. In general, calculational procedure yields good agreement with most of the experiments.

Experimental determination of transient strain in a thermally-cycled simulated turbine blade utilizing a non-contact technique

NASA Technical Reports Server (NTRS)

Calfo, F. D.; Bizon, P. T.

1978-01-01

A type of noncontacting electro-optical extensometer was used to measure the displacement between parallel targets mounted on the leading edge of a simulated turbine blade throughout a complete heating and cooling cycle. The blade was cyclically heated and cooled by moving it into and out of a Mach 1 hot gas stream. The principle of operation and measurement procedure of the electro-optics extensometer are described.

Test Operations Procedure (TOP) 01-2-603 Rotorcraft Laboratory Vibration Test Schedules

DTIC Science & Technology

2017-06-12

for all rotary wing aircraft platforms. Tonal amplitudes are tabular based solely on engine revolutions per minute (RPM) and blade count. (4...Power Spectral Density (PSD) format with superimposed sinusoidal components that are associated with the rotor speeds and blade count of each...harmonics are not limited to the 3rd harmonic of the blade passage as in MIL-STD- TOP 01-2-603 12 June 2017 5 810. In addition, attempts were

Design of thin shear blades for crosscut shearing of wood.

Treesearch

Rodger A. Arola; Thomas R. Grimm

1974-01-01

Discusses principles and presents formulations for evaluating the elastic stability of thin plates subjected to edge loadings. Three different prestress methods to increase late stability are presented. A procedure is given to evaluate the elastic stability of thin shear blades under expected shearing loads.

Method to improve the blade tip-timing accuracy of fiber bundle sensor under varying tip clearance

NASA Astrophysics Data System (ADS)

Duan, Fajie; Zhang, Jilong; Jiang, Jiajia; Guo, Haotian; Ye, Dechao

2016-01-01

Blade vibration measurement based on the blade tip-timing method has become an industry-standard procedure. Fiber bundle sensors are widely used for tip-timing measurement. However, the variation of clearance between the sensor and the blade will bring a tip-timing error to fiber bundle sensors due to the change in signal amplitude. This article presents methods based on software and hardware to reduce the error caused by the tip clearance change. The software method utilizes both the rising and falling edges of the tip-timing signal to determine the blade arrival time, and a calibration process suitable for asymmetric tip-timing signals is presented. The hardware method uses an automatic gain control circuit to stabilize the signal amplitude. Experiments are conducted and the results prove that both methods can effectively reduce the impact of tip clearance variation on the blade tip-timing and improve the accuracy of measurements.

Investigation of two-stage air-cooled turbine suitable for flight at Mach number of 2.5 II : blade design

NASA Technical Reports Server (NTRS)

Miser, James W; Stewart, Warner L

1957-01-01

A blade design study is presented for a two-stage air-cooled turbine suitable for flight at a Mach number of 2.5 for which velocity diagrams have been previously obtained. The detailed procedure used in the design of the blades is given. In addition, the design blade shapes, surface velocity distributions, inner and outer wall contours, and other design data are presented. Of all the blade rows, the first-stage rotor has the highest solidity, with a value of 2.289 at the mean section. The second-stage stator also had a high mean-section solidity of 1.927, mainly because of its high inlet whirl. The second-stage rotor has the highest value of the suction-surface diffusion parameter, with a value of 0.151. All other blade rows have values for this parameter under 0.100.

Hub and blade structural loads measurements of an SA349/2 helicopter

NASA Technical Reports Server (NTRS)

Yamauchi, Gloria K.; Heffernan, Ruth M.; Gaubert, Michel

1988-01-01

Data from 23 flight conditions, including level flights ranging from advance ratio mu = 0.14 to 0.37 and steady turning flights from advance ratio mu = 0.26 to 0.35, are presented for an Aerospatiale SA349/2 Gazelle helicopter. The data include hub loads data (for 6 of the 23 conditions), blade structural data at eleven different blade radial stations, and fuselage structural data. All dynamic data are presented as harmonic analysis coefficients (ten harmonics per rotor revolution). The data acquisition and reduction procedures are also documented. Blade structural and inertial properties are provided in addition to control system geometry and properties.

Summary of design and blade-element performance data for 12 axial-flow pump rotor configurations

NASA Technical Reports Server (NTRS)

Miller, M. J.; Okiishi, T. H.; Serovy, G. K.; Sandercock, D. M.; Britsch, W. R.

1973-01-01

A collection of noncavitating blade-element performance data for 12 axial-flow pump rotor configurations is presented in tabular form. Rotor design philosophy, test apparatus and procedure, and data reduction and evaluation are discussed. A data storage and recall computer program is described. All but one of the rotor configurations considered were composed of double-circular-arc blade sections and were designed for high inlet relative flow angles. Hub-tip radius ranged from 0.40 to 0.90.

Detailed computational procedure for design of cascade blades with prescribed velocity distributions in compressible potential flows

NASA Technical Reports Server (NTRS)

Costello, George R; Cummings, Robert L; Sinnette, John T , Jr

1952-01-01

A detailed step-by-step computational outline is presented for the design of two-dimensional cascade blades having a prescribed velocity distribution on the blade in a potential flow of the usual compressible fluid. The outline is based on the assumption that the magnitude of the velocity in the flow of the usual compressible nonviscous fluid is proportional to the magnitude of the velocity in the flow of a compressible nonviscous fluid with linear pressure-volume relation.

Acoustic measurements from a rotor blade-vortex interaction noise experiment in the German-Dutch Wind Tunnel (DNW)

NASA Technical Reports Server (NTRS)

Martin, Ruth M.; Splettstoesser, W. R.; Elliott, J. W.; Schultz, K.-J.

1988-01-01

Acoustic data are presented from a 40 percent scale model of the 4-bladed BO-105 helicopter main rotor, measured in the large European aeroacoustic wind tunnel, the DNW. Rotor blade-vortex interaction (BVI) noise data in the low speed flight range were acquired using a traversing in-flow microphone array. The experimental apparatus, testing procedures, calibration results, and experimental objectives are fully described. A large representative set of averaged acoustic signals is presented.

Materials, Manufacturing and Test Development of a Composite Fan Blade Leading Edge Subcomponent for Improved Impact Resistance

NASA Technical Reports Server (NTRS)

Handschuh, Katherine M.; Miller, Sandi G.; Sinnott, Matthew J.; Kohlman, Lee W.; Roberts, Gary D.; Pereira, J. Michael; Ruggeri, Charles R.

2014-01-01

Application of polymer matrix composite materials for jet engine fan blades is becoming attractive as an alternative to metallic blades; particularly for large engines where significant weight savings are recognized on moving to a composite structure. However, the weight benefit of the composite of is offset by a reduction of aerodynamic efficiency resulting from a necessary increase in blade thickness; relative to the titanium blades. Blade dimensions are largely driven by resistance to damage on bird strike. Further development of the composite material is necessary to allow composite blade designs to approximate the dimensions of a metallic fan blade. The reduction in thickness over the state of the art composite blades is expected to translate into structural weight reduction, improved aerodynamic efficiency, and therefore reduced fuel consumption. This paper presents test article design, subcomponent blade leading edge fabrication, test method development, and initial results from ballistic impact of a gelatin projectile on the leading edge of composite fan blades. The simplified test article geometry was developed to realistically simulate a blade leading edge while decreasing fabrication complexity. Impact data is presented on baseline composite blades and toughened blades; where a considerable improvement to impact resistance was recorded.

Materials, Manufacturing, and Test Development of a Composite Fan Blade Leading Edge Subcomponent for Improved Impact Resistance

NASA Technical Reports Server (NTRS)

Miller, Sandi G.; Handschuh, Katherine; Sinnott, Matthew J.; Kohlman, Lee W.; Roberts, Gary D.; Martin, Richard E.; Ruggeri, Charles R.; Pereira, J. Michael

2015-01-01

Application of polymer matrix composite materials for jet engine fan blades is becoming attractive as an alternative to metallic blades; particularly for large engines where significant weight savings are recognized on moving to a composite structure. However, the weight benefit of the composite is offset by a reduction of aerodynamic efficiency resulting from a necessary increase in blade thickness; relative to the titanium blades. Blade dimensions are largely driven by resistance to damage on bird strike. Further development of the composite material is necessary to allow composite blade designs to approximate the dimensions of a metallic fan blade. The reduction in thickness over the state of the art composite blades is expected to translate into structural weight reduction, improved aerodynamic efficiency, and therefore reduced fuel consumption. This paper presents test article design, subcomponent blade leading edge fabrication, test method development, and initial results from ballistic impact of a gelatin projectile on the leading edge of composite fan blades. The simplified test article geometry was developed to realistically simulate a blade leading edge while decreasing fabrication complexity. Impact data is presented on baseline composite blades and toughened blades; where a considerable improvement to impact resistance was recorded.

Estimation of blade airloads from rotor blade bending moments

NASA Technical Reports Server (NTRS)

Bousman, William G.

1987-01-01

This paper presents a method for the estimation of blade airloads, based on the measurements of flap bending moments. In this procedure, the blade rotation in vacuum modes is calculated, and the airloads are expressed as an algebraic sum of the mode shapes, modal amplitudes, mass distribution, and frequency properties. The method was validated by comparing the calculated airload distribution with the original wind tunnel measurements which were made using ten modes and twenty measurement stations. Good agreement between the predicted and the measured airloads was found up to 0.90 R, but the agreement degraded towards the blade tip. The method is shown to be quite robust to the type of experimental problems that could be expected to occur in the testing of full-scale and model-scale rotors.

Observed acoustic and aeroelastic spectral responses of a MOD-2 turbine blade to turbulence excitation

NASA Technical Reports Server (NTRS)

Kelley, N. D.; Mckenna, H. E.; Jacobs, E. W.

1995-01-01

Early results from a recent experiment designed to directly evaluate the aeroacoustic/elastic spectral responses of a MOD-2 turbine blade to turbulence-induced unsteady blade loads are discussed. The experimental procedure consisted of flying a hot-film anemometer from a tethered balloon in the turbine inflow and simultaneously measuring the fluctuating airload and aeroelastic response at two blade span stations (65% and 87% spans) using surface-mounted, subminiature pressure transducers and standard strain gage instrumentation. The radiated acoustic pressure field was measured with a triad of very-low-frequency microphones placed at ground level, 1.5 rotor diameters upwind of the disk. Initial transfer function estimates for acoustic radiation, blade normal forces, flapwise acceleration/displacement, and chord/flapwise moments are presented.

Computer program for definition of transonic axial-flow compressor blade rows

NASA Technical Reports Server (NTRS)

Crouse, J. E.

1975-01-01

Particular type of blade element used has two segments which have centerlines and surfaces described by constant change of angle with path distance on cone. Program is result of rework of earlier program to give major gains in accuracy, reliability and speed. It also covers more steps of overall compressor design procedure.

78 FR 64421 - Airworthiness Directives; Pratt & Whitney Canada Corp. Turboprop Engines

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-29

... borescope inspections (BSIs) of CT blades, and the removal from service of blades that fail inspection. We... approve AMOCs to this AD. Use the procedures found in 14 CFR 39.19 to make your request. (j) Related...://www.regulations.gov and follow the instructions for sending your comments electronically. Mail: Docket...

Ribbon curling via stress relaxation in thin polymer films

PubMed Central

Prior, Chris; Moussou, Julien; Chakrabarti, Buddhapriya

2016-01-01

The procedure of curling a ribbon by running it over a sharp blade is commonly used when wrapping presents. Despite its ubiquity, a quantitative explanation of this everyday phenomenon is still lacking. We address this using experiment and theory, examining the dependence of ribbon curvature on blade curvature, the longitudinal load imposed on the ribbon, and the speed of pulling. Experiments in which a ribbon is drawn steadily over a blade under a fixed load show that the ribbon curvature is generated over a restricted range of loads, the curvature/load relationship can be nonmonotonic, and faster pulling (under a constant imposed load) results in less tightly curled ribbons. We develop a theoretical model that captures these features, building on the concept that the ribbon under the imposed deformation undergoes differential plastic stretching across its thickness, resulting in a permanently curved shape. The model identifies factors that optimize curling and clarifies the physical mechanisms underlying the ribbon’s nonlinear response to an apparently simple deformation. PMID:26831118

DSAEK: practical approach to choose the microkeratome head on the basis of donor cornea pachymetry.

PubMed

Wisse, Robert P L; Achterberg, Jens A; Van der Lelij, Allegonda

2014-03-01

The aim of this study was to supply data on the relationship between Descemet stripping automated endothelial keratoplasty (DSAEK) graft thickness and its effects on visual acuity (VA), pace of visual recovery, endothelial cell densities (ECDs), and surgical complications. We additionally provide an approach for choosing the microkeratome blade thickness when multiple patients are scheduled for DSAEK. This is a retrospective analysis of all DSAEK procedures performed at our institute from January 2011 to December 2012. The VA was assessed at all postop visits. The ECD was assessed at 6 and 12 months postoperatively. An algorithm based on donor cornea pachymetry was used to assist in the choice of a microkeratome blade either 350 or 400 μm thick. Two groups were created on the basis of the microkeratome blade chosen. Outcomes were given per treatment group. One hundred two consecutive DSAEK procedures were performed; 60 grafts were prepared with the 350-μm blade and 39 with the 400-μm blade. Baseline characteristics did not differ materially. Grafts dissected using the 350-μm knife were significantly thicker than the grafts dissected with the 400-μm blade, with values of 257 ± 47 μm and 222 ± 33 μm, respectively (P = 0.01). The pace of visual recovery, VA at maximum follow-up, and ECD did not differ significantly between groups. Surgical complications were evenly distributed over both groups. This study indicates that using neither the 350-μm nor 400-μm microkeratome blade for the DSAEK altered the outcomes in terms of VA, ECD, and surgical complications. The algorithm presented in this study is helpful in equally distributing benefits from thinner grafting for all DSAEK-operated patients.

Minimum weight design of helicopter rotor blades with frequency constraints

NASA Technical Reports Server (NTRS)

Chattopadhyay, Aditi; Walsh, Joanne L.

1989-01-01

The minimum weight design of helicopter rotor blades subject to constraints on fundamental coupled flap-lag natural frequencies has been studied in this paper. A constraint has also been imposed on the minimum value of the blade autorotational inertia to ensure that the blade has sufficient inertia to autorotate in case of an engine failure. The program CAMRAD has been used for the blade modal analysis and the program CONMIN has been used for the optimization. In addition, a linear approximation analysis involving Taylor series expansion has been used to reduce the analysis effort. The procedure contains a sensitivity analysis which consists of analytical derivatives of the objective function and the autorotational inertia constraint and central finite difference derivatives of the frequency constraints. Optimum designs have been obtained for blades in vacuum with both rectangular and tapered box beam structures. Design variables include taper ratio, nonstructural segment weights and box beam dimensions. The paper shows that even when starting with an acceptable baseline design, a significant amount of weight reduction is possible while satisfying all the constraints for blades with rectangular and tapered box beams.

Successful Solutions to SSME/AT Development Turbine Blade Distress

NASA Technical Reports Server (NTRS)

Montgomery, Stuart K.

1999-01-01

As part of the High-Pressure Fuel Turbopump/Alternate Turbopump (HPFTP/AT) turbine blade development program, unique turbine blade design features were implemented to address 2nd stage turbine blade high cycle fatigue distress and improve turbine robustness. Features included the addition of platform featherseal dampers, asymmetric blade tip seal segments, gold plating of the blade attachments, and airfoil tip trailing edge modifications. Development testing shows these features have eliminated turbine blade high cycle fatigue distress and consequently these features are currently planned for incorporation to the flight configuration. Certification testing will begin in 1999. This presentation summarizes these features.

A flight investigation of basic performance characteristics of a teetering-rotor attack helicopter

NASA Technical Reports Server (NTRS)

Morris, C. E. K., Jr.

1979-01-01

Flight data were obtained with an instrumented AH-16 helicopter having uninstrumented, standard main-rotor blades. The data are presented to facilitate the analysis of data taken when the same vehicle was flown with instrumented main-rotor blades built with new airfoils. Test results include data on performance, flight-state parameters, pitch-link loads and blade angles for level flight, descending turns and pull-ups. Flight test procedures and the effects of both trim variations and transient phenomena on the data are discussed.

Fully three-dimensional and viscous semi-inverse method for axial/radial turbomachine blade design

NASA Astrophysics Data System (ADS)

Ji, Min

2008-10-01

A fully three-dimensional viscous semi-inverse method for the design of turbomachine blades is presented in this work. Built on a time marching Reynolds-Averaged Navier-Stokes solver, the inverse scheme is capable of designing axial/radial turbomachinery blades in flow regimes ranging from very low Mach number to transonic/supersonic flows. In order to solve flow at all-speed conditions, the preconditioning technique is incorporated into the basic JST time-marching scheme. The accuracy of the resulting flow solver is verified with documented experimental data and commercial CFD codes. The level of accuracy of the flow solver exhibited in those verification cases is typical of CFD analysis employed in the design process in industry. The inverse method described in the present work takes pressure loading and blade thickness as prescribed quantities and computes the corresponding three-dimensional blade camber surface. In order to have the option of imposing geometrical constraints on the designed blade shapes, a new inverse algorithm is developed to solve the camber surface at specified spanwise pseudo stream-tubes (i.e. along grid lines), while the blade geometry is constructed through ruling (e.g. straight-line element) at the remaining spanwise stations. The new inverse algorithm involves re-formulating the boundary condition on the blade surfaces as a hybrid inverse/analysis boundary condition, preserving the full three-dimensional nature of the flow. The new design procedure can be interpreted as a fully three-dimensional viscous semi-inverse method. The ruled surface design ensures the blade surface smoothness and mechanical integrity as well as achieves cost reduction for the manufacturing process. A numerical target shooting experiment for a mixed flow impeller shows that the semi-inverse method is able to accurately recover the target blade composed of straightline element from a different initial blade. The semi-inverse method is proved to work well with various loading strategies for the mixed flow impeller. It is demonstrated that uniformity of impeller exit flow and performance gain can be achieved with appropriate loading combinations at hub and shroud. An application of this semi-inverse method is also demonstrated through a redesign of an industrial shrouded subsonic centrifugal impeller. The redesigned impeller shows improved performance and operating range from the original one. Preliminary studies of blade designs presented in this work show that through the choice of the prescribed pressure loading profiles, this semi-inverse method can be used to design blade with the following objectives: (1) Various operating envelope. (2) Uniformity of impeller exit flow. (3) Overall performance improvement. By designing blade geometry with the proposed semi-inverse method whereby the blade pressure loading is specified instead of the conventional design approach of manually adjusting the blade angle to achieve blade design objectives, designers can discover blade geometry design space that has not been explored before.

Optimization of a Centrifugal Impeller Design Through CFD Analysis

NASA Technical Reports Server (NTRS)

Chen, W. C.; Eastland, A. H.; Chan, D. C.; Garcia, Roberto

1993-01-01

This paper discusses the procedure, approach and Rocketdyne CFD results for the optimization of the NASA consortium impeller design. Two different approaches have been investigated. The first one is to use a tandem blade arrangement, the main impeller blade is split into two separate rows with the second blade row offset circumferentially with respect to the first row. The second approach is to control the high losses related to secondary flows within the impeller passage. Many key parameters have been identified and each consortium team member involved will optimize a specific parameter using 3-D CFD analysis. Rocketdyne has provided a series of CFD grids for the consortium team members. SECA will complete the tandem blade study, SRA will study the effect of the splitter blade solidity change, NASA LeRC will evaluate the effect of circumferential position of the splitter blade, VPI will work on the hub to shroud blade loading distribution, NASA Ames will examine the impeller discharge leakage flow impacts and Rocketdyne will continue to work on the meridional contour and the blade leading to trailing edge work distribution. This paper will also present Rocketdyne results from the tandem blade study and from the blade loading distribution study. It is the ultimate goal of this consortium team to integrate the available CFD analysis to design an advanced technology impeller that is suitable for use in the NASA Space Transportation Main Engine (STME) fuel turbopump.

Magnetic particle testing of turbine blades mounted on the turbine rotor shaft

NASA Astrophysics Data System (ADS)

Imbert, Clement; Rampersad, Krishna

1992-07-01

An outline is presented of the general technique of magnetic particle inspection (MPI) of turbine blades mounted on the turbine rotor shaft with specific reference to the placement of the magnetizing coils. In particular, this study reports on the use of MPI in the examination of martensitic stainless steel turbine blades in power plants in Trinidad and Tobago in order to establish procedures for the detection of discontinuities. The techniques described are applicable to ferromagnetic turbine blades in general. The two practical techniques mentioned are the method of placing a preformed coil over a number of blades in one row and the method of wrapping the coil around the rotor shaft across an entire row of blades. Of the two methods, the former is preferred to the latter one, because there is greater uniformity of magnetic flux induced and lower current required to induce adequate flux density with the preformed coil. However, both methods provide satisfactory magnetic flux, and either can be used.

The method of complex characteristics for design of transonic blade sections

NASA Technical Reports Server (NTRS)

Bledsoe, M. R.

1986-01-01

A variety of computational methods were developed to obtain shockless or near shockless flow past two-dimensional airfoils. The approach used was the method of complex characteristics, which determines smooth solutions to the transonic flow equations based on an input speed distribution. General results from fluid mechanics are presented. An account of the method of complex characteristics is given including a description of the particular spaces and coordinates, conformal transformations, and numerical procedures that are used. The operation of the computer program COMPRES is presented along with examples of blade sections designed with the code. A user manual is included with a glossary to provide additional information which may be helpful. The computer program in Fortran, including numerous comment cards is listed.

Reference Specimen for Nondestructive Evaluation: Characterization of the Oxide Layer of a Cold Shot in Inconel 600

NASA Astrophysics Data System (ADS)

Saletes, I.; Filleter, T.; Goldbaum, D.; Chromik, R. R.; Sinclair, A. N.

2015-02-01

The presence of a cold shot in an aircraft turbine blade can lead to the catastrophic failure of the blade and ultimately to the failure of the power plant. Currently, no nondestructive evaluation (NDE) method exists to detect this kind of defect. This deficiency is primarily due to the fact that the only known cold shot defects in existence are those found in failed blades. Therefore, in order to develop effective NDE methods, reference specimens are needed which mimic the embedded oxide layer that is a primary distinguishing feature of a cold shot. Here, we present a procedure to synthetically reproduce the features of a real cold shot in Inconel 600 and the precise characterization of this oxide layer as a reference specimen suitable for NDE evaluation. As a first step to develop a suitable NDE technique, high-frequency ultrasound simulations are considered. A theoretical 1-D model is developed in order to quantify the multiple reflection-transmission trajectory of the acoustic wave in the reference specimen. This paper also presents an experimental determination of the density and the Young's modulus of the Inconel 600 oxide, which are required as inputs to calculate the acoustic impedance used in the theoretical model.

Designing a fixed-blade gang ripsaw arbor with a pencil

Treesearch

Charles J. Gatchell; Charles J. Gatchell

1996-01-01

This paper presents a step-by-step procedure for designing the "best" sequence of saw spacings for a fixed-blade gang ripsaw arbor. Using the information contained in a cutting bill and knowledge of the lumber width distributions to be processed, thousands of possible saw spacing sequences can be reduced to a few good ones.

The "Hands Together" Method of Nonsterile Scalpel Blade Mounting and Removal

ERIC Educational Resources Information Center

Cornwall, Jon

2014-01-01

Scalpels are utilized by many different user groups for such purposes as medical procedures and dissection. Injuries caused by scalpels are a potential risk for scalpel users, and include injuries that may occur while mounting and removing the scalpel blade. Between 10% and 20% of all scalpel injuries in education and healthcare settings are…

The Design of Pumpjets for Hydrodynamic Propulsion

NASA Technical Reports Server (NTRS)

Bruce, E. P.; Gearhart, W. S.; Ross, J. R.; Treaster, A. L.

1974-01-01

A procedure for use in the design of a wake adapted pumpjet mounted on the aft end of a body of revolution is presented. To this end, a pumpjet is designed for the Akron airship. The propulsor mass flow is selected to minimize kinetic energy losses through the duct and in the discharge jet. The shaft speed and disk size are selected to satisfy specified limits of cavitation performance and to provide acceptable blade loading. The streamtubes which pass through a propulsor mounted on a tapered afterbody follow essentially conical surfaces. A method is provided for defining these surfaces as a function of shroud geometry, rotor head distribution, and the energy distribution of the ingested mass flow. The three-dimensional effects to which the conical flow subjects the cylindrical blade design sections are described and a technique is presented which permits incorporation of these effects in the blade design procedure.

The Development of a Hollow Blade for Exhaust Gas Turbines

NASA Technical Reports Server (NTRS)

Kohlmann, H

1950-01-01

The subject of the development of German hollow turbine blades for use with internal cooling is discussed in detail. The development of a suitable blade profile from cascade theory is described. Also a discussion of the temperature distribution and stresses in a turbine blade is presented. Various methods of manufacturing hollow blades and the methods by which they are mounted in the turbine rotor are presented in detail.

Optimal design application on the advanced aeroelastic rotor blade

NASA Technical Reports Server (NTRS)

Wei, F. S.; Jones, R.

1985-01-01

The vibration and performance optimization procedure using regression analysis was successfully applied to an advanced aeroelastic blade design study. The major advantage of this regression technique is that multiple optimizations can be performed to evaluate the effects of various objective functions and constraint functions. The data bases obtained from the rotorcraft flight simulation program C81 and Myklestad mode shape program are analytically determined as a function of each design variable. This approach has been verified for various blade radial ballast weight locations and blade planforms. This method can also be utilized to ascertain the effect of a particular cost function which is composed of several objective functions with different weighting factors for various mission requirements without any additional effort.

Active control of wake/blade-row interaction noise through the use of blade surface actuators

NASA Technical Reports Server (NTRS)

Kousen, Kenneth A.; Verdon, Joseph M.

1993-01-01

A combined analytical/computational approach for controlling of the noise generated by wake/blade-row interaction through the use of anti-sound actuators on the blade surfaces is described. A representative two-dimensional section of a fan stage, composed of an upstream fan rotor and a downstream fan exit guide vane (FEGV), is examined. An existing model for the wakes generated by the rotor is analyzed to provide realistic magnitudes for the vortical excitations imposed at the inlet to the FEGV. The acoustic response of the FEGV is determined at multiples of the blade passing frequency (BPF) by using the linearized unsteady flow analysis, LINFLO. Acoustic field contours are presented at each multiple of BPF illustrating the generated acoustic response disturbances. Anti-sound is then provided by placing oscillating control surfaces, whose lengths and locations are specified arbitrarily, on the blades. An analysis is then conducted to determine the complex amplitudes required for the control surface motions to best reduce the noise. It is demonstrated that if the number of acoustic response modes to be controlled is equal to the number of available independent control surfaces, complete noise cancellation can be achieved. A weighted least squares minimization procedure for the control equations is given for cases in which the number of acoustic modes exceeds the number of available control surfaces. The effectiveness of the control is measured by the magnitude of a propagating acoustic response vector, which is related to the circumferentially averaged sound pressure level (SPL), and is minimized by a standard least-squares minimization procedure.

Active control of wake/blade-row interaction noise through the use of blade surface actuators

NASA Astrophysics Data System (ADS)

Kousen, Kenneth A.; Verdon, Joseph M.

1993-12-01

A combined analytical/computational approach for controlling of the noise generated by wake/blade-row interaction through the use of anti-sound actuators on the blade surfaces is described. A representative two-dimensional section of a fan stage, composed of an upstream fan rotor and a downstream fan exit guide vane (FEGV), is examined. An existing model for the wakes generated by the rotor is analyzed to provide realistic magnitudes for the vortical excitations imposed at the inlet to the FEGV. The acoustic response of the FEGV is determined at multiples of the blade passing frequency (BPF) by using the linearized unsteady flow analysis, LINFLO. Acoustic field contours are presented at each multiple of BPF illustrating the generated acoustic response disturbances. Anti-sound is then provided by placing oscillating control surfaces, whose lengths and locations are specified arbitrarily, on the blades. An analysis is then conducted to determine the complex amplitudes required for the control surface motions to best reduce the noise. It is demonstrated that if the number of acoustic response modes to be controlled is equal to the number of available independent control surfaces, complete noise cancellation can be achieved. A weighted least squares minimization procedure for the control equations is given for cases in which the number of acoustic modes exceeds the number of available control surfaces. The effectiveness of the control is measured by the magnitude of a propagating acoustic response vector, which is related to the circumferentially averaged sound pressure level (SPL), and is minimized by a standard least-squares minimization procedure.

Response of a Rotating Propeller to Aerodynamic Excitation

NASA Technical Reports Server (NTRS)

Arnoldi, Walter E.

1949-01-01

The flexural vibration of a rotating propeller blade with clamped shank is analyzed with the object of presenting, in matrix form, equations for the elastic bending moments in forced vibration resulting from aerodynamic forces applied at a fixed multiple of rotational speed. Matrix equations are also derived which define the critical speeds end mode shapes for any excitation order and the relation between critical speed and blade angle. Reference is given to standard works on the numerical solution of matrix equations of the forms derived. The use of a segmented blade as an approximation to a continuous blade provides a simple means for obtaining the matrix solution from the integral equation of equilibrium, so that, in the numerical application of the method presented, the several matrix arrays of the basic physical characteristics of the propeller blade are of simple form, end their simplicity is preserved until, with the solution in sight, numerical manipulations well-known in matrix algebra yield the desired critical speeds and mode shapes frame which the vibration at any operating condition may be synthesized. A close correspondence between the familiar Stodola method and the matrix method is pointed out, indicating that any features of novelty are characteristic not of the analytical procedure but only of the abbreviation, condensation, and efficient organization of the numerical procedure made possible by the use of classical matrix theory.

Experimental evidence of inter-blade cavitation vortex development in Francis turbines at deep part load condition

NASA Astrophysics Data System (ADS)

Yamamoto, K.; Müller, A.; Favrel, A.; Avellan, F.

2017-10-01

Francis turbines are subject to various types of cavitation flow depending on the operating condition. To enable a smooth integration of the renewable energy sources, hydraulic machines are now increasingly required to extend their operating range, especially down to extremely low discharge conditions called deep part load operation. The inter-blade cavitation vortex is a typical cavitation phenomenon observed at deep part load operation. However, its dynamic characteristics are insufficiently understood today. In an objective of revealing its characteristics, the present study introduces a novel visualization technique with instrumented guide vanes embedding the visualization devices, providing unprecedented views on the inter-blade cavitation vortex. The binary image processing technique enables the successful evaluation of the inter-blade cavitation vortex in the images. As a result, it is shown that the probability of the inter-blade cavitation development is significantly high close to the runner hub. Furthermore, the mean vortex line is calculated and the vortex region is estimated in the three-dimensional domain for the comparison with numerical simulation results. In addition, the on-board pressure measurements on a runner blade is conducted, and the influence of the inter-blade vortex on the pressure field is investigated. The analysis suggests that the presence of the inter-blade vortex can magnify the amplitude of pressure fluctuations especially on the blade suction side. Furthermore, the wall pressure difference between pressure and suction sides of the blade features partially low or negative values near the hub at the discharge region where the inter-blade vortex develops. This negative pressure difference on the blade wall suggests the development of a backflow region caused by the flow separation near the hub, which is closely related to the development of the inter-blade vortex. The development of the backflow region is confirmed by the numerical simulation, and the physical mechanisms of the inter-blade vortex development is, furthermore, discussed.

Development of an Active Twist Rotor for Wind: Tunnel Testing (NLPN97-310

NASA Technical Reports Server (NTRS)

Cesnik, Carlos E. S.; Shin, SangJoon; Hagood, Nesbitt W., IV

1998-01-01

The development of the Active Twist Rotor prototype blade for hub vibration and noise reduction studies is presented in this report. Details of the modeling, design, and manufacturing are explored. The rotor blade is integrally twisted by direct strain actuation. This is accomplished by distributing embedded piezoelectric fiber composites along the span of the blade. The development of the analysis framework for this type of active blade is presented. The requirements for the prototype blade, along with the final design results are also presented. A detail discussion on the manufacturing aspects of the prototype blade is described. Experimental structural characteristics of the prototype blade compare well with design goals, and preliminary bench actuation tests show lower performance than originally predicted. Electrical difficulties with the actuators are also discussed. The presented prototype blade is leading to a complete fully articulated four-blade active twist rotor system for future wind tunnel tests.

Blade-mounted trailing edge flap control for BVI noise reduction

NASA Technical Reports Server (NTRS)

Hassan, A. A.; Charles, B. D.; Tadghighi, H.; Sankar, L. N.

1992-01-01

Numerical procedures based on the 2-D and 3-D full potential equations and the 2-D Navier-Stokes equations were developed to study the effects of leading and trailing edge flap motions on the aerodynamics of parallel airfoil-vortex interactions and on the aerodynamics and acoustics of the more general self-generated rotor blade vortex interactions (BVI). For subcritical interactions, the 2-D results indicate that the trailing edge flap can be used to alleviate the impulsive loads experienced by the airfoil. For supercritical interactions, the results show the necessity of using a leading edge flap, rather than a trailing edge flap, to alleviate the interaction. Results for various time dependent flap motions and their effect on the predicted temporal sectional loads, differential pressures, and the free vortex trajectories are presented. For the OLS model rotor, contours of a BVI noise metric were used to quantify the effects of the trailing edge flap on the size and directivity of the high/low intensity noise region(s). Average reductions in the BVI noise levels on the order of 5 dB with moderate power penalties on the order of 18 pct. for a four bladed rotor and 58 pct. for a two bladed rotor were obtained.

Validation of the procedures. [integrated multidisciplinary optimization of rotorcraft

NASA Technical Reports Server (NTRS)

Mantay, Wayne R.

1989-01-01

Validation strategies are described for procedures aimed at improving the rotor blade design process through a multidisciplinary optimization approach. Validation of the basic rotor environment prediction tools and the overall rotor design are discussed.

Integrated aerodynamic/dynamic optimization of helicopter rotor blades

NASA Technical Reports Server (NTRS)

Chattopadhyay, Aditi; Walsh, Joanne L.; Riley, Michael F.

1989-01-01

An integrated aerodynamic/dynamic optimization procedure is used to minimize blade weight and 4 per rev vertical hub shear for a rotor blade in forward flight. The coupling of aerodynamics and dynamics is accomplished through the inclusion of airloads which vary with the design variables during the optimization process. Both single and multiple objective functions are used in the optimization formulation. The Global Criteria Approach is used to formulate the multiple objective optimization and results are compared with those obtained by using single objective function formulations. Constraints are imposed on natural frequencies, autorotational inertia, and centrifugal stress. The program CAMRAD is used for the blade aerodynamic and dynamic analyses, and the program CONMIN is used for the optimization. Since the spanwise and the azimuthal variations of loading are responsible for most rotor vibration and noise, the vertical airload distributions on the blade, before and after optimization, are compared. The total power required by the rotor to produce the same amount of thrust for a given area is also calculated before and after optimization. Results indicate that integrated optimization can significantly reduce the blade weight, the hub shear and the amplitude of the vertical airload distributions on the blade and the total power required by the rotor.

Development of a numerical procedure for mixed mode K-solutions and fatigue crack growth in FCC single crystal superalloys

NASA Astrophysics Data System (ADS)

Ranjan, Srikant

2005-11-01

Fatigue-induced failures in aircraft gas turbine and rocket engine turbopump blades and vanes are a pervasive problem. Turbine blades and vanes represent perhaps the most demanding structural applications due to the combination of high operating temperature, corrosive environment, high monotonic and cyclic stresses, long expected component lifetimes and the enormous consequence of structural failure. Single crystal nickel-base superalloy turbine blades are being utilized in rocket engine turbopumps and jet engines because of their superior creep, stress rupture, melt resistance, and thermomechanical fatigue capabilities over polycrystalline alloys. These materials have orthotropic properties making the position of the crystal lattice relative to the part geometry a significant factor in the overall analysis. Computation of stress intensity factors (SIFs) and the ability to model fatigue crack growth rate at single crystal cracks subject to mixed-mode loading conditions are important parts of developing a mechanistically based life prediction for these complex alloys. A general numerical procedure has been developed to calculate SIFs for a crack in a general anisotropic linear elastic material subject to mixed-mode loading conditions, using three-dimensional finite element analysis (FEA). The procedure does not require an a priori assumption of plane stress or plane strain conditions. The SIFs KI, KII, and KIII are shown to be a complex function of the coupled 3D crack tip displacement field. A comprehensive study of variation of SIFs as a function of crystallographic orientation, crack length, and mode-mixity ratios is presented, based on the 3D elastic orthotropic finite element modeling of tensile and Brazilian Disc (BD) specimens in specific crystal orientations. Variation of SIF through the thickness of the specimens is also analyzed. The resolved shear stress intensity coefficient or effective SIF, Krss, can be computed as a function of crack tip SIFs and the resolved shear stress on primary slip planes. The maximum value of Krss and DeltaKrss was found to determine the crack growth direction and the fatigue crack growth rate respectively. The fatigue crack driving force parameter, DeltaK rss, forms an important multiaxial fatigue damage parameter that can be used to predict life in superalloy components.

Aerodynamic Design of Axial-flow Compressors. Volume 2

NASA Technical Reports Server (NTRS)

1956-01-01

Available experimental two-dimensional-cascade data for conventional compressor blade sections are correlated. The two-dimensional cascade and some of the principal aerodynamic factors involved in its operation are first briefly described. Then the data are analyzed by examining the variation of cascade performance at a reference incidence angle in the region of minimum loss. Variations of reference incidence angle, total-pressure loss, and deviation angle with cascade geometry, inlet Mach number, and Reynolds number are investigated. From the analysis and the correlations of the available data, rules and relations are evolved for the prediction of the magnitude of the reference total-pressure loss and the reference deviation and incidence angles for conventional blade profiles. These relations are developed in simplified forms readily applicable to compressor design procedures.

A calculation procedure for viscous flow in turbomachines, volume 2

NASA Technical Reports Server (NTRS)

Khalil, J.; Tabakoff, W.

1980-01-01

Turbulent flow within turbomachines having arbitrary blade geometries is examined. Effects of turbulence are modeled using two equations, one expressing the development of the turbulence kinetic energy and the other its dissipation rate. To account for complicated blade geometries, the flow equations are formulated in terms of a nonorthogonal boundary fitted coordinate system. The analysis is applied to a radial inflow turbine. The solution obtained indicates the severity of the complex interaction mechanism that occurs between the different flow regimes (i.e., boundary layers, recirculating eddies, separation zones, etc.). Comparison with nonviscous flow solutions tend to justify strongly the inadequacy of using the latter with standard boundary layer techniques to obtain viscous flow details within turbomachine rotors. Capabilities and limitations of the present method of analysis are discussed.

Design and Evaluation of Glass/epoxy Composite Blade and Composite Tower Applied to Wind Turbine

NASA Astrophysics Data System (ADS)

Park, Hyunbum

2018-02-01

In the study, the analysis and manufacturing of small class wind turbine blade was performed. In the structural design, firstly the loading conditions are defined through the load case analysis. The proposed structural configuration of blade has a sandwich type composite structure with the E-glass/Epoxy face sheets and the Urethane foam core for lightness, structural stability, low manufacturing cost and easy manufacturing process. And also, this work proposes a design procedure and results of tower for the small scale wind turbine systems. Structural analysis of blade including load cases, stress, deformation, buckling, vibration and fatigue life was performed using the finite element method, the load spectrum analysis and the Miner rule. Moreover, investigation on structural safety of tower was verified through structural analysis by FEM. The manufacturing of blade and tower was performed based on structural design. In order to investigate the designed structure, the structural tests were conducted and its results were compared with the calculated results. It is confirmed that the final proposed blade and tower meet the design requirements.

Minimum weight design of rectangular and tapered helicopter rotor blades with frequency constraints

NASA Technical Reports Server (NTRS)

Chattopadhyay, Aditi; Walsh, Joanne L.

1988-01-01

The minimum weight design of a helicopter rotor blade subject to constraints on coupled flap-lag natural frequencies has been studied. A constraint has also been imposed on the minimum value of the autorotational inertia of the blade in order to ensure that it has sufficient inertia to autorotate in the case of engine failure. The program CAMRAD is used for the blade modal analysis and CONMIN is used for the optimization. In addition, a linear approximation analysis involving Taylor series expansion has been used to reduce the analysis effort. The procedure contains a sensitivity analysis which consists of analytical derivatives of the objective function and the autorotational inertia constraint and central finite difference derivatives of the frequency constraints. Optimum designs have been obtained for both rectangular and tapered blades. Design variables include taper ratio, segment weights, and box beam dimensions. It is shown that even when starting with an acceptable baseline design, a significant amount of weight reduction is possible while satisfying all the constraints for both rectangular and tapered blades.

Minimum weight design of rectangular and tapered helicopter rotor blades with frequency constraints

NASA Technical Reports Server (NTRS)

Chattopadhyay, Aditi; Walsh, Joanne L.

1988-01-01

The minimum weight design of a helicopter rotor blade subject to constraints on coupled flap-lag natural frequencies has been studied. A constraint has also been imposed on the minimum value of the autorotational inertia of the blade in order to ensure that it has sufficient inertia to aurorotate in the case of engine failure. The program CAMRAD is used for the blade modal analysis and CONMIN is used for the optimization. In addition, a linear approximation analysis involving Taylor series expansion has been used to reduce the analysis effort. The procedure contains a sensitivity analysis which consists of analytical derivatives of the objective function and the autorotational inertia constraint and central finite difference derivatives of the frequency constraints. Optimum designs have been obtained for both rectangular and tapered blades. Design variables include taper ratio, segment weights, and box beam dimensions. It is shown that even when starting with an acceptable baseline design, a significant amount of weight reduction is possible while satisfying all the constraints for both rectangular and tapered blades.

Evaluation of a doubly-swept blade tip for rotorcraft noise reduction

NASA Technical Reports Server (NTRS)

Wake, Brian E.; Egolf, T. Alan

1992-01-01

A computational study was performed for a doubly-swept rotor blade tip to determine its benefit for high-speed impulsive (HSI) and blade-vortex interaction (BVI) noise. This design consists of aft and forward sweep. For the HSI-noise computations, unsteady Euler calculations were performed for several variations to a rotor blade geometry. A doubly-swept planform was predicted to increase the delocalizing Mach number to 0.94 (representative of a 200+ kt helicopter). For the BVI-noise problem, it had been hypothesized that the doubly-swept blade tip, by producing a leading-edge vortex, would reduce the tip-vortex effect on BVI noise. A procedure was used in which the tip vortex velocity profile computed by a Navier-Stokes solver was used to compute the inflow associated with BVI. This inflow was used by a Euler solver to compute the unsteady pressures for an acoustic analysis. The results of this study were inconclusive due to the difficulty in accurately predicting the viscous tip vortex downstream of the blade. Also, for the condition studied, no leading-edge vortex formed at the tip.

Miniature high temperature plug-type heat flux gauges

NASA Technical Reports Server (NTRS)

Liebert, Curt H.

1992-01-01

The objective is to describe continuing efforts to develop methods for measuring surface heat flux, gauge active surface temperature, and heat transfer coefficient quantities. The methodology involves inventing a procedure for fabricating improved plug-type heat flux gauges and also for formulating inverse heat conduction models and calculation procedures. These models and procedures are required for making indirect measurements of these quantities from direct temperature measurements at gauge interior locations. Measurements of these quantities were made in a turbine blade thermal cycling tester (TBT) located at MSFC. The TBT partially simulates the turbopump turbine environment in the Space Shuttle Main Engine. After the TBT test, experiments were performed in an arc lamp to analyze gauge quality.

Hydraulic development of high specific-speed pump-turbines by means of an inverse design method, numerical flow-simulation (CFD) and model testing

NASA Astrophysics Data System (ADS)

Kerschberger, P.; Gehrer, A.

2010-08-01

In recent years an increased interest in pump-turbines has been recognized in the market. The rapid availability of pumped storage schemes and the benefits to the power system by peak lopping, providing reserve and rapid response for frequency control are becoming of growing advantage. In that context it is requested to develop pump-turbines that reliably stand dynamic operation modes, fast changes of the discharge rate by adjusting the variable diffuser vanes as well as fast changes from pump to turbine operation. Within the present study various flow patterns linked to the operation of a pump-turbine system are discussed. In that context pump and turbine mode are presented separately and different load cases at both operation modes are shown. In order to achieve modern, competitive pump-turbine designs it is further explained which design challenges should be considered during the geometry definition of a pump-turbine impeller. Within the present study a runner-blade profile for a low head pump-turbine has been developed. For the initial hydraulic runner-blade design, an inverse design method has been applied. Within this design procedure, a first blade geometry is generated by imposing the pressure loading-distribution and by means of an inverse 3D potential-flow-solution. The hydraulic behavior of both, pump-mode and turbine-mode is then evaluated by solving the full 3D Navier-Stokes equations in combination with a robust turbulence model. Based on this initial design the blade profile has been further optimized and redesigned considering various hydraulic pump-turbine requirements. Finally, the progress in hydraulic design is demonstrated by model test results which show a significant improvement in hydraulic performance compared to an existing reference design.

Biomechanical comparison of blade plate and intramedullary nail fixation for tibiocalcaneal arthrodesis.

PubMed

Lee, Arthur T; Sundberg, Eric B; Lindsey, Derek P; Harris, Alex H S; Chou, Loretta B

2010-02-01

Tibiocalcaneal arthrodesis is an uncommon salvage procedure used for complex problems of the ankle and hindfoot. A biomechanical evaluation of the fixation constructs of this procedure has not been studied previously. The purpose of this study was to compare intramedullary nail to blade plate fixation in a deformity model in fatigue endurance testing and load to failure. Nine matched pairs of fresh frozen cadaveric legs underwent talectomy followed by fixation with a blade plate and 6.5-mm fully threaded cancellous screw or an ankle arthrodesis intramedullary nail. The specimens were loaded to 270 N at a rate of 3 Hz for a total of 250,000 cycles, followed by loading to failure. Intramedullary nail fixation demonstrated greater mean stiffness throughout the fatigue endurance testing, from cycles 10 through 250,000 (blade plate versus intramedullary nail; cycle 10, 93 +/- 34 N/mm versus 117 +/- 40 N/mm (t = 2.33, p = 0.04); cycle 100, 89 +/- 34 N/mm versus 118 +/- 42 N/mm (t = 3.16, p = 0.01); cycle 1000, 86 +/- 32 N/mm versus 120 +/- 45 N/mm (t = 3.52, p = 0.01); cycle 10,000, 83 +/- 36 N/mm versus 128 +/- 50 N/mm (t = 3.80, p = 0.01); cycle 100,000, 82 +/- 34 N/mm versus 126 +/- 52 N/mm (t = 3.70, p = 0.01); cycle 250,000, 80 +/- 31 N/mm versus 125 +/- 49 N/mm (t = 4.2, p = 0.003). There was no statistically significant difference between the intramedullary nail and blade plate fixation in cycle one or in load to failure; cycle 10, blade plate 70 +/- 38 N/mm and intramedullary nail 67 +/- 20 N/mm (t = 0.60, p = 0.56); load to failure, blade plate 808 +/- 193 N, IMN 1074 +/- 290 N) (p = 0.15). Intramedullary nail fixation was biomechanically superior to blade plate and screw fixation in a tibiocalcaneal arthrodesis construct. The ankle arthrodesis intramedullary nail provides greater stiffness for fixation in tibiocalcaneal arthrodesis, which may improve healing.

A method to estimate weight and dimensions of large and small gas turbine engines

NASA Technical Reports Server (NTRS)

Onat, E.; Klees, G. W.

1979-01-01

A computerized method was developed to estimate weight and envelope dimensions of large and small gas turbine engines within + or - 5% to 10%. The method is based on correlations of component weight and design features of 29 data base engines. Rotating components were estimated by a preliminary design procedure which is sensitive to blade geometry, operating conditions, material properties, shaft speed, hub tip ratio, etc. The development and justification of the method selected, and the various methods of analysis are discussed.

Study on measurement of leading and trailing edges of blades based on optical scanning system

NASA Astrophysics Data System (ADS)

Chao, Bi; Liu, Hongguang; Bao, Longxiang; Li, Di

2017-10-01

In the field of aeronautics, the geometry and dimensional accuracy of the blade edges has a large influence on the aerodynamic performance of aero engine. Therefore, a non-contact optical scanning system is established to realize the measurement of leading and trailing edges of blades in a rapid, precise and efficient manner in the paper. Based on the mechanical framework of a traditional CMM, the system is equipped with a specified sensing device as the scanning probe, which is made up by two new-style laser scanning sensors installed at a certain angle to each other by a holder. In the measuring procedure, the geometric dimensions of the measured blade edges on every contour plane are determined by the contour information on five transversals at the leading or trailing edges, which can be used to determine the machining allowance of the blades. In order to verify the effectiveness and practicality of the system set up, a precision forging blade after grinded is adopted as the measured object and its leading and trailing edges are measured by the system respectively. In the experiment, the thickness of blade edges on three contour planes is measured by the optical scanning system several times. As the experiment results show, the repeatability accuracy of the system can meet its design requirements and the inspecting demands of the blade edges. As a result, the optical scanning system could serve as a component of the intelligent manufacturing system of blades to improve the machining quality of the blade edges.

Investigation of advanced counterrotation blade configuration concepts for high speed turboprop systems. Task 5: Unsteady counterrotation ducted propfan analysis

NASA Technical Reports Server (NTRS)

Hall, Edward J.; Delaney, Robert A.

1993-01-01

The primary objective of this study was the development of a time-marching three-dimensional Euler/Navier-Stokes aerodynamic analysis to predict steady and unsteady compressible transonic flows about ducted and unducted propfan propulsion systems employing multiple blade rows. The computer codes resulting from this study are referred to as ADPAC-AOAR\\CR (Advanced Ducted Propfan Analysis Codes-Angle of Attack Coupled Row). This document is the final report describing the theoretical basis and analytical results from the ADPAC-AOACR codes developed under task 5 of NASA Contract NAS3-25270, Unsteady Counterrotating Ducted Propfan Analysis. The ADPAC-AOACR Program is based on a flexible multiple blocked grid discretization scheme permitting coupled 2-D/3-D mesh block solutions with application to a wide variety of geometries. For convenience, several standard mesh block structures are described for turbomachinery applications. Aerodynamic calculations are based on a four-stage Runge-Kutta time-marching finite volume solution technique with added numerical dissipation. Steady flow predictions are accelerated by a multigrid procedure. Numerical calculations are compared with experimental data for several test cases to demonstrate the utility of this approach for predicting the aerodynamics of modern turbomachinery configurations employing multiple blade rows.

Investigation of advanced counterrotation blade configuration concepts for high speed turboprop systems. Task 5: Unsteady counterrotation ducted propfan analysis. Computer program user's manual

NASA Technical Reports Server (NTRS)

Hall, Edward J.; Delaney, Robert A.; Adamczyk, John J.; Miller, Christopher J.; Arnone, Andrea; Swanson, Charles

1993-01-01

The primary objective of this study was the development of a time-marching three-dimensional Euler/Navier-Stokes aerodynamic analysis to predict steady and unsteady compressible transonic flows about ducted and unducted propfan propulsion systems employing multiple blade rows. The computer codes resulting from this study are referred to as ADPAC-AOACR (Advanced Ducted Propfan Analysis Codes-Angle of Attack Coupled Row). This report is intended to serve as a computer program user's manual for the ADPAC-AOACR codes developed under Task 5 of NASA Contract NAS3-25270, Unsteady Counterrotating Ducted Propfan Analysis. The ADPAC-AOACR program is based on a flexible multiple blocked grid discretization scheme permitting coupled 2-D/3-D mesh block solutions with application to a wide variety of geometries. For convenience, several standard mesh block structures are described for turbomachinery applications. Aerodynamic calculations are based on a four-stage Runge-Kutta time-marching finite volume solution technique with added numerical dissipation. Steady flow predictions are accelerated by a multigrid procedure. Numerical calculations are compared with experimental data for several test cases to demonstrate the utility of this approach for predicting the aerodynamics of modern turbomachinery configurations employing multiple blade rows.

Single versus double blade technique for skin incision and deep dissection in surgery for closed fracture: a prospective randomised control study.

PubMed

Trikha, V; Saini, P; Mathur, P; Agarwal, A; Kumar, S V; Choudhary, B

2016-04-01

To compare blade cultures in surgery for closed fracture using a single or double blade technique to determine whether the current practice of double blade technique is justified. 155 men and 29 women aged 20 to 60 (mean, 35) years who underwent surgery for closed fracture with healthy skin at the incision site were included. Patients were block randomised to the single (n=92) or double (n=92) blade technique. Blades were sent for bacteriological analysis. Outcome measures were early surgical site infection (SSI) within 30 days and cultures from the blades. The 2 groups were comparable in baseline characteristics. In the single blade group, 6 surgical blades and 2 control blades showed positive cultures; 4 patients developed SSI, but only one had a positive culture from the surgical blade (with different organism isolated from the wound culture). In the double blade group, 6 skin blades, 7 deep blades, and 0 control blade showed positive culture; only 2 patients had the same bacteria grown from both skin and deep blade. Five patients developed SSI, but only one patient had a positive culture from the deep blade (with different organism isolated from the wound culture). The difference in incidence of culture-positive blade or SSI between the 2 groups was not significant. The relative risk of SSI in the single blade group was 0.8. Positive blade culture was not associated with SSI in the single or double blade group. The practice of changing blade following skin incision has no effect on reducing early SSI in surgery for closed fracture in healthy patients with healthy skin.

Damage Identification of Wind Turbine Blades Using Piezoelectric Transducers

DOE PAGES

Choi, Seong-Won; Farinholt, Kevin M.; Taylor, Stuart G.; ...

2014-01-01

This paper presents the experimental results of active-sensing structural health monitoring (SHM) techniques, which utilize piezoelectric transducers as sensors and actuators, for determining the structural integrity of wind turbine blades. Specifically, Lamb wave propagations and frequency response functions at high frequency ranges are used to estimate the condition of wind turbine blades. For experiments, a 1 m section of a CX-100 blade is used. The goal of this study is to assess and compare the performance of each method in identifying incipient damage with a consideration given to field deployability. Overall, these methods yielded a sufficient damage detection capability to warrantmore » further investigation. This paper also summarizes the SHM results of a full-scale fatigue test of a 9 m CX-100 blade using piezoelectric active sensors. This paper outlines considerations needed to design such SHM systems, experimental procedures and results, and additional issues that can be used as guidelines for future investigations.« less

Developments in blade shape design for a Darrieus vertical axis wind turbine

NASA Astrophysics Data System (ADS)

Ashwill, T. D.; Leonard, T. M.

1986-09-01

A new computer program package has been developed that determines the troposkein shape for a Darrieus Vertical Axis Wind Turbine Blade with any geometrical configuration or rotation rate. This package allows users to interact and develop a buildable blade whose shape closely approximates the troposkein. Use of this package can significantly reduce flatwise mean bending stresses in the blade and increase fatigue life.

Application of response surface techniques to helicopter rotor blade optimization procedure

NASA Technical Reports Server (NTRS)

Henderson, Joseph Lynn; Walsh, Joanne L.; Young, Katherine C.

1995-01-01

In multidisciplinary optimization problems, response surface techniques can be used to replace the complex analyses that define the objective function and/or constraints with simple functions, typically polynomials. In this work a response surface is applied to the design optimization of a helicopter rotor blade. In previous work, this problem has been formulated with a multilevel approach. Here, the response surface takes advantage of this decomposition and is used to replace the lower level, a structural optimization of the blade. Problems that were encountered and important considerations in applying the response surface are discussed. Preliminary results are also presented that illustrate the benefits of using the response surface.

Shot peening for Ti-6Al-4V alloy compressor blades

NASA Technical Reports Server (NTRS)

Carek, Gerald A.

1987-01-01

A text program was conducted to determine the effects of certain shot-peening parameters on the fatigue life of the Ti-6Al-4V alloys as well as the effect of a demarcation line on a test specimen. This demarcation line, caused by an abrupt change from untreated surface to shot-peened surface, was thought to have caused the failure of several blades in a multistage compressor at the NASA Lewis Research Center. The demarcation line had no detrimental effect upon bending fatigue specimens tested at room temperature. Procedures for shot peening Ti-6Al-4V compressor blades are recommended for future applications.

Design and Test of a Transonic Axial Splittered Rotor

DTIC Science & Technology

2015-06-15

AXIAL SPLITTERED ROTOR A new design procedure was developed that uses commercial-off-the-shelf software (MATLAB, SolidWorks, and ANSYS-CFX) for the...geometric rendering and analysis of a transonic axial compressor rotor with splitter blades. Predictive numerical simulations were conducted and...Compressor, Splittered Rotor REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 10. SPONSOR/MONITOR’S ACRONYM(S) ARO 8. PERFORMING

Development of a linearized unsteady aerodynamic analysis for cascade gust response predictions

NASA Technical Reports Server (NTRS)

Verdon, Joseph M.; Hall, Kenneth C.

1990-01-01

A method for predicting the unsteady aerodynamic response of a cascade of airfoils to entropic, vortical, and acoustic gust excitations is being developed. Here, the unsteady flow is regarded as a small perturbation of a nonuniform isentropic and irrotational steady background flow. A splitting technique is used to decompose the linearized unsteady velocity into rotational and irrotational parts leading to equations for the complex amplitudes of the linearized unsteady entropy, rotational velocity, and velocity potential that are coupled only sequentially. The entropic and rotational velocity fluctuations are described by transport equations for which closed-form solutions in terms of the mean-flow drift and stream functions can be determined. The potential fluctuation is described by an inhomogeneous convected wave equation in which the source term depends on the rotational velocity field, and is determined using finite-difference procedures. The analytical and numerical techniques used to determine the linearized unsteady flow are outlined. Results are presented to indicate the status of the solution procedure and to demonstrate the impact of blade geometry and mean blade loading on the aerodynamic response of cascades to vortical gust excitations. The analysis described herein leads to very efficient predictions of cascade unsteady aerodynamic response phenomena making it useful for turbomachinery aeroelastic and aeroacoustic design applications.

Design of an active helicopter control experiment at the Princeton Rotorcraft Dynamics Laboratory

NASA Technical Reports Server (NTRS)

Marraffa, Andrew M.; Mckillip, R. M., Jr.

1989-01-01

In an effort to develop an active control technique for reducing helicopter vibrations stemming from the main rotor system, a helicopter model was designed and tested at the Princeton Rotorcraft Dynamics Laboratory (PRDL). A description of this facility, including its latest data acquisition upgrade, are given. The design procedures for the test model and its Froude scaled rotor system are also discussed. The approach for performing active control is based on the idea that rotor states can be identified by instrumenting the rotor blades. Using this knowledge, Individual Blade Control (IBC) or Higher Harmonic Control (HHC) pitch input commands may be used to impact on rotor dynamics in such a way as to reduce rotor vibrations. Discussed here is an instrumentation configuration utilizing miniature accelerometers to measure and estimate first and second out-of-plane bending mode positions and velocities. To verify this technique, the model was tested, and resulting data were used to estimate rotor states as well as flap and bending coefficients, procedures for which are discussed. Overall results show that a cost- and time-effective method for building a useful test model for future active control experiments was developed. With some fine-tuning or slight adjustments in sensor configuration, prospects for obtaining good state estimates look promising.

Structural tailoring of engine blades (STAEBL) user's manual

NASA Technical Reports Server (NTRS)

Brown, K. W.

1985-01-01

This User's Manual contains instructions and demonstration case to prepare input data, run, and modify the Structural Tailoring of Engine Blades (STAEBL) computer code. STAEBL was developed to perform engine fan and compressor blade numerical optimizations. This blade optimization seeks a minimum weight or cost design that satisfies realistic blade design constraints, by tuning one to twenty design variables. The STAEBL constraint analyses include blade stresses, vibratory response, flutter, and foreign object damage. Blade design variables include airfoil thickness at several locations, blade chord, and construction variables: hole size for hollow blades, and composite material layup for composite blades.

Fan Blade Shake Test Results for the 40- by 80-/80- by 120-Foot Wind Tunnel

NASA Technical Reports Server (NTRS)

Warmbrodt, W.; Graham, T.

1983-01-01

This report documents the shake tests performed on the first set of hydulignum fan blades for the 40- by 80-/80- by 120-Foot Wind Tunnel. The purpose of the shake test program is described. The test equipment and test procedures are reviewed. Results from each shake test are presented and the overall findings of the shake test program are discussed.

Interaction of impeller and guide vane in a series-designed axial-flow pump

NASA Astrophysics Data System (ADS)

Kim, S.; Choi, Y. S.; Lee, K. Y.; Kim, J. H.

2012-11-01

In this paper, the interaction of the impeller and guide vane in a series-designed axial-flow pump was examined through the implementation of a commercial CFD code. The impeller series design refers to the general design procedure of the base impeller shape which must satisfy the various flow rate and head requirements by changing the impeller setting angle and number of blades of the base impeller. An arc type meridional shape was used to keep the meridional shape of the hub and shroud with various impeller setting angles. The blade angle and the thickness distribution of the impeller were designed as an NACA airfoil type. In the design of the guide vane, it was necessary to consider the outlet flow condition of the impeller with the given setting angle. The meridional shape of the guide vane were designed taking into consideration the setting angle of the impeller, and the blade angle distribution of the guide vane was determined with a traditional design method using vane plane development. In order to achieve the optimum impeller design and guide vane, three-dimensional computational fluid dynamics and the DOE method were applied. The interaction between the impeller and guide vane with different combination set of impeller setting angles and number of impeller blades was addressed by analyzing the flow field of the computational results.

The MOD-1 steel blade

NASA Technical Reports Server (NTRS)

Vanbronkhorst, J.

1979-01-01

The design, development, fabrication, testing, and transport of two 100 foot metal blades for the MOD-1 WTS are summarized. Because the metal blade design was started late in the MOD-1 system development, many of the design requirements (allocations) were restrictive for the metal blade concept, particularly the maximum weight requirement. The design solutions required to achieve the weight goal resulted in a labor intensive (expensive) fabrication, particularly for a quantity of only two blades manufactured using minimal tooling.

On the design and structural analysis of jet engine fan blade structures

NASA Astrophysics Data System (ADS)

Amoo, Leye M.

2013-07-01

Progress in the design and structural analysis of commercial jet engine fan blades is reviewed and presented. This article is motivated by the key role fan blades play in the performance of advanced gas turbine jet engines. The fundamentals of the associated physics are emphasized. Recent developments and advancements have led to an increase and improvement in fan blade structural durability, stability and reliability. This article is intended as a high level review of the fan blade environment and current state of structural design to aid further research in developing new and innovative fan blade technologies.

Frequency domain system identification of helicopter rotor dynamics incorporating models with time periodic coefficients

NASA Astrophysics Data System (ADS)

Hwang, Sunghwan

1997-08-01

One of the most prominent features of helicopter rotor dynamics in forward flight is the periodic coefficients in the equations of motion introduced by the rotor rotation. The frequency response characteristics of such a linear time periodic system exhibits sideband behavior, which is not the case for linear time invariant systems. Therefore, a frequency domain identification methodology for linear systems with time periodic coefficients was developed, because the linear time invariant theory cannot account for sideband behavior. The modulated complex Fourier series was introduced to eliminate the smearing effect of Fourier series expansions of exponentially modulated periodic signals. A system identification theory was then developed using modulated complex Fourier series expansion. Correlation and spectral density functions were derived using the modulated complex Fourier series expansion for linear time periodic systems. Expressions of the identified harmonic transfer function were then formulated using the spectral density functions both with and without additive noise processes at input and/or output. A procedure was developed to identify parameters of a model to match the frequency response characteristics between measured and estimated harmonic transfer functions by minimizing an objective function defined in terms of the trace of the squared frequency response error matrix. Feasibility was demonstrated by the identification of the harmonic transfer function and parameters for helicopter rigid blade flapping dynamics in forward flight. This technique is envisioned to satisfy the needs of system identification in the rotating frame, especially in the context of individual blade control. The technique was applied to the coupled flap-lag-inflow dynamics of a rigid blade excited by an active pitch link. The linear time periodic technique results were compared with the linear time invariant technique results. Also, the effect of noise processes and initial parameter guess on the identification procedure were investigated. To study the effect of elastic modes, a rigid blade with a trailing edge flap excited by a smart actuator was selected and system parameters were successfully identified, but with some expense of computational storage and time. Conclusively, the linear time periodic technique substantially improved the identified parameter accuracy compared to the linear time invariant technique. Also, the linear time periodic technique was robust to noises and initial guess of parameters. However, an elastic mode of higher frequency relative to the system pumping frequency tends to increase the computer storage requirement and computing time.

Sweep-twist adaptive rotor blade : final project report.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ashwill, Thomas D.

2010-02-01

Knight & Carver was contracted by Sandia National Laboratories to develop a Sweep Twist Adaptive Rotor (STAR) blade that reduced operating loads, thereby allowing a larger, more productive rotor. The blade design used outer blade sweep to create twist coupling without angled fiber. Knight & Carver successfully designed, fabricated, tested and evaluated STAR prototype blades. Through laboratory and field tests, Knight & Carver showed the STAR blade met the engineering design criteria and economic goals for the program. A STAR prototype was successfully tested in Tehachapi during 2008 and a large data set was collected to support engineering and commercialmore » development of the technology. This report documents the methodology used to develop the STAR blade design and reviews the approach used for laboratory and field testing. The effort demonstrated that STAR technology can provide significantly greater energy capture without higher operating loads on the turbine.« less

Experimental impact testing and analysis of composite fan cases

NASA Astrophysics Data System (ADS)

Vander Klok, Andrew Joe

For aircraft engine certification, one of the requirements is to demonstrate the ability of the engine to withstand a fan blade-out (FBO) event. A FBO event may be caused by fatigue failure of the fan blade itself or by impact damage of foreign objects such as bird strike. An un-contained blade can damage flight critical engine components or even the fuselage. The design of a containment structure is related to numerous parameters such as the blade tip speed; blade material, size and shape; hub/tip diameter; fan case material, configuration, rigidity, etc. To investigate all parameters by spin experiments with a full size rotor assembly can be prohibitively expensive. Gas gun experiments can generate useful data for the design of engine containment cases at much lower costs. To replicate the damage modes similar to that on a fan case in FBO testing, the gas gun experiment has to be carefully designed. To investigate the experimental procedure and data acquisition techniques for FBO test, a low cost, small spin rig was first constructed. FBO tests were carried out with the small rig. The observed blade-to-fan case interactions were similar to those reported using larger spin rigs. The small rig has the potential in a variety of applications from investigating FBO events, verifying concept designs of rotors, to developing spin testing techniques. This rig was used in the developments of the notched blade releasing mechanism, a wire trigger method for synchronized data acquisition, high speed video imaging and etc. A relationship between the notch depth and the release speed was developed and verified. Next, an original custom designed spin testing facility was constructed. Driven by a 40HP, 40,000rpm air turbine, the spin rig is housed in a vacuum chamber of phi72inx40in (1829mmx1016mm). The heavily armored chamber is furnished with 9 viewports. This facility enables unprecedented investigations of FBO events. In parallel, a 15.4ft (4.7m) long phi4.1inch (105mm) diameter single stage gas gun was developed. A thermodynamic based relationship between the required gas pressure and targeted velocity was proposed. The predicted velocity was within +/-7%. Quantitative measurements of force and displacement were attempted. The transmitted impact force was measured with load cells. The out-of-plane deformation was measured with a projection grating profilometry method. The composite panels and fan cases used in this work were made of S2-glass plain weave fabrics with API SC-15 toughened epoxy resin using the vacuum assisted resin transfer molding (VARTM) method. Using the gas gun, the impact behavior of the composite was investigated at velocities ranging from 984ft/s to 1502ft/s (300m/s to 458m/s) following a draft ASTM testing standard. To compare the ballistic protection capability of different materials, a new parameter EBL, the projectile kinetic energy at the target ballistic limit normalized by the contact area of the projectile, was proposed. S2-glass/epoxy composite is ranked very high in EBL per areal weight. Finally, a testing method for replicating spin pit testing with a gas gun test was developed. Major differences between the two tests are the initial conditions of the blade upon contact with the target. In spin testing, the released blade has two velocity components, rotational and translational whereas in gas gun testing, the projectile has only the translational velocity. To account for the influence of the rotational velocity, three projectile designs were experimentally investigated. The results show that to generate similar damage modes in gas gun testing, it is critical to ensure the deformation of the projectile before testing is similar to that of a released blade. With the pre-bent blade, the gas gun experiment was able to replicate the damage modes of the fan case in FBO test on flat composite panels.

Developing a passive load reduction blade for the DTU 10 MW reference turbine

NASA Astrophysics Data System (ADS)

de Vaal, J. B.; Nygaard, T. A.; Stenbro, R.

2016-09-01

This paper presents the development of a passive load reduction blade for the DTU 10 MW reference wind turbine, using the aero-hydro-servo-elastic analysis tool 3DFloat. Passive load reduction is achieved by introducing sweep to the path of the blade elastic axis, so that out-of-plane bending deflections result in load alleviating torsional deformations of the blade. Swept blades are designed to yield similar annual energy production as a rotor with a reference straight blade. This is achieved by modifying the aerodynamic twist distribution for swept blades based on non-linear blade deflection under steady state loads. The passive load reduction capability of a blade design is evaluated by running a selection of fatigue- and extreme load cases with the analysis tool 3DFloat and determining equivalent fatigue loads, fatigue damage and extreme loads at the blade root and tower base. The influence of sweep on the flutter speed of a blade design is also investigated. A large number of blade designs are evaluated by varying the parameters defining the sweep path of a blade's elastic axis. Results show that a moderate amount of sweep can effectively reduce equivalent fatigue damage and extreme loads, without significantly reducing the flutter speed, or compromising annual energy production.

Development of a locally mass flux conservative computer code for calculating 3-D viscous flow in turbomachines

NASA Technical Reports Server (NTRS)

Walitt, L.

1982-01-01

The VANS successive approximation numerical method was extended to the computation of three dimensional, viscous, transonic flows in turbomachines. A cross-sectional computer code, which conserves mass flux at each point of the cross-sectional surface of computation was developed. In the VANS numerical method, the cross-sectional computation follows a blade-to-blade calculation. Numerical calculations were made for an axial annular turbine cascade and a transonic, centrifugal impeller with splitter vanes. The subsonic turbine cascade computation was generated in blade-to-blade surface to evaluate the accuracy of the blade-to-blade mode of marching. Calculated blade pressures at the hub, mid, and tip radii of the cascade agreed with corresponding measurements. The transonic impeller computation was conducted to test the newly developed locally mass flux conservative cross-sectional computer code. Both blade-to-blade and cross sectional modes of calculation were implemented for this problem. A triplet point shock structure was computed in the inducer region of the impeller. In addition, time-averaged shroud static pressures generally agreed with measured shroud pressures. It is concluded that the blade-to-blade computation produces a useful engineering flow field in regions of subsonic relative flow; and cross-sectional computation, with a locally mass flux conservative continuity equation, is required to compute the shock waves in regions of supersonic relative flow.

Structural Testing of the Blade Reliability Collaborative Effect of Defect Wind Turbine Blades

DOE Office of Scientific and Technical Information (OSTI.GOV)

Desmond, M.; Hughes, S.; Paquette, J.

Two 8.3-meter (m) wind turbine blades intentionally constructed with manufacturing flaws were tested to failure at the National Wind Technology Center (NWTC) at the National Renewable Energy Laboratory (NREL) south of Boulder, Colorado. Two blades were tested; one blade was manufactured with a fiberglass spar cap and the second blade was manufactured with a carbon fiber spar cap. Test loading primarily consisted of flap fatigue loading of the blades, with one quasi-static ultimate load case applied to the carbon fiber spar cap blade. Results of the test program were intended to provide the full-scale test data needed for validation ofmore » model and coupon test results of the effect of defects in wind turbine blade composite materials. Testing was part of the Blade Reliability Collaborative (BRC) led by Sandia National Laboratories (SNL). The BRC seeks to develop a deeper understanding of the causes of unexpected blade failures (Paquette 2012), and to develop methods to enable blades to survive to their expected operational lifetime. Recent work in the BRC includes examining and characterizing flaws and defects known to exist in wind turbine blades from manufacturing processes (Riddle et al. 2011). Recent results from reliability databases show that wind turbine rotor blades continue to be a leading contributor to turbine downtime (Paquette 2012).« less

A procedure for preparing undecalcified and unembedded bone sections for light microscopy.

PubMed

Mancini, M; Spoliti, M; Botti, F; Ragazzoni, E; Cocchia, D

1997-07-01

We have developed a procedure for light microscopic investigation of undecalcified and unembedded bone sections. Biopsy samples of human metatarsus and femur and rat femur were fixed in aldehydes and sectioned with a cutting machine equipped with a diamond saw blade. Free sections 100-150 microns thick, stained with toluidine blue and von Kossa, did not show artifacts following the cutting, and the spatial relations of mineralized and nonmineralized components remained intact. Compact and trabecular bone, bone marrow and all cell types appeared well preserved and easily recognizable. Our procedure provides a simple and rapid method for preparing bone sections which undergo no chemical treatment other than fixation. This method is a useful alternative to standard histological protocols for studying bone specimens.

Fast-Running Aeroelastic Code Based on Unsteady Linearized Aerodynamic Solver Developed

NASA Technical Reports Server (NTRS)

Reddy, T. S. R.; Bakhle, Milind A.; Keith, T., Jr.

2003-01-01

The NASA Glenn Research Center has been developing aeroelastic analyses for turbomachines for use by NASA and industry. An aeroelastic analysis consists of a structural dynamic model, an unsteady aerodynamic model, and a procedure to couple the two models. The structural models are well developed. Hence, most of the development for the aeroelastic analysis of turbomachines has involved adapting and using unsteady aerodynamic models. Two methods are used in developing unsteady aerodynamic analysis procedures for the flutter and forced response of turbomachines: (1) the time domain method and (2) the frequency domain method. Codes based on time domain methods require considerable computational time and, hence, cannot be used during the design process. Frequency domain methods eliminate the time dependence by assuming harmonic motion and, hence, require less computational time. Early frequency domain analyses methods neglected the important physics of steady loading on the analyses for simplicity. A fast-running unsteady aerodynamic code, LINFLUX, which includes steady loading and is based on the frequency domain method, has been modified for flutter and response calculations. LINFLUX, solves unsteady linearized Euler equations for calculating the unsteady aerodynamic forces on the blades, starting from a steady nonlinear aerodynamic solution. First, we obtained a steady aerodynamic solution for a given flow condition using the nonlinear unsteady aerodynamic code TURBO. A blade vibration analysis was done to determine the frequencies and mode shapes of the vibrating blades, and an interface code was used to convert the steady aerodynamic solution to a form required by LINFLUX. A preprocessor was used to interpolate the mode shapes from the structural dynamic mesh onto the computational dynamics mesh. Then, we used LINFLUX to calculate the unsteady aerodynamic forces for a given mode, frequency, and phase angle. A postprocessor read these unsteady pressures and calculated the generalized aerodynamic forces, eigenvalues, and response amplitudes. The eigenvalues determine the flutter frequency and damping. As a test case, the flutter of a helical fan was calculated with LINFLUX and compared with calculations from TURBO-AE, a nonlinear time domain code, and from ASTROP2, a code based on linear unsteady aerodynamics.

Design optimization of axial flow hydraulic turbine runner: Part II - multi-objective constrained optimization method

NASA Astrophysics Data System (ADS)

Peng, Guoyi; Cao, Shuliang; Ishizuka, Masaru; Hayama, Shinji

2002-06-01

This paper is concerned with the design optimization of axial flow hydraulic turbine runner blade geometry. In order to obtain a better design plan with good performance, a new comprehensive performance optimization procedure has been presented by combining a multi-variable multi-objective constrained optimization model with a Q3D inverse computation and a performance prediction procedure. With careful analysis of the inverse design of axial hydraulic turbine runner, the total hydraulic loss and the cavitation coefficient are taken as optimization objectives and a comprehensive objective function is defined using the weight factors. Parameters of a newly proposed blade bound circulation distribution function and parameters describing positions of blade leading and training edges in the meridional flow passage are taken as optimization variables.The optimization procedure has been applied to the design optimization of a Kaplan runner with specific speed of 440 kW. Numerical results show that the performance of designed runner is successfully improved through optimization computation. The optimization model is found to be validated and it has the feature of good convergence. With the multi-objective optimization model, it is possible to control the performance of designed runner by adjusting the value of weight factors defining the comprehensive objective function. Copyright

The Shock and Vibration Bulletin. Part 1. Welcome, Keynote Address, Invited Papers, Pyrotechnic Shock, and Shock Testing and Analysis

DTIC Science & Technology

1983-05-01

DESIGN PROCEDURE M. S. IIAndal, University of Vermont, Burlington, VT Machinery Dynamics ANALYTICAL AND EXPERIMENTAL INVESTIGATION OF ROTATING BLADE... methodology to accurately predict rotor vibratory loads and has recently been initiated for detail design and bench test- coupled rotor/airframe vibrations... design methodology , a trating on the basic disciplines of aerodynamics and struc. coupled rotor/airframe vibration analysis has been developed. tural

Current Problems in Turbomachinery Fluid Dynamics.

DTIC Science & Technology

1982-05-21

Research Center. It is thought to result from the termination of the 3-D bow shock as the relAtive blade Mach decreases ,.zom tip to hub. This low...project emphasized development of at least a plausible inverse scheme for mixed supersonic, subsonic flow with the possibility of shock waves appearing...Calculation Procedure for Shock -Free or Strong Passage Shock Turbomachinery Cascades," ASME paper 82-GT-220. The next phase of this project was expected to

Design of a blade stiffened composite panel by a genetic algorithm

NASA Technical Reports Server (NTRS)

Nagendra, S.; Haftka, R. T.; Gurdal, Z.

1993-01-01

Genetic algorithms (GAs) readily handle discrete problems, and can be made to generate many optima, as is presently illustrated for the case of design for minimum-weight stiffened panels with buckling constraints. The GA discrete design procedure proved superior to extant alternatives for both stiffened panels with cutouts and without cutouts. High computational costs are, however, associated with this discrete design approach at the current level of its development.

Single-stage experimental evaluation of tandem-airfoil rotor and stator blading for compressors. Part 7: Data and performance for stage E

NASA Technical Reports Server (NTRS)

Cheatham, J. G.

1974-01-01

An axial flow compressor stage, having tandem airfoil blading, was designed for zero rotor prewhirl, constant rotor work across the span, and axial discharge flow. The stage was designed to produce a pressure ratio of 1.265 at a rotor tip velocity of 757 ft/sec. The rotor has an inlet hub/tip ratio of 0.8. The design procedure accounted for the rotor inlet boundary layer and included the effects of axial velocity ratio and secondary flow on blade row performance. The objectives of this experimental program were (1) to obtain performance with uniform and distorted inlet flow for comparison with the performance of a stage consisting of single-airfoil blading designed for the same vector diagrams and (2) to evaluate the effectiveness of accounting for the inlet boundary layer, axial velocity ratio, and secondary flows in the stage design.

Interactive multi-mode blade impact analysis

NASA Technical Reports Server (NTRS)

Alexander, A.; Cornell, R. W.

1978-01-01

The theoretical methodology used in developing an analysis for the response of turbine engine fan blades subjected to soft-body (bird) impacts is reported, and the computer program developed using this methodology as its basis is described. This computer program is an outgrowth of two programs that were previously developed for the purpose of studying problems of a similar nature (a 3-mode beam impact analysis and a multi-mode beam impact analysis). The present program utilizes an improved missile model that is interactively coupled with blade motion which is more consistent with actual observations. It takes into account local deformation at the impact area, blade camber effects, and the spreading of the impacted missile mass on the blade surface. In addition, it accommodates plate-type mode shapes. The analysis capability in this computer program represents a significant improvement in the development of the methodology for evaluating potential fan blade materials and designs with regard to foreign object impact resistance.

Preliminary Solar Sail Design and Fabrication Assessment: Spinning Sail Blade, Square Sail Sheet

NASA Technical Reports Server (NTRS)

Daniels, J. B.; Dowdle, D. M.; Hahn, D. W.; Hildreth, E. N.; Lagerquist, D. R.; Mahaonoul, E. J.; Munson, J. B.; Origer, T. F.

1977-01-01

Blade design aspects most affecting producibility and means of measurement and control of length, scallop, fullness and straightness requirements and tolerances were extensively considered. Alternate designs of the panel seams and edge reinforcing members are believed to offer advantages of seam integrity, producibility, reliability, cost and weight. Approaches to and requirements for highly specialized metalizing methods, processes and equipment were studied and identified. Alternate methods of sail blade fabrication and related special machinery, tooling, fixtures and trade offs were examined. A preferred and recommended approach is also described. Quality control plans, inspection procedures, flow charts and special test equipment associated with the preferred manufacturing method were analyzed and are discussed.

System Developed for Real-Time Blade-Flutter Monitoring in the Wind Tunnel

NASA Technical Reports Server (NTRS)

Kurkov, Anatole P.; Dhadwal, Harbans S.; Radzikowski, mark; Strukov, Dmitri

2005-01-01

A real-time system has been developed to monitor flutter vibrations in turbomachinery. The system is designed for continuous processing of blade tip timing data at a rate of 10 MB/sec. A USB 2.0 interface provides uninterrupted real-time processing of the data, and the blade-tip arrival times are measured with a 50-MHz oscillator and a 24-bit pipelined architecture counter. The input stage includes a glitch catcher, which reduces the probability of detecting a ghost blade to negligible levels. A graphical user interface provides online interrogation of any blade tip from any light probe sensor. Alternatively, data from all blades and all sensors can be superimposed into a single composite scatter plot displaying the vibration amplitude of each blade.

Growian rotor blades: Production development, construction and test

NASA Technical Reports Server (NTRS)

Thiele, H. M.

1984-01-01

Development and construction of three 50 m rotor blades for a 3 MW wind turbine are described. A hybrid concept was chosen, i.e., a load carrying inflexible steel spar and a glass fiber reinforced plastic skin. A test blade was constructed and static loading tests, dynamic vibration tests and fatigue tests on critical welds as well as at the connection between spar and blade skin were performed. All test results show good accordance with calculated values, and were taken into consideration during the construction of two rotor blades.

Unified continuum damage model for matrix cracking in composite rotor blades

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pollayi, Hemaraju; Harursampath, Dineshkumar

This paper deals with modeling of the first damage mode, matrix micro-cracking, in helicopter rotor/wind turbine blades and how this effects the overall cross-sectional stiffness. The helicopter/wind turbine rotor system operates in a highly dynamic and unsteady environment leading to severe vibratory loads present in the system. Repeated exposure to this loading condition can induce damage in the composite rotor blades. These rotor/turbine blades are generally made of fiber-reinforced laminated composites and exhibit various competing modes of damage such as matrix micro-cracking, delamination, and fiber breakage. There is a need to study the behavior of the composite rotor system undermore » various key damage modes in composite materials for developing Structural Health Monitoring (SHM) system. Each blade is modeled as a beam based on geometrically non-linear 3-D elasticity theory. Each blade thus splits into 2-D analyzes of cross-sections and non-linear 1-D analyzes along the beam reference curves. Two different tools are used here for complete 3-D analysis: VABS for 2-D cross-sectional analysis and GEBT for 1-D beam analysis. The physically-based failure models for matrix in compression and tension loading are used in the present work. Matrix cracking is detected using two failure criterion: Matrix Failure in Compression and Matrix Failure in Tension which are based on the recovered field. A strain variable is set which drives the damage variable for matrix cracking and this damage variable is used to estimate the reduced cross-sectional stiffness. The matrix micro-cracking is performed in two different approaches: (i) Element-wise, and (ii) Node-wise. The procedure presented in this paper is implemented in VABS as matrix micro-cracking modeling module. Three examples are presented to investigate the matrix failure model which illustrate the effect of matrix cracking on cross-sectional stiffness by varying the applied cyclic load.« less

Rotor dynamic simulation and system identification methods for application to vacuum whirl data

NASA Technical Reports Server (NTRS)

Berman, A.; Giansante, N.; Flannelly, W. G.

1980-01-01

Methods of using rotor vacuum whirl data to improve the ability to model helicopter rotors were developed. The work consisted of the formulation of the equations of motion of elastic blades on a hub using a Galerkin method; the development of a general computer program for simulation of these equations; the study and implementation of a procedure for determining physical parameters based on measured data; and the application of a method for computing the normal modes and natural frequencies based on test data.

A Prospective Randomized Study Comparing Disposable with Reusable Blades for a Morcellator Device.

PubMed

Becker, Benedikt; Orywal, Ann Katrin; Hausmann, Teresa; Gross, Andreas J; Netsch, Christopher

2017-03-01

Transurethral enucleation of the prostate for the management of benign prostatic obstruction (BPO) involves two steps: the enucleation and morcellation procedure. The aim of our study was to assess the efficacy of a morcellator device using disposable and reusable blades with different settings of morcellation speed. A prospective randomized study was initiated for patients with symptomatic BPO undergoing Thulium laser enucleation of the prostate. Mechanical tissue morcellation was performed using the Piranha™ morcellator (R. Wolf, Knittlingen, Germany) with disposable or reusable blades at 850 (n = 24) or 1500 revolutions per minute (rpm) (n = 24). Patient characteristics, intraoperative complications, and the morcellation rate (g/min) were recorded. Data are expressed as median and interquartile range (IQR). Forty-eight patients were randomized using disposable (n = 24) or reusable blades (n = 24). For reusable blades, the morcellation rate did not increase when changing the morcellation speed from 850 to 1500 rpm (5 vs 4.53 g/min, p = 0.843). The morcellation rate increased significantly when changing the morcellation speed from 850 to 1500 rpm using single-use blades (4.77 vs 10 g/min, p ≤ 0.014). The morcellation rate was not different at 850 rpm between reusable and single-use blades (5 vs 4.77 g/min, p = 0.671). Conversely, the morcellation rate was significantly different at 1500 rpm between reusable and single-use blades (4.53 vs 10 g/min, p ≤ 0.017). The total morcellation rate (at 850 and 1500 rpm) was significantly increased using single-use blades compared to reusable blades (7.67 vs 4.8 g/min, p ≤ 0.026). Interestingly, enucleated weight (g) and the morcellation rate (g/min) correlated inversely using single-use blades at 1500 rpm (r = -0.742, p ≤ 0.004). Only one superficial bladder injury occurred at 1500 rpm, which needed no further interventions. The Piranha morcellator facilitates efficient tissue removal with single-use and reusable blades. Disposable morcellator blades increase tissue removal significantly at 1500 rpm.

Real-time estimation of helicopter rotor blade kinematics through measurement of rotation induced acceleration

NASA Astrophysics Data System (ADS)

Allred, C. Jeff; Churchill, David; Buckner, Gregory D.

2017-07-01

This paper presents a novel approach to monitoring rotor blade flap, lead-lag and pitch using an embedded gyroscope and symmetrically mounted MEMS accelerometers. The central hypothesis is that differential accelerometer measurements are proportional only to blade motion; fuselage acceleration and blade bending are inherently compensated for. The inverse kinematic relationships (from blade position to acceleration and angular rate) are derived and simulated to validate this hypothesis. An algorithm to solve the forward kinematic relationships (from sensor measurement to blade position) is developed using these simulation results. This algorithm is experimentally validated using a prototype device. The experimental results justify continued development of this kinematic estimation approach.

Installation Effects on Heat Transfer Measurements for a Turbine Vane

DTIC Science & Technology

2003-03-01

turbine vanes and blades in order to acquire high accuracy, high frequency response data. Typically the installation procedure has involved either mounting...length scale such as blade chord) again matches the engine value. Also before the start of the run a choke valve downstream of the turbine is set to...of Engineering for Gas Turbines and Power (January 1984), Volume 106. p 229 - 240. Gibbings, J.C. “On boundary Layer Transition Wires.” Aeronautical

Automated inspection of turbine blades: Challenges and opportunities

NASA Technical Reports Server (NTRS)

Mehta, Manish; Marron, Joseph C.; Sampson, Robert E.; Peace, George M.

1994-01-01

Current inspection methods for complex shapes and contours exemplified by aircraft engine turbine blades are expensive, time-consuming and labor intensive. The logistics support of new manufacturing paradigms such as integrated product-process development (IPPD) for current and future engine technology development necessitates high speed, automated inspection of forged and cast jet engine blades, combined with a capability of retaining and retrieving metrology data for process improvements upstream (designer-level) and downstream (end-user facilities) at commercial and military installations. The paper presents the opportunities emerging from a feasibility study conducted using 3-D holographic laser radar in blade inspection. Requisite developments in computing technologies for systems integration of blade inspection in production are also discussed.

Optical tomography for flow visualization of the density field around a revolving helicopter rotor blade

NASA Technical Reports Server (NTRS)

Snyder, R.; Hesselink, L.

1984-01-01

In this paper, a tomographic procedure for reconstructing the density field around a helicopter rotor blade tip from remote optical line-of-sight measurements is discussed. Numerical model studies have been carried out to investigate the influence of the number of available views, limited width viewing, and ray bending on the reconstruction. Performance is measured in terms of the mean-square error. It is found that very good reconstructions can be obtained using only a small number of views even when the width of view is smaller than the spatial extent of the object. An iterative procedure is used to correct for ray bending due to refraction associated with the sharp density gradients (shocks).

Development of an active twist rotor blade with distributed actuation and orthotropic material

NASA Astrophysics Data System (ADS)

Wierach, Peter; Riemenschneider, Johannes; Keye, Stefan

2005-05-01

Individual blade control (IBC) as well as higher harmonic control (HHC) for helicopter rotors promises to be a method to increase flight performance and to reduce vibration and noise. For those controls, an additional twist actuation of the rotor blade is needed. The developed concept comprises the implementation of distributed piezoelectric actuation into the rotor blade skin. In order to maximize the twist within given constraints, as torsional rigidity and given actuator design, the concept takes advantage of an orthotropic rotor blade skin. That way, a combination of shear actuation with orthotropic coupling generates more twist than each one of these effects alone. Previous approaches with distributed actuation used actuators operating in +/-45° direction with quasi-isotropic composites. A FE-Model of the blade was developed and validated using a simplified demonstrator. The objective of this study was to identify the effects of various geometric and material parameters to optimize the active twist performance of the blades. The whole development was embedded in an iterative process followed by an objective assessment. For this purpose a detailed structural model on the basis of the BO105 model rotor blade was developed, to predict the performance with respect to rotor dynamics, stability, aerodynamics and acoustics. Rotor dynamic simulations provided an initial overview of the active twist rotor performance. In comparison to the BO105 baseline rotor a noise reduction of 3 dB was predicted for an active twist of 0.8° at the blade tip. Additionally, a power reduction of 2.3% at 87m/s based on a 2.5 to BO105 was computed. A demonstrator blade with a rotor radius of 2m has been designed and manufactured. This blade will be tested to prove, that the calculated maximum twist can also be achieved under centrifugal loads.

Rotor blade system with reduced blade-vortex interaction noise

NASA Technical Reports Server (NTRS)

Leishman, John G. (Inventor); Han, Yong Oun (Inventor)

2005-01-01

A rotor blade system with reduced blade-vortex interaction noise includes a plurality of tube members embedded in proximity to a tip of each rotor blade. The inlets of the tube members are arrayed at the leading edge of the blade slightly above the chord plane, while the outlets are arrayed at the blade tip face. Such a design rapidly diffuses the vorticity contained within the concentrated tip vortex because of enhanced flow mixing in the inner core, which prevents the development of a laminar core region.

Impact force identification for composite helicopter blades using minimal sensing

NASA Astrophysics Data System (ADS)

Budde, Carson N.

In this research a method for online impact identification using minimal sensors is developed for rotor hubs with composite blades. Modal impact data and the corresponding responses are recorded at several locations to develop a frequency response function model for each composite blade on the rotor hub. The frequency response model for each blade is used to develop an impact identification algorithm which can be used to identify the location and magnitude of impacts. Impacts are applied in two experimental setups, including a four-blade spin test rig and a cantilevered full-sized composite blade. The impacts are estimated to have been applied at the correct location 92.3% of the time for static fiberglass blades, 97.4% of the time for static carbon fiber blades and 99.2% of the time for a full sized-static blade. The estimated location is assessed further and determined to have been estimated in the correct chord position 96.1% of the time for static fiberglass, 100% of the time for carbon fiber blades and 99.2% of the time for the full-sized blades. Projectile impacts are also applied statically and during rotation to the carbon fiber blades on the spin test rig at 57 and 83 RPM. The applied impacts can be located to the correct position 63.9%, 41.7% and 33.3% for the 0, 57 and 83 RPM speeds, respectively, while the correct chord location is estimated 100% of the time. The impact identification algorithm also estimates the force of an impact with an average percent difference of 4.64, 2.61 and 1.00 for static fiberglass, full sized, and carbon fiber blades, respectively. Using a load cell and work equations, the force of impact for a projectile fired from a dynamic firing setup is estimated at about 400 N. The average force measured for applied projectile impacts to the carbon fiber blades, rotating at 0, 57 and 83 RPM, is 368.8, 373.7 and 432.4 N, respectively.

Mach number scaling of helicopter rotor blade/vortex interaction noise

NASA Technical Reports Server (NTRS)

Leighton, Kenneth P.; Harris, Wesley L.

1985-01-01

A parametric study of model helicopter rotor blade slap due to blade vortex interaction (BVI) was conducted in a 5 by 7.5-foot anechoic wind tunnel using model helicopter rotors with two, three, and four blades. The results were compared with a previously developed Mach number scaling theory. Three- and four-bladed rotor configurations were found to show very good agreement with the Mach number to the sixth power law for all conditions tested. A reduction of conditions for which BVI blade slap is detected was observed for three-bladed rotors when compared to the two-bladed baseline. The advance ratio boundaries of the four-bladed rotor exhibited an angular dependence not present for the two-bladed configuration. The upper limits for the advance ratio boundaries of the four-bladed rotors increased with increasing rotational speed.

Design and analysis of axial aspirated compressor stages

NASA Astrophysics Data System (ADS)

Merchant, Ali A.

The pressure ratio of axial compressor stages can be significantly increased by controlling the development of blade and endwall boundary layers in regions of adverse pressure gradient by means of boundary layer suction. This concept is validated and demonstrated through the design and analysis of two unique aspirated compressor stages: a low-speed stage with a design pressure ratio of 1.6 at a tip speed of 750 ft/s, and a high-speed stage with a design pressure ratio of 3.5 at a tip speed of 1500 ft/s. The aspirated compressor stages were designed using a new procedure which is a synthesis of low speed and high speed blade design techniques combined with a flexible inverse design method which enabled precise independent control over the shape of the blade suction and pressure surfaces. Integration of the boundary layer suction calculation into the overall design process is an essential ingredient of the new procedure. The blade design system consists of two axisymmetric through-flow codes coupled with a quasi three-dimensional viscous cascade plane code with inverse design capability. Validation of the completed designs were carried out with three-dimensional Euler and Navier-Stokes calculations. A single spanwise slot on the blade suction surface is used to bleed the boundary layer. The suction mass flow requirement for the low-speed and high-speed stages are 1% and 4% of the inlet mass flow, respectively. Additional suction between 1-2% is also required on the compressor endwalls near shock impingement locations. The rotor is modeled with a tip shroud to eliminate tip clearance effects and to discharge the suction flow radially from the flowpath. Three-dimensional viscous evaluation of the designs showed good agreement with the quasi three-dimensional design intent, except in the endwall regions. The suction requirements predicted by the quasi three-dimensional calculation were confirmed by the three-dimensional viscous calculations. The three-dimensional viscous analysis predicted a peak pressure ratio of 1.59 at an isentropic efficiency of 89% for the low-speed stage, and a peak pressure ratio of 3.68 at an isentropic efficiency of 94% for the high-speed rotor. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.)

Methodology of Blade Unsteady Pressure Measurement in the NASA Transonic Flutter Cascade

NASA Technical Reports Server (NTRS)

Lepicovsky, J.; McFarland, E. R.; Capece, V. R.; Jett, T. A.; Senyitko, R. G.

2002-01-01

In this report the methodology adopted to measure unsteady pressures on blade surfaces in the NASA Transonic Flutter Cascade under conditions of simulated blade flutter is described. The previous work done in this cascade reported that the oscillating cascade produced waves, which for some interblade phase angles reflected off the wind tunnel walls back into the cascade, interfered with the cascade unsteady aerodynamics, and contaminated the acquired data. To alleviate the problems with data contamination due to the back wall interference, a method of influence coefficients was selected for the future unsteady work in this cascade. In this approach only one blade in the cascade is oscillated at a time. The majority of the report is concerned with the experimental technique used and the experimental data generated in the facility. The report presents a list of all test conditions for the small amplitude of blade oscillations, and shows examples of some of the results achieved. The report does not discuss data analysis procedures like ensemble averaging, frequency analysis, and unsteady blade loading diagrams reconstructed using the influence coefficient method. Finally, the report presents the lessons learned from this phase of the experimental effort, and suggests the improvements and directions of the experimental work for tests to be carried out for large oscillation amplitudes.

A new blade element method for calculating the performance of high and intermediate solidity axial flow fans

NASA Technical Reports Server (NTRS)

Borst, H. V.

1978-01-01

A method is presented to design and predict the performance of axial flow rotors operating in a duct. The same method is suitable for the design of ducted fans and open propellers. The unified method is based on the blade element approach and the vortex theory for determining the three dimensional effects, so that two dimensional airfoil data can be used for determining the resultant force on each blade element. Resolution of this force in the thrust and torque planes and integration allows the total performance of the rotor, fan or propeller to be predicted. Three different methods of analysis, one based on a momentum flow theory; another on the vortex theory of propellers; and a third based on the theory of ducted fans, agree and reduce cascade airfoil data to single line as a function of the loading and induced angle of attack at values of constant inflow angle. The theory applies for any solidity from .01 to over 1 and any blade section camber. The effects of the duct and blade number can be determined so that the procedure applies over the entire range from two blade open propellers, to ducted helicopter tail rotors, to axial flow compressors with or without guide vanes, and to wind tunnel drive fans.

Eutectic Composite Turbine Blade Development

DTIC Science & Technology

1976-11-01

turbine blades for aircraft engines . An MC carbide fiber reinforced eutectic alloy, NiTaC-13...composites in turbine blades for aircraft engines . An MC carbide fiber reinforced eutectic alloy, NiTaC-13 and the low pressure turbine blade of the...identified that appeared to have potential for application to aircraft engine turbine blade hardware. The potential benefits offered by these materials

High-Frequency Axial Fatigue Test Procedures for Spectrum Loading

DTIC Science & Technology

2016-07-20

histories can be performed at frequencies much higher than standard servo-hydraulic test frames by using a test frame that is optimized to run at higher...by using a test frame that is optimized to run at higher frequencies. AIR 4.3 has conducted a research program to develop a test capability for...Applied Research (BAR) program (219BAR-10-008) was initiated in 2010. The program investigated the influence of a generic rotorcraft main rotor blade root

Automated eddy current inspection of Space Shuttle APU turbine wheel blades

NASA Technical Reports Server (NTRS)

Fisher, Jay L.; Rowland, Stephen N.; Stolte, Jeffrey S.; Salkowski, Charles

1991-01-01

An automated inspection system based on eddy current testing (ET) techniques has been developed to inspect turbine wheel blades on the APU used in NASA's Space Transportation system. The APU is a hydrazine-powered gas turbine with a 15-cm diameter Rene 41 turbine wheel, which has 123 first-stage blades and 123 second-stage blades. The flaw detection capability of the ET system is verified through comparison with fluorescent penetrant test results. Results of the comparison indicate that ET is capable of inspecting surfaces with very restrictive geometries. The ET capability requires development of probes with extremely small coils to allow inspection within 0.4 mm of the blade root and the leading and trailing edges of the blade and within a height restriction of less than 1 mm. The color 2D presentation of the ET data provided crack-growth pattern and length information similar to those found with visual techniques. It also provided visual clues to minimize geometry effects such as generated from blade edges, a neighoring blade, and changes in the blade thickness.

High fidelity simulation of non-synchronous vibration for aircraft engine fan/compressor

NASA Astrophysics Data System (ADS)

Im, Hong-Sik

The objectives of this research are to develop a high fidelity simulation methodology for turbomachinery aeromechanical problems and to investigate the mechanism of non-synchronous vibration (NSV) of an aircraft engine axial compressor. A fully conservative rotor/stator sliding technique is developed to accurately capture the unsteadiness and interaction between adjacent blade rows. Phase lag boundary conditions (BC) based on the time shift (direct store) method and the Fourier series phase lag BC are implemented to take into account the effect of phase difference for a sector of annulus simulation. To resolve the nonlinear interaction between flow and vibrating blade structure, a fully coupled fluid-structure interaction (FSI) procedure that solves the structural modal equations and time accurate Navier-Stokes equations simultaneously is adopted. An advanced mesh deformation method that generates the blade tip block mesh moving with the blade displacement is developed to ensure the mesh quality. An efficient and low diffusion E-CUSP (LDE) scheme as a Riemann solver designed to minimize numerical dissipation is used with an improved hybrid RANS/LES turbulence strategy, delayed detached eddy simulation (DDES). High order accuracy (3rd and 5th order) weighted essentially non-oscillatory (WENO) schemes for inviscid flux and a conservative 2nd and 4th order viscous flux differencing are employed. Extensive validations are conducted to demonstrate high accuracy and robustness of the high fidelity FSI simulation methodology. The validated cases include: (1) DDES of NACA 0012 airfoil at high angle of attack with massive separation. The DDES accurately predicts the drag whereas the URANS model significantly over predicts the drag. (2) The AGARD Wing 445.6 flutter boundary is accurately predicted including the point at supersonic incoming flow. (3) NASA Rotor 67 validation for steady state speed line and radial profiles at peak efficiency point and near stall point. The calculated results agree excellently with the experiment. (4) NASA Stage 35 speed line and radial profiles to validate the steady state mixing plane BC for multistage computation. Excellent agreement is obtained between the computation and experiment. (5) NASA Rotor 67 full annulus and single passage FSI simulation at near peak condition to validate phase lag BC. The time shifted phase lag BC accurately predicts blade vibration responses that agrees better with the full annulus FSI simulation. The DDES methodology is used to investigate the stall inception of NASA Rotor 67. The stall process begins with spike inception and develops to full stall. The whole process is simulated with full annulus of the rotor. The fully coupled FSI is then used to simulate the stall flutter of NASA Rotor 67. The multistage simulations of a GE aircraft engine high pressure compressor (HPC) reveal for the first time that the travelling tornado vortex formed on the rotor blade tip region is the root cause for the NSV of the compressor. The rotor blades under NSV have large torsional vibration due to the tornado vortex propagation in the opposite to the rotor rotation. The tornado vortex frequency passing the suction surface of each blade in the tip region agrees with the NSV frequency. The predicted NSV frequency based on URANS model with rigid blades agrees very well with the experimental measurement with only 3.3% under-predicted. The NSV prediction using FSI with vibrating blades also obtain the same frequency as the rigid blades. This is because that the NSV is primarily caused by the flow vortex instability and the no resonance occurs. The blade structures respond passively and the small amplitudes of the blade vibration do not have significant effect on the flow. The predicted frequency using DDES with rigid blades is more deviated from the experiment and is 14.7% lower. The reason is that the DDES tends to predict the rotor stall earlier than the URANS and the NSV can be achieved only at higher mass flow rate, which generates a lower frequency. The possible reason for the DDES to predict the rotor stall early may be because DDES is more sensitive to wave reflection and a non-reflective boundary condition may be necessary. Overall, the high fidelity FSI methodology developed in this thesis for aircraft engine fan/compressor aeromechanics simulation is demonstrated to be very successful and has advanced the forefront of the state of the art. Future work to continue to improve the accuracy and efficiency is discussed at the end of the thesis.

Design and Development of Turbodrill Blade Used in Crystallized Section

PubMed Central

Yu, Wang; Jianyi, Yao; Zhijun, Li

2014-01-01

Turbodrill is a type of hydraulic axial turbomachinery which has a multistage blade consisting of stators and rotors. In this paper, a turbodrill blade that can be applied in crystallized section under high temperature and pressure conditions is developed. On the basis of Euler equations, the law of energy transfer is analyzed and the output characteristics of turbodrill blade are proposed. Moreover, considering the properties of the layer and the bole-hole conditions, the radical size, the geometrical dimension, and the blade profile are optimized. A computational model of a single-stage blade is built on the ANSYS CFD into which the three-dimensional model of turbodrill is input. In light of the distribution law of the pressure and flow field, the functions of the turbodrill blade are improved and optimized. The turbodrill blade optimization model was verified based on laboratory experiments. The results show that the design meets the deep hard rock mineral exploration application and provides good references for further study. PMID:25276857

Turbomachinery Design Quality Checks to Avoid Friction Induced Structural Failure

NASA Technical Reports Server (NTRS)

Moore, Jerry H.

1999-01-01

A unique configuration of the P&W SSME Alternate Fuel Turbopump turbine disk/blade assembly, combined with a severe thermal environment, resulted in several structural anomalies that were driven by frictional contact forces. Understanding the mechanics of these problems provides new quality checks for future turbo machinery designs. During development testing in 1997 of the SSME alternate fuel turbopump at Stennis Space Center, several potentially serious problems surfaced with the turbine disk/blade assembly that had not been experienced in extensive earlier testing. Changes to the operational thermal environment were noted based on analytical prediction of modifications that affected performance and on stationary thermal measurements adjacent to the rotor assembly. A detailed structural investigation was required to reveal the mechanism of distress induced by the change. The turbine disk experienced cracking in several locations due to increased thermal gradient induced stress during start and shutdown transients. This was easily predictable using standard analysis procedures and expected once the thermal environment was characterized. What was not expected was the curling of a piston ring used for blade axial retention in the disk, indentation of the axial face of the blade attachment by a spacer separating the first and second stage blades, and most significantly, galling and cracking of the blade root attachment that could have resulted in blade release. Past experience, in gas turbine environments, set a precedent of never relying on friction for help and to evaluate it only in specific instances where it was obvious that it would degrade capability. In each of the three cases above, friction proved to be a determining factor that pushed the components into an unsatisfactory mode of operation. The higher than expected temperatures and rapid thermal transients combined with friction to move beyond past experience. The turbine disk/blade assembly configuration contributed to the potential for these problems to occur by limiting the radial deflection from thermals and centrifugal loading. The cooled solid bore configuration was chosen to improve rotordynamic stability by limiting the length of rotor overhang while still protecting the roller bearing by maintaining zero slope under the inner race. During a start transient, the rim area of the disk heats rapidly and expands axially and circumferentially and requires corresponding radial and axial growth of the disk to maintain relative positioning of the disk, blades, spacers and retainer rings. The stiffness, large thermal mass, and bore cooling flow combine to severely limit the disk rim radial growth which results in the potential for relative movement between these parts. Friction then becomes a player in the determination of component stress.

A method for turbine blade temperature data segmentation

NASA Astrophysics Data System (ADS)

Feng, Chi; Wang, Li; Gao, Shan

2017-08-01

Turbine blade, as one of the key components of the engine, operates in the badly working conditions. In order to better monitor the temperature status of turbine blades, research on temperature distribution of working blades is significant. The paper applies discrete Fourier transform to develop mathematical models, and the changes of period and peaks are summarized. The changing trends of temperature are reflected in each blade. The trends can be treated as one of the bases of the blade condition monitoring and fault diagnosis.

Channel flow analysis. [velocity distribution throughout blade flow field

NASA Technical Reports Server (NTRS)

Katsanis, T.

1973-01-01

The design of a proper blade profile requires calculation of the blade row flow field in order to determine the velocities on the blade surfaces. An analysis theory is presented for several methods used for this calculation and associated computer programs that were developed are discussed.

Bird impact analysis package for turbine engine fan blades

NASA Technical Reports Server (NTRS)

Hirschbein, M. S.

1982-01-01

A computer program has been developed to analyze the gross structural response of turbine engine fan blades subjected to bird strikes. The program couples a NASTRAN finite element model and modal analysis of a fan blade with a multi-mode bird impact analysis computer program. The impact analysis uses the NASTRAN blade model and a fluid jet model of the bird to interactively calculate blade loading during a bird strike event. The analysis package is computationaly efficient, easy to use and provides a comprehensive history of the gross structual blade response. Example cases are presented for a representative fan blade.

A conjugate heat transfer procedure for gas turbine blades.

PubMed

Croce, G

2001-05-01

A conjugate heat transfer procedure, allowing for the use of different solvers on the solid and fluid domain(s), is presented. Information exchange between solid and fluid solution is limited to boundary condition values, and this exchange is carried out at any pseudo-time step. Global convergence rate of the procedure is, thus, of the same order of magnitude of stand-alone computations.

Demonstration of an elastically coupled twist control concept for tilt rotor blade application

NASA Technical Reports Server (NTRS)

Lake, R. C.; Nixon, M. W.; Wilbur, M. L.; Singleton, J. D.; Mirick, P. H.

1994-01-01

The purpose of this Note is to present results from an analytic/experimental study that investigated the potential for passively changing blade twist through the use of extension-twist coupling. A set of composite model rotor blades was manufactured from existing blade molds for a low-twist metal helicopter rotor blade, with a view toward establishing a preliminary proof concept for extension-twist-coupled rotor blades. Data were obtained in hover for both a ballasted and unballasted blade configuration in sea-level atmospheric conditions. Test data were compared with results obtained from a geometrically nonlinear analysis of a detailed finite element model of the rotor blade developed in MSC/NASTRAN.

Development of Virtual Blade Model for Modelling Helicopter Rotor Downwash in OpenFOAM

DTIC Science & Technology

2013-12-01

UNCLASSIFIED Development of Virtual Blade Model for Modelling Helicopter Rotor Downwash in OpenFOAM Stefano Wahono Aerospace...Georgia Institute of Technology. The OpenFOAM predicted result was also shown to compare favourably with ANSYS Fluent predictions. RELEASE...UNCLASSIFIED Development of Virtual Blade Model for Modelling Helicopter Rotor Downwash in OpenFOAM Executive Summary The Infrared

WIND- THREE DIMENSIONAL POTENTIAL COMPRESSIBLE FLOW ABOUT WIND TURBINE ROTOR BLADES

NASA Technical Reports Server (NTRS)

Dulikravich, D. S.

1994-01-01

This computer program, WIND, was developed to numerically solve the exact, full-potential equation for three-dimensional, steady, inviscid flow through an isolated wind turbine rotor. The program automatically generates a three-dimensional, boundary-conforming grid and iteratively solves the full-potential equation while fully accounting for both the rotating and Coriolis effects. WIND is capable of numerically analyzing the flow field about a given blade shape of the horizontal-axis type wind turbine. The rotor hub is assumed representable by a doubly infinite circular cylinder. An arbitrary number of blades may be attached to the hub and these blades may have arbitrary spanwise distributions of taper and of the twist, sweep, and dihedral angles. An arbitrary number of different airfoil section shapes may be used along the span as long as the spanwise variation of all the geometeric parameters is reasonably smooth. The numerical techniques employed in WIND involve rotated, type-dependent finite differencing, a finite volume method, artificial viscosity in conservative form, and a successive overrelaxation combined with the sequential grid refinement procedure to accelerate the iterative convergence rate. Consequently, WIND is cabable of accurately analyzing incompressible and compressible flows, including those that are locally transonic and terminated by weak shocks. Along with the three-dimensional results, WIND provides the results of the two-dimensional calculations to aid the user in locating areas of possible improvement in the aerodynamic design of the blade. Output from WIND includes the chordwise distribution of the coefficient of pressure, the Mach number, the density, and the relative velocity components at spanwise stations along the blade. In addition, the results specify local values of the lift coefficient and the tangent and axial aerodynamic force components. These are also given in integrated form expressing the total torque and the total axial force acting on the shaft. WIND can also be used to analyze the flow around isolated aircraft propellers and helicopter rotors in hover as long as the relative oncoming flow is subsonic. The WIND program is written in FORTRAN IV for batch execution and has been implemented on an IBM 370 series computer with a central memory requirement of approximately 253K of 8 bit bytes. WIND was developed in 1980.

Development of a Pressure Sensitive Paint System for Measuring Global Surface Pressures on Rotorcraft Blades

NASA Technical Reports Server (NTRS)

Watkins, A. Neal; Leighty, Bradley D.; Lipford, William E.; Wong, Oliver D.; Oglesby, Donald M.; Ingram, JoAnne L.

2007-01-01

This paper will describe the results from a proof of concept test to examine the feasibility of using Pressure Sensitive Paint (PSP) to measure global surface pressures on rotorcraft blades in hover. The test was performed using the U.S. Army 2-meter Rotor Test Stand (2MRTS) and 15% scale swept rotor blades. Data were collected from five blades using both the intensity- and lifetime-based approaches. This paper will also outline several modifications and improvements that are underway to develop a system capable of measuring pressure distributions on up to four blades simultaneously at hover and forward flight conditions.

Development of an imaging system for the detection of alumina on turbine blades

NASA Astrophysics Data System (ADS)

Greenwell, S. J.; Kell, J.; Day, J. C. C.

2014-03-01

An imaging system capable of detecting alumina on turbine blades by acquiring LED-induced fluorescence images has been developed. Acquiring fluorescence images at adjacent spectral bands allows the system to distinguish alumina from fluorescent surface contaminants. Repair and overhaul processes require that alumina is entirely removed from the blades by grit blasting and chemical stripping. The capability of the system to detect alumina has been investigated with two series of turbine blades provided by Rolls-Royce plc. The results illustrate that the system provides a superior inspection method to visual assessment when ascertaining whether alumina is present on turbine blades during repair and overhaul processes.

LAM-1 and FAT Genes Control Development of the Leaf Blade in Nicotiana sylvestris.

PubMed Central

McHale, NA

1993-01-01

Leaf primordia of the lam-1 mutant of Nicotiana sylvestris grow normally in length but remain bladeless throughout development. The blade initiation site is established at the normal time and position in lam-1 primordia. Anticlinal divisions proceed normally in the outer L1 and L2 layers, but the inner L3 cells fail to establish the periclinal divisions that normally generate the middle mesophyll core. The lam-1 mutation also blocks formation of blade mesophyll from distal L2 cells. This suggests that LAM-1 controls a common step in initiation of blade tissue from the L2 and L3 lineage of the primordium. Another recessive mutation (fat) was isolated in N. sylvestris that induces abnormal periclinal divisions in the mesophyll during blade initiation and expansion. This generates a blade approximately twice its normal thickness by doubling the number of mesophyll cell layers from four to approximately eight. Presumably, the fat mutation defines a negative regulator involved in repression of periclinal divisions in the blade. The lam-1 fat double mutant shows radial proliferation of mesophyll cells at the blade initiation site. This produces a highly disorganized, club-shaped blade that appears to represent an additive effect of the lam-1 and fat mutations on blade founder cells. PMID:12271096

Structural integrity of wind tunnel wooden fan blades

NASA Technical Reports Server (NTRS)

Young, Clarence P., Jr.; Wingate, Robert T.; Rooker, James R.; Mort, Kenneth W.; Zager, Harold E.

1991-01-01

Information is presented which was compiled by the NASA Inter-Center Committee on Structural Integrity of Wooden Fan Blades and is intended for use as a guide in design, fabrication, evaluation, and assurance of fan systems using wooden blades. A risk assessment approach for existing NASA wind tunnels with wooden fan blades is provided. Also, state of the art information is provided for wooden fan blade design, drive system considerations, inspection and monitoring methods, and fan blade repair. Proposed research and development activities are discussed, and recommendations are provided which are aimed at future wooden fan blade design activities and safely maintaining existing NASA wind tunnel fan blades. Information is presented that will be of value to wooden fan blade designers, fabricators, inspectors, and wind tunnel operations personnel.

A proposed through-flow inverse method for the design of mixed-flow pumps

NASA Technical Reports Server (NTRS)

Borges, Joao Eduardo

1991-01-01

A through-flow (hub-to-shroud) truly inverse method is proposed and described. It uses an imposition of mean swirl, i.e., radius times mean tangential velocity, given throughout the meridional section of the turbomachine as an initial design specification. In the present implementation, it is assumed that the fluid is inviscid, incompressible, and irrotational at inlet and that the blades are supposed to have zero thickness. Only blade rows that impart to the fluid a constant work along the space are considered. An application of this procedure to design the rotor of a mixed-flow pump is described in detail. The strategy used to find a suitable mean swirl distribution and the other design inputs is also described. The final blade shape and pressure distributions on the blade surface are presented, showing that it is possible to obtain feasible designs using this technique. Another advantage of this technique is the fact that it does not require large amounts of CPU time.

Energy efficient engine high pressure turbine test hardware detailed design report

NASA Technical Reports Server (NTRS)

Halila, E. E.; Lenahan, D. T.; Thomas, T. T.

1982-01-01

The high pressure turbine configuration for the Energy Efficient Engine is built around a two-stage design system. Moderate aerodynamic loading for both stages is used to achieve the high level of turbine efficiency. Flowpath components are designed for 18,000 hours of life, while the static and rotating structures are designed for 36,000 hours of engine operation. Both stages of turbine blades and vanes are air-cooled incorporating advanced state of the art in cooling technology. Direct solidification (DS) alloys are used for blades and one stage of vanes, and an oxide dispersion system (ODS) alloy is used for the Stage 1 nozzle airfoils. Ceramic shrouds are used as the material composition for the Stage 1 shroud. An active clearance control (ACC) system is used to control the blade tip to shroud clearances for both stages. Fan air is used to impinge on the shroud casing support rings, thereby controlling the growth rate of the shroud. This procedure allows close clearance control while minimizing blade tip to shroud rubs.

Wind energy converter with high-speed vertical axis rotor and straight rotor blades

NASA Astrophysics Data System (ADS)

Zelck, G.

1982-11-01

Complete documents for a wind energy converter with a vertical axis rotor and straight blades (H-rotor) were developed. The 2 blade rotor with rigid and rectangular air foils in wooden construction reaches the nominal output of 75 KVA from 11,4 m/sec. wind velocity onwards. The development activities are supported by wind tunnel and component tests. The final design selected was based upon previous development work. Trade offs show that the design is more advantageous compared to other designs. The use of wood as a material for the rotary and horizontal blade supports gives positive result.

Theoretical performance of cross-wind axis turbines with results for a catenary vertical axis configuration

NASA Technical Reports Server (NTRS)

Muraca, R. J.; Stephens, M. V.; Dagenhart, J. R.

1975-01-01

A general analysis capable of predicting performance characteristics of cross-wind axis turbines was developed, including the effects of airfoil geometry, support struts, blade aspect ratio, windmill solidity, blade interference and curved flow. The results were compared with available wind tunnel results for a catenary blade shape. A theoretical performance curve for an aerodynamically efficient straight blade configuration was also presented. In addition, a linearized analytical solution applicable for straight configurations was developed. A listing of the computer program developed for numerical solutions of the general performance equations is included in the appendix.

Development of a Noninterference Technique for Measurement of Turbine Engine Compressor Blade Stress

DTIC Science & Technology

1980-06-01

TECHNIQUE FOR MEASUREMENT OF TURBINE ENGINE COMPRESSOR BLADE STRESS 7 A U T H O R ( s ) P . E. M c C a r t y a n d J . W. Thompson , J r...e a e a ~ and tdentJ~ by b|ock numbe~ A noninterference technique for measuring stress in compressor blades of turbine engines is being developed...43 4 AEDC-TR-79-78 1.0 INTRODUCTION 1.1 BACKGROUND Compressor rotor blades in turbojet engines are subjected to

An Assessment of the Icing Blade and the SEA Multi-Element Sensor for Liquid Water Content Calibration of the NASA GRC Icing Research Tunnel

NASA Technical Reports Server (NTRS)

Steen, Laura E.; Ide, Robert F.; Van Zante, Judith F.

2016-01-01

The Icing Research Tunnel at NASA Glenn has recently switched from using the Icing Blade to using the SEA Multi-Element Sensor (also known as the multi-wire) for its calibration of cloud liquid water content. In order to peform this transition, tests were completed to compare the Multi-Element Sensor to the Icing Blade, particularly with respect to liquid water content, airspeed, and drop size. The two instruments were found to compare well for the majority of Appendix C conditions. However, it was discovered that the Icing Blade under-measures when the conditions approach the Ludlam Limit. This paper also describes data processing procedures for the Multi-Element Sensor in the IRT, including collision efficiency corrections, mounting underneath a splitter plate, and correcting for a jump in the compensation wire power. Further data is presented to describe the repeatability of the IRT with the Multi-Element Sensor, health-monitoring checks for the instrument, and a sensing-element configuration comparison. Ultimately these tests showed that in the IRT, the multi-wire is a better instrument for measuring cloud liquid water content than the blade.

Full three-dimensional investigation of structural contact interactions in turbomachines

NASA Astrophysics Data System (ADS)

Legrand, Mathias; Batailly, Alain; Magnain, Benoît; Cartraud, Patrice; Pierre, Christophe

2012-05-01

Minimizing the operating clearance between rotating bladed-disks and stationary surrounding casings is a primary concern in the design of modern turbomachines since it may advantageously affect their energy efficiency. This technical choice possibly leads to interactions between elastic structural components through direct unilateral contact and dry friction, events which are now accepted as normal operating conditions. Subsequent nonlinear dynamical behaviors of such systems are commonly investigated with simplified academic models mainly due to theoretical difficulties and numerical challenges involved in non-smooth large-scale realistic models. In this context, the present paper introduces an adaptation of a full three-dimensional contact strategy for the prediction of potentially damaging motions that would imply highly demanding computational efforts for the targeted aerospace application in an industrial context. It combines a smoothing procedure including bicubic B-spline patches together with a Lagrange multiplier based contact strategy within an explicit time-marching integration procedure preferred for its versatility. The proposed algorithm is first compared on a benchmark configuration against the more elaborated bi-potential formulation and the commercial software Ansys. The consistency of the provided results and the low energy fluctuations of the introduced approach underlines its reliable numerical properties. A case study featuring blade-tip/casing contact on industrial finite element models is then proposed: it incorporates component mode synthesis and the developed three-dimensional contact algorithm for investigating structural interactions occurring within a turbomachine compressor stage. Both time results and frequency-domain analysis emphasize the practical use of such a numerical tool: detection of severe operating conditions and critical rotational velocities, time-dependent maps of stresses acting within the structures, parameter studies and blade design tests.

Development of Static Balance Measurement and Correction Compound Platform for Single Blade of Controllable Pitch Propeller

NASA Astrophysics Data System (ADS)

Chao, Zhang; Shijie, Su; Yilin, Yang; Guofu, Wang; Chao, Wang

2017-11-01

Aiming at the static balance of the controllable pitch propeller (CPP), a high efficiency static balance method based on the double-layer structure of the measuring table and gantry robot is adopted to realize the integration of torque measurement and corrected polish for controllable pitch propeller blade. The control system was developed by Microsoft Visual Studio 2015, and a composite platform prototype was developed. Through this prototype, conduct an experiment on the complete process of torque measurement and corrected polish based on a 300kg class controllable pitch propeller blade. The results show that the composite platform can correct the static balance of blade with a correct, efficient and labor-saving operation, and can replace the traditional method on static balance of the blade.

User satisfaction and forces generated during laryngoscopy using disposable Miller blades: a manikin study.

PubMed

Sudhir, G; Wilkes, A R; Clyburn, P; Aguilera, I; Hall, J E

2007-10-01

Increasing awareness of prion-related diseases has led to an increase in the number of disposable laryngoscope blades available. We compared 11 disposable and standard re-usable Miller size 1 blades. In this manikin-based study, we studied user satisfaction for field of view at laryngoscopy, build quality and users' willingness to use the blade in an emergency situation. These were found to be better with metal disposable blades (p

The SNL100-03 Blade: Design Studies with Flatback Airfoils for the Sandia 100-meter Blade.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Griffith, Daniel; Richards, Phillip William

A series of design studies were performed to inv estigate the effects of flatback airfoils on blade performance and weight for large blades using the Sandi a 100-meter blade designs as a starting point. As part of the study, the effects of varying the blade slenderness on blade structural performance was investigated. The advantages and disadvantages of blad e slenderness with respect to tip deflection, flap- wise & edge-wise fatigue resistance, panel buckling capacity, flutter speed, manufacturing labor content, blade total weight, and aerodynamic design load magn itude are quantified. Following these design studies, a final blade design (SNL100-03) wasmore » prod uced, which was based on a highly slender design using flatback airfoils. The SNL100-03 design with flatback airfoils has weight of 49 tons, which is about 16% decrease from its SNL100-02 predecessor that used conventional sharp trailing edge airfoils. Although not systematically optimized, the SNL100 -03 design study provides an assessment of and insight into the benefits of flatback airfoils for la rge blades as well as insights into the limits or negative consequences of high blade slenderness resulting from a highly slender SNL100-03 planform as was chosen in the final design definition. This docum ent also provides a description of the final SNL100-03 design definition and is intended to be a companion document to the distribution of the NuMAD blade model files for SNL100-03, which are made publicly available. A summary of the major findings of the Sandia 100-meter blade development program, from the initial SNL100-00 baseline blade through the fourth SNL100-03 blade study, is provided. This summary includes the major findings and outcomes of blade d esign studies, pathways to mitigate the identified large blade design drivers, and tool development that were produced over the course of this five-year research program. A summary of large blade tec hnology needs and research opportunities is also presented.« less

Microcomputer monitor system and device for non-touch measurement of turbine blade vibration

NASA Astrophysics Data System (ADS)

Zheng, Shu-Chen; Liu, Bo; Qu, Zhi-Huan; Din, Ke-Ke

To study the aeroelastic phenomena in turbomachinery, a microcomputer monitor system and device for nonintrusive measurement of turbine blade vibration is developed. The system can continuously measure blade amplitude of vibration, phase angle, and torsional angle, when the machinery blades encounter vibration. In the case of turbine operation, it can display and print the vibrating parameters measured by the system, automatically give out the warning when blade amplitude of vibration is bigger than safety value, or blades break. The vibrating parameters in a span of time before the break occurs is recorded. A forecast is produced as blades enter the flutter boundary.

Prediction of SA 349/2 GV blade loads in high speed flight using several rotor analyses

NASA Technical Reports Server (NTRS)

Gaubert, Michel; Yamauchi, Gloria K.

1987-01-01

The influence of blade dynamics, dynamic stall, and transonic aerodynamics on the predictions of rotor loads in high-speed flight are presented. Data were obtained from an Aerospatiale Gazelle SA 349/2 helicopter with three Grande Vitesse blades. Several analyses are used for this investigation. First, blade dynamics effects on the correlation are studied using three rotor analyses which differ mainly in the method of calculating the blade elastic response. Next, an ONERA dynamic stall model is used to predict retreating blade stall. Finally, advancing blade aerodynamic loads are calculated using a NASA-developed rotorcraft analysis coupled with two transonic finite-difference analyses.

Three dimensional mean velocity and turbulence characteristics in the annulus wall region of an axial flow compressor rotor passage

NASA Technical Reports Server (NTRS)

Davino, R.; Lakshminarayana, B.

1982-01-01

The experiment was performed using the rotating hot-wire technique within the rotor blade passage and the stationary hot-wire technique for the exitflow of the rotor blade passage. The measurements reveal the effect of rotation and subsequent flow interactions upon the rotor blade flowfield and wake development in the annulus-wall region. The flow near the rotor blade tips is found to be highly complex due to the interaction of the annulus-wall boundary layer, the blade boundary layers, the tip leakage flow, and the secondary flow. Within the blade passage, this interaction results in an appreciable radial inward flow as well as a defect in the mainstream velocity near the mid-passage. Turbulence levels within this region are very high. This indicates a considerable extent of flow mixing due to the viscous flow interactions. The size and strength of this loss core is found to grow with axial distance from the blade trailing edge. The nature of the rotor blade exit-flow was dominated by the wake development.

Studies of blade-vortex interaction noise reduction by rotor blade modification

NASA Technical Reports Server (NTRS)

Brooks, Thomas F.

1993-01-01

Blade-vortex interaction (BVI) noise is one of the most objectionable types of helicopter noise. This impulsive blade-slap noise can be particularly intense during low-speed landing approach and maneuvers. Over the years, a number of flight and model rotor tests have examined blade tip modification and other blade design changes to reduce this noise. Many times these tests have produced conflicting results. In the present paper, a number of these studies are reviewed in light of the current understanding of the BVI noise problem. Results from one study in particular are used to help establish the noise reduction potential and to shed light on the role of blade design. Current blade studies and some new concepts under development are also described.

Novel casting processes for single-crystal turbine blades of superalloys

NASA Astrophysics Data System (ADS)

Ma, Dexin

2018-03-01

This paper presents a brief review of the current casting techniques for single-crystal (SC) blades, as well as an analysis of the solidification process in complex turbine blades. A series of novel casting methods based on the Bridgman process were presented to illustrate the development in the production of SC blades from superalloys. The grain continuator and the heat conductor techniques were developed to remove geometry-related grain defects. In these techniques, the heat barrier that hinders lateral SC growth from the blade airfoil into the extremities of the platform is minimized. The parallel heating and cooling system was developed to achieve symmetric thermal conditions for SC solidification in blade clusters, thus considerably decreasing the negative shadow effect and its related defects in the current Bridgman process. The dipping and heaving technique, in which thinshell molds are utilized, was developed to enable the establishment of a high temperature gradient for SC growth and the freckle-free solidification of superalloy castings. Moreover, by applying the targeted cooling and heating technique, a novel concept for the three-dimensional and precise control of SC growth, a proper thermal arrangement may be dynamically established for the microscopic control of SC growth in the critical areas of large industrial gas turbine blades.

Tiltrotor Research Aircraft composite blade repairs - Lessons learned

NASA Technical Reports Server (NTRS)

Espinosa, Paul S.; Groepler, David R.

1992-01-01

The XV-15, N703NA Tiltrotor Research Aircraft located at the NASA Ames Research Center, Moffett Field, California, currently uses a set of composite rotor blades of complex shape known as the advanced technology blades (ATBs). The main structural element of the blades is a D-spar constructed of unidirectional, angled fiberglass/graphite, with the aft fairing portion of the blades constructed of a fiberglass cross-ply skin bonded to a Nomex honeycomb core. The blade tip is a removable laminate shell that fits over the outboard section of the spar structure, which contains a cavity to retain balance weights. Two types of tip shells are used for research. One is highly twisted (more than a conventional helicopter blade) and has a hollow core constructed of a thin Nomex-honeycomb-and-fiberglass-skin sandwich; the other is untwisted with a solid Nomex honeycomb core and a fiberglass cross-ply skin. During initial flight testing of the blades, a number of problems in the composite structure were encountered. These problems included debonding between the fiberglass skin and the honeycomb core, failure of the honeycomb core, failures in fiberglass splices, cracks in fiberglass blocks, misalignment of mated composite parts, and failures of retention of metal fasteners. Substantial time was spent in identifying and repairing these problems. Discussed here are the types of problems encountered, the inspection procedures used to identify each problem, the repairs performed on the damaged or flawed areas, the level of criticality of the problems, and the monitoring of repaired areas. It is hoped that this discussion will help designers, analysts, and experimenters in the future as the use of composites becomes more prevalent.

Tiltrotor research aircraft composite blade repairs: Lessons learned

NASA Technical Reports Server (NTRS)

Espinosa, Paul S.; Groepler, David R.

1991-01-01

The XV-15, N703NA Tiltrotor Research Aircraft located at the NASA Ames Research Center, Moffett Field, California, currently uses a set of composite rotor blades of complex shape known as the advanced technology blades (ATBs). The main structural element of the blades is a D-spar constructed of unidirectional, angled fiberglass/graphite, with the aft fairing portion of the blades constructed of a fiberglass cross-ply skin bonded to a Nomex honeycomb core. The blade tip is a removable laminate shell that fits over the outboard section of the spar structure, which contains a cavity to retain balance weights. Two types of tip shells are used for research. One is highly twisted (more than a conventional helicopter blade) and has a hollow core constructed of a thin Nomex-honeycomb-and-fiberglass-skin sandwich; the other is untwisted with a solid Nomex honeycomb core and a fiberglass cross-ply skin. During initial flight testing of the blades, a number of problems in the composite structure were encountered. These problems included debonding between the fiberglass skin and the honeycomb core, failure of the honeycomb core, failures in fiberglass splices, cracks in fiberglass blocks, misalignment of mated composite parts, and failures of retention of metal fasteners. Substantial time was spent in identifying and repairing these problems. Discussed here are the types of problems encountered, the inspection procedures used to identify each problem, the repairs performed on the damaged or flawed areas, the level of criticality of the problems, and the monitoring of repaired areas. It is hoped that this discussion will help designers, analysts, and experimenters in the future as the use of composites becomes more prevalent.

Bacterial Contamination and Disinfection Status of Laryngoscopes Stored in Emergency Crash Carts

PubMed Central

Lee, Jung Won; Shin, Hee Bong; Lee, In Kyung

2017-01-01

Objectives To identify bacterial contamination rates of laryngoscope blades and handles stored in emergency crash carts by hospital and area according to the frequency of intubation attempts. Methods One hundred forty-eight handles and 71 blades deemed ready for patient use from two tertiary hospitals were sampled with sterile swabs using a standardized rolling technique. Samples were considered negative (not contaminated) if no colonies were present on the blood agar plate after an 18-hour incubation period. Samples were stratified by hospital and according to the frequency of intubation attempts (10 attempts per year) using the χ2-test and Fisher exact test. Results One or more species of bacteria were isolated from 4 (5.6%) handle tops, 20 (28.2%) handles with knurled surfaces, and 27 (18.2%) blades. No significant differences were found in microbial contamination levels on the handle tops and blades between the two hospitals and two areas according to the frequency of intubation attempts. However, significant differences were found between the two hospitals and two areas in the level of microbial contamination on the handles with knurled surfaces (p<0.05). Conclusions Protocols and policies must be reviewed to standardize procedures to clean and disinfect laryngoscope blades and handles; handles should be re-designed to eliminate points of contact with the blade; and single-use, one-piece laryngoscopes should be introduced. PMID:28605891

Development of an experimental setup for testing the properties of γ/γ' superalloys

NASA Astrophysics Data System (ADS)

Christophe, Siret; Bernard, Viguier; Claude, Salabura Jean; Eric, Andrieu; Sandrine, Lesterlin

2010-07-01

Certification tests on turboshaft engines for helicopters can expose components as high pressure turbine blades to very high temperature during short time periods. To simulate these complex temperature and mechanical stress loadings and to study dimensional and microstructural stability under severe testing conditions, an experimental set-up has been recently developed. In this paper, we first present this new device and describe its performances. Then, the device is used to study the effect of heating procedure on creep results at 1200°C and rafting during primary creep on the single crystal nickel-based superalloy MC2.

Non-invasive dynamic measurement of helicopter blades

NASA Astrophysics Data System (ADS)

Serafini, J.; Bernardini, G.; Mattioni, L.; Vezzari, V.; Ficuciello, C.

2017-08-01

This paper presents the development and the application on helicopter blades of a measurement system based on FBG strain gauges. Here, the main goal is the structural characterization of the main rotor blades, with the aim of showing the potentialities of such a system in blades quality check applications, as well as in the development of structural health monitoring and rotor state feedback devices. The device has been used in both non-rotating and rotating tests, and does not require the presence of slip rings or optical joint since it is completely allocated in the rotating system. It has been successfully applied to characterize the frequency response of blades lead-lag, flap and torsion deformations, up to 250 Hz.

Modeling the Elastic and Damping Properties of the Multilayered Torsion Bar-Blade Structure of Rotors of Light Helicopters of the New Generation 2. Finite-Element Approximation of Blades and a Model of Coupling of the Torsion Bar with the Blades

NASA Astrophysics Data System (ADS)

Paimushin, V. N.; Shishkin, V. M.

2016-01-01

A rod-shape finite element with twelve degrees of freedom is proposed for modeling the elastic and damping properties of rotor blades with regard to their geometric stiffness caused by rotation of the rotor. A model of coupling of the torsion bar with blades is developed based on the hypothesis of linear deplanation of the connecting section of the torsion bar and a special transition element to ensure the compatibility of displacements of the torsion bar and blades upon their vibrations in the flapping and rotation planes. Numerical experiments were carried out to test and assess the validity of the model developed. Suggestions are made for ensuring unconditional stability of the iteration method in a subspace in determining the specified number of modes and frequencies of free vibrations of the torsion bar-blade structure.

An aerodynamic study on flexed blades for VAWT applications

NASA Astrophysics Data System (ADS)

Micallef, Daniel; Farrugia, Russell; Sant, Tonio; Mollicone, Pierluigi

2014-12-01

There is renewed interest in aerodynamics research of VAWT rotors. Lift type, Darrieus designs sometimes use flexed blades to have an 'egg-beater shape' with an optimum Troposkien geometry to minimize the structural stress on the blades. While straight bladed VAWTs have been investigated in depth through both measurements and numerical modelling, the aerodynamics of flexed blades has not been researched with the same level of detail. Two major effects may have a substantial impact on blade performance. First, flexing at the equator causes relatively strong trailing vorticity to be released. Secondly, the blade performance at each station along the blade is influenced by self-induced velocities due to bound vorticity. The latter is not present in a straight bladed configuration. The aim of this research is to investigate these effects in relation to an innovative 4kW wind turbine concept being developed in collaboration with industry known as a self-adjusting VAWT (or SATVAWT). The approach used in this study is based on experimental and numerical work. A lifting line free-wake vortex model was developed. Wind tunnel power and hot-wire velocity measurements were performed on a scaled down, 60cm high, three bladed model in a closed wind tunnel. Results show a substantial axial wake induction at the equator resulting in a lower power generation at this position. This induction increases with increasing degree of flexure. The self-induced velocities caused by blade bound vorticity at a particular station was found to be relatively small.

SSME HPFTP/AT Turbine Blade Platform Featherseal Damper Design

NASA Technical Reports Server (NTRS)

Montgomery, S. K.

1999-01-01

During the Space Shuttle Main Engines (SSM) HPFtP/AT development program, engine hot fire testing resulted in turbine blade fatigue cracks. The cracks were noted after only a few tests and a several hundred seconds versus the design goal of 60 tests and >30,000 seconds. Subsequent investigation attributed the distress to excessive steady and dynamic loads. To address these excessive turbine blade loads, Pratt & Whitney Liquid Space Propulsion engineers designed and developed retrofitable turbine blade to blade platform featherseal dampers. Since incorporation of these dampers, along with other turbine blade system improvements, there has been no observed SSME HPFTP/AT turbine blade fatigue cracking. The high time HPFTP/AT blade now has accumulated 32 starts and 19,200 seconds hot fire test time. Figure #1 illustrates the HPFTP/AT turbine blade platform featherseal dampers. The approached selected was to improve the turbine blade structural capability while simultaneously reducing loads. To achieve this goal, the featherseal dampers were designed to seal the blade to blade platform gap and damp the dynamic motions. Sealing improves the steady stress margins by increasing turbine efficiency and improving turbine blade attachment thermal conditioning. Load reduction was achieved through damping. Thin Haynes 188 sheet metal was selected based on its material properties (hydrogen resistance, elongation, tensile strengths, etc.). The 36,000 rpm wheel speed of the rotor result in a normal load of 120#/blade. The featherseals then act as micro-slip dampers during actual SSME operation. After initial design and analysis (prior to full engine testing), the featherseal dampers were tested in P&W's spin rig facility in West Palm Beach, Florida. Both dynamic strain gages and turbine blade tip displacement measurements were utilized to quantify the featherseal damper effectiveness. Full speed (36,000 rpm), room temperature rig testing verified the elimination of fundamental mode (i.e, modes 1 & 2) resonant response. The reduction in turbine blade dynamic response is shown for a typical turbine blade. This paper discusses the design and verification of these dampers. The numerous benefits associated with this design concept warrants consideration in existing and future turbomachinery applications.

Application of Out-of-Plane Warping to Control Rotor Blade Twist

NASA Technical Reports Server (NTRS)

VanWeddingen, Yannick; Bauchau, Olivier; Kottapalli, Sesi; Ozbay, Serkan; Mehrotra, Yogesh

2012-01-01

The goal of this ongoing study is to develop and demonstrate the feasibility of a blade actuation system to dynamically change the twist, and/or the camber, of an airfoil section and, consequently, alter the in-flight aerodynamic loading on the blade for efficient flight control. The required analytical and finite element tools are under development to enable an accurate and comprehensive aeroelastic assessment of the current Full-Blade Warping and 3D Warping Actuated Trailing Edge Flap concepts. The feasibility of the current concepts for swashplateless rotors and higher harmonic blade control is also being investigated. In particular, the aim is to complete the following objectives, some of which have been completed (as noted below) and others that are currently ongoing: i) Develop a Vlasov finite element model and validate against the ABAQUS shell models (completed). ii) Implement the 3D warping actuation concept within the comprehensive analysis code DYMORE. iii) Perform preliminary aeroelastic simulations of blades using DYMORE with 3D warping actuation: a) Investigate the blade behavior under 1 per/rev actuation. Determine whether sufficient twist can be generated and sustained to achieve primary blade control. b) Investigate the behavior of a trailing edge flap configuration under higher harmonic excitations. Determine how much twist can be obtained at the harmonics 2-5 per/rev. iv) Determine actuator specifications such as the power required, load and displacements, and identify the stress and strain distributions in the actuated blades. In general, the completion of Item ii) above will give an additional research capability in rotorcraft dynamics analyses, i.e., the capability to calculate the rotor blade twist due to warping, something that is not currently available in any of the existing comprehensive rotorcraft analyses.

Composite load spectra for select space propulsion structural components

NASA Technical Reports Server (NTRS)

Newell, J. F.; Ho, H. W.; Kurth, R. E.

1991-01-01

The work performed to develop composite load spectra (CLS) for the Space Shuttle Main Engine (SSME) using probabilistic methods. The three methods were implemented to be the engine system influence model. RASCAL was chosen to be the principal method as most component load models were implemented with the method. Validation of RASCAL was performed. High accuracy comparable to the Monte Carlo method can be obtained if a large enough bin size is used. Generic probabilistic models were developed and implemented for load calculations using the probabilistic methods discussed above. Each engine mission, either a real fighter or a test, has three mission phases: the engine start transient phase, the steady state phase, and the engine cut off transient phase. Power level and engine operating inlet conditions change during a mission. The load calculation module provides the steady-state and quasi-steady state calculation procedures with duty-cycle-data option. The quasi-steady state procedure is for engine transient phase calculations. In addition, a few generic probabilistic load models were also developed for specific conditions. These include the fixed transient spike model, the poison arrival transient spike model, and the rare event model. These generic probabilistic load models provide sufficient latitude for simulating loads with specific conditions. For SSME components, turbine blades, transfer ducts, LOX post, and the high pressure oxidizer turbopump (HPOTP) discharge duct were selected for application of the CLS program. They include static pressure loads and dynamic pressure loads for all four components, centrifugal force for the turbine blade, temperatures of thermal loads for all four components, and structural vibration loads for the ducts and LOX posts.

Optimization of the blade trailing edge geometric parameters for a small scale ORC turbine

NASA Astrophysics Data System (ADS)

Zhang, L.; Zhuge, W. L.; Peng, J.; Liu, S. J.; Zhang, Y. J.

2013-12-01

In general, the method proposed by Whitfield and Baines is adopted for the turbine preliminary design. In this design procedure for the turbine blade trailing edge geometry, two assumptions (ideal gas and zero discharge swirl) and two experience values (WR and γ) are used to get the three blade trailing edge geometric parameters: relative exit flow angle β6, the exit tip radius R6t and hub radius R6h for the purpose of maximizing the rotor total-to-static isentropic efficiency. The method above is established based on the experience and results of testing using air as working fluid, so it does not provide a mathematical optimal solution to instruct the optimization of geometry parameters and consider the real gas effects of the organic, working fluid which must be taken into consideration for the ORC turbine design procedure. In this paper, a new preliminary design and optimization method is established for the purpose of reducing the exit kinetic energy loss to improve the turbine efficiency ηts, and the blade trailing edge geometric parameters for a small scale ORC turbine with working fluid R123 are optimized based on this method. The mathematical optimal solution to minimize the exit kinetic energy is deduced, which can be used to design and optimize the exit shroud/hub radius and exit blade angle. And then, the influence of blade trailing edge geometric parameters on turbine efficiency ηts are analysed and the optimal working ranges of these parameters for the equations are recommended in consideration of working fluid R123. This method is used to modify an existing ORC turbine exit kinetic energy loss from 11.7% to 7%, which indicates the effectiveness of the method. However, the internal passage loss increases from 7.9% to 9.4%, so the only way to consider the influence of geometric parameters on internal passage loss is to give the empirical ranges of these parameters, such as the recommended ranges that the value of γ is at 0.3 to 0.4, and the value of τ is at 0.5 to 0.6.

Darrieus rotor aerodynamics

NASA Astrophysics Data System (ADS)

Klimas, P. C.

1982-05-01

A summary of the progress of modeling the aerodynamic effects on the blades of a Darrieus wind turbine is presented. Interference is discussed in terms of blade/blade wake interaction and improvements in single and multiple stream tube models, of vortex simulations of blades and their wakes, and a hybrid momentum/vortex code to combine fast computation time with interference-describing capabilities. An empirical model has been developed for treating the properties of dynamic stall such as airfoil geometry, Reynolds number, reduced frequency, angle-of-attack, and Mach number. Pitching circulation has been subjected to simulation as potential flow about a two-dimensional flat plate, along with applications of the concepts of virtual camber and virtual incidence, with a cambered airfoil operating in a rectilinear flowfield. Finally, a need to develop a loading model suitable for nonsymmetrical blade sections is indicated, as well as blade behavior in a dynamic, curvilinear regime.

In-plane inertial coupling in tuned and severely mistuned bladed disks

NASA Technical Reports Server (NTRS)

Crawley, E. F.

1982-01-01

A model has been developed and verified for blade-disk-shaft coupling in rotors due to the in-plane rigid body modes of the disk. An analytic model has been developed which couples the in-plane rigid body modes of the disk on an elastic shaft with the blade bending modes. Bench resonance test were carried out on the M.I.T. Compressor Rotor, typical of research rotors with flexible blades and a thick rigid disk. When the rotor was carefully tuned, the structural coupling of the blades by the disks was confined to zero and one nodal diameter modes, whose modal frequencies were greater than the blade cantilever frequency. In the case of the tuned rotor, and in two cases where severe mistuning was intentionally introduced, agreement between the predicted and observed natural frequencies is excellent. The analytic model was then extended to include the effects of constant angular rotation of the disk.

Blade Displacement Measurements of the Full-Scale UH-60A Airloads Rotor

NASA Technical Reports Server (NTRS)

Barrows, Danny A.; Burner, Alpheus W.; Abrego, Anita I.; Olson, Lawrence E.

2011-01-01

Blade displacement measurements were acquired during a wind tunnel test of the full-scale UH-60A Airloads rotor. The test was conducted in the 40- by 80-Foot Wind Tunnel of the National Full-Scale Aerodynamics Complex at NASA Ames Research Center. Multi-camera photogrammetry was used to measure the blade displacements of the four-bladed rotor. These measurements encompass a range of test conditions that include advance ratios from 0.15 to unique slowed-rotor simulations as high as 1.0, thrust coefficient to rotor solidity ratios from 0.01 to 0.13, and rotor shaft angles from -10.0 to 8.0 degrees. The objective of these measurements is to provide a benchmark blade displacement database to be utilized in the development and validation of rotorcraft computational tools. The methodology, system development, measurement techniques, and preliminary sample blade displacement measurements are presented.

Radar-cross-section reduction of wind turbines. part 1.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brock, Billy C.; Loui, Hung; McDonald, Jacob J.

2012-03-05

In recent years, increasing deployment of large wind-turbine farms has become an issue of growing concern for the radar community. The large radar cross section (RCS) presented by wind turbines interferes with radar operation, and the Doppler shift caused by blade rotation causes problems identifying and tracking moving targets. Each new wind-turbine farm installation must be carefully evaluated for potential disruption of radar operation for air defense, air traffic control, weather sensing, and other applications. Several approaches currently exist to minimize conflict between wind-turbine farms and radar installations, including procedural adjustments, radar upgrades, and proper choice of low-impact wind-farm sites,more » but each has problems with limited effectiveness or prohibitive cost. An alternative approach, heretofore not technically feasible, is to reduce the RCS of wind turbines to the extent that they can be installed near existing radar installations. This report summarizes efforts to reduce wind-turbine RCS, with a particular emphasis on the blades. The report begins with a survey of the wind-turbine RCS-reduction literature to establish a baseline for comparison. The following topics are then addressed: electromagnetic model development and validation, novel material development, integration into wind-turbine fabrication processes, integrated-absorber design, and wind-turbine RCS modeling. Related topics of interest, including alternative mitigation techniques (procedural, at-the-radar, etc.), an introduction to RCS and electromagnetic scattering, and RCS-reduction modeling techniques, can be found in a previous report.« less

Ceramic thermal protective coating withstands hostile environment of rotating turbine blades

NASA Technical Reports Server (NTRS)

Liebert, C. H.; Stecura, S.

1975-01-01

Ceramic coatings have low thermal conductivity. They provide potential for increased engine performance, reduced fuel consumption, use of less costly materials or construction procedures, and increased life and durability.

Field Telemetry of Blade-rotor Coupled Torsional Vibration at Matuura Power Station Number 1 Unit

NASA Technical Reports Server (NTRS)

Isii, Kuniyoshi; Murakami, Hideaki; Otawara, Yasuhiko; Okabe, Akira

1991-01-01

The quasi-modal reduction technique and finite element model (FEM) were used to construct an analytical model for the blade-rotor coupled torsional vibration of a steam turbine generator of the Matuura Power Station. A single rotor test was executed in order to evaluate umbrella vibration characteristics. Based on the single rotor test results and the quasi-modal procedure, the total rotor system was analyzed to predict coupled torsional frequencies. Finally, field measurement of the vibration of the last stage buckets was made, which confirmed that the double synchronous resonance was 124.2 Hz, meaning that the machine can be safely operated. The measured eigen values are very close to the predicted value. The single rotor test and this analytical procedure thus proved to be a valid technique to estimate coupled torsional vibration.

From the Start: NREL Nurtures a Growing Wind Industry - Continuum

Science.gov Websites

failures common in the field, the wind industry developed a standard practice for all wind turbine blades priorities was to build a mechanical testing facility for wind turbine blades. Blade testing began in 1989 blades to the breaking point in the past quarter century. Watch the video to learn more about the

A laser-optical sensor system for blade vibration detection of high-speed compressors

NASA Astrophysics Data System (ADS)

Neumann, Mathias; Dreier, Florian; Günther, Philipp; Wilke, Ulrich; Fischer, Andreas; Büttner, Lars; Holzinger, Felix; Schiffer, Heinz-Peter; Czarske, Jürgen

2015-12-01

Improved efficiency as well as increased lifetime of turbines and compressors are important goals in turbomachinery development. A significant enhancement to accomplish these aims can be seen in online monitoring of the operating parameters of the machines. During the operation of compressors it is of high interest to predict critical events like flutter or stall which can be achieved by observing blade deformations and vibrations. We have developed a laser Doppler distance sensor (LDDS), which is capable of simultaneously measuring the radial blade expansions, the circumferential blade deflections as well as the circumferential velocities of the rotor blade tips. As a result, an increase of blade vibrations is measured before stall at characteristic frequencies. While the detected vibration frequencies and the vibration increase are in agreement with the measurement results of a commercial capacitive blade tip timing system, the measured values of the vibration amplitudes differ by a factor of three. This difference can be mainly attributed to the different measurement locations and to the different measurement approaches. Since the LDDS is applicable to metal as well as ceramic, carbon-fiber and glass-fiber reinforced composite blades, a universally applicable sensor system for stall prediction and status monitoring is presented.

Active Blade Vibration Control Being Developed and Tested

NASA Technical Reports Server (NTRS)

Johnson, Dexter

2003-01-01

Gas turbine engines are currently being designed to have increased performance, lower weight and manufacturing costs, and higher reliability. Consequently, turbomachinery components, such as turbine and compressor blades, have designs that are susceptible to new vibration problems and eventual in-service failure due to high-cycle fatigue. To address this problem, researchers at the NASA Glenn Research Center are developing and testing innovative active blade vibration control concepts. Preliminary results of using an active blade vibration control system, involving a rotor supported by an active magnetic bearing in Glenn's Dynamic Spin Rig, indicate promising results (see the photograph). Active blade vibration control was achieved using feedback of blade strain gauge signals within the magnetic bearing control loop. The vibration amplitude was reduced substantially (see the graphs). Also, vibration amplitude amplification was demonstrated; this could be used to enhance structural mode identification, if desired. These results were for a nonrotating two-bladed disk. Tests for rotating blades are planned. Current and future active blade vibration control research is planned to use a fully magnetically suspended rotor and smart materials. For the fully magnetically suspended rotor work, three magnetic bearings (two radial and one axial) will be used as actuators instead of one magnetic bearing. This will allow additional degrees of freedom to be used for control. For the smart materials work, control effectors located on and off the blade will be considered. Piezoelectric materials will be considered for on-the-blade actuation, and actuator placement on a stator vane, or other nearby structure, will be investigated for off-the-blade actuation. Initial work will focus on determining the feasibility of these methods by performing basic analysis and simple experiments involving feedback control.

Evaluation of Aeroelastically Tailored Small Wind Turbine Blades Final Project Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Griffin, Dayton A.

2005-09-29

Evaluation of Aeroelastically Tailored Small Wind Turbine Blades Final Report Global Energy Concepts, LLC (GEC) has performed a conceptual design study concerning aeroelastic tailoring of small wind turbine blades. The primary objectives were to evaluate ways that blade/rotor geometry could be used to enable cost-of-energy reductions by enhancing energy capture while constraining or mitigating blade costs, system loads, and related component costs. This work builds on insights developed in ongoing adaptive-blade programs but with a focus on application to small turbine systems with isotropic blade material properties and with combined blade sweep and pre-bending/pre-curving to achieve the desired twist coupling.more » Specific goals of this project are to: (A) Evaluate and quantify the extent to which rotor geometry can be used to realize load-mitigating small wind turbine rotors. Primary aspects of the load mitigation are: (1) Improved overspeed safety affected by blades twisting toward stall in response to speed increases. (2) Reduced fatigue loading affected by blade twisting toward feather in response to turbulent gusts. (B) Illustrate trade-offs and design sensitivities for this concept. (C) Provide the technical basis for small wind turbine manufacturers to evaluate this concept and commercialize if the technology appears favorable. The SolidWorks code was used to rapidly develop solid models of blade with varying shapes and material properties. Finite element analyses (FEA) were performed using the COSMOS code modeling with tip-loads and centripetal accelerations. This tool set was used to investigate the potential for aeroelastic tailoring with combined planform sweep and pre-curve. An extensive matrix of design variables was investigated, including aerodynamic design, magnitude and shape of planform sweep, magnitude and shape of blade pre-curve, material stiffness, and rotor diameter. The FEA simulations resulted in substantial insights into the structural response of these blades. The trends were used to identify geometries and rotor configurations that showed the greatest promise for achieving beneficial aeroelastic response. The ADAMS code was used to perform complete aeroelastic simulations of selected rotor configurations; however, the results of these simulations were not satisfactory. This report documents the challenges encountered with the ADAMS simulations and presents recommendations for further development of this concept for aeroelastically tailored small wind turbine blades.« less

Manufacturing a 9-Meter Thermoplastic Composite Wind Turbine Blade: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murray, Robynne; Snowberg, David R; Berry, Derek S

Currently, wind turbine blades are manufactured from a combination of glass and/or carbon fiber composite materials with a thermoset resin such as epoxy, which requires energy-intensive and expensive heating processes to cure. Newly developed in-situ polymerizing thermoplastic resin systems for composite wind turbine blades polymerize at room temperature, eliminating the heating process and significantly reducing the blade manufacturing cycle time and embodied energy, which in turn reduces costs. Thermoplastic materials can also be thermally welded, eliminating the need for adhesive bonds between blade components and increasing the overall strength and reliability of the blades. As well, thermoplastic materials enable end-of-lifemore » blade recycling by reheating and decomposing the materials, which is a limitation of existing blade technology. This paper presents a manufacturing demonstration for a 9-m-long thermoplastic composite wind turbine blade. This blade was constructed in the Composites Manufacturing Education and Technology facility at the National Wind Technology Center at the National Renewable Energy Laboratory (NREL) using a vacuum-assisted resin transfer molding process. Johns Manville fiberglass and an Arkema thermoplastic resin called Elium were used. Additional materials included Armacell-recycled polyethylene terephthalate foam from Creative Foam and low-cost carbon- fiber pultruded spar caps (manufactured in collaboration with NREL, Oak Ridge National Laboratory, Huntsman, Strongwell, and Chomarat). This paper highlights the development of the thermoplastic resin formulations, including an additive designed to control the peak exothermic temperatures. Infusion and cure times of less than 3 hours are also demonstrated, highlighting the efficiency and energy savings associated with manufacturing thermoplastic composite blades.« less

Unsteady Pressures in a Transonic Fan Cascade Due to a Single Oscillating Airfoil

NASA Technical Reports Server (NTRS)

Lepicovsky, J.; McFarland, E. R.; Capece, V. R.; Hayden, J.

2002-01-01

An extensive set of unsteady pressure data was acquired along the midspan of a modern transonic fan blade for simulated flutter conditions. The data set was acquired in a nine-blade linear cascade with an oscillating middle blade to provide a database for the influence coefficient method to calculate instantaneous blade loadings. The cascade was set for an incidence of 10 dg. The data were acquired on three stationary blades on each side of the middle blade that was oscillated at an amplitude of 0.6 dg. The matrix of test conditions covered inlet Mach numbers of 0.5, 0.8, and 1.1 and the oscillation frequencies of 200, 300, 400, and 500 Hz. A simple quasiunsteady two-dimensional computer simulation was developed to aid in the running of the experimental program. For high Mach number subsonic inlet flows the blade pressures exhibit very strong, low-frequency, self-induced oscillations even without forced blade oscillations, while for low subsonic and supersonic inlet Mach numbers the blade pressure unsteadiness is quite low. The amplitude of forced pressure fluctuations on neighboring stationary blades strongly depends on the inlet Mach number and forcing frequency. The flowfield behavior is believed to be governed by strong nonlinear effects due to a combination of viscosity, compressibility, and unsteadiness. Therefore, the validity of the quasi-unsteady simplified computer simulation is limited to conditions when the flowfield is behaving in a linear, steady manner. Finally, an extensive set of unsteady pressure data was acquired to help development and verification of computer codes for blade flutter effects.

Effect of Reynolds number, turbulence level and periodic wake flow on heat transfer on low pressure turbine blades.

PubMed

Suslov, D; Schulz, A; Wittig, S

2001-05-01

The development of effective cooling methods is of major importance for the design of new gas turbines blades. The conception of optimal cooling schemes requires a detailed knowledge of the heat transfer processes on the blade's surfaces. The thermal load of turbine blades is predominantly determined by convective heat transfer which is described by the local heat transfer coefficient. Heat transfer is closely related to the boundary layer development along the blade surface and hence depends on various flow conditions and geometrical parameters. Particularly Reynolds number, pressures gradient and turbulence level have great impact on the boundary layer development and the according heat transfer. Therefore, in the present study, the influence of Reynolds number, turbulence intensity, and periodic unsteady inflow on the local heat transfer of a typical low pressure turbine airfoil is experimentally examined in a plane cascade.

Thermal Imaging of Medical Saw Blades and Guides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dinwiddie, Ralph Barton; Steffner, Thomas E

2007-01-01

Better Than New, LLC., has developed a surface treatment to reduce the friction and wear of orthopedic saw blades and guides. The medical saw blades were thermally imaged while sawing through fresh animal bone and an IR camera was used to measure the blade temperature as it exited the bone. The thermal performance of as-manufactured saw blades was compared to surface-treated blades, and a freshly used blade was used for temperature calibration purposes in order to account for any emissivity changes due to organic transfer layers. Thermal imaging indicates that the treated saw blades cut faster and cooler than untreatedmore » blades. In orthopedic surgery, saw guides are used to perfectly size the bone to accept a prosthesis. However, binding can occur between the blade and guide because of misalignment. This condition increases the saw blade temperature and may result in tissue damage. Both treated ad untreated saw guides were also studied. The treated saw guide operated at a significantly lower temperature than untreated guide. Saw blades and guides that operate at a cooler temperature are expected to reduce the amount of tissue damage (thermal necrosis) and may reduce the number of post-operative complications.« less

AERODYNAMIC AND BLADING DESIGN OF MULTISTAGE AXIAL FLOW COMPRESSORS

NASA Technical Reports Server (NTRS)

Crouse, J. E.

1994-01-01

The axial-flow compressor is used for aircraft engines because it has distinct configuration and performance advantages over other compressor types. However, good potential performance is not easily obtained. The designer must be able to model the actual flows well enough to adequately predict aerodynamic performance. This computer program has been developed for computing the aerodynamic design of a multistage axial-flow compressor and, if desired, the associated blading geometry input for internal flow analysis. The aerodynamic solution gives velocity diagrams on selected streamlines of revolution at the blade row edges. The program yields aerodynamic and blading design results that can be directly used by flow and mechanical analysis codes. Two such codes are TSONIC, a blade-to-blade channel flow analysis code (COSMIC program LEW-10977), and MERIDL, a more detailed hub-to-shroud flow analysis code (COSMIC program LEW-12966). The aerodynamic and blading design program can reduce the time and effort required to obtain acceptable multistage axial-flow compressor configurations by generating good initial solutions and by being compatible with available analysis codes. The aerodynamic solution assumes steady, axisymmetric flow so that the problem is reduced to solving the two-dimensional flow field in the meridional plane. The streamline curvature method is used for the iterative aerodynamic solution at stations outside of the blade rows. If a blade design is desired, the blade elements are defined and stacked within the aerodynamic solution iteration. The blade element inlet and outlet angles are established by empirical incidence and deviation angles to the relative flow angles of the velocity diagrams. The blade element centerline is composed of two segments tangentially joined at a transition point. The local blade angle variation of each element can be specified as a fourth-degree polynomial function of path distance. Blade element thickness can also be specified with fourth-degree polynomial functions of path distance from the maximum thickness point. Input to the aerodynamic and blading design program includes the annulus profile, the overall compressor mass flow, the pressure ratio, and the rotative speed. A number of input parameters are also used to specify and control the blade row aerodynamics and geometry. The output from the aerodynamic solution has an overall blade row and compressor performance summary followed by blade element parameters for the individual blade rows. If desired, the blade coordinates in the streamwise direction for internal flow analysis codes and the coordinates on plane sections through blades for fabrication drawings may be stored and printed. The aerodynamic and blading design program for multistage axial-flow compressors is written in FORTRAN IV for batch execution and has been implemented on an IBM 360 series computer with a central memory requirement of approximately 470K of 8 bit bytes. This program was developed in 1981.

Comparison of laser anemometer measurements and theory in an annular turbine cascade with experimental accuracy determined by parameter estimation

NASA Technical Reports Server (NTRS)

Goldman, L. J.; Seasholtz, R. G.

1982-01-01

Experimental measurements of the velocity components in the blade to blade (axial tangential) plane were obtained with an axial flow turbine stator passage and were compared with calculations from three turbomachinery computer programs. The theoretical results were calculated from a quasi three dimensional inviscid code, a three dimensional inviscid code, and a three dimensional viscous code. Parameter estimation techniques and a particle dynamics calculation were used to assess the accuracy of the laser measurements, which allow a rational basis for comparison of the experimenal and theoretical results. The general agreement of the experimental data with the results from the two inviscid computer codes indicates the usefulness of these calculation procedures for turbomachinery blading. The comparison with the viscous code, while generally reasonable, was not as good as for the inviscid codes.

The construction and operation of a water tunnel in application to flow visualization studies of an oscillating airfoil

NASA Technical Reports Server (NTRS)

Olsen, J. H.; Liu, H. T.

1973-01-01

The water tunnel which was constructed at the NASA Ames Research Center is described along with the flow field adjacent to an oscillating airfoil. The design and operational procedures of the tunnel are described in detail. Hydrogen bubble and thymol blue techniques are used to visualize the flow field. Results of the flow visualizations are presented in a series of still pictures and a high speed movie. These results show that time stall is more complicated than simple shedding from the leading edge or the trailing edge, particularly at relatively low frequency oscillations comparable to those of a helicopter blade. Therefore, any successful theory for predicting the stall loads on the helicopter blades must treat an irregular separated region rather than a discrete vortex passing over each blade surface.

On the transonic aerodynamics of a compressor blade row

NASA Technical Reports Server (NTRS)

Erickson, J. C., Jr.; Lordi, J. A.; Rae, W. J.

1971-01-01

Linearized analyses have been carried out for the induced velocity and pressure fields within a compressor blade row operating in an infinite annulus at transonic Mach numbers of the flow relative to the blades. In addition, the relationship between the induced velocity and the shape of the mean blade surface has been determined. A computational scheme has been developed for evaluating the blade mean surface ordinates and surface pressure distributions. The separation of the effects of a specified blade thickness distribution from the effects of a specified distribution of the blade lift has been established. In this way, blade mean surface shapes that are necessary for the blades to be locally nonlifting have been computed and are presented for two examples of blades with biconvex parabolic arc sections of radially tapering thickness. Blade shapes that are required to achieve a zero thickness, uniform chordwise loading, constant work spanwise loading are also presented for two examples. In addition, corresponding surface pressure distributions are given. The flow relative to the blade tips has a high subsonic Mach number in the examples that have been computed. The results suggest that at near-sonic relative tip speeds the effective blade shape is dominated by the thickness distribution, with the lift distribution playing only a minor role.

Design and evaluation of low cost blades for large wind driven generating systems

NASA Technical Reports Server (NTRS)

Eggert, W. S.

1982-01-01

The development and evaluation of a low cost blade concept based on the NASA-Lewis specifications is discussed. A blade structure was designed and construction methods and materials were selected. Complete blade tooling concepts, various technical and economic analysis, and evaluations of the blade design were performed. A comprehensive fatigue test program was conducted to provide data and to verify the design. A test specimen of the spar assembly, including the root end attachment, was fabricated. This is a full-scale specimen of the root end configuration, 20 ft long. A blade design for the Mod '0' system was completed.

Rotor Broadband Noise Prediction with Comparison to Model Data

NASA Technical Reports Server (NTRS)

Brooks, Thomas F.; Burley, Casey L.

2001-01-01

This paper reports an analysis and prediction development of rotor broadband noise. The two primary components of this noise are Blade-Wake Interaction (BWI) noise, due to the blades' interaction with the turbulent wakes of the preceding blades, and "Self" noise, due to the development and shedding of turbulence within the blades' boundary layers. Emphasized in this report is the new code development for Self noise. The analysis and validation employs data from the HART program, a model BO-105 rotor wind tunnel test conducted in the German-Dutch Wind Tunnel (DNW). The BWI noise predictions are based on measured pressure response coherence functions using cross-spectral methods. The Self noise predictions are based on previously reported semiempirical modeling of Self noise obtained from isolated airfoil sections and the use of CAMRAD.Modl to define rotor performance and local blade segment flow conditions. Both BWI and Self noise from individual blade segments are Doppler shifted and summed at the observer positions. Prediction comparisons with measurements show good agreement for a range of rotor operating conditions from climb to steep descent. The broadband noise predictions, along with those of harmonic and impulsive Blade-Vortex Interaction (BVI) noise predictions, demonstrate a significant advance in predictive capability for main rotor noise.

Design of an Advanced Wood Composite Rotor and Development of Wood Composite Blade Technology

NASA Technical Reports Server (NTRS)

Stroebel, Thomas; Dechow, Curtis; Zuteck, Michael

1984-01-01

In support of a program to advance wood composite wind turbine blade technology, a design was completed for a prototype, 90-foot diameter, two-bladed, one-piece rotor, with all wood/epoxy composite structure. The rotor was sized for compatibility with a generator having a maximum power rating of 4000 kilowatts. Innovative features of the rotor include: a teetering hub to minimize the effects of gust loads, untwisted blades to promote rotor power control through stall, joining of blades to the hub structure via an adhesive bonded structural joint, and a blade structural design which was simplified relative to earlier efforts. The prototype rotor was designed to allow flexibility for configuring the rotor upwind or downwind of the tower, for evaluating various types of teeter dampers and/or elastomeric stops, and with variable delta-three angle settings of the teeter shaft axis. The prototype rotor was also designed with provisions for installing pressure tap and angle of attack instrumentation in one blade. A production version rotor cost analysis was conducted. Included in the program were efforts directed at developing advanced load take-off stud designs for subsequent evaluation testing by NASA, development of aerodynamic tip brake concepts, exploratory testing of a wood/epoxy/graphite concept, and compression testing of wood/epoxy laminate, with scarf-jointed plies.

Design optimization of axial flow hydraulic turbine runner: Part I - an improved Q3D inverse method

NASA Astrophysics Data System (ADS)

Peng, Guoyi; Cao, Shuliang; Ishizuka, Masaru; Hayama, Shinji

2002-06-01

With the aim of constructing a comprehensive design optimization procedure of axial flow hydraulic turbine, an improved quasi-three-dimensional inverse method has been proposed from the viewpoint of system and a set of rotational flow governing equations as well as a blade geometry design equation has been derived. The computation domain is firstly taken from the inlet of guide vane to the far outlet of runner blade in the inverse method and flows in different regions are solved simultaneously. So the influence of wicket gate parameters on the runner blade design can be considered and the difficulty to define the flow condition at the runner blade inlet is surmounted. As a pre-computation of initial blade design on S2m surface is newly adopted, the iteration of S1 and S2m surfaces has been reduced greatly and the convergence of inverse computation has been improved. The present model has been applied to the inverse computation of a Kaplan turbine runner. Experimental results and the direct flow analysis have proved the validation of inverse computation. Numerical investigations show that a proper enlargement of guide vane distribution diameter is advantageous to improve the performance of axial hydraulic turbine runner. Copyright

Nonlinear Control of a Reusable Rocket Engine for Life Extension

NASA Technical Reports Server (NTRS)

Lorenzo, Carl F.; Holmes, Michael S.; Ray, Asok

1998-01-01

This paper presents the conceptual development of a life-extending control system where the objective is to achieve high performance and structural durability of the plant. A life-extending controller is designed for a reusable rocket engine via damage mitigation in both the fuel (H2) and oxidizer (O2) turbines while achieving high performance for transient responses of the combustion chamber pressure and the O2/H2 mixture ratio. The design procedure makes use of a combination of linear and nonlinear controller synthesis techniques and also allows adaptation of the life-extending controller module to augment a conventional performance controller of the rocket engine. The nonlinear aspect of the design is achieved using non-linear parameter optimization of a prescribed control structure. Fatigue damage in fuel and oxidizer turbine blades is primarily caused by stress cycling during start-up, shutdown, and transient operations of a rocket engine. Fatigue damage in the turbine blades is one of the most serious causes for engine failure.

Some issues on modeling atmospheric turbulence experienced by helicopter rotor blades

NASA Technical Reports Server (NTRS)

Costello, Mark; Gaonkar, G. H.; Prasad, J. V. R.; Schrage, D. P.

1992-01-01

The atmospheric turbulence velocities seen by nonrotating aircraft components and rotating blades can be substantially different. The differences are due to the spatial motion of the rotor blades, which move fore and aft through the gust waves. Body-fixed atmospheric turbulence refers to the actual atmospheric turbulence experienced by a point fixed on a nonrotating aircraft component such as the aircraft's center of gravity or the rotor hub, while blade-fixed atmospheric turbulence refers to the atmospheric turbulence experienced by an element of the rotating rotor blade. An example is presented, which, though overly simplified, shows important differences between blade- and body-fixed rotorcraft atmospheric turbulence models. All of the information necessary to develop the dynamic equations describing the atmospheric turbulence velocity field experienced by an aircraft is contained in the atmospheric turbulence velocity correlation matrix. It is for this reason that a generalized formulation of the correlation matrix describing atmospheric turbulence that a rotating blade encounters is developed. From this correlation matrix, earlier treated cases restricted to a rotor flying straight and level directly into the mean wind can be recovered as special cases.

Piezoelectric Vibration Damping Study for Rotating Composite Fan Blades

NASA Technical Reports Server (NTRS)

Min, James B.; Duffy, Kirsten P.; Choi, Benjamin B.; Provenza, Andrew J.; Kray, Nicholas

2012-01-01

Resonant vibrations of aircraft engine blades cause blade fatigue problems in engines, which can lead to thicker and aerodynamically lower performing blade designs, increasing engine weight, fuel burn, and maintenance costs. In order to mitigate undesirable blade vibration levels, active piezoelectric vibration control has been investigated, potentially enabling thinner blade designs for higher performing blades and minimizing blade fatigue problems. While the piezoelectric damping idea has been investigated by other researchers over the years, very little study has been done including rotational effects. The present study attempts to fill this void. The particular objectives of this study were: (a) to develop and analyze a multiphysics piezoelectric finite element composite blade model for harmonic forced vibration response analysis coupled with a tuned RLC circuit for rotating engine blade conditions, (b) to validate a numerical model with experimental test data, and (c) to achieve a cost-effective numerical modeling capability which enables simulation of rotating blades within the NASA Glenn Research Center (GRC) Dynamic Spin Rig Facility. A numerical and experimental study for rotating piezoelectric composite subscale fan blades was performed. It was also proved that the proposed numerical method is feasible and effective when applied to the rotating blade base excitation model. The experimental test and multiphysics finite element modeling technique described in this paper show that piezoelectric vibration damping can significantly reduce vibrations of aircraft engine composite fan blades.

An Assessment of the Icing Blade and the SEA Multi-Element Sensor for Liquid Water Content Calibration of the NASA GRC Icing Research Tunnel

NASA Technical Reports Server (NTRS)

Steen, Laura E.; Ide, Robert F.; Van Zante, Judith Foss

2017-01-01

The Icing Research Tunnel at NASA Glenn has recently switched to from using the Icing Blade to using the SEA Multi-Element Sensor (also known as the multi-wire) for its calibration of cloud liquid water content. In order to perform this transition, tests were completed to compare the Multi-Element Sensor to the Icing Blade, particularly with respect to liquid water content, airspeed, and drop size. The two instruments were found to compare well for the majority of Appendix C conditions. However, it was discovered that the Icing Blade under-measures when the conditions approach the Ludlam Limit. This paper also describes data processing procedures for the Multi-Element Sensor in the IRT, including collection efficiency corrections, mounting underneath a splitter plate, and correcting for a jump in the compensation wire power. Further data is presented to describe the repeatability of the IRT with the Multi-Element sensor, health-monitoring checks for the instrument, and a sensing-element configuration comparison.

A PFC3D-based numerical simulation of cutting load for lunar rock simulant and experimental validation

NASA Astrophysics Data System (ADS)

Li, Peng; Jiang, Shengyuan; Tang, Dewei; Xu, Bo

2017-05-01

For sake of striking a balance between the need of drilling efficiency and the constrains of power budget on the moon, the penetrations per revolution of drill bit are generally limited in the range around 0.1 mm, and besides the geometric angle of the cutting blade need to be well designed. This paper introduces a simulation approach based on PFC3D (particle flow code 3 dimensions) for analyzing the cutting load feature on lunar rock simulant, which is derived from different geometric-angle blades with a small cutting depth. The mean values of the cutting force of five blades in the survey region (four on the boundary points and one on the center point) are selected as the macroscopic responses of model. The method of experimental design which includes Plackett-Burman (PB) design and central composite design (CCD) method is adopted in the matching procedure of microparameters in PFC model. Using the optimization method of enumeration, the optimum set of microparameters is acquired. Then, the experimental validation is implemented by using other twenty-five blades with different geometric angles, and the results from both simulations and laboratory tests give fair agreements. Additionally, the rock breaking process cut by different blades are quantified from simulation analysis. This research provides the theoretical support for the refinement of the rock cutting load prediction and the geometric design of cutting blade on the drill bit.

Study of noise sources in a subsonic fan using measured blade pressures and acoustic theory

NASA Technical Reports Server (NTRS)

Hanson, D. B.

1975-01-01

Sources of noise in a 1.4 m (4.6 ft) diameter subsonic tip speed propulsive fan running statically outdoors are studied using a combination of techniques. Signals measured with pressure transducers on a rotor blade are plotted in a format showing the space-time history of inlet distortion. Study of these plots visually and with statistical correlation analysis confirms that the inlet flow contains long, thin eddies of turbulence. Turbulence generated in the boundary layer of the shroud upstream of the rotor tips was not found to be an important noise source. Fan noise is diagnosed by computing narrowband spectra of rotor and stator sound power and comparing these with measured sound power spectra. Rotor noise is computed from spectra of the measured blade pressures and stator noise is computed using the author's stator noise theory. It is concluded that the rotor and stator sources contribute about equally at frequencies in the vicinity of the first three harmonics of blade passing frequency. At higher frequencies, the stator contribution diminishes rapidly and the rotor/inlet turbulence mechanism dominates. Two parametric studies are performed by using the rotor noise calculation procedure which was correlated with test. In the first study, the effects on noise spectrum and directivity are calculated for changes in turbulence properties, rotational Mach number, number of blades, and stagger angle. In the second study the influences of design tip speed and blade number on noise are evaluated.

Numerical and experimental evidence of the inter-blade cavitation vortex development at deep part load operation of a Francis turbine

NASA Astrophysics Data System (ADS)

Yamamoto, K.; Müller, A.; Favrel, A.; Landry, C.; Avellan, F.

2016-11-01

Francis turbines are subject to various types of the cavitation flow depending on the operating conditions. In order to compensate for the stochastic nature of renewable energy sources, it is more and more required to extend the operating range of the generating units, from deep part load to full load conditions. In the deep part load condition, the formation of cavitation vortices in the turbine blade to blade channels called inter-blade cavitation vortex is often observed. The understanding of the dynamic characteristics of these inter-blade vortices and their formation mechanisms is of key importance in an effort of developing reliable flow simulation tools. This paper reports the numerical and experimental investigations carried out in order to establish the vortex characteristics, especially the inception and the development of the vortex structure. The unsteady RANS simulation for the multiphase flow is performed with the SST- SAS turbulence model by using the commercial flow solver ANSYS CFX. The simulation results in terms of the vortex structure and the cavitation volume are evaluated by comparing them to the flow visualizations of the blade channel acquired through a specially instrumented guide vane as well as from the downstream of the runner across the draft tube cone. The inter-blade cavitation vortex is successfully captured by the simulation and both numerical and experimental results evidence that the inter-blade vortices are attached to the runner hub.

Penetrating and Intrastromal Corneal Arcuate Incisions in Rabbit and Human Cadaver Eyes: Manual Diamond Blade and Femtosecond Laser-Created Incisions.

PubMed

Gray, Brad; Binder, Perry S; Huang, Ling C; Hill, Jim; Salvador-Silva, Mercedes; Gwon, Arlene

2016-07-01

To compare morphologic differences between freehand diamond or femtosecond laser-assisted penetrating and intrastromal arcuate incisions. Freehand diamond blade, corneal arcuate incisions (180° apart, 60° arc lengths) and 150 kHz femtosecond laser (80% scheimpflug pachymetry depth corneal thickness) arcuate incisions were performed in rabbits. Intrastromal arcuate incisions (100 μm above Descemet's membrane, 100 μm below epithelium) were performed in rabbit corneas (energy 1.2 μJ, spot line separation 3 × 3 μm, 90° side cut angle). Eyes were examined by slit lamp and light microscopy up to 47 days post-procedure. Freehand diamond blade penetrating incisions, and femtosecond laser penetrating and intrastromal arcuate incisions (energy 1.8 μJ, spot line separation 2 × 2 μm) were performed in cadaver eyes. Optical coherence tomography was performed immediately after surgery and the corneas were fixed for light scanning and transmission electron microscopy. The rabbit model showed anterior stromal inflammation with epithelial hyperplasia in penetrating blade and laser penetrating wounds. The laser intrastromal and penetrating incisions showed localized constriction of the stromal layers of the cornea near the wound. In cadaver eyes, penetrating wound morphology was similar between blade and laser whereas intrastromal wounds did not affect the cornea above or below incisions. Penetrating femtosecond laser arcuate incisions have more predictable and controlled outcomes shown by less post-operative scarring than incisions performed with a diamond blade. Intrastromal incisions do not affect uncut corneal layers as demonstrated by histopathology. The femtosecond laser has significant advantages in its ability to make intrastromal incisions which are not achievable by traditional freehand or mechanical diamond blades.

Symbolic generation of elastic rotor blade equations using a FORTRAN processor and numerical study on dynamic inflow effects on the stability of helicopter rotors

NASA Technical Reports Server (NTRS)

Reddy, T. S. R.

1986-01-01

The process of performing an automated stability analysis for an elastic-bladed helicopter rotor is discussed. A symbolic manipulation program, written in FORTRAN, is used to aid in the derivation of the governing equations of motion for the rotor. The blades undergo coupled bending and torsional deformations. Two-dimensional quasi-steady aerodynamics below stall are used. Although reversed flow effects are neglected, unsteady effects, modeled as dynamic inflow are included. Using a Lagrangian approach, the governing equations are derived in generalized coordinates using the symbolic program. The program generates the steady and perturbed equations and writes into subroutines to be called by numerical routines. The symbolic program can operate on both expressions and matrices. For the case of hovering flight, the blade and dynamic inflow equations are converted to equations in a multiblade coordinate system by rearranging the coefficients of the equations. For the case of forward flight, the multiblade equations are obtained through the symbolic program. The final multiblade equations are capable of accommodating any number of elastic blade modes. The computer implementation of this procedure consists of three stages: (1) the symbolic derivation of equations; (2) the coding of the equations into subroutines; and (3) the numerical study after identifying mass, damping, and stiffness coefficients. Damping results are presented in hover and in forward flight with and without dynamic inflow effects for various rotor blade models, including rigid blade lag-flap, elastic flap-lag, flap-lag-torsion, and quasi-static torsion. Results from dynamic inflow effects which are obtained from a lift deficiency function for a quasi-static inflow model in hover are also presented.

Operation of Darrieus turbines in constant circulation framework

NASA Astrophysics Data System (ADS)

Gorle, J. M. R.; Chatellier, L.; Pons, F.; Ba, M.

2017-07-01

Analytical and computational studies of flow across a low-speed marine turbine of Darrieus type with pitching blades have been carried out for flowfield and performance evaluation. The objective of this study is to develop efficient blade pitching laws to arrest or control the vortex shedding from the blades during turbine's operation. This is achieved by imparting an arbitrary constant amount of circulation to the blades, where Kelvin's theorem is respected. This paper presents the extension of the application of conformal mapping to produce the time-dependent flow over a rotating turbine blade in order to develop a quantified relationship between the blade's orientation with respect to the rotor's tangent and its rotational motion. The flow development is based on the analytical treatment given to potential flow formulation through Laurent series decomposition, where the Kutta condition is satisfied. The pitch control law and the analytical modeling of the hydrodynamic forces acting on the blade are derived based on Kelvin's theorem for the conservation of circulation. The application of this pitch control law in the real flow conditions is however limited due to viscous losses and rotational effects. Therefore, a 2D computational fluid dynamics (CFD) study with the shear stress transport (SST) k -ω turbulence model has been performed to examine the flow across a 4-bladed turbine model. While validating the analytical work, the numerical investigation reveals the applicability and limitations of circulation-controlled blade pitching laws in real flow conditions. In particular, a reference equivalent angle of attack is defined, which must be contained in a tight range in order to effectively prevent vortex shedding at a given tip-speed ratio.

A three-dimensional structured/unstructured hybrid Navier-Stokes method for turbine blade rows

NASA Technical Reports Server (NTRS)

Tsung, F.-L.; Loellbach, J.; Kwon, O.; Hah, C.

1994-01-01

A three-dimensional viscous structured/unstructured hybrid scheme has been developed for numerical computation of high Reynolds number turbomachinery flows. The procedure allows an efficient structured solver to be employed in the densely clustered, high aspect-ratio grid around the viscous regions near solid surfaces, while employing an unstructured solver elsewhere in the flow domain to add flexibility in mesh generation. Test results for an inviscid flow over an external transonic wing and a Navier-Stokes flow for an internal annular cascade are presented.

Cyclogiro windmill

DOEpatents

Brulle, R.V.

1981-09-03

A cyclogiro windmill has a rotor provided with blades shaped in the configuration of symmetrical airfoils and actuators to pivot the blades about axes parallel to the axis of rotation for the rotor. The actuator for each blade constantly changes the rock angle for the blade, that is its angle with respect to a reference on the rotor, and this modulation is such that the blade in making a revolution around the axis of rotation for the rotor undergoes an interval of static operation wherein its angle of attack is for the most part constant and less than the static stall angle, a short interval where the blade flips to position in which its opposite surface is presented toward the free wind, a short interval of dynamic operation wherein the angle of attack exceeds the static stal angle, another interval of static operation at an angle of attack of essentially the same magnitude as before, another interval of blade flip, and another interval of dynamic operation. During the intervals of dynamic operation, the blades experience a significant increase in lift force without a corresponding increase in drag, so that a high lift-to-drag ratio develops. The blades during dynamic operation further develop strong vortices which are directed outwardly at the sides of the windmill stream tube, and this increases the width of the stream tube, causing a greater mass of air to flow through the rotor. The short intervals of operation under dynamic conditions enable the blades to extract more energy from the free wind than would be possible if the blade operated solely under static conditions, and this in turn renders the windmill more useful in moderate velocity winds as well as high velocity winds.

Cyclogiro windmill

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brulle, R.V.

1981-09-03

A cyclogiro windmill has a rotor provided with blades shaped in the configuration of symmetrical airfoils and actuators to pivot the blades about axes parallel to the axis of rotation for the rotor. The actuator for each blade constantly changes the rock angle for the blade, that is its angle with respect to a reference on the rotor, and this modulation is such that the blade in making a revolution around the axis of rotation for the rotor undergoes an interval of static operation wherein its angle of attack is for the most part constant and less than the staticmore » stall angle, a short interval where the blade flips to position in which its opposite surface is presented toward the free wind, a short interval of dynamic operation wherein the angle of attack exceeds the static stal angle, another interval of static operation at an angle of attack of essentially the same magnitude as before, another interval of blade flip, and another interval of dynamic operation. During the intervals of dynamic operation, the blades experience a significant increase in lift force without a corresponding increase in drag, so that a high lift-to-drag ratio develops. The blades during dynamic operation further develop strong vortices which are directed outwardly at the sides of the windmill stream tube, and this increases the width of the stream tube, causing a greater mass of air to flow through the rotor. The short intervals of operation under dynamic conditions enable the blades to extract more energy from the free wind than would be possible if the blade operated solely under static conditions, and this in turn renders the windmill more useful in moderate velocity winds as well as high velocity winds.« less

The development of furrower model blade to paddlewheel aerator for improving aeration efficiency

NASA Astrophysics Data System (ADS)

Bahri, Samsul; Praeko Agus Setiawan, Radite; Hermawan, Wawan; Zairin Junior, Muhammad

2018-05-01

The successful of intensive aquaculture is strongly influenced by the ability of the farmers to overcome the deterioration of water quality. The problem is low dissolved oxygen through aeration process. The aerator device which widely used in pond farming is paddle wheel aerator because it is the best aerator in aeration mechanism and usable driven power. However, this aerator still has a low performance of aeration, so that the cost of aerator operational for aquaculture is still high. Up to now, the effort to improve the performance of aeration was made by two-dimensional blade design. Obviously, it does not provide the optimum result due to the power requirements for aeration is directly proportional to the increase of aeration rate. The aim of this research is to develop three-dimensional model furrowed blades. Design of Furrower model blades was 1.6 cm diameter hole, 45º of vertical angle blade position and 30º of the horizontal position. The optimum performance furrowed model blades operated on the submerged blade 9 cm with 567.54 Watt of electrical power consumption and 4.322 m3 of splash coverage volume. The standard efficiency aeration is 2.72 kg O2 kWh-1. The furrowed model blades can improve the aeration efficiency of paddlewheel aerator.

Low noise propeller design using numerical analysis

NASA Astrophysics Data System (ADS)

Humpert, Bryce

The purpose of this study is to explore methods for reducing aircraft propeller noise with minimal losses in performance. Using numerical analysis, a standard two blade propeller configuration was taken from experiments conducted by Patrick, Finn, and Stich, and implemented into the numerical code XROTOR. The blade design modifications that were investigated to achieve the proposed goals include: increasing the number of blades, adjusting the chord length, beta distribution, radius of the blade, airfoil shape, and operating RPM. In order to determine the optimal blade design, a baseline case is first developed and the parameters listed earlier are then varied to create a new propeller design that reduces the sound pressure level (SPL) while maintaining performance levels within a predetermined range of the original specifications. From the analysis, the most significant improvements observed in lowering the acoustic signature are dominated by operating rpm and blade radius. A three-, four-, and five-blade configuration was developed that reduced the SPL generated by the propeller during cruise flight conditions. The optimum configuration that produced the greatest SPL reduction was the five-blade configuration. The resulting sound pressure level was reduced from the original 77 dB at 1000' ft above ground level (AGL), to 54 dB at 1000' AGL while remaining within 1.4% of the original thrust and efficiency.

Aeroelasticity and structural optimization of composite helicopter rotor blades with swept tips

NASA Technical Reports Server (NTRS)

Yuan, K. A.; Friedmann, P. P.

1995-01-01

This report describes the development of an aeroelastic analysis capability for composite helicopter rotor blades with straight and swept tips, and its application to the simulation of helicopter vibration reduction through structural optimization. A new aeroelastic model is developed in this study which is suitable for composite rotor blades with swept tips in hover and in forward flight. The hingeless blade is modeled by beam type finite elements. A single finite element is used to model the swept tip. Arbitrary cross-sectional shape, generally anisotropic material behavior, transverse shears and out-of-plane warping are included in the blade model. The nonlinear equations of motion, derived using Hamilton's principle, are based on a moderate deflection theory. Composite blade cross-sectbnal properties are calculated by a separate linear, two-dimensional cross section analysis. The aerodynamic loads are obtained from quasi-steady, incompressible aerodynamics, based on an implicit formulation. The trim and steady state blade aeroelastic response are solved in a fully coupled manner. In forward flight, where the blade equations of motion are periodic, the coupled trim-aeroelastic response solution is obtained from the harmonic balance method. Subsequently, the periodic system is linearized about the steady state response, and its stability is determined from Floquet theory.

Development of advanced lightweight containment systems

NASA Technical Reports Server (NTRS)

Stotler, C.

1981-01-01

Parametric type data were obtained on advanced lightweight containment systems. These data were used to generate design methods and procedures necessary for the successful development of such systems. The methods were then demonstrated through the design of a lightweight containment system for a CF6 size engine. The containment concept evaluated consisted basically of a lightweight structural sandwich shell wrapped with dry Kevlar cloth. The initial testing was directed towards the determination of the amount of Kevlar required to result in threshold containment for a specific set of test conditions. A relationship was then developed between the thickness required and the energy of the released blade so that the data could be used to design for conditions other than those tested.

Examination of the collision force method for analyzing the responses of simple containment/deflection structures to impact by one engine rotor blade fragment

NASA Technical Reports Server (NTRS)

Zirin, R. M.; Witmer, E. A.

1972-01-01

An approximate collision analysis, termed the collision-force method, was developed for studying impact-interaction of an engine rotor blade fragment with an initially circular containment ring. This collision analysis utilizes basic mass, material property, geometry, and pre-impact velocity information for the fragment, together with any one of three postulated patterns of blade deformation behavior: (1) the elastic straight blade model, (2) the elastic-plastic straight shortening blade model, and (3) the elastic-plastic curling blade model. The collision-induced forces are used to predict the resulting motions of both the blade fragment and the containment ring. Containment ring transient responses are predicted by a finite element computer code which accommodates the large deformation, elastic-plastic planar deformation behavior of simple structures such as beams and/or rings. The effects of varying the values of certain parameters in each blade-behavior model were studied. Comparisons of predictions with experimental data indicate that of the three postulated blade-behavior models, the elastic-plastic curling blade model appears to be the most plausible and satisfactory for predicting the impact-induced motions of a ductile engine rotor blade and a containment ring against which the blade impacts.

Smart helicopter rotor with active blade tips

NASA Astrophysics Data System (ADS)

Bernhard, Andreas Paul Friedrich

2000-10-01

The smart active blade tip (SABT) rotor is an on-blade rotor vibration reduction system, incorporating active blade tips that can be independently pitched with respect to the main blade. The active blade tip rotor development included an experimental test program culminating in a Mach scale hover test, and a parallel development of a coupled, elastic actuator and rotor blade analysis for preliminary design studies and hover performance prediction. The experimental testing focussed on a small scale rotor on a bearingless Bell-412 hub. The fabricated Mach-scale active-tip rotor has a diameter of 1.524 m, a blade chord of 76.2 mm and incorporated a 10% span active tip. The nominal operating speed is 2000 rpm, giving a tip Mach number of 0.47. The blade tips are driven by a novel piezo-induced bending-torsion coupled actuator beam, located spanwise in the hollow mid-cell of the main rotor blade. In hover at 2000 rpm, at 2 deg collective, and for an actuation of 125 Vrms, the measured blade tip deflection at the first four rotor harmonics is between +/-1.7 and +/-2.8 deg, increasing to +/-5.3 deg at 5/rev with resonant amplification. The corresponding oscillatory amplitude of the rotor thrust coefficient is between 0.7 · 10-3 and 1.3 · 10-1 at the first four rotor harmonics, increasing to 2.1 · 10-3 at 5/rev. In general, the experimental blade tip frequency response and corresponding rotor thrust response are well captured by the analysis. The flexbeam root flap bending moment is predicted in trend, but is significantly over-estimated. The blade tips did not deflect as expected at high collective settings, because of the blade tip shaft locking up in the bearing. This is caused by the high flap bending moment on the blade tip shaft. Redesign of the blade tip shaft assembly and bearing support is identified as the primary design improvement for future research. The active blade tip rotor was also used as a testbed for the evaluation of an adaptive neural-network based control algorithm. Effective background vibration reduction of an intentional 1/rev hover imbalance was demonstrated. The control algorithm also showed the capability to generate desired multi-frequency control loads on the hub, based on artificial signal injection into the vibration measurement. The research program demonstrates the technical feasibility of the active blade tip concept for vibration reduction and warrants further investigation in terms of closed loop forward flight tests in the windtunnel and full scale design studies.

Blade pressure measurements

NASA Astrophysics Data System (ADS)

Chivers, J. W. H.

Three measurement techniques which enable rotating pressures to be measured during the normal operation of a gas turbine or a component test rig are described. The first technique was developed specifically to provide steady and transient blade surface pressure data to aid both fan flutter research and general fan performance development. This technique involves the insertion of miniature high frequency response pressure transducers into the fan blades of a large civil gas turbine. The other two techniques were developed to measure steady rotating pressures inside and on the surface of engine or rig turbine blades and also rotating pressures in cooling feed systems. These two low frequency response systems are known as the "pressure pineapple' (a name which resulted from the shape of the original prototype) and the rotating scanivalve.

Tungsten fiber reinforced FeCralY: A first generation composite turbine blade material

NASA Technical Reports Server (NTRS)

Petrasek, D. W.; Winsa, E. A.; Westfall, L. J.; Signorelli, R. A.

1979-01-01

Tungsten-fiber/FeCrAlY (W/FeCrAlY) was identified as a promising aircraft engine, first generation, turbine blade composite material. Based on available data, W/FeCrAlY should have the stress-rupture, creep, tensile, fatigue, and impact strengths required for turbine blades operating from 1250 to 1370 K. It should also have adequate oxidation, hot corrosion, and thermal cycling damage resistance as well as high thermal conductivity. Concepts for potentially low cost blade fabrication were developed. These concepts were used to design a first stage JT9D convection cooled turbine blade having a calculated 50 K use-temperature advantage over the directionally solidified superalloy blade.

Vibration and loads in hingeless rotors. Volume 1: Theoretical analyses

NASA Technical Reports Server (NTRS)

Watts, G. A.; London, R. J.

1972-01-01

Analytic methods are developed for calculating blade loads and shaft-transmitted vibratory forces in stiff bladed hingeless rotors operating at advance ratios from mu = .3 to mu = 2.0. Calculated shaft harmonic moments compared well with experimental values when the blade first flap frequency was in the region of two-per-revolution harmonic excitation. Calculated blade bending moment azimuthal distributions due to changes in cyclic pitch agreed well with experiment at radial stations near the blade root at values of the ratio of first flap frequency to rotor rotation rate from 1.5 to 5.0. At stations near the blade tip good agreement was only obtained at the higher values of frequency ratio.

Enhancement to Non-Contacting Stress Measurement of Blade Vibration Frequency

NASA Technical Reports Server (NTRS)

Platt, Michael; Jagodnik, John

2011-01-01

A system for turbo machinery blade vibration has been developed that combines time-of-arrival sensors for blade vibration amplitude measurement and radar sensors for vibration frequency and mode identification. The enabling technology for this continuous blade monitoring system is the radar sensor, which provides a continuous time series of blade displacement over a portion of a revolution. This allows the data reduction algorithms to directly calculate the blade vibration frequency and to correctly identify the active modes of vibration. The work in this project represents a significant enhancement in the mode identification and stress calculation accuracy in non-contacting stress measurement system (NSMS) technology when compared to time-of-arrival measurements alone.

Multi-objective optimization of piezoelectric circuitry network for mode delocalization and suppression of bladed disk

NASA Astrophysics Data System (ADS)

Yoo, David; Tang, J.

2017-04-01

Since weakly-coupled bladed disks are highly sensitive to the presence of uncertainties, they can easily undergo vibration localization. When vibration localization occurs, vibration modes of bladed disk become dramatically different from those under the perfectly periodic condition, and the dynamic response under engine-order excitation is drastically amplified. In previous studies, it is investigated that amplified vibration response can be suppressed by connecting piezoelectric circuitry into individual blades to induce the damped absorber effect, and localized vibration modes can be alleviated by integrating piezoelectric circuitry network. Delocalization of vibration modes and vibration suppression of bladed disk, however, require different optimal set of circuit parameters. In this research, multi-objective optimization approach is developed to enable finding the best circuit parameters, simultaneously achieving both objectives. In this way, the robustness and reliability in bladed disk can be ensured. Gradient-based optimizations are individually developed for mode delocalization and vibration suppression, which are then integrated into multi-objective optimization framework.

Diffusion bonded boron/aluminum spar-shell fan blade

NASA Technical Reports Server (NTRS)

Carlson, C. E. K.; Cutler, J. L.; Fisher, W. J.; Memmott, J. V. W.

1980-01-01

Design and process development tasks intended to demonstrate composite blade application in large high by-pass ratio turbofan engines are described. Studies on a 3.0 aspect radio space and shell construction fan blade indicate a potential weight savings for a first stage fan rotor of 39% when a hollow titanium spar is employed. An alternate design which featured substantial blade internal volume filled with titanium honeycomb inserts achieved a 14% potential weight savings over the B/M rotor system. This second configuration requires a smaller development effort and entails less risk to translate a design into a successful product. The feasibility of metal joining large subsonic spar and shell fan blades was demonstrated. Initial aluminum alloy screening indicates a distinct preference for AA6061 aluminum alloy for use as a joint material. The simulated airfoil pressings established the necessity of rigid air surfaces when joining materials of different compressive rigidities. The two aluminum alloy matrix choices both were successfully formed into blade shells.

Genetic fuzzy system for online structural health monitoring of composite helicopter rotor blades

NASA Astrophysics Data System (ADS)

Pawar, Prashant M.; Ganguli, Ranjan

2007-07-01

A structural health monitoring (SHM) methodology is developed for composite rotor blades. An aeroelastic analysis of composite rotor blades based on the finite element method in space and time and with implanted matrix cracking and debonding/delamination damage is used to obtain measurable system parameters such as blade response, loads and strains. A rotor blade with a two-cell airfoil section and [0/±45/90]s family of laminates is used for numerical simulations. The model based measurements are contaminated with noise to simulate real data. Genetic fuzzy systems (GFS) are developed for global online damage detection using displacement and force-based measurement deviations between damaged and undamaged conditions and for local online damage detection using strains. It is observed that the success rate of the GFS depends on number of measurements, type of measurements and training and testing noise level. The GFS work quite well with noisy data and is recommended for online SHM of composite helicopter rotor blades.

Dynamic response of active twist rotor blades

NASA Astrophysics Data System (ADS)

Cesnik, Carlos E. S.; Shin, Sang Joon; Wilbur, Matthew L.

2001-02-01

Dynamic characteristics of active twist rotor (ATR) blades are investigated analytically and experimentally in this paper. The ATR system is intended for vibration and potentially for noise reductions in helicopters through individual blade control. An aeroelastic model is developed to identify frequency response characteristics of the ATR blade with integral, generally anisotropic, strain actuators embedded in its composite construction. An ATR prototype blade was designed and manufactured to experimentally study the vibration reduction capabilities of such systems. Several bench and hover tests were conducted and those results are presented and discussed here. Selected results on sensitivity of the ATR system to collective setting (i.e. blade loading), blade rpm (i.e. centrifugal force and blade station velocity), and media density (i.e. altitude) are presented. They indicated that the twist actuation authority of the ATR blade is independent of the collective setting up to approximately 10P, and dependent on rotational speed and altitude near the torsional resonance frequency due to its dependency on the aerodynamic damping. The proposed model captures very well the physics and sensitivities to selected test parameters of the ATR system. The numerical result of the blade torsional loads show an average error of 20% in magnitude and virtually no difference in phase for the blade frequency response. Overall, the active blade model is in very good agreement with the experiments and can be used to analyze and design future active helicopter blade systems.

Fatigue analysis and testing of wind turbine blades

NASA Astrophysics Data System (ADS)

Greaves, Peter Robert

This thesis focuses on fatigue analysis and testing of large, multi MW wind turbine blades. The blades are one of the most expensive components of a wind turbine, and their mass has cost implications for the hub, nacelle, tower and foundations of the turbine so it is important that they are not unnecessarily strong. Fatigue is often an important design driver, but fatigue of composites is poorly understood and so large safety factors are often applied to the loads. This has implications for the weight of the blade. Full scale fatigue testing of blades is required by the design standards, and provides manufacturers with confidence that the blade will be able to survive its service life. This testing is usually performed by resonating the blade in the flapwise and edgewise directions separately, but in service these two loads occur at the same time.. A fatigue testing method developed at Narec (the National Renewable Energy Centre) in the UK in which the flapwise and edgewise directions are excited simultaneously has been evaluated by comparing the Palmgren-Miner damage sum around the blade cross section after testing with the damage distribution caused by the service life. A method to obtain the resonant test configuration that will result in the optimum mode shapes for the flapwise and edgewise directions was then developed, and simulation software was designed to allow the blade test to be simulated so that realistic comparisons between the damage distributions after different test types could be obtained. During the course of this work the shortcomings with conventional fatigue analysis methods became apparent, and a novel method of fatigue analysis based on multi-continuum theory and the kinetic theory of fracture was developed. This method was benchmarked using physical test data from the OPTIDAT database and was applied to the analysis of a complete blade. A full scale fatigue test method based on this new analysis approach is also discussed..

Integrated approach for stress based lifing of aero gas turbine blades

NASA Astrophysics Data System (ADS)

Abu, Abdullahi Obonyegba

In order to analyse the turbine blade life, the damage due to the combined thermal and mechanical loads should be adequately accounted for. This is more challenging when detailed component geometry is limited. Therefore, a compromise between the level of geometric detail and the complexity of the lifing method to be implemented would be necessary. This research focuses on how the life assessment of aero engine turbine blades can be done, considering the balance between available design inputs and adequate level of fidelity. Accordingly, the thesis contributes to developing a generic turbine blade lifing method that is based on the engine thermodynamic cycle; as well as integrating critical design/technological factors and operational parameters that influence the aero engine blade life. To this end, thermo-mechanical fatigue was identified as the critical damage phenomenon driving the life of the turbine blade.. The developed approach integrates software tools and numerical models created using the minimum design information typically available at the early design stages. Using finite element analysis of an idealised blade geometry, the approach captures relevant impacts of thermal gradients and thermal stresses that contribute to the thermo-mechanical fatigue damage on the gas turbine blade. The blade life is evaluated using the Neu/Sehitoglu thermo-mechanical fatigue model that considers damage accumulation due to fatigue, oxidation, and creep. The leading edge is examined as a critical part of the blade to estimate the damage severity for different design factors and operational parameters. The outputs of the research can be used to better understand how the environment and the operating conditions of the aircraft affect the blade life consumption and therefore what is the impact on the maintenance cost and the availability of the propulsion system. This research also finds that the environmental (oxidation) effect drives the blade life and the blade coolant side was the critical location. Furthermore, a parametric and sensitivity study of the Neu/Sehitoglu model parameters suggests that in addition to four previously reported parameters, the sensitivity of the phasing to oxidation damage would be critical to overall blade life..

The influence of dynamic inflow and torsional flexibility on rotor damping in forward flight from symbolically generated equations

NASA Technical Reports Server (NTRS)

Reddy, T. S. R.; Warmbrodt, W.

1985-01-01

The combined effects of blade torsion and dynamic inflow on the aeroelastic stability of an elastic rotor blade in forward flight are studied. The governing sets of equations of motion (fully nonlinear, linearized, and multiblade equations) used in this study are derived symbolically using a program written in FORTRAN. Stability results are presented for different structural models with and without dynamic inflow. A combination of symbolic and numerical programs at the proper stage in the derivation process makes the obtainment of final stability results an efficient and straightforward procedure.

Acute and subacute effects of the ultrasonic blade and electrosurgery on nerve physiology.

PubMed

Chen, Chaoyang; Kallakuri, Srinivasu; Cavanaugh, John M; Broughton, Duan; Clymer, Jeffrey W

2015-01-01

Ultrasonic blades have been shown to cause less acute electrophysiological damage when applied near nerves than monopolar electrosurgery (ES). This study was performed to determine whether the acute nerve damage observed for ES, as well as the relative lack of damage observed for ultrasonic dissection, extends through a subacute timeframe. Muscle incisions were made in rat with the Harmonic(®) Blade (HB) and ES at a distance of 2 mm from the sciatic nerve. Sham surgery was also performed which consisted of similar exposure of the sciatic nerve without use of an energized device. Electrophysiological function was assessed acutely over a 3-h period, and subacutely after a 7-day survival, by monitoring the sciatic nerve compound action potential (CAP), conduction velocity (CV), von Frey hair (VFH) stimulation force, leukocyte infiltration, and impaired axonal transport via β-amyloid precursor protein (β-APP) immunocytochemistry. During the acute period, ES produced significantly lower CAP and CV, and higher levels of leukocytes and β-APP than sham, whereas the ultrasonic blade was not significantly different from sham, and had significantly lower VFH force than ES. After the subacute survival, ES continued to display significantly lower CAP and CV, and higher levels of leukocytes and β-APP than sham, whereas ultrasonic blade had higher CAP and CV than sham, and lower VFH than ES. This study confirms that incisions made with an ultrasonic blade cause less acute nerve damage than monopolar ES, and are comparable to sham surgery at a distance of 2 mm from the sciatic nerve. The negative effects of electrosurgery extend through at least a 7-day survival period, whereas subacute recovery after application of the ultrasonic blade was comparable to that of sham surgery. For surgical procedures in the vicinity of vital nerves, use of the ultrasonic blade represents a lower risk than ES for both acute and subacute neural trauma.

TX-100 manufacturing final project report.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ashwill, Thomas D.; Berry, Derek S.

This report details the work completed under the TX-100 blade manufacturing portion of the Carbon-Hybrid Blade Developments: Standard and Twist-Coupled Prototype project. The TX-100 blade is a 9 meter prototype blade designed with bend-twist coupling to augment the mitigation of peak loads during normal turbine operation. This structural coupling was achieved by locating off axis carbon fiber in the outboard portion of the blade skins. The report will present the tooling selection, blade production, blade instrumentation, blade shipping and adapter plate design and fabrication. The baseline blade used for this project was the ERS-100 (Revision D) wind turbine blade. Themore » molds used for the production of the TX-100 were originally built for the production of the CX-100 blade. The same high pressure and low pressure skin molds were used to manufacture the TX-100 skins. In order to compensate for the difference in skin thickness between the CX-100 and the TX-100, however, a new TX-100 shear web plug and mold were required. Both the blade assembly fixture and the root stud insertion fixture used for the CX-100 blades could be utilized for the TX-100 blades. A production run of seven TX-100 prototype blades was undertaken at TPI Composites during the month of October, 2004. Of those seven blades, four were instrumented with strain gauges before final assembly. After production at the TPI Composites facility in Rhode Island, the blades were shipped to various test sites: two blades to the National Wind Technology Center at the National Renewable Energy Laboratory in Boulder, Colorado, two blades to Sandia National Laboratory in Albuquerque, New Mexico and three blades to the United States Department of Agriculture turbine field test facility in Bushland, Texas. An adapter plate was designed to allow the TX-100 blades to be installed on existing Micon 65/13M turbines at the USDA site. The conclusion of this program is the kick-off of the TX-100 blade testing at the three testing facilities.« less

On the inverse problem of blade design for centrifugal pumps and fans

NASA Astrophysics Data System (ADS)

Kruyt, N. P.; Westra, R. W.

2014-06-01

The inverse problem of blade design for centrifugal pumps and fans has been studied. The solution to this problem provides the geometry of rotor blades that realize specified performance characteristics, together with the corresponding flow field. Here a three-dimensional solution method is described in which the so-called meridional geometry is fixed and the distribution of the azimuthal angle at the three-dimensional blade surface is determined for blades of infinitesimal thickness. The developed formulation is based on potential-flow theory. Besides the blade impermeability condition at the pressure and suction side of the blades, an additional boundary condition at the blade surface is required in order to fix the unknown blade geometry. For this purpose the mean-swirl distribution is employed. The iterative numerical method is based on a three-dimensional finite element method approach in which the flow equations are solved on the domain determined by the latest estimate of the blade geometry, with the mean-swirl distribution boundary condition at the blade surface being enforced. The blade impermeability boundary condition is then used to find an improved estimate of the blade geometry. The robustness of the method is increased by specific techniques, such as spanwise-coupled solution of the discretized impermeability condition and the use of under-relaxation in adjusting the estimates of the blade geometry. Various examples are shown that demonstrate the effectiveness and robustness of the method in finding a solution for the blade geometry of different types of centrifugal pumps and fans. The influence of the employed mean-swirl distribution on the performance characteristics is also investigated.

Computational fluid dynamics study of the variable-pitch split-blade fan concept

NASA Technical Reports Server (NTRS)

Kepler, C. E.; Elmquist, A. R.; Davis, R. L.

1992-01-01

A computational fluid dynamics study was conducted to evaluate the feasibility of the variable-pitch split-blade supersonic fan concept. This fan configuration was conceived as a means to enable a supersonic fan to switch from the supersonic through-flow type of operation at high speeds to a conventional fan with subsonic inflow and outflow at low speeds. During this off-design, low-speed mode of operation, the fan would operate with a substantial static pressure rise across the blade row like a conventional transonic fan; the front (variable-pitch) blade would be aligned with the incoming flow, and the aft blade would remain fixed in the position set by the supersonic design conditions. Because of these geometrical features, this low speed configuration would inherently have a large amount of turning and, thereby, would have the potential for a large total pressure increase in a single stage. Such a high-turning blade configuration is prone to flow separation; it was hoped that the channeling of the flow between the blades would act like a slotted wing and help alleviate this problem. A total of 20 blade configurations representing various supersonic and transonic configurations were evaluated using a Navier Stokes CFD program called ADAPTNS because of its adaptive grid features. The flow fields generated by this computational procedure were processed by another data reduction program which calculated average flow properties and simulated fan performance. These results were employed to make quantitative comparisons and evaluations of blade performance. The supersonic split-blade configurations generated performance comparable to a single-blade supersonic, through-flow fan configuration. Simulated rotor total pressure ratios of the order of 2.5 or better were achieved for Mach 2.0 inflow conditions. The corresponding fan efficiencies were approximately 75 percent or better. The transonic split-blade configurations having large amounts of turning were able to generate large amounts of total turning and achieve simulated total pressure ratios of 3.0 or better with subsonic inflow conditions. These configurations had large losses and low fan efficiencies in the 70's percent. They had large separated regions and low velocity wakes. Additional turning and diffusion of this flow in a subsequent stator row would probably be very inefficient. The high total pressure ratios indicated by the rotor performance would be substantially reduced by the stators, and the stage efficiency would be substantially lower. Such performance leaves this dual-mode fan concept less attractive than originally postulated.

Weight Assessment for Fuselage Shielding on Aircraft With Open-Rotor Engines and Composite Blade Loss

NASA Technical Reports Server (NTRS)

Carney, Kelly; Pereira, Michael; Kohlman, Lee; Goldberg, Robert; Envia, Edmane; Lawrence, Charles; Roberts, Gary; Emmerling, William

2013-01-01

The Federal Aviation Administration (FAA) has been engaged in discussions with airframe and engine manufacturers concerning regulations that would apply to new technology fuel efficient "openrotor" engines. Existing regulations for the engines and airframe did not envision features of these engines that include eliminating the fan blade containment systems and including two rows of counter-rotating blades. Damage to the airframe from a failed blade could potentially be catastrophic. Therefore the feasibility of using aircraft fuselage shielding was investigated. In order to establish the feasibility of this shielding, a study was conducted to provide an estimate for the fuselage shielding weight required to provide protection from an open-rotor blade loss. This estimate was generated using a two-step procedure. First, a trajectory analysis was performed to determine the blade orientation and velocity at the point of impact with the fuselage. The trajectory analysis also showed that a blade dispersion angle of 3deg bounded the probable dispersion pattern and so was used for the weight estimate. Next, a finite element impact analysis was performed to determine the required shielding thickness to prevent fuselage penetration. The impact analysis was conducted using an FAA-provided composite blade geometry. The fuselage geometry was based on a medium-sized passenger composite airframe. In the analysis, both the blade and fuselage were assumed to be constructed from a T700S/PR520 triaxially-braided composite architecture. Sufficient test data on T700S/PR520 is available to enable reliable analysis, and also demonstrate its good impact resistance properties. This system was also used in modeling the surrogate blade. The estimated additional weight required for fuselage shielding for a wing- mounted counterrotating open-rotor blade is 236 lb per aircraft. This estimate is based on the shielding material serving the dual use of shielding and fuselage structure. If the shielding material is not used for dual purpose, and is only used for shielding, then the additional weight per aircraft is estimated to be 428 lb. This weight estimate is based upon a number of assumptions that would need to be revised when applying this concept to an actual airplane design. For example, the weight savings that will result when there is no fan blade containment system, manufacturing limitations which may increase the weight where variable thicknesses was assumed, engine placement on the wing versus aft fuselage, etc.

Preliminary structural design of composite main rotor blades for minimum weight

NASA Technical Reports Server (NTRS)

Nixon, Mark W.

1987-01-01

A methodology is developed to perform minimum weight structural design for composite or metallic main rotor blades subject to aerodynamic performance, material strength, autorotation, and frequency constraints. The constraints and load cases are developed such that the final preliminary rotor design will satisfy U.S. Army military specifications, as well as take advantage of the versatility of composite materials. A minimum weight design is first developed subject to satisfying the aerodynamic performance, strength, and autorotation constraints for all static load cases. The minimum weight design is then dynamically tuned to avoid resonant frequencies occurring at the design rotor speed. With this methodology, three rotor blade designs were developed based on the geometry of the UH-60A Black Hawk titanium-spar rotor blade. The first design is of a single titanium-spar cross section, which is compared with the UH-60A Black Hawk rotor blade. The second and third designs use single and multiple graphite/epoxy-spar cross sections. These are compared with the titanium-spar design to demonstrate weight savings from use of this design methodology in conjunction with advanced composite materials.

Use Deflected Trailing Edge to Improve the Aerodynamic Performance and Develop Low Solidity LPT Cascade

NASA Astrophysics Data System (ADS)

Chao, Li; Peigang, Yan; Xiangfeng, Wang; Wanjin, Han; Qingchao, Wang

2017-08-01

This paper investigates the feasibility of improving the aerodynamic performance of low pressure turbine (LPT) blade cascades and developing low solidity LPT blade cascades through deflected trailing edge. A deflected trailing edge improved aerodynamic performance of both LPT blade cascades and low solidity LPT blade cascades. For standard solidity LPT cascades, deflecting the trailing edge can decrease the energy loss coefficient by 20.61 % for a Reynolds number (Re) of 25,000 and freestream turbulence intensities (FSTI) of 1 %. For a low solidity LPT cascade, aerodynamic performance was also improved by deflecting the trailing edge. Solidity of the LPT cascade can be reduced by 12.5 % for blades with a deflected trailing edge without a drop in efficiency. Here, the flow control mechanism surrounding a deflected trailing edge was also revealed.

Application of a system modification technique to dynamic tuning of a spinning rotor blade

NASA Technical Reports Server (NTRS)

Spain, C. V.

1987-01-01

An important consideration in the development of modern helicopters is the vibratory response of the main rotor blade. One way to minimize vibration levels is to ensure that natural frequencies of the spinning main rotor blade are well removed from integer multiples of the rotor speed. A technique for dynamically tuning a finite-element model of a rotor blade to accomplish that end is demonstrated. A brief overview is given of the general purpose finite element system known as Engineering Analysis Language (EAL) which was used in this work. A description of the EAL System Modification (SM) processor is then given along with an explanation of special algorithms developed to be used in conjunction with SM. Finally, this technique is demonstrated by dynamically tuning a model of an advanced composite rotor blade.

Fiberglass composite blades for the 2 MW Mod-1 wind turbine generator

NASA Technical Reports Server (NTRS)

Batesole, W. R.

1982-01-01

In mid-1979, NASA contracted with Kaman Aerospace Corporation for the design, manufacture, and ground testing of two 100 foot composite rotor blades intended for operation on the Mod-1 wind turbine. The Mod-1 blades have been completed and are currently stored at the Kaman facility. The design, tooling, fabrication, and testing phases which have been carried out to date, as well as testing still planned are described. Discussed are differences from the 150 foot blade which were introduced for cost and manufacturing improvement purposes. Also included is a description of the lightning protection system installed in the blades, and its development program. Actual costs and manhours expended for Blade No. 2 are provided as a base, along with a projection of costs for the blade in production. Finally, cost drivers are identified relative to future designs.

Simulation of unsteady flows through stator and rotor blades of a gas turbine using the Chimera method

NASA Technical Reports Server (NTRS)

Nakamura, S.; Scott, J. N.

1993-01-01

A two-dimensional model to solve compressible Navier-Stokes equations for the flow through stator and rotor blades of a turbine is developed. The flow domains for the stator and rotor blades are coupled by the Chimera method that makes grid generation easy and enhances accuracy because the area of the grid that have high turning of grid lines or high skewness can be eliminated from the computational domain after the grids are generated. The results of flow computations show various important features of unsteady flows including the acoustic waves interacting with boundary layers, Karman vortex shedding from the trailing edge of the stator blades, pulsating incoming flow to a rotor blade from passing stator blades, and flow separation from both suction and pressure sides of the rotor blades.

Estimation of blade airloads from rotor blade bending moments

NASA Technical Reports Server (NTRS)

Bousman, William G.

1987-01-01

A method is developed to estimate the blade normal airloads by using measured flap bending moments; that is, the rotor blade is used as a force balance. The blade's rotation is calculated in vacuum modes and the airloads are then expressed as an algebraic sum of the mode shapes, modal amplitudes, mass distribution, and frequency properties. The modal amplitudes are identified from the blade bending moments using the Strain Pattern Analysis Method. The application of the method is examined using simulated flap bending moment data that have been calculated for measured airloads for a full-scale rotor in a wind tunnel. The estimated airloads are compared with the wind tunnel measurements. The effects of the number of measurements, the number of modes, and errors in the measurements and the blade properties are examined, and the method is shown to be robust.

Unified Aeroacoustics Analysis for High Speed Turboprop Aerodynamics and Noise. Volume 1; Development of Theory for Blade Loading, Wakes, and Noise

NASA Technical Reports Server (NTRS)

Hanson, D. B.

1991-01-01

A unified theory for the aerodynamics and noise of advanced turboprops are presented. Aerodynamic topics include calculation of performance, blade load distribution, and non-uniform wake flow fields. Blade loading can be steady or unsteady due to fixed distortion, counter-rotating wakes, or blade vibration. The aerodynamic theory is based on the pressure potential method and is therefore basically linear. However, nonlinear effects associated with finite axial induction and blade vortex flow are included via approximate methods. Acoustic topics include radiation of noise caused by blade thickness, steady loading (including vortex lift), and unsteady loading. Shielding of the fuselage by its boundary layer and the wing are treated in separate analyses that are compatible but not integrated with the aeroacoustic theory for rotating blades.

Aero-Thermo-Structural Design Optimization of Internally Cooled Turbine Blades

NASA Technical Reports Server (NTRS)

Dulikravich, G. S.; Martin, T. J.; Dennis, B. H.; Lee, E.; Han, Z.-X.

1999-01-01

A set of robust and computationally affordable inverse shape design and automatic constrained optimization tools have been developed for the improved performance of internally cooled gas turbine blades. The design methods are applicable to the aerodynamics, heat transfer, and thermoelasticity aspects of the turbine blade. Maximum use of the existing proven disciplinary analysis codes is possible with this design approach. Preliminary computational results demonstrate possibilities to design blades with minimized total pressure loss and maximized aerodynamic loading. At the same time, these blades are capable of sustaining significantly higher inlet hot gas temperatures while requiring remarkably lower coolant mass flow rates. These results suggest that it is possible to design internally cooled turbine blades that will cost less to manufacture, will have longer life span, and will perform as good, if not better than, film cooled turbine blades.

DESIGN OF TWO-DIMENSIONAL SUPERSONIC TURBINE ROTOR BLADES WITH BOUNDARY-LAYER CORRECTION

NASA Technical Reports Server (NTRS)

Goldman, L. J.

1994-01-01

A computer program has been developed for the design of supersonic rotor blades where losses are accounted for by correcting the ideal blade geometry for boundary layer displacement thickness. The ideal blade passage is designed by the method of characteristics and is based on establishing vortex flow within the passage. Boundary-layer parameters (displacement and momentum thicknesses) are calculated for the ideal passage, and the final blade geometry is obtained by adding the displacement thicknesses to the ideal nozzle coordinates. The boundary-layer parameters are also used to calculate the aftermixing conditions downstream of the rotor blades assuming the flow mixes to a uniform state. The computer program input consists essentially of the rotor inlet and outlet Mach numbers, upper- and lower-surface Mach numbers, inlet flow angle, specific heat ratio, and total flow conditions. The program gas properties are set up for air. Additional gases require changes to be made to the program. The computer output consists of the corrected rotor blade coordinates, the principal boundary-layer parameters, and the aftermixing conditions. This program is written in FORTRAN IV for batch execution and has been implemented on an IBM 7094. This program was developed in 1971.

Aeroelastic simulation of higher harmonic control

NASA Technical Reports Server (NTRS)

Robinson, Lawson H.; Friedmann, Peretz P.

1994-01-01

This report describes the development of an aeroelastic analysis of a helicopter rotor and its application to the simulation of helicopter vibration reduction through higher harmonic control (HHC). An improved finite-state, time-domain model of unsteady aerodynamics is developed to capture high frequency aerodynamic effects. An improved trim procedure is implemented which accounts for flap, lead-lag, and torsional deformations of the blade. The effect of unsteady aerodynamics is studied and it is found that its impact on blade aeroelastic stability and low frequency response is small, but it has a significant influence on rotor hub vibrations. Several different HHC algorithms are implemented on a hingeless rotor and their effectiveness in reducing hub vibratory shears is compared. All the controllers are found to be quite effective, but very differing HHC inputs are required depending on the aerodynamic model used. Effects of HHC on rotor stability and power requirements are found to be quite small. Simulations of roughly equivalent articulated and hingeless rotors are carried out, and it is found that hingeless rotors can require considerably larger HHC inputs to reduce vibratory shears. This implies that the practical implementation of HHC on hingeless rotors might be considerably more difficult than on articulated rotors.

Blade mistuning coupled with shaft flexibility effects in rotor aeroelasticity

NASA Technical Reports Server (NTRS)

Khader, Naim; Loewy, Robert G.

1989-01-01

The effect of bladed-disk polar dissymmetry, resulting from variations in mass from one blade to another, on aeroelastic stability boundaries for a fan stage is presented. In addition to both in-plane and out-of-plane deformations of the bladed-disk, bending of the supporting shaft in two planes is considered, and the resulting Coriolis forces and gyroscopic moments are included in the analysis. A quasi-steady aerodynamics approach is combined with the Lagrangian method to develop the governing equations of motion for the flexible bladed-disk-shaft assembly. Calculations are performed for an actual fan stage.

Analysis of temperature distribution in liquid-cooled turbine blades

NASA Technical Reports Server (NTRS)

Livingood, John N B; Brown, W Byron

1952-01-01

The temperature distribution in liquid-cooled turbine blades determines the amount of cooling required to reduce the blade temperature to permissible values at specified locations. This report presents analytical methods for computing temperature distributions in liquid-cooled turbine blades, or in simplified shapes used to approximate sections of the blade. The individual analyses are first presented in terms of their mathematical development. By means of numerical examples, comparisons are made between simplified and more complete solutions and the effects of several variables are examined. Nondimensional charts to simplify some temperature-distribution calculations are also given.

Emerging evidence in infection control: effecting change regarding use of disposable laryngoscope blades.

PubMed

Machan, Melissa D; Monaghan, W Patrick; McDonough, John; Hogan, Gerard

2013-04-01

The purpose of this evidence-based project was to determine the perceptions of anesthesia providers regarding the use of disposable laryngoscope blades. Frequency of use, ease of use, and complications encountered when using the disposable blade were evaluated before and after an in-service program designed to increase the use of disposable blades. Participants completed an anonymous questionnaire about their knowledge and practice regarding disposable laryngoscope blades. Then they received an investigator-developed article to read about the best and most recent practices regarding disposable laryngoscope blades. The same anonymous questionnaire was completed 3 months later. Inventory of the disposable laryngoscope blades was collected before the project and 1 and 3 months later. After the intervention, 25% of anesthesia providers described performance as their reason for not using the disposable laryngoscope blade, which was down from 60% at the project's start. Inventory showed a 23% increase in use of disposable laryngoscope blades after the intervention, which a single-proportion Z test showed was statistically significant (Z = 2.046, P = .041). This evidence-based project shows that a change in practice was evident after dissemination of the best and most recent clinical evidence regarding laryngoscope blades, which should translate to improved patient outcomes.

Development and application of a method for predicting rotor free wake positions and resulting rotor blade air loads. Volume 1: Model and results

NASA Technical Reports Server (NTRS)

Sadler, S. G.

1971-01-01

Rotor wake geometries are predicted by a process similar to the startup of a rotor in a free stream. An array of discrete trailing and shed vortices is generated with vortex strengths corresponding to stepwise radial and azimuthal blade circulations. The array of shed and trailing vortices is limited to an arbitrary number of azimuthal steps behind each blade. The remainder of the wake model of each blade is an arbitrary number of trailing vortices. Vortex element end points were allowed to be transported by the resultant velocity of the free stream and vortex-induced velocities. Wake geometry, wake flow, and wake-induced velocity influence coefficients are generated by this program for use in the blade loads portion of the calculations. Blade loads computations include the effects of nonuniform inflow due to a free wake, nonlinear airfoil characteristics, and response of flexible blades to the applied loads. Computed wake flows and blade loads are compared with experimentally measured data. Predicted blade loads, response and shears and moments are obtained for a model rotor system having two independent rotors. The effects of advance ratio, vertical separation of rotors, different blade radius ratios, and different azimuthal spacing of the blades of one rotor with respect to the other are investigated.

Temperatures and Stresses on Hollow Blades For Gas Turbines

NASA Technical Reports Server (NTRS)

Pollmann, Erich

1947-01-01

The present treatise reports on theoretical investigations and test-stand measurements which were carried out in the BMW Flugmotoren GMbH in developing the hollow blade for exhaust gas turbines. As an introduction the temperature variation and the stress on a turbine blade for a gas temperature of 900 degrees and circumferential velocities of 600 meters per second are discussed. The assumptions onthe heat transfer coefficients at the blade profile are supported by tests on an electrically heated blade model. The temperature distribution in the cross section of a blade Is thoroughly investigated and the temperature field determined for a special case. A method for calculation of the thermal stresses in turbine blades for a given temperature distribution is indicated. The effect of the heat radiation on the blade temperature also is dealt with. Test-stand experiments on turbine blades are evaluated, particularly with respect to temperature distribution in the cross section; maximum and minimum temperature in the cross section are ascertained. Finally, the application of the hollow blade for a stationary gas turbine is investigated. Starting from a setup for 550 C gas temperature the improvement of the thermal efficiency and the fuel consumption are considered as well as the increase of the useful power by use of high temperatures. The power required for blade cooling is taken into account.

An analysis of thermal stress and gas bending effects on vibrations of compressor rotor stages. [blade torsional rigidity

NASA Technical Reports Server (NTRS)

Chen, L.-T.; Dugundji, J.

1979-01-01

A preliminary study conducted by Kerrebrock et al. (1976) has shown that the torsional rigidity of untwisted thin blades of a transonic compressor can be reduced significantly by transient thermal stresses. The aerodynamic loads have various effects on blade vibration. One effect is that gas bending loads may result in a bending-torsion coupling which may change the characteristics of the torsion and bending vibration of the blade. For a general study of transient-temperature distribution within a rotor stage, a finite-element heat-conduction analysis was developed. The blade and shroud are divided into annular elements. With a temperature distribution obtained from the heat-conduction analysis and a prescribed gas bending load distribution along the blade span, the static deformation and moment distributions of the blade can be solved iteratively using the finite-element method. The reduction of the torsional rigidity of pretwisted blades caused by the thermal stress effect is then computed. The dynamic behavior of the blade is studied by a modified Galerkin's method.

A modal aeroelastic analysis scheme for turbomachinery blading. M.S. Thesis - Case Western Reserve Univ. Final Report

NASA Technical Reports Server (NTRS)

Smith, Todd E.

1991-01-01

An aeroelastic analysis is developed which has general application to all types of axial-flow turbomachinery blades. The approach is based on linear modal analysis, where the blade's dynamic response is represented as a linear combination of contributions from each of its in-vacuum free vibrational modes. A compressible linearized unsteady potential theory is used to model the flow over the oscillating blades. The two-dimensional unsteady flow is evaluated along several stacked axisymmetric strips along the span of the airfoil. The unsteady pressures at the blade surface are integrated to result in the generalized force acting on the blade due to simple harmonic motions. The unsteady aerodynamic forces are coupled to the blade normal modes in the frequency domain using modal analysis. An iterative eigenvalue problem is solved to determine the stability of the blade when the unsteady aerodynamic forces are included in the analysis. The approach is demonstrated by applying it to a high-energy subsonic turbine blade from a rocket engine turbopump power turbine. The results indicate that this turbine could undergo flutter in an edgewise mode of vibration.

An experimental study of the compressor rotor blade boundary layer

NASA Technical Reports Server (NTRS)

Pouagare, M.; Lakshminarayana, B.; Galmes, J. M.

1984-01-01

The three-dimensional turbulent boundary layer developing on a rotor blade of an axial flow compressor was measured using a miniature 'x' configuration hot-wire probe. The measurements were carried out at nine radial locations on both surfaces of the blade at various chordwise locations. The data derived includes streamwise and radial mean velocities and turbulence intensities. The validity of conventional velocity profiles such as the 'power law profile' for the streamwise profile, and Mager and Eichelbrenner's for the radial profile, is examined. A modification to Mager's crossflow profile is proposed. Away from the blade tip, the streamwise component of the blade boundary layer seems to be mainly influenced by the streamwise pressure gradient. Near the tip of the blade, the behavior of the blade boundary layer is affected by the tip leakage flow and the annulus wall boundary layer. The 'tangential blockage' due to the blade boundary layer is derived from the data. The profile losses are found to be less than that of an equivalent cascade, except in the tip region of the blade.

Low-cost directionally-solidified turbine blades, volume 1

NASA Technical Reports Server (NTRS)

Sink, L. W.; Hoppin, G. S., III; Fujii, M.

1979-01-01

A low cost process of manufacturing high stress rupture strength directionally-solidified high pressure turbine blades was successfully developed for the TFE731-3 Turbofan Engine. The basic processing parameters were established using MAR-M 247 and employing the exothermic directional-solidification process in trial castings of turbine blades. Nickel-based alloys were evaluated as directionally-solidified cast blades. A new turbine blade, disk, and associated components were then designed using previously determined material properties. Engine tests were run and the results were analyzed and compared to the originally established goals. The results showed that the stress rupture strength of exothermically heated, directionally-solidified MAR-M 247 turbine blades exceeded program objectives and that the performance and cost reduction goals were achieved.

Wind-Tunnel Evaluation of the Effect of Blade Nonstructural Mass Distribution on Helicopter Fixed-System Loads

NASA Technical Reports Server (NTRS)

Wilbur, Matthew L.; Yeager, William T., Jr.; Singleton, Jeffrey D.; Mirick, Paul H.; Wilkie, W. Keats

1998-01-01

This report provides data obtained during a wind-tunnel test conducted to investigate parametrically the effect of blade nonstructural mass on helicopter fixed-system vibratory loads. The data were obtained with aeroelastically scaled model rotor blades that allowed for the addition of concentrated nonstructural masses at multiple locations along the blade radius. Testing was conducted for advance ratios ranging from 0.10 to 0.35 for 10 blade-mass configurations. Three thrust levels were obtained at representative full-scale shaft angles for each blade-mass configuration. This report provides the fixed-system forces and moments measured during testing. The comprehensive database obtained is well-suited for use in correlation and development of advanced rotorcraft analyses.

Design, evaluation, and fabrication of low-cost composite blades for intermediate-size wind turbines

NASA Technical Reports Server (NTRS)

Weingart, O.

1981-01-01

Low cost approaches for production of 60 ft long glass fiber/resin composite rotor blades for the MOD-OA wind turbine were identified and evaluated. The most cost-effective configuration was selected for detailed design. Subelement and subscale specimens were fabricated for testing to confirm physical and mechanical properties of the composite blade materials, to develop and evaluate blade fabrication techniques and processes, and to confirm the structural adequacy of the root end joint. Full-scale blade tooling was constructed and a partial blade for tool and process tryout was built. Then two full scale blades were fabricated and delivered to NASA-LeRC for installation on a MOD-OA wind turbine at Clayton, New Mexico for operational testing. Each blade was 60 ft. long with 4.5 ft. chord at root end and 2575 lbs weight including metal hub adapter. The selected blade configuration was a three cell design constructed using a resin impregnated glass fiber tape winding process that allows rapid wrapping of primarily axially oriented fibers onto a tapered mandrel, with tapered wall thickness. The ring winder/transverse filament tape process combination was used for the first time on this program to produce entire rotor blade structures. This approach permitted the complete blade to be wound on stationary mandrels, an improvement which alleviated some of the tooling and process problems encountered on previous composite blade programs.

Vibration and flutter characteristics of the SR7L large-scale propfan

NASA Technical Reports Server (NTRS)

August, Richard; Kaza, Krishna Rao V.

1988-01-01

An investigation of the vibration characteristics and aeroelastic stability of the SR7L Large-Scale Advanced Propfan was performed using a finite element blade model and an improved aeroelasticity code. Analyses were conducted for different blade pitch angles, blade support conditions, number of blades, rotational speeds, and freestream Mach numbers. A finite element model of the blade was used to determine the blade's vibration behavior and sensitivity to support stiffness. The calculated frequencies and mode shape obtained with this model agreed well with the published experimental data. A computer code recently developed at NASA Lewis Research Center and based on three-dimensional, unsteady, lifting surface aerodynamic theory was used for the aeroelastic analysis to examine the blade's stability at a cruise condition of Mach 0.8 at 1700 rpm. The results showed that the blade is stable for that operating point. However, a flutter condition was predicted if the cruise Mach number was increased to 0.9.

Optimization of blade motion of vertical axis turbine

NASA Astrophysics Data System (ADS)

Ma, Yong; Zhang, Liang; Zhang, Zhi-yang; Han, Duan-feng

2016-04-01

In this paper, a method is proposed to improve the energy efficiency of the vertical axis turbine. First of all, a single disk multiple stream-tube model is used to calculate individual fitness. Genetic algorithm is adopted to optimize blade pitch motion of vertical axis turbine with the maximum energy efficiency being selected as the optimization objective. Then, a particular data processing method is proposed, fitting the result data into a cosine-like curve. After that, a general formula calculating the blade motion is developed. Finally, CFD simulation is used to validate the blade pitch motion formula. The results show that the turbine's energy efficiency becomes higher after the optimization of blade pitch motion; compared with the fixed pitch turbine, the efficiency of variable-pitch turbine is significantly improved by the active blade pitch control; the energy efficiency declines gradually with the growth of speed ratio; besides, compactness has lager effect on the blade motion while the number of blades has little effect on it.

Applying Dynamic Wake Models to Induced Power Calculations for an Optimum Rotor

DTIC Science & Technology

2009-08-01

versions being special cases of the general one. Although the rotor blade may be moving at transonic speeds near the tip, the rotor wake is...The effect of a finite number of blades incurs an additional loss in wake energy due to the individual vortex sheets from each blade . In 1929... blades . Up to this point, previous developments have been able to achieve the full description of the wake in all ranges of flight regime

The Slotted Blade Axial-Flow Blower

DTIC Science & Technology

1955-09-01

YORK 18, NEW YORK w is|’ .THE SLOTTED BLADE AXIAL-FLOW BLOVER AUG 0 1 13941J F Dr. H. E. Sheets, Member ASME Chief Research and Development Engineer ... blades of an axial flow blower. The subject of boundary-layer control has attracted considerable attention in respect to the isolated airfoil (1)1 but... blades . Flow through airfoils displays a region of laminar flow beginning at the leading edge. Further downstream, at approximately the location of the

Investigation of Rotor Performance and Loads of a UH-60A Individual Blade Control System

DTIC Science & Technology

2010-05-01

the pitch link for each rotor blade with an actuator so that the blade root pitch angles could be changed independently. This design was previously...with the ultimate goal of providing the technology for timely and cost-effective design and development of new rotors. Analytical studies on IBC [8...rotor with coincident flap and lag articulation provided at the blade root by elastomeric bearings. This bearing, through the rotor spindle , also

Small Laminated Axial Turbine Design and Test Program.

DTIC Science & Technology

1980-12-01

ILLUSTRATIONS Figure No. Title Page 1 Typical Test Results from TFE731 -3 Hot-Rig Testing. 5 2 Laminated Blade Chordwise Flow Patterns 8 3 Laminated Blade Cooling...Flow Parameter Versus Pressure Ratio 36 24 Blade Flow Distribution 37 25 TFE731 Turbofan Engine 38 26 Laminated Turbine Wheel 40 27 Selected Blade...facility, which was specifically developed to permit evaluation of cooled compo- nents for gas turbine engines. Four TFE731 -3 Laminated Turbine Wheels

Development of a Novel Erosion Resistant Coating System for Use on Rotorcraft Blades

DTIC Science & Technology

2012-05-01

Technologies Research Center (UTRC) and Sikorsky utilizes a two part metal/ cermet coating system on the leading edge of the blades to provide unmatched...ARL, United Technologies Research Center (UTRC) and Sikorsky utilizes a two part metal/ cermet coating system on the leading edge of the blades to...Rotor Blade Tip Fairing A study by Ely et.al. evaluated dozens of coating technologies and down-selected a two-part metal/ceramic coating system on

The performance & flow visualization studies of three-dimensional (3-D) wind turbine blade models

NASA Astrophysics Data System (ADS)

Sutrisno, Prajitno, Purnomo, W., Setyawan B.

2016-06-01

Recently, studies on the design of 3-D wind turbine blades have a less attention even though 3-D blade products are widely sold. In contrary, advanced studies in 3-D helicopter blade tip have been studied rigorously. Studies in wind turbine blade modeling are mostly assumed that blade spanwise sections behave as independent two-dimensional airfoils, implying that there is no exchange of momentum in the spanwise direction. Moreover, flow visualization experiments are infrequently conducted. Therefore, a modeling study of wind turbine blade with visualization experiment is needed to be improved to obtain a better understanding. The purpose of this study is to investigate the performance of 3-D wind turbine blade models with backward-forward swept and verify the flow patterns using flow visualization. In this research, the blade models are constructed based on the twist and chord distributions following Schmitz's formula. Forward and backward swept are added to the rotating blades. Based on this, the additional swept would enhance or diminish outward flow disturbance or stall development propagation on the spanwise blade surfaces to give better blade design. Some combinations, i. e., b lades with backward swept, provide a better 3-D favorable rotational force of the rotor system. The performance of the 3-D wind turbine system model is measured by a torque meter, employing Prony's braking system. Furthermore, the 3-D flow patterns around the rotating blade models are investigated by applying "tuft-visualization technique", to study the appearance of laminar, separated, and boundary layer flow patterns surrounding the 3-dimentional blade system.

Advanced turboprop aircraft flyover noise: Annoyance to counter-rotating-propeller configurations with a different number of blades on each rotor: Preliminary results

NASA Technical Reports Server (NTRS)

Mccurdy, David A.

1988-01-01

A laboratory experiment was conducted to quantify the annoyance of people to the flyover noise of advanced turboprop aircraft with counter-rotating propellers (CRP) having a different number of blades on each rotor (nxm, e.g., 10 x 8, 12 x 11). The objectives were: (1) compare annoyance to nxm CRP advanced turboprop aircraft with annoyance to conventional turboprop and jet aircraft; (2) determine the effects of tonal content on annoyance; and (3) determine the ability of aircraft noise measurement procedures and corrections to predict annoyance for this new class of aircraft. A computer synthesis system was used to generate 35 realistic, time-varying simulations of advanced turboprop takeoff noise in which the tonal content was systematically varied to represent combinations of 15 fundamental frequency (blade passage frequency) combinations and three tone-to-broadband noise ratios. The fundamental frequencies, which represented blade number combinations from 6 x 5 to 13 x 12 and 7 x 5 to 13 x 11, ranged from 112.5 to 292.5 Hz. The three tone-to-broadband noise ratios were 0, 15, and 30 dB. These advanced turboprop simulations along with recordings of five conventional turboprop takeoffs and five conventional jet takeoffs were presented at D-weighted sound pressure levels of 70, 80, and 90 dB to 64 subjects in an anechoic chamber. Analyses of the subjects' annoyance judgments compare the three categories of aircraft and examine the effects of the differences in tonal content among the advanced turboprop noises. The annoyance prediction ability of various noise measurement procedures and corrections is also examined.

Simulation of 3-D viscous compressible flow in multistage turbomachinery by finite element methods

NASA Astrophysics Data System (ADS)

Sleiman, Mohamad

1999-11-01

The flow in a multistage turbomachinery blade row is compressible, viscous, and unsteady. Complex flow features such as boundary layers, wake migration from upstream blade rows, shocks, tip leakage jets, and vortices interact together as the flow convects through the stages. These interactions contribute significantly to the aerodynamic losses of the system and degrade the performance of the machine. The unsteadiness also leads to blade vibration and a shortening of its life. It is therefore difficult to optimize the design of a blade row, whether aerodynamically or structurally, in isolation, without accounting for the effects of the upstream and downstream rows. The effects of axial spacing, blade count, clocking (relative position of follow-up rotors with respect to wakes shed by upstream ones), and levels of unsteadiness may have a significance on performance and durability. In this Thesis, finite element formulations for the simulation of multistage turbomachinery are presented in terms of the Reynolds-averaged Navier-Stokes equations for three-dimensional steady or unsteady, viscous, compressible, turbulent flows. Three methodologies are presented and compared. First, a steady multistage analysis using a a-mixing- plane model has been implemented and has been validated against engine data. For axial machines, it has been found that the mixing plane simulation methods match very well the experimental data. However, the results for a centrifugal stage, consisting of an impeller followed by a vane diffuser of equal pitch, show flagrant inconsistency with engine performance data, indicating that the mixing plane method has been found to be inappropriate for centrifugal machines. Following these findings, a more complete unsteady multistage model has been devised for a configuration with equal number of rotor and stator blades (equal pitches). Non-matching grids are used at the rotor-stator interface and an implicit interpolation procedure devised to ensure continuity of fluxes across. This permits the rotor and stator equations to be solved in a fully- coupled manner, allowing larger time steps in attaining a time-periodic solution. This equal pitch approach has been validated on the complex geometry of a centrifugal stage. Finally, for a stage configuration with unequal pitches, the time-inclined method, developed by Giles (1991) for 2-D viscous compressible flow, has been extended to 3-D and formulated in terms of the physical solution vector U, rather than Q, a non-physical one. The method has been evaluated for unsteady flow through a rotor blade passage of the power turbine of a turboprop.

COLLABORATIVE RESEARCH AND DEVELOPMENT (CR&D) Delivery Order 0068: Anti-fretting Coatings Research and Development

DTIC Science & Technology

2008-02-01

reduction in fatigue strength [10]. One common mitigation strategy to the fretting wear/fatigue problem in titanium alloy compressor blades is to...inter-metallic fretting wear between Ti6Al4V ( Titanium , 6% Aluminum, 4% Vanadium) and cold-sprayed, commercially pure nickel coatings. The results...fretting in an aircraft turbine engine is in the compressor section at the blade /disk interface. The blade /disk interface, also known as the

TADS--A CFD-Based Turbomachinery Analysis and Design System with GUI: User's Manual. 2.0

NASA Technical Reports Server (NTRS)

Koiro, M. J.; Myers, R. A.; Delaney, R. A.

1999-01-01

The primary objective of this study was the development of a Computational Fluid Dynamics (CFD) based turbomachinery airfoil analysis and design system, controlled by a Graphical User Interface (GUI). The computer codes resulting from this effort are referred to as TADS (Turbomachinery Analysis and Design System). This document is intended to serve as a User's Manual for the computer programs which comprise the TADS system, developed under Task 18 of NASA Contract NAS3-27350, ADPAC System Coupling to Blade Analysis & Design System GUI and Task 10 of NASA Contract NAS3-27394, ADPAC System Coupling to Blade Analysis & Design System GUI, Phase II-Loss, Design and, Multi-stage Analysis. TADS couples a throughflow solver (ADPAC) with a quasi-3D blade-to-blade solver (RVCQ3D) in an interactive package. Throughflow analysis and design capability was developed in ADPAC through the addition of blade force and blockage terms to the governing equations. A GUI was developed to simplify user input and automate the many tasks required to perform turbomachinery analysis and design. The coupling of the various programs was done in such a way that alternative solvers or grid generators could be easily incorporated into the TADS framework. Results of aerodynamic calculations using the TADS system are presented for a highly loaded fan, a compressor stator, a low speed turbine blade and a transonic turbine vane.

Blade resonance parameter identification based on tip-timing method without the once-per revolution sensor

NASA Astrophysics Data System (ADS)

Guo, Haotian; Duan, Fajie; Zhang, Jilong

2016-01-01

Blade tip-timing is the most effective method for blade vibration online measurement of turbomachinery. In this article a synchronous resonance vibration measurement method of blade based on tip-timing is presented. This method requires no once-per revolution sensor which makes it more generally applicable in the condition where this sensor is difficult to install, especially for the high-pressure rotors of dual-rotor engines. Only three casing mounted probes are required to identify the engine order, amplitude, natural frequency and the damping coefficient of the blade. A method is developed to identify the blade which a tip-timing data belongs to without once-per revolution sensor. Theoretical analyses of resonance parameter measurement are presented. Theoretic error of the method is investigated and corrected. Experiments are conducted and the results indicate that blade resonance parameter identification is achieved without once-per revolution sensor.

Technical Assessment of the National Full Scale Aerodynamic Complex Fan Blades Repair

NASA Technical Reports Server (NTRS)

Young, Clarence P., Jr.; Dixon, Peter G.; St.Clair, Terry L.; Johns, William E.

1998-01-01

This report describes the principal activities of a technical review team formed to address National Full Scale Aerodynamic Complex (NFAC) blade repair problems. In particular, the problem of lack of good adhesive bonding of the composite overwrap to the Hyduliginum wood blade material was studied extensively. Description of action plans and technical elements of the plans are provided. Results of experiments designed to optimize the bonding process and bonding strengths obtained on a full scale blade using a two-step cure process with adhesive primers are presented. Consensus recommendations developed by the review team in conjunction with the NASA Ames Fan Blade Repair Project Team are provided along with lessons learned on this program. Implementation of recommendations resulted in achieving good adhesive bonds between the composite materials and wooden blades, thereby providing assurance that the repaired fan blades will meet or exceed operational life requirements.

Definition of a 5-MW Reference Wind Turbine for Offshore System Development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jonkman, J.; Butterfield, S.; Musial, W.

2009-02-01

This report describes a three-bladed, upwind, variable-speed, variable blade-pitch-to-feather-controlled multimegawatt wind turbine model developed by NREL to support concept studies aimed at assessing offshore wind technology.

Thin-film sensors for space propulsion technology: Fabrication and preparation for testing

NASA Technical Reports Server (NTRS)

Kim, Walter S.; Hepp, Aloysius F.

1989-01-01

The goal of this work is to develop and test thin-film thermocouples for Space Shuttle Main Engine (SSME) components. Thin-film thermocouples have been developed for aircraft gas turbine engines and are in use for temperature measurement on turbine blades up to 1800 F. Established aircraft engine gas turbine technology is currently being adapted to turbine engine blade materials and the environment encountered in the SSME, especially severe thermal shock from cryogenic fuel to combustion temperatures. Initial results using coupons of MAR M-246 (+Hf) and PWA 1480 have been followed by fabrication of thin-film thermocouples on SSME turbine blades. Current efforts are focused on preparing for testing in the Turbine Blade Tester at the NASA Marshall Space Flight Center (MSFC). Future work will include testing of thin-film thermocouples on SSME blades of single crystal PWA 1480 at MSFC.

An Idealized, Single Radial Swirler, Lean-Direct-Injection (LDI) Concept Meshing Script

NASA Technical Reports Server (NTRS)

Iannetti, Anthony C.; Thompson, Daniel

2008-01-01

To easily study combustor design parameters using computational fluid dynamics codes (CFD), a Gridgen Glyph-based macro (based on the Tcl scripting language) dubbed BladeMaker has been developed for the meshing of an idealized, single radial swirler, lean-direct-injection (LDI) combustor. BladeMaker is capable of taking in a number of parameters, such as blade width, blade tilt with respect to the perpendicular, swirler cup radius, and grid densities, and producing a three-dimensional meshed radial swirler with a can-annular (canned) combustor. This complex script produces a data format suitable for but not specific to the National Combustion Code (NCC), a state-of-the-art CFD code developed for reacting flow processes.

Laboratory Experiments on the Effects of Blade Strike from Hydrokinetic Energy Technologies on Larval and Juvenile Freshwater Fishes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schweizer, Peter E; Cada, Glenn F; Bevelhimer, Mark S

2012-03-01

There is considerable interest in the development of marine and hydrokinetic energy projects in rivers, estuaries, and coastal ocean waters of the United States. Hydrokinetic (HK) technologies convert the energy of moving water in river or tidal currents into electricity, without the impacts of dams and impoundments associated with conventional hydropower or the extraction and combustion of fossil fuels. The Federal Energy Regulatory Commission (FERC) maintains a database that displays the geographical distribution of proposed HK projects in inland and tidal waters (FERC 2012). As of March 2012, 77 preliminary permits had been issued to private developers to study HKmore » projects in inland waters, the development of which would total over 8,000 MW. Most of these projects are proposed for the lower Mississippi River. In addition, the issuance of another 27 preliminary permits for HK projects in inland waters, and 3 preliminary permits for HK tidal projects (totaling over 3,100 MW) were under consideration by FERC. Although numerous HK designs are under development (see DOE 2009 for a description of the technologies and their potential environmental effects), the most commonly proposed current-based projects entail arrays of rotating devices, much like submerged wind turbines, that are positioned in the high-velocity (high energy) river channels. The many diverse HK designs imply a diversity of environmental impacts, but a potential impact common to most is the risk for blade strike to aquatic organisms. In conventional hydropower generation, research on fish passage through reaction turbines at low-head dams suggested that strike and mortality for small fish could be low. As a consequence of the large surface area to mass ratio of small fish, the drag forces in the boundary layer flow at the surface of a rotor blade may pull small fish around the leading edge of a rotor blade without making physical contact (Turnpenny 1998, Turnpenny et al. 2000). Although there is concern that small, fragile fish early life stages may be unable to avoid being struck by the blades of hydrokinetic turbines, we found no empirical data in the published literature that document survival of earliest life-stage fish in passage by rotor blades. In addition to blade strike, research on passage of fish through conventional hydropower turbines suggested that fish mortalities from passage through the rotor swept area could also occur due to shear stresses and pressure chances in the water column (Cada et al. 1997, Turnpenny 1998). However, for most of the proposed HK turbine designs the rotors are projected to operate a lower RPM (revolutions per minute) than observed from conventional reaction turbines; the associated shear stress and pressure changes are expected to be lower and pose a smaller threat to fish survival (DOE 2009). Only a limited number of studies have been conducted to examine the risk of blade strike from hydrokinetic technologies to fish (Turnpenny et al. 1992, Normandeau et al. 2009, Seitz et al. 2011, EPRI 2011); the survival of drifting or weakly swimming fish (especially early life stages) that encounter rotor blades from hydrokinetic (HK) devices is currently unknown. Our study addressed this knowledge gap by testing how fish larvae and juveniles encountered different blade profiles of hydrokinetic devices and how such encounters influenced survivorship. We carried out a laboratory study designed to improve our understanding of how fish larvae and juvenile fish may be affected by encounters with rotor blades from HK turbines in the water column of river and ocean currents. (For convenience, these early life stages will be referred to as young of the year, YOY). The experiments developed information needed to quantify the risk (both probability and consequences) of rotor-blade strike to YOY fish. In particular, this study attempted to determine whether YOY drifting in a high-velocity flow directly in the path of the blade leading edge will make contact with the rotor blade or will bypass the blade while entrained in the boundary layer of water flowing over the blade surface. The study quantified both immediate and delayed mortalities (observed immediately, 3 hours, and 24 hours after encountering the blade) among freshwater YOY fish resulting from contact with the blade or turbulent flows in the wake of the blade.« less

Composite rotor blades for large wind energy installations

NASA Technical Reports Server (NTRS)

Kussmann, A.; Molly, J.; Muser, D.

1980-01-01

The design of large wind power systems in Germany is reviewed with attention given to elaboration of the total wind energy system, aerodynamic design of the rotor blade, and wind loading effects. Particular consideration is given to the development of composite glass fiber/plastic or carbon fiber/plastic rotor blades for such installations.

Forced response analysis of an aerodynamically detuned supersonic turbomachine rotor

NASA Technical Reports Server (NTRS)

Hoyniak, D.; Fleeter, S.

1985-01-01

High performance aircraft-engine fan and compressor blades are vulnerable to aerodynamically forced vibrations generated by inlet flow distortions due to wakes from upstream blade and vane rows, atmospheric gusts, and maldistributions in inlet ducts. In this report, an analysis is developed to predict the flow-induced forced response of an aerodynamically detuned rotor operating in a supersonic flow with a subsonic axial component. The aerodynamic detuning is achieved by alternating the circumferential spacing of adjacent rotor blades. The total unsteady aerodynamic loading acting on the blading, as a result of the convection of the transverse gust past the airfoil cascade and the resulting motion of the cascade, is developed in terms of influence coefficients. This analysis is used to investigate the effect of aerodynamic detuning on the forced response of a 12-blade rotor, with Verdon's Cascade B flow geometry as a uniformly spaced baseline configuration. The results of this study indicate that, for forward traveling wave gust excitations, aerodynamic detuning is very beneficial, resulting in significantly decreased maximum-amplitude blade responses for many interblade phase angles.

Annulus wall boundary layer development in a compressor stage, including the effects of tip clearance

NASA Technical Reports Server (NTRS)

Lakshminarayana, B.; Murthy, K. N. S.; Pouagare, M.; Govindan, T. R.

1983-01-01

The end-wall boundary layer development in a compressor stage, including the inlet guide vane (IGV) passage and the rotor passage, was measured. The measurement upstream of the rotor and inside the IGV passage were carried out with a five-hole probe. The data (blade-to-blade) inside the IGV passage were carried out with a five-hole probe. The data (blade-to-blade) inside the rotor passage were measured using a three-sensor rotating hot-wire below the tip clearance region and "V' configuration probe inside the clearance region. The rotor exit measurements (blade-to-blade) were acquired with a laser Doppler velocimeter. The velocity profiles and the integral properties are presented and interpreted. The boundary layer is comparatively well behaved up to the leading edge of the rotor, beyond which complex interactions result in very unconventional profiles. The momentum thicknesses decrease in the leakage flow region of the rotor. The momentum thicknesses and the limiting streamline angles predicted from a momentum integral technique agree well with the data up to the leading edge of the rotor.

Control Study for Five-axis Dynamic Spin Rig Using Magnetic Bearings

NASA Technical Reports Server (NTRS)

Choi, Benjamin; Johnson, Dexter; Provenza, Andrew; Morrison, Carlos; Montague, Gerald

2003-01-01

The NASA Glenn Research Center (GRC) has developed a magnetic bearing system for the Dynamic Spin Rig (DSR) with a fully suspended shaft that is used to perform vibration tests of turbomachinery blades and components under spinning conditions in a vacuum. Two heteropolar radial magnetic bearings and a thrust magnetic bearing and the associated control system were integrated into the DSR to provide magnetic excitation as well as non-contact mag- netic suspension of a 15.88 kg (35 lb) vertical rotor with blades to induce turbomachinery blade vibration. For rotor levitation, a proportional-integral-derivative (PID) controller with a special feature for multidirectional radial excitation worked well to both support and shake the shaft with blades. However, more advanced controllers were developed and successfully tested to determine the optimal controller in terms of sensor and processing noise reduction, smaller rotor orbits, more blade vibration amplitude, and energy savings for the system. The test results of a variety of controllers that were demonstrated up to 10.000 rpm are shown. Furthermore, rotor excitation operation and conceptual study of active blade vibration control are addressed.

Analysis and control on changeable wheel tool system of hybrid grinding and polishing machine tool for blade finishing

NASA Astrophysics Data System (ADS)

He, Qiuwei; Lv, Xingming; Wang, Xin; Qu, Xingtian; Zhao, Ji

2017-01-01

Blade is the key component in the energy power equipment of turbine, aircraft engines and so on. Researches on the process and equipment for blade finishing become one of important and difficult point. To control precisely tool system of developed hybrid grinding and polishing machine tool for blade finishing, the tool system with changeable wheel for belt polishing is analyzed in this paper. Firstly, the belt length and wrap angle of each wheel in different position of tension wheel swing angle in the process of changing wheel is analyzed. The reasonable belt length is calculated by using MATLAB, and relationships between wrap angle of each wheel and cylinder expansion amount of contact wheel are obtained. Then, the control system for changeable wheel tool structure is developed. Lastly, the surface roughness of blade finishing is verified by experiments. Theoretical analysis and experimental results show that reasonable belt length and wheel wrap angle can be obtained by proposed analysis method, the changeable wheel tool system can be controlled precisely, and the surface roughness of blade after grinding meets the design requirements.

Project Boomerang

ERIC Educational Resources Information Center

King, Allen L.

1975-01-01

Describes an experimental project on boomerangs designed for an undergraduate course in classical mechanics. The students designed and made their own boomerangs, devised their own procedures, and carried out suitable measurements. Presents some of their data and a simple analysis for the two-bladed boomerang. (Author/MLH)

Advanced optical blade tip clearance measurement system

NASA Technical Reports Server (NTRS)

Ford, M. J.; Honeycutt, R. E.; Nordlund, R. E.; Robinson, W. W.

1978-01-01

An advanced electro-optical system was developed to measure single blade tip clearances and average blade tip clearances between a rotor and its gas path seal in an operating gas turbine engine. This system is applicable to fan, compressor, and turbine blade tip clearance measurement requirements, and the system probe is particularly suitable for operation in the extreme turbine environment. A study of optical properties of blade tips was conducted to establish measurement system application limitations. A series of laboratory tests was conducted to determine the measurement system's operational performance characteristics and to demonstrate system capability under simulated operating gas turbine environmental conditions. Operational and environmental performance test data are presented.

Development of low-cost directionally-solidified turbine blades

NASA Technical Reports Server (NTRS)

Hoppin, G. S., III; Fujii, M.; Sink, L. W.

1980-01-01

A low-cost directionally solidified (DS) casting of turbine blades of high stress rupture is discussed. The process uses an exothermically heated mold; a newly designed solid blade was cast for the high-pressure turbine of the TFE731-3 turbofan engine. Ni-based alloys Mar-M 247 and Mar-M 200 + Hf were used. The solid DS blade replaced a conventionally cast IN100 component; a 40% cost saving is expected, with a 2.4% reduction in the takeoff specific fuel consumption. The DS Mar-M 247 blade has been selected for production in the TFE731-3B-100, and advanced version of the TFE731-3.

Blade tip timing (BTT) uncertainties

NASA Astrophysics Data System (ADS)

Russhard, Pete

2016-06-01

Blade Tip Timing (BTT) is an alternative technique for characterising blade vibration in which non-contact timing probes (e.g. capacitance or optical probes), typically mounted on the engine casing (figure 1), and are used to measure the time at which a blade passes each probe. This time is compared with the time at which the blade would have passed the probe if it had been undergoing no vibration. For a number of years the aerospace industry has been sponsoring research into Blade Tip Timing technologies that have been developed as tools to obtain rotor blade tip deflections. These have been successful in demonstrating the potential of the technology, but rarely produced quantitative data, along with a demonstration of a traceable value for measurement uncertainty. BTT technologies have been developed under a cloak of secrecy by the gas turbine OEM's due to the competitive advantages it offered if it could be shown to work. BTT measurements are sensitive to many variables and there is a need to quantify the measurement uncertainty of the complete technology and to define a set of guidelines as to how BTT should be applied to different vehicles. The data shown in figure 2 was developed from US government sponsored program that bought together four different tip timing system and a gas turbine engine test. Comparisons showed that they were just capable of obtaining measurement within a +/-25% uncertainty band when compared to strain gauges even when using the same input data sets.

Flow structure generated by perpendicular blade-vortex interaction and implications for helicopter noise prediction. Volume 1: Measurements

NASA Technical Reports Server (NTRS)

Wittmer, Kenneth S.; Devenport, William J.

1996-01-01

The perpendicular interaction of a streamwise vortex with an infinite span helicopter blade was modeled experimentally in incompressible flow. Three-component velocity and turbulence measurements were made using a sub-miniature four sensor hot-wire probe. Vortex core parameters (radius, peak tangential velocity, circulation, and centerline axial velocity deficit) were determined as functions of blade-vortex separation, streamwise position, blade angle of attack, vortex strength, and vortex size. The downstream development of the flow shows that the interaction of the vortex with the blade wake is the primary cause of the changes in the core parameters. The blade sheds negative vorticity into its wake as a result of the induced angle of attack generated by the passing vortex. Instability in the vortex core due to its interaction with this negative vorticity region appears to be the catalyst for the magnification of the size and intensity of the turbulent flowfield downstream of the interaction. In general, the core radius increases while peak tangential velocity decreases with the effect being greater for smaller separations. These effects are largely independent of blade angle of attack; and if these parameters are normalized on their undisturbed values, then the effects of the vortex strength appear much weaker. Two theoretical models were developed to aid in extending the results to other flow conditions. An empirical model was developed for core parameter prediction which has some rudimentary physical basis, implying usefulness beyond a simple curve fit. An inviscid flow model was also created to estimate the vorticity shed by the interaction blade, and to predict the early stages of its incorporation into the interacting vortex.

The Development and Hover Test Application of a Projection Moire Interferometry Blade Displacement Measurement System

NASA Technical Reports Server (NTRS)

Sekula, Martin K.

2012-01-01

Projection moir interferometry (PMI) was employed to measure blade deflections during a hover test of a generic model-scale rotor in the NASA Langley 14x22 subsonic wind tunnel s hover facility. PMI was one of several optical measurement techniques tasked to acquire deflection and flow visualization data for a rotor at several distinct heights above a ground plane. Two of the main objectives of this test were to demonstrate that multiple optical measurement techniques can be used simultaneously to acquire data and to identify and address deficiencies in the techniques. Several PMI-specific technical challenges needed to be addressed during the test and in post-processing of the data. These challenges included developing an efficient and accurate calibration method for an extremely large (65 inch) height range; automating the analysis of the large amount of data acquired during the test; and developing a method to determinate the absolute displacement of rotor blades without a required anchor point measurement. The results indicate that the use of a single-camera/single-projector approach for the large height range reduced the accuracy of the PMI system compared to PMI systems designed for smaller height ranges. The lack of the anchor point measurement (due to a technical issue with one of the other measurement techniques) limited the ability of the PMI system to correctly measure blade displacements to only one of the three rotor heights tested. The new calibration technique reduced the data required by 80 percent while new post-processing algorithms successfully automated the process of locating rotor blades in images, determining the blade quarter chord location, and calculating the blade root and blade tip heights above the ground plane.

Hover and Wind-Tunnel Testing of Shrouded Rotors for Improved Micro Air Vehicle Design

DTIC Science & Technology

2008-01-01

and the shroud surface pressure distributions. The uniformity of the wake was improved by the presence of the shrouds and by decreasing the blade tip...213 3.35 Effect of blade tip clearance on shrouded-rotor exit-plane wake profiles215 3.36 Effects of changing blade tip clearance on induced...Wright [139] developed a vortex wake model for heavily loaded ducted fans, in which the “inner vortex sheets [shed from the blades ] move at a different

Forced response of mistuned bladed disk assemblies

NASA Technical Reports Server (NTRS)

Watson, Brian C.; Kamat, Manohar P.; Murthy, Durbha V.

1993-01-01

A complete analytic model of mistuned bladed disk assemblies, designed to simulate the dynamical behavior of these systems, is analyzed. The model incorporates a generalized method for describing the mistuning of the assembly through the introduction of specific mistuning modes. The model is used to develop a computational bladed disk assembly model for a series of parametric studies. Results are presented demonstrating that the response amplitudes of bladed disk assemblies depend both on the excitation mode and on the mistune mode.

New Tools Being Developed for Engine- Airframe Blade-Out Structural Simulations

NASA Technical Reports Server (NTRS)

Lawrence, Charles

2003-01-01

One of the primary concerns of aircraft structure designers is the accurate simulation of the blade-out event. This is required for the aircraft to pass Federal Aviation Administration (FAA) certification and to ensure that the aircraft is safe for operation. Typically, the most severe blade-out occurs when a first-stage fan blade in a high-bypass gas turbine engine is released. Structural loading results from both the impact of the blade onto the containment ring and the subsequent instantaneous unbalance of the rotating components. Reliable simulations of blade-out are required to ensure structural integrity during flight as well as to guarantee successful blade-out certification testing. The loads generated by these analyses are critical to the design teams for several components of the airplane structures including the engine, nacelle, strut, and wing, as well as the aircraft fuselage. Currently, a collection of simulation tools is used for aircraft structural design. Detailed high-fidelity simulation tools are used to capture the structural loads resulting from blade loss, and then these loads are used as input into an overall system model that includes complete structural models of both the engines and the airframe. The detailed simulation (shown in the figure) includes the time-dependent trajectory of the lost blade and its interactions with the containment structure, and the system simulation includes the lost blade loadings and the interactions between the rotating turbomachinery and the remaining aircraft structural components. General-purpose finite element structural analysis codes are typically used, and special provisions are made to include transient effects from the blade loss and rotational effects resulting from the engine s turbomachinery. To develop and validate these new tools with test data, the NASA Glenn Research Center has teamed with GE Aircraft Engines, Pratt & Whitney, Boeing Commercial Aircraft, Rolls-Royce, and MSC.Software.

Computer-Aided Design Of Turbine Blades And Vanes

NASA Technical Reports Server (NTRS)

Hsu, Wayne Q.

1988-01-01

Quasi-three-dimensional method for determining aerothermodynamic configuration of turbine uses computer-interactive analysis and design and computer-interactive graphics. Design procedure executed rapidly so designer easily repeats it to arrive at best performance, size, structural integrity, and engine life. Sequence of events in aerothermodynamic analysis and design starts with engine-balance equations and ends with boundary-layer analysis and viscous-flow calculations. Analysis-and-design procedure interactive and iterative throughout.

Development of a Highly Loaded Rotor Blade for Steam Turbines

NASA Astrophysics Data System (ADS)

Segawa, Kiyoshi; Shikano, Yoshio; Tsubouchi, Kuniyoshi; Shibashita, Naoaki

Turbine manufacturers have been concerned about efficient utilization of limited energy resources and prevention of environmental pollution. For steam turbine power plants, a higher efficiency gain is necessary to reduce the fuel consumption rate. Blade configurations have been studied for reductions of profile loss and endwall loss that lead to decreased steam turbine internal efficiency, by applying recent aerodynamic technologies based on advanced numerical analysis methods. This paper discusses increase of pitch-chord ratio by 14% (reduction of rotor blade numbers by 14%) and increased blade aerodynamic loading without deterioration of performance. A new rotor cascade is found which improves blade performance, especially at the root section where the reduction in the energy loss coefficient is about 40%. This rotor blade also provides lower manufacturing cost.

Blade Displacement Measurement Technique Applied to a Full-Scale Rotor Test

NASA Technical Reports Server (NTRS)

Abrego, Anita I.; Olson, Lawrence E.; Romander, Ethan A.; Barrows, Danny A.; Burner, Alpheus W.

2012-01-01

Blade displacement measurements using multi-camera photogrammetry were acquired during the full-scale wind tunnel test of the UH-60A Airloads rotor, conducted in the National Full-Scale Aerodynamics Complex 40- by 80-Foot Wind Tunnel. The objectives were to measure the blade displacement and deformation of the four rotor blades as they rotated through the entire rotor azimuth. These measurements are expected to provide a unique dataset to aid in the development and validation of rotorcraft prediction techniques. They are used to resolve the blade shape and position, including pitch, flap, lag and elastic deformation. Photogrammetric data encompass advance ratios from 0.15 to slowed rotor simulations of 1.0, thrust coefficient to rotor solidity ratios from 0.01 to 0.13, and rotor shaft angles from -10.0 to 8.0 degrees. An overview of the blade displacement measurement methodology and system development, descriptions of image processing, uncertainty considerations, preliminary results covering static and moderate advance ratio test conditions and future considerations are presented. Comparisons of experimental and computational results for a moderate advance ratio forward flight condition show good trend agreements, but also indicate significant mean discrepancies in lag and elastic twist. Blade displacement pitch measurements agree well with both the wind tunnel commanded and measured values.

Wind turbine generators with active radar signature control blades

NASA Astrophysics Data System (ADS)

Tennant, Alan; Chambers, Barry

2004-07-01

The large radar cross section of wind turbine generator (WTG) blades combined with high tip speeds can produce significant Doppler returns when illuminated by a radar. Normally, an air traffic control radar system will filter out large returns from stationary targets, however the Doppler shifts introduced by the WTG are interpreted as moving aircraft that can confuse radar operators and compromise safety. A possible solution to this problem that we are investigating is to incorporate an active layer into the structure of the WTG blades that can be used to dynamically modulate the RCS of the blade return. The active blade can operate in one of two modes: firstly the blade RCS can be modulated to provide a Doppler return that is outside the detectable range of the radar receiver system so that it is rejected: a second mode of operation is to introduce specific coding on to the Doppler returns so that they may be uniquely identified and rejected. The active layer used in the system consists of a frequency selective surface controlled by semiconductor diodes and is a development of techniques that we have developed for active radar absorbers. Results of experimental work using a 10GHz Doppler radar and scale model WTG with active Doppler imparting blades are presented.

Effect of Spindle Parameters of Woodworking Band Saw on the AE Value of Crack Band Saw Blade in Compound Material Processing (1)

NASA Astrophysics Data System (ADS)

Gao, Jin-gui; Jiang, Zhao-fang; Luo, Lai-peng

2017-04-01

Taking the MJ3210A motion band saw as the research object, the AE value of the band saw blade vibration was obtained by analyzing the VIBSYS vibration signal acquisition and analysis software system in Beijing, and the change of the AE value of the band saw and the crack was found out. The experimental results show that in the MJ3210A sports car sawing machine, the band saw blade with width of 130 mm is used, and the AE value of the cracked band saw blade is well in the high band saw blade AE value. Under the best working condition of the band saw, the band saw blade AE If the value exceeds 104.7 dB (A) above, it means that the band saw blade has at least one crack length greater than 1.38 mm for the crack defect and the need to replace the band saw blade in time. Different species with saw blade of the AE value is different, white pine wood minimum, the largest oak wood; according to a variety of wood processing AE instrument value to determine the band saw blade crack to the situation; so as to fully rational use of band saw blade, The failure and the degree of development to find a new method.

Feasibility study on a strain based deflection monitoring system for wind turbine blades

NASA Astrophysics Data System (ADS)

Lee, Kyunghyun; Aihara, Aya; Puntsagdash, Ganbayar; Kawaguchi, Takayuki; Sakamoto, Hiraku; Okuma, Masaaki

2017-01-01

The bending stiffness of the wind turbine blades has decreased due to the trend of wind turbine upsizing. Consequently, the risk of blades breakage by hitting the tower has increased. In order to prevent such incidents, this study proposes a deflection monitoring system that can be installed to already operating wind turbine's blades. The monitoring system is composed of an estimation algorithm to detect blade deflection and a wireless sensor network as a hardware equipment. As for the estimation method for blade deflection, a strain-based estimation algorithm and an objective function for optimal sensor arrangement are proposed. Strain-based estimation algorithm is using a linear correlation between strain and deflections, which can be expressed in a form of a transformation matrix. The objective function includes the terms of strain sensitivity and condition number of the transformation matrix between strain and deflection. In order to calculate the objective function, a simplified experimental model of the blade is constructed by interpolating the mode shape of a blade from modal testing. The interpolation method is effective considering a practical use to operating wind turbines' blades since it is not necessary to establish a finite element model of a blade. On the other hand, a sensor network with wireless connection with an open source hardware is developed. It is installed to a 300 W scale wind turbine and vibration of the blade on operation is investigated.

Blade system design studies volume II : preliminary blade designs and recommended test matrix.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Griffin, Dayton A.

2004-06-01

As part of the U.S. Department of Energy's Wind Partnerships for Advanced Component Technologies (WindPACT) program, Global Energy Concepts, LLC is performing a Blade System Design Study (BSDS) concerning innovations in materials, processes and structural configurations for application to wind turbine blades in the multi-megawatt range. The BSDS Volume I project report addresses issues and constraints identified to scaling conventional blade designs to the megawatt size range, and evaluated candidate materials, manufacturing and design innovations for overcoming and improving large blade economics. The current report (Volume II), presents additional discussion of materials and manufacturing issues for large blades, including amore » summary of current trends in commercial blade manufacturing. Specifications are then developed to guide the preliminary design of MW-scale blades. Using preliminary design calculations for a 3.0 MW blade, parametric analyses are performed to quantify the potential benefits in stiffness and decreased gravity loading by replacement of a baseline fiberglass spar with carbon-fiberglass hybrid material. Complete preliminary designs are then presented for 3.0 MW and 5.0 MW blades that incorporate fiberglass-to-carbon transitions at mid-span. Based on analysis of these designs, technical issues are identified and discussed. Finally, recommendations are made for composites testing under Part I1 of the BSDS, and the initial planned test matrix for that program is presented.« less

TADS: A CFD-based turbomachinery and analysis design system with GUI. Volume 1: Method and results

NASA Technical Reports Server (NTRS)

Topp, D. A.; Myers, R. A.; Delaney, R. A.

1995-01-01

The primary objective of this study was the development of a CFD (Computational Fluid Dynamics) based turbomachinery airfoil analysis and design system, controlled by a GUI (Graphical User Interface). The computer codes resulting from this effort are referred to as TADS (Turbomachinery Analysis and Design System). This document is the Final Report describing the theoretical basis and analytical results from the TADS system, developed under Task 18 of NASA Contract NAS3-25950, ADPAC System Coupling to Blade Analysis & Design System GUI. TADS couples a throughflow solver (ADPAC) with a quasi-3D blade-to-blade solver (RVCQ3D) in an interactive package. Throughflow analysis capability was developed in ADPAC through the addition of blade force and blockage terms to the governing equations. A GUI was developed to simplify user input and automate the many tasks required to perform turbomachinery analysis and design. The coupling of the various programs was done in such a way that alternative solvers or grid generators could be easily incorporated into the TADS framework. Results of aerodynamic calculations using the TADS system are presented for a highly loaded fan, a compressor stator, a low speed turbine blade and a transonic turbine vane.

Noninterference Systems Developed for Measuring and Monitoring Rotor Blade Vibrations

NASA Technical Reports Server (NTRS)

Kurkov, Anatole P.

2003-01-01

In the noninterference measurement of blade vibrations, a laser light beam is transmitted to the rotor blade tips through a single optical fiber, and the reflected light from the blade tips is collected by a receiving fiber-optic bundle and conducted to a photodetector. Transmitting and receiving fibers are integrated in an optical probe that is enclosed in a metal tube which also houses a miniature lens that focuses light on the blade tips. Vibratory blade amplitudes can be deduced from the measurement of the instantaneous time of arrival of the blades and the knowledge of the rotor speed. The in-house noninterference blade-vibration measurement system was developed in response to requirements to monitor blade vibrations in several tests where conventional strain gauges could not be installed or where there was a need to back up strain gauges should critical gauges fail during the test. These types of measurements are also performed in the aircraft engine industry using proprietary in-house technology. Two methods of measurement were developed for vibrations that are synchronous with a rotor shaft. One method requires only one sensor; however, it is necessary to continuously record the data while the rotor is being swept through the resonance. In the other method, typically four sensors are employed and the vibratory amplitude is deduced from the data by performing a least square fit to a harmonic function. This method does not require continuous recording of data through the resonance and, therefore, is better suited for monitoring. The single-probe method was tested in the Carl facility at the Wright- Patterson Air Force Base, and the multiple-probe method was tested in NASA Glenn Research Center's Spin Rig facility, which uses permanent magnets to excite synchronous vibrations. Representative results from this test are illustrated in the bar chart. Nonsynchronous vibrations were measured online during testing of the Quiet High Speed Fan in Glenn s 9- by 15-Foot Low-Speed Wind Tunnel. Three sensors were employed, enabling a reconstruction of the vibratory patterns at the leading and trailing edges at the tip span, as well as a determination of vibratory amplitudes for every blade.

Devices that Alter the Tip Vortex of a Rotor

NASA Technical Reports Server (NTRS)

McAlister, Kenneth W.; Tung, Chee; Heineck, James T.

2001-01-01

Small devices were attached near the tip of a hovering rotor blade 'in order to alter the structure and trajectory of the trailing vortex. Stereo particle image velocimetry (PIV) images were used to quantify the wake behind the rotor blade during the first revolution. A procedure for analyzing the 3D-velocity field is presented that includes a method for accounting for vortex wander. The results show that a vortex generator can alter the trajectory of the trailing vortex and that a major change in the size and intensity of the trailing vortex can be achieved by introducing a high level of turbulence into the core of the vortex.

The oil pressure test of the hydraulic impeller blade

NASA Astrophysics Data System (ADS)

Ye, Wen-bo; Jia, Li-tao

2017-12-01

This article introduced the structure of the Kaplan runner in hydropower station and the operating process of the oil pressure test has been described. What’s more, the whole process, including filling oil to the runner hub, the movement of the runner blade, the oil circuit, have been presented in detail.Since the manipulation of the oil circuit which controlled by three Valve groups consisting of six valves was complicated, the author is planning to replace them with 3-position 3-way electromagnetic valves, so we can simplify the operation procedure.The author hopes this article can provide technical reference for the oil pressure test.

NREL/University of Delaware Offshore Wind R&D Collaboration: Cooperative Research and Development Final Report, CRADA Number CRD-10-393

DOE Office of Scientific and Technical Information (OSTI.GOV)

Musial, Walt

2015-11-12

Specifically, the work under this CRADA includes, but is not limited to, the development of test procedures for an offshore test site in Delaware waters; testing of installed offshore wind turbines; performance monitoring of those turbines; and a program of research and development on offshore wind turbine blades, components, coatings, foundations, installation and construction of bottom-fixed structures, environmental impacts, policies, and more generally on means to enhance the reliability, facilitate permitting, and reduce costs for offshore wind turbines. This work will be conducted both at NREL's National Wind Technology Center and participant facilities, as well as the established offshore windmore » test sites.« less

Visualization of boundary-layer development on turbomachine blades with liquid crystals

NASA Technical Reports Server (NTRS)

Vanzante, Dale E.; Okiishi, Theodore H.

1991-01-01

This report documents a study of the use of liquid crystals to visualize boundary layer development on a turbomachine blade. A turbine blade model in a linear cascade of blades was used for the tests involved. Details of the boundary layer development on the suction surface of the turbine blade model were known from previous research. Temperature sensitive and shear sensitive liquid crystals were tried as visual agents. The temperature sensitive crystals were very effective in their ability to display the location of boundary layer flow separation and reattachment. Visualization of natural transition from laminar to turbulent boundary layer flow with the temperature sensitive crystals was possible but subtle. The visualization of separated flow reattachment with the shear sensitive crystals was easily accomplished when the crystals were allowed to make a transition from the focal-conic to a Grandjean texture. Visualization of flow reattachment based on the selective reflection properties of shear sensitive crystals was achieved only marginally because of the larger surface shear stress and shear stress gradient levels required for more dramatic color differences.

Turbulence Modeling and Computation of Turbine Aerodynamics and Heat Transfer

NASA Technical Reports Server (NTRS)

Lakshminarayana, B.; Luo, J.

1996-01-01

The objective of the present research is to develop improved turbulence models for the computation of complex flows through turbomachinery passages, including the effects of streamline curvature, heat transfer and secondary flows. Advanced turbulence models are crucial for accurate prediction of rocket engine flows, due to existance of very large extra strain rates, such as strong streamline curvature. Numerical simulation of the turbulent flows in strongly curved ducts, including two 180-deg ducts, one 90-deg duct and a strongly concave curved turbulent boundary layer have been carried out with Reynolds stress models (RSM) and algebraic Reynolds stress models (ARSM). An improved near-wall pressure-strain correlation has been developed for capturing the anisotropy of turbulence in the concave region. A comparative study of two modes of transition in gas turbine, the by-pass transition and the separation-induced transition, has been carried out with several representative low-Reynolds number (LRN) k-epsilon models. Effects of blade surface pressure gradient, freestream turbulence and Reynolds number on the blade boundary layer development, and particularly the inception of transition are examined in detail. The present study indicates that the turbine blade transition, in the presence of high freestream turbulence, is predicted well with LRN k-epsilon models employed. The three-dimensional Navier-Stokes procedure developed by the present authors has been used to compute the three-dimensional viscous flow through the turbine nozzle passage of a single stage turbine. A low Reynolds number k-epsilon model and a zonal k-epsilon/ARSM (algebraic Reynolds stress model) are utilized for turbulence closure. An assessment of the performance of the turbulence models has been carried out. The two models are found to provide similar predictions for the mean flow parameters, although slight improvement in the prediction of some secondary flow quantities has been obtained by the ARSM model. It's found that the wake profiles inside the endwall boundary layers are predicted better than those near the mid-span.

Design and initial testing of a one-bladed 30-meter-diameter rotor on the NASA/DOE mod-O wind turbine

NASA Technical Reports Server (NTRS)

Corrigan, R. D.; Ensworth, C. B. F.

1986-01-01

The concept of a one-bladed horizontal-axis wind turbine has been of interest to wind turbine designers for many years. Many designs and economic analyses of one-bladed wind turbines have been undertaken by both United States and European wind energy groups. The analyses indicate significant economic advantages but at the same time, significant dynamic response concerns. In an effort to develop a broad data base on wind turbine design and operations, the NASA Wind Energy Project Office has tested a one-bladed rotor at the NASA/DOE Mod-O Wind Turbine Facility. This is the only known test on an intermediate-sized one-bladed rotor in the United States. The 15.2-meter-radius rotor consists of a tip-controlled blade and a counterweight assembly. A rigorous test series was conducted in the Fall of 1985 to collect data on rotor performance, drive train/generator dynamics, structural dynamics, and structural loads. This report includes background information on one-bladed rotor concepts, and Mod-O one-bladed rotor test configuration, supporting design analysis, the Mod-O one-blade rotor test plan, and preliminary test results.

Ancient Technology in Contemporary Surgery

PubMed Central

Buck, Bruce A.

1982-01-01

Archaeologists have shown that ancient man developed the ability to produce cutting blades of an extreme degree of sharpness from volcanic glass. The finest of these prismatic blades were produced in Mesoamerica about 2,500 years ago. The technique of production of these blades was rediscovered 12 years ago by Dr. Don Crabtree, who suggested possible uses for the blades in modern surgery. Blades produced by Dr. Crabtree have been used in experimental microsurgery with excellent results. Animal experiments have shown the tensile strength of obsidian produced wounds to be equal to or greater than that of wounds produced by steel scalpels after 14 days of healing. We have been able to demonstrate neither flaking of glass blades into the wounds nor any foreign body reaction in healed wounds. Skin incisions in human patients have likewise healed well without complications. The prismatic glass blade is infinitely sharper than a honed steel edge, and these blades can be produced in a wide variety of shapes and sizes. It is therefore suggested that this type of blade may find an appropriate use in special areas of modern surgery. ImagesFigure 1.Figure 2.Figure 3. PMID:7046256

On the effect of moving blade grid on the flow field characteristics

NASA Astrophysics Data System (ADS)

Procházka, Pavel; Uruba, Václav; Pešek, Luděk; Bula, VÍtězslav

2018-06-01

The motivation of this paper is the continual development of the blades for the last stage of the steam turbine. The biggest problem is the slenderness of such blades and the extreme sensitivity to aeroelastic vibrations (flutter) caused by the instabilities present in the flow. This experimental research is dealing with the aeroelastic binding of the moving blades located in the blade grid with the flow field and vice versa. A parallelogram is used to ensure one order of freedom of the blade. The grid has five blades in total, three of them are driven by force control using three shakers. The deviation as well as force response is measured by strain gauges and dynamometers. The flow field statistical as well as dynamical characteristics are measured by optical method Particle Image Velocimetry. The grid is connected to the blow-down wind tunnel with velocity range up to 40 m/s. The aeroelastic binding is investigated in dependency on used actuation frequency and maximal amplitude (the intensity of force actuation) and on different Reynolds numbers. The flow field and the wake behind each individual blade are studied and the maximal interaction is examined for individual inter-blade phase angle of the grid.

A novel test rig to investigate under-platform damper dynamics

NASA Astrophysics Data System (ADS)

Botto, Daniele; Umer, Muhammad

2018-02-01

In the field of turbomachinery, vibration amplitude is often reduced by dissipating the kinetic energy of the blades with devices that utilize dry friction. Under-platform dampers, for example, are often placed in the underside of two consecutive turbine blades. Dampers are kept in contact with the under-platform of the respective blades by means of the centrifugal force. If the damper is well designed, vibration of blades instigate a relative motion between the under-platform and the damper. A friction force, that is a non-conservative force, arises in the contact and partly dissipates the vibration energy. Several contact models are available in the literature to simulate the contact between the damper and the under-platform. However, the actual dynamics of the blade-damper interaction have not fully understood yet. Several test rigs have been previously developed to experimentally investigate the performance of under-platform dampers. The majority of these experimental setups aim to evaluate the overall damper efficiency in terms of reduction in response amplitude of the blade for a given exciting force that simulates the aerodynamic loads. Unfortunately, the experimental data acquired on the blade dynamics do not provide enough information to understand the damper dynamics. Therefore, the uncertainty on the damper behavior remains a big issue. In this work, a novel experimental test rig has been developed to extensively investigate the damper dynamic behavior. A single replaceable blade is clamped in the rig with a specific clamping device. With this device the blade root is pressed against a groove machined in the test rig. The pushing force is controllable and measurable, to better simulate the actual centrifugal load acting on the blade. Two dampers, one on each side of the blade, are in contact with the blade under-platforms and with platforms on force measuring supports. These supports have been specifically designed to measure the contact forces on the damper. The contact forces on the blade are computed by post processing the measured forces and assuming the static equilibrium of the damper. The damper kinematics is rebuilt by using the relative displacement, measured with a differential laser, between the damper and the blade under-platform. This article describes the main concepts behind this new approach and explains the design and working of this novel test rig. Moreover, the influence of the damper contact forces on the dynamic behavior of the blade is discussed in the result section.

Bladed disc crack diagnostics using blade passage signals

NASA Astrophysics Data System (ADS)

Hanachi, Houman; Liu, Jie; Banerjee, Avisekh; Koul, Ashok; Liang, Ming; Alavi, Elham

2012-12-01

One of the major potential faults in a turbo fan engine is the crack initiation and propagation in bladed discs under cyclic loads that could result in the breakdown of the engines if not detected at an early stage. Reliable fault detection techniques are therefore in demand to reduce maintenance cost and prevent catastrophic failures. Although a number of approaches have been reported in the literature, it remains very challenging to develop a reliable technique to accurately estimate the health condition of a rotating bladed disc. Correspondingly, this paper presents a novel technique for bladed disc crack detection through two sequential signal processing stages: (1) signal preprocessing that aims to eliminate the noises in the blade passage signals; (2) signal postprocessing that intends to identify the crack location. In the first stage, physics-based modeling and interpretation are established to help characterize the noises. The crack initiation can be determined based on the calculated health monitoring index derived from the sinusoidal effects. In the second stage, the crack is located through advanced detrended fluctuation analysis of the preprocessed data. The proposed technique is validated using a set of spin rig test data (i.e. tip clearance and time of arrival) that was acquired during a test conducted on a bladed military engine fan disc. The test results have demonstrated that the developed technique is an effective approach for identifying and locating the incipient crack that occurs at the root of a bladed disc.

Review of status and potential of tungsten-wire: Superalloy composites for advanced gas turbine engine blades

NASA Technical Reports Server (NTRS)

Signorelli, R. A.

1972-01-01

The current status of development of refractory-wire-superalloy composites and the potential for their application to turbine blades in land-based power generation and advanced aircraft engines are reviewed. The data indicate that refractory-wire-superalloy composites have application as turbine blades at temperatures of 2200 F and above.

Alternative Fuels Data Center: Electricity Research and Development

Science.gov Websites

blades of a turbine connected to an electric generator. The turbine generator set converts mechanical and solar thermal, the heat that is produced is used to create steam, which moves the blades of the turbine. In the cases of hydropower and wind power, turbine blades are moved directly by flowing water and

Periodic acoustic radiation from a low aspect ratio propeller

NASA Astrophysics Data System (ADS)

Muench, John David

An experimental program was conducted with the objective of providing high fidelity measurements of propeller inflow, unsteady blade surface pressures, and discrete acoustic radiation over a wide range of speeds. Anechoic wind tunnel experiments were preformed using the SISUP propeller. The upstream stator blades generate large wake deficits that result in periodic unsteady blade forces that acoustically radiate at blade passing frequency and higher harmonics. The experimental portion of this research successfully measured the inflow velocity, blade span unsteady pressures and directive characteristics of the blade-rate radiated noise associated with this complex propeller geometry while the propeller was operating on design. The spatial harmonic decomposition of the inflow revealed significant coefficients at 8, 16 and 24. The magnitude of the unsteady blade forces scale as U4 and linearly shift in frequency with speed. The magnitude of the discrete frequency acoustic levels associated with blade rate scale as U6 and also shift linearly with speed. At blade-rate, the far-field acoustic directivity has a dipole-like directivity oriented perpendicular to the inflow. At the first harmonic of blade-rate, the far-field directivity is not as well defined. The experimental inflow and blade surface pressure results were used to generate an acoustic prediction at blade rate based on a blade strip theory model developed by Blake (1986). The predicted acoustic levels were compared to the experimental results. The model adequately predicts the measured sound field at blade rate at 120 ft/sec. Radiated noise at blade-rate for 120 ft/s can be described by a dipole, whose orientation is perpendicular to the flow and is generated by the interaction of the rotating propeller with the 8th harmonic of the inflow. At blade-rate for 60 ft/s, the model under predicts measured levels. At the first harmonic of blade-rate, for 120 ft/s, the sound field is described as a combination of dipole sources, one generated by the 16 th harmonic, perpendicular to the inflow, and the other generated by the 12th harmonic of the inflow parallel to the inflow. At the first harmonic of blade-rate for 60 ft/s, the model under predicts measured levels.

A method to estimate weight and dimensions of aircraft gas turbine engines. Volume 1: Method of analysis

NASA Technical Reports Server (NTRS)

Pera, R. J.; Onat, E.; Klees, G. W.; Tjonneland, E.

1977-01-01

Weight and envelope dimensions of aircraft gas turbine engines are estimated within plus or minus 5% to 10% using a computer method based on correlations of component weight and design features of 29 data base engines. Rotating components are estimated by a preliminary design procedure where blade geometry, operating conditions, material properties, shaft speed, hub-tip ratio, etc., are the primary independent variables used. The development and justification of the method selected, the various methods of analysis, the use of the program, and a description of the input/output data are discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rabin, B.H.

A simple modified tape casting procedure has been developed for application to ceramic joining when the joining materials are in powder form. The method involves preparation of a slurry from the powder, solvent, and thermoplastic binder, and then casting directly onto the joining surface using a moving doctor blade. Handling of the tape prior to joining is not necessary: therefore, binder content is minimized, plasticizers are not required, and viscosity is controlled by solvent content. The utility of this technique for producing joints with thin, uniform interlayers is demonstrated for silicon carbide materials joined with TiC + Ni and SiCmore » + Si.« less

Development of a wind energy converter with single blade rotor

NASA Astrophysics Data System (ADS)

Hipp, K.

1984-06-01

Wind energy converters with high tip speed ratio and a capacity of up to 50 kW in a 8.5 /msec wind speed were developed. Units with 12 m diameter rotors were tested. The concept of a cost favorable plant as a high speed engine with a supercritically running one blade rotor (soft bearing), gust balance out, automatic blade adjustment to ensure favorable starting qualities, proves to be a success. The single rectangular blade non-twisted with the profile NACA 23012/18 has no dynamic problems. The application of a centrifugal governor, i.e., vane like a Maxwell slat, operating only by rotation about a fixed hinge axis in order to attain adequate constant rotational speed of the plant, is not satisfactory.

High-power piezo drive amplifier for large stack and PFC applications

NASA Astrophysics Data System (ADS)

Clingman, Dan J.; Gamble, Mike

2001-08-01

This paper describes the continuing development of Boeing High Power Piezo Drive Amplifiers. Described is the development and testing of a 1500 Vpp, 8 amp switching amplifier. This amplifier is used to drive a piezo stack driven rotor blade trailing edge flap on a full size helicopter. Also discuss is a switching amplifier designed to drive a Piezo Fiber Composite (PFC) active twist rotor blade. This amplifier was designed to drive the PFC material at 2000 Vpp and 0.5 amps. These amplifiers recycle reactive energy, allowing for a power and weight efficient amplifier design. This work was done in conjunction with the DARPA sponsored Phase II Smart Rotor Blade program and the NASA Langley Research Center sponsored Active Twist Rotor (ATR) blade program.

Steady and unsteady blade stresses within the SSME ATD/HPOTP inducer

NASA Technical Reports Server (NTRS)

Gross, R. Steven

1994-01-01

There were two main goals of the ATD HPOTP (alternate turbopump development)(high pressure oxygen turbopump). First, determine the steady and unsteady inducer blade surface strains produced by hydrodynamic sources as a function of flow capacity (Q/N), suction specific speed (Nss), and Reynolds number (Re). Second, to identify the hydrodynamic source(s) of the unsteady blade strains. The reason the aforementioned goals are expressed in terms of blade strains as opposed to blade hydrodynamic pressures is because of the interest regarding the high cycle life of the inducer blades. This report focuses on the first goal of the test program which involves the determination of the steady and unsteady strain (stress) values at various points within the inducer blades. Strain gages were selected as the strain measuring devices. Concurrent with the experimental program, an analytical study was undertaken to produce a complete NASTRAN finite-element model of the inducer. Computational fluid dynamics analyses were utilized to provide the estimated steady-state blade surface pressure loading needed as load input to the NASTRAN inducer model.

International Symposium on Wind Energy Systems, 4th, Stockholm, Sweden, September 21-24, 1982, Proceedings. Volumes 1 & 2

NASA Astrophysics Data System (ADS)

Stephens, H. S.; Goodes, D. H.

Progress in theoretical, meteorological, and hardware development sectors of wind energy utilization is assessed for various national programs. Wind regime characterization studies in Agentina, China, Indonesia, Norway, the U.S., Canada, Sweden, Hawaii, and offshore of the U.K. are reported. Data gained from wind turbine test sites in the U.S., Denmark, Holland, Germany, and the Netherlands are outlined. Attention is focused on the economics of wind turbine production for utility, agricultural, and third party purposes, with mention made of utilizing the resource appropriately for areas of installation of the wind powered machinery. Analyses are made of diurnal wind variations compared to diurnal demands on conventinal electricity generating power stations. Performance projections are made for wind farms featuring multi-MW machines, taking into account grid inteconnection factors, electrical control, power ramps, and environmental considerations. Mention is made of aeroelastics, dynamics, and the aerodynamics of wind turbines and rotor blades. Finally, icing, noise, fatigue failure, and blade throw problem are discussed, together with wind turbine licensing procedures in Denmark. No invidivual items are abstracted in these volumes

Strength and dynamic characteristics analyses of wound composite axial impeller

NASA Astrophysics Data System (ADS)

Wang, Jifeng; Olortegui-Yume, Jorge; Müller, Norbert

2012-03-01

A low cost, light weight, high performance composite material turbomachinery impeller with a uniquely designed blade patterns is analyzed. Such impellers can economically enable refrigeration plants to use water as a refrigerant (R718). A strength and dynamic characteristics analyses procedure is developed to assess the maximum stresses and natural frequencies of these wound composite axial impellers under operating loading conditions. Numerical simulation using FEM for two-dimensional and three-dimensional impellers was investigated. A commercially available software ANSYS is used for the finite element calculations. Analysis is done for different blade geometries and then suggestions are made for optimum design parameters. In order to avoid operating at resonance, which can make impellers suffer a significant reduction in the design life, the designer must calculate the natural frequency and modal shape of the impeller to analyze the dynamic characteristics. The results show that using composite Kevlar fiber/epoxy matrix enables the impeller to run at high tip speed and withstand the stresses, no critical speed will be matched during start-up and shut-down, and that mass imbalances of the impeller shall not pose a critical problem.

Real-time simulator for helicopter rotor wind-tunnel operations

NASA Technical Reports Server (NTRS)

Talbot, P. D.; Peterson, R. L.; Graham, D. R.

1986-01-01

This paper describes the elements and operation of a simulator that is being used to train operators of the Rotor Test Apparatus (RTA) in the large-scale 40- by 80-Foot Wind Tunnel at Ames Research Center. The simulator, named TUTOR (for Tunnel Utilization Trainer with Operating Rotor) duplicates the controls of the rotor and its dynamic behavior, as well as the wind-tunnel controls. The simulation software uses a preexisting blade-element model of a four-bladed rotor with flapping and lead-lag degrees of freedom. Equations were developed for all hardware and controls of the RTA and of the wind tunnel that are normally required to perform a wind-tunnel test of a helicopter rotor. The simulator hardware consists of consoles designed to have the same appearance and functions as those in the control room of the 40- by 80-Foot Wind Tunnel, allowing input from three operators who normally establish the required operating conditions during a test run. Normal operating procedures can be practiced, as well as simulated emergencies such as rotor power failure.

Wireless Sensors for Wind Turbine Blades Monitoring

NASA Astrophysics Data System (ADS)

Iftimie, N.; Steigmann, R.; Danila, N. A.; Rosu, D.; Barsanescu, P. D.; Savin, A.

2017-06-01

The most common defects in turbine blades may be faulty microscopic and mesoscopic appeared in matrix, no detected by classical nondestructive testing (i.e. using phased array sensors), broken fibers can also appear and develop under moderated loads, or cracks and delaminations due to low energy impacts, etc. The paper propose to present the results obtained from testing of glass fiber reinforced plastic used in the construction of the wind turbine blades as well as the monitoring of the entire scalable blade using wireless sensors placed on critical location on blade. In order to monitories the strain/stress during the tests, the determination of the location and the nature of defects have been simulated using FEM.

Paths of Improving the Technological Process of Manufacture of GTE Turbine Blades

NASA Astrophysics Data System (ADS)

Vdovin, R. A.; Smelov, V. G.; Bolotov, M. A.; Pronichev, N. D.

2016-08-01

The article provides an analysis of the problems at manufacture of blades of the turbine of gas-turbine engines and power stations is provided in article, and also paths of perfecting of technological process of manufacture of blades are offered. The analysis of the main systems of basing of blades in the course of machining and the control methods of the processed blades existing at the enterprises with the indication of merits and demerits is carried out. In work criteria in the form of the mathematical models of a spatial distribution of an allowance considering the uniform distribution of an allowance on a feather profile are developed. The considered methods allow to reduce percent of release of marriage and to reduce labor input when polishing path part of a feather of blades of the turbine.

Quasi-three-dimensional flow solution by meridional plane analysis

NASA Technical Reports Server (NTRS)

Katsanis, T.; Mcnally, W. D.

1974-01-01

A computer program has been developed to obtain subsonic or shockfree transonic, nonviscous flow analysis on the hub-shroud mid-channel flow surface of a turbomachine. The analysis may be for any annular passage, with or without blades. The blades may be fixed or rotating and may be twisted and leaned. The flow may be axial, radial or mixed. Blade surface velocities over the entire blade are approximated based on the rate of change of angular momentum. This gives a 3-D flow picture based on a 2-D analysis. The paper discusses the method used for the program and shows examples of the type of passages and blade rows which can be analyzed. Also, some numerical examples are given to show how the program can be used for practical assistance in design of blading, annular passages, and annular diffusers.

Noise from propellers with symmetrical sections at zero blade angle, II

NASA Technical Reports Server (NTRS)

Deming, A F

1938-01-01

In a previous paper (Technical Note No. 605), a theory was developed that required an empirical relation to calculate sound pressures for the higher harmonics. Further investigation indicated that the modified theory agrees with experiment and that the empirical relation was due to an interference phenomenon peculiar to the test arrangement used. Comparison is made between the test results for a two-blade arrangement and the theory. The comparison is made for sound pressures in the plane of the revolving blades for varying values of tip velocity. Comparison is also made at constant tip velocity for all values of azimuth angle B. A further check is made between the theory and the experimental results for the fundamental of a four-blade arrangement with blades of the same dimensions as those used in the two-blade arrangement.

Aerodynamic Measurements of an Incidence Tolerant Blade in a Transonic Turbine Cascade

NASA Technical Reports Server (NTRS)

McVetta, Ashlie B.; Giel, Paul W.

2012-01-01

An overview of the recent facility modifications to NASA s Transonic Turbine Blade Cascade Facility and aerodynamic measurements on the VSPT incidence-tolerant blade are presented. This work supports the development of variable-speed power turbine (VSPT) speed-change technology for the NASA Large Civil Tilt Rotor (LCTR) vehicle. In order to maintain acceptable main rotor propulsive efficiency, the VSPT operates over a nearly 50% speed range from takeoff to altitude cruise. This results in 50 or more variations in VSPT blade incidence angles. The Transonic Turbine Blade Cascade Facility has the ability to operate over a wide range of Reynolds numbers and Mach numbers, but had to be modified in order to accommodate the negative incidence angle variation required by the LCTR VSPT operation. Details of the modifications are described. An incidence-tolerant blade was developed under an RTPAS study contract and tested in the cascade to look at the effects of large incidence angle and Reynolds number variations. Recent test results are presented which include midspan exit total pressure and flow angle measurements obtained at three inlet angles representing the cruise, take-off, and maximum incidence flight mission points. For each inlet angle, data were obtained at five flow conditions with exit Reynolds numbers varying from 2.12 106 to 2.12 105 and two isentropic exit Mach numbers of 0.72 and 0.35. Three-dimensional flowfield measurements were also acquired at the cruise and take-off points. The flowfield measurements were acquired using a five-hole and three-hole pneumatic probe located in a survey plane 8.6% axial chord downstream of the blade trailing edge plane and covering three blade passages. Blade and endwall static pressure distributions were also acquired for each flow condition.

Mathematical support for automated geometry analysis of lathe machining of oblique peakless round-nose tools

NASA Astrophysics Data System (ADS)

Filippov, A. V.; Tarasov, S. Yu; Podgornyh, O. A.; Shamarin, N. N.; Filippova, E. O.

2017-01-01

Automatization of engineering processes requires developing relevant mathematical support and a computer software. Analysis of metal cutting kinematics and tool geometry is a necessary key task at the preproduction stage. This paper is focused on developing a procedure for determining the geometry of oblique peakless round-nose tool lathe machining with the use of vector/matrix transformations. Such an approach allows integration into modern mathematical software packages in distinction to the traditional analytic description. Such an advantage is very promising for developing automated control of the preproduction process. A kinematic criterion for the applicable tool geometry has been developed from the results of this study. The effect of tool blade inclination and curvature on the geometry-dependent process parameters was evaluated.

Fluid-structure interaction modeling of wind turbines: simulating the full machine

NASA Astrophysics Data System (ADS)

Hsu, Ming-Chen; Bazilevs, Yuri

2012-12-01

In this paper we present our aerodynamics and fluid-structure interaction (FSI) computational techniques that enable dynamic, fully coupled, 3D FSI simulation of wind turbines at full scale, and in the presence of the nacelle and tower (i.e., simulation of the "full machine"). For the interaction of wind and flexible blades we employ a nonmatching interface discretization approach, where the aerodynamics is computed using a low-order finite-element-based ALE-VMS technique, while the rotor blades are modeled as thin composite shells discretized using NURBS-based isogeometric analysis (IGA). We find that coupling FEM and IGA in this manner gives a good combination of efficiency, accuracy, and flexibility of the computational procedures for wind turbine FSI. The interaction between the rotor and tower is handled using a non-overlapping sliding-interface approach, where both moving- and stationary-domain formulations of aerodynamics are employed. At the fluid-structure and sliding interfaces, the kinematic and traction continuity is enforced weakly, which is a key ingredient of the proposed numerical methodology. We present several simulations of a three-blade 5~MW wind turbine, with and without the tower. We find that, in the case of no tower, the presence of the sliding interface has no effect on the prediction of aerodynamic loads on the rotor. From this we conclude that weak enforcement of the kinematics gives just as accurate results as the strong enforcement, and thus enables the simulation of rotor-tower interaction (as well as other applications involving mechanical components in relative motion). We also find that the blade passing the tower produces a 10-12 % drop (per blade) in the aerodynamic torque. We feel this finding may be important when it comes to the fatigue-life analysis and prediction for wind turbine blades.

Flow range enhancement by secondary flow effect in low solidity circular cascade diffusers

NASA Astrophysics Data System (ADS)

Sakaguchi, Daisaku; Tun, Min Thaw; Mizokoshi, Kanata; Kishikawa, Daiki

2014-08-01

High-pressure ratio and wide operating range are highly required for compressors and blowers. The technical issue of the design is achievement of suppression of flow separation at small flow rate without deteriorating the efficiency at design flow rate. A numerical simulation is very effective in design procedure, however, cost of the numerical simulation is generally high during the practical design process, and it is difficult to confirm the optimal design which is combined with many parameters. A multi-objective optimization technique is the idea that has been proposed for solving the problem in practical design process. In this study, a Low Solidity circular cascade Diffuser (LSD) in a centrifugal blower is successfully designed by means of multi-objective optimization technique. An optimization code with a meta-model assisted evolutionary algorithm is used with a commercial CFD code ANSYS-CFX. The optimization is aiming at improving the static pressure coefficient at design point and at low flow rate condition while constraining the slope of the lift coefficient curve. Moreover, a small tip clearance of the LSD blade was applied in order to activate and to stabilize the secondary flow effect at small flow rate condition. The optimized LSD blade has an extended operating range of 114 % towards smaller flow rate as compared to the baseline design without deteriorating the diffuser pressure recovery at design point. The diffuser pressure rise and operating flow range of the optimized LSD blade are experimentally verified by overall performance test. The detailed flow in the diffuser is also confirmed by means of a Particle Image Velocimeter. Secondary flow is clearly captured by PIV and it spreads to the whole area of LSD blade pitch. It is found that the optimized LSD blade shows good improvement of the blade loading in the whole operating range, while at small flow rate the flow separation on the LSD blade has been successfully suppressed by the secondary flow effect.

Percutaneous release of the plantar fascia. New surgical procedure.

PubMed

Oliva, Francesco; Piccirilli, Eleonora; Tarantino, Umberto; Maffulli, Nicola

2017-01-01

Plantar fasciopathy presents with pain at the plantar and medial aspect of the heel. If chronic, it can negatively impact on quality of life. Plantar fasciopathy is not always self-limiting, and can be debilitating. Surgical management involves different procedures. We describe a percutaneous plantar fascia release. A minimally invasive access to the plantar tuberosity of the calcaneus is performed, and a small scalpel blade is used to release the fascia. With this procedure, skin healing problems, nerve injuries, infection and prolonged recovery time are minimised, allowing early return to normal activities. V.

Ionisation induced collapse of minihaloes

NASA Astrophysics Data System (ADS)

Back, Trevor

2013-08-01

In order to analyse the turbine blade life, the damage due to the combined thermal and mechanical loads should be adequately accounted for. This is more challenging when detailed component geometry is limited. Therefore, a compromise between the level of geometric detail and the complexity of the lifing method to be implemented would be necessary. This research focuses on how the life assessment of aero engine turbine blades can be done, considering the balance between available design inputs and adequate level of fidelity. Accordingly, the thesis contributes to developing a generic turbine blade lifing method that is based on the engine thermodynamic cycle; as well as integrating critical design/technological factors and operational parameters that influence the aero engine blade life. To this end, thermo-mechanical fatigue was identified as the critical damage phenomenon driving the life of the turbine blade.. The developed approach integrates software tools and numerical models created using the minimum design information typically available at the early design stages. Using finite element analysis of an idealised blade geometry, the approach captures relevant impacts of thermal gradients and thermal stresses that contribute to the thermo-mechanical fatigue damage on the gas turbine blade. The blade life is evaluated using the Neu/Sehitoglu thermo-mechanical fatigue model that considers damage accumulation due to fatigue, oxidation, and creep. The leading edge is examined as a critical part of the blade to estimate the damage severity for different design factors and operational parameters. The outputs of the research can be used to better understand how the environment and the operating conditions of the aircraft affect the blade life consumption and therefore what is the impact on the maintenance cost and the availability of the propulsion system. This research also finds that the environmental (oxidation) effect drives the blade life and the blade coolant side was the critical location. Furthermore, a parametric and sensitivity study of the Neu/Sehitoglu model parameters suggests that in addition to four previously reported parameters, the sensitivity of the phasing to oxidation damage would be critical to overall blade life..

Numerical assessment of wind turbine blade damage due to contact/impact with tower during installation

NASA Astrophysics Data System (ADS)

Shankar Verma, Amrit; Petter Vedvik, Nils; Gao, Zhen

2017-12-01

The use of floating crane vessel for installation of offshore wind turbine blades presents a great challenge in terms of its random motions and is likely to increase the probability of the blade hitting the preassembled tower during lifting operation. To evaluate the consequences of such scenarios and to determine the allowable motions or sea states for such operations, it is very important to understand the damage development in the blade due to impact. The present paper employs the application of high fidelity finite element method to investigate the damage behavior in the blade when the leading edge of the blade hits the tower. A nonlinear time domain structural analysis using ABAQUS was conducted on the DTU 10 MW reference blade model which is based on shell elements. Damage assessment along with the nature of evolution of various energies is examined and presented for two different impact velocities with modified layup stacking sequence at the contact region.

Wind turbine blade shear web disbond detection using rotor blade operational sensing and data analysis.

PubMed

Myrent, Noah; Adams, Douglas E; Griffith, D Todd

2015-02-28

A wind turbine blade's structural dynamic response is simulated and analysed with the goal of characterizing the presence and severity of a shear web disbond. Computer models of a 5 MW offshore utility-scale wind turbine were created to develop effective algorithms for detecting such damage. Through data analysis and with the use of blade measurements, a shear web disbond was quantified according to its length. An aerodynamic sensitivity study was conducted to ensure robustness of the detection algorithms. In all analyses, the blade's flap-wise acceleration and root-pitching moment were the clearest indicators of the presence and severity of a shear web disbond. A combination of blade and non-blade measurements was formulated into a final algorithm for the detection and quantification of the disbond. The probability of detection was 100% for the optimized wind speed ranges in laminar, 30% horizontal shear and 60% horizontal shear conditions. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Hover Testing of the NASA/Army/MIT Active Twist Rotor Prototype Blade

NASA Technical Reports Server (NTRS)

Wilbur, Matthew L.; Yeager, William T., Jr.; Wilkie, W. Keats; Cesnik, Carlos E. S.; Shin, Sangloon

2000-01-01

Helicopter rotor individual blade control promises to provide a mechanism for increased rotor performance and reduced rotorcraft vibrations and noise. Active material methods, such as piezoelectrically actuated trailing-edge flaps and strain-induced rotor blade twisting, provide a means of accomplishing individual blade control without the need for hydraulic power in the rotating system. Recent studies have indicated that controlled strain induced blade twisting can be attained using piezoelectric active fiber composite technology. In order to validate these findings experimentally, a cooperative effort between NASA Langley Research Center, the Army Research Laboratory, and the MIT Active Materials and Structures Laboratory has been developed. As a result of this collaboration an aeroelastically-scaled active-twist model rotor blade has been designed and fabricated for testing in the heavy gas environment of the Langley Transonic Dynamics Tunnel (TDT). The results of hover tests of the active-twist prototype blade are presented in this paper. Comparisons with applicable analytical predictions of active-twist frequency response in hovering flight are also presented.

Examination, evaluation and repair of laminated wood blades after service on the Mod-OA wind turbine

NASA Technical Reports Server (NTRS)

Faddoul, J. R.

1983-01-01

Laminated wood blades were designed, fabricated, and installed on a 200-KW wind turbine (Mod-OA). The machine uses a two-blade rotor with a diameter of 38.1 m (125 ft). Each blade weights less than 1361 kg (3000 lb). After operating in the field, two blade sets were returned for inspection. One set had been in Hawaii for 17 months (7844 hr of operation) and the other had been at Block Island, Rhode Island, for 26 months (22 months operating - 7564 hr). The Hawaii set was returned because of one of the studs that holds the blade to the hub had failed. This was found to be caused by a combination of improper installation and inadequate corrosion protection. No other problems were found. The broken stud (along with four others that were badly corroded) was replaced and the blades are now in storage. The Block Island set of blades was returned at the completion of the test program, but one blade was found to have developed a crack in the leading edge along the entire span. This crack was found to be the result of a manufacturing process problem but was not structurally critical. When a load-deflection test was conducted on the cracked blade, the response was identical to that measured before installation. In general, the laminate quality of both blade sets was excellent. No significant internal delamination or structural defects were found in any blade. The stud bonding process requires close tolerance control and adequate corrosion protection, but studs can be removed and replaced without major problems. Moisture content stabilization does not appear to be a problem, and laminated wood blades are satisfactory for long-term operation on Mod-OA wind turbines.

Development and Validation of a New Blade Element Momentum Skewed-Wake Model within AeroDyn: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ning, S. A.; Hayman, G.; Damiani, R.

Blade element momentum methods, though conceptually simple, are highly useful for analyzing wind turbines aerodynamics and are widely used in many design and analysis applications. A new version of AeroDyn is being developed to take advantage of new robust solution methodologies, conform to a new modularization framework for National Renewable Energy Laboratory's FAST, utilize advanced skewed-wake analysis methods, fix limitations with previous implementations, and to enable modeling of highly flexible and nonstraight blades. This paper reviews blade element momentum theory and several of the options available for analyzing skewed inflow. AeroDyn implementation details are described for the benefit of usersmore » and developers. These new options are compared to solutions from the previous version of AeroDyn and to experimental data. Finally, recommendations are given on how one might select from the various available solution approaches.« less

Modeling methods for high-fidelity rotorcraft flight mechanics simulation

NASA Technical Reports Server (NTRS)

Mansur, M. Hossein; Tischler, Mark B.; Chaimovich, Menahem; Rosen, Aviv; Rand, Omri

1992-01-01

The cooperative effort being carried out under the agreements of the United States-Israel Memorandum of Understanding is discussed. Two different models of the AH-64 Apache Helicopter, which may differ in their approach to modeling the main rotor, are presented. The first model, the Blade Element Model for the Apache (BEMAP), was developed at Ames Research Center, and is the only model of the Apache to employ a direct blade element approach to calculating the coupled flap-lag motion of the blades and the rotor force and moment. The second model was developed at the Technion-Israel Institute of Technology and uses an harmonic approach to analyze the rotor. The approach allows two different levels of approximation, ranging from the 'first harmonic' (similar to a tip-path-plane model) to 'complete high harmonics' (comparable to a blade element approach). The development of the two models is outlined and the two are compared using available flight test data.

Active Vibration Reduction of Titanium Alloy Fan Blades (FAN1) Using Piezoelectric Materials

NASA Technical Reports Server (NTRS)

Choi, Benjamin; Kauffman, Jeffrey; Duffy, Kirsten; Provenza, Andrew; Morrison, Carlos

2010-01-01

The NASA Glenn Research Center is developing smart adaptive structures to improve fan blade damping at resonances using piezoelectric (PE) transducers. In this paper, a digital resonant control technique emulating passive shunt circuits is used to demonstrate vibration reduction of FAN1 Ti real fan blade at the several target modes. Single-mode control and multi-mode control using one piezoelectric material are demonstrated. Also a conceptual study of how to implement this digital control system into the rotating fan blade is discussed.

Preliminary design study of advanced composite blade and hub and nonmechanical control system for the tilt-rotor aircraft. Volume 1: Engineering studies

NASA Technical Reports Server (NTRS)

Alexander, H. R.; Smith, K. E.; Mcveigh, M. A.; Dixon, P. G.; Mcmanus, B. L.

1979-01-01

Composite structures technology is applied in a preliminary design study of advanced technology blades and hubs for the XV-15 tilt rotor research demonstrator aircraft. Significant improvements in XV-15 hover and cruise performance are available using blades designed for compatibility with the existing aircraft, i.e., blade installation would not require modification of the airframe, hub or upper controls. Provision of a low risk nonmechanical control system was also studied, and a development specification is given.

Impact of current speed on mass flux to a model flexible seagrass blade

NASA Astrophysics Data System (ADS)

Lei, Jiarui; Nepf, Heidi

2016-07-01

Seagrass and other freshwater macrophytes can acquire nutrients from surrounding water through their blades. This flux may depend on the current speed (U), which can influence both the posture of flexible blades (reconfiguration) and the thickness of the flux-limiting diffusive layer. The impact of current speed (U) on mass flux to flexible blades of model seagrass was studied through a combination of laboratory flume experiments, numerical modeling and theory. Model seagrass blades were constructed from low-density polyethylene (LDPE), and 1, 2-dichlorobenzene was used as a tracer chemical. The tracer mass accumulation in the blades was measured at different unidirectional current speeds. A numerical model was used to estimate the transfer velocity (K) by fitting the measured mass uptake to a one-dimensional diffusion model. The measured transfer velocity was compared to predictions based on laminar and turbulent boundary layers developing over a flat plate parallel to flow, for which K∝U0.5 and ∝U, respectively. The degree of blade reconfiguration depended on the dimensionless Cauchy number, Ca, which is a function of both the blade stiffness and flow velocity. For large Ca, the majority of the blade was parallel to the flow, and the measured transfer velocity agreed with laminar boundary layer theory, K∝U0.5. For small Ca, the model blades remained upright, and the flux to the blade was diminished relative to the flat-plate model. A meadow-scale analysis suggests that the mass exchange at the blade scale may control the uptake at the meadow scale.

Solution of the Average-Passage Equations for the Incompressible Flow through Multiple-Blade-Row Turbomachinery

DTIC Science & Technology

1994-02-01

numerical treatment. An explicit numerical procedure based on Runqe-Kutta time stepping for cell-centered, hexahedral finite volumes is...An explicit numerical procedure based on Runge-Kutta time stepping for cell-centered, hexahedral finite volumes is outlined for the approximate...Discretization 16 3.1 Cell-Centered Finite -Volume Discretization in Space 16 3.2 Artificial Dissipation 17 3.3 Time Integration 21 3.4 Convergence

Effectiveness enhancement of a cycloidal wind turbine by individual active control of blade motion

NASA Astrophysics Data System (ADS)

Hwang, In Seong; Lee, Yun Han; Kim, Seung Jo

2007-04-01

In this paper, a research for the effectiveness enhancement of a Cycloidal Wind Turbine by individual active control of blade motion is described. To improve the performance of the power generation system, which consists of several straight blades rotating about axis in parallel direction, the cycloidal blade system and the individual active blade control method are adopted. It has advantages comparing with horizontal axis wind turbine or conventional vertical axis wind turbine because it maintains optimal blade pitch angles according to wind speed, wind direction and rotor rotating speed to produce high electric power at any conditions. It can do self-starting and shows good efficiency at low wind speed and complex wind condition. Optimal blade pitch angle paths are obtained through CFD analysis according to rotor rotating speed and wind speed. The individual rotor blade control system consists of sensors, actuators and microcontroller. To realize the actuating device, servo motors are installed to each rotor blade. Actuating speed and actuating force are calculated to compare with the capacities of servo motor, and some delays of blade pitch angles are corrected experimentally. Performance experiment is carried out by the wind blowing equipment and Labview system, and the rotor rotates from 50 to 100 rpm according to the electric load. From this research, it is concluded that developing new vertical axis wind turbine, Cycloidal Wind Turbine which is adopting individual active blade pitch control method can be a good model for small wind turbine in urban environment.

Research on the nonintrusive measurement of the turbine blade vibration

NASA Astrophysics Data System (ADS)

Zhang, Shi hai; Li, Lu-ping; Rao, Hong-de

2008-11-01

It's one of the important ways to monitor the change of dynamic characteristic of turbine blades for ensuring safety operation of turbine unit. Traditional measurement systems for monitoring blade vibration generally use strain gauges attached to the surface of turbine blades, each strain gauge gives out an analogue signal related to blade deformation, it's maximal defect is only a few blades could be monitored which are attached by strain gauge. But the noncontact vibration measurement will be discussed would solve this problem. This paper deals with noncontact vibration measurement on the rotor blades of turbine through experiments. In this paper, the noncontact vibration measurement - Tip Timing Measurement will be presented, and will be improved. The statistics and DFT will be used in the improved measurement. The main advantage of the improved measurement is that only two sensors over the top of blades and one synchronous sensor of the rotor are used to get the exact vibration characteristics of the each blade in a row. In our experiment, we adopt NI Company's DAQ equipment: SCXI1001 and PCI 6221, three optical sensors, base on the graphics program soft LabVIEW to develop the turbine blade monitor system. At the different rotational speed of the rotor (1000r/m and 1200r/m) we do several experiments on the bench of the Turbine characteristic. Its results indicated that the vibration of turbine blade could be real-time monitored and accurately measured by the improved Tip Timing Measurement.

Double Intracavernous Breakage of Sachse's Knife Blade: Management of a Rare Complication Performing Direct Vision Internal Urethrotomy.

PubMed

Benincasa, Alfonso; Saita, Alberto; Pinto, Angelo; Pilerci, Carmine; Francesco, Lamberti; Russo, Aniello; Benincasa, Giuseppe

2017-01-01

Background: Although the breakage of a Sachse's knife blade is already a rare event while performing optical internal urethrotomy, a double failure appears to be at the same time a unique and a challenging complication to manage since no reference has emerged from literature review. Case Presentation: A male patient, 80 years of age, underwent retreatment of recurrent urethral stricture that occurred after transurethral resection of the prostate. The latter was complicated by severe intraoperative urethrorrhagia; this is the reason he was transferred from another institution where at first a suprapubic cystostomy was carried out, followed by urethral recanalization through internal urethrotomy and finally he underwent intracavernous Sachse's knife blade discharge. Preoperative evaluation included combined retrograde and voiding urethrography and CT to evaluate the complete resolution of the urethral stenosis and to establish the correct location of the blades inside the corpus cavernosum. A transperineal approach to the left corpus cavernosum was carried out with manageable removal of the foreign body and postoperative assessment showed no early considerable complications for the patient. Conclusion: To our knowledge, this is the first case of double breakage of Sachse's knife blade performing optical internal urethrotomy reported in literature. Although it may appear to be an easy procedure, close attention to its execution must always be paid to prevent major complications. A transperineal approach has proven to be effective and safe without creating any further outcomes to the patient.

Chem-Braze Abradable Seal Attachment

DTIC Science & Technology

1980-05-01

bonding system for attaching sintered abradable seals such as FELTMETAL® to titanium -, steel- and nickel-base compressor blade tip-shrouds has been... blade tip-shrouds was developed. The improved Chem-Braze system incorporates glycerin as an inhibitor to prevent premature evaporation which prolongs...compressor blade tip-shrouds using the improved Chem-Braze system compared to attachment with gold-nickel braze. p. p. FORM . . yn

Differential analysis for the turbulent boundary layer on a compressor blade element (including boundary-layer separation)

NASA Technical Reports Server (NTRS)

Schmidt, J. F.; Todd, C. A.

1974-01-01

A two-dimensional differential analysis is developed to approximate the turbulent boundary layer on a compressor blade element with strong adverse pressure gradients, including the separated region with reverse flow. The predicted turbulent boundary layer thicknesses and velocity profiles are in good agreement with experimental data for a cascade blade, even in the separated region.

Flutter of Darrieus wind turbine blades

NASA Technical Reports Server (NTRS)

Ham, N. D.

1978-01-01

The testing of Darrieus wind turbines has indicated that under certain conditions, serious vibrations of the blades can occur, involving flatwise bending, torsion, and chordwise bending. A theoretical method of predicting the aeroelastic stability of the coupled bending and torsional motion of such blades with a view to determining the cause of these vibrations, and a means of suppressing them was developed.

Blade Testing Trends (Presentation)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Desmond, M.

2014-08-01

As an invited guest speaker, Michael Desmond presented on NREL's NWTC structural testing methods and capabilities at the 2014 Sandia Blade Workshop held on August 26-28, 2014 in Albuquerque, NM. Although dynamometer and field testing capabilities were mentioned, the presentation focused primarily on wind turbine blade testing, including descriptions and capabilities for accredited certification testing, historical methodology and technology deployment, and current research and development activities.

SSME Turbopump Turbine Computations

NASA Technical Reports Server (NTRS)

Jorgenson, P. G. E.

1985-01-01

A two-dimensional viscous code was developed to be used in the prediction of the flow in the SSME high-pressure turbopump blade passages. The rotor viscous code (RVC) employs a four-step Runge-Kutta scheme to solve the two-dimensional, thin-layer Navier-Stokes equations. The Baldwin-Lomax eddy-viscosity model is used for these turbulent flow calculations. A viable method was developed to use the relative exit conditions from an upstream blade row as the inlet conditions to the next blade row. The blade loading diagrams are compared with the meridional values obtained from an in-house quasithree-dimensional inviscid code. Periodic boundary conditions are imposed on a body-fitted C-grid computed by using the GRAPE GRids about Airfoils using Poisson's Equation (GRAPE) code. Total pressure, total temperature, and flow angle are specified at the inlet. The upstream-running Riemann invariant is extrapolated from the interior. Static pressure is specified at the exit such that mass flow is conserved from blade row to blade row, and the conservative variables are extrapolated from the interior. For viscous flows the noslip condition is imposed at the wall. The normal momentum equation gives the pressure at the wall. The density at the wall is obtained from the wall total temperature.

A review of damage detection methods for wind turbine blades

NASA Astrophysics Data System (ADS)

Li, Dongsheng; Ho, Siu-Chun M.; Song, Gangbing; Ren, Liang; Li, Hongnan

2015-03-01

Wind energy is one of the most important renewable energy sources and many countries are predicted to increase wind energy portion of their whole national energy supply to about twenty percent in the next decade. One potential obstacle in the use of wind turbines to harvest wind energy is the maintenance of the wind turbine blades. The blades are a crucial and costly part of a wind turbine and over their service life can suffer from factors such as material degradation and fatigue, which can limit their effectiveness and safety. Thus, the ability to detect damage in wind turbine blades is of great significance for planning maintenance and continued operation of the wind turbine. This paper presents a review of recent research and development in the field of damage detection for wind turbine blades. Specifically, this paper reviews frequently employed sensors including fiber optic and piezoelectric sensors, and four promising damage detection methods, namely, transmittance function, wave propagation, impedance and vibration based methods. As a note towards the future development trend for wind turbine sensing systems, the necessity for wireless sensing and energy harvesting is briefly presented. Finally, existing problems and promising research efforts for online damage detection of turbine blades are discussed.

Signature management of radar returns from wind turbine generators

NASA Astrophysics Data System (ADS)

Tennant, A.; Chambers, B.

2006-04-01

The large radar cross section of wind turbine generator (WTG) blades combined with high tip speeds can produce significant Doppler returns when illuminated by a radar. Normally, an air traffic control radar system will filter out large returns from stationary targets, but the Doppler shifts introduced by the WTG blades are interpreted as moving aircraft that can confuse radar operators and compromise safety. A possible solution to this problem is to incorporate an active layer into the structure of the WTG blades that can be used to dynamically modulate the radar cross section (RCS) of the blade return. The active blade can operate in one of two modes: first the blade RCS can be modulated to provide a Doppler return that is outside the detectable range of the radar receiver system so that it is rejected; a second mode of operation is to introduce specific coding onto the Doppler returns so that they may be uniquely identified and rejected. The active layer used in the system consists of a frequency selective surface controlled by semiconductor diodes and is a development of techniques developed for active radar absorbers. Results of theoretical and experimental work using a 10 GHz Doppler radar and scale-model WTG are presented.

The dynamics of a flexible bladed disc on a flexible rotor in a two-rotor system

NASA Technical Reports Server (NTRS)

Gallardo, V. C.; Stallone, M. J.

1984-01-01

This paper describes the development of the analysis of the transient dynamic response of a bladed disk on a flexible rotor. The rotating flexible bladed disk is considered as a module in a complete turbine engine structure. The analysis of the flexible bladed disk (FBD) module is developed for the non-equilibrated one-diameter axial mode. The FBD motion is considered as a sum of two standing axial waves constrained to the rotor. The FBD is coupled inertially and gyroscopically to its rotor support, and indirectly through connecting elements, to the adjacent rotor and/or other supporting structures. Incorporated in the basic Turbine Engine Transient Response Analysis program (TETRA), the FBD module is demonstrated with a two-rotor model where the FBD can be excited into resonance by an unbalance in the adjacent rotor and at a frequency equal to the differential rotor speed. The FBD module also allows the analysis of two flexible bladed disks in the same rotor.

Development of an embedded thin-film strain-gauge-based SHM network into 3D-woven composite structure for wind turbine blades

NASA Astrophysics Data System (ADS)

Zhao, Dongning; Rasool, Shafqat; Forde, Micheal; Weafer, Bryan; Archer, Edward; McIlhagger, Alistair; McLaughlin, James

2017-04-01

Recently, there has been increasing demand in developing low-cost, effective structure health monitoring system to be embedded into 3D-woven composite wind turbine blades to determine structural integrity and presence of defects. With measuring the strain and temperature inside composites at both in-situ blade resin curing and in-service stages, we are developing a novel scheme to embed a resistive-strain-based thin-metal-film sensory into the blade spar-cap that is made of composite laminates to determine structural integrity and presence of defects. Thus, with fiberglass, epoxy, and a thinmetal- film sensing element, a three-part, low-cost, smart composite laminate is developed. Embedded strain sensory inside composite laminate prototype survived after laminate curing process. The internal strain reading from embedded strain sensor under three-point-bending test standard is comparable. It proves that our proposed method will provide another SHM alternative to reduce sensing costs during the renewable green energy generation.

Induced strain actuation of composite beams and rotor blades with embedded piezoceramic elements

NASA Astrophysics Data System (ADS)

Chen, Peter C.; Chopra, Inderjit

1994-05-01

The objective of this research is to develop a dynamically scaled (Froude scale) helicopter rotor blade with embedded piezoceramic elements as sensors and actuators to control blade vibrations. A 6-ft-diameter two-bladed bearingless rotor model was built, where each blade is embedded with banks of piezoelectric actuators at +/- 45-degree angles with respect to the beam axis on the top and bottom surfaces. A twist distribution along the blade span is achieved through in-phase excitation of the top and bottom actuators at equal potentials, while a bending distribution is achieved through out-of-phase excitation. In order to fix design variables and to optimize blade performance, a uniform strain beam theory is formulated to analytically predict the static bending and torsional response of composite rectangular beams with embedded piezoelectric actuators. Parameters such as bond thicknesses, actuator skew angle, and actuator spacing are investigated by experiments and then validated by theory. The static bending and torsional response of the rotor blades is experimentally measured and correlated with theory. Dynamic torsional and bending responses are experimentally determined for frequencies from 2-120 HZ to assess the viability of a vibration reduction system based on piezoactuation of blade twist. Although the magnitudes of blade twist attained in this experiment were small, it is expected that future models can be built with improved performance.

Evaluation of the New B-REX Fatigue Testing System for Multi-Megawatt Wind Turbine Blades: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

White, D.; Musial, W.; Engberg, S.

2004-12-01

The National Renewable Energy Laboratory (NREL) recently developed a new hybrid fatigue testing system called the Blade Resonance Excitation (B-REX) test system. The new system uses 65% less energy to test large wind turbine blades in half the time of NREL's dual-axis forced-displacement test method with lower equipment and operating costs. The B-REX is a dual-axis test system that combines resonance excitation with forced hydraulic loading to reduce the total test time required while representing the operating strains on the critical inboard blade stations more accurately than a single-axis test system. The analysis and testing required to fully implement themore » B-REX was significant. To control unanticipated blade motion and vibrations caused by dynamic coupling between the flap, lead-lag, and torsional directions, we needed to incorporate additional test hardware and control software. We evaluated the B-REX test system under stable operating conditions using a combination of various sensors. We then compared our results with results from the same blade, tested previously using NREL's dual-axis forced-displacement test method. Experimental results indicate that strain levels produced by the B-REX system accurately replicated the forced-displacement method. This paper describes the challenges we encountered while developing the new blade fatigue test system and the experimental results that validate its accuracy.« less

A Biomimetic Propulsor for Active Noise Control. Part 2: Theory

NASA Astrophysics Data System (ADS)

Annaswamy Krol, A., Jr.; Bandyopadhyay, P. R.

2000-11-01

The alteration of radiated noise in underwater propulsors using biomimetic active control is considered. Wake momentum filling is carried out by introducing artificial muscles at the trailing edge of a stator blade of an upstream stator propulsor, and articulating them like a fish tail (see companion abstract Part 1). Using a systems framework, we derive a methodology for the articulation of the muscles with active control. The unsteady force produced on the rotor because of velocity perturbations due to actuator displacements, wake deficits caused by stator boundary layers, and blade rotation is modeled. Linear and adaptive nonlinear control strategies are described for articulating the tail using unsteady force measurements. This active control procedure can be viewed as the realization of “virtual” blades with different sweep and noise characteristics and can affect the noise spectrum due to direct radiation significantly. The work provides an understanding of the effect of nonuniform wakes on radiated noise and can lead to a general approach by which wakes can be altered.

Helicopter vibration suppression using simple pendulum absorbers on the rotor blade

NASA Technical Reports Server (NTRS)

Pierce, G. A.; Hanouva, M. N. H.

1982-01-01

A comprehensive anaytical design procedure for the installation of simple pendulums on the blades of a helicopter rotor to suppress the root reactions is presented. A frequency response anaysis is conducted of typical rotor blades excited by a harmonic variation of spanwise airload distributions as well as a concentrated load at the tip. The results presented included the effect of pendulum tuning on the minimization of the hub reactions. It is found that a properly designed flapping pendulum attenuates the root out-of-plane force and moment whereas the optimum designed lead-lag pendulum attenuates the root in-plane reactions. For optimum pendulum tuning the parameters to be determined are the pendulum uncoupled natural frequency, the pendulum spanwise location and its mass. It is found that the optimum pendulum frequency is in the vicinity of the excitation frequency. For the optimum pendulum a parametric study is conducted. The parameters varied include prepitch, pretwist, precone and pendulum hinge offset.

CFD analyses for advanced pump design

NASA Technical Reports Server (NTRS)

Dejong, F. J.; Choi, S.-K.; Govindan, T. R.

1994-01-01

As one of the activities of the NASA/MSFC Pump Stage Technology Team, the present effort was focused on using CFD in the design and analysis of high performance rocket engine pumps. Under this effort, a three-dimensional Navier-Stokes code was used for various inducer and impeller flow field calculations. An existing algebraic grid generation procedure was-extended to allow for nonzero blade thickness, splitter blades, and hub/shroud cavities upstream or downstream of the (main) blades. This resulted in a fast, robust inducer/impeller geometry/grid generation package. Problems associated with running a compressible flow code to simulate an incompressible flow were resolved; related aspects of the numerical algorithm (viz., the matrix preconditioning, the artificial dissipation, and the treatment of low Mach number flows) were addressed. As shown by the calculations performed under the present effort, the resulting code, in conjunction with the grid generation package, is an effective tool for the rapid solution of three-dimensional viscous inducer and impeller flows.

Ankle fusion for definitive management of non-reconstructable pilon fractures.

PubMed

Bozic, Vladimir; Thordarson, David B; Hertz, Jennifer

2008-09-01

Highly comminuted pilon fractures, especially with a compromised soft tissue envelope, present a challenging treatment scenario. This study presents our results for patients managed with ankle fusion rather than ORIF. Fourteen patients with ankle joint incongruence after non-reconstructable tibia pilon fractures were treated with primary tibiotalar arthrodesis using a fixed-angle cannulated blade plate. Delayed metaphyseal unions due to bone defects were treated concurrently. The subtalar joint was preserved in all cases. Metaphyseal healing and stable arthrodesis was obtained in each case. There was one case of blade plate breakage in a patient who still achieved successful arthrodesis without reoperation. Union was achieved at an average of 15 weeks. No secondary procedures were required to obtain union. All 14 patients were ambulatory at last followup. Average followup was 39 weeks. Primary ankle arthrodesis can be achieved using a cannulated blade plate to address a non-reconstructable articular surface and metaphyseal bone defects in complex tibia pilon fractures.

An analysis of rotor blade twist variables associated with different Euler sequences and pretwist treatments

NASA Technical Reports Server (NTRS)

Alkire, K.

1984-01-01

A nonlinear analysis which is necessary to adequately model elastic helicopter rotor blades experiencing moderately large deformations was examined. The analysis must be based on an appropriate description of the blade's deformation geometry including elastic bending and twist. Built-in pretwist angles complicate the deformation process ant its definition. Relationships between the twist variables associated with different rotation sequences and corresponding forms of the transformation matrix are lasted. Relationships between the twist variables associated with first, the pretwist combined with the deformation twist are included. Many of the corresponding forms of the transformation matrix for the two cases are listed. It is shown that twist variables connected with the combined twist treatment are related to those where the pretwist is applied initially. A method to determine the relationships and some results are outlined. A procedure to evaluate the transformation matrix that eliminates the Eulerlike sequence altogether is demonstrated. The resulting form of the transformation matrix is unaffected by rotation sequence or pretwist treatment.

Bending mode flutter in a transonic linear cascade

NASA Astrophysics Data System (ADS)

Govardhan, Raghuraman; Jutur, Prahallada

2017-11-01

Vibration related issues like flutter pose a serious challenge to aircraft engine designers. The phenomenon has gained relevance for modern engines that employ thin and long fan blade rows to satisfy the growing need for compact and powerful engines. The tip regions of such blade rows operate with transonic relative flow velocities, and are susceptible to bending mode flutter. In such cases, the flow field around individual blades of the cascade is dominated by shock motions generated by the blade motions. In the present work, a new transonic linear cascade facility with the ability to oscillate a blade at realistic reduced frequencies has been developed. The facility operates at a Mach number of 1.3, with the central blade being oscillated in heave corresponding to the bending mode of the rotor. The susceptibility of the blade to undergo flutter at different reduced frequencies is quantified by the cycle-averaged power transfer to the blade calculated using the measured unsteady load on the oscillating blade. These measurements show fluid excitation (flutter) at low reduced frequencies and fluid damping (no flutter) at higher reduced frequencies. Simultaneous measurements of the unsteady shock motions are done with high speed shadowgraphy to elucidate the differences in shock motions between the excitation and damping cases.

Development and validation of a blade-element mathematical model for the AH-64A Apache helicopter

NASA Technical Reports Server (NTRS)

Mansur, M. Hossein

1995-01-01

A high-fidelity blade-element mathematical model for the AH-64A Apache Advanced Attack Helicopter has been developed by the Aeroflightdynamics Directorate of the U.S. Army's Aviation and Troop Command (ATCOM) at Ames Research Center. The model is based on the McDonnell Douglas Helicopter Systems' (MDHS) Fly Real Time (FLYRT) model of the AH-64A (acquired under contract) which was modified in-house and augmented with a blade-element-type main-rotor module. This report describes, in detail, the development of the rotor module, and presents some results of an extensive validation effort.

Extended aeroelastic analysis for helicopter rotors with prescribed hub motion and blade appended penduluum vibration absorbers

NASA Technical Reports Server (NTRS)

Bielawa, R. L.

1984-01-01

The mathematical development for the expanded capabilities of the G400 rotor aeroelastic analysis was examined. The G400PA expanded analysis simulates the dynamics of all conventional rotors, blade pendulum vibration absorbers, and the higher harmonic excitations resulting from prescribed vibratory hub motions and higher harmonic blade pitch control. The methodology for modeling the unsteady stalled airloads of two dimensional airfoils is discussed. Formulations for calculating the rotor impedance matrix appropriate to the higher harmonic blade excitations are outlined. This impedance matrix, and the associated vibratory hub loads, are the rotor dynamic characteristic elements for use in the simplified coupled rotor/fuselage vibration analysis (SIMVIB). Updates to the development of the original G400 theory, program documentation, user instructions and information are presented.

Structural Analysis and Optimization of a Composite Fan Blade for Future Aircraft Engine

NASA Technical Reports Server (NTRS)

Coroneos, Rula M.

2012-01-01

This report addresses the structural analysis and optimization of a composite fan blade sized for a large aircraft engine. An existing baseline solid metallic fan blade was used as a starting point to develop a hybrid honeycomb sandwich construction with a polymer matrix composite face sheet and honeycomb aluminum core replacing the original baseline solid metallic fan model made of titanium. The focus of this work is to design the sandwich composite blade with the optimum number of plies for the face sheet that will withstand the combined pressure and centrifugal loads while the constraints are satisfied and the baseline aerodynamic and geometric parameters are maintained. To satisfy the requirements, a sandwich construction for the blade is proposed with composite face sheets and a weak core made of honeycomb aluminum material. For aerodynamic considerations, the thickness of the core is optimized whereas the overall blade thickness is held fixed so as to not alter the original airfoil geometry. Weight is taken as the objective function to be minimized by varying the core thickness of the blade within specified upper and lower bounds. Constraints are imposed on radial displacement limitations and ply failure strength. From the optimum design, the minimum number of plies, which will not fail, is back-calculated. The ply lay-up of the blade is adjusted from the calculated number of plies and final structural analysis is performed. Analyses were carried out by utilizing the OpenMDAO Framework, developed at NASA Glenn Research Center combining optimization with structural assessment.

A comparison with theory of peak to peak sound level for a model helicopter rotor generating blade slap at low tip speeds

NASA Technical Reports Server (NTRS)

Fontana, R. R.; Hubbard, J. E., Jr.

1983-01-01

Mini-tuft and smoke flow visualization techniques have been developed for the investigation of model helicopter rotor blade vortex interaction noise at low tip speeds. These techniques allow the parameters required for calculation of the blade vortex interaction noise using the Widnall/Wolf model to be determined. The measured acoustics are compared with the predicted acoustics for each test condition. Under the conditions tested it is determined that the dominating acoustic pulse results from the interaction of the blade with a vortex 1-1/4 revolutions old at an interaction angle of less than 8 deg. The Widnall/Wolf model predicts the peak sound pressure level within 3 dB for blade vortex separation distances greater than 1 semichord, but it generally over predicts the peak S.P.L. by over 10 dB for blade vortex separation distances of less than 1/4 semichord.

A hybrid multi-objective evolutionary algorithm for wind-turbine blade optimization

NASA Astrophysics Data System (ADS)

Sessarego, M.; Dixon, K. R.; Rival, D. E.; Wood, D. H.

2015-08-01

A concurrent-hybrid non-dominated sorting genetic algorithm (hybrid NSGA-II) has been developed and applied to the simultaneous optimization of the annual energy production, flapwise root-bending moment and mass of the NREL 5 MW wind-turbine blade. By hybridizing a multi-objective evolutionary algorithm (MOEA) with gradient-based local search, it is believed that the optimal set of blade designs could be achieved in lower computational cost than for a conventional MOEA. To measure the convergence between the hybrid and non-hybrid NSGA-II on a wind-turbine blade optimization problem, a computationally intensive case was performed using the non-hybrid NSGA-II. From this particular case, a three-dimensional surface representing the optimal trade-off between the annual energy production, flapwise root-bending moment and blade mass was achieved. The inclusion of local gradients in the blade optimization, however, shows no improvement in the convergence for this three-objective problem.

Turbine Blade and Endwall Heat Transfer Measured in NASA Glenn's Transonic Turbine Blade Cascade

NASA Technical Reports Server (NTRS)

Giel, Paul W.

2000-01-01

Higher operating temperatures increase the efficiency of aircraft gas turbine engines, but can also degrade internal components. High-pressure turbine blades just downstream of the combustor are particularly susceptible to overheating. Computational fluid dynamics (CFD) computer programs can predict the flow around the blades so that potential hot spots can be identified and appropriate cooling schemes can be designed. Various blade and cooling schemes can be examined computationally before any hardware is built, thus saving time and effort. Often though, the accuracy of these programs has been found to be inadequate for predicting heat transfer. Code and model developers need highly detailed aerodynamic and heat transfer data to validate and improve their analyses. The Transonic Turbine Blade Cascade was built at the NASA Glenn Research Center at Lewis Field to help satisfy the need for this type of data.

Numerical investigation of heat transfer on film-cooled turbine blades.

PubMed

Ginibre, P; Lefebvre, M; Liamis, N

2001-05-01

The accurate heat transfer prediction of film-cooled blades is a key issue for the aerothermal turbine design. For this purpose, advanced numerical methods have been developed at Snecma Moteurs. The goal of this paper is the assessment of a three-dimensional Navier-Stokes solver, based on the ONERA CANARI-COMET code, devoted to the steady aerothermal computations of film-cooled blades. The code uses a multidomain approach to discretize the blade to blade channel with overlapping structured meshes for the injection holes. The turbulence closure is done by means of either Michel mixing length model or Spalart-Allmaras one transport equation model. Computations of thin 3D slices of three film-cooled nozzle guide vane blades with multiple injections are performed. Aerothermal predictions are compared to experiments carried out by the von Karman Institute. The behavior of the turbulence models is discussed, and velocity and temperature injection profiles are investigated.

Aeroelastic modal characteristics of mistuned blade assemblies: Mode localization and loss of eigenstructure

NASA Technical Reports Server (NTRS)

Pierre, Christophe; Murthy, Durbha V.

1991-01-01

An investigation of the effects of small mistuning on the aeroelastic modes of bladed disk assemblies with aerodynamic coupling between blades is presented. The cornerstone of the approach is the use and development of perturbation methods that exhibit the crucial role of the interblade coupling and yield general findings regarding mistuning effects. It is shown that blade assemblies with weak aerodynamic interblade coupling are highly sensitive to small blade mistuning, and that their dynamics is quantitatively altered in the following ways: the regular pattern that characterizes the root locus of the tuned aeroelastic eigenvalues in the complex plane is totally lost; the aeroelastic mode shapes becomes severely localized to only a few blades of the assembly and lose their constant interblade phase angle feature; and curve veering phenomena take place when the eigenvalues are plotted versus a mistuning parameter.

Comprehensive helicopter rotor instrumentation - A retrofit approach using miniature transducers

NASA Technical Reports Server (NTRS)

Jacklin, Stephen A.; Mort, Ray; Morrison, Dwayne

1992-01-01

This paper reports an approach used to retrofit a set of full-scale main rotor blades with 290 miniature pressure transducers, 46 strain gages, and 24 miniature accelerometers. Normally, in order to avoid disturbing the aerodynamics of the rotor flow field, the pressure instrumentation must be integrally built into the body of the rotor blades. However, using a method developed with NASA, miniature pressure transducers are mounted to the blade exterior surface without degrading the quality of the blade aerodynamics. Moreover, it is estimated that this approach reduced costs by more than 50 percent over building a set of pressure instrumented blades. The aerodynamic measurement objectives are presented as are instrumentation design considerations, type of instrumentation used, assembly process, and the installed instrumentation characteristics.

Shape design and CFD analysis on a 1MW-class horizontal axis tidal current turbine blade

NASA Astrophysics Data System (ADS)

Singh, P. M.; Choi, Y. D.

2013-12-01

This study aims to develop a 1MW-class horizontal axis tidal current turbine rotor blade which can be applied near the southwest island regions of South Korea. On the basis of actual tidal current conditions of southern region of Korea, configuration design of 1MW class turbine rotor blade is carried out by BEMT (Blade element momentum theory). The hydrodynamic performance including the lift and drag forces, is conducted with the variation of the angle of attack using an open source code of X-Foil. The purpose of the study is to study the shape of the hydrofoil used and how it affects the performance of the turbine. After a thorough study of many airfoils, a new hydrofoil is developed using the S814 and DU-91-W2- 250 airfoils, which show good performance for rough conditions. A combination of the upper and lower surface of the two hydrofoils is tested. Three dimensional models were developed and the optimized blade geometry is used for CFD (Computational Fluid Dynamics) analysis with hexahedral numerical grids. Power coefficient, pressure coefficient and velocity distributions are investigated according to Tip Speed Ratio by CFD analysis.

Wire blade development for Fixed Abrasive Slicing Technique (FAST) slicing

NASA Technical Reports Server (NTRS)

Khattak, C. P.; Schmid, F.; Smith, M. B.

1982-01-01

A low cost, effective slicing method is essential to make ingot technology viable for photovoltaics in terrestrial applications. The fixed abrasive slicing technique (FAST) combines the advantages of the three commercially developed techniques. In its development stage FAST demonstrated cutting effectiveness of 10 cm and 15 cm diameter workpieces. Wire blade development is still the critical element for commercialization of FAST technology. Both impregnated and electroplated wire blades have been developed; techniques have been developed to fix diamonds only in the cutting edge of the wire. Electroplated wires show the most near term promise and this approach is emphasized. With plated wires it has been possible to control the size and shape of the electroplating, it is expected that this feature reduces kerf and prolongs the life of the wirepack.

Experimental study of rotating wind turbine breakdown characteristics in large scale air gaps

NASA Astrophysics Data System (ADS)

Wang, Yu; Qu, Lu; Si, Tianjun; Ni, Yang; Xu, Jianwei; Wen, Xishan

2017-06-01

When a wind turbine is struck by lightning, its blades are usually rotating. The effect of blade rotation on a turbine’s ability to trigger a lightning strike is unclear. Therefore, an arching electrode was used in a wind turbine lightning discharge test to investigate the difference in lightning triggering ability when blades are rotating and stationary. A negative polarity switching waveform of 250/2500 μs was applied to the arching electrode and the up-and-down method was used to calculate the 50% discharge voltage. Lightning discharge tests of a 1:30 scale wind turbine model with 2, 4, and 6 m air gaps were performed and the discharge process was observed. The experimental results demonstrated that when a 2 m air gap was used, the breakdown voltage increased as the blade speed was increased, but when the gap length was 4 m or longer, the trend was reversed and the breakdown voltage decreased. The analysis revealed that the rotation of the blades changes the charge distribution in the blade-tip region, promotes upward leader development on the blade tip, and decreases the breakdown voltage. Thus, the blade rotation of a wind turbine increases its ability to trigger lightning strikes.

Stator Blade with Thermal Barrier Testing on Hot Gas Rig

NASA Image and Video Library

1975-04-21

A 1-foot long stator blade with a thermal coating subjected to intense heat in order to test its strength at the National Aeronautics and Space Administration (NASA) Lewis Research Center. Lewis researchers sought to determine optimal types of ceramic coatings to increase the durability of metals. The research was primarily intended to support the design of stator blades for high-performance axial-flow compressor and turbofan engines. The coatings reduced the temperature of the metal and the amount of required cooling. As engines became more and more sophisticated, compressor blades were required to withstand higher and higher temperatures. Lewis researchers developed a dual-layer thermal-barrier coating that could be applied to turbine vanes and blades and combustion liners. This new sprayable thermal-barrier coating was evaluated for its durability, strength, fatigue, and aerodynamic penalties. This hot-gas rig fired the scorching gas at the leading edge of a test blade. The blade was cooled by an internal air flow. The blades were heated at two different velocities during the program. When using Mach 0.3 gases the entire heating and cooling cycle only lasted 30 seconds. The cycle lasted 60 minutes during tests at Mach 1.

Improved method for sectioning pectoral spines of catfish for age determination

USGS Publications Warehouse

Blouin, Marc A.; Hall, Glenda R.

1990-01-01

The advantages of this method are: (1) spine sections are clear, with uniform thickness and little tissue damage; (2) no time-consuming procedures are necessary; (3) the original spine remains intact for future sectioning; and (4) the thick, single blade does not warp.

Unsteady and Three-Dimensional Flow in Turbomachines

DTIC Science & Technology

1999-12-01

designers must mitigate possible blade vibrations in the turbomachinery stages. The cyclical stresses associated with blade vibration can rapidly accrue... vibrational instability. In particular, the focus is upon developing a rational methodology towards "flutter clearance" that is, towards ensuring...model of the rotor that considers a single mode of vibration for each blade, as schematically represented in Fig. 4.2a. Under a coordinate

Methods of Enhancing the Operating Characteristics of Gas-Turbine Blades

NASA Astrophysics Data System (ADS)

Ospennikova, O. G.; Visik, E. M.; Gerasimov, V. V.; Kolyadov, E. V.

2017-12-01

This paper considers the main tendencies of development and ways of introduction of new technological solutions and alloys in the production of industrial gas-turbine unit (GTU) blades and presents a review of modern corrosion-resistant alloys, casting units for high-gradient directional solidification, and the techniques providing the preparation of a single-crystal structure in the blades of stationary turbine plants.

Nonlinear vibration analysis of bladed disks with dry friction dampers

NASA Astrophysics Data System (ADS)

Ciğeroğlu, Ender; Özgüven, H. Nevzat

2006-08-01

In this work, a new model is proposed for the vibration analysis of turbine blades with dry friction dampers. The aim of the study is to develop a multiblade model that is accurate and yet easy to be analyzed so that it can be used efficiently in the design of friction dampers. The suggested nonlinear model for a bladed disk assembly includes all the blades with blade to blade and/or blade to cover plate dry friction dampers. An important feature of the model is that both macro-slip and micro-slip models are used in representing dry friction dampers. The model is simple to be analyzed as it is the case in macro-slip model, and yet it includes the features of more realistic micro-slip model. The nonlinear multidegree-of-freedom (mdof) model of bladed disk system is analyzed in frequency domain by applying a quasi-linearization technique, which transforms the nonlinear differential equations into a set of nonlinear algebraic equations. The solution method employed reduces the computational effort drastically compared to time solution methods for nonlinear systems, which makes it possible to obtain a more realistic model by the inclusion of all blades around the disk, disk itself and all friction dampers since in general system parameters are not identical throughout the geometry. The validation of the method is demonstrated by comparing the results obtained in this study with those given in literature and also with results obtained by time domain analysis. In the case studies presented the effect of friction damper parameters on vibration characteristics of tuned and mistuned bladed disk systems is studied by using a 20 blade system. It is shown that the method presented can be used to find the optimum friction damper values in a bladed disk assembly.

Material development for fan blade containment casing

NASA Astrophysics Data System (ADS)

McMillan, A.

2008-03-01

This paper describes the physics reasoning and the engineering development process for the structured material system adopted for the containment system of the Trent 900 engine. This is the Rolls-Royce engine that powers the Airbus A380 double-decker aeroplane, which is on the point of entering service. The fan blade containment casing is the near cylindrical casing that surrounds the fan blades at the front of the engine. The fan blades provide the main part of the thrust of the engine; the power to the fan is provided through a shaft from the turbine. The fan is approximately three meters in diameter, with the tips of the blade travelling at a little over Mach speed. The purpose of the containment system is to catch and contain a blade in the extremely unlikely event of a part or whole blade becoming detached. This is known as a ''Fan Blade Off (FBO)'' event. The requirement is that no high-energy fragments should escape the containment system; this is essential to prevent damage to other engines or to the fuselage of the aircraft. Traditionally the containment system philosophy has been to provide a sufficiently thick solid metallic skin that the blade cannot penetrate. Obviously, this is heavy. A good choice of metal in this case is a highly ductile steel, which arrests the kinetic energy of the blade through plastic deformation, and possibly, a controlled amount of cracking. This is known as ''hard wall'' containment. More recently, to reduce weight, containment systems have incorporated a Kevlar fibre wrap. In this case, the thinner metallic wall provides some containment, which is backed up by the stretching of the Kevlar fibres. This is known as ''soft wall'' containment; but it suffers the disadvantage of requiring a large empty volume in the nacelle in to which to expand. For the Trent 900 engine, there was a requirement to make a substantial weight saving while still adopting a hard wall style of containment system. To achieve this, a hollow structured material system was developed, with much of the kinetic energy arrest provided by the mechanism of crushing. A number of structural elements were included within the containment system to maximise the area of material involved in the arrest and thereby minimise the overall weight.

Using digital image correlation and three dimensional point tracking in conjunction with real time operating data expansion techniques to predict full-field dynamic strain

NASA Astrophysics Data System (ADS)

Avitabile, Peter; Baqersad, Javad; Niezrecki, Christopher

2014-05-01

Large structures pose unique difficulties in the acquisition of measured dynamic data with conventional techniques that are further complicated when the structure also has rotating members such as wind turbine blades and helicopter blades. Optical techniques (digital image correlation and dynamic point tracking) are used to measure line of sight data without the need to contact the structure, eliminating cumbersome cabling issues. The data acquired from these optical approaches are used in conjunction with a unique real time operating data expansion process to obtain full-field dynamic displacement and dynamic strain. The measurement approaches are described in this paper along with the expansion procedures. The data is collected for a single blade from a wind turbine and also for a three bladed assembled wind turbine configuration. Measured strains are compared to results from a limited set of optical measurements used to perform the expansion to obtain full-field strain results including locations that are not available from the line of sight measurements acquired. The success of the approach clearly shows that there are some very extraordinary possibilities that exist to provide very desperately needed full field displacement and strain information that can be used to help identify the structural health of structures.

Transonic rotor tip design using numerical optimization

NASA Technical Reports Server (NTRS)

Tauber, Michael E.; Langhi, Ronald G.

1985-01-01

The aerodynamic design procedure for a new blade tip suitable for operation at transonic speeds is illustrated. For the first time, 3 dimensional numerical optimization was applied to rotor tip design, using the recent derivative of the ROT22 code, program R22OPT. Program R22OPT utilized an efficient quasi-Newton optimization algorithm. Multiple design objectives were specified. The delocalization of the shock wave was to be eliminated in forward flight for an advance ratio of 0.41 and a tip Mach number of 0.92 at psi = 90 deg. Simultaneously, it was sought to reduce torque requirements while maintaining effective restoring pitching moments. Only the outer 10 percent of the blade span was modified; the blade area was not to be reduced by more than 3 percent. The goal was to combine the advantages of both sweptback and sweptforward blade tips. A planform that featured inboard sweepback was combined with a sweptforward tip and a taper ratio of 0.5. Initially, the ROT22 code was used to find by trial and error a planform geometry which met the design goals. This configuration had an inboard section with a leading edge sweep of 20 deg and a tip section swept forward at 25 deg; in addition, the airfoils were modified.

Material Constitutive Models for Creep and Rupture of SiC/SiC Ceramic-Matrix Composites (CMCs) Under Multiaxial Loading

NASA Astrophysics Data System (ADS)

Grujicic, Mica; Galgalikar, R.; Snipes, J. S.; Ramaswami, S.

2016-05-01

Material constitutive models for creep deformation and creep rupture of the SiC/SiC ceramic-matrix composites (CMCs) under general three-dimensional stress states have been developed and parameterized using one set of available experimental data for the effect of stress magnitude and temperature on the time-dependent creep deformation and rupture. To validate the models developed, another set of available experimental data was utilized for each model. The models were subsequently implemented in a user-material subroutine and coupled with a commercial finite element package in order to enable computational analysis of the performance and durability of CMC components used in high-temperature high-stress applications, such as those encountered in gas-turbine engines. In the last portion of the work, the problem of creep-controlled contact of a gas-turbine engine blade with the shroud is investigated computationally. It is assumed that the blade is made of the SiC/SiC CMC, and that the creep behavior of this material can be accounted for using the material constitutive models developed in the present work. The results clearly show that the blade-tip/shroud clearance decreases and ultimately becomes zero (the condition which must be avoided) as a function of time. In addition, the analysis revealed that if the blade is trimmed at its tip to enable additional creep deformation before blade-tip/shroud contact, creep-rupture conditions can develop in the region of the blade adjacent to its attachment to the high-rotational-speed hub.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rajagopal, K. R.; Rao, I. J.

The procedures in place for producing materials in order to optimize their performance with respect to creep characteristics, oxidation resistance, elevation of melting point, thermal and electrical conductivity and other thermal and electrical properties are essentially trial and error experimentation that tend to be tremendously time consuming and expensive. A computational approach has been developed that can replace the trial and error procedures in order that one can efficiently design and engineer materials based on the application in question can lead to enhanced performance of the material, significant decrease in costs and cut down the time necessary to produce suchmore » materials. The work has relevance to the design and manufacture of turbine blades operating at high operating temperature, development of armor and missiles heads; corrosion resistant tanks and containers, better conductors of electricity, and the numerous other applications that are envisaged for specially structured nanocrystalline solids. A robust thermodynamic framework is developed within which the computational approach is developed. The procedure takes into account microstructural features such as the dislocation density, lattice mismatch, stacking faults, volume fractions of inclusions, interfacial area, etc. A robust model for single crystal superalloys that takes into account the microstructure of the alloy within the context of a continuum model is developed. Having developed the model, we then implement in a computational scheme using the software ABAQUS/STANDARD. The results of the simulation are compared against experimental data in realistic geometries.« less

Learning about Poland Anomaly

MedlinePlus

... Sometimes, such abnormal development extends to the shoulder blade or the bones of the arm. Rarely, spine ... in the hand, forearm, ribs and/or shoulder blades. Under mild circumstances, a person may not know ...

Induced strain actuation of composite beams and rotor blades with embedded piezoceramic elements

NASA Astrophysics Data System (ADS)

Chen, Peter C.; Chopra, Inderjit

1996-02-01

The objective of this research is to develop a dynamically-scaled (Froude scale) helicopter rotor blade with embedded piezoceramic elements as sensors and actuators to control blade vibrations. A 6 ft diameter 2-bladed bearingless rotor model was built where each blade is embedded with banks of piezoelectric actuators at 0964-1726/5/1/005/img1 degree angles with respect to the beam axis on the top and bottom surfaces. A twist distribution along the blade span is achieved through in-phase excitation of the top and bottom actuators at equal potentials, while a bending distribution is achieved through out-of-phase excitation. In order to fix design variables and to optimize blade performance, a uniform strain beam theory is formulated to analytically predict the static bending and torsional response of composite rectangular beams with embedded piezoelectric actuators. Parameters such as bond thicknesses, actuator skew angle and actuator spacing are investigated by experiments and then validated by theory. The static bending and torsional response of the rotor blades is experimentally measured and correlated with theory. Dynamic torsional and bending responses are experimentally determined for frequencies from 2 - 120 Hz to assess the viability of a vibration reduction system based on piezo-actuation of blade twist. To assess the performance of the piezo-actuators in rotation, hover tests were conducted where accelerometers embedded in the blades were used to resolve the tip twist amplitudes. Although the magnitudes of blade twist attained in this experiment were small, it is expected that future models can be built with improved performance.

A novel method of strain - bending moment calibration for blade testing

NASA Astrophysics Data System (ADS)

Greaves, P.; Prieto, R.; Gaffing, J.; van Beveren, C.; Dominy, R.; Ingram, G.

2016-09-01

A new method of interpreting strain data in full scale static and fatigue tests has been implemented as part of the Offshore Renewable Energy Catapult's ongoing development of biaxial fatigue testing of wind turbine blades. During bi-axial fatigue tests, it is necessary to be able to distinguish strains arising from the flapwise motion of the blade from strains arising from the edgewise motion. The method exploits the beam-like structure of blades and is derived using the equations of beam theory. It offers several advantages over the current state of the art method of calibrating strain gauges.

High Aspect-Ratio Neural Probes using Conventional Blade Dicing

NASA Astrophysics Data System (ADS)

Goncalves, S. B.; Ribeiro, J. F.; Silva, A. F.; Correia, J. H.

2016-10-01

Exploring deep neural circuits has triggered the development of long penetrating neural probes. Moreover, driven by brain displacement, the long neural probes require also a high aspect-ratio shafts design. In this paper, a simple and reproducible method of manufacturing long-shafts neural probes using blade dicing technology is presented. Results shows shafts up to 8 mm long and 200 µm wide, features competitive to the current state-of-art, being its outline simply accomplished by a single blade dicing program. Therefore, conventional blade dicing presents itself as a viable option to manufacture long neural probes.

Thin-film sensors for reusable space propulsion systems

NASA Technical Reports Server (NTRS)

Hepp, Aloysius F.; Kim, Walter S.

1989-01-01

Thin-film thermocouples (TFTCs) were developed for aircraft gas turbine engines and are in use for temperature measurement on turbine blades up to 1800 F. Established aircraft engine gas turbine technology is currently being adapted to turbine engine blade materials and the environment encountered in the Space Shuttle Main Engine (SSME)-severe thermal shock from cryogenic fuel to combustion temperatures. Initial results with coupons of MAR M-246 (+Hf) and PWA 1480 were followed by fabrication of TFTC on SSME turbine blades. Current efforts are focused on preparation for testing in the Turbine Blade Tester at NASA Marshall Space Flight Center.

Development of a three-dimensional multistage inverse design method for aerodynamic matching of axial compressor blading

NASA Astrophysics Data System (ADS)

van Rooij, Michael P. C.

Current turbomachinery design systems increasingly rely on multistage Computational Fluid Dynamics (CFD) as a means to assess performance of designs. However, design weaknesses attributed to improper stage matching are addressed using often ineffective strategies involving a costly iterative loop between blading modification, revision of design intent, and evaluation of aerodynamic performance. A design methodology is presented which greatly improves the process of achieving design-point aerodynamic matching. It is based on a three-dimensional viscous inverse design method which generates the blade camber surface based on prescribed pressure loading, thickness distribution and stacking line. This inverse design method has been extended to allow blading analysis and design in a multi-blade row environment. Blade row coupling was achieved through a mixing plane approximation. Parallel computing capability in the form of MPI has been implemented to reduce the computational time for multistage calculations. Improvements have been made to the flow solver to reach the level of accuracy required for multistage calculations. These include inclusion of heat flux, temperature-dependent treatment of viscosity, and improved calculation of stress components and artificial dissipation near solid walls. A validation study confirmed that the obtained accuracy is satisfactory at design point conditions. Improvements have also been made to the inverse method to increase robustness and design fidelity. These include the possibility to exclude spanwise sections of the blade near the endwalls from the design process, and a scheme that adjusts the specified loading area for changes resulting from the leading and trailing edge treatment. Furthermore, a pressure loading manager has been developed. Its function is to automatically adjust the pressure loading area distribution during the design calculation in order to achieve a specified design objective. Possible objectives are overall mass flow and compression ratio, and radial distribution of exit flow angle. To supplement the loading manager, mass flow inlet and exit boundary conditions have been implemented. Through appropriate combination of pressure or mass flow inflow/outflow boundary conditions and loading manager objectives, increased control over the design intent can be obtained. The three-dimensional multistage inverse design method with pressure loading manager was demonstrated to offer greatly enhanced blade row matching capabilities. Multistage design allows for simultaneous design of blade rows in a mutually interacting environment, which permits the redesigned blading to adapt to changing aerodynamic conditions resulting from the redesign. This ensures that the obtained blading geometry and performance implied by the prescribed pressure loading distribution are consistent with operation in the multi-blade row environment. The developed methodology offers high aerodynamic design quality and productivity, and constitutes a significant improvement over existing approaches used to address design-point aerodynamic matching.

Role of Wind Tunnels and Computer Codes in the Certification and Qualification of Rotorcraft for Flight in Forecast Icing

NASA Technical Reports Server (NTRS)

Flemming, Robert J.; Britton, Randall K.; Bond, Thomas H.

1994-01-01

The cost and time to certify or qualify a rotorcraft for flight in forecast icing has been a major impediment to the development of ice protection systems for helicopter rotors. Development and flight test programs for those aircraft that have achieved certification or qualification for flight in icing conditions have taken many years, and the costs have been very high. NASA, Sikorsky, and others have been conducting research into alternative means for providing information for the development of ice protection systems, and subsequent flight testing to substantiate the air-worthiness of a rotor ice protection system. Model rotor icing tests conducted in 1989 and 1993 have provided a data base for correlation of codes, and for the validation of wind tunnel icing test techniques. This paper summarizes this research, showing test and correlation trends as functions of cloud liquid water content, rotor lift, flight speed, and ambient temperature. Molds were made of several of the ice formations on the rotor blades. These molds were used to form simulated ice on the rotor blades, and the blades were then tested in a wind tunnel to determine flight performance characteristics. These simulated-ice rotor performance tests are discussed in the paper. The levels of correlation achieved and the role of these tools (codes and wind tunnel tests) in flight test planning, testing, and extension of flight data to the limits of the icing envelope are discussed. The potential application of simulated ice, the NASA LEWICE computer, the Sikorsky Generalized Rotor Performance aerodynamic computer code, and NASA Icing Research Tunnel rotor tests in a rotorcraft certification or qualification program are also discussed. The correlation of these computer codes with tunnel test data is presented, and a procedure or process to use these methods as part of a certification or qualification program is introduced.

Full-scale fatigue tests of CX-100 wind turbine blades. Part I: testing

NASA Astrophysics Data System (ADS)

Farinholt, Kevin M.; Taylor, Stuart G.; Park, Gyuhae; Ammerman, Curtt M.

2012-04-01

This paper overviews the test setup and experimental methods for structural health monitoring (SHM) of two 9-meter CX-100 wind turbine blades that underwent fatigue loading at the National Renewable Energy Laboratory's (NREL) National Wind Technology Center (NWTC). The first blade was a pristine blade, which was manufactured to standard specifications for the CX-100 design. The second blade was manufactured for the University of Massachusetts, Lowell with intentional simulated defects within the fabric layup. Each blade was instrumented with piezoelectric transducers, accelerometers, acoustic emission sensors, and foil strain gauges. The blades underwent harmonic excitation at their first natural frequency using the Universal Resonant Excitation (UREX) system at NREL. Blades were initially excited at 25% of their design load, and then with steadily increasing loads until each blade reached failure. Data from the sensors were collected between and during fatigue loading sessions. The data were measured over multi-scale frequency ranges using a variety of acquisition equipment, including off-the-shelf systems and specially designed hardware developed at Los Alamos National Laboratory (LANL). The hardware systems were evaluated for their aptness in data collection for effective application of SHM methods to the blades. The results of this assessment will inform the selection of acquisition hardware and sensor types to be deployed on a CX-100 flight test to be conducted in collaboration with Sandia National Laboratory at the U.S. Department of Agriculture's (USDA) Conservation and Production Research Laboratory (CPRL) in Bushland, Texas.

Development of Self-Powered Wireless Structural Health Monitoring (SHM) for Wind Turbine Blades

NASA Astrophysics Data System (ADS)

Lim, Dong-Won

Wind turbine blade failure can lead to unexpected power interruptions. Monitoring wind turbine blades is important to ensure seamless electricity delivery from power generation to consumers. Structural health monitoring (SHM) enables early recognition of structural problems so that the safety and reliability of operation can be enhanced. This dissertation focuses on the development of a wireless SHM system for wind turbine blades. The sensor is comprised of a piezoelectric energy harvester (EH) and a telemetry unit. The sensor node is mounted on the blade surface. As the blade rotates, the blade flexes, and the energy harvester captures the strain energy on the blade surface. Once sufficient electricity is captured, a pulse is sent from the sensing node to a gateway. Then, a central monitoring algorithm processes a series of pulses received from all three blades. This wireless SHM, which uses commercially available components, can be retrofitted to existing turbines. The harvested energy for sensing can be estimated in terms of two factors: the available strain energy and conversion efficiency. The available strain energy was evaluated using the FAST (Fatigue, Aerodynamics, Structures, and Turbulence) simulator. The conversion efficiency was studied analytically and experimentally. An experimental set-up was designed to mimic the expected strain frequency and amplitude for rotor blades. From a series of experiments, the efficiency of a piezoelectric EH at a typical rotor speed (0.2 Hz) was approximately 0.5%. The power requirement for sending one measurement (280 muJ) can be achieved in 10 minutes. Designing a detection algorithm is challenging due to this low sampling rate. A new sensing approach-the timing of pulses from the transmitter-was introduced. This pulse timing, which is tied to the charging time, is indicative of the structural health. The SHM system exploits the inherent triple redundancy of the three blades. The timing data of the three blades are compared to discern an outlier, corresponding to a damaged blade. Two types of post-processing of pulses were investigated: (1) comparing the ratios of signal timings (i.e. transmission ratio); and (2) comparing the difference between signal timings (i.e. residuals). For either method, damage is indicated when the energy ratio or residual exceeds a threshold level. When residuals are used to detect damage, performance measures such as the false alarm rate and detection probability can also be imposed. The SHM algorithms were evaluated using strain energy data from a 2.5 MW wind turbine.

Unsteady flows in rotor-stator cascades

NASA Astrophysics Data System (ADS)

Lee, Yu-Tai; Bein, Thomas W.; Feng, Jin Z.; Merkle, Charles L.

1991-03-01

A time-accurate potential-flow calculation method has been developed for unsteady incompressible flows through two-dimensional multi-blade-row linear cascades. The method represents the boundary surfaces by distributing piecewise linear-vortex and constant-source singularities on discrete panels. A local coordinate is assigned to each independently moving object. Blade-shed vorticity is traced at each time step. The unsteady Kutta condition applied is nonlinear and requires zero blade trailing-edge loading at each time. Its influence on the solutions depends on the blade trailing-edge shapes. Steady biplane and cascade solutions are presented and compared to exact solutions and experimental data. Unsteady solutions are validated with the Wagner function for an airfoil moving impulsively from rest and the Theodorsen function for an oscillating airfoil. The shed vortex motion and its interaction with blades are calculated and compared to an analytic solution. For multi-blade-row cascade, the potential effect between blade rows is predicted using steady and quasi unsteady calculations. The accuracy of the predictions is demonstrated using experimental results for a one-stage turbine stator-rotor.

Genetic similarity analysis within Pyropia yezoensis blades developed from both conchospores and blade archeospores using AFLP(1).

PubMed

He, Linwen; Zhu, Jianyi; Lu, Qinqin; Niu, Jianfeng; Zhang, Baoyu; Lin, Apeng; Wang, Guangce

2013-06-01

Pyropia yezoensis (Ueda) M. S. Hwang et H. G. Choi (previously called Porphyra yezoensis) is an economically important alga. The blades generated from conchospores are genetic chimeras, which are not suitable for genetic similarity analysis. In this study, two types of blades from a single filament of P. yezoensis sporophyte filament were obtained. One type, ConB, consisted of 40 blades that had germinated from conchospores. The other type, ArcB, consisted of 88 blades that had germinated from archeospores released from ConB. Both of them were analyzed by amplified fragment length polymorphism. The low genetic similarity levels for both conchospore-germinated and archeospore-germinated blades demonstrated that the conchcelis we used was cross-fertilized. Furthermore, a higher polymorphic loci ratio (98.6%) was detected in ArcB than in ConB (80.7%), and the average genetic similarity of ArcB (average 0.61) was lower than that of ConB (average 0.71). These differences indicated that genetic analysis using ArcB gives more accurate results. © 2013 Phycological Society of America.

The dynamic flexural response of propeller blades. M.S. Thesis

NASA Technical Reports Server (NTRS)

Djordjevic, S. Z.

1982-01-01

The determination of the torsional constants of three blade models having NACA four-digit symmetrical airfoil cross sections is presented. Values were obtained for these models analytically and experimentally. Results were also obtained for three other models having rectangular, elliptical, and parabolic cross sections. Complete modal analyses were performed for five blade models. The identification of modal parameters was done for cases when the blades were modeled as either undamped or damped multi-degree-of-freedom systems. For the experimental phase of this study, the modal testing was performed using a Dual Channel FFT analyzer and an impact hammer (which produced an impulsive excitation). The natural frequency and damping of each mode in the frequency range up to 2 kHz were measured. A small computer code was developed to calculate the dynamic response of the blade models for comparison with the experimental results. A comparison of the undamped and damped cases was made for all five blade models at the instant of maximum excitation force. The program was capable of handling models where the excitation forces were distributed arbitrarily along the length of the blade.

Improved motion correction in PROPELLER by using grouped blades as reference.

PubMed

Liu, Zhe; Zhang, Zhe; Ying, Kui; Yuan, Chun; Guo, Hua

2014-03-01

To develop a robust reference generation method for improving PROPELLER (Periodically Rotated Overlapping ParallEL Lines with Enhanced Reconstruction) reconstruction. A new reference generation method, grouped-blade reference (GBR), is proposed for calculating rotation angle and translation shift in PROPELLER. Instead of using a single-blade reference (SBR) or combined-blade reference (CBR), our method classifies blades by their relative correlations and groups similar blades together as the reference to prevent inconsistent data from interfering the correction process. Numerical simulations and in vivo experiments were used to evaluate the performance of GBR for PROPELLER, which was further compared with SBR and CBR in terms of error level and computation cost. Both simulation and in vivo experiments demonstrate that GBR-based PROPELLER provides better correction for random motion or bipolar motion comparing with SBR or CBR. It not only produces images with lower error level but also needs less iteration steps to converge. A grouped-blade for reference selection was investigated for PROPELLER MRI. It helps to improve the accuracy and robustness of motion correction for various motion patterns. Copyright © 2013 Wiley Periodicals, Inc.

Collecting Currents with Water Turbines

NASA Astrophysics Data System (ADS)

Allen, J.; Allen, S.

2017-12-01

Our science poster is inspired by Florida Atlantic University's recent program to develop three types of renewable energy. They are using water turbines and the Gulf Stream Current to produce a renewable energy source. Wave, tidal and current driven energy. Our poster is called "Collecting Currents with Water Turbines". In our science poster, the purpose was to see which turbine design could produce the most power. We tested three different variables, the number of blades (four, six, and eight), the material of the blades and the shape of the blades. To test which number of blades produced the most power we cut slits into a cork. We used plastic from a soda bottle to make the blades and then we put the blades in the cork to make the turbines. We observed each blade and how much time it took for the water turbines to pull up 5 pennies. Currently water turbines are used in dams to make hydroelectric energy. But with FAU we could understand how to harness the Gulf Stream current off Florida's coast we could soon have new forms of renewable energy.

Controlled laboratory testing of arthroscopic shaver systems: do blades, contact pressure, and speed influence their performance?

PubMed

Wieser, Karl; Erschbamer, Matthias; Neuhofer, Stefan; Ek, Eugene T; Gerber, Christian; Meyer, Dominik C

2012-10-01

The purposes of this study were (1) to establish a reproducible, standardized testing protocol to evaluate the performance of different shaver systems and blades in a controlled, laboratory setting, and (2) to determine the optimal use of different blades with respect to the influence of contact pressure and speed of blade rotation. A holding device was developed for reproducible testing of soft-tissue (tendon and meniscal) resection performance in a submerged environment, after loading of the shaver with interchangeable weights. The Karl Storz Powershaver S2 (Karl Storz, Tuttlingen, Germany), the Stryker Power Shaver System (Stryker, Kalamazoo, MI), and the Dyonics Power Shaver System (Smith & Nephew, Andover, MA) were tested, with different 5.5-mm shaver blades and varied contact pressure and rotation speed. For quality testing, serrated shaver blades were evaluated at 40× image magnification. Overall, more than 150 test cycles were performed. No significant differences could be detected between comparable blade types from different manufacturers. Shavers with a serrated inner blade and smooth outer blade performed significantly better than the standard smooth resectors (P < .001). Teeth on the outer layer of the blade did not lead to any further improvement of resection (P = .482). Optimal contact pressure ranged between 6 and 8 N, and optimal speed was found to be 2,000 to 2,500 rpm. Minimal blunting of the shaver blades occurred after soft-tissue resection; however, with bone resection, progressive blunting of the shaver blades was observed. Arthroscopic shavers can be tested in a controlled setting. The performance of the tested shaver types appears to be fairly independent of the manufacturer. For tendon resection, a smooth outer blade and serrated inner blade were optimal. This is one of the first established independent and quantitative assessments of arthroscopic shaver systems and blades. We believe that this study will assist the surgeon in choosing the optimal tool for the desired effect. Copyright © 2012 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Design optimization for active twist rotor blades

NASA Astrophysics Data System (ADS)

Mok, Ji Won

This dissertation introduces the process of optimizing active twist rotor blades in the presence of embedded anisotropic piezo-composite actuators. Optimum design of active twist blades is a complex task, since it involves a rich design space with tightly coupled design variables. The study presents the development of an optimization framework for active helicopter rotor blade cross-sectional design. This optimization framework allows for exploring a rich and highly nonlinear design space in order to optimize the active twist rotor blades. Different analytical components are combined in the framework: cross-sectional analysis (UM/VABS), an automated mesh generator, a beam solver (DYMORE), a three-dimensional local strain recovery module, and a gradient based optimizer within MATLAB. Through the mathematical optimization problem, the static twist actuation performance of a blade is maximized while satisfying a series of blade constraints. These constraints are associated with locations of the center of gravity and elastic axis, blade mass per unit span, fundamental rotating blade frequencies, and the blade strength based on local three-dimensional strain fields under worst loading conditions. Through pre-processing, limitations of the proposed process have been studied. When limitations were detected, resolution strategies were proposed. These include mesh overlapping, element distortion, trailing edge tab modeling, electrode modeling and foam implementation of the mesh generator, and the initial point sensibility of the current optimization scheme. Examples demonstrate the effectiveness of this process. Optimization studies were performed on the NASA/Army/MIT ATR blade case. Even though that design was built and shown significant impact in vibration reduction, the proposed optimization process showed that the design could be improved significantly. The second example, based on a model scale of the AH-64D Apache blade, emphasized the capability of this framework to explore the nonlinear design space of complex planform. Especially for this case, detailed design is carried out to make the actual blade manufacturable. The proposed optimization framework is shown to be an effective tool to design high authority active twist blades to reduce vibration in future helicopter rotor blades.

High-precision reflectivity measurements: improvements in the calibration procedure

NASA Astrophysics Data System (ADS)

Jupe, Marco; Grossmann, Florian; Starke, Kai; Ristau, Detlev

2003-05-01

The development of high quality optical components is heavily depending on precise characterization procedures. The reflectance and transmittance of laser components are the most important parameters for advanced laser applications. In the industrial fabrication of optical coatings, quality management is generally insured by spectral photometric methods according to ISO/DIS 15386 on a medium level of accuracy. Especially for high reflecting mirrors, a severe discrepancy in the determination of the absolute reflectivity can be found for spectral photometric procedures. In the first part of the CHOCLAB project, a method for measuring reflectance and transmittance with an enhanced precision was developed, which is described in ISO/WD 13697. In the second part of the CHOCLAB project, the evaluation and optimization for the presented method is scheduled. Within this framework international Round-Robin experiment is currently in progress. During this Round-Robin experiment, distinct deviations could be observed between the results of high precision measurement facilities of different partners. Based on the extended experiments, the inhomogeneity of the sample reflectivity was identified as one important origin for the deviation. Consequently, this inhomogeneity is also influencing the calibration procedure. Therefore, a method was developed that allows the calibration of the chopper blade using always the same position on the reference mirror. During the investigations, the homogeneity of several samples was characterized by a surface mapping procedure for 1064 nm. The measurement facility was extended to the additional wavelength 532 nm and a similar set-up was assembled at 10.6 μm. The high precision reflectivity procedure at the mentioned wavelengths is demonstrated for exemplary measurements.