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1

An Experimental/Modeling Study of Jet Attachment during Counterflow Thrust Vectoring  

NASA Technical Reports Server (NTRS)

Recent studies have shown the applicability of vectoring rectangular jets using asymmetrically applied counterflow in the presence of a short collar. This novel concept has applications in the aerospace industry where counterflow can be used to vector the thrust of a jet's exhaust, shortening take-off and landing distances and enhancing in-flight maneuverability of the aircraft. Counterflow thrust vectoring, 'CFTV' is desirable due to its fast time response, low thrust loss, and absence of moving parts. However, implementation of a CFTV system is only possible if bistable jet attachment can be prevented. This can be achieved by properly designing the geometry of the collar. An analytical model is developed herein to predict the conditions under which a two-dimensional jet will attach to an offset curved wall. Results from this model are then compared with experiment; for various jet exit Mach numbers, collar offset distances, and radii of curvature. Their excellent correlation permits use of the model as a tool for designing a CFTV system.

Strykowski, Paul J.

1997-01-01

2

Test stand for precise measurement of impulse and thrust vector of small attitude control jets  

NASA Technical Reports Server (NTRS)

A test stand which accurately measures the impulse bit and thrust vector of reaction jet thrusters used in the attitude control system of space vehicles has been developed. It can be used to measure, in a vacuum or ambient environment, both impulse and thrust vector of reaction jet thrusters using hydrazine or inert gas propellants. The ballistic pendulum configuration was selected because of its accuracy, simplicity, and versatility. The pendulum is mounted on flexure pivots rotating about a vertical axis at the center of its mass. The test stand has the following measurement capabilities: impulse of 0.00004 to 4.4 N-sec (0.00001 to 1.0 lb-sec) with a pulse duration of 0.5 msec to 1 sec; static thrust of 0.22 to 22 N (0.05 to 5 lb) with a 5 percent resolution; and thrust angle alinement of 0.22 to 22 N (0.05 to 5 lb) thrusters with 0.01 deg accuracy.

Woodruff, J. R.; Chisel, D. M.

1973-01-01

3

Aerodynamics of thrust vectoring  

NASA Technical Reports Server (NTRS)

Thrust vectoring as a means to enhance maneuverability and aerodynamic performane of a tactical aircraft is discussed. This concept usually involves the installation of a multifunction nozzle. With the nozzle, the engine thrust can be changed in direction without changing the attitude of the aircraft. Change in the direction of thrust induces a significant change in the aerodynamic forces on the aircraft. Therefore, this device can be used for lift-augmenting as well as stability and control purposes. When the thrust is deflected in the longitudinal direction, the lift force and the pitching stability can be manipulated, while the yawing stability can be controlled by directing the thrust in the lateral direction.

Tseng, J. B.; Lan, C. Edward

1989-01-01

4

Computational Investigation of Fluidic Counterflow Thrust Vectoring  

NASA Technical Reports Server (NTRS)

A computational study of fluidic counterflow thrust vectoring has been conducted. Two-dimensional numerical simulations were run using the computational fluid dynamics code PAB3D with two-equation turbulence closure and linear Reynolds stress modeling. For validation, computational results were compared to experimental data obtained at the NASA Langley Jet Exit Test Facility. In general, computational results were in good agreement with experimental performance data, indicating that efficient thrust vectoring can be obtained with low secondary flow requirements (less than 1% of the primary flow). An examination of the computational flowfield has revealed new details about the generation of a countercurrent shear layer, its relation to secondary suction, and its role in thrust vectoring. In addition to providing new information about the physics of counterflow thrust vectoring, this work appears to be the first documented attempt to simulate the counterflow thrust vectoring problem using computational fluid dynamics.

Hunter, Craig A.; Deere, Karen A.

1999-01-01

5

Design and evaluation of thrust vectored nozzles using a multicomponent thrust stand  

NASA Technical Reports Server (NTRS)

Future aircraft with the capability of short takeoff and landing, and improved maneuverability especially in the post-stall flight regime will incorporate exhaust nozzles which can be thrust vectored. In order to conduct thrust vector research in the Mechanical Engineering Department at Cal Poly, a program was planned with two objectives; design and construct a multicomponent thrust stand for the specific purpose of measuring nozzle thrust vectors; and to provide quality low moisture air to the thrust stand for cold flow nozzle tests. The design and fabrication of the six-component thrust stand was completed. Detailed evaluation tests of the thrust stand will continue upon the receipt of one signal conditioning option (-702) for the Fluke Data Acquisition System. Preliminary design of thrust nozzles with air supply plenums were completed. The air supply was analyzed with regard to head loss. Initial flow visualization tests were conducted using dual water jets.

Carpenter, Thomas W.; Blattner, Ernest W.; Stagner, Robert E.; Contreras, Juanita; Lencioni, Dennis; Mcintosh, Greg

1990-01-01

6

Analysis of stratified and closely spaced jets exhausting into a crossflow. [aerodynamic characteristics of lift-jet, vectored thrust, and lift fan V/STOL aircraft  

NASA Technical Reports Server (NTRS)

Procedures have been developed for determining the flow field about jets with velocity stratification exhausting into a crossflow. Jets with three different types of exit velocity stratification have been considered: (1) jets with a relatively high velocity core; (2) jets with a relatively low velocity core; and (3) jets originating from a vaned nozzle. The procedure developed for a jet originating from a high velocity core nozzle is to construct an equivalent nozzle having the same mass flow and thrust but having a uniform exit velocity profile. Calculations of the jet centerline and induced surface static pressures have been shown to be in good agreement with test data for a high velocity core nozzle. The equivalent ideal nozzle has also been shown to be a good representation for jets with a relatively low velocity core and for jets originating from a vaned nozzle in evaluating jet-induced flow fields. For the singular case of a low velocity core nozzle, namely a nozzle with a dead air core, and for the vaned nozzle, an alternative procedure has been developed. The internal mixing which takes place in the jet core has been properly accounted for in the equations of motion governing the jet development. Calculations of jet centerlines and induced surface static pressures show good agreement with test data these nozzles.

Ziegler, H.; Woller, P. T.

1973-01-01

7

SYNTHETIC JET THRUST OPTIMIZATION FOR APPLICATION  

E-print Network

of this type of vehicles is adjusted using control surfaces, the magnitude of the available control force1 SYNTHETIC JET THRUST OPTIMIZATION FOR APPLICATION IN UNDERWATER VEHICLES Michael Krieg maneuvering and station keeping of small underwater vehicles. The flow field of such jets are initially

Mohseni, Kamran

8

Electromechanical actuation for thrust vector control applications  

Microsoft Academic Search

At present, actuation systems for the Thrust Vector Control (TVC) for launch vehicles are hydraulic systems. The Advanced Launch System (ALS), a joint initiative between NASA and the Air Force, is a launch vehicle that is designed to be cost effective, highly reliable and operationally efficient with a goal of reducing the cost per pound to orbit. As part of

Mary Ellen Roth

1990-01-01

9

Thrust vector control using electric actuation  

Microsoft Academic Search

Presently, gimbaling of launch vehicle engines for thrust vector control is generally accomplished using a hydraulic system. In the case of the space shuttle solid rocket boosters and main engines, these systems are powered by hydrazine auxiliary power units. Use of electromechanical actuators would provide significant advantages in cost and maintenance. However, present energy source technologies such as batteries are

Robert T. Bechtel; David K. Hall

1995-01-01

10

Thrust vectoring for lateral-directional stability  

NASA Technical Reports Server (NTRS)

The advantages and disadvantages of using thrust vectoring for lateral-directional control and the effects of reducing the tail size of a single-engine aircraft were investigated. The aerodynamic characteristics of the F-16 aircraft were generated by using the Aerodynamic Preliminary Analysis System II panel code. The resulting lateral-directional linear perturbation analysis of a modified F-16 aircraft with various tail sizes and yaw vectoring was performed at several speeds and altitudes to determine the stability and control trends for the aircraft compared to these trends for a baseline aircraft. A study of the paddle-type turning vane thrust vectoring control system as used on the National Aeronautics and Space Administration F/A-18 High Alpha Research Vehicle is also presented.

Peron, Lee R.; Carpenter, Thomas

1992-01-01

11

Thrust vector control using electric actuation  

NASA Astrophysics Data System (ADS)

Presently, gimbaling of launch vehicle engines for thrust vector control is generally accomplished using a hydraulic system. In the case of the space shuttle solid rocket boosters and main engines, these systems are powered by hydrazine auxiliary power units. Use of electromechanical actuators would provide significant advantages in cost and maintenance. However, present energy source technologies such as batteries are heavy to the point of causing significant weight penalties. Utilizing capacitor technology developed by the Auburn University Space Power Institute in collaboration with the Auburn CCDS, Marshall Space Flight Center (MSFC) and Auburn are developing EMA system components with emphasis on high discharge rate energy sources compatible with space shuttle type thrust vector control requirements. Testing has been done at MSFC as part of EMA system tests with loads up to 66000 newtons for pulse times of several seconds. Results show such an approach to be feasible providing a potential for reduced weight and operations costs for new launch vehicles.

Bechtel, Robert T.; Hall, David K.

1995-01-01

12

Fluidic Thrust Vectoring of an Axisymmetric Exhaust Nozzle at Static Conditions  

NASA Technical Reports Server (NTRS)

A sub-scale experimental static investigation of an axisymmetric nozzle with fluidic injection for thrust vectoring was conducted at the NASA Langley Jet Exit Test Facility. Fluidic injection was introduced through flush-mounted injection ports in the divergent section. Geometric variables included injection-port geometry and location. Test conditions included a range of nozzle pressure ratios from 2 to 10 and a range of injection total pressure ratio from no-flow to 1.5. The results indicate that fluidic injection in an axisymmetric nozzle operating at design conditions produced significant thrust-vector angles with less reduction in thrust efficiency than that of a fluidically-vectored rectangular jet. The axisymmetric geometry promoted a pressure relief mechanism around the injection slot, thereby reducing the strength of the oblique shock and the losses associated with it. Injection port geometry had minimal effect on thrust vectoring.

Wing, David J.; Giuliano, Victor J.

1997-01-01

13

Reaction thrust of water jet for conical nozzles  

Microsoft Academic Search

Clear knowledge on the reaction thrust of water jet is valuable for better design of water jet propulsion system. In this\\u000a paper, theoretical, numerical and experimental studies were carried out to investigate the effects of the nozzle geometry\\u000a as well as the inlet conditions on the reaction thrust of water jet. Comparison analyses reveal that the reaction thrust has\\u000a a

Guo-qin Huang; You-sheng Yang; Xiao-hui Li; Yu-quan Zhu

2009-01-01

14

Thrust Vector Control for Nuclear Thermal Rockets  

NASA Technical Reports Server (NTRS)

Future space missions may use Nuclear Thermal Rocket (NTR) stages for human and cargo missions to Mars and other destinations. The vehicles are likely to require engine thrust vector control (TVC) to maintain desired flight trajectories. This paper explores requirements and concepts for TVC systems for representative NTR missions. Requirements for TVC systems were derived using 6 degree-of-freedom models of NTR vehicles. Various flight scenarios were evaluated to determine vehicle attitude control needs and to determine the applicability of TVC. Outputs from the models yielded key characteristics including engine gimbal angles, gimbal rates and gimbal actuator power. Additional factors such as engine thrust variability and engine thrust alignment errors were examined for impacts to gimbal requirements. Various technologies are surveyed for TVC systems for the NTR applications. A key factor in technology selection is the unique radiation environment present in NTR stages. Other considerations including mission duration and thermal environments influence the selection of optimal TVC technologies. Candidate technologies are compared to see which technologies, or combinations of technologies best fit the requirements for selected NTR missions. Representative TVC systems are proposed and key properties such as mass and power requirements are defined. The outputs from this effort can be used to refine NTR system sizing models, providing higher fidelity definition for TVC systems for future studies.

Ensworth, Clinton B. F.

2013-01-01

15

Thrust vector control using electric actuation  

SciTech Connect

Presently, gimbaling of launch vehicle engines for thrust vector control is generally accomplished using a hydraulic system. In the case of the space shuttle solid rocket boosters and main engines, these systems are powered by hydrazine auxiliary power units. Use of electromechanical actuators would provide significant advantages in cost and maintenance. However, present energy source technologies such as batteries are heavy to the point of causing significant weight penalties. Utilizing capacitor technology developed by the Auburn University Space Power Institute in collaboration with the Auburn CCDS, Marshall Space Flight Center (MSFC) and Auburn are developing EMA system components with emphasis on high discharge rate energy sources compatible with space shuttle type thrust vector control requirements. Testing has been done at MSFC as part of EMA system tests with loads up to 66000 newtons for pulse times of several seconds. Results show such an approach to be feasible providing a potential for reduced weight and operations costs for new launch vehicles. {copyright} 1995 {ital American} {ital Institute} {ital of} {ital Physics}

Bechtel, R.T.; Hall, D.K. [Marshall Space Flight Center, Marshall Space Flight Center, Alabama 35812 (United States)

1995-01-25

16

Experimental investigations of thrust vectoring systems for VTOL aircraft  

NASA Technical Reports Server (NTRS)

This paper presents a summary of two technology programs sponsored by NASA to investigate the characteristics of two thrust vectoring schemes for V/STOL aircraft. The operational capability of the VTOL aircraft is dependent on maximum utilization of the installed thrust in both the cruise and powered lift modes of flight. An effective thrust vectoring system on the cruise propulsion unit is therefore essential to provide maximum payload in hover and STOL plus minimum specific fuel consumption in loiter and cruise. Introducing a high by-pass ratio fan system, augmenting the gas generator thrust, as the propulsion system for VTOL aircraft places increased significance on the performance of the relatively short coupled thrust vectoring systems. The two programs discussed herein include both large-scale and small-scale tests of a vectoring hood system with a vented, internal-lip and swivel nozzle systems. These tests indicated that a satisfactory thrust vectoring system can be developed.

Rolls, L. S.; Aoyagi, K.

1977-01-01

17

Electromechanical actuation for thrust vector control applications  

NASA Technical Reports Server (NTRS)

The advanced launch system (ALS), is a launch vehicle that is designed to be cost-effective, highly reliable, and operationally efficient with a goal of reducing the cost per pound to orbit. An electromechanical actuation (EMA) system is being developed as an attractive alternative to the hydraulic systems. The controller will integrate 20 kHz resonant link power management and distribution (PMAD) technology and pulse population modulation (PPM) techniques to implement field-oriented vector control (FOVC) of a new advanced induction motor. The driver and the FOVC will be microprocessor controlled. For increased system reliability, a built-in test (BITE) capability will be included. This involves introducing testability into the design of a system such that testing is calibrated and exercised during the design, manufacturing, maintenance, and prelaunch activities. An actuator will be integrated with the motor controller for performance testing of the EMA thrust vector control (TVC) system. The EMA system and work proposed for the future are discussed.

Roth, Mary Ellen

1990-01-01

18

Static performance investigation of a skewed-throat multiaxis thrust-vectoring nozzle concept  

NASA Technical Reports Server (NTRS)

The static performance of a jet exhaust nozzle which achieves multiaxis thrust vectoring by physically skewing the geometric throat has been characterized in the static test facility of the 16-Foot Transonic Tunnel at NASA Langley Research Center. The nozzle has an asymmetric internal geometry defined by four surfaces: a convergent-divergent upper surface with its ridge perpendicular to the nozzle centerline, a convergent-divergent lower surface with its ridge skewed relative to the nozzle centerline, an outwardly deflected sidewall, and a straight sidewall. The primary goal of the concept is to provide efficient yaw thrust vectoring by forcing the sonic plane (nozzle throat) to form at a yaw angle defined by the skewed ridge of the lower surface contour. A secondary goal is to provide multiaxis thrust vectoring by combining the skewed-throat yaw-vectoring concept with upper and lower pitch flap deflections. The geometric parameters varied in this investigation included lower surface ridge skew angle, nozzle expansion ratio (divergence angle), aspect ratio, pitch flap deflection angle, and sidewall deflection angle. Nozzle pressure ratio was varied from 2 to a high of 11.5 for some configurations. The results of the investigation indicate that efficient, substantial multiaxis thrust vectoring was achieved by the skewed-throat nozzle concept. However, certain control surface deflections destabilized the internal flow field, which resulted in substantial shifts in the position and orientation of the sonic plane and had an adverse effect on thrust-vectoring and weight flow characteristics. By increasing the expansion ratio, the location of the sonic plane was stabilized. The asymmetric design resulted in interdependent pitch and yaw thrust vectoring as well as nonzero thrust-vector angles with undeflected control surfaces. By skewing the ridges of both the upper and lower surface contours, the interdependency between pitch and yaw thrust vectoring may be eliminated and the location of the sonic plane may be further stabilized.

Wing, David J.

1994-01-01

19

Performance characteristics of two multiaxis thrust-vectoring nozzles at Mach numbers up to 1.28  

NASA Technical Reports Server (NTRS)

The thrust-vectoring axisymmetric (VA) nozzle and a spherical convergent flap (SCF) thrust-vectoring nozzle were tested along with a baseline nonvectoring axisymmetric (NVA) nozzle in the Langley 16-Foot Transonic Tunnel at Mach numbers from 0 to 1.28 and nozzle pressure ratios from 1 to 8. Test parameters included geometric yaw vector angle and unvectored divergent flap length. No pitch vectoring was studied. Nozzle drag, thrust minus drag, yaw thrust vector angle, discharge coefficient, and static thrust performance were measured and analyzed, as well as external static pressure distributions. The NVA nozzle and the VA nozzle displayed higher static thrust performance than the SCF nozzle throughout the nozzle pressure ratio (NPR) range tested. The NVA nozzle had higher overall thrust minus drag than the other nozzles throughout the NPR and Mach number ranges tested. The SCF nozzle had the lowest jet-on nozzle drag of the three nozzles throughout the test conditions. The SCF nozzle provided yaw thrust angles that were equal to the geometric angle and constant with NPR. The VA nozzle achieved yaw thrust vector angles that were significantly higher than the geometric angle but not constant with NPR. Nozzle drag generally increased with increases in thrust vectoring for all the nozzles tested.

Wing, David J.; Capone, Francis J.

1993-01-01

20

Jet Propulsion with Special Reference to Thrust Augmenters  

NASA Technical Reports Server (NTRS)

An investigation of the possibility of using thrust augmented jets as prime movers was carried out. The augmentation was to be effected by allowing the jet to mix with the surrounding air in the presence of bodies which deflect the air set in motion by the jet.

Schubauer, G B

1933-01-01

21

Static performance of a cruciform nozzle with multiaxis thrust-vectoring and reverse-thrust capabilities  

NASA Technical Reports Server (NTRS)

A multiaxis thrust vectoring nozzle designed to have equal flow turning capability in pitch and yaw was conceived and experimentally tested for internal, static performance. The cruciform-shaped convergent-divergent nozzle turned the flow for thrust vectoring by deflecting the divergent surfaces of the nozzle, called flaps. Methods for eliminating physical interference between pitch and yaw flaps at the larger multiaxis deflection angles was studied. These methods included restricting the pitch flaps from the path of the yaw flaps and shifting the flow path at the throat off the nozzle centerline to permit larger pitch-flap deflections without interfering with the operation of the yaw flaps. Two flap widths were tested at both dry and afterburning settings. Vertical and reverse thrust configurations at dry power were also tested. Comparison with two dimensional convergent-divergent nozzles showed lower but still competitive thrust performance and thrust vectoring capability.

Wing, David J.; Asbury, Scott C.

1992-01-01

22

Electromechanical actuation for thrust vector control applications  

NASA Technical Reports Server (NTRS)

At present, actuation systems for the Thrust Vector Control (TVC) for launch vehicles are hydraulic systems. The Advanced Launch System (ALS), a joint initiative between NASA and the Air Force, is a launch vehicle that is designed to be cost effective, highly reliable and operationally efficient with a goal of reducing the cost per pound to orbit. As part of this initiative, an electromechanical actuation system is being developed as an attractive alternative to the hydraulic systems used today. NASA-Lewis is developing and demonstrating an Induction Motor Controller Actuation System with a 40 hp peak rating. The controller will integrate 20 kHz resonant link Power Management and Distribution (PMAD) technology and Pulse Population Modulation (PPM) techniques to implement Field Oriented Vector Control (FOVC) of a new advanced induction motor. Through PPM, multiphase variable frequency, variable voltage waveforms can be synthesized from the 20 kHz source. FOVC shows that varying both the voltage and frequency and their ratio (V/F), permits independent control of both torque and speed while operating at maximum efficiency at any point on the torque-speed curve. The driver and the FOVC will be microprocessor controlled. For increased system reliability, a Built-in Test (BITE) capability will be included. This involves introducing testability into the design of a system such that testing is calibrated and exercised during the design, manufacturing, maintenance and prelaunch activities. An actuator will be integrated with the motor controller for performance testing of the EMA TVC system. The design and fabrication of the motor controller is being done by General Dynamics Space Systems Division. The University of Wisconsin-Madison will assist in the design of the advanced induction motor and in the implementation of the FOVC theory. A 75 hp electronically controlled dynamometer will be used to test the motor controller in all four quadrants of operation using flight type control algorithms. Integrated testing of the controller and actuator will be conducted at a facility yet to be named. The EMA system described above is discussed in detail.

Roth, Mary Ellen

1990-01-01

23

Electromechanical actuation for thrust vector control applications  

NASA Astrophysics Data System (ADS)

At present, actuation systems for the Thrust Vector Control (TVC) for launch vehicles are hydraulic systems. The Advanced Launch System (ALS), a joint initiative between NASA and the Air Force, is a launch vehicle that is designed to be cost effective, highly reliable and operationally efficient with a goal of reducing the cost per pound to orbit. As part of this initiative, an electromechanical actuation system is being developed as an attractive alternative to the hydraulic systems used today. NASA-Lewis is developing and demonstrating an Induction Motor Controller Actuation System with a 40 hp peak rating. The controller will integrate 20 kHz resonant link Power Management and Distribution (PMAD) technology and Pulse Population Modulation (PPM) techniques to implement Field Oriented Vector Control (FOVC) of a new advanced induction motor. Through PPM, multiphase variable frequency, variable voltage waveforms can be synthesized from the 20 kHz source. FOVC shows that varying both the voltage and frequency and their ratio (V/F), permits independent control of both torque and speed while operating at maximum efficiency at any point on the torque-speed curve. The driver and the FOVC will be microprocessor controlled. For increased system reliability, a Built-in Test (BITE) capability will be included. This involves introducing testability into the design of a system such that testing is calibrated and exercised during the design, manufacturing, maintenance and prelaunch activities. An actuator will be integrated with the motor controller for performance testing of the EMA TVC system. The design and fabrication of the motor controller is being done by General Dynamics Space Systems Division. The University of Wisconsin-Madison will assist in the design of the advanced induction motor and in the implementation of the FOVC theory. A 75 hp electronically controlled dynamometer will be used to test the motor controller in all four quadrants of operation using flight type control algorithms. Integrated testing of the controller and actuator will be conducted at a facility yet to be named. The EMA system described above is discussed in detail.

Roth, Mary Ellen

24

Feedback control for counterflow thrust vectoring with a turbine engine: Experiment design and robust control design and implementation  

NASA Astrophysics Data System (ADS)

Engineering research over the last few years has successfully demonstrated the potential of thrust vector control using counterflow at conditions up to Mach 2. Flow configurations that include the pitch vectoring of rectangular jets and multi-axis vector control in diamond and axisymmetric nozzle geometries have been studied. Although bistable (on-off) fluid-based control has been around for some time, the present counterflow thrust vector control is unique because proportional and continuous jet response can be achieved in the absence of moving parts, while avoiding jet attachment, which renders most fluidic approaches unacceptable for aircraft and missile control applications. However, before this study, research had been limited to open-loop studies of counterflow thrust vectoring. For practical implementation it was vital that the counterflow scheme be used in conjunction with feedback control. Hence, the focus of this research was to develop and experimentally demonstrate a feedback control design methodology for counterflow thrust vectoring. This research focused on 2-D (pitch) thrust vectoring and addresses four key modeling issues. The first issue is to determine the measured variable to be commanded since the thrust vector angle is not measurable in real time. The second related issue is to determine the static mapping from the thrust vector angle to this measured variable. The third issue is to determine the dynamic relationship between the measured variable and the thrust vector angle. The fourth issue is to develop dynamic models with uncertainty characterizations. The final and main goal was the design and implementation of robust controllers that yield closed-loop systems with fast response times, and avoid overshoot in order to aid in the avoidance of attachment. These controllers should be simple and easy to implement in real applications. Hence, PID design has been chosen. Robust control design is accomplished by using ?1 control theory in conjunction with the Popov-Tsypkin multiplier. The resulting optimization problem was solved using a real coded genetic-algorithm.

Dores, Delfim Zambujo Das

2005-11-01

25

Ground test of the D shaped vented thrust vectoring nozzle  

NASA Technical Reports Server (NTRS)

Static ground tests of a large scale lift/cruise thrust vectoring nozzle were conducted to establish: (1) vectoring performance 'in' and 'out' of ground effect; (2) thrust spoilage capability; (3) compatibility of the nozzle with a turbotip fan; and (4) the nozzle structural temperature distribution. Vectoring performance of a short coupled, vented nozzle design on a large scale, (60%) basis was compared with small scale (4.5%) test nozzle results. The test nozzle was a "boilerplate" model of the MCAIR "D" vented nozzle configured for operation with the LF336/J85 turbotip lift fan system. Calibration of the LF336/J85 test fan with a simple convergent nozzle was performed with four different nozzle exit areas to establish reference thrust, nozzle pressure ratio, and nozzle corrected flow characteristics for comparison with the thrust vectoring nozzle data. Thrust vectoring tests with the 'D' vented nozzle were conducted over the range of vector angles between 0 and 117 deg for several different nozzle exit areas.

Esker, D. W.

1976-01-01

26

Internal performance characteristics of thrust-vectored axisymmetric ejector nozzles  

NASA Technical Reports Server (NTRS)

A series of thrust-vectored axisymmetric ejector nozzles were designed and experimentally tested for internal performance and pumping characteristics at the Langley research center. This study indicated that discontinuities in the performance occurred at low primary nozzle pressure ratios and that these discontinuities were mitigated by decreasing expansion area ratio. The addition of secondary flow increased the performance of the nozzles. The mid-to-high range of secondary flow provided the most overall improvements, and the greatest improvements were seen for the largest ejector area ratio. Thrust vectoring the ejector nozzles caused a reduction in performance and discharge coefficient. With or without secondary flow, the vectored ejector nozzles produced thrust vector angles that were equivalent to or greater than the geometric turning angle. With or without secondary flow, spacing ratio (ejector passage symmetry) had little effect on performance (gross thrust ratio), discharge coefficient, or thrust vector angle. For the unvectored ejectors, a small amount of secondary flow was sufficient to reduce the pressure levels on the shroud to provide cooling, but for the vectored ejector nozzles, a larger amount of secondary air was required to reduce the pressure levels to provide cooling.

Lamb, Milton

1995-01-01

27

Acoustically shielded exhaust system for high thrust jet engines  

NASA Technical Reports Server (NTRS)

A flade exhaust nozzle for a high thrust jet engine is configured to form an acoustic shield around the core engine exhaust flowstream while supplementing engine thrust during all flight conditions, particularly during takeoff. The flade airflow is converted from an annular 360.degree. flowstream to an arcuate flowstream extending around the lower half of the core engine exhaust flowstream so as to suppress exhaust noise directed at the surrounding community.

Carey, John P. (Inventor); Lee, Robert (Inventor); Majjigi, Rudramuni K. (Inventor)

1995-01-01

28

Thrust Vectoring on the NASA F-18 High Alpha Research Vehicle  

NASA Technical Reports Server (NTRS)

Investigations into a multiaxis thrust-vectoring system have been conducted on an F-18 configuration. These investigations include ground-based scale-model tests, ground-based full-scale testing, and flight testing. This thrust-vectoring system has been tested on the NASA F-18 High Alpha Research Vehicle (HARV). The system provides thrust vectoring in pitch and yaw axes. Ground-based subscale test data have been gathered as background to the flight phase of the program. Tests investigated aerodynamic interaction and vane control effectiveness. The ground-based full-scale data were gathered from static engine runs with image analysis to determine relative thrust-vectoring effectiveness. Flight tests have been conducted at the NASA Dryden Flight Research Center. Parameter identification input techniques have been developed. Individual vanes were not directly controlled because of a mixer-predictor function built into the flight control laws. Combined effects of the vanes have been measured in flight and compared to combined effects of the vanes as predicted by the cold-jet test data. Very good agreement has been found in the linearized effectiveness derivatives.

Bowers, Albion H.; Pahle, Joseph W.

1996-01-01

29

Design of an ion thruster movable grid thrust vectoring system  

NASA Astrophysics Data System (ADS)

Several reasons justify the development of an ion propulsion system thrust vectoring system. Spacecraft launched to date have used ion thrusters mounted on gimbals to control the thrust vector within a range of about ±5°. Such devices have large mass and dimensions, hence the need exists for a more compact system, preferably mounted within the thruster itself. Since the 1970s several thrust vectoring systems have been developed, with the translatable accelerator grid electrode being considered the most promising. Laboratory models of this system have already been built and successfully tested, but there is still room for improvement in their mechanical design. This work aims to investigate possibilities of refining the design of such movable grid thrust vectoring systems. Two grid suspension designs and three types of actuators were evaluated. The actuators examined were a micro electromechanical system, a NanoMuscle shape memory alloy actuator and a piezoelectric driver. Criteria used for choosing the best system included mechanical simplicity (use of the fewest mechanical parts), accuracy, power consumption and behaviour in space conditions. Designs of systems using these actuators are proposed. In addition, a mission to Mercury using the system with piezoelectric drivers has been modelled and its performance presented.

Kural, Aleksander; Leveque, Nicolas; Welch, Chris; Wolanski, Piotr

2004-08-01

30

Static internal performance of a two-dimensional convergent nozzle with thrust-vectoring capability up to 60 deg  

NASA Technical Reports Server (NTRS)

An investigation was conducted at wind-off conditions in the static-test facility of the Langley 16-Foot Transonic Tunnel to determine the internal performance characteristics of a two-dimensional convergent nozzle with a thrust-vectoring capability up to 60 deg. Vectoring was accomplished by a downward rotation of a hinged upper convergent flap and a corresponding rotation of a center-pivoted lower convergent flap. The effects of geometric thrust-vector angle and upper-rotating-flap geometry on internal nozzle performance characteristics were investigated. Nozzle pressure ratio was varied from 1.0 (jet off) to approximately 5.0.

Leavitt, L. D.

1985-01-01

31

Conceptual design of a thrust-vectoring tailcone for underwater robotics  

E-print Network

Thrust-vectoring on Autonomous Underwater Vehicles is an appealing directional-control solution because it improves turning radius capabilities. Unfortunately, thrust-vectoring requires the entire propulsion system be ...

Nawrot, Michael T

2012-01-01

32

Static investigation of a two-dimensional convergent-divergent exhaust nozzle with multiaxis thrust-vectoring capability  

NASA Technical Reports Server (NTRS)

An investigation was conducted in the Static Test Facility of the NASA Langley 16-Foot Transonic Tunnel to determine the internal performance of two-dimensional convergent-divergent nozzles designed to have simultaneous pitch and yaw thrust vectoring capability. This concept utilized divergent flap rotation of thrust vectoring in the pitch plane and deflection of flat yaw flaps hinged at the end of the sidewalls for yaw thrust vectoring. The hinge location of the yaw flaps was varied at four positions from the nozzle exit plane to the throat plane. The yaw flaps were designed to contain the flow laterally independent of power setting. In order to eliminate any physical interference between the yaw flap deflected into the exhaust stream and the divergent flaps, the downstream corners of both upper and lower divergent flaps were cut off to allow for up to 30 deg of yaw flap deflection. The impact of varying the nozzle pitch vector angle, throat area, yaw flap hinge location, yaw flap length, and yaw flap deflection angle on nozzle internal performance characteristics, was studied. High-pressure air was used to simulate jet exhaust at nozzle pressure ratios up to 7.0. Static results indicate that configurations with the yaw flap hinge located upstream of the exit plane provide relatively high levels of thrust vectoring efficiency without causing large losses in resultant thrust ratio. Therefore, these configurations represent a viable concept for providing simultaneous pitch and yaw thrust vectoring.

Taylor, John G.

1990-01-01

33

Noise generated by STOL core-jet thrust reversers  

NASA Technical Reports Server (NTRS)

An experimental investigation on the noise generated by target-type thrust reversers is discussed. The experimental data are normalized and scaled up to sizes suitable for reversing the core jets of a 100,000 lb augmentor-wing-type STOL airplane. The scaling calculations yield perceived noise levels well above the 95-PNdB design goal for both sideline and flyover at 500 ft. V-gutter and semicylindrical reversers were tested with a 5.24-cm-diameter circular nozzle, and a semicylindrical reverser was also tested with a 7.78-cm-diameter circular nozzle. The thrust reversers, in addition to being noisier than the nozzle alone, also had a more uniform directivity. The maximum overall sound pressure level and the effective sound power level both varied with sixth power of the nozzle jet velocity.

Stone, J. R.; Gutierrez, O. A.

1972-01-01

34

Static internal performance of single-expansion-ramp nozzles with thrust-vectoring capability up to 60 deg  

NASA Technical Reports Server (NTRS)

An investigation has been conducted at static conditions (wind off) in the static-test facility of the Langley 16-Foot Transonic Tunnel. The effects of geometric thrust-vector angle, sidewall containment, ramp curvature, lower-flap lip angle, and ramp length on the internal performance of nonaxisymmetric single-expansion-ramp nozzles were investigated. Geometric thrust-vector angle was varied from -20 deg. to 60 deg., and nozzle pressure ratio was varied from 1.0 (jet off) to approximately 10.0.

Berrier, B. L.; Leavitt, L. D.

1984-01-01

35

Multiaxis thrust vectoring using axisymmetric nozzles and postexit vanes on an F/A-18 configuration vehicle  

NASA Technical Reports Server (NTRS)

A ground-based investigation was conducted on an operational system of multiaxis thrust vectoring using postexit vanes around an axisymmetric nozzle. This thrust vectoring system will be tested on the NASA F/A-18 High Alpha Research Vehicle (HARV) aircraft. The system provides thrust vectoring capability in both pitch and yaw. Ground based data were gathered from two separate tests at NASA Langley Research Center. The first was a static test in the 16-foot Transonic Tunnel Cold-Jet Facility with a 14.25 percent scale model of the axisymmetric nozzle and the postexit vanes. The second test was conducted in the 30 by 60 foot wind tunnel with a 16 percent F/A-18 complete configuration model. Data from the two sets are being used to develop models of jet plume deflection and thrust loss as a function of vane deflection. In addition, an aerodynamic interaction model based on plume deflection angles will be developed. Results from the scale model nozzle test showed that increased vane deflection caused exhaust plume turning. Aerodynamic interaction effects consisted primarily of favorable interaction of moments and unfavorable interaction of forces caused by the vectored jet plume.

Bowers, Albion H.; Noffz, Gregory K.; Grafton, Sue B.; Mason, Mary L.; Peron, Lee R.

1991-01-01

36

Effect of thrust vectoring and wing maneuver devices on transonic aeropropulsive characteristics of a supersonic fighter  

NASA Technical Reports Server (NTRS)

The aeropropulsive characteristics of an advanced fighter designed for supersonic cruise were determined in the Langley 16-Foot Transonic Tunnel. The objectives of this investigation were to evaluate the interactive effects of thrust vectoring and wing maneuver devices on lift and drag and to determine trim characteristics. The wing maneuver devices consisted of a drooped leading edge and a trailing-edge flap. Thrust vectoring was accomplished with two dimensional (nonaxisymmetric) convergent-divergent nozzles located below the wing in two single-engine podded nacelles. A canard was utilized for trim. Thrust vector angles of 0 deg, 15 deg, and 30 deg were tested in combination with a drooped wing leading edge and with wing trailing-edge flap deflections up to 30 deg. This investigation was conducted at Mach numbers from 0.60 to 1.20, at angles of attack from 0 deg to 20 deg, and at nozzle pressure ratios from about 1 (jet off) to 10. Reynolds number based on mean aerodynamic chord varied from 9.24 x 10 to the 6th to 10.56 x 10 to the 6th.

Capone, F. J.; Reubush, D. E.

1983-01-01

37

Evaluation of dual flow thrust vector nozzles with exhaust stream impingement  

NASA Technical Reports Server (NTRS)

To supplement previous work performed by NASA, a cold-jet facility was established at the California Polytechnic State University, San Luis Obispo campus. The purpose of this facility is to continue the studies of cold flow multiaxis thrust vectoring conducted at the NASA Langley Research Center. A single nozzle test apparatus was completed and is presently operational. Included are the results of the single flow test envelope that was requested by NASA personnel. Details about the test apparatus are included in the Cal Poly Semi-Annual Progress report.

Carpenter, Thomas W.; Dobbins, Sean; Vaccarezza, Steven

1992-01-01

38

Noise generated by STOL core-jet thrust reversers.  

NASA Technical Reports Server (NTRS)

This paper summarizes the results of an experimental investigation on the noise generated by target-type thrust reversers. The experimental data are normalized and scaled up to sizes suitable for reversing the core jets of a 45,400-kg augmentor-wing-type STOL airplane. The scaling calculatings yield perceived noise levels well above the 95-PNdB design goal for both sideline and flyover at 152.5 m. V-gutter and semicylindrical reversers were tested with a 5.24-cm-diameter circular nozzle, and a semicylindrical reverser was also tested with a 7.78-cm-diameter circular nozzle. Other test variables were the spacing between nozzle and reverser, reverser orientation, and nozzle pressure ratio. The thrust reversers, in addition to being noisier than the nozzle alone, also had a more uniform directivity.

Stone, J. R.; Gutierrez, O. A.

1972-01-01

39

Design of high power electromechanical actuator for thrust vector control  

NASA Technical Reports Server (NTRS)

NASA-Marshall has undertaken the development of electromechanical actuators (EMAs) for thrust vector control (TVC) augmentation system implementation. The TVC EMA presented has as its major components two three-phase brushless dc motors, a two-pass gear-reduction system, and a roller screw for rotary-to-linear motion conversion. System control is furnished by a solid-state electronic controller and power supply; a pair of resolvers deliver position feedback to the controller, such that precise positioning is achieved. Peformance comparisons have been conducted between the EMA and comparable-performance hydraulic systems applicable to TVCs.

Cowan, J. R.; Myers, W. N.

1991-01-01

40

Attitude Control for an Aero-Vehicle Using Vector Thrusting and Variable Speed Control Moment Gyros  

NASA Technical Reports Server (NTRS)

Stabilization of passively unstable thrust-levitated vehicles can require significant control inputs. Although thrust vectoring is a straightforward choice for realizing these inputs, this may lead to difficulties discussed in the paper. This paper examines supplementing thrust vectoring with Variable-Speed Control Moment Gyroscopes (VSCMGs). The paper describes how to allocate VSCMGs and the vectored thrust mechanism for attitude stabilization in frequency domain and also shows trade-off between vectored thrust and VSCMGs. Using an H2 control synthesis methodology in LMI optimization, a feedback control law is designed for a thrust-levitated research vehicle and is simulated with the full nonlinear model. It is demonstrated that VSCMGs can reduce the use of vectored thrust variation for stabilizing the hovering platform in the presence of strong wind gusts.

Shin, Jong-Yeob; Lim, K. B.; Moerder, D. D.

2005-01-01

41

Multiaxis Thrust-Vectoring Characteristics of a Model Representative of the F-18 High-Alpha Research Vehicle at Angles of Attack From 0 deg to 70 deg  

NASA Technical Reports Server (NTRS)

An investigation was conducted in the Langley 16-Foot Transonic Tunnel to determine the multiaxis thrust-vectoring characteristics of the F-18 High-Alpha Research Vehicle (HARV). A wingtip supported, partially metric, 0.10-scale jet-effects model of an F-18 prototype aircraft was modified with hardware to simulate the thrust-vectoring control system of the HARV. Testing was conducted at free-stream Mach numbers ranging from 0.30 to 0.70, at angles of attack from O' to 70', and at nozzle pressure ratios from 1.0 to approximately 5.0. Results indicate that the thrust-vectoring control system of the HARV can successfully generate multiaxis thrust-vectoring forces and moments. During vectoring, resultant thrust vector angles were always less than the corresponding geometric vane deflection angle and were accompanied by large thrust losses. Significant external flow effects that were dependent on Mach number and angle of attack were noted during vectoring operation. Comparisons of the aerodynamic and propulsive control capabilities of the HARV configuration indicate that substantial gains in controllability are provided by the multiaxis thrust-vectoring control system.

Asbury, Scott C.; Capone, Francis J.

1995-01-01

42

Design and test of electromechanical actuators for thrust vector control  

NASA Technical Reports Server (NTRS)

New control mechanisms technologies are currently being explored to provide alternatives to hydraulic thrust vector control (TVC) actuation systems. For many years engineers have been encouraging the investigation of electromechanical actuators (EMA) to take the place of hydraulics for spacecraft control/gimballing systems. The rationale is to deliver a lighter, cleaner, safer, more easily maintained, as well as energy efficient space vehicle. In light of this continued concern to improve the TVC system, the Propulsion Laboratory at the NASA George C. Marshall Space Flight Center (MSFC) is involved in a program to develop electromechanical actuators for the purpose of testing and TVC system implementation. Through this effort, an electromechanical thrust vector control actuator has been designed and assembled. The design consists of the following major components: Two three-phase brushless dc motors, a two pass gear reduction system, and a roller screw, which converts rotational input into linear output. System control is provided by a solid-state electronic controller and power supply. A pair of resolvers and associated electronics deliver position feedback to the controller such that precise positioning is achieved. Testing and evaluation is currently in progress. Goals focus on performance comparisons between EMA's and similar hydraulic systems.

Cowan, J. R.; Weir, Rae Ann

1993-01-01

43

Attitude control of a spinning rocket via thrust vectoring  

SciTech Connect

Two controllers are developed to provide attitude control of a spinning rocket that has a thrust vectoring capability. The first controller has a single-input/single-output design that ignores the gyroscopic coupling between the control channels. The second controller has a multi-input/multi-output structure that is specifically intended to account for the gyroscopic coupling effects. A performance comparison between the two approached is conducted for a range of roll rates. Each controller is tested for the ability to track step commands, and for the amount of coupling impurity. Both controllers are developed via a linear-quadratic-regulator synthesis procedure, which is motivated by the multi-input/multi-output nature of second controller. Time responses and a singular value analysis are used to evaluate controller performance. This paper describes the development and comparison of two controllers that are designed to provide attitude control of a spinning rocket that is equipped with thrust vector control. 12 refs., 13 figs., 2 tabs.

White, J.E.

1990-12-19

44

Preliminary design study of a lateral-directional control system using thrust vectoring  

NASA Technical Reports Server (NTRS)

A preliminary design of a lateral-directional control system for a fighter airplane capable of controlled operation at extreme angles of attack is developed. The subject airplane is representative of a modern twin-engine high-performance jet fighter, is equipped with ailerons, rudder, and independent horizontal-tail surfaces. Idealized bidirectional thrust-vectoring engine nozzles are appended to the mathematic model of the airplane to provide additional control moments. Optimal schedules for lateral and directional pseudo control variables are calculated. Use of pseudo controls results in coordinated operation of the aerodynamic and thrust-vectoring controls with minimum coupling between the lateral and directional airplane dynamics. Linear quadratic regulator designs are used to specify a preliminary flight control system to improve the stability and response characteristics of the airplane. Simulated responses to step pilot control inputs are stable and well behaved. For lateral stick deflections, peak stability axis roll rates are between 1.25 and 1.60 rad/sec over an angle-of-attack range of 10 deg to 70 deg. For rudder pedal deflections, the roll rates accompanying the sideslip responses can be arrested by small lateral stick motions.

Lallman, F. J.

1985-01-01

45

PAB3D Simulations of a Nozzle with Fluidic Injection for Yaw Thrust-Vector Control  

NASA Technical Reports Server (NTRS)

An experimental and computational study was conducted on an exhaust nozzle with fluidic injection for yaw thrust-vector control. The nozzle concept was tested experimentally in the NASA Langley Jet Exit Test Facility (JETF) at nozzle pressure ratios up to 4 and secondary fluidic injection flow rates up to 15 percent of the primary flow rate. Although many injection-port geometries and two nozzle planforms (symmetric and asymmetric) were tested experimentally, this paper focuses on the computational results of the more successful asymmetric planform with a slot injection port. This nozzle concept was simulated with the Navier-Stokes flow solver, PAB3D, invoking the Shih, Zhu, and Lumley algebraic Reynolds stress turbulence model (ASM) at nozzle pressure ratios (NPRs) of 2,3, and 4 with secondary to primary injection flow rates (w(sub s)/w(sub p)) of 0, 2, 7 and 10 percent.

Deere, Karen A.

1998-01-01

46

Static performance of an axisymmetric nozzle with post-exit vanes for multiaxis thrust vectoring  

NASA Technical Reports Server (NTRS)

An investigation was conducted in the static test facility of the Langley 16-Foot Transonic Tunnel to determine the flow-turning capability and the nozzle internal performance of an axisymmetric convergent-divergent nozzle with post-exit vanes installed for multiaxis thrust vectoring. The effects of vane curvature, vane location relative to the nozzle exit, number of vanes, and vane deflection angle were determined. A comparison of the post-exit-vane thrust-vectoring concept with other thrust-vectoring concepts is provided. All tests were conducted with no external flow, and nozzle pressure ratio was varied from 1.6 to 6.0.

Berrier, Bobby L.; Mason, Mary L.

1988-01-01

47

An experimental investigation of thrust vectoring two-dimensional convergent-divergent nozzles installed in a twin-engine fighter model at high angles of attack  

NASA Technical Reports Server (NTRS)

An investigation was conducted in the Langley 16-Foot Transonic Tunnel to determine thrust vectoring capability of subscale 2-D convergent-divergent exhaust nozzles installed on a twin engine general research fighter model. Pitch thrust vectoring was accomplished by downward rotation of nozzle upper and lower flaps. The effects of nozzle sidewall cutback were studied for both unvectored and pitch vectored nozzles. A single cutback sidewall was employed for yaw thrust vectoring. This investigation was conducted at Mach numbers ranging from 0 to 1.20 and at angles of attack from -2 to 35 deg. High pressure air was used to simulate jet exhaust and provide values of nozzle pressure ratio up to 9.

Capone, Francis J.; Mason, Mary L.; Leavitt, Laurence D.

1990-01-01

48

Static internal performance of single expansion-ramp nozzles with thrust vectoring and reversing  

NASA Technical Reports Server (NTRS)

The effects of geometric design parameters on the internal performance of nonaxisymmetric single expansion-ramp nozzles were investigated at nozzle pressure ratios up to approximately 10. Forward-flight (cruise), vectored-thrust, and reversed-thrust nozzle operating modes were investigated.

Re, R. J.; Berrier, B. L.

1982-01-01

49

Static Investigation of a Multiaxis Thrust-Vectoring Nozzle With Variable Internal Contouring Ability  

NASA Technical Reports Server (NTRS)

The thrust efficiency and vectoring performance of a convergent-divergent nozzle were investigated at static conditions in the model preparation area of the Langley 16-Foot Transonic Tunnel. The diamond-shaped nozzle was capable of varying the internal contour of each quadrant individually by using cam mechanisms and retractable drawers to produce pitch and yaw thrust vectoring. Pitch thrust vectoring was achieved by either retracting the lower drawers to incline the throat or varying the internal flow-path contours to incline the throat. Yaw thrust vectoring was achieved by reducing flow area left of the nozzle centerline and increasing flow area right of the nozzle centerline; a skewed throat deflected the flow in the lateral direction.

Wing, David J.; Mills, Charles T. L.; Mason, Mary L.

1997-01-01

50

Experimental Investigation of Unsteady Thrust Augmentation Using a Speaker-Driven Jet  

NASA Technical Reports Server (NTRS)

An experimental investigation is described in which a simple speaker-driven jet was used as a pulsed thrust source (driver) for an ejector configuration. The objectives of the investigation were twofold. The first was to expand the experimental body of evidence showing that an unsteady thrust source, combined with a properly sized ejector generally yields higher thrust augmentation values than a similarly sized, steady driver of equivalent thrust. The second objective was to identify characteristics of the unsteady driver that may be useful for sizing ejectors, and for predicting the thrust augmentation levels that may be achieved. The speaker-driven jet provided a convenient source for the investigation because it is entirely unsteady (i.e., it has no mean velocity component) and because relevant parameters such as frequency, time-averaged thrust, and diameter are easily variable. The experimental setup will be described, as will the two main measurements techniques employed. These are thrust and digital particle imaging velocimetry of the driver. It will be shown that thrust augmentation values as high as 1.8 were obtained, that the diameter of the best ejector scaled with the dimensions of the emitted vortex, and that the so-called formation time serves as a useful dimensionless parameter by which to characterize the jet and predict performance.

Paxson, Daniel E.; Wernet, Mark P.; John, Wentworth T.

2007-01-01

51

Static internal performance of an axisymmetric nozzle with multiaxis thrust-vectoring capability  

NASA Technical Reports Server (NTRS)

An investigation was conducted in the static test facility of the Langley 16 Foot Transonic Tunnel in order to determine the internal performance characteristics of a multiaxis thrust vectoring axisymmetric nozzle. Thrust vectoring for this nozzle was achieved by deflection of only the divergent section of this nozzle. The effects of nozzle power setting and divergent flap length were studied at nozzle deflection angles of 0 to 30 at nozzle pressure ratios up to 8.0.

Carson, George T., Jr.; Capone, Francis J.

1991-01-01

52

Static calibration of a two-dimensional wedge nozzle with thrust vectoring and spanwise blowing  

NASA Technical Reports Server (NTRS)

The results of a static calibration of the two dimensional wedge nozzles on a STOL configuration of a large-scale fighter model are reported. These nozzles internally turn the efflux produced by two turbojets down 25 degrees and exhaust it over the deflected trailing edge of the wing. This arrangement provides direct thrust lift, enhances wing lift by producting supercirculation, and provides thrust vectoring by varying the deflection of the wing's trailing edge. The thrust is vectored from 10 deg to 38 deg. This system was calibrated with spanwise blowing for augmentation of the leading-edge vortex. When 16% of the turbojet efflux is blown spanwise, the thrust recovered is 92% of the thrust produced when the total efflux is exhausted longitudinally.

Harris, M. J.; Falarski, M. D.

1980-01-01

53

Analysis of Thrust Vectoring Capabilities for the Jupiter Icy Moons Orbiter  

NASA Technical Reports Server (NTRS)

A strategy to mitigate the impact of the trajectory design of the Jupiter Icy Moons Orbiter (JIMO) on the attitude control design is described in this paper. This paper shows how the thrust vectoring control torques, i.e. the torques required to steer the vehicle, depend on various parameters (thrust magnitude, thrust pod articulation angles, and thrust moment arms). Rather than using the entire reaction control system (RCS) system to steer the spacecraft, we investigate the potential utilization of only thrust vectoring of the main ion engines for the required attitude control to follow the representative trajectory. This study has identified some segments of the representative trajectory where the required control torque may exceed the designed ion engine capability, and how the proposed mitigation strategy succeeds in reducing the attitude control torques to within the existing capability.

Quadrelli, Marco B .; Gromov, Konstantin; Murray, Emmanuell

2005-01-01

54

Static Thrust and Vectoring Performance of a Spherical Convergent Flap Nozzle with a Nonrectangular Divergent Duct  

NASA Technical Reports Server (NTRS)

The static internal performance of a multiaxis-thrust-vectoring, spherical convergent flap (SCF) nozzle with a non-rectangular divergent duct was obtained in the model preparation area of the Langley 16-Foot Transonic Tunnel. Duct cross sections of hexagonal and bowtie shapes were tested. Additional geometric parameters included throat area (power setting), pitch flap deflection angle, and yaw gimbal angle. Nozzle pressure ratio was varied from 2 to 12 for dry power configurations and from 2 to 6 for afterburning power configurations. Approximately a 1-percent loss in thrust efficiency from SCF nozzles with a rectangular divergent duct was incurred as a result of internal oblique shocks in the flow field. The internal oblique shocks were the result of cross flow generated by the vee-shaped geometric throat. The hexagonal and bowtie nozzles had mirror-imaged flow fields and therefore similar thrust performance. Thrust vectoring was not hampered by the three-dimensional internal geometry of the nozzles. Flow visualization indicates pitch thrust-vector angles larger than 10' may be achievable with minimal adverse effect on or a possible gain in resultant thrust efficiency as compared with the performance at a pitch thrust-vector angle of 10 deg.

Wing, David J.

1998-01-01

55

Multiaxis control power from thrust vectoring for a supersonic fighter aircraft model at Mach 0.20 to 2.47  

NASA Technical Reports Server (NTRS)

The aeropropulsive characteristics of an advanced twin-engine fighter aircraft designed for supersonic cruise have been studied in the Langley 16-Foot Tansonic Tunnel and the Lewis 10- by 10-Foot Supersonic Tunnel. The objective was to determine multiaxis control-power characteristics from thrust vectoring. A two-dimensional convergent-divergent nozzle was designed to provide yaw vector angles of 0, -10, and -20 deg combined with geometric pitch vector angles of 0 and 15 deg. Yaw thrust vectoring was provided by yaw flaps located in the nozzle sidewalls. Roll control was obtained from differential pitch vectoring. This investigation was conducted at Mach numbers from 0.20 to 2.47. Angle of attack was varied from 0 to about 19 deg, and nozzle pressure ratio was varied from about 1 (jet off) to 28, depending on Mach number. Increments in force or moment coefficient that result from pitch or yaw thrust vectoring remain essentially constant over the entire angle-of-attack range of all Mach numbers tested. There was no effect of pitch vectoring on the lateral aerodynamic forces and moments and only very small effects of yaw vectoring on the longitudinal aerodynamic forces and moments. This result indicates little cross-coupling of control forces and moments for combined pitch-yaw vectoring.

Capone, Francis J.; Bare, E. Ann

1987-01-01

56

Thrust-induced effects on subsonic longitudinal aerodynamic characteristics of a vectored-engine-over-wing configuration  

NASA Technical Reports Server (NTRS)

An investigation was conducted in the Langley 4 by 7 Meter Tunnel of the thrust induced effects on the longitudinal aerodynamic characteristics of a vectored-engine-over-wing fighter aircraft. The investigation was conducted at Mach numbers from 0.14 to 0.17 over an angle-of-attack range from -2 deg to 26 deg. The major model variables were the spanwise blowing nozzle sweep angle and main nozzle vector angle along with trailing edge, flap deflections. The overall thrust coefficient (main and spanwise nozzles) was varied from 0 (jet off) to 2.0. The results indicate that the thrust-induced effects from the main nozzle alone were small and mainly due to boundary-layer control affecting a small area behind the nozzle. When the spanwise blowing nozzles were included, the induced effects were larger than the main nozzle alone and were due to both boundary layer control and induced circulation lift. No leading edge vortex effects were evident.

Quinto, P. F.; Paulson, J. W., Jr.

1983-01-01

57

Experimental and Computational Investigation of Multiple Injection Ports in a Convergent-Divergent Nozzle for Fluidic Thrust Vectoring  

NASA Technical Reports Server (NTRS)

A computational and experimental study was conducted to investigate the effects of multiple injection ports in a two-dimensional, convergent-divergent nozzle, for fluidic thrust vectoring. The concept of multiple injection ports was conceived to enhance the thrust vectoring capability of a convergent-divergent nozzle over that of a single injection port without increasing the secondary mass flow rate requirements. The experimental study was conducted at static conditions in the Jet Exit Test Facility of the 16-Foot Transonic Tunnel Complex at NASA Langley Research Center. Internal nozzle performance was obtained at nozzle pressure ratios up to 10 with secondary nozzle pressure ratios up to 1 for five configurations. The computational study was conducted using the Reynolds Averaged Navier-Stokes computational fluid dynamics code PAB3D with two-equation turbulence closure and linear Reynolds stress modeling. Internal nozzle performance was predicted for nozzle pressure ratios up to 10 with a secondary nozzle pressure ratio of 0.7 for two configurations. Results from the experimental study indicate a benefit to multiple injection ports in a convergent-divergent nozzle. In general, increasing the number of injection ports from one to two increased the pitch thrust vectoring capability without any thrust performance penalties at nozzle pressure ratios less than 4 with high secondary pressure ratios. Results from the computational study are in excellent agreement with experimental results and validates PAB3D as a tool for predicting internal nozzle performance of a two dimensional, convergent-divergent nozzle with multiple injection ports.

Waithe, Kenrick A.; Deere, Karen A.

2003-01-01

58

Developmental Testing of Electric Thrust Vector Control Systems for Manned Launch Vehicle Applications  

NASA Technical Reports Server (NTRS)

This paper describes recent developmental testing to verify the integration of a developmental electromechanical actuator (EMA) with high rate lithium ion batteries and a cross platform extensible controller. Testing was performed at the Thrust Vector Control Research, Development and Qualification Laboratory at the NASA George C. Marshall Space Flight Center. Electric Thrust Vector Control (ETVC) systems like the EMA may significantly reduce recurring launch costs and complexity compared to heritage systems. Electric actuator mechanisms and control requirements across dissimilar platforms are also discussed with a focus on the similarities leveraged and differences overcome by the cross platform extensible common controller architecture.

Bates, Lisa B.; Young, David T.

2012-01-01

59

Optimal Thrust Characteristics of a Synthetic Jet Actuator for Application in Low Speed  

E-print Network

actuators are pro- posed for low speed maneuvering and station keeping of small underwater vehicles with minimal energy. However, since the trajectory of this type of vehicles is adjusted using control surfacesOptimal Thrust Characteristics of a Synthetic Jet Actuator for Application in Low Speed Maneuvering

Mohseni, Kamran

60

Multiaxis aircraft control power from thrust vectoring at high angles of attack  

NASA Technical Reports Server (NTRS)

Extensive research programs conducted at the Langley Research Center have shown that thrust vectoring can be provided by multifunction (nonaxisymmetric) nozzles. Most of this research has been conducted on pitch vectoring at both static and forward flight conditions. Recent efforts have been aimed at evaluating yaw vectoring concepts at static (wind off) conditions. This paper summarizes results for three different twin-engine fighter configurations tested over a Mach number range of 0.15 to 2.47 at angles of attack up to 35 deg. The objective of these investigations was to determine the multiaxis control power characteristics provided by thrust vectoring. All three configurations employed two-dimensional convergent-divergent nozzles which provided pitch vectoring by differential deflection of the upper and lower nozzle divergent flaps. Three different means of yaw vectoring were tested: (1) a translating nozzle sidewall; (2) yaw flaps located in the nozzle sidewalls; and (3) canted nozzles. These investigations were conducted in the Langley 16-Foot Transonic Tunnel and the Lewis 10x10-Foot Supersonic Tunnel. Longitudinal and direction control power from thrust vectoring was greater than that provided by aerodynamic control effectors at low speed or at high angles of attack.

Capone, F. J.; Mason, M. L.

1986-01-01

61

NLO Vector Boson Production With Light Jets  

SciTech Connect

In this contribution we present recent progress in the computation of next-to-leading order (NLO) QCD corrections for the production of an electroweak vector boson in association with jets at hadron colliders. We focus on results obtained using the virtual matrix element library BlackHat in conjunction with SHERPA, focusing on results relevant to understanding the background to top production. The production of a vector boson in association with several jets at the Large Hadron Collider (LHC) is an important background for other Standard Model processes as well as new physics signals. In particular, the production of a W boson in association with many jets is an important background for processes involving one or more top quarks. Precise predictions for the backgrounds are crucial to measurement of top-quark processes. Vector boson production in association with multiple jets is also a very important background for many SUSY searches, as it mimics the signatures of many typical decay chains. Here we will discuss how polarization information can be used as an additional handle to differentiate top pair production from 'prompt' W-boson production. More generally, ratios of observables, for example for events containing a W boson versus those containing a Z boson, are expected to be better-behaved as many uncertainties cancel in such ratios. Precise calculation of ratios, along with measurement of one of the two processes in the ratio, can be used in data-driven techniques for estimating backgrounds.

Bern, Z.; Diana, G.; Dixon, L.J.; Febres Cordero, F.; Forde, D.; Gleisberg, T.; Hoeche, S.; Ita, H.; Kosower, D.A.; Maitre, D.; Ozeren, K.

2012-02-15

62

Mixing and Noise Benefit Versus Thrust Penalty in Supersonic Jets Using Impingement Tones  

NASA Technical Reports Server (NTRS)

This paper reports the results of an experimental investigation on the effect of impingement tones generated by obstacles of various geometries on the spreading of a supersonic jet flow. A rectangular supersonic jet was produced using a convergent-divergent nozzle that was operated near its design point (with shocks minimized). The immersion of obstacles in the flow produced an intense impingement tone which then propagated upstream (as feedback) to the jet lip and excited the antisymmetric hydrodynamic mode in the jet, thus setting up a resonant self-sustaining loop. The violent flapping motion of the jet due to excitation of the antisymmetric mode, combined with the unsteady wakes of the obstacles, produced large changes in jet mixing. It was possible to control the frequency and amplitude of the impingement tone excitation by varying the nozzle-to-obstacle distance and the obstacle immersion. By proper shaping of the obstacles it was possible to reduce the thrust penalty significantly.

Raman, Ganesh; Rice, Edward J.

1994-01-01

63

Aeroservoelastic Modeling and Validation of a Thrust-Vectoring F/A-18 Aircraft  

NASA Technical Reports Server (NTRS)

An F/A-18 aircraft was modified to perform flight research at high angles of attack (AOA) using thrust vectoring and advanced control law concepts for agility and performance enhancement and to provide a testbed for the computational fluid dynamics community. Aeroservoelastic (ASE) characteristics had changed considerably from the baseline F/A-18 aircraft because of structural and flight control system amendments, so analyses and flight tests were performed to verify structural stability at high AOA. Detailed actuator models that consider the physical, electrical, and mechanical elements of actuation and its installation on the airframe were employed in the analysis to accurately model the coupled dynamics of the airframe, actuators, and control surfaces. This report describes the ASE modeling procedure, ground test validation, flight test clearance, and test data analysis for the reconfigured F/A-18 aircraft. Multivariable ASE stability margins are calculated from flight data and compared to analytical margins. Because this thrust-vectoring configuration uses exhaust vanes to vector the thrust, the modeling issues are nearly identical for modem multi-axis nozzle configurations. This report correlates analysis results with flight test data and makes observations concerning the application of the linear predictions to thrust-vectoring and high-AOA flight.

Brenner, Martin J.

1996-01-01

64

Modeling and Thrust Optimization of a Bio-Inspired Pulsatile Jet Thruster  

NASA Astrophysics Data System (ADS)

A new type of thruster technology offers promising low speed maneuvering capabilities for underwater vehicles. Similar to the natural locomotion of squid and jellyfish the thruster successively forces fluid jets in and out of a small internal cavity. We investigate several properties of squid and jellyfish locomotion to drive the thruster design including actuation of nozzle geometry and vortex ring thrust augmentation. The thrusters are compact with no extruding components to negatively impact the vehicle's drag. These devices have thrust rise-times orders of magnitude faster than those reported for typical propeller thrusters, making them an attractive option for high accuracy underwater vehicle maneuvering. The dynamics of starting jet circulation, impulse, and kinetic energy are derived in terms of kinematics at the entrance boundary of a semi-infinite domain, specifically identifying the effect of a non-parallel incoming flow. A model for pressure at the nozzle is derived without the typical reliance on a predetermined potential function, making it a powerful tool for modeling any jet flow. Jets are created from multiple nozzle configurations to validate these models, and velocity and vorticity fields are determined using DPIV techniques. A converging starting jet resulted in circulation 90--100%, impulse 70--75%, and energy 105--135% larger than a parallel starting jet with identical volume flux and piston velocity, depending on the stroke ratio. The new model is a much better predictor of the jet properties than the standard 1D slug model. A simplified thrust model, was derived to describe the high frequency thruster characteristics. This model accurately predicts the average thrust, measured directly, for stroke ratios up to a critical value where the leading vortex ring separates from the remainder of the shear flow. A new model predicting the vortex ring pinch-off process is developed based on characteristic centerline velocities. The vortex ring pinch-off is coincides with this velocity criterion, for all cases tested. Piston velocity program and nozzle radius are optimized with respect to average thrust, and a quantity similar to propulsive efficiency. The average thrust is maximized by a critical nozzle radius. An approximate linear time-invariant (LTI) model of the thruster vehicle system was derived which categorizes maneuvers into different characteristic regimes. Initial thruster testing showed that open and closed loop frequency response were sufficiently approximated by the LTI model, and that the thruster is ideally suited for small scale high accuracy maneuvers.

Krieg, Michael W.

65

Thrust shock vector control of an axisymmetric conical supersonic nozzle via secondary transverse gas injection  

NASA Astrophysics Data System (ADS)

Transverse secondary gas injection into the supersonic flow of an axisymmetric convergent-divergent nozzle is investigated to describe the effects of the fluidic thrust vectoring within the framework of a small satellite launcher. Cold-flow dry-air experiments are performed in a supersonic wind tunnel using two identical supersonic conical nozzles with the different transverse injection port positions. The complex three-dimensional flow field generated by the supersonic cross-flows in these test nozzles was examined. Valuable experimental data were confronted and compared with the results obtained from the numerical simulations. Different nozzle models are numerically simulated under experimental conditions and then further investigated to determine which parameters significantly affect thrust vectoring. Effects which characterize the nozzle and thrust vectoring performances are established. The results indicate that with moderate secondary to primary mass flow rate ratios, ranging around 5 %, it is possible to achieve pertinent vector side forces. It is also revealed that injector positioning and geometry have a strong effect on the shock vector control system and nozzle performances.

Zmijanovic, V.; Lago, V.; Sellam, M.; Chpoun, A.

2014-01-01

66

Static internal performance of a single expansion ramp nozzle with multiaxis thrust vectoring capability  

NASA Technical Reports Server (NTRS)

An investigation was conducted at static conditions in order to determine the internal performance characteristics of a multiaxis thrust vectoring single expansion ramp nozzle. Yaw vectoring was achieved by deflecting yaw flaps in the nozzle sidewall into the nozzle exhaust flow. In order to eliminate any physical interference between the variable angle yaw flap deflected into the exhaust flow and the nozzle upper ramp and lower flap which were deflected for pitch vectoring, the downstream corners of both the nozzle ramp and lower flap were cut off to allow for up to 30 deg of yaw vectoring. The effects of nozzle upper ramp and lower flap cutout, yaw flap hinge line location and hinge inclination angle, sidewall containment, geometric pitch vector angle, and geometric yaw vector angle were studied. This investigation was conducted in the static-test facility of the Langley 16-Foot Transonic Tunnel at nozzle pressure ratios up to 8.0.

Capone, Francis J.; Schirmer, Alberto W.

1993-01-01

67

Analysis of the thrust characteristics of jet nozzles designed by various methods  

Microsoft Academic Search

A comparative numerical analysis of the thrust characteristics of axisymmetric jet nozzles designed by various methods is\\u000a carried out. “Extremal“ nozzles designed by variational methods in the absence\\/presence of internal shocks (I), so-called\\u000a “truncated“ nozzles with a uniform characteristic (II), and nozzles designed by the method of conjugate circular arcs (III)\\u000a are considered. A comparison is carried out for both

L. E. Sternin

2000-01-01

68

MODEL PREDICTIVE CONTROL OF A THRUST-VECTORED FLIGHT CONTROL EXPERIMENT  

Microsoft Academic Search

Model predictive control (MPC) is applied to the Caltech ducted fan, a thrust-vectored ?ight experiment. A real-time trajectory generation software based on spline theory and sequential quadratic programming is used to implement the MPC controllers. Timing issues related to the computation and implementation of repeatedly updated optimal trajectories are discussed. Results show computational speeds greater than 10 Hz, 2.5 times

William B. Dunbar; Mark B. Milam; Ryan Franz; Richard M. Murray

2002-01-01

69

Design and test of a high power electromechanical actuator for thrust vector control  

NASA Technical Reports Server (NTRS)

NASA-Marshall is involved in the development of electromechanical actuators (EMA) for thrust-vector control (TVC) system testing and implementation in spacecraft control/gimballing systems, with a view to the replacement of hydraulic hardware. TVC system control is furnished by solid state controllers and power supplies; a pair of resolvers supply position feedback to the controller for precise positioning. Performance comparisons between EMA and hydraulic TVC systems are performed.

Cowan, J. R.; Myers, W. N.

1992-01-01

70

Dryden/Edwards 1994 Thrust-Vectoring Aircraft Fleet - F-18 HARV, X-31, F-16 MATV  

NASA Technical Reports Server (NTRS)

The three thrust-vectoring aircraft at Edwards, California, each capable of flying at extreme angles of attack, cruise over the California desert in formation during flight in March 1994. They are, from left, NASA's F-18 High Alpha Research Vehicle (HARV), flown by the NASA Dryden Flight Research Center; the X-31, flown by the X-31 International Test Organization (ITO) at Dryden; and the Air Force F-16 Multi-Axis Thrust Vectoring (MATV) aircraft. All three aircraft were flown in different programs and were developed independently. The NASA F-18 HARV was a testbed to produce aerodynamic data at high angles of attack to validate computer codes and wind tunnel research. The X-31 was used to study thrust vectoring to enhance close-in air combat maneuvering, while the F-16 MATV was a demonstration of how thrust vectoring could be applied to operational aircraft.

1994-01-01

71

An experimental study of blowdown thrust and jet forces for a pipe under boiling water reactor loss of coolant accident conditions  

SciTech Connect

Blowdown thrust and jet impingement forces are simultaneously examined in jet discharge tests relating to an instantaneous pipe rupture accident. Tests were performed with a 6-in. pipe under boiling water reactor loss of coolant accident conditions. The initial pressure of the hot saturated water was 6.86 MPa. The time history of the blowdown thrust force just after the break, the jet thrust parameter of the pipe, the jet impingement force, the pressure and temperature distributions of the impinging jet, and the relationship between the thermal-hydraulic quantities and the thrust forces are examined.

Yano, T.; Isozaki, T.; Kato, R.; Kurihara, R.; Miyazaki, N.; Miyazono, S.

1984-11-01

72

Linear Test Bed. Volume 2: Test Bed No. 2. [linear aerospike test bed for thrust vector control  

NASA Technical Reports Server (NTRS)

Test bed No. 2 consists of 10 combustors welded in banks of 5 to 2 symmetrical tubular nozzle assemblies, an upper stationary thrust frame, a lower thrust frame which can be hinged, a power package, a triaxial combustion wave ignition system, a pneumatic control system, pneumatically actuated propellant valves, a purge and drain system, and an electrical control system. The power package consists of the Mark 29-F fuel turbopump, the Mark 29-0 oxidizer turbopump, a gas generator assembly, and propellant ducting. The system, designated as a linear aerospike system, was designed to demonstrate the feasibility of the concept and to explore technology related to thrust vector control, thrust vector optimization, improved sequencing and control, and advanced ignition systems. The propellants are liquid oxygen/liquid hydrogen. The system was designed to operate at 1200-psia chamber pressure at an engine mixture ratio of 5.5. With 10 combustors, the sea level thrust is 95,000 pounds.

1974-01-01

73

Implementation of the Orbital Maneuvering Systems Engine and Thrust Vector Control for the European Service Module  

NASA Technical Reports Server (NTRS)

The European Space Agency (ESA) has entered into a partnership with the National Aeronautics and Space Administration (NASA) to develop and provide the Service Module (SM) for the Orion Multipurpose Crew Vehicle (MPCV) Program. The European Service Module (ESM) will provide main engine thrust by utilizing the Space Shuttle Program Orbital Maneuvering System Engine (OMS-E). Thrust Vector Control (TVC) of the OMS-E will be provided by the Orbital Maneuvering System (OMS) TVC, also used during the Space Shuttle Program. NASA will be providing the OMS-E and OMS TVC to ESA as Government Furnished Equipment (GFE) to integrate into the ESM. This presentation will describe the OMS-E and OMS TVC and discuss the implementation of the hardware for the ESM.

Millard, Jon

2014-01-01

74

A static investigation of the thrust vectoring system of the F/A-18 high-alpha research vehicle  

NASA Technical Reports Server (NTRS)

A static (wind-off) test was conducted in the static test facility of the Langley 16-foot Transonic Tunnel to evaluate the vectoring capability and isolated nozzle performance of the proposed thrust vectoring system of the F/A-18 high alpha research vehicle (HARV). The thrust vectoring system consisted of three asymmetrically spaced vanes installed externally on a single test nozzle. Two nozzle configurations were tested: A maximum afterburner-power nozzle and a military-power nozzle. Vane size and vane actuation geometry were investigated, and an extensive matrix of vane deflection angles was tested. The nozzle pressure ratios ranged from two to six. The results indicate that the three vane system can successfully generate multiaxis (pitch and yaw) thrust vectoring. However, large resultant vector angles incurred large thrust losses. Resultant vector angles were always lower than the vane deflection angles. The maximum thrust vectoring angles achieved for the military-power nozzle were larger than the angles achieved for the maximum afterburner-power nozzle.

Mason, Mary L.; Capone, Francis J.; Asbury, Scott C.

1992-01-01

75

A simple dynamic engine model for use in a real-time aircraft simulation with thrust vectoring  

NASA Technical Reports Server (NTRS)

A simple dynamic engine model was developed for use in thrust vectoring control law development and real-time aircraft simulation. Engine dynamics were simulated using a throttle rate limiter and low-pass filter. This paper includes a description of a method to account for axial thrust loss resulting from thrust vectoring and the development of the simple dynamic engine model and its incorporation into the F-18 high alpha research vehicle (HARV) thrust vectoring simulation. The simple dynamic engine model was evaluated at Mach 0.2, 35,000-ft altitude and at Mach 0.7, 35,000-ft altitude. The simple dynamic engine model is within 3 percent of the steady state response, and within 25 percent of the transient response of the complete nonlinear dynamic engine model.

Johnson, Steven A.

1990-01-01

76

The digital autopilot for thrust vector control of the Shuttle Orbital maneuvering system  

NASA Technical Reports Server (NTRS)

This paper describes the requirements for and the design, development and performance of the digital autopilots (DAPs) for thrust vector control, utilizing the orbital maneuvering system (OMS) of the Space Shuttle Orbiter. The hardware and software requirements which caused the design to assume its current form are described. Also, the design synthesis, which considered rigid body stability margins, bending and slosh stabilization, guidance loop compensation, off-nominal performance and hardware and software limitations is presented. The performance of the OMS control system is summarized utilizing flight data from the first three Space Transportation System (STS) flights.

Penchuk, A.; Croopnick, S.

1982-01-01

77

Static internal performance of a two-dimensional convergent-divergent nozzle with thrust vectoring  

NASA Technical Reports Server (NTRS)

A parametric investigation of the static internal performance of multifunction two-dimensional convergent-divergent nozzles has been made in the static test facility of the Langley 16-Foot Transonic Tunnel. All nozzles had a constant throat area and aspect ratio. The effects of upper and lower flap angles, divergent flap length, throat approach angle, sidewall containment, and throat geometry were determined. All nozzles were tested at a thrust vector angle that varied from 5.60 tp 23.00 deg. The nozzle pressure ratio was varied up to 10 for all configurations.

Bare, E. Ann; Reubush, David E.

1987-01-01

78

Performance of twin two-dimensional wedge nozzles including thrust vectoring and reversing effects at speeds up to Mach 2.20  

NASA Technical Reports Server (NTRS)

Transonic tunnel and supersonic pressure tunnel tests were reformed to determine the performance characteristics of twin nonaxisymmetric or two-dimensional nozzles with fixed shrouds and variable-geometry wedges. The effects of thrust vectoring, reversing, and installation of various tails were also studied. The investigation was conducted statically and at flight speeds up to a Mach number of 2.20. The total pressure ratio of the simulated jet exhaust was varied up to approximately 26 depending on Mach number. The Reynolds number per meter varied up to 13.20 x 1 million. An analytical study was made to determine the effect on calculated wave drag by varying the mathematical model used to simulate nozzle jet-exhaust plume.

Capone, F. J.; Maiden, D. L.

1977-01-01

79

Design of a mixer for the thrust-vectoring system on the high-alpha research vehicle  

NASA Technical Reports Server (NTRS)

One of the advanced control concepts being investigated on the High-Alpha Research Vehicle (HARV) is multi-axis thrust vectoring using an experimental thrust-vectoring (TV) system consisting of three hydraulically actuated vanes per engine. A mixer is used to translate the pitch-, roll-, and yaw-TV commands into the appropriate TV-vane commands for distribution to the vane actuators. A computer-aided optimization process was developed to perform the inversion of the thrust-vectoring effectiveness data for use by the mixer in performing this command translation. Using this process a new mixer was designed for the HARV and evaluated in simulation and flight. An important element of the Mixer is the priority logic, which determines priority among the pitch-, roll-, and yaw-TV commands.

Pahle, Joseph W.; Bundick, W. Thomas; Yeager, Jessie C.; Beissner, Fred L., Jr.

1996-01-01

80

A numerical and experimental investigation of the thrust vector control by secondary gas injection  

NASA Astrophysics Data System (ADS)

A numerical and experimental analysis of the cross injection of secondary gas stream into a supersonic flow is presented. The two dimensional compressible Navier-Stokes equations were solved by the explicit Runge-Kutta finite volume method. The equations describing the turbulent flow are closed by an algebraic turbulence model. The results of the numerical calculations are compared with experimental results performed in a rectangular expansion nozzle with a two dimensional injector. Shadow graphs, wall pressure, and side thrust measurements were used as diagnostic tools. A parametric study concerning the influence of different injection conditions and gas media delivers the best injection conditions for a maximal side thust. The effect of the different jet injection conditions is discussed in connection with the corresponding flow structure.

Waidmann, Winfried

1991-07-01

81

An experimental study of blowdown thrust and jet forces for a pipe under boiling water reactor loss of coolant accident conditions  

Microsoft Academic Search

Blowdown thrust and jet impingement forces are simultaneously examined in jet discharge tests relating to an instantaneous pipe rupture accident. Tests were performed with a 6-in. pipe under boiling water reactor loss of coolant accident conditions. The initial pressure of the hot saturated water was 6.86 MPa. The time history of the blowdown thrust force just after the break, the

T. Yano; T. Isozaki; R. Kato; R. Kurihara; N. Miyazaki; S. Miyazono

1984-01-01

82

Low speed aerodynamic characteristics of a vectored thrust V/STOL transport with two lift/cruise fans  

NASA Technical Reports Server (NTRS)

A wind tunnel test was conducted to obtain power on low speed characteristics of a twin fan vectored thrust V/STOL transport aircraft. Longitudinal, as well as some lateral directional data, were analyzed. Hover, STOL, and conventional flight modes were investigated. Determination of STOL characteristics, hover characteristics, roll control effectiveness and aircraft attitude were evaluated. The study also included various means to improve the lifting capability of the aircraft such as by application of fuselage strakes, exhaust vanes capable of shifting the thrust vector aft, and external flap blowing for STOL performance.

Renselaer, D. J.

1977-01-01

83

Variable-flavor-number scheme for final state jets in thrust  

NASA Astrophysics Data System (ADS)

We present results for mass effects coming from secondary radiation of heavy quark pairs related to gluon splitting in the thrust distribution for e+e- collisions. The results are given in the dijet limit where the hard interaction scale and the scales related to collinear and soft radiation are widely separated. We account for the corresponding fixed-order corrections at O (?s2) and the summation of all logarithmic terms related to the hard, collinear, and soft scales as well as the quark mass at N3LL order. We also remove the O (?QCD) renormalon in the partonic soft function, leading to an infrared evolution equation with a matching condition related to the massive quark threshold. The quark mass can be arbitrary, ranging from the infinitely heavy case, where decoupling takes place, down to the massless limit, where the results smoothly merge into the well-known predictions for massless quarks. Our results are formulated in the framework of factorization theorems for e+e- dijet production and provide universal threshold corrections for the renormalization group evolution of the hard current, the jet, and the soft functions at the scale where the massive quarks are integrated out. The results represent a first explicit realization of a variable-flavor-number scheme for final-state jets along the lines of the well-known flavor-number-dependent evolution of the strong coupling ?s and the parton distribution functions.

Pietrulewicz, Piotr; Gritschacher, Simon; Hoang, Andre H.; Jemos, Ilaria; Mateu, Vicent

2014-12-01

84

Periodic Excitation for Jet Vectoring and Enhanced Spreading  

NASA Technical Reports Server (NTRS)

The effects of periodic excitation on the evolution of a turbulent jet were studied experimentally. A short, wide-angle diffuser was attached to the jet exit and excitation was introduced at the junction between the jet exit and the diffuser inlet. The introduction of high amplitude periodic excitation at the jet exit enhances the mixing and promotes attachment of the jet shear-layer to the diffuser wall. Vectoring is achieved by applying the excitation over a fraction of the circumference of the circular jet, enhancing its spreading rate on the excited side and its tendency to reattach to that side. Static deflection studies demonstrate that the presence of the wide-angle diffuser increases the effectiveness of the added periodic momentum due to a favorable interaction between the excitation, the jet shear-layer and the diffuser wall. This point was further demonstrated by the evolution of a wave packet that was excited in the jet shear-layer. Strong amplification of the wave packet was measured with a diffuser attached to the jet exit. The turbulent jet responds quickly (10-20 msec) to step changes in the level of the excitation input. The response scales with the jet exit velocity and is independent of the Reynolds number. Jet deflection angles were found to be highly sensitive to the relative direction between the excitation and the jet flow and less sensitive to the excitation frequency. The higher jet deflection angles were obtained for a diffuser length of about two diameters and for diffusers with half-angles greater than 15 degrees.

Pack, LaTunia G.; Seifert, Avi

1999-01-01

85

A simple dynamic engine model for use in a real-time aircraft simulation with thrust vectoring  

NASA Technical Reports Server (NTRS)

A simple dynamic engine model was developed at the NASA Ames Research Center, Dryden Flight Research Facility, for use in thrust vectoring control law development and real-time aircraft simulation. The simple dynamic engine model of the F404-GE-400 engine (General Electric, Lynn, Massachusetts) operates within the aircraft simulator. It was developed using tabular data generated from a complete nonlinear dynamic engine model supplied by the manufacturer. Engine dynamics were simulated using a throttle rate limiter and low-pass filter. Included is a description of a method to account for axial thrust loss resulting from thrust vectoring. In addition, the development of the simple dynamic engine model and its incorporation into the F-18 high alpha research vehicle (HARV) thrust vectoring simulation. The simple dynamic engine model was evaluated at Mach 0.2, 35,000 ft altitude and at Mach 0.7, 35,000 ft altitude. The simple dynamic engine model is within 3 percent of the steady state response, and within 25 percent of the transient response of the complete nonlinear dynamic engine model.

Johnson, Steven A.

1990-01-01

86

Independent Orbiter Assessment (IOA): Assessment of the ascent thrust vector control actuator subsystem FMEA/CIL  

NASA Technical Reports Server (NTRS)

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA effort first completed an analysis of the Ascent Thrust Vector Control Actuator (ATVD) hardware, generating draft failure modes and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The IOA results were then compared to the NASA FMEA/CIL baseline with proposed Post 51-L updates included. A resolution of each discrepancy from the comparison is provided through additional analysis as required. This report documents the results of that comparison for the Orbiter ATVC hardware. The IOA product for the ATVC actuator analysis consisted of 25 failure mode worksheets that resulted in 16 potential critical items being identified. Comparison was made to the NASA baseline which consisted of 21 FMEAs and 13 CIL items. This comparison produced agreement on all CIL items. Based on the Pre 51-L baseline, all non-CIL FMEAs were also in agreement.

Wilson, R. E.

1988-01-01

87

Preliminary Investigation on Battery Sizing Investigation for Thrust Vector Control on Ares I and Ares V Launch Vehicles  

NASA Technical Reports Server (NTRS)

An investigation into the merits of battery powered Electro Hydrostatic Actuation (EHA) for Thrust Vector Control (TVC) of the Ares I and Ares V launch vehicles is described. A top level trade study was conducted to ascertain the technical merits of lithium-ion (Li-ion) and thermal battery performance to determine the preferred choice of an energy storage system chemistry that provides high power discharge capability for a relatively short duration.

Miller, Thomas B.

2011-01-01

88

Thrust-vector control of a three-axis stabilized upper-stage rocket with fuel slosh dynamics  

NASA Astrophysics Data System (ADS)

This paper studies the thrust vector control problem for an upper-stage rocket with fuel slosh dynamics. The dynamics of a three-axis stabilized spacecraft with a single partially-filled fuel tank are formulated and the sloshing propellant is modeled as a multi-mass-spring system, where the oscillation frequencies of the mass-spring elements represent the prominent sloshing modes. The equations of motion are expressed in terms of the three-dimensional spacecraft translational velocity vector, the attitude, the angular velocity, and the internal coordinates representing the slosh modes. A Lyapunov-based nonlinear feedback control law is proposed to control the translational velocity vector and the attitude of the spacecraft, while attenuating the sloshing modes characterizing the internal dynamics. A simulation example is included to illustrate the effectiveness of the control law.

Rubio Hervas, Jaime; Reyhanoglu, Mahmut

2014-05-01

89

Thrust vectoring effects of a transverse gas injection into a supersonic cross flow of an axisymmetric convergent-divergent nozzle  

NASA Astrophysics Data System (ADS)

The transverse gas injection into the main supersonic flow of an axisymmetric convergent-divergent (C-D) propulsive nozzle is investigated for the fluidic thrust vectoring (FTV) possibilities as the segment part of the CNES "Perseus" project. Truncated ideal contour and conical C-D nozzles with different position and angle of the secondary circular injection port are selected as test models in the current numerical and experimental study. Analytical approach revealed parameters which affect the FTV efficiency, these criterions are further numerically explored and results data of the conical nozzle test cases are compared and coupled with the ones from experiments. It is found that upstream inclined injection has positive effect on vectoring capabilities and that with moderate secondary to primary mass-flow ratios, ranging around 5%, pertinent vector side force is possible to be achieved.

Zmijanovic, V.; Lago, V.; Leger, L.; Depussay, E.; Sellam, M.; Chpoun, A.

2013-03-01

90

Large-Scale Wind-Tunnel Tests of Exhaust Ingestion Due to Thrust Reversal on a Four-Engine Jet Transport during Ground Roll  

NASA Technical Reports Server (NTRS)

Wind-tunnel tests have been conducted on a large-scale model of a swept-wing jet transport type airplane to study the factors affecting exhaust gas ingestion into the engine inlets when thrust reversal is used during ground roll. The model was equipped with four small jet engines mounted in nacelles beneath the wing. The tests included studies of both cascade and target type reversers. The data obtained included the free-stream velocity at the occurrence of exhaust gas ingestion in the outboard engine and the increment of drag due to thrust reversal for various modifications of thrust reverser configuration. Motion picture films of smoke flow studies were also obtained to supplement the data. The results show that the free-stream velocity at which ingestion occurred in the outboard engines could be reduced considerably, by simple modifications to the reversers, without reducing the effective drag due to reversed thrust.

Tolhurst, William H., Jr.; Hickey, David H.; Aoyagi, Kiyoshi

1961-01-01

91

Static internal performance of a thrust vectoring and reversing two-dimensional convergent-divergent nozzle with an aft flap  

NASA Technical Reports Server (NTRS)

The static internal performance of a multifunction nozzle having some of the geometric characteristics of both two-dimensional convergent-divergent and single expansion ramp nozzles has been investigated in the static-test facility of the Langley 16-Foot Transonic Tunnel. The internal expansion portion of the nozzle consisted of two symmetrical flat surfaces of equal length, and the external expansion portion of the nozzle consisted of a single aft flap. The aft flap could be varied in angle independently of the upper internal expansion surface to which it was attached. The effects of internal expansion ratio, nozzle thrust-vector angle (-30 deg. to 30 deg., aft flap shape, aft flap angle, and sidewall containment were determined for dry and afterburning power settings. In addition, a partial afterburning power setting nozzle, a fully deployed thrust reverser, and four vertical takeoff or landing nozzle, configurations were investigated. Nozzle pressure ratio was varied up to 10 for the dry power nozzles and 7 for the afterburning power nozzles.

Re, R. J.; Leavitt, L. D.

1986-01-01

92

Optimal dimensionless design and analysis of jet ejectors as compressors and thrust augmenters  

E-print Network

together for this project. Thanks to Manoranjan Majji for being an understanding teammate in our times together for ?The Morphing Wing? project. vii TABLE OF CONTENTS.......................................................................................................................10 JET EJECTOR AS PROPELLERS..................................................................................11 General .........................................................................................................................11...

Mohan, Ganesh

2006-08-16

93

Engine inlet distortion in a 9.2 percent scaled vectored thrust STOVL model in ground effect  

NASA Technical Reports Server (NTRS)

Advanced Short Takeoff/Vertical Landing (STOVL) aircraft which can operate from remote locations, damaged runways, and small air capable ships are being pursued for deployment around the turn of the century. To achieve this goal, a cooperative program has been defined for testing in the NASA Lewis 9- by 15-foot Low Speed Wind Tunnel (LSWT) to establish a database for hot gas ingestion, one of the technologies critical to STOVL. This paper presents results showing the engine inlet distortions (both temperature and pressure) in a 9.2 percent scale Vectored Thrust STOVL model in ground effects. Results are shown for the forward nozzle splay angles of 0, -6, and 18 deg. The model support system had 4 deg of freedom, heated high pressure air for nozzle flow, and a suction system exhaust for inlet flow. The headwind (freestream) velocity was varied from 8 to 23 kn.

Johns, Albert L.; Neiner, George; Flood, J. D.; Amuedo, K. C.; Strock, T. W.

1989-01-01

94

Noise generated by a flight weight, air flow control valve in a vertical takeoff and landing aircraft thrust vectoring system  

NASA Astrophysics Data System (ADS)

Tests were conducted in the NASA Lewis Research Center's Powered Lift Facility to experimentally evaluate the noise generated by a flight weight, 12 in. butterfly valve installed in a proposed vertical takeoff and landing thrust vectoring system. Fluctuating pressure measurements were made in the circular duct upstream and downstream of the valve. This data report presents the results of these tests. The maximum overall sound pressure level is generated in the duct downstream of the valve and reached a value of 180 dB at a valve pressure ratio of 2.8. At the higher valve pressure ratios the spectra downstream of the valve is broad banded with its maximum at 1000 Hz.

Huff, Ronald G.

1989-02-01

95

Noise generated by a flight weight, air flow control valve in a vertical takeoff and landing aircraft thrust vectoring system  

NASA Technical Reports Server (NTRS)

Tests were conducted in the NASA Lewis Research Center's Powered Lift Facility to experimentally evaluate the noise generated by a flight weight, 12 in. butterfly valve installed in a proposed vertical takeoff and landing thrust vectoring system. Fluctuating pressure measurements were made in the circular duct upstream and downstream of the valve. This data report presents the results of these tests. The maximum overall sound pressure level is generated in the duct downstream of the valve and reached a value of 180 dB at a valve pressure ratio of 2.8. At the higher valve pressure ratios the spectra downstream of the valve is broad banded with its maximum at 1000 Hz.

Huff, Ronald G.

1989-01-01

96

Flight-Determined Subsonic Longitudinal Stability and Control Derivatives of the F-18 High Angle of Attack Research Vehicle (HARV) with Thrust Vectoring  

NASA Technical Reports Server (NTRS)

The subsonic longitudinal stability and control derivatives of the F-18 High Angle of Attack Research Vehicle (HARV) are extracted from dynamic flight data using a maximum likelihood parameter identification technique. The technique uses the linearized aircraft equations of motion in their continuous/discrete form and accounts for state and measurement noise as well as thrust-vectoring effects. State noise is used to model the uncommanded forcing function caused by unsteady aerodynamics over the aircraft, particularly at high angles of attack. Thrust vectoring was implemented using electrohydraulically-actuated nozzle postexit vanes and a specialized research flight control system. During maneuvers, a control system feature provided independent aerodynamic control surface inputs and independent thrust-vectoring vane inputs, thereby eliminating correlations between the aircraft states and controls. Substantial variations in control excitation and dynamic response were exhibited for maneuvers conducted at different angles of attack. Opposing vane interactions caused most thrust-vectoring inputs to experience some exhaust plume interference and thus reduced effectiveness. The estimated stability and control derivatives are plotted, and a discussion relates them to predicted values and maneuver quality.

Iliff, Kenneth W.; Wang, Kon-Sheng Charles

1997-01-01

97

Advanced solid rocket motor nozzle thrust vector control flexseal development status  

NASA Astrophysics Data System (ADS)

The advanced solid rocket motor (ASRM) flexseal development status is reviewed focusing on design goals and requirements, design configuration, analysis activities, and verification tests. It is concluded that the ASRM flexseal incorporates flight-proven materials in an innovative design configuration. Variable thickness shims and efficient packaging of the flexseal make it possible to achieve a significant weight reduction. A flexseal insulator design derived from strategic solid rocket motor experience will provide the necessary bearing thermal protection while minimizing vectoring torque variability.

Prins, William S.; Meyer, Scott A.; Cox, Paul D.

1992-07-01

98

A Method for Integrating Thrust-Vectoring and Actuated Forebody Strakes with Conventional Aerodynamic Controls on a High-Performance Fighter Airplane  

NASA Technical Reports Server (NTRS)

A method, called pseudo controls, of integrating several airplane controls to achieve cooperative operation is presented. The method eliminates conflicting control motions, minimizes the number of feedback control gains, and reduces the complication of feedback gain schedules. The method is applied to the lateral/directional controls of a modified high-performance airplane. The airplane has a conventional set of aerodynamic controls, an experimental set of thrust-vectoring controls, and an experimental set of actuated forebody strakes. The experimental controls give the airplane additional control power for enhanced stability and maneuvering capabilities while flying over an expanded envelope, especially at high angles of attack. The flight controls are scheduled to generate independent body-axis control moments. These control moments are coordinated to produce stability-axis angular accelerations. Inertial coupling moments are compensated. Thrust-vectoring controls are engaged according to their effectiveness relative to that of the aerodynamic controls. Vane-relief logic removes steady and slowly varying commands from the thrust-vectoring controls to alleviate heating of the thrust turning devices. The actuated forebody strakes are engaged at high angles of attack. This report presents the forward-loop elements of a flight control system that positions the flight controls according to the desired stability-axis accelerations. This report does not include the generation of the required angular acceleration commands by means of pilot controls or the feedback of sensed airplane motions.

Lallman, Frederick J.; Davidson, John B.; Murphy, Patrick C.

1998-01-01

99

Static thrust-vectoring performance of nonaxisymmetric convergent-divergent nozzles with post-exit yaw vanes. M.S. Thesis - George Washington Univ., Aug. 1988  

NASA Technical Reports Server (NTRS)

A static (wind-off) test was conducted in the Static Test Facility of the 16-ft transonic tunnel to determine the performance and turning effectiveness of post-exit yaw vanes installed on two-dimensional convergent-divergent nozzles. One nozzle design that was previously tested was used as a baseline, simulating dry power and afterburning power nozzles at both 0 and 20 degree pitch vectoring conditions. Vanes were installed on these four nozzle configurations to study the effects of vane deflection angle, longitudinal and lateral location, size, and camber. All vanes were hinged at the nozzle sidewall exit, and in addition, some were also hinged at the vane quarter chord (double-hinged). The vane concepts tested generally produced yaw thrust vectoring angles much less than the geometric vane angles, for (up to 8 percent) resultant thrust losses. When the nozzles were pitch vectored, yawing effectiveness decreased as the vanes were moved downstream. Thrust penalties and yawing effectiveness both decreased rapidly as the vanes were moved outboard (laterally). Vane length and height changes increased yawing effectiveness and thrust ratio losses, while using vane camber, and double-hinged vanes increased resultant yaw angles by 50 to 100 percent.

Foley, Robert J.; Pendergraft, Odis C., Jr.

1991-01-01

100

Closed-Loop Simulation Study of the Ares I Upper Stage Thrust Vector Control Subsystem for Nominal and Failure Scenarios  

NASA Technical Reports Server (NTRS)

As a replacement to the current Shuttle, the Ares I rocket and Orion crew module are currently under development by the National Aeronautics and Space Administration (NASA). This new launch vehicle is segmented into major elements, one of which is the Upper Stage (US). The US is further broken down into subsystems, one of which is the Thrust Vector Control (TVC) subsystem which gimbals the US rocket nozzle. Nominal and off-nominal simulations for the US TVC subsystem are needed in order to support the development of software used for control systems and diagnostics. In addition, a clear and complete understanding of the effect of off-nominal conditions on the vehicle flight dynamics is desired. To achieve these goals, a simulation of the US TVC subsystem combined with the Ares I vehicle as developed. This closed-loop dynamic model was created using Matlab s Simulink and a modified version of a vehicle simulation, MAVERIC, which is currently used in the Ares I project and was developed by the Marshall Space Flight Center (MSFC). For this report, the effects on the flight trajectory of the Ares I vehicle are investigated after failures are injected into the US TVC subsystem. The comparisons of the off-nominal conditions observed in the US TVC subsystem with those of the Ares I vehicle flight dynamics are of particular interest.

Chicatelli, Amy; Fulton, Chris; Connolly, Joe; Hunker, Keith

2010-01-01

101

Application of the scalar and vector potentials to the aerodynamics of jets  

NASA Technical Reports Server (NTRS)

The applicability of a method based on the Stokes potentials (vector and scalar potentials) to computations associated with the aerodynamics of jets was examined. The aerodynamic field near the nozzle could be represented and that the influence of a nonuniform velocity profile at the nozzle exit plane could be determined. Also computations were made for an axisymmetric jet exhausting into a quiescient atmosphere. The velocity at the axis of the jet, and the location of the half-velocity points along the jet yield accurate aerodynamic field computations. Inconsistencies among the different theoretical characterizations of jet flowfields are shown.

Russell, H. L.; Skifstad, J. G.

1973-01-01

102

Thrust and drag characteristics of a convergent-divergent nozzle with various exhaust jet temperatures  

NASA Technical Reports Server (NTRS)

An investigation was conducted in the 8-by-6 foot supersonic wind tunnel on the effect of exhaust-gas temperatures on the external and internal characteristics of a convergent-divergent nozzle having an area expansion ratio of 1.83. Data were obtained over a pressure-ratio range from 1 to 20 at free-stream Mach numbers of 1.6 and 2.0 for exhaust temperatures of 860 degrees, 1650 degrees, and 2000 degrees R. Results of this investigation indicated that generally both the internal and external performance characteristics were only slightly affected by a large change in jet temperature. The small differences in performance which did occur were predicted satisfactorily from theoretical considerations.

Hearth, Donald P; Wilcox, Fred A

1954-01-01

103

Using jet mass to discover vector quarks at the CERN LHC  

Microsoft Academic Search

We illustrate the utility of jet-mass distributions as probes of new physics at the LHC, focusing on a heavy vector-quark doublet that mixes with the top as a concrete example. For 1 TeV vector-quark masses, we find that signals with greater than 5sigma significance can be achieved after 100fb-1. More generally, jet-mass distributions have the potential to provide signals for

Witold Skiba; David Tucker-Smith

2007-01-01

104

Design Specification for a Thrust-Vectoring, Actuated-Nose-Strake Flight Control Law for the High-Alpha Research Vehicle  

NASA Technical Reports Server (NTRS)

Specifications for a flight control law are delineated in sufficient detail to support coding the control law in flight software. This control law was designed for implementation and flight test on the High-Alpha Research Vehicle (HARV), which is an F/A-18 aircraft modified to include an experimental multi-axis thrust-vectoring system and actuated nose strakes for enhanced rolling (ANSER). The control law, known as the HARV ANSER Control Law, was designed to utilize a blend of conventional aerodynamic control effectors, thrust vectoring, and actuated nose strakes to provide increased agility and good handling qualities throughout the HARV flight envelope, including angles of attack up to 70 degrees.

Bacon, Barton J.; Carzoo, Susan W.; Davidson, John B.; Hoffler, Keith D.; Lallman, Frederick J.; Messina, Michael D.; Murphy, Patrick C.; Ostroff, Aaron J.; Proffitt, Melissa S.; Yeager, Jessie C.; Foster, John V.; Bundick, W. Thomas; Connelly, Patrick J.; Kelly, John W.; Pahle, Joseph W.; Thomas, Michael; Wichman, Keith D.; Wilson, R. Joseph

1996-01-01

105

Thrust and mass flow characteristics of four 36 inch diameter tip turbine fan thrust vectoring systems in and out of ground effect  

NASA Technical Reports Server (NTRS)

The calibration tests carried out on the propulsion system components of a 70 percent scale, powered model of a NASA 3-fan V/STOL aircraft configuration are described. The three X3/6B/T58 turbotip fan units used in the large scale powered model were tested on an isolated basis over a range of ground heights from H/D of 1.02 to infinity. A higher pressure ratio LF336/J85 fan unit was tested over a range of ground heights from 1.55 to infinity. The results of the test program demonstrated that: (1) the thrust and mass flow performance of the X376B/T58 nose lift unit is essentially constant for H/D variations down to 1.55; at H/D 1.02 back pressurization of the fan exit occurs and is accompanied by an increase in thrust of five percent; (2) a change in nose fan exit hub shape from flat plate to hemispherical produces no significant difference in louvered lift nozzle performance for height variations from H/D = 1.02 to infinity; (3) operation of the nose lift nozzle at the higher fan pressure ratio generated by the LF336/J85 fan system causes no significant change in ground proximity performance down to an H/D of 1.55, the lowest height tested with this unit; and (4) the performance of the left and right X376B/T58 lift/cruise units in the vertical lift mode remains unchanged, within plus or minus two percent for the range of ground heights from H/D = 1.02 to infinity.

Esker, D. W.; Roddiger, H. A.

1979-01-01

106

Flight Measurements of the Effect of a Controllable Thrust Reverser on the Flight Characteristics of a Single-Engine Jet Airplane  

NASA Technical Reports Server (NTRS)

A flight investigation was undertaken to determine the effect of a fully controllable thrust reverser on the flight characteristics of a single-engine jet airplane. Tests were made using a cylindrical target-type reverser actuated by a hydraulic cylinder through a "beep-type" cockpit control mounted at the base of the throttle. The thrust reverser was evaluated as an in-flight decelerating device, as a flight path control and airspeed control in landing approach, and as a braking device during the ground roll. Full deflection of the reverser for one reverser configuration resulted in a reverse thrust ratio of as much as 85 percent, which at maximum engine power corresponded to a reversed thrust of 5100 pounds. Use of the reverser in landing approach made possible a wide selection of approach angles, a large reduction in approach speed at steep approach angles, improved control of flight path angle, and more accuracy in hitting a given touchdown point. The use of the reverser as a speed brake at lower airspeeds was compromised by a longitudinal trim change. At the lower airspeeds and higher engine powers there was insufficient elevator power to overcome the nose-down trim change at full reverser deflection.

Anderson, Seth B.; Cooper, George E.; Faye, Alan E., Jr.

1959-01-01

107

Vector Boson Jets with BlackHat and Sherpa  

SciTech Connect

We review recent NLO QCD results for W, Z + 3-jet production at hadron colliders, computing using BlackHat and SHERPA, and including also some new results for Z + 3-jet production for the LHC at 7 TeV. We report new progress towards the NLO cross section for W + 4-jet production. In particular, we show that the virtual matrix elements produced by BlackHat are numerically stable. We also show that with an improved integrator and tree-level matrix elements from BlackHat, SHERPA produces well-behaved real-emission contributions. As an illustration, we present the real-emission contributions - including dipole-subtraction terms - to the p{sub T} distribution of the fourth jet, for a single subprocess with the maximum number of gluons.

Berger, C.F.; /MIT, LNS; Bern, Z.; /UCLA; Dixon, Lance J.; /SLAC; Cordero, F.Febres; /Simon Bolivar U.; Forde, D.; /CERN /NIKHEF, Amsterdam; Gleisberg, T.; /SLAC; Ita, H.; /UCLA; Kosower, D.A.; /Saclay, SPhT; Maitre, D.; /Durham U.

2010-08-25

108

Vector boson + multi jets at NLO Harald Ita, UCLA  

E-print Network

level hard scattering · parton model · perturbative QCD · jet algorithms Proton Proton PT(hard) Outgoing Parton Outgoing Parton Underlying EventUnderlying Event Initial-State Radiation Final-State Radiation #12

California at Santa Cruz, University of

109

Using jet mass to discover vector quarks at the CERN LHC  

SciTech Connect

We illustrate the utility of jet-mass distributions as probes of new physics at the LHC, focusing on a heavy vector-quark doublet that mixes with the top as a concrete example. For 1 TeV vector-quark masses, we find that signals with greater than 5{sigma} significance can be achieved after 100 fb{sup -1}. More generally, jet-mass distributions have the potential to provide signals for heavy states that produce highly boosted weak gauge bosons and/or top quarks.

Skiba, Witold [Department of Physics, Yale University, New Haven, Connecticut 06520 (United States); Tucker-Smith, David [Department of Physics, Williams College, Williamstown, Massachusetts 01267 (United States)

2007-06-01

110

Design of supersonic Coanda jet nozzles  

NASA Technical Reports Server (NTRS)

The thrust vectoring of supersonic Coanda jets was improved by designing a nozzle to skew the initial jet velocity profile. A new nozzle design procedure, based on the method of characteristics, was developed to design a nozzle which produces a specified exit velocity profile. The thrust vectoring of a simple convergent nozzle, a convergent-divergent nozzle, and a nozzle which produces a skewed velocity profile matched to the curvature of the Coanda surface were expermentially compared over a range of pressure ratios from 1.5 to 3.5. Elimination of the expansion shocks with the C-D nozzle is shown to greatly improve the thrust vectoring; elimination of turning shocks with the skewed profile nozzle further improves the vectoring.

Bevilaqua, Paul M.; Lee, John D.

1987-01-01

111

Resummation Prediction on Higgs and Vector Boson Associated Production with a Jet Veto at the LHC  

E-print Network

We investigate the resummation effects for the SM Higgs and vector boson associated production at the LHC with a jet veto in soft-collinear effective theory using "collinear anomalous" formalism. We calculate the jet vetoed invariant mass distribution and the cross section for this process at Next-to-Next-to-Leading-Logarithmic level, which are matched to the QCD Next-to-Leading Order results, and compare the differences of the resummation effects with different jet veto $p_{T}^{\\rm veto}$ and jet radius $R$. Our results show that both resummation enhancement effects and the scale uncertainties decrease with the increasing of jet veto $p_{T}^{\\rm veto}$ and jet radius $R$, respectively. When $p_{T}^{\\rm veto}=25$ GeV and $R=0.4~(0.5)$, the resummation effects reduce the scale uncertainties of the Next-to-Leading Order jet vetoed cross sections to about $7\\%~(6\\%)$, which lead to increased confidence on the theoretical predictions. Besides, after including resummation effects, the PDF uncertainties of jet vetoed cross section are about $7\\%$.

Ding Yu Shao; Chong Sheng Li; Hai Tao Li

2014-03-02

112

Vectoring: Steering a Plane  

NSDL National Science Digital Library

In this two part activity, learners work in pairs or individually to discover how vectoring the thrust from a jet engine affects movement of an airplane. In part one, learners construct an F-15 ACTIVE model with a balloon engine. In part two, learners conduct a series of experiments by changing the angle of the straw to control the direction of the thrust. This activity emphasizes the scientific method including prediction, observation, data collection, and analysis. This lesson plan includes background information, an extension and a sample worksheet.

Nasa

2011-08-20

113

Search for vector-like quark production in the lepton+jets and dilepton+jets final states using 5.4 fb-1 of Run II data  

SciTech Connect

The Standard Model of particle physics provides an excellent description of particle interactions at energies up to {approx}1 TeV, but it is expected to fail above that scale. Multiple models developed to describe phenomena above the TeV scale predict the existence of very massive, vector-like quarks. A search for single electroweak production of such particles in p{anti p} collisions at a center-of-mass energy of 1.96 TeV is performed in the W+jets and Z+jets channels. The data were collected by the D0 detector at the Fermilab Tevatron Collider and correspond to an integrated luminosity of 5.4 fb{sup -1}. Events consistent with a heavy object decaying to a vector boson and a jet are selected. We observe no significant excess in comparison to the background prediction and set 95% confidence level upper limits on production cross sections for vector-like quarks decaying to W+jet and Z+jet. Assuming a vector-like quark -- standard model quark coupling parameter {tilde {kappa}}{sub qQ} of unity, we exclude vector-like quarks with mass below 693 GeV for decays to W+jet and mass below 449 GeV for decays to Z+jet. These represent the most sensitive limits to date.

Caughron, Seth; /Columbia U.

2010-10-01

114

Evaluation of dual flow thrust vectored nozzles with exhaust stream impingement. MS Thesis Final Technical Report, Oct. 1990 - Jul. 1991  

NASA Technical Reports Server (NTRS)

The main objective of this project was to predict the expansion wave/oblique shock wave structure in an under-expanded jet expanding from a convergent nozzle. The shock structure was predicted by combining the calculated curvature of the free pressure boundary with principles and governing equations relating to oblique shock wave and expansion wave interaction. The procedure was then continued until the shock pattern repeated itself. A mathematical model was then formulated and written in FORTRAN to calculate the oblique shock/expansion wave structure within the jet. In order to study shock waves in expanding jets, Schlieren photography, a form of flow visualization, was employed. Thirty-six Schlieren photographs of jets from both a straight and 15 degree nozzle were taken. An iterative procedure was developed to calculate the shock structure within the jet and predict the non-dimensional values of Prandtl primary wavelength (w/rn), distance to Mach Disc (Ld) and Mach Disc radius (rd). These values were then compared to measurements taken from Schlieren photographs and experimental results. The results agreed closely to measurements from Schlieren photographs and previously obtained data. This method provides excellent results for pressure ratios below that at which a Mach Disc first forms. Calculated values of non-dimensional distance to the Mach Disc (Ld) agreed closely to values measured from Schlieren photographs and published data. The calculated values of non-dimensional Mach Disc radius (rd), however, deviated from published data by as much as 25 percent at certain pressure ratios.

Carpenter, Thomas W.

1991-01-01

115

Performance characteristics of a variable-area vane nozzle for vectoring an ASTOVL exhaust jet up to 45 deg  

NASA Technical Reports Server (NTRS)

Many conceptual designs for advanced short-takeoff, vertical landing (ASTOVL) aircraft need exhaust nozzles that can vector the jet to provide forces and moments for controlling the aircraft's movement or attitude in flight near the ground. A type of nozzle that can both vector the jet and vary the jet flow area is called a vane nozzle. Basically, the nozzle consists of parallel, spaced-apart flow passages formed by pairs of vanes (vanesets) that can be rotated on axes perpendicular to the flow. Two important features of this type of nozzle are the abilities to vector the jet rearward up to 45 degrees and to produce less harsh pressure and velocity footprints during vertical landing than does an equivalent single jet. A one-third-scale model of a generic vane nozzle was tested with unheated air at the NASA Lewis Research Center's Powered Lift Facility. The model had three parallel flow passages. Each passage was formed by a vaneset consisting of a long and a short vane. The longer vanes controlled the jet vector angle, and the shorter controlled the flow area. Nozzle performance for three nominal flow areas (basic and plus or minus 21 percent of basic area), each at nominal jet vector angles from -20 deg (forward of vertical) to +45 deg (rearward of vertical) are presented. The tests were made with the nozzle mounted on a model tailpipe with a blind flange on the end to simulate a closed cruise nozzle, at tailpipe-to-ambient pressure ratios from 1.8 to 4.0. Also included are jet wake data, single-vaneset vector performance for long/short and equal-length vane designs, and pumping capability. The pumping capability arises from the subambient pressure developed in the cavities between the vanesets, which could be used to aspirate flow from a source such as the engine compartment. Some of the performance characteristics are compared with characteristics of a single-jet nozzle previously reported.

Mcardle, Jack G.; Esker, Barbara S.

1993-01-01

116

Thrust bearing  

NASA Technical Reports Server (NTRS)

A gas lubricated thrust bearing is described which employs relatively rigid inwardly cantilevered spokes carrying a relatively resilient annular member or annulus. This annulus acts as a beam on which are mounted bearing pads. The resilience of the beam mount causes the pads to accept the load and, with proper design, responds to a rotating thrust-transmitting collar by creating a gas film between the pads and the thrust collar. The bearing may be arranged for load equalization thereby avoiding the necessity of gimbal mounts or the like for the bearing. It may also be arranged to respond to rotation in one or both directions.

Anderson, W. J. (inventor)

1976-01-01

117

Support vector machine-based feature extractor for L/H transitions in JET  

SciTech Connect

Support vector machines (SVM) are machine learning tools originally developed in the field of artificial intelligence to perform both classification and regression. In this paper, we show how SVM can be used to determine the most relevant quantities to characterize the confinement transition from low to high confinement regimes in tokamak plasmas. A set of 27 signals is used as starting point. The signals are discarded one by one until an optimal number of relevant waveforms is reached, which is the best tradeoff between keeping a limited number of quantities and not loosing essential information. The method has been applied to a database of 749 JET discharges and an additional database of 150 JET discharges has been used to test the results obtained.

Gonzalez, S.; Vega, J.; Pereira, A. [Asociacion EURATOM/CIEMAT para Fusion, Madrid 28040 (Spain); Murari, A. [Consorzio RFX, Associazione EURATOM ENEA per la Fusione, Padova 4-35127 (Italy); Ramirez, J. M.; Dormido-Canto, S. [Departamento de Informatica y Automatica, UNED, Madrid 28040 (Spain); Collaboration: JET-EFDA Contributors

2010-10-15

118

The scaling of model test results to predict intake hot gas reingestion for STOVL aircraft with augmented vectored thrust engines  

NASA Technical Reports Server (NTRS)

The difficulties of modeling the complex recirculating flow fields produced by multiple jet STOVL aircraft close to the ground have led to extensive use of experimental model tests to predict intake Hot Gas Reingestion (HGR). Model test results reliability is dependent on a satisfactory set of scaling rules which must be validated by fully comparable full scale tests. Scaling rules devised in the U.K. in the mid 60's gave good model/full scale agreement for the BAe P1127 aircraft. Until recently no opportunity has occurred to check the applicability of the rules to the high energy exhaust of current ASTOVL aircraft projects. Such an opportunity has arisen following tests on a Tethered Harrier. Comparison of this full scale data and results from tests on a model configuration approximating to the full scale aircraft geometry has shown discrepancies between HGR levels. These discrepancies although probably due to geometry and other model/scale differences indicate some reexamination of the scaling rules is needed. Therefore the scaling rules are reviewed, further scaling studies planned are described and potential areas for further work are suggested.

Penrose, C. J.

1987-01-01

119

A static investigation of yaw vectoring concepts on two-dimensional convergent-divergent nozzles  

NASA Technical Reports Server (NTRS)

The flow-turning capability and nozzle internal performance of yaw-vectoring nozzle geometries were tested in the NASA Langley 16-ft Transonic wind tunnel. The concept was investigated as a means of enhancing fighter jet performance. Five two-dimensional convergent-divergent nozzles were equipped for yaw-vectoring and examined. The configurations included a translating left sidewall, left and right sidewall flaps downstream of the nozzle throat, left sidewall flaps or port located upstream of the nozzle throat, and a powered rudder. Trials were also run with 20 deg of pitch thrust vectoring added. The feasibility of providing yaw-thrust vectoring was demonstrated, with the largest yaw vector angles being obtained with sidewall flaps downstream of the nozzle primary throat. It was concluded that yaw vector designs that scoop or capture internal nozzle flow provide the largest yaw-vector capability, but decrease the thrust the most.

Berrier, B. L.; Mason, M. L.

1983-01-01

120

Vectors  

NSDL National Science Digital Library

This lesson was created by Larry Friesen and Anne Gillis for Butler Community College. It will help physics and calculus students differentiate between the uses of vectors in mathematics vs. physics. This website provides two PDF documents that give detailed lessons about vectors, including an overview of terminology, sample problems, and an HTML worksheet is also provided. For educators or students, this site offers well laid-out lessons and/or practice with vectors.

Friesen, Larry; Gillis, Anne

2008-04-18

121

vectors  

NSDL National Science Digital Library

The word vector comes from the Latin term vehere, to carry. In Biology, a vector is an agent which carries disease, such as a mosquito carrying infected blood from one patient to the next. In physics, a vector is a quantity which has both a magnitude and a direction associated with it. The most commonly used example of vectors in everyday life is velocity. When you drive your car, your speedometer tells you the speed of your car, but it doesn't tell you where you are going. The combination of both where you are going and how fast you are going there is your car's velocity.

David Joiner

122

Support Vector Machine Classification on a Biased Training Set: Multi-Jet Background Rejection at Hadron Colliders  

E-print Network

This paper describes an innovative way to optimize a multivariate classifier, in particular a Support Vector Machine algorithm, on a problem characterized by a biased training sample. This is possible thanks to the feedback of a signal-background template fit performed on a validation sample and included both in the optimization process and in the input variable selection. The procedure is applied to a real case of interest at hadron collider experiments: the reduction and the estimate of the multi-jet background in the $W\\to e \

Federico Sforza; Vittorio Lippi

2014-07-01

123

Vectors  

NSDL National Science Digital Library

This web page introduces vectors as an extension of numbers having both magnitude and direction. The initial motivation is to describe velocity but the material includes a general discussion of vector algebra and an application to forces for the inclined plane. The page contains links to a related lesson plan and further opportunities to explore vectors. This is part of the extensive web site "From Stargazers to Starships", that uses space exploration and space science to introduce topics in physics and astronomy. Translations in Spanish and French are available.

Stern, David

2006-07-16

124

Deciphering cumulative fault slip vectors from fold scarps: relationships between long-term and co-seismic deformation at the piedmont of the Taiwan fold-and-thrust belt  

NASA Astrophysics Data System (ADS)

We document the 30-ka cumulative slip history and long-term slip vector azimuth on the Northern Chelungpu fault based on a series of fault-bend folded alluvial terraces and draw quantitative relationships between geological structure, deformation observed from the geomorphology, and coseismic displacements during the 1999 Mw=7.6 Chi-Chi earthquake. In our study area, three main terrace levels show progressive folding by kink-band migration in relation to the underlying fault geometry, forming a main N-S fold scarp up to ~193 m high and secondary E-W scarps. Detailed analysis using 5-m resolution DEM allows us to characterize the scarp morphology and quantify the deformation parameters, namely terrace heights, fold scarp relief, and fold limb width and slope angle. The 3D deformation of the highest terrace, OSL-dated at 30.2 ± 4.0 ka, enables to simultaneously determine amplitude and azimuth of the long-term slip vector based on scarp relief. The long-term slip vector, oriented N338° ± 6°, is found to parallel the Chi-Chi coseismic displacements in this area. Cumulative slip and dating results yield a constant slip rate of 17.7 ± 2.2 mm/a in the direction N338° ± 6°, which represents ~16% of total shortening across the mountain belt. Late Quaternary shortening rates observed at four sites vary along-strike in similar proportion to Chi-Chi coseismic displacements. Together with the colinearity of long-term and coseismic slip vectors at our study site, this suggests that Chi-Chi earthquake is a characteristic earthquake for the Chelungpu thrust with recurrence interval ~440 years. We also discuss implications for the regional and long-term distribution of shortening in the central Western Foothills.

Le Beon, Maryline; Suppe, John; Jaiswal, Manoj; Chen, Yue-Gau; Ustaszewski, Michaela

2014-05-01

125

Design of high temperature high speed electromagnetic axial thrust bearing  

E-print Network

The National Aeronautics and Space Administration (NASA) is researching the magnetic bearings to use it as a better alternative to conventional bearings. This research was to develop an axial thrust electromagnetic bearing for high performance jet...

Mohiuddin, Mohammad Waqar

2012-06-07

126

Jet shapes with the broadening axis  

E-print Network

Broadening is a classic jet observable that probes the transverse momentum structure of jets. Traditionally, broadening has been measured with respect to the thrust axis, which is aligned along the (hemisphere) jet momentum ...

Larkoski, Andrew James

127

Flight-Determined, Subsonic, Lateral-Directional Stability and Control Derivatives of the Thrust-Vectoring F-18 High Angle of Attack Research Vehicle (HARV), and Comparisons to the Basic F-18 and Predicted Derivatives  

NASA Technical Reports Server (NTRS)

The subsonic, lateral-directional, stability and control derivatives of the thrust-vectoring F-1 8 High Angle of Attack Research Vehicle (HARV) are extracted from flight data using a maximum likelihood parameter identification technique. State noise is accounted for in the identification formulation and is used to model the uncommanded forcing functions caused by unsteady aerodynamics. Preprogrammed maneuvers provided independent control surface inputs, eliminating problems of identifiability related to correlations between the aircraft controls and states. The HARV derivatives are plotted as functions of angles of attack between 10deg and 70deg and compared to flight estimates from the basic F-18 aircraft and to predictions from ground and wind tunnel tests. Unlike maneuvers of the basic F-18 aircraft, the HARV maneuvers were very precise and repeatable, resulting in tightly clustered estimates with small uncertainty levels. Significant differences were found between flight and prediction; however, some of these differences may be attributed to differences in the range of sideslip or input amplitude over which a given derivative was evaluated, and to differences between the HARV external configuration and that of the basic F-18 aircraft, upon which most of the prediction was based. Some HARV derivative fairings have been adjusted using basic F-18 derivatives (with low uncertainties) to help account for differences in variable ranges and the lack of HARV maneuvers at certain angles of attack.

Iliff, Kenneth W.; Wang, Kon-Sheng Charles

1999-01-01

128

Variable thrust cartridge  

DOEpatents

The present invention is a variable thrust cartridge comprising a water-molten aluminum reaction chamber from which a slug is propelled. The cartridge comprises a firing system that initiates a controlled explosion from the reaction chamber. The explosive force provides a thrust to a slug, preferably contained within the cartridge.

Taleyarkhan, Rusi P. (Knoxville, TN)

2000-11-07

129

PPT Thrust Stand  

NASA Technical Reports Server (NTRS)

A torsional-type thrust stand has been designed and built to test Pulsed Plasma Thrusters (PPT's) in both single shot and repetitive operating modes. Using this stand, momentum per pulse was determined strictly as a function of thrust stand deflection, spring constant, and natural frequency. No empirical corrections were required. The accuracy of the method was verified using a swinging impact pendulum. Momentum transfer data between the thrust stand and the pendulum were consistent to within 1%. Following initial calibrations, the stand was used to test a Lincoln Experimental Satellite (LES-8/9) thruster. The LES-8/9 system had a mass of approximately 7.5 kg, with a nominal thrust to weight ratio of 1.3 x 10(exp -5). A total of 34 single shot thruster pulses were individually measured. The average impulse bit per pulse was 266 microN-s, which was slightly less than the value of 300 microN-s published in previous reports on this device. Repetitive pulse measurements were performed similar to ordinary steady-state thrust measurements. The thruster was operated for 30 minutes at a repetition rate of 132 pulses per minute and yielded an average thrust of 573 microN. Using average thrust, the average impulse bit per pulse was estimated to be 260 microN-s, which was in agreement with the single shot data. Zero drift during the repetitive pulse test was found to be approximately 1% of the measured thrust.

Haag, Thomas W.

1995-01-01

130

Static Performance of Six Innovative Thrust Reverser Concepts for Subsonic Transport Applications: Summary of the NASA Langley Innovative Thrust Reverser Test Program  

NASA Technical Reports Server (NTRS)

The NASA Langley Configuration Aerodynamics Branch has conducted an experimental investigation to study the static performance of innovative thrust reverser concepts applicable to high-bypass-ratio turbofan engines. Testing was conducted on a conventional separate-flow exhaust system configuration, a conventional cascade thrust reverser configuration, and six innovative thrust reverser configurations. The innovative thrust reverser configurations consisted of a cascade thrust reverser with porous fan-duct blocker, a blockerless thrust reverser, two core-mounted target thrust reversers, a multi-door crocodile thrust reverser, and a wing-mounted thrust reverser. Each of the innovative thrust reverser concepts offer potential weight savings and/or design simplifications over a conventional cascade thrust reverser design. Testing was conducted in the Jet-Exit Test Facility at NASA Langley Research Center using a 7.9%-scale exhaust system model with a fan-to-core bypass ratio of approximately 9.0. All tests were conducted with no external flow and cold, high-pressure air was used to simulate core and fan exhaust flows. Results show that the innovative thrust reverser concepts achieved thrust reverser performance levels which, when taking into account the potential for system simplification and reduced weight, may make them competitive with, or potentially more cost effective than current state-of-the-art thrust reverser systems. All data gathered in this investigation are contained in the CD-ROM.

Asbury, Scott C.; Yetter, Jeffrey A.

2000-01-01

131

Static Performance of Six Innovative Thrust Reverser Concepts for Subsonic Transport Applications: Summary of the NASA Langley Innovative Thrust Reverser Test Program  

NASA Technical Reports Server (NTRS)

The NASA Langley Configuration Aerodynamics Branch has conducted an experimental investigation to study the static performance of innovative thrust reverser concepts applicable to high-bypass-ratio turbofan engines. Testing was conducted on a conventional separate-flow exhaust system configuration, a conventional cascade thrust reverser configuration, and six innovative thrust reverser configurations. The innovative thrust reverser configurations consisted of a cascade thrust reverser with porous fan-duct blocker, a blockerless thrust reverser, two core-mounted target thrust reversers, a multi-door crocodile thrust reverser, and a wing-mounted thrust reverser. Each of the innovative thrust reverser concepts offer potential weight savings and/or design simplifications over a conventional cascade thrust reverser design. Testing was conducted in the Jet-Exit Test Facility at NASA Langley Research Center using a 7.9%-scale exhaust system model with a fan-to-core bypass ratio of approximately 9.0. All tests were conducted with no external flow and cold, high-pressure air was used to simulate core and fan exhaust flows. Results show that the innovative thrust reverser concepts achieved thrust reverser performance levels which, when taking into account the potential for system simplification and reduced weight, may make them competitive with, or potentially more cost effective than current state-of-the-art thrust reverser systems.

Asbury, Scott C.; Yetter, Jeffrey A.

2000-01-01

132

Laser plasma thruster continuous thrust experiment  

NASA Astrophysics Data System (ADS)

The laser plasma thruster (LPT) is a new microthruster for small satellites. We report on development and testing of a prototype LPT. Some advantages of the LPT are: thruster voltage 4 V, mass less than 1 kg, power-to-thrust ratio 10 kW/newton and Isp up to 1000 seconds. Typical thrust level is 250 (mu) N with PVC fuel. Thrust of 1 mN is expected with energetic fuel. The pre-prototype continuous thrust experiment includes the laser mount and heat sink, lens mounts, and focusing mechanism, which are coupled to the target material transport mechanism. The target material is applied to a transparent plastic tape, and the laser is focused on a series of tracks on the tape. The tape drive hardware and laser drive electronics, are described, as well as the control and diagnostic software. Design, construction, and calibration of the thrust stand are described. During continuous operation, the exhaust plume is deflected in the direction of the moving tape. When the laser is operated in pulsed mode, the exhaust plume is perpendicular to the tape (parallel to the optical axis). This provides some thrust vector control.

Luke, James R.; Phipps, Claude R.; McDuff, G. Glen

2002-09-01

133

Robust nonlinear control of vectored thrust aircraft  

NASA Technical Reports Server (NTRS)

An interdisciplinary program in robust control for nonlinear systems with applications to a variety of engineering problems is outlined. Major emphasis will be placed on flight control, with both experimental and analytical studies. This program builds on recent new results in control theory for stability, stabilization, robust stability, robust performance, synthesis, and model reduction in a unified framework using Linear Fractional Transformations (LFT's), Linear Matrix Inequalities (LMI's), and the structured singular value micron. Most of these new advances have been accomplished by the Caltech controls group independently or in collaboration with researchers in other institutions. These recent results offer a new and remarkably unified framework for all aspects of robust control, but what is particularly important for this program is that they also have important implications for system identification and control of nonlinear systems. This combines well with Caltech's expertise in nonlinear control theory, both in geometric methods and methods for systems with constraints and saturations.

Doyle, John C.; Murray, Richard; Morris, John

1993-01-01

134

Thrust stand for low-thrust liquid pulsed rocket engines  

NASA Astrophysics Data System (ADS)

A thrust stand is developed for measuring the pulsed thrust generated by low-thrust liquid pulsed rocket engines. It mainly consists of a thrust dynamometer, a base frame, a connecting frame, and a data acquisition and processing system. The thrust dynamometer assembled with shear mode piezoelectric quartz sensors is developed as the core component of the thrust stand. It adopts integral shell structure. The sensors are inserted into unique double-elastic-half-ring grooves with an interference fit. The thrust is transferred to the sensors by means of static friction forces of fitting surfaces. The sensors could produce an amount of charges which are proportional to the thrust to be measured. The thrust stand is calibrated both statically and dynamically. The in situ static calibration is performed using a standard force sensor. The dynamic calibration is carried out using pendulum-typed steel ball impact technique. Typical thrust pulse is simulated by a trapezoidal impulse force. The results show that the thrust stand has a sensitivity of 25.832 mV/N, a linearity error of 0.24% FSO, and a repeatability error of 0.23% FSO. The first natural frequency of the thrust stand is 1245 Hz. The thrust stand can accurately measure thrust waveform of each firing, which is used for fine control of on-orbit vehicles in the thrust range of 5-20 N with pulse frequency of 50 Hz.

Xing, Qin; Zhang, Jun; Qian, Min; Jia, Zhen-yuan; Sun, Bao-yuan

2010-09-01

135

Classification of jet fuel properties by near-infrared spectroscopy using fuzzy rule-building expert systems and support vector machines.  

PubMed

Monitoring the changes of jet fuel physical properties is important because fuel used in high-performance aircraft must meet rigorous specifications. Near-infrared (NIR) spectroscopy is a fast method to characterize fuels. Because of the complexity of NIR spectral data, chemometric techniques are used to extract relevant information from spectral data to accurately classify physical properties of complex fuel samples. In this work, discrimination of fuel types and classification of flash point, freezing point, boiling point (10%, v/v), boiling point (50%, v/v), and boiling point (90%, v/v) of jet fuels (JP-5, JP-8, Jet A, and Jet A1) were investigated. Each physical property was divided into three classes, low, medium, and high ranges, using two evaluations with different class boundary definitions. The class boundaries function as the threshold to alarm when the fuel properties change. Optimal partial least squares discriminant analysis (oPLS-DA), fuzzy rule-building expert system (FuRES), and support vector machines (SVM) were used to build the calibration models between the NIR spectra and classes of physical property of jet fuels. OPLS-DA, FuRES, and SVM were compared with respect to prediction accuracy. The validation of the calibration model was conducted by applying bootstrap Latin partition (BLP), which gives a measure of precision. Prediction accuracy of 97 ± 2% of the flash point, 94 ± 2% of freezing point, 99 ± 1% of the boiling point (10%, v/v), 98 ± 2% of the boiling point (50%, v/v), and 96 ± 1% of the boiling point (90%, v/v) were obtained by FuRES in one boundaries definition. Both FuRES and SVM obtained statistically better prediction accuracy over those obtained by oPLS-DA. The results indicate that combined with chemometric classifiers NIR spectroscopy could be a fast method to monitor the changes of jet fuel physical properties. PMID:21073794

Xu, Zhanfeng; Bunker, Christopher E; Harrington, Peter de B

2010-11-01

136

Environmental Thrust Handbook.  

ERIC Educational Resources Information Center

This handbook was prepared as a tool to assist U. S. Department of Agriculture (USDA) employees coordinate their resources and efforts to help people improve their environment. Twenty-two projects are outlined as potential environmental thrusts at the community level. It is the role of USDA employees to encourage and assist, in every way possible,…

Department of Agriculture, Washington, DC.

137

RESEARCH ARTICLE1 2 Evaluation of thrust measurement techniques for dielectric  

E-print Network

voltages with 22 the measured thrust increasing as much as 20 % for a six 23 times reduction in the length), landing gears (Thomas et al. 2005), airfoils 68(Little et al. 2010; Post and Corke 2004), turbulent jets A

Roy, Subrata

138

Effects of thrust reversing in ground proximity  

NASA Technical Reports Server (NTRS)

The changes in stability and control characteristics encountered by a thrust reversing aircraft during its final approach, landing, and ground roll are described. These changes include a strong pitch-up accompanied by the loss of horizontal tail and aileron control effectiveness. The magnitude of reverser induced changes in ground effect are much larger than corresponding changes in free air. Some unexpected unsteady motions exhibited in wind tunnel by an aircraft model with reversers operating in ground proximity are also described. The cause of this oscillatory behavior was determined to be an unsteady interaction between the wall jets formed by impingement of reverser jets on the ground and the on-coming free stream. Time histories of rolling moments measured by the wind tunnel balance or support system were removed and frequencies were scaled by Strouhal number to full scale. Corrected time series were used to simulate the motion of a fighter aircraft with thrust reversers in ground effect. The simulation predicted large roll angles and nose down attitude at touchdown. Some phenomena of jet attachment to solid surfaces are discussed and areas for future research are recommended.

Joshi, P. B.; Hughes, R. V.

1987-01-01

139

Field of Flow About a Jet and Effect of Jets on Stability of Jet-Propelled Airplanes  

NASA Technical Reports Server (NTRS)

A theoretical investigation was conducted on jet-induced flow deviation. Analysis is given of flow inclination induced outside cold and hot jets and jet deflection caused by angle of attack. Applications to computation of effects of jet on longitudinal stability and trim are explained. Effect of jet temperature on flow inclination was found small when thrust coefficient is used as criterion for similitude. The average jet-induced downwash over tail plane was obtained geometrically.

Ribner, Herbert S.

1946-01-01

140

Thrust balancing and cooling system  

Microsoft Academic Search

The method is described of balancing the thrust loads imposed on components in a gas turbine engine of the type that includes a compressor and turbine which gas turbine engine operates over a given operating envelope including low thrust to high thrust producing capacity including: enclosing a chamber with components having pressure exposing surfaces within the engine between the compressor

R. F. Brodell; V. P. Laurello

1987-01-01

141

Transient flow thrust prediction for an ejector propulsion concept  

NASA Technical Reports Server (NTRS)

A method for predicting transient thrust augmenting ejector characteristics is introduced. The analysis blends classic self-similar turbulent jet descriptions with a mixing region control volume analysis to predict transient effects in a new way. Details of the theoretical foundation, the solution algorithm, and sample calculations are given.

Drummond, Colin K.

1989-01-01

142

Static Performance of a Wing-Mounted Thrust Reverser Concept  

NASA Technical Reports Server (NTRS)

An experimental investigation was conducted in the Jet-Exit Test Facility at NASA Langley Research Center to study the static aerodynamic performance of a wing-mounted thrust reverser concept applicable to subsonic transport aircraft. This innovative engine powered thrust reverser system is designed to utilize wing-mounted flow deflectors to produce aircraft deceleration forces. Testing was conducted using a 7.9%-scale exhaust system model with a fan-to-core bypass ratio of approximately 9.0, a supercritical left-hand wing section attached via a pylon, and wing-mounted flow deflectors attached to the wing section. Geometric variations of key design parameters investigated for the wing-mounted thrust reverser concept included flow deflector angle and chord length, deflector edge fences, and the yaw mount angle of the deflector system (normal to the engine centerline or parallel to the wing trailing edge). All tests were conducted with no external flow and high pressure air was used to simulate core and fan engine exhaust flows. Test results indicate that the wing-mounted thrust reverser concept can achieve overall thrust reverser effectiveness levels competitive with (parallel mount), or better than (normal mount) a conventional cascade thrust reverser system. By removing the thrust reverser system from the nacelle, the wing-mounted concept offers the nacelle designer more options for improving nacelle aero dynamics and propulsion-airframe integration, simplifying nacelle structural designs, reducing nacelle weight, and improving engine maintenance access.

Asbury, Scott C.; Yetter, Jeffrey A.

1998-01-01

143

Solar electric propulsion thrust subsystem development  

NASA Technical Reports Server (NTRS)

The Solar Electric Propulsion System developed under this program was designed to demonstrate all the thrust subsystem functions needed on an unmanned planetary vehicle. The demonstration included operation of the basic elements, power matching input and output voltage regulation, three-axis thrust vector control, subsystem automatic control including failure detection and correction capability (using a PDP-11 computer), operation of critical elements in thermal-vacuum-, zero-gravity-type propellant storage, and data outputs from all subsystem elements. The subsystem elements, functions, unique features, and test setup are described. General features and capabilities of the test-support data system are also presented. The test program culminated in a 1500-h computer-controlled, system-functional demonstration. This included simultaneous operation of two thruster/power conditioner sets. The results of this testing phase satisfied all the program goals.

Masek, T. D.

1973-01-01

144

V+jets production at the CMS  

E-print Network

Measurements of Vector Boson production in association with jets are presented, using p-p collision data at sqrt{s} = 7 TeV. The measurements presented include Z + jets azimuthal correlations, event shapes, vector boson + jets differential cross section measurements, hard double-parton scattering using W + jets events and electroweak Z + forward - backward jet production.

B. Bilin; for the CMS Collaboration

2014-10-22

145

Investigation of a Full-scale, Cascade-type Thrust Reverser  

NASA Technical Reports Server (NTRS)

A double set of turning vanes was carried inside the jet tailpipe. To produce reverse thrust, the tailpipe opens into two side sections and the turning vanes move outward to form a V-shaped cascade, which deflects the exhaust-gas flow. Forward and reverse net thrust were measured over a range of engine speeds with the airplane stationary. Taxi tests were made to determine the comparative stopping distances using wheel braking and reverse thrust separately, and a combination of both. The effect of turning-vane spacing on thrust-reverser performance was determined by scale-model tests using unheated air.

Kohl, Robert C; Algranti, Joseph S

1957-01-01

146

Axisymmetric and non-axisymmetric exhaust jet induced effects on a V/STOL vehicle design. Part 3: Experimental technique  

NASA Technical Reports Server (NTRS)

The jet induced effects of several exhaust nozzle configurations (axisymmetric, and vectoring/modulating varients) on the aeropropulsive performance of a twin engine V/STOL fighter design was determined. A 1/8 scale model was tested in an 11 ft transonic tunnel at static conditions and over a range of Mach Numbers from 0.4 to 1.4. The experimental aspects of the static and wind-on programs are discussed. Jet effects test techniques in general, fow through balance calibrations and tare force corrections, ASME nozzle thrust and mass flow calibrations, test problems and solutions are emphasized.

Schnell, W. C.

1982-01-01

147

Development of a two-dimensional dual pendulum thrust stand for Hall thrusters  

SciTech Connect

A two-dimensional dual pendulum thrust stand was developed to measure thrust vectors (axial and horizontal (transverse) direction thrusts) of a Hall thruster. A thruster with a steering mechanism is mounted on the inner pendulum, and thrust is measured from the displacement between inner and outer pendulums, by which a thermal drift effect is canceled out. Two crossover knife-edges support each pendulum arm: one is set on the other at a right angle. They enable the pendulums to swing in two directions. Thrust calibration using a pulley and weight system showed that the measurement errors were less than 0.25 mN (1.4%) in the main thrust direction and 0.09 mN (1.4%) in its transverse direction. The thrust angle of the thrust vector was measured with the stand using the thruster. Consequently, a vector deviation from the main thrust direction of {+-}2.3 deg. was measured with the error of {+-}0.2 deg. under the typical operating conditions for the thruster.

Nagao, N.; Yokota, S.; Komurasaki, K.; Arakawa, Y. [Department of Aeronautics and Astronautics, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Advanced Energy, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Aeronautics and Astronautics, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

2007-11-15

148

Calibration for Thrust and Airflow Measurements in the CE-22 Advanced Nozzle Test Facility  

NASA Technical Reports Server (NTRS)

CE-22 facility procedures and measurements for thrust and airflow calibration obtained with choked-flow ASME nozzles are presented. Six calibration nozzles are used at an inlet total pressure from 20 to 48 psia. Throat areas are from 9.9986 to 39.986 sq. in.. Throat Reynolds number varies from 1.8 to 7.9 million. Nozzle gross thrust coefficient (CFG) uncertainty is 0.25 to 0.75 percent, with smaller uncertainly generally for larger nozzles and higher inlet total pressure. Nozzle discharge coefficient (CDN) uncertainty is 0.15 percent or less for all the data. ASME nozzle calibrations need to be done before and after research model testing to achieve these uncertainties. In addition, facility capability in terms of nozzle pressure ratio (NPR) and nozzle airflow are determined. Nozzle pressure ratio of 50 or more is obtainable at 40 psia for throat areas between 20 and 30 sq. in.. Also presented are results for two of the ASME nozzles vectored at 10deg, a dead-weight check of the vertical (perpendicular to the jet axis) force measurement, a calibration of load cell forces for the effects of facility tank deflection with tank pressure, and the calibration of the metric-break labyrinth seal.

Werner, Roger A.; Wolter, John D.

2010-01-01

149

Low thrust vehicle concept study  

NASA Technical Reports Server (NTRS)

Low thrust chemical (hydrogen-oxygen) propulsion systems configured specifically for low acceleration orbit transfer of large space systems were defined. Results indicate that it is cost effective and least risk to combine the OTV and stowed spacecraft in a single 65 K Shuttle. The study shows that the engine for an optimized low thrust stage (1) does not require very low thrust; (2) 1-3 K thrust range appears optimum; (3) thrust transient is not a concern; (4) throttling probably not worthwhile; and (5) multiple thrusters complicate OTV/LSS design and aggravate LSS loads. Regarding the optimum vehicle for low acceleration missions, the single shuttle launch (LSS and expendable OTV) is most cost effective and least risky. Multiple shuttles increase diameter 20%. The space based radar structure short OTV (which maximizes space available for packaged LSS) favors use of torus tank. Propellant tank pressures/vapor residuals are little affected by engine thrust level or number of burns.

1980-01-01

150

Lateral dampers for thrust bearings  

NASA Technical Reports Server (NTRS)

The development of lateral damping schemes for thrust bearings was examined, ranking their applicability to various engine classes, selecting the best concept for each engine class and performing an in-depth evaluation. Five major engine classes were considered: large transport, military, small general aviation, turboshaft, and non-manrated. Damper concepts developed for evaluation were: curved beam, constrained and unconstrained elastomer, hybrid boost bearing, hydraulic thrust piston, conical squeeze film, and rolling element thrust face.

Hibner, D. H.; Szafir, D. R.

1985-01-01

151

A numerical model for coupling between atomization and spray dynamics in liquid rocket thrust chambers  

Microsoft Academic Search

This paper describes a novel method of coupling the atomization and spray combustion processes encountered in coaxial injection elements of liquid rocket engine thrust chambers. This method is based on the Jet-Embedding technique in which the liquid jet core equations and the gas phase equations are solved separately. The liquid and gas phase solutions, however, are coupled through the boundary

M. G. Giridharan; J. G. Lee; A. Krishnan; A. J. Przekwas; Klaus Gross

1992-01-01

152

Editorial on Future Jet Technologies  

NASA Astrophysics Data System (ADS)

The jet engine is the prime flight controller in post-stall flight domains where conventional flight control fails, or when the engine prevents catastrophes in training, combat, loss of all airframe hydraulics (the engine retains its own hydraulics), loss of one engine, pilot errors, icing on the wings, landing gear and runway issues in takeoff and landing and in bad-whether recoveries. The scientific term for this revolutionary technology is "jet-steering", and in engineering practice - "thrust vectoring", or "TV". Jet-Steering in advanced fighter aircraft designs is integrated with stealth technology. The resulting classified Thrust-Vectoring-Stealth ("TVS") technology has generated a second jet-revolution by which all Air-&-Sea-Propulsion Science and R&D are now being reassessed. Classified F-22, X-47B/C and RQ-180 TVS-vehicles stand at the front of this revolution. But recent transfers of such sensitive technologies to South Korea and Japan [1-5], have raised various fundamental issues that are evaluated by this editorial-review. One, and perhaps a key conclusion presented here, means that both South Korea and Japan may have missed one of their air-&-sea defenses: To develop and field low-cost unmanned fleets of jet-drones, some for use with expensive, TVS-fighter aircraft in highly congested areas. In turn, the U.S., EU, Russia and China, are currently developing such fleets at various TVS levels and sizes. China, for instance, operates at least 15,000 drones ("UAVs") by 2014 in the civilian sector alone. All Chinese drones have been developed by at least 230 developers/manufacturers [1-16]. Mobile telecommunication of safe links between flyers and combat drones ("UCAVs") at increasingly deep penetrations into remote, congested areas, can gradually be purchased-developed-deployed and then operated by extant cader of tens of thousands "National Champion Flyers" who have already mastered the operation of mini-drones in free-to-all sport clubs under national competions and Awards. [Rule-13]. We also provide 26 references [17-43] to a different, unclassified technology that enhances TV-induced flight safety for passenger jets, turboprops and helicopters. It is based on patented stowed-away/emergency-deployed TV-kits added to fixed-configuration, subsonic exhaust nozzles of low thrust-to-weight ratio vehicles. Expected benefits include anti-terror recoveries from emergencies, like forced landing on unprepared runways or highways, or recoveries from all airframe-hydraulics-outs, asymmetric ice on wings, landing gear catastrophes, and recoveries from pilot errors and bad-whether incidents [Rule 9(7)]. Other TV technologies involve preventing catastrophes in speed and patrol boats, racing and regular cars/SUVs, buses and trucks. [Rule 9(8)] and faster helicopters [Rule 9(10)].

Gal-Or, Benjamin

2014-12-01

153

Static Thrust of an Annular Nozzle with a Concave Central Base  

NASA Technical Reports Server (NTRS)

A static test of an annular nozzle with a concave central base, producing a jet in which tangents to the jet streamlines at the exit converged toward a region on the axis of symmetry downstream of the exit, has indicated good thrust performance. A value of nozzle-flow coefficient only slightly less than unity indicates the internal loss to be small. Pressures on the concave central base are relatively large and positive, and a predictable portion of the total thrust of the jet is exerted on the central base.

Corson, Blake W., Jr.; Mercer, Charles E.

1960-01-01

154

Multiple jet impingement flowfields  

NASA Technical Reports Server (NTRS)

Attention is given to the prediction of lift-system-induced aerodynamic effects in lift-jet VTOL aircraft, considering both analytical fluid-dynamics models and an empirical database. The methodology takes into account the effects of aircraft geometry and orientation as well as height above ground, lift-jet vector and splay directions, jet exit-flow conditions, and nozzle exit geometry.

Kotansky, D. R.

1986-01-01

155

Micro thrust and heat generator  

DOEpatents

A micro thrust and heat generator has a means for providing a combustion fuel source to an ignition chamber of the micro thrust and heat generator. The fuel is ignited by a ignition means within the micro thrust and heat generator's ignition chamber where it burns and creates a pressure. A nozzle formed from the combustion chamber extends outward from the combustion chamber and tappers down to a narrow diameter and then opens into a wider diameter where the nozzle then terminates outside of said combustion chamber. The pressure created within the combustion chamber accelerates as it leaves the chamber through the nozzle resulting in pressure and heat escaping from the nozzle to the atmosphere outside the micro thrust and heat generator. The micro thrust and heat generator can be microfabricated from a variety of materials, e.g., of polysilicon, on one wafer using surface micromachining batch fabrication techniques or high aspect ratio micromachining techniques (LIGA).

Garcia, Ernest J. (Albuquerque, NM)

1998-01-01

156

Micro thrust and heat generator  

DOEpatents

A micro thrust and heat generator have a means for providing a combustion fuel source to an ignition chamber of the micro thrust and heat generator. The fuel is ignited by a ignition means within the micro thrust and heat generator`s ignition chamber where it burns and creates a pressure. A nozzle formed from the combustion chamber extends outward from the combustion chamber and tappers down to a narrow diameter and then opens into a wider diameter where the nozzle then terminates outside of said combustion chamber. The pressure created within the combustion chamber accelerates as it leaves the chamber through the nozzle resulting in pressure and heat escaping from the nozzle to the atmosphere outside the micro thrust and heat generator. The micro thrust and heat generator can be microfabricated from a variety of materials, e.g., of polysilicon, on one wafer using surface micromachining batch fabrication techniques or high aspect ratio micromachining techniques (LIGA). 30 figs.

Garcia, E.J.

1998-11-17

157

Effects of internal yaw-vectoring devices on the static performance of a pitch-vectoring nonaxisymmetric convergent-divergent nozzle  

NASA Technical Reports Server (NTRS)

An investigation was conducted in the static test facility of the Langley 16-Foot Transonic Tunnel to evaluate the internal performance of a nonaxisymmetric convergent divergent nozzle designed to have simultaneous pitch and yaw thrust vectoring capability. This concept utilized divergent flap deflection for thrust vectoring in the pitch plane and flow-turning deflectors installed within the divergent flaps for yaw thrust vectoring. Modifications consisting of reducing the sidewall length and deflecting the sidewall outboard were investigated as means to increase yaw-vectoring performance. This investigation studied the effects of multiaxis (pitch and yaw) thrust vectoring on nozzle internal performance characteristics. All tests were conducted with no external flow, and nozzle pressure ratio was varied from 2.0 to approximately 13.0. The results indicate that this nozzle concept can successfully generate multiaxis thrust vectoring. Deflection of the divergent flaps produced resultant pitch vector angles that, although dependent on nozzle pressure ratio, were nearly equal to the geometric pitch vector angle. Losses in resultant thrust due to pitch vectoring were small or negligible. The yaw deflectors produced resultant yaw vector angles up to 21 degrees that were controllable by varying yaw deflector rotation. However, yaw deflector rotation resulted in significant losses in thrust ratios and, in some cases, nozzle discharge coefficient. Either of the sidewall modifications generally reduced these losses and increased maximum resultant yaw vector angle. During multiaxis (simultaneous pitch and yaw) thrust vectoring, little or no cross coupling between the thrust vectoring processes was observed.

Asbury, Scott C.

1993-01-01

158

Experimental results for a two-dimensional supersonic inlet used as a thrust deflecting nozzle  

NASA Technical Reports Server (NTRS)

Nearly all supersonic V/STOL aircraft concepts are dependent on the thrust deflecting capability of a nozzle. In one unique concept, referred to as the reverse flow dual fan, not only is there a thrust deflecting nozzle for the fan and core engine exit flow, but because of the way the propulsion system operates during vertical takeoff and landing, the supersonic inlet is also used as a thrust deflecting nozzle. This paper presents results of an experimental study to evaluate the performance of a supersonic inlet used as a thrust deflecting nozzle for this reverse flow dual fan concept. Results are presented in terms of nozzle thrust coefficient and thrust vector angle for a number of inlet/nozzle configurations. Flow visualization and nozzle exit flow survey results are also shown.

Johns, Albert L.; Burstadt, Paul L.

1984-01-01

159

Secondary Production of Massive Quarks in Thrust  

E-print Network

We present a factorization framework that takes into account the production of heavy quarks through gluon splitting in the thrust distribution for e+ e- --> hadrons. The explicit factorization theorems and some numerical results are displayed in the dijet region where the kinematic scales are widely separated, which can be extended systematically to the whole spectrum. We account for the necessary two-loop matrix elements, threshold corrections, and include resummation up to N3LL order. We include nonperturbative power corrections through a field theoretical shape function, and remove the O(Lambda_QCD) renormalon in the partonic soft function by appropriate mass-dependent subtractions. Our results hold for any value of the quark mass, from an infinitesimally small (merging to the known massless result) to an infinitely large one (achieving the decoupling limit). This is the first example of an application of a variable flavor number scheme to final state jets.

Hoang, Andre H; Pietrulewicz, Piotr

2014-01-01

160

In-flight thrust determination  

NASA Technical Reports Server (NTRS)

The major aspects of processes that may be used for the determination of in-flight thrust are reviewed. Basic definitions are presented as well as analytical and ground-test methods for gathering data and calculating the thrust of the propulsion system during the flight development program of the aircraft. Test analysis examples include a single-exhaust turbofan, an intermediate-cowl turbofan, and a mixed-flow afterburning turbofan.

Abernethy, Robert B.; Adams, Gary R.; Ascough, John C.; Baer-Riedhart, Jennifer L.; Balkcom, George H.; Biesiadny, Thomas

1986-01-01

161

Micro thrust and heat generator  

SciTech Connect

The present invention relates generally to micromachines such as microengines or micromotors. More specifically, the invention is directed to a micro rocket which functions as a source of heat and thrust, and utilizes chemical energy to drive or power micromechanical apparatuses. The invention is adaptable to applications involving defense, bio-medical, manufacturing, consumer product, aviation, automotive, computer, inspection, and safety systems. A micro thrust and heat generator has a means for providing a combustion fuel source to an ignition chamber of the micro thrust and heat generator. The fuel is ignited by a ignition means within the micro thrust and heat generator`s ignition chamber where it burns and creates a pressure. A nozzle formed from the combustion chamber extends outward from the combustion chamber and tappers down to a narrow diameter and then opens into a wider diameter where the nozzle then terminates outside of said combustion chamber. The pressure created within the combustion chamber accelerates as it leaves the chamber through the nozzle resulting in pressure and heat escaping from the nozzle to the atmosphere outside the micro thrust and heat generator. The micro thrust and heat generator can be microfabricated from a variety of materials, e.g., of polysilicon, on one wafer using surface micromachining batch fabrication techniques or high aspect ratio micromachine techniques (LIGA).

Garcia, E.J.

1995-12-31

162

Prediction of thrusting sequences in accretionary wedges  

Microsoft Academic Search

The main objective is to determine the three stages of the life of a thrust in an accretionary wedge which are the onset of thrusting along its ramp, the development with the construction of the relief, and the arrest because of the onset of another thrusting event. A simple kinematics is proposed for the geometry of the developing thrust fold

N. Cubas; Y. M. Leroy; B. Maillot

2008-01-01

163

Uncertainty of in-flight thrust determination  

NASA Technical Reports Server (NTRS)

Methods for estimating the measurement error or uncertainty of in-flight thrust determination in aircraft employing conventional turbofan/turbojet engines are reviewed. While the term 'in-flight thrust determination' is used synonymously with 'in-flight thrust measurement', in-flight thrust is not directly measured but is determined or calculated using mathematical modeling relationships between in-flight thrust and various direct measurements of physical quantities. The in-flight thrust determination process incorporates both ground testing and flight testing. The present text is divided into the following categories: measurement uncertainty methodoogy and in-flight thrust measurent processes.

Abernethy, Robert B.; Adams, Gary R.; Steurer, John W.; Ascough, John C.; Baer-Riedhart, Jennifer L.; Balkcom, George H.; Biesiadny, Thomas

1986-01-01

164

Predicted flight characteristics of the augmentor wing jet STOL research aircraft  

NASA Technical Reports Server (NTRS)

An existing deHavilland C-8A airplane has been modified into an augmentor wing flight test vehicle. Research objectives are to verify the augmentor flap concept and to produce data for STOL airworthiness criteria. The Modified C-8A provides the means for jet-STOL flight research down to a 60 knot approach speed. The airplane has a high thrust-to-weight ratio, high-lift flap system, vectored thrust, powerful flight controls, and lateral-directional stability augmentation system. Normal performance and handling qualities are expected to be satisfactory. Analysis and piloted simulator results indicate that stability and control characteristics in conventional flight are rated satisfactory. Handling qualities in the STOL regime are also generally satisfactory, although pilot workload is high about the longitudinal axis.

Spitzer, R. E.

1972-01-01

165

Direct measurement of MPD thrust  

NASA Technical Reports Server (NTRS)

An integrally mounted accelerometer has been used to obtain direct thrust measurements during operation of a magnetoplasmadynamic (MPD) thruster. The structural oscillations which can mask the accelerometer output have been ameliorated by stiffening the thruster to increase the lowest resonant frequency above the 1kHz region of interest. In addition, signal conditioning is used to provide a high signal-to-noise accelerometer output waveform. Impulse response measurement of the thruster frequency response function has proven to be an effective means of selecting the signal filter and estimating measurement errors. Comparison of the total impulse derived from the accelerometer output with that from a swinging arm thrust stand indicates 3 percent agreement, providing some confidence in the viability of the accelerometer thrust measurement technique.

Berg, J. M.; Kelly, A. J.; Jahn, R. G.

1984-01-01

166

Low thrust propulsion literature survey  

NASA Technical Reports Server (NTRS)

A literature search was performed to investigate the area of low thrust propulsion. In an effort to evaluate this technology, a number of articles, obtained through the use of the NASA-RECON database, were collected and categorized. The study indicates that although much was done, particularly in the 1960's and 1970's, more can be done in the area of practical navigation and guidance. It is suggested that the older studies be reinvestigated to see what potential there exists for future low thrust applications.

Monroe, Darrel

1989-01-01

167

Pulsed Electric Propulsion Thrust Stand Calibration Method  

NASA Technical Reports Server (NTRS)

The evaluation of the performance of any propulsion device requires the accurate measurement of thrust. While chemical rocket thrust is typically measured using a load cell, the low thrust levels associated with electric propulsion (EP) systems necessitate the use of much more sensitive measurement techniques. The design and development of electric propulsion thrust stands that employ a conventional hanging pendulum arm connected to a balance mechanism consisting of a secondary arm and variable linkage have been reported in recent publications by Polzin et al. These works focused on performing steady-state thrust measurements and employed a static analysis of the thrust stand response. In the present work, we present a calibration method and data that will permit pulsed thrust measurements using the Variable Amplitude Hanging Pendulum with Extended Range (VAHPER) thrust stand. Pulsed thrust measurements are challenging in general because the pulsed thrust (impulse bit) occurs over a short timescale (typically 1 micros to 1 millisecond) and cannot be resolved directly. Consequently, the imparted impulse bit must be inferred through observation of the change in thrust stand motion effected by the pulse. Pulsed thrust measurements have typically only consisted of single-shot operation. In the present work, we discuss repetition-rate pulsed thruster operation and describe a method to perform these measurements. The thrust stand response can be modeled as a spring-mass-damper system with a repetitive delta forcing function to represent the impulsive action of the thruster.

Wong, Andrea R.; Polzin, Kurt A.; Pearson, J. Boise

2011-01-01

168

Thrust balancing and cooling system  

SciTech Connect

The method is described of balancing the thrust loads imposed on components in a gas turbine engine of the type that includes a compressor and turbine which gas turbine engine operates over a given operating envelope including low thrust to high thrust producing capacity including: enclosing a chamber with components having pressure exposing surfaces within the engine between the compressor and turbine and including sealing structure attached to the components such that the sealing structure includes axially disposed seals which seals have a known leakage characteristic, supplying air from the compressor to leak into the enclosed chamber through at least one of the seals' structure, and the pressure of the air varying in a relationship in the operating envelope, bleeding the air from the enclosed chamber in accordance with a predetermined schedule according to the operating envelope of the engine so that the pressure acting on pressure exposed surfaces of the components balances the thrust loads generated by the compressor and turbine of the engine while operating over its operating envelope.

Brodell, R.F.; Laurello, V.P.

1987-03-31

169

Thrust reverser with variable nozzle  

NASA Technical Reports Server (NTRS)

A thrust reverser is provided for both modulating and reversing bypass flow discharged from a fan through a bypass duct of a turbofan gas turbine engine. The reverser includes an aft cowl joined to a forward cowl and having an aft end surrounding a core engine to define a discharge fan nozzle of minimum flow throat area. The aft cowl is axially translatable relative to the forward cowl from a first position fully retracted against the forward cowl, to a second position partially extended from the forward cowl, and to a third position fully extended from the forward cowl. A plurality of cascade turning vanes are disposed between the forward and aft cowls, and a plurality of thrust reversing deflector doors are pivotally mounted to the aft cowl and bound the bypass duct. The deflector doors are selectively deployed from a stowed position corresponding with the first and second positions of the aft cowl for allowing unrestricted flow of the bypass flow through the fan nozzle. The doors also have a deployed position corresponding with the third position of the aft cowl for substantially deflecting the bypass flow from discharging through the fan nozzle to discharging through the cascade vanes for effecting thrust reverse. Axial translation of the aft cowl between the first and second positions varies flow area of the fan nozzle to vary thrust effected by the discharged bypass flow.

Butler, Lawrence (Inventor)

1997-01-01

170

Experimental performance of cascade thrust reversers at forward velocity  

NASA Technical Reports Server (NTRS)

A series of static and wind tunnel tests were performed on four cowl cascade thrust reverser configurations which had various reversed jet emission patterns applicable to an externally blown flap STOL aircraft. The work was performed using a model fan which was 14.0 cm in diameter and passed a fan mass flow of 2.49 kg/sec at an approximate fan pressure ratio of 1.22 and fan corrected rotational speed of 35,800 rpm. The tests demonstrated that the reingestion of fan flow significantly reduced the reverser efficiency and that the thrust reverser efficiency was improved by reducing the reversed jet azimuthal emmission angle. The reverser efficiency at STOL landing speeds was as high as 0.95; however, configurations with lateral emission were adversely affected by yawing the nacelle at forward velocity. Measurements of the internal static pressure at the stator exit showed significant increases in the local static pressure for configurations with reduced jet emission angles.

Dietrich, D. A.; Luidens, R. W.

1973-01-01

171

Stress, strain, and fault behavior at a thrust ramp: Insights from the Naukluft thrust, Namibia  

E-print Network

where shear and/or normal stress on a fault may change, as compared to thrust flats. In addition, faultStress, strain, and fault behavior at a thrust ramp: Insights from the Naukluft thrust, Namibia Ã?ke Accepted 2 November 2013 Available online 13 November 2013 Keywords: Fold-and-thrust belts Carbonate fault

172

The application of parameter estimation to flight measurements to obtain lateral-directional stability derivatives of an augmented jet-flap STOL airplane  

NASA Technical Reports Server (NTRS)

Flight experiments with an augmented jet flap STOL aircraft provided data from which the lateral directional stability and control derivatives were calculated by applying a linear regression parameter estimation procedure. The tests, which were conducted with the jet flaps set at a 65 deg deflection, covered a large range of angles of attack and engine power settings. The effect of changing the angle of the jet thrust vector was also investigated. Test results are compared with stability derivatives that had been predicted. The roll damping derived from the tests was significantly larger than had been predicted, whereas the other derivatives were generally in agreement with the predictions. Results obtained using a maximum likelihood estimation procedure are compared with those from the linear regression solutions.

Stephenson, J. D.

1983-01-01

173

Reversed cowl flap inlet thrust augmentor. [with adjustable airfoil  

NASA Technical Reports Server (NTRS)

An adjustable airfoil is described for varying the geometry of a jet inlet and an ejector inlet in a jet engine for providing thrust augmentation and noise reduction. The airfoil comprises essentially a plurality of segments which are extended radially outward and retracted relative to the longitudinal axis of the engine as a function of a change in the pressure differential between the upstream and downstream surfaces of the airfoil. A servo mechanism responsive to the change in the pressure differential is coupled to the airfoil to extend and retract the airfoil segments to maintain the pressure at a maximum on the downstream side of the airfoil relative to the pressure on the upstream side of the airfoil. At low speeds, such as at take-offs and landings, the airfoil is fully extended while at high speeds it is fully retracted.

Cheng, D. Y. (inventor)

1975-01-01

174

Analytical guidance for spacecraft relative motion under constant thrust using relative orbit elements  

NASA Astrophysics Data System (ADS)

Proximity control of modern nano-spacecraft often relies on low and discrete thrust engines that are characterized by low consumption, and generate on-off force profiles. New guidance solutions must take into account the nature of this type of orbital engines. This paper introduces novel analytical guidance solutions for spacecraft relative motion considering continuous, on-off thrust, and using relative orbit elements as a geometrical representation of the dynamics. The solutions provide the relative state vector at any given time, accommodating any thrust magnitude along the three directions of the relative frame, as well as generic activation times and durations. Relative orbit elements geometrically interpret key aspects of the relative motion, including for example, the relative ellipse size, and the evolution of its center in time. The new solutions provide the guidance designer with a direct visualization of the thrust effects on the relative motion geometry, offering new possibilities for analytical guidance in the presence of continuous thrust engines, such as low thrust engines on nano-spacecraft. The paper presents the analytical solutions, and tests their effectiveness using a sample thrust profile based on input-shaping, previously developed by one of the authors using classical Cartesian coordinates. The use of relative orbit elements shows substantial benefits and added simplicity with respect to Cartesian-based approaches, holding the promise for straightforward onboard spacecraft implementation. The software developed for this research will be available open source1

Bevilacqua, Riccardo; Lovell, Thomas Alan

2014-09-01

175

Tests of a D vented thrust deflecting nozzle behind a simulated turbofan engine  

NASA Technical Reports Server (NTRS)

A D vented thrust deflecting nozzle applicable to subsonic V/STOL aircraft was tested behind a simulated turbofan engine in the verticle thrust stand. Nozzle thrust, fan operating characteristics, nozzle entrance conditions, and static pressures were measured. Nozzle performance was measured for variations in exit area and thrust deflection angle. Six core nozzle configurations, the effect of core exit axial location, mismatched core and fan stream nozzle pressure ratios, and yaw vane presence were evaluated. Core nozzle configuration affected performance at normal and engine out operating conditions. Highest vectored nozzle performance resulted for a given exit area when core and fan stream pressure were equal. Its is concluded that high nozzle performance can be maintained at both normal and engine out conditions through control of the nozzle entrance Mach number with a variable exit area.

Watson, T. L.

1982-01-01

176

Measurement of the cross-section of high transverse momentum vector bosons reconstructed as single jets and studies of jet substructure in pp collisions at \\sqrt{s} = 7 TeV with the ATLAS detector  

NASA Astrophysics Data System (ADS)

This paper presents a measurement of the cross-section for high transverse momentum W and Z bosons produced in pp collisions and decaying to all-hadronic final states. The data used in the analysis were recorded by the ATLAS detector at the CERN Large Hadron Collider at a centre-of-mass energy of \\sqrt{s}=7 TeV and correspond to an integrated luminosity of 4.6 f{{b}-1}. The measurement is performed by reconstructing the boosted W or Z bosons in single jets. The reconstructed jet mass is used to identify the W and Z bosons, and a jet substructure method based on energy cluster information in the jet centre-of-mass frame is used to suppress the large multi-jet background. The cross-section for events with a hadronically decaying W or Z boson, with transverse momentum {{p}T}\\gt 320 GeV and pseudorapidity |? |\\lt 1.9, is measured to be {{? }W+Z}=8.5+/- 1.7 pb and is compared to next-to-leading-order calculations. The selected events are further used to study jet grooming techniques.

Aad, G.; Abajyan, T.; Abbott, B.; Abdallah, J.; Abdel Khalek, S.; Abdinov, O.; Aben, R.; Abi, B.; Abolins, M.; AbouZeid, O. S.; Abramowicz, H.; Abreu, H.; Abulaiti, Y.; Acharya, B. S.; Adamczyk, L.; Adams, D. L.; Addy, T. N.; Adelman, J.; Adomeit, S.; Adye, T.; Agatonovic-Jovin, T.; Aguilar-Saavedra, J. A.; Agustoni, M.; Ahlen, S. P.; Ahmadov, F.; Aielli, G.; Åkesson, T. P. A.; Akimoto, G.; Akimov, A. V.; Albert, J.; Albrand, S.; Alconada Verzini, M. J.; Aleksa, M.; Aleksandrov, I. N.; Alexa, C.; Alexander, G.; Alexandre, G.; Alexopoulos, T.; Alhroob, M.; Alimonti, G.; Alio, L.; Alison, J.; Allbrooke, B. M. M.; Allison, L. J.; Allport, P. P.; Allwood-Spiers, S. E.; Almond, J.; Aloisio, A.; Alon, R.; Alonso, A.; Alonso, F.; Alpigiani, C.; Altheimer, A.; Alvarez Gonzalez, B.; Alviggi, M. G.; Amako, K.; Amaral Coutinho, Y.; Amelung, C.; Ammosov, V. V.; Amor Dos Santos, S. P.; Amorim, A.; Amoroso, S.; Amram, N.; Amundsen, G.; Anastopoulos, C.; Ancu, L. S.; Andari, N.; Andeen, T.; Anders, C. F.; Anders, G.; Anderson, K. J.; Andreazza, A.; Andrei, V.; Anduaga, X. S.; Angelidakis, S.; Anger, P.; Angerami, A.; Anghinolfi, F.; Anisenkov, A. V.; Anjos, N.; Annovi, A.; Antonaki, A.; Antonelli, M.; Antonov, A.; Antos, J.; Anulli, F.; Aoki, M.; Aperio Bella, L.; Apolle, R.; Arabidze, G.; Aracena, I.; Arai, Y.; Arce, A. T. H.; Arguin, J.-F.; Argyropoulos, S.; Arik, E.; Arik, M.; Armbruster, A. J.; Arnaez, O.; Arnal, V.; Arslan, O.; Artamonov, A.; Artoni, G.; Asai, S.; Asbah, N.; Ask, S.; Åsman, B.; Asquith, L.; Assamagan, K.; Astalos, R.; Astbury, A.; Atkinson, M.; Atlay, N. B.; Auerbach, B.; Auge, E.; Augsten, K.; Aurousseau, M.; Avolio, G.; Azuelos, G.; Azuma, Y.; Baak, M. A.; Bacci, C.; Bach, A. M.; Bachacou, H.; Bachas, K.; Backes, M.; Backhaus, M.; Backus Mayes, J.; Badescu, E.; Bagiacchi, P.; Bagnaia, P.; Bai, Y.; Bailey, D. C.; Bain, T.; Baines, J. T.; Baker, O. K.; Baker, S.; Balek, P.; Balli, F.; Banas, E.; Banerjee, Sw; Bangert, A.; Bansal, V.; Bansil, H. S.; Barak, L.; Baranov, S. P.; Barber, T.; Barberio, E. L.; Barberis, D.; Barbero, M.; Barillari, T.; Barisonzi, M.; Barklow, T.; Barlow, N.; Barnett, B. M.; Barnett, R. M.; Baroncelli, A.; Barone, G.; Barr, A. J.; Barreiro, F.; Barreiro Guimarães da Costa, J.; Bartoldus, R.; Barton, A. E.; Bartos, P.; Bartsch, V.; Bassalat, A.; Basye, A.; Bates, R. L.; Batkova, L.; Batley, J. R.; Battistin, M.; Bauer, F.; Bawa, H. S.; Beau, T.; Beauchemin, P. H.; Beccherle, R.; Bechtle, P.; Beck, H. P.; Becker, K.; Becker, S.; Beckingham, M.; Beddall, A. J.; Beddall, A.; Bedikian, S.; Bednyakov, V. A.; Bee, C. P.; Beemster, L. J.; Beermann, T. A.; Begel, M.; Behr, K.; Belanger-Champagne, C.; Bell, P. J.; Bell, W. H.; Bella, G.; Bellagamba, L.; Bellerive, A.; Bellomo, M.; Belloni, A.; Belotskiy, K.; Beltramello, O.; Benary, O.; Benchekroun, D.; Bendtz, K.; Benekos, N.; Benhammou, Y.; Benhar Noccioli, E.; Benitez Garcia, J. A.; Benjamin, D. P.; Bensinger, J. R.; Benslama, K.; Bentvelsen, S.; Berge, D.; Bergeaas Kuutmann, E.; Berger, N.; Berghaus, F.; Berglund, E.; Beringer, J.; Bernard, C.; Bernat, P.; Bernius, C.; Bernlochner, F. U.; Berry, T.; Berta, P.; Bertella, C.; Bertolucci, F.; Besana, M. I.; Besjes, G. J.; Bessidskaia, O.; Besson, N.; Betancourt, C.; Bethke, S.; Bhimji, W.; Bianchi, R. M.; Bianchini, L.; Bianco, M.; Biebel, O.; Bieniek, S. P.; Bierwagen, K.; Biesiada, J.; Biglietti, M.; Bilbao De Mendizabal, J.; Bilokon, H.; Bindi, M.; Binet, S.; Bingul, A.; Bini, C.; Black, C. W.; Black, J. E.; Black, K. M.; Blackburn, D.; Blair, R. E.; Blanchard, J.-B.; Blazek, T.; Bloch, I.; Blocker, C.; Blum, W.; Blumenschein, U.; Bobbink, G. J.; Bobrovnikov, V. S.; Bocchetta, S. S.; Bocci, A.; Boddy, C. R.; Boehler, M.; Boek, J.; Boek, T. T.; Bogaerts, J. A.; Bogdanchikov, A. G.; Bogouch, A.; Bohm, C.; Bohm, J.; Boisvert, V.; Bold, T.; Boldea, V.; Boldyrev, A. S.; Bolnet, N. M.; Bomben, M.; Bona, M.; Boonekamp, M.; Borisov, A.; Borissov, G.; Borri, M.; Borroni, S.; Bortfeldt, J.; Bortolotto, V.; Bos, K.; Boscherini, D.; Bosman, M.; Boterenbrood, H.; Boudreau, J.; Bouffard, J.; Bouhova-Thacker, E. V.; Boumediene, D.; Bourdarios, C.; Bousson, N.; Boutouil, S.; Boveia, A.; Boyd, J.; Boyko, I. R.; Bozovic-Jelisavcic, I.; Bracinik, J.; Branchini, P.; Brandt, A.; Brandt, G.; Brandt, O.; Bratzler, U.; Brau, B.; Brau, J. E.; Braun, H. M.; Brazzale, S. F.; Brelier, B.; Brendlinger, K.; Brennan, A. J.; Brenner, R.; Bressler, S.; Bristow, K.; Bristow, T. M.; Britton, D.; Brochu, F. M.; Brock, I.; Brock, R.; Bromberg, C.; Bronner, J.; Brooijmans, G.; Brooks, T.; Brooks, W. K.; Brosamer, J.; Brost, E.; Brown, G.; Brown, J.; Bruckman de Renstrom, P. A.; Bruncko, D.; Bruneliere, R.; Brunet, S.; Bruni, A.; Bruni, G.; Bruschi, M.; Bryngemark, L.; Buanes, T.; Buat, Q.

2014-11-01

177

Omni-axis secondary injection thrust vector control system  

NASA Technical Reports Server (NTRS)

The concept, development, design study and preliminary analysis and layout of the required digital logic scheme to be used for injection valve control are presented. An application and optimization study of an Omni-Axis Secondary Injection Control System applicable to the proposed Space Shuttle Pressure Fed Engine is reported. Technical definition and analysis control procedures and test routines, as well as a supporting set of drawing sketches and reference manual, are enclosed.

Kirkley, D. J.

1973-01-01

178

Translation Optics for 30 cm Ion Engine Thrust Vector Control  

NASA Technical Reports Server (NTRS)

Data were obtained from a 30 cm xenon ion thruster in which the accelerator grid was translated in the radial plane. The thruster was operated at three different throttle power levels, and the accelerator grid was incrementally translated in the X, Y, and azimuthal directions. Plume data was obtained downstream from the thruster using a Faraday probe mounted to a positioning system. Successive probe sweeps revealed variations in the plume direction. Thruster perveance, electron backstreaming limit, accelerator current, and plume deflection angle were taken at each power level, and for each accelerator grid position. Results showed that the thruster plume could easily be deflected up to six degrees without a prohibitive increase in accelerator impingement current. Results were similar in both X and Y direction.

Haag, Thomas

2002-01-01

179

A numerical model for coupling between atomization and spray dynamics in liquid rocket thrust chambers  

NASA Astrophysics Data System (ADS)

This paper describes a novel method of coupling the atomization and spray combustion processes encountered in coaxial injection elements of liquid rocket engine thrust chambers. This method is based on the Jet-Embedding technique in which the liquid jet core equations and the gas phase equations are solved separately. The liquid and gas phase solutions, however, are coupled through the boundary conditions at the interface between the phases. The computational grid for the gas phase calculations are adapted to the shape of the liquid jet core. The axial variation of droplet sizes are calculated using a stability analysis appropriate for the atomization regime of liquid jet breakup. The predictions of this method have been validated with experimental data on low speed water jets. Using this method, calculations are performed for the SSME fuel preburner single injector flow field. The results obtained are in good agreement with the predictions of the volume-of-fluid method.

Giridharan, M. G.; Lee, J. G.; Krishnan, A.; Przekwas, A. J.; Gross, Klaus

1992-07-01

180

Evaluation Report: AGARD Fluid Dynamics Panel Symposium on Fluid Dynamics of Jets with Application to V\\/STOL  

Microsoft Academic Search

Topics covered include: (1) jet interactions with neighboring surfaces; (2) jet structure and development; (3) wind tunnel simulation of flow field, forces moments; (4) injection and thrust augmentation; (5) theoretical models and their assessments; (6) two dimensional wall jets; and (7) the use of a tracer gas method for measuring entrainment of an axisymmetric free jet. Conclusions of a panel

B. M. Spee

1982-01-01

181

Lightweight Chambers for Thrust Assemblies  

NASA Technical Reports Server (NTRS)

The Marshall Space Flight Center (MSFC) of the National Aeronautics and Space Administration (NASA) has successfully applied new materials and fabrication techniques to create actively cooled thrust chambers that operate 200-400 degrees hotter and weigh 50% lighter than conventional designs. In some vehicles, thrust assemblies account for as much as 20% of the engine weight. So, reducing the weight of these components and increasing their operating range will benefit many engines and vehicle designs, including Reusable Launch Vehicle (RLV) concepts. Obviously, copper and steel alloys have been used successfully for many years in the chamber components of thrust assemblies. Yet, by replacing the steel alloys with Polymer Matrix Composite (PMC) and/or Metal Matrix Composite (MMC) materials, design weights can be drastically reduced. In addition, replacing the traditional copper alloys with a Ceramic Matrix Composite (CMC) or an advanced copper alloy (Cu-8Cr-4Nb, also known as GRCop-84) significantly increases allowable operating temperatures. Several small MMC and PMC demonstration chambers have recently been fabricated with promising results. Each of these designs included GRCop-84 for the cooled chamber liner. These units successfully verified that designs over 50% lighter are feasible. New fabrication processes, including advanced casting technology and a low cost vacuum plasma spray (VPS) process, were also demonstrated with these units. Hot-fire testing at MSFC is currently being conducted on the chambers to verify increased operating temperatures available with the GRCop-84 liner. Unique CMC chamber liners were also successfully fabricated and prepared for hot-fire testing. Yet, early results indicate these CMC liners need significantly more development in order to use them in required chamber designs. Based on the successful efforts with the MMC and PMC concepts, two full size "lightweight" chambers are currently being designed and fabricated for hot-fire testing at MSFC in 2001. These "full size" chambers will be similar in size to those used on the X33 engine (RS2200). One will be fabricated with a MMC structural jacket, while the other uses a PMC jacket. Each will be designed for thrust levels of 15,000 pounds in an oxygen/hydrogen environment with liquid hydrogen coolant. Both chambers will use GRCop-84 for its channel wall liner. Each unit is expected to be at least 60% lighter than a conventional design with traditional materials. Hot-fire testing on the full size units in late 2001 will directly compare performance results between a conventional chamber design and these "lightweight" alternatives. The technology developed and demonstrated by this effort will not only benefit next generation RLV programs, but it can be applied to other existing and future engine programs, as well. Efforts were sponsored by the Advanced Space Transportation Program for RLV Focused Technologies. The task team was led by MSFC with additional members from NASA-Glenn Research Center and the Rocketdyne Division of The Boeing Company. Specific materials development and fabrication processes were provided by Aerojet, Lockheed Martin Astronautics, Composite Optics, Inc., Hyper-Therm, Ceramic Composites, Inc., MSE Technology Applications, and Plasma Processes, Inc.

Elam, Sandra K.; Lee, Jonathan; Holmes, Richard; Zimmerman, Frank; Effinger, Mike; Turner, James E. (Technical Monitor)

2001-01-01

182

Thrust bolting: roof bolt support apparatus  

DOEpatents

A method of installing a tensioned roof bolt in a borehole of a rock formation without the aid of a mechanical anchoring device or threaded tensioning threads by applying thrust to the bolt (19) as the bonding material (7') is curing to compress the strata (3) surrounding the borehole (1), and then relieving the thrust when the bonding material (7') has cured.

Tadolini, Stephen C. (Lakewood, CO); Dolinar, Dennis R. (Golden, CO)

1992-01-01

183

Flow Visualization in a Pocketed Thrust Washer  

Microsoft Academic Search

The objectives of this study were to experimentally and numerically investigate oil flow in surface-pocketed thrust washers. In order to achieve the experimental aspects of this investigation, a thrust washer test rig was designed and developed to visualize the lubricant flow at the contact interface. A novel approach for creating the pockets was developed to allow optical inspection of lubricant

Andrew T. Cross; Farshid Sadeghi; Lijun Cao; Richard G. Rateick Jr; Scott Rowan

2012-01-01

184

Spectral-tomographic methods and means of studying propellant flows of ion and plasma low-thrust engines  

NASA Astrophysics Data System (ADS)

Methods of spectral-tomographic diagnostics of ion and plasma jets in ion-plasma low-thrust engines are described. Methods that I have developed of 2D and 3D reconstruction of local values of temperature, concentration and absolute intensity in the ion-plasma jet are analyzed. Experimental setups of laboratory type for studying parameters of propellants of ion and plasma propulsion engines are described.

Filonin, O. V.

2015-01-01

185

Oxygen/Alcohol Dual Thrust RCS Engines  

NASA Technical Reports Server (NTRS)

A non-toxic dual thrust RCS engine offers significant operational, safety, and performance advantages to the space shuttle and the next generation RLVs. In this concept, a single engine produces two thrust levels of 25 and 870 lbf. The low thrust level is provided by the spark torch igniter, which, with the addition of 2 extra valves, can also be made to function as a vernier. A dual thrust RCS engine allows 38 verniers to be packaged more efficiently on a vehicle. These 38 vemiers improve translation and reduce cross coupling, thereby providing more pure roll, pitch, and yaw maneuvers of the vehicle. Compared to the 6 vemiers currently on the shuttle, the 38 dual thrust engines would be 25 to 40% more efficient for the same maneuvers and attitude control. The vernier thrust level also reduces plume impingement and contamination concerns. Redundancy is also improved, thereby improving mission success reliability. Oxygen and ethanol are benign propellants which do not create explosive reaction products or contamination, as compared to hypergolic propellants. These characteristics make dual-thrust engines simpler to implement on a non-toxic reaction control system. Tests at WSTF in August 1999 demonstrated a dual-thrust concept that is successful with oxygen and ethanol. Over a variety of inlet pressures and mixture ratios at 22:1 area ratio, the engine produced between 230 and 297 sec Isp, and thrust levels from 8 lbf. to 50 lbf. This paper describes the benefits of dual-thrust engines and the recent results from tests at WSTF.

Angstadt, Tara; Hurlbert, Eric

1999-01-01

186

Active Control of Supersonic Impinging Jets  

NASA Technical Reports Server (NTRS)

Experimental studies of supersonic impinging jet flows suggest that they are greatly influenced by the flow-acoustic interactions through a feedback mechanism. The self-sustained oscillations of the jet column observed in these flows result in high velocities in the ambient medium induced by the large-scale coherent vortical structures in the jet shear layers. As a consequence, the suck down force on the surface from which the jet is issuing can reach as high as 60% of the primary jet thrust. In addition, the overall sound pressure levels (OASPL) increase significantly relative to a free jet. To alleviate these undesirable flow and acoustic characteristics, a novel control technique using supersonic microjets is demonstrated. Sixteen supersonic microjets are placed around the circumference of the main jet at the nozzle exit to disrupt the feedback mechanism. As a result, significant lift loss recovery (approximately 50%) and reduced near field OASPL (approximately 7 dB) are observed.

Krothapalli, A.; Elavarasan, R.; Alvi, F.; Shih, C.; Wardwell, Doug (Technical Monitor)

2001-01-01

187

Jet Streams  

NSDL National Science Digital Library

This module describes the general characteristics of upper-level jet streams (Polar Jet, Subtropical Jet, and Tropical Easterly Jet) and two major tropical low-level wind maxima (Somali Jet, African Easterly Jet). Included are discussions of their formation, maintenance, influence on synoptic weather, and role in the general circulation.

Comet

2012-11-13

188

Friction losses in a lubricated thrust-loaded cageless angular-contract bearing  

NASA Technical Reports Server (NTRS)

The NASA spinning torque apparatus was modified to measure the spinning torque on a cageless ball thrust bearing. Friction torque was measured for thrust loads varying from 44.5 to 403 newtons (10 to 90 lb) at speeds of 1000, 2000, and 3000 rpm. Tests were conducted with di-2-ethylhexyl sebacate and a synthetic paraffinic oil. These tests were run with either oil jet lubrication or with a thin surface film of lubricant only. An analytical model which included rolling resistance was developed and extended from previous models for spinning torque and lubricant rheology. The model was extended by the inclusion of rolling resistance. The computed values were in fair agreement with the experimental results and confirmed previous hypotheses that a thin lubricant film gives minimum bearing torque and an oil jet flow of a viscous lubricant will result in considerable rolling torque in addition to the torque due to ball spin.

Townsend, D. P.; Allen, C. W.; Zaretsky, E. V.

1973-01-01

189

IEEE JOURNAL OF OCEANIC ENGINEERING, VOL. 33, NO. 2, APRIL 2008 123 Thrust Characterization of a Bioinspired Vortex Ring  

E-print Network

of underwater vehicles and robots. The actuators consist of a small cavity with a moving wall on one side, and Kamran Mohseni, Member, IEEE Abstract--A new type of thrusting technology, loosely inspired, with no net mass flux. Contin- uous operation of the actuator results in a synthetic jet. The actua- tors

Mohseni, Kamran

190

Ultra-High Bypass Ratio Jet Noise  

NASA Technical Reports Server (NTRS)

The jet noise from a 1/15 scale model of a Pratt and Whitney Advanced Ducted Propulsor (ADP) was measured in the United Technology Research Center anechoic research tunnel (ART) under a range of operating conditions. Conditions were chosen to match engine operating conditions. Data were obtained at static conditions and at wind tunnel Mach numbers of 0.2, 0.27, and 0.35 to simulate inflight effects on jet noise. Due to a temperature dependence of the secondary nozzle area, the model nozzle secondary to primary area ratio varied from 7.12 at 100 percent thrust to 7.39 at 30 percent thrust. The bypass ratio varied from 10.2 to 11.8 respectively. Comparison of the data with predictions using the current Society of Automotive Engineers (SAE) Jet Noise Prediction Method showed that the current prediction method overpredicted the ADP jet noise by 6 decibels. The data suggest that a simple method of subtracting 6 decibels from the SAE Coaxial Jet Noise Prediction for the merged and secondary flow source components would result in good agreement between predicted and measured levels. The simulated jet noise flight effects with wind tunnel Mach numbers up to 0.35 produced jet noise inflight noise reductions up to 12 decibels. The reductions in jet noise levels were across the entire jet noise spectra, suggesting that the inflight effects affected all source noise components.

Low, John K. C.

1994-01-01

191

Low thrust chemical rocket technology  

NASA Technical Reports Server (NTRS)

An on-going technology program to improve the performance of low thrust chemical rockets for spacecraft on-board propulsion applications is reviewed. Improved performance and lifetime is sought by the development of new predictive tools to understand the combustion and flow physics, introduction of high temperature materials and improved component designs to optimize performance, and use of higher performance propellants. Improved predictive technology is sought through the comparison of both local and global predictions with experimental data. Predictions are based on both the RPLUS Navier-Stokes code with finite rate kinetics and the JANNAF methodology. Data were obtained with laser-based diagnostics along with global performance measurements. Results indicate that the modeling of the injector and the combustion process needs improvement in these codes and flow visualization with a technique such as 2-D laser induced fluorescence (LIF) would aid in resolving issues of flow symmetry and shear layer combustion processes. High temperature material fabrication processes are under development and small rockets are being designed, fabricated, and tested using these new materials. Rhenium coated with iridium for oxidation protection was produced by the Chemical Vapor Deposition (CVD) process and enabled an 800 K increase in rocket operating temperature. Performance gains with this material in rockets using Earth storable propellants (nitrogen tetroxide and monomethylhydrazine or hydrazine) were obtained through component redesign to eliminate fuel film cooling and its associated combustion inefficiency while managing head end thermal soakback. Material interdiffusion and oxidation characteristics indicated that the requisite lifetimes of tens of hours were available for thruster applications. Rockets were designed, fabricated, and tested with thrusts of 22, 62, 440 and 550 N. Performance improvements of 10 to 20 seconds specific impulse were demonstrated. Higher performance propellants were evaluated: Space storable propellants, including liquid oxygen (LOX) as the oxidizer with nitrogen hydrides or hydrocarbon as fuels. Specifically, a LOX/hydrazine engine was designed, fabricated, and shown to have a 95 pct theoretical c-star which translates into a projected vacuum specific impulse of 345 seconds at an area ratio of 204:1. Further performance improvment can be obtained by the use of LOX/hydrogen propellants, especially for manned spacecraft applications, and specific designs must be developed and advanced through flight qualification.

Schneider, Steven J.

1992-01-01

192

Engineering Applications of Artificial Intelligence 16 (2003) 579593 Estimator design in jet engine applications  

E-print Network

Engineering Applications of Artificial Intelligence 16 (2003) 579­593 Estimator design in jet important in estimator design, cannot be directly applied. Generally, for practical jet engine applications these two problems are developed and applied to estimator design for jet engine thrust, stall margins

193

Simple thermodynamics of jet engines  

NASA Astrophysics Data System (ADS)

We use the first and second laws of thermodynamics to analyze the behavior of an ideal jet engine. Simple analytical expressions for the thermal efficiency, the overall efficiency, and the reduced thrust are derived. We show that the thermal efficiency depends only on the compression ratio r and on the velocity of the aircraft. The other two performance measures depend also on the ratio of the temperature at the turbine to the inlet temperature in the engine, T3/Ti. An analysis of these expressions shows that it is not possible to choose an optimal set of values of r and T3/Ti that maximize both the overall efficiency and thrust. We study how irreversibilities in the compressor and the turbine decrease the overall efficiency of jet engines and show that this effect is more pronounced for smaller T3/Ti.

Patrício, Pedro; Tavares, José M.

2010-08-01

194

Scaled Lunar Module Jet Erosion Experiments  

NASA Technical Reports Server (NTRS)

An experimental research program was conducted on the erosion of particulate surfaces by a jet exhaust. These experiments were scaled to represent the lunar module (LM) during landing. A conical cold-gas nozzle simulating the lunar module nozzle was utilized. The investigation was conducted within a large vacuum chamber by using gravel or glass beads as a simulated soil. The effects of thrust, descent speed, nozzle terminal height, particle size on crater size, and visibility during jet erosion were determined.

Land, Norman S.; Scholl, Harland F.

1966-01-01

195

Improvement of propeller static thrust estimation  

NASA Technical Reports Server (NTRS)

The problem of improving the performance estimation of propellers operating in the heavily loaded static thrust condition was studied. The Goldstein theory was assessed as it applies to propellers operating in the static thrust. A review of theoretical considerations is presented along with a summary of the attempts made to obtain a numerical solution. The chordwise pressure distribution was determined during operation at a tip speed of 500 ft/sec. Chordwise integration of the pressures leads to the spanwise load distribution and further integration would give the axial thrust.

Brusse, J.; Kettleborough, C. F.

1975-01-01

196

Collar nut and thrust ring  

DOEpatents

A collar nut comprises a hollow cylinder having fine interior threads at one end for threadably engaging a pump mechanical seal assembly and an inwardly depending flange at the other end. The flange has an enlarged portion with a groove for receiving an O-ring for sealing against the intrusion of pumpage from the exterior. The enlarged portion engages a thrust ring about the pump shaft for crushing a hard O-ring, such as a graphite O-ring. The hard O-ring seals the interior of the mechanical seal assembly and pump housing against the loss of lubricants or leakage of pumpage. The fine threads of the hollow cylinder provide the mechanical advantage for crushing the hard O-ring evenly and easily with a hand tool from the side of the collar nut rather than by tightening a plurality of bolts from the end and streamlines the exterior surface of the mechanical seal. The collar nut avoids the spatial requirements of bolt heads at the end of a seal and associated bolt head turbulence.

Lowery, Guy B. (Aiken, SC)

1991-01-01

197

Jet mass with a jet veto at two loops and the universality of non-global structure  

E-print Network

We investigate the exclusive jet mass distribution in e+e- events, defined with a veto on the out-of-jet radiation, at two-loop order. In particular, we calculate the two-loop soft function, which is required to describe this distribution in the threshold region. When combined with other ingredients using soft-collinear effective theory, this generates the complete singular distribution for jet thrust, the sum of the jet masses, at two-loop order. The result is in excellent agreement with full QCD. The integrated jet thrust distribution is found to depend in an intricate way on both the finite jet cone size, R, and the jet veto scale. The result clarifies the structure of the potentially large logarithms (both global and non- global) which arise in jet observables for the first time at this order. Somewhat surprisingly, we find that, in the small R limit, there is a precise and simple correspondence between the non-global contribution to the integrated jet thrust distribution and the previously calculated non-global contribution to the integrated hemisphere soft function, including subleading terms. This suggests that the small R limit may provide a useful expansion for studying other exclusive jet substructure observables.

Randall Kelley; Matthew D. Schwartz; Robert M. Schabinger; Hua Xing Zhu

2011-12-14

198

Twin Jet  

NASA Technical Reports Server (NTRS)

Many subsonic and supersonic vehicles in the current fleet have multiple engines mounted near one another. Some future vehicle concepts may use innovative propulsion systems such as distributed propulsion which will result in multiple jets mounted in close proximity. Engine configurations with multiple jets have the ability to exploit jet-by-jet shielding which may significantly reduce noise. Jet-by-jet shielding is the ability of one jet to shield noise that is emitted by another jet. The sensitivity of jet-by-jet shielding to jet spacing and simulated flight stream Mach number are not well understood. The current experiment investigates the impact of jet spacing, jet operating condition, and flight stream Mach number on the noise radiated from subsonic and supersonic twin jets.

Henderson, Brenda; Bozak, Rick

2010-01-01

199

Effect of varying internal geometry on the static performance of rectangular thrust-reverser ports  

NASA Technical Reports Server (NTRS)

An investigation has been conducted to evaluate the effects of several geometric parameters on the internal performance of rectangular thrust-reverser ports for nonaxisymmetric nozzles. Internal geometry was varied with a test apparatus which simulated a forward-flight nozzle with a single, fully deployed reverser port. The test apparatus was designed to simulate thrust reversal (conceptually) either in the convergent section of the nozzle or in the constant-area duct just upstream of the nozzle. The main geometric parameters investigated were port angle, port corner radius, port location, and internal flow blocker angle. For all reverser port geometries, the port opening had an aspect ratio (throat width to throat height) of 6.1 and had a constant passage area from the geometric port throat to the exit. Reverser-port internal performance and thrust-vector angles computed from force-balance measurements are presented.

Re, Richard J.; Mason, Mary L.

1987-01-01

200

Low-thrust chemical rocket engine study  

NASA Technical Reports Server (NTRS)

An analytical study evaluating thrust chamber cooling engine cycles and preliminary engine design for low thrust chemical rocket engines for orbit transfer vehicles is described. Oxygen/hydrogen, oxygen/methane, and oxygen/RP-1 engines with thrust levels from 444.8 N to 13345 N, and chamber pressures from 13.8 N/sq cm to 689.5 N/sq cm were evaluated. The physical and thermodynamic properties of the propellant theoretical performance data, and transport properties are documented. The thrust chamber cooling limits for regenerative/radiation and film/radiation cooling are defined and parametric heat transfer data presented. A conceptual evaluation of a number of engine cycles was performed and a 2224.1 N oxygen/hydrogen engine cycle configuration and a 2224.1 N oxygen/methane configuration chosen for preliminary engine design. Updated parametric engine data, engine design drawings, and an assessment of technology required are presented.

Shoji, J. M.

1981-01-01

201

Combination radial and thrust magnetic bearing  

NASA Technical Reports Server (NTRS)

A combination radial and thrust magnetic bearing is disclosed that allows for both radial and thrust axes control of an associated shaft. The combination radial and thrust magnetic bearing comprises a rotor and a stator. The rotor comprises a shaft, and first and second rotor pairs each having respective rotor elements. The stator comprises first and second stator elements and a magnet-sensor disk. In one embodiment, each stator element has a plurality of split-poles and a corresponding plurality of radial force coils and, in another embodiment, each stator element does not require thrust force coils, and radial force coils are replaced by double the plurality of coils serving as an outer member of each split-pole half.

Blumenstock, Kenneth A. (Inventor)

2002-01-01

202

Effects of an in-flight thrust reverser on the stability and control characteristics of a single-engine fighter airplane model  

NASA Technical Reports Server (NTRS)

The changes in thrust minus drag performance as well as longitudinal and directional stability and control characteristics of a single-engine jet aircraft attributable to an in-flight thrust reverser of the blocker-deflector door type were investigated in a 16-foot transonic wind tunnel. The longitudinal and directional stability data are presented. Test conditions simulated landing approach conditions as well as high speed maneuvering such as may be required for combat or steep descent from high altitude.

Mercer, C. E.; Maiden, D. L.

1972-01-01

203

GSFC Technology Thrusts and Partnership Opportunities  

NASA Technical Reports Server (NTRS)

This slide presentation reviews the technology thrusts and the opportunities to partner in developing software in support of the technological advances at the Goddard Space Flight Center (GSFC). There are thrusts in development of end-to-end software systems for mission data systems in areas of flight software, ground data systems, flight dynamic systems and science data systems. The required technical expertise is reviewed, and the supported missions are shown for the various areas given.

Le Moigne, Jacqueline

2010-01-01

204

Multiphysics Nuclear Thermal Rocket Thrust Chamber Analysis  

NASA Technical Reports Server (NTRS)

The objective of this effort is t o develop an efficient and accurate thermo-fluid computational methodology to predict environments for hypothetical thrust chamber design and analysis. The current task scope is to perform multidimensional, multiphysics analysis of thrust performance and heat transfer analysis for a hypothetical solid-core, nuclear thermal engine including thrust chamber and nozzle. The multiphysics aspects of the model include: real fluid dynamics, chemical reactivity, turbulent flow, and conjugate heat transfer. The model will be designed to identify thermal, fluid, and hydrogen environments in all flow paths and materials. This model would then be used to perform non- nuclear reproduction of the flow element failures demonstrated in the Rover/NERVA testing, investigate performance of specific configurations and assess potential issues and enhancements. A two-pronged approach will be employed in this effort: a detailed analysis of a multi-channel, flow-element, and global modeling of the entire thrust chamber assembly with a porosity modeling technique. It is expected that the detailed analysis of a single flow element would provide detailed fluid, thermal, and hydrogen environments for stress analysis, while the global thrust chamber assembly analysis would promote understanding of the effects of hydrogen dissociation and heat transfer on thrust performance. These modeling activities will be validated as much as possible by testing performed by other related efforts.

Wang, Ten-See

2005-01-01

205

W/Z+Jets and W/Z+Heavy Flavor Jets at the Tevatron  

E-print Network

The associated production of jets and vector bosons is an important process at hadron colliders. An overview over recent Tevatron vector boson+jets measurements is given with an emphasis on comparisons between data and the predictions of various theory models.

Nilsen, Henrik

2009-01-01

206

A thrust balance for low power hollow cathode thrusters  

NASA Astrophysics Data System (ADS)

A hanging thrust balance has been designed, manufactured and tested at the University of Southampton. The current design allows for direct steady thrust measurements ranging from 0.1 to 3 mN but this can be easily extended to measure thrust in a different range. Moreover the chosen balance design and the thrust measurement procedure allow for the cancellation of thermal drifts. The thrust balance was tested with a T6 hollow cathode thruster providing measurements with an uncertainty of about 9.7%. The thrust data were compared to those obtained with another direct thrust balance and they are in quantitative agreement—the maximum difference being only 6%.

Frollani, D.; Coletti, M.; Gabriel, S. B.

2014-06-01

207

Analytical design and simulation evaluation of an approach flight director system for a jet STOL aircraft  

NASA Technical Reports Server (NTRS)

A program was undertaken to develop design criteria and operational procedures for STOL transport aircraft. As part of that program, a series of flight tests shall be performed in an Augmentor Wing Jet STOL Aircraft. In preparation for the flight test programs, an analytical study was conducted to gain an understanding of the characteristics of the vehicle for manual control, to assess the relative merits of the variety of manual control techniques available with attitude and thrust vector controllers, and to determine what improvements can be made over manual control of the bare airframe by providing the pilot with suitable command guidance information and by augmentation of the bare airframe dynamics. The objective of the study is to apply closed-loop pilot/vehicle analysis techniques to the analysis of manual flight control of powered-lift STOL aircraft in the landing approach and to the design and experimental verification of an advanced flight director display.

Klein, R. H.; Hofmann, L. G.; Mcruer, D. T.

1974-01-01

208

Middle Proterozoic thrusting in central New Mexico  

SciTech Connect

Ductile thrust faults truncate contact-metamorphic aureoles surrounding two 1.4 Ga plutons in central New Mexico. The Priest quartz monzonite (1440 Ma) and Sandia granite (1420 Ma) are 50 km apart in the continuous Sandia/Manzano mountain chain. Thermobarometry and phase relations demonstrate that country-rock temperatures rose from 700 C toward the pluton, at pressure near 4 kb. The northern edge of this aureole is cut by the southeast-dipping ductile Monte Largo thrust fault. Prograde, greenschist-facies metamorphism of footwall rocks accompanied local retrogression of hangingwall rocks during thrusting. This second metamorphism took place at P-T conditions of 2-3 kb and 450-475 C. Another contact aureole surrounds the Sandia granite. Mafic rocks near the granite reflect amphibolite-facies conditions, whereas pelites display low-pressure contact assemblages. Quantitative temperatures increase from 500--750 C toward the granite, at pressures of 2.5--3.5 kb. The shallowly southeast-dipping Vincent Moore fault truncates the Sandia granite and the southern portion of its contact aureole. This ductile shear zone emplaced greenschist-facies rocks northwestward above the Sandia contact aureole. Footwall rocks were retrograded to the greenschist facies within 100 m of this fault; the retrograde phases are aligned parallel to the trace of the thrust. Metamorphic temperatures in hangingwall rocks (during thrusting ) were 400-475 C at pressures above 2.75 kb. Additional northwest-vergent ductile thrusts are found elsewhere in the mountain chain. This may represent the age of thrusting and of the related greenschist and the related greenschist-facies metamorphic overprint.

Grambling, J.A.; Thompson, A.G. (Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Earth and Planetary Sciences); Dallmeyer, R.D. (Univ. of Georgia, Athens, GA (United States). Dept. of Geology)

1992-01-01

209

Analysis of a Linear System for Variable-Thrust Control in the Terminal Phase of Rendezvous  

NASA Technical Reports Server (NTRS)

A linear system for applying thrust to a ferry vehicle in the 3 terminal phase of rendezvous with a satellite is analyzed. This system requires that the ferry thrust vector per unit mass be variable and equal to a suitable linear combination of the measured position and velocity vectors of the ferry relative to the satellite. The variations of the ferry position, speed, acceleration, and mass ratio are examined for several combinations of the initial conditions and two basic control parameters analogous to the undamped natural frequency and the fraction of critical damping. Upon making a desirable selection of one control parameter and requiring minimum fuel expenditure for given terminal-phase initial conditions, a simplified analysis in one dimension practically fixes the choice of the remaining control parameter. The system can be implemented by an automatic controller or by a pilot.

Hord, Richard A.; Durling, Barbara J.

1961-01-01

210

Scaled Lunar Module Jet Erosion Experiments  

NASA Technical Reports Server (NTRS)

Scaled Lunar Module Jet Erosion Experiments. An experimental research program was conducted on the erosion of particulate surfaces by a jet exhaust. These experiments were scaled to represent the lunar module (LM) during landing. A conical cold-gas nozzle simulating the lunar module nozzle was utilized. The investigation was conducted within a large vacuum chamber by using gravel or glass beads as a simulated soil. The effects of thrust, descent speed, nozzle terminal height, particle size on crater size, and visibility during jet erosion were determined. [Entire movie available on DVD from CASI as Doc ID 20070031010. Contact help@sti.nasa.gov

1966-01-01

211

Experimental investigation of jet-induced loads on a flat plate in hover out-of-ground effect  

NASA Technical Reports Server (NTRS)

Effects of varying jet decay rate on jet-induced loads on a flat plate located in the plane of the jet exit perpendicular to the jet axis were investigated using a small-scale laboratory facility. Jet decay rate has been varied through use of two cylindrical centerbodies having either a flat or hemispherical tip, which were submerged various distances below the flat plate jet exit plane. Increased jet decay rate, caused by the presence of a center-body or plug in the jet nozzle, led to an increased jet-induced lift loss on the flat plate. Jet-induced lift losses reached 1 percent of the jet thrust for the quickest jet decay rates for plate areas equal to 100 times the effective jet exit area. The observed lift loss versus jet decay rate trend agreed well with results of previous investigations.

Kuhlman, J. M.; Warcup, R. W.

1979-01-01

212

Ouachita Mountain thrust front: An integrated approach to prospect analysis in thrust belts  

Microsoft Academic Search

The thrust front of the Ouachita Mountains in western Arkansas is defined by the prominent asymmetric Washburn anticline. Previously interpreted as a complexly thrust-faulted anticline, the feature has been reinterpreted as a delta or triangle structure based on integration of surface mapping from thematic mapper (TM) data with subsurface interpretation of seismic and well-log cross sections. The northern limb of

R. L. Dodge; M. A. Keeling; D. Cassiani

1990-01-01

213

Static internal performance of a single-engine onaxisymmetric-nozzle vaned-thrust-reverser design with thrust modulation capabilities  

NASA Technical Reports Server (NTRS)

An investigation has been conducted at wind-off conditions in the stati-test facility of the Langley 16-Foot Transonic Tunnel. The tests were conducted on a single-engine reverser configuration with partial and full reverse-thrust modulation capabilities. The reverser design had four ports with equal areas. These ports were angled outboard 30 deg from the vertical impart of a splay angle to the reverse exhaust flow. This splaying of reverser flow was intended to prevent impingement of exhaust flow on empennage surfaces and to help avoid inlet reingestion of exhaust gas when the reverser is integrated into an actual airplane configuration. External vane boxes were located directly over each of the four ports to provide variation of reverser efflux angle from 140 deg to 26 deg (measured forward from the horizontal reference axis). The reverser model was tested with both a butterfly-type inner door and an internal slider door to provide area control for each individual port. In addition, main nozzle throat area and vector angle were varied to examine various methods of modulating thrust levels. Other model variables included vane box configuration (four or six vanes per box), orientation of external vane boxes with respect to internal port walls (splay angle shims), and vane box sideplates. Nozzle pressure ratio was varied from 2.0 approximately 7.0.

Leavitt, L. D.; Burley, J. R., II

1985-01-01

214

Ejector Noise Suppression with Auxiliary Jet Injection  

NASA Technical Reports Server (NTRS)

An experimental program to reduce aircraft jet turbulence noise investigated the interaction of small auxiliary jets with a larger main jet. Significant reductions in the far field jet noise were obtained over a range of auxiliary jet pressures and flow rates when used in conjunction with an acoustically lined ejector. While the concept is similar to that of conventional ejector suppressors that use mechanical mixing devices, the present approach should improve thrust and lead to lower weight and less complex noise suppression systems since no hardware needs to be located in the main jet flow. A variety of auxiliary jet and ejector configurations and operating conditions were studied. The best conditions tested produced peak to peak noise reductions ranging from 11 to 16 dB, depending on measurement angle, for auxiliary jet mass flows that were 6.6% of the main jet flow with ejectors that were 8 times the main jet diameter in length. Much larger reductions in noise were found at the original peak frequencies of the unsuppressed jet over a range of far field measurement angles.

Berman, Charles H.; Andersen, Otto P., Jr.

1997-01-01

215

Extending acoustic data measured with small-scale supersonic model jets to practical aircraft exhaust jets  

Microsoft Academic Search

Modern military aircraft jet engines are designed with variable geometry nozzles to provide optimum thrust in different operating conditions within the flight envelope. However, the acoustic measurements for such nozzles are scarce, due to the cost involved in making full-scale measurements and the lack of details about the exact geometry of these nozzles. Thus the present effort at The Pennsylvania

Ching-Wen Kuo

2010-01-01

216

Annihilation of angular momentum bias during thrusting and spinning-up maneuvers  

NASA Technical Reports Server (NTRS)

During spinning-up and thrusting maneuvers of rockets and spacecraft, undesired transverse torques (from error sources such as thruster misalignment, center-of-mass offset and thruster mismatch) perturb the angular momentum vector from its original orientation. In this paper a maneuver scheme is presented which virtually annihilates the angular momentum vector bias, even though the magnitude and direction of the perturbing body-fixed torques are unknown. In the analysis it is assumed that the torques are small and constant and that the spacecraft or rocket can be approximated by a rigid body, which may be asymmetric. Typical maneuvers of the Galileo spacecraft are simulated to demonstrate the technique.

Longuski, J. M.; Kia, T.; Breckenridge, W. G.

1989-01-01

217

Oil-Free Turbomachinery Research Enhanced by Thrust Bearing Test Capability  

NASA Technical Reports Server (NTRS)

NASA Glenn Research Center s Oil-Free Turbomachinery research team is developing aircraft turbine engines that will not require an oil lubrication system. Oil systems are required today to lubricate rolling-element bearings used by the turbine and fan shafts. For the Oil-Free Turbomachinery concept, researchers combined the most advanced foil (air) bearings from industry with NASA-developed high-temperature solid lubricant technology. In 1999, the world s first Oil-Free turbocharger was demonstrated using these technologies. Now we are working with industry to demonstrate Oil-Free turbomachinery technology in a small business jet engine, the EJ-22 produced by Williams International and developed during Glenn s recently concluded General Aviation Propulsion (GAP) program. Eliminating the oil system in this engine will make it simpler, lighter (approximately 15 percent), more reliable, and less costly to purchase and maintain. Propulsion gas turbines will place high demands on foil air bearings, especially the thrust bearings. Up until now, the Oil-Free Turbomachinery research team only had the capability to test radial, journal bearings. This research has resulted in major improvements in the bearings performance, but journal bearings are cylindrical, and can only support radial shaft loads. To counteract axial thrust loads, thrust foil bearings, which are disk shaped, are required. Since relatively little research has been conducted on thrust foil air bearings, their performance lags behind that of journal bearings.

Bauman, Steven W.

2003-01-01

218

A microNewton thrust stand for average thrust measurement of pulsed microthruster  

NASA Astrophysics Data System (ADS)

A torsional thrust stand has been developed for the study of the average thrust for microNewton pulsed thrusters. The main body of the thrust stand mainly consists of a torsional balance, a pair of flexural pivots, a capacitive displacement sensor, a calibration assembly, and an eddy current damper. The behavior of the stand was thoroughly studied. The principle of thrust measurement was analyzed. The average thrust is determined as a function of the average equilibrium angle displacement of the balance and the spring stiffness. The thrust stand has a load capacity up to 10 kg, and it can theoretically measure the force up to 609.6 ?N with a resolution of 24.4 nN. The static calibrations were performed based on the calibration assembly composed of the multiturn coil and the permanent magnet. The calibration results demonstrated good repeatability (less than 0.68% FSO) and good linearity (less than 0.88% FSO). The assembly of the multiturn coil and the permanent magnet was also used as an exciter to simulate the microthruster to further research the performance of the thrust stand. Three sets of force pulses at 17, 33.5, and 55 Hz with the same amplitude and pulse width were tested. The repeatability error at each frequency was 7.04%, 1.78%, and 5.08%, respectively.

Zhou, Wei-Jing; Hong, Yan-Ji; Chang, Hao

2013-12-01

219

A microNewton thrust stand for average thrust measurement of pulsed microthruster.  

PubMed

A torsional thrust stand has been developed for the study of the average thrust for microNewton pulsed thrusters. The main body of the thrust stand mainly consists of a torsional balance, a pair of flexural pivots, a capacitive displacement sensor, a calibration assembly, and an eddy current damper. The behavior of the stand was thoroughly studied. The principle of thrust measurement was analyzed. The average thrust is determined as a function of the average equilibrium angle displacement of the balance and the spring stiffness. The thrust stand has a load capacity up to 10 kg, and it can theoretically measure the force up to 609.6 ?N with a resolution of 24.4 nN. The static calibrations were performed based on the calibration assembly composed of the multiturn coil and the permanent magnet. The calibration results demonstrated good repeatability (less than 0.68% FSO) and good linearity (less than 0.88% FSO). The assembly of the multiturn coil and the permanent magnet was also used as an exciter to simulate the microthruster to further research the performance of the thrust stand. Three sets of force pulses at 17, 33.5, and 55 Hz with the same amplitude and pulse width were tested. The repeatability error at each frequency was 7.04%, 1.78%, and 5.08%, respectively. PMID:24387476

Zhou, Wei-Jing; Hong, Yan-Ji; Chang, Hao

2013-12-01

220

Search for 3rd Generation Vector Leptoquarks in the Di-tau Di-jet Channel in Proton Antiproton Collisions at square root s = 1.96 TeV  

SciTech Connect

We search for third generation vector leptoquarks (V LQ3) produced in colliding p{bar p} beams operating at {radical}s = 1.96 TeV at the CDF experiment in Run II of the Fermilab Tevatron. We use 322 pb{sup -1} of data to search for the V LQ3 signal in the di-tau plus di-jet channel. For the first time, the full matrix element is used in the Monte Carlo simulation of this signal. With no events observed in the signal region, we set a 95% C.L. upper limit on the V LQ3 pair production cross section of {sigma} < 344fb, assuming Yang-Mills couplings and Br(V LQ3 {yields} b{tau}) = 1, and a lower limit on the V LQ3 mass of m{sub V LQ3} > 317 GeV=c{sup 2}. If theoretical uncertainties on the cross section are applied in the least favorable manner the results are {sigma} < 360fb and m{sub V LQ3} > 294 GeV=c{sup 2}. The Minimal coupling V LQ3 result is an upper limit on the cross section of {sigma} < 493fb ({sigma} < 610fb) and the lower limit on the mass is m{sub V LQ3} > 251 GeV=c{sup 2} (m{sub V LQ3} > 223 GeV=c{sup 2}) for the nominal (1{sigma} varied) theoretical expectation.

Forrester, Stanley Scott; /UC, Davis

2006-12-01

221

Emergency Flight Control Using Only Engine Thrust and Lateral Center-of-Gravity Offset: A First Look  

NASA Technical Reports Server (NTRS)

Normally, the damage that results in a total loss of the primary flight controls of a jet transport airplane, including all engines on one side, would be catastrophic. In response, NASA Dryden has conceived an emergency flight control system that uses only the thrust of a wing-mounted engine along with a lateral center-of-gravity (CGY) offset from fuel transfer. Initial analysis and simulation studies indicate that such a system works, and recent high-fidelity simulation tests on the MD-11 and B-747 suggest that the system provides enough control for a survivable landing. This paper discusses principles of flight control using only a wing engine thrust and CGY offset, along with the amount of CGY offset capability of some transport airplanes. The paper also presents simulation results of the throttle-only control capability and closed-loop control of ground track using computer-controlled thrust.

Burcham, Frank W., Jr.; Burken, John; Maine, Trindel A.; Bull, John

1997-01-01

222

Development of an indirect counterbalanced pendulum optical-lever thrust balance for micro- to millinewton thrust measurement  

NASA Astrophysics Data System (ADS)

This paper describes the design and testing of an indirect hanging pendulum thrust balance using a laser-optical-lever principle to provide micro- to millinewton thrust measurement for the development of electric propulsion systems. The design philosophy allows the selection of the total thrust range in order to maximize resolution through a counterbalanced pendulum principle, as well as passive magnetic damping in order to allow relatively rapid transient thrust measurement. The balance was designed for the purpose of hollow cathode microthruster characterization, but could be applied to other electric propulsion devices in the thrust range of micro- to millinewtons. An initial thrust characterization of the T5 hollow cathode is presented.

Grubiši?, A. N.; Gabriel, S. B.

2010-10-01

223

The thrust belts of Western North America  

Microsoft Academic Search

Most of the Basin and Range physiographic province of western North America is now believed to be part of the overthrust. The more obvious overthrust belt along the eastern edge of the Basin and Range Province is named the Sevier orogenic belt, where older rocks are observed thrust onto younger rocks. More detailed surface geological mapping, plus deep multiple-fold geophysical

1993-01-01

224

Jet noise suppression by porous plug nozzles  

NASA Technical Reports Server (NTRS)

Jet noise suppression data presented earlier by Maestrello for porous plug nozzles were supplemented by the testing of a family of nozzles having an equivalent throat diameter of 11.77 cm. Two circular reference nozzles and eight plug nozzles having radius ratios of either 0.53 or 0.80 were tested at total pressure ratios of 1.60 to 4.00. Data were taken both with and without a forward motion or coannular flow jet, and some tests were made with a heated jet. Jet thrust was measured. The data were analyzed to show the effects of suppressor geometry on nozzle propulsive efficiency and jet noise. Aerodynamic testing of the nozzles was carried out in order to study the physical features that lead to the noise suppression. The aerodynamic flow phenomena were examined by the use of high speed shadowgraph cinematography, still shadowgraphs, extensive static pressure probe measurements, and two component laser Doppler velocimeter studies. The different measurement techniques correlated well with each other and demonstrated that the porous plug changes the shock cell structure of a standard nozzle into a series of smaller, periodic cell structures without strong shock waves. These structures become smaller in dimension and have reduced pressure variations as either the plug diameter or the porosity is increased, changes that also reduce the jet noise and decrease thrust efficiency.

Bauer, A. B.; Kibens, V.; Wlezien, R. W.

1982-01-01

225

Kinematics-Based Mathematical Model for Deforming Thrust Wedges  

Microsoft Academic Search

Given the wealth of data concerning the kinematics of deforming fold-thrust belts (FTBs), first-order generalizations about\\u000a how the major strain components vary within a deforming thrust wedges are considered. These generally observed strain patterns\\u000a are used to constrain a general, kinematics-based, FTB-wedge model. We considered five strain components within a deforming\\u000a thrust sheet: (1) thrust-parallel simple shear, (2) horizontal contractional strain,

Matty Mookerjee; Gautam Mitra

2008-01-01

226

Supersonic wings with significant leading-edge thrust at cruise  

NASA Technical Reports Server (NTRS)

Experimental/theoretical correlations are presented which show that significant levels of leading-edge thrust are possible at supersonic speeds for certain planforms having the geometry to support the theoretical thrust-distribution potential. The new analytical process employed provides not only the level of leading-edge thrust attainable but also the spanwise distribution of both it and that component of full theoretical thrust which acts as vortex lift. Significantly improved aerodynamic performance in the moderate supersonic speed regime is indicated.

Robins, A. W.; Carlson, H. W.; Mack, R. J.

1980-01-01

227

EXPERIMENTAL VALIDATION OF A MARINE PROPELLER THRUST ESTIMATION SCHEME  

E-print Network

EXPERIMENTAL VALIDATION OF A MARINE PROPELLER THRUST ESTIMATION SCHEME Luca Pivano yvind N. Smogeli and Technology, Trondheim, Norway. Abstract: A thrust estimation scheme for a marine propeller has been experimen is formed by a nonlinear propeller torque observer and a mapping to generate the thrust from the observed

Johansen, Tor Arne

228

Thrust augmentation nozzle (TAN) concept for rocket engine booster applications  

Microsoft Academic Search

Aerojet used the patented thrust augmented nozzle (TAN) concept to validate a unique means of increasing sea-level thrust in a liquid rocket booster engine. We have used knowledge gained from hypersonic Scramjet research to inject propellants into the supersonic region of the rocket engine nozzle to significantly increase sea-level thrust without significantly impacting specific impulse. The TAN concept overcomes conventional

Scott Forde; Mel Bulman; Todd Neill

2006-01-01

229

Summary of Scale-Model Thrust-Reverser Investigation  

NASA Technical Reports Server (NTRS)

An investigation was undertaken to determine the characteristics of several basic types of thrust-reverser. Models of three types, target, tailpipe cascade, and ring cascade, were tested with unheated air. The effects of design variables on reverse-thrust performance, reversed-flow boundaries, and thrust modulation characteristics were determined.

Povolny, John H; Steffen, Fred W; Mcardle, Jack G

1957-01-01

230

A control-volume method for analysis of unsteady thrust augmenting ejector flows  

NASA Technical Reports Server (NTRS)

A method for predicting transient thrust augmenting ejector characteristics is presented. The analysis blends classic self-similar turbulent jet descriptions with a control volume mixing region discretization to solicit transient effects in a new way. Division of the ejector into an inlet, diffuser, and mixing region corresponds with the assumption of viscous-dominated phenomenon in the latter. Inlet and diffuser analyses are simplified by a quasi-steady analysis, justified by the assumptions that pressure is the forcing function in those regions. Details of the theoretical foundation, the solution algorithm, and sample calculations are given.

Drummond, Colin K.

1988-01-01

231

Rotating primary flow induction using jet-flapped blades  

NASA Technical Reports Server (NTRS)

A new concept in ejector design is examined using primary jets exiting from a free spinning bladed rotor. This concept stems from a continuing effort in the development of Rotary-Jet thrust augmentors at George Washington University (GWU). An analysis of a Rotary-Jet rotor with jet-flapped blades is presented, identifying design trends beneficial to its performance. An experimental investigation was conducted to demonstrate the potential of this new concept. Several combinations of blade and shroud geometries were designed, fabricated and tested. The results are presented and discussed. Despite crudeness of fabrication, the maximum thrust augmentations obtained ranged from 1.55 to 2.14. These results demonstrate that this device is superior to all ejector designs tested with similar conventional passive diffusing shrouds.

Cordier, Stephane J.

1989-01-01

232

Design, fabrication, and testing of a SMA hybrid composite jet engine chevron  

Microsoft Academic Search

Control of jet noise continues to be an important research topic. Exhaust nozzle chevrons have been shown to reduce jet noise, but parametric effects are not well understood. Additionally, thrust loss due to chevrons at cruise suggests significant benefit from deployable chevrons. The focus of this study is development of an active chevron concept for the primary purpose of parametric

Travis L. Turner; Randolph H. Cabell; Roberto J. Cano; Gary A. Fleming

2006-01-01

233

The computational design of a water jet propulsion spherical underwater vehicle  

Microsoft Academic Search

Underwater vehicles have become an important tool to develop oceans. The design of the shape, hardware circuit and software of a water jet propulsion spherical underwater vehicle was introduced, and the characteristics of water jet pump were presented. The design of the thruster and computation of the thrust was proposed, too. A desired movement result was achieved by the designed

Shuxiang Guo; Juan Du; Xiufen Ye; Rui Yan; Hongtao Gao

2011-01-01

234

[McWilliams, Possible Wind River Basin Thrust Fault]1 Evidence of a Possible 32-Mile-Wide Thrust Fault,  

E-print Network

[McWilliams, Possible Wind River Basin Thrust Fault]1 Evidence of a Possible 32-Mile-Wide Thrust Fault, Wind River Basin, Fremont County Wyoming Robert G. McWilliams, Professor Emeritus, Department Indian Meadows and lower Wind River Formations. Love (1987) described in detail this fold-thrust fault

Lee Jr., Richard E.

235

Low-thrust mission risk analysis.  

NASA Technical Reports Server (NTRS)

A computerized multi-stage failure process simulation procedure is used to evaluate the risk in a solar electric space mission. The procedure uses currently available thrust-subsystem reliability data and performs approximate simulations of the thrust subsystem burn operation, the system failure processes, and the retargetting operations. The application of the method is used to assess the risks in carrying out a 1980 rendezvous mission to Comet Encke. Analysis of the results and evaluation of the effects of various risk factors on the mission show that system component failure rates is the limiting factor in attaining a high mission reliability. But it is also shown that a well-designed trajectory and system operation mode can be used effectively to partially compensate for unreliable thruster performance.

Yen, C. L.; Smith, D. B.

1973-01-01

236

Thrust production by a mechanical swimming lamprey  

NASA Astrophysics Data System (ADS)

To develop a comprehensive model of lamprey locomotion, we use a robotic lamprey to investigate the formation of the wake structure, the shedding vorticity from the body, and the relationship between thrust production and pressure on the surface of the robot. The robot mimics the motion of living lamprey in steady swimming by using a programmable microcomputer to actuate 13 servomotors that produce a traveling wave along the length of the lamprey body. The amplitude of the phase-averaged surface pressure distribution along the centerline of the robot increases toward the tail, which is consistent with previous momentum balance experiments. This indicates that thrust is produced mainly at the tail. The phase relationship between the pressure signal and the vortex shedding from the tail is also examined, showing a clear connection between the location of vortex structures and the fluctuations of the pressure signal.

Leftwich, M. C.; Smits, A. J.

2011-05-01

237

Static Thrust Analysis of the Lifting Airscrew  

NASA Technical Reports Server (NTRS)

This report presents the results of a combined theoretical and experimental investigation conducted at the Georgia School of Technology on the static thrust of the lifting air screw of the type used in modern autogiros and helicopters. The theoretical part of this study is based on Glauert's analysis but certain modifications are made that further clarify and simplify the problem. Of these changes the elimination of the solidity as an independent parameter is the most important. The experimental data were obtained from tests on four rotor models of two, four, and five blades and, in general, agree quite well with the theoretical calculations. The theory indicates a method of evaluating scale effects on lifting air screws, and these corrections have been applied to the model results to derive general full-scale static thrust, torque, and figure-of-merit curves for constant-chord, constant-incidence rotors. Convenient charts are included that enable hovering flight performance to be calculated rapidly.

Knight, Montgomery; Hefner, Ralph A

1937-01-01

238

Advanced tube-bundle rocket thrust chamber  

NASA Technical Reports Server (NTRS)

An advanced rocket thrust chamber for future space application is described along with an improved method of fabrication. Potential benefits of the concept are improved cyclic life, reusability, and performance. Performance improvements are anticipated because of the enhanced heat transfer into the coolant which will enable higher chamber pressure in expander cycle engines. Cyclic life, reusability and reliability improvements are anticipated because of the enhanced structural compliance inherent in the construction. The method of construction involves the forming of the combustion chamber with a tube-bundle of high conductivity copper or copper alloy tubes, and the bonding of these tubes by an electroforming operation. Further, the method of fabrication reduces chamber complexity by incorporating manifolds, jackets, and structural stiffeners while having the potential for thrust chamber cost and weight reduction.

Kazaroff, John M.; Pavli, Albert J.

1990-01-01

239

NATURAL BARRIERS TARGETED THRUST FY 2004 PROJECTS  

SciTech Connect

This booklet contains project descriptions of work performed by the Department of Energy (DOE), Office of Civilian Radioactive Waste Management (OCRWM), Office of Science and Technology and International's (OST&I) Natural Barriers Targeted Thrust during Fiscal Year (FY) 2004. The Natural Barriers Targeted Thrust is part of OST&I's Science and Technology Program which supports the OCRWM mission to manage and dispose of high-level radioactive waste and spent nuclear fuel in a manner that protects health, safety, and the environment; enhances national and energy security; and merits public confidence. In general, the projects described will continue beyond FY 2004 assuming that the technical work remains relevant to the proposed Yucca Mountain Repository and sufficient funding is made available to the Science and Technology Program.

NA

2005-07-27

240

Low-thrust Isp sensitivity study  

NASA Technical Reports Server (NTRS)

A comparison of the cooling requirements and attainable specific impulse performance of engines in the 445 to 4448N thrust class utilizing LOX/RP-1, LOX/Hydrogen and LOX/Methane propellants is presented. The unique design requirements for the regenerative cooling of low-thrust engines operating at high pressures (up to 6894 kPa) were explored analytically by comparing single cooling with the fuel and the oxidizer, and dual cooling with both the fuel and the oxidizer. The effects of coolant channel geometry, chamber length, and contraction ratio on the ability to provide proper cooling were evaluated, as was the resulting specific impulse. The results show that larger contraction ratios and smaller channels are highly desirable for certain propellant combinations.

Schoenman, L.

1982-01-01

241

Pulsed thrust propellant reorientation - Concept and modeling  

NASA Technical Reports Server (NTRS)

The use of pulsed thrust to optimize the propellant reorientation process is proposed. The ECLIPSE code is used to study the performance of pulsed reorientation in small-scale and full-scale propellant tanks. A dimensional analysis of the process is performed and the resulting dimensionless groups are used to present and correlate the computational predictions of reorientation performance. Based on the results obtained from this study, it is concluded that pulsed thrust reorientation seems to be a feasible technique for optimizing the propellant reorientation process across a wide range of spacecraft, for a variety of missions, for the entire duration of a mission, and with a minimum of hardware design and qualification.

Hochstein, John I.; Patag, Alfredo E.; Korakianitis, T. P.; Chato, David J.

1992-01-01

242

Pulsed thrust propellant reorientation - Concept and modeling  

NASA Astrophysics Data System (ADS)

The use of pulsed thrust to optimize the propellant reorientation process is proposed. The ECLIPSE code is used to study the performance of pulsed reorientation in small-scale and full-scale propellant tanks. A dimensional analysis of the process is performed and the resulting dimensionless groups are used to present and correlate the computational predictions of reorientation performance. Based on the results obtained from this study, it is concluded that pulsed thrust reorientation seems to be a feasible technique for optimizing the propellant reorientation process across a wide range of spacecraft, for a variety of missions, for the entire duration of a mission, and with a minimum of hardware design and qualification.

Hochstein, John I.; Patag, Alfredo E.; Korakianitis, T. P.; Chato, David J.

1992-08-01

243

CFD Code Survey for Thrust Chamber Application  

NASA Technical Reports Server (NTRS)

In the quest fo find analytical reference codes, responses from a questionnaire are presented which portray the current computational fluid dynamics (CFD) program status and capability at various organizations, characterizing liquid rocket thrust chamber flow fields. Sample cases are identified to examine the ability, operational condition, and accuracy of the codes. To select the best suited programs for accelerated improvements, evaluation criteria are being proposed.

Gross, Klaus W.

1990-01-01

244

Low Carbon Propulsion Strategic Thrust Overview  

NASA Technical Reports Server (NTRS)

NASA is taking a leadership role with regard to developing new options for low-carbon propulsion. Work related to the characterization of alternative fuels is coordinated with our partners in government and industry, and NASA is close to concluding a TC in this area. Research on alternate propulsion concepts continues to grow and is an important aspect of the ARMD portfolio. Strong partnerships have been a key enabling factor for research on this strategic thrust.

Dryer, Jay

2014-01-01

245

Development of sputtered techniques for thrust chambers  

NASA Technical Reports Server (NTRS)

Techniques and materials were developed and evaluated for the fabrication and coating of advanced, long life, regeneratively cooled thrust chambers. Materials were analyzed as fillers for sputter application of OFHC copper as a closeout layer to channeled inner structures; of the materials evaluated, aluminum was found to provide the highest bond strength and to be the most desirable for chamber fabrication. The structures and properties were investigated of thick sputtered OFHC copper, 0.15 Zr-Cu, Al2O3,-Cu, and SiC-Cu. Layered structures of OFHC copper and 0.15 Zr-Cu were investigated as means of improving chamber inner wall fatigue life. The evaluation of sputtered Ti-5Al-2.5Sn, NASA IIb-11, aluminum and Al2O3-Al alloys as high strength chamber outer jackets was performed. Techniques for refurbishing degraded thrust chambers with OFHC copper and coating thrust chambers with protective ZrO2 and graded ZrO2-copper thermal barrier coatings were developed.

Mullaly, J. R.; Hecht, R. J.; Schmid, T. E.; Torrey, C. T.

1975-01-01

246

A guidance and navigation system for continuous low thrust vehicles. M.S. Thesis  

NASA Technical Reports Server (NTRS)

A midcourse guidance and navigation system for continuous low thrust vehicles is described. A set of orbit elements, known as the equinoctial elements, are selected as the state variables. The uncertainties are modelled statistically by random vector and stochastic processes. The motion of the vehicle and the measurements are described by nonlinear stochastic differential and difference equations respectively. A minimum time nominal trajectory is defined and the equation of motion and the measurement equation are linearized about this nominal trajectory. An exponential cost criterion is constructed and a linear feedback guidance law is derived to control the thrusting direction of the engine. Using this guidance law, the vehicle will fly in a trajectory neighboring the nominal trajectory. The extended Kalman filter is used for state estimation. Finally a short mission using this system is simulated. The results indicate that this system is very efficient for short missions.

Tse, C. J. C.

1973-01-01

247

Jet flow in steadily swimming adult squid.  

PubMed

Although various hydrodynamic models have been used in past analyses of squid jet propulsion, no previous investigations have definitively determined the fluid structure of the jets of steadily swimming squid. In addition, few accurate measurements of jet velocity and other jet parameters in squid have been reported. We used digital particle imaging velocimetry (DPIV) to visualize the jet flow of adult long-finned squid Loligo pealei (mantle length, L(m)=27.1+/-3.0 cm, mean +/-S.D.) swimming in a flume over a wide range of speeds (10.1-59.3 cm s(-1), i.e. 0.33-2.06 L(m) s(-1)). Qualitatively, squid jets were periodic, steady, and prolonged emissions of fluid that exhibited an elongated core of high speed flow. The development of a leading vortex ring common to jets emitted from pipes into still water often appeared to be diminished and delayed. We were able to mimic this effect in jets produced by a piston and pipe arrangement aligned with a uniform background flow. As in continuous jets, squid jets showed evidence of the growth of instability waves in the jet shear layer followed by the breakup of the jet into packets of vorticity of varying degrees of coherence. These ranged from apparent chains of short-lived vortex rings to turbulent plumes. There was some evidence of the complete roll-up of a handful of shorter jets into single vortex rings, but steady propulsion by individual vortex ring puffs was never observed. Quantitatively, the length of the jet structure in the visualized field of view, L(j), was observed to be 7.2-25.6 cm, and jet plug lengths, L, were estimated to be 4.4-49.4 cm using average jet velocity and jet period. These lengths and an average jet orifice diameter, D, of 0.8 cm were used to calculate the ratios L(j)/D and L/D, which ranged from 9.0 to 32.0 and 5.5 to 61.8, respectively. Jets emitted from pipes in the presence of a background flow suggested that the ratio between the background flow velocity and the jet velocity was more important than L/D to predict jet structure. Average jet velocities in steadily swimming squid ranged from 19.9 to 85.8 cm s(-1) (0.90-2.98 L(m) s(-1)) and were always greater in magnitude than swimming speed. Maximum instantaneous fluid speeds within squid jets ranged from 25.6 to 136.4 cm s(-1). Average jet thrust determined both from jet velocity and from three-dimensional approximations of momentum change in successive jet visualizations showed some differences and ranged from 0.009 to 0.045 N over the range of swimming speeds observed. The fraction by which the average jet velocity exceeded the swimming speed, or 'slip', decreased with increasing swimming speed, which reveals higher jet propulsive efficiency at higher swimming speeds. Jet angle, subtended from the horizontal, decreased from approximately 29 degrees to 7 degrees with increasing swimming speed. Jet frequency ranged from 0.6 to 1.3 Hz in the majority of swimming sequences, and the data suggest higher frequencies at the lowest and highest speeds. Jet velocity, angle, period and frequency exhibited increased variability at speeds between 0.6 and 1.4 L(m) s(-1). This suggests that at medium speeds squid enjoy an increased flexibility in the locomotive strategies they use to control their dynamic balance. PMID:15767313

Anderson, Erik J; Grosenbaugh, Mark A

2005-03-01

248

Vector Voyage!  

NSDL National Science Digital Library

In this activity, students will use vector analysis to understand the concept of dead reckoning. Students will use vectors to plot their course based on a time and speed. They will then correct the positions with vectors representing winds and currents.

Jeff White

2004-01-01

249

A flight investigation of the stability, control, and handling qualities of an augmented jet flap STOL airplane  

NASA Technical Reports Server (NTRS)

The stability, control, and handling qualities of an augmented jet flap STOL airplane are presented. The airplane is an extensively modified de Havilland Buffalo military transport. The modified airplane has two fan-jet engines which provide vectorable thrust and compressed air for the augmentor jet flap and Boundary-Layer Control (BLC). The augmentor and BLC air is cross ducted to minimize asymmetric moments produced when one engine is inoperative. The modifications incorporated in the airplane include a Stability Augmentation System (SAS), a powered elevator, and a powered lateral control system. The test gross weight of the airplane was between 165,000 and 209,000 N (37,000 and 47,000 lb). Stability, control, and handling qualities are presented for the airspeed range of 40 to 180 knots. The lateral-directional handling qualities are considered satisfactory for the normal operating range of 65 to 160 knots airspeed when the SAS is functioning. With the SAS inoperative, poor turn coordination and spiral instability are primary deficiencies contributing to marginal handling qualities in the landing approach. The powered elevator control system enhanced the controllability in pitch, particularly in the landing flare and stall recovery.

Vomaske, R. F.; Innis, R. C.; Swan, B. E.; Grossmith, S. W.

1978-01-01

250

The Zagros hinterland fold-and-thrust belt in-sequence thrusting, Iran  

NASA Astrophysics Data System (ADS)

The collision of the Iranian microcontinent with the Afro-Arabian continent resulted in the deformation of the Zagros orogenic belt. The foreland of this belt in the Persian Gulf and Arabian platform has been investigated for its petroleum and gas resource potentials, but the Zagros hinterland is poorly investigated and our knowledge about its deformation is much less than other parts of this orogen. Therefore, this work presents a new geological map, stratigraphic column and two detailed geological cross sections. This study indicates the presence of a hinterland fold-and-thrust belt on northeastern side of the Zagros orogenic core that consists of in-sequence thrusting and basement involvement in this important part of the Zagros hinterland. The in-sequence thrusting resulted in first- and second-order duplex systems, Mode I fault-bend folding, fault-propagation folding and asymmetric detachment folding which indicate close relationships between folding and thrusting. Study of fault-bend folds shows that layer-parallel simple shear has the same role in the southeastern and northwestern parts of the study area (?e = 23.4 ± 9.1°). A major lateral ramp in the basement beneath the Talaee plain with about one kilometer of vertical offset formed parallel to the SW movement direction and perpendicular to the major folding and thrusting.

Sarkarinejad, Khalil; Ghanbarian, Mohammad Ali

2014-05-01

251

Ouachita Mountain thrust front: An integrated approach to prospect analysis in thrust belts  

SciTech Connect

The thrust front of the Ouachita Mountains in western Arkansas is defined by the prominent asymmetric Washburn anticline. Previously interpreted as a complexly thrust-faulted anticline, the feature has been reinterpreted as a delta or triangle structure based on integration of surface mapping from thematic mapper (TM) data with subsurface interpretation of seismic and well-log cross sections. The northern limb of the Washburn anticline consists of a relatively unfaulted steeply north-dipping sheet above a major north-dipping backthrust. The southern limb consists of several steeply south-dipping thrust sheets that form a duplex zone in the center of the delta structure. Seismic and well-log interpretations suggested the presence of the imbrication in the core of the structure, but poor seismic resolution within the structure made interpretation of the backthrust and duplex geometry difficult. Surface mapping from TM imagery indicates the presence of the backthrust and the extent and geometry of the delta structure. Thrust sheets and horses also crop out, and their geometry is a guide to interpretation of subsurface data sets. The new model of the Ouachita thrust front as a delta structure has aided in subsurface data analysis and has resulted in a better understanding of trap geometry and distribution. This study also demonstrates the application of detailed surface mapping from satellite remote-sensing data to prospect-scale analysis.

Dodge, R.L. (Hunt Oil Co., Dallas, TX (USA)); Keeling, M.A. (Exxon Co., U.S.A., Houston, TX (USA)); Cassiani, D. (Exxon Yemen Inc., Houston, TX (USA))

1990-05-01

252

Small-scale noise tests of a slot nozzle with V-gutter target thrust reverser  

NASA Technical Reports Server (NTRS)

The noise generated by a 2.26- by 11.43-cm slot nozzle with a V-gutter reverser, as well as some aerodynamic data on flow, thrust-reversal efficiency, and nozzle jet velocity decay were studied. The experimental data are scaled up to sizes suitable for reversing the wing flow of a 45/400-kg augmentor-wing-type STOL airplane, yielding perceived noise levels well above the 95-PNdb design goal on the 152-m sideline. The reverser, in addition to being noisier than the nozzle alone, also had a more uniform directional distribution and more high frequency noise. The maximum overall sound pressure level and the effective sound power level both varied with the sixth power of nozzle jet velocity. Preliminary experiments indicated possible sideline noise reduction by shielding.

Stone, J. R.; Gutierrez, O. A.

1973-01-01

253

Paleostress analysis of the Osning Thrust, Germany  

NASA Astrophysics Data System (ADS)

The Osning Thrust is a 100 km-scale NW-SE fault separating the Lower Saxony Basin to the NE from the Münsterland Basin to the SE. The fault has accommodated a polyphase deformation that started at least when it acted as one of the normal border faults of the Jurassic Lower Saxony Basin. Tectonic inversion of the basin in Late Cretaceous-Early Paleocene times led to the development of the SE-vergent Osning Thrust and to folding of rocks. A paleostress analysis was carried out in order to decipher the polyphase kinematics of the Osning Thrust. The fault slip data were collected in the folded Albian to Turonian stratigraphic units of the Münsterland basin, in the SE vicinity of a 20 km-long steep segment of the Osning Thrust. Fault slip data in sufficient amount to perform paleostress inversion were collected in 10 sites among 23 visited outcrops. Abundant minor faults trend sub-parallel to the NW-SE steep segment of the Osning Thrust but, surprisingly, they are dextral (and not reverse) in type. Another major set of E-W striking minor faults is remarkable. It corresponds to conjugate systems of either reverse or normal faults and to oblique- to strike-slip faults in a less extent. The paleostress tensors reveal a ca. N-S compression recorded in 5 locations under which the NW-SE steep faults were dextral and the E-W striking S- and N- dipping faults were reverse. Six stress tensors fit with a ca. N-S extension. They are calculated from E-W striking S- and N- dipping normal to oblique normal faults. The same N-S trend of minimum stress axis is also recorded with NNE-SSW dextral and E-W sinistral faults. We propose that along the studied segment of the Osning Thrust a N-S compressional stress field led to the inversion of the Lower Saxony Basin and that slip along the Osning Thrust was oblique reverse. At two locations, the N-S compressive stress states affected the rock prior to tilting of the beds (herein, due to folding) and at one site, the normal faults of the N-S extension clearly cut across reverse faults of the N-S compression. These two observations allow to propose a chronology between the reconstructed stress fields. While the N-S compression is presumably linked to the Late Cretaceous-Early Palaeocene inversion of the Lower Saxony Basin, the successive E-W extension is not constrained in age. However, it is known that tensional stresses have largely affected the west European platform in Oligocene times and this N-S extension revealed by the present study might be related to this tectonic event.

Saintot, Aline; Kozakovski, Anna; Pascal, Christophe

2013-04-01

254

A computational investigation of impulsive and pulsed starting annular jets  

NASA Astrophysics Data System (ADS)

A computational study is carried out on low Reynolds number impulsive and pulsating annular jets. This work is inspired by the biological flow of marine life that uses jet propulsion for self maneuver. Marine life such as squids and jellyfish propel themselves by discharging a water jet followed by a refilling phase. The discharging portion is a starting jet, i.e. the releasing of a moving fluid into a quiescent fluid, while the refilling phase can be viewed as an inflow jet. The combined jets will be called fully oscillating jets. Although fully oscillating jets have been indirectly examined experimentally, they have never been studied computationally. This dissertation is divided into three investigations that examine the starting jet, inflow jet, and fully oscillating jet based on the resultant force (i.e. either thrust or suction force) at the annulus exit plane, jet efficiency, and vortex dynamics. Furthermore, each of the following three performance criterion is examined under various velocity imposed boundaries (i.e. impulsive, unit pulsed, and sinusoidal pulsed jets), ambient pressure, and blocking ratios. An axisymmetric, incompressible and unsteady Navier Stokes numerical model was used to implement the analysis. The model was validated against theoretical and experimental results, where both result types bounded the computational results of this endeavor. In addition, numerical verification was carried out on each of the three investigations ensuring grid and time independent results. Several substantial outcomes were drawn from the results of the three investigations. The numerical results confirmed previously published experimental data regarding the universal dimensionless time scale (i.e. vortex formation number) of optimal vortex ring development triggered by starting jets. Moreover, the computational results showed evidence that the vortex formation number was not affected by ambient pressure nor blocking ratio. The computational results also confirmed earlier experimental findings that pulsed jet inflows trigger a standing vortex ring. Furthermore, the current study showed that impulsive jet inflows do not trigger vortex ring formation. In addition, unlike the expected net thrust of zero due to mass flux, fully oscillating jets showed evidence of thrust augmentation due to the enhanced entrainment caused by the vortex formation.

Abdel-Raouf, Emad Mohamed Refaat

2011-12-01

255

Extended performance solar electric propulsion thrust system study. Volume 2: Baseline thrust system  

NASA Technical Reports Server (NTRS)

Several thrust system design concepts were evaluated and compared using the specifications of the most advanced 30- cm engineering model thruster as the technology base. Emphasis was placed on relatively high-power missions (60 to 100 kW) such as a Halley's comet rendezvous. The extensions in thruster performance required for the Halley's comet mission were defined and alternative thrust system concepts were designed in sufficient detail for comparing mass, efficiency, reliability, structure, and thermal characteristics. Confirmation testing and analysis of thruster and power-processing components were performed, and the feasibility of satisfying extended performance requirements was verified. A baseline design was selected from the alternatives considered, and the design analysis and documentation were refined. The baseline thrust system design features modular construction, conventional power processing, and a concentractor solar array concept and is designed to interface with the space shuttle.

Poeschel, R. L.; Hawthorne, E. I.

1977-01-01

256

Twin jet shielding. [for aircraft noise reduction  

NASA Technical Reports Server (NTRS)

For an over-the-wing/under-the-wing engine configuration on an airplane, the noise produced by the upper jet flow is partially reflected by the lower jet. An analysis has been performed which can be used to predict the distribution of perceived noise levels along the ground plane at take-off for an airplane which is designed to take advantage of the over/under shielding concept. Typical contours of PNL, the shielding benefit in the shadow zone, and the EPNL values at 3.5 nautical miles from brake release as well as EPNL values at sideline at 0.35 nautical miles have been calculated. This has been done for a range of flow parameters characteristic of engines producing inverted velocity profile jets suitable for use in a supersonic cruise vehicle. Reductions up to 6.0 EPNdB in community noise levels can be realized when the over engines are operated at higher thrust and the lower engines simultaneously operated with reduced thrust keeping the total thrust constant.

Parthasarathy, S. P.; Cuffel, R. F.; Massier, P. F.

1979-01-01

257

NLO Jet Physics with BlackHat  

SciTech Connect

We present several results obtained using the BLACKHAT next-to-leading order QCD program library, in conjunction with SHERPA. In particular, we present distributions for vector boson plus 1,2,3-jet production at the Tevatron and at the asymptotic running energy of the Large Hadron Collider, including new Z + 3-jet distributions. The Z + 2-jet predictions for the second-jet P{sub T} distribution are compared to CDF data. We present the jet-emission probability at NLO in W + 2-jet events at the LHC, where the tagging jets are taken to be the ones furthest apart in pseudorapidity. We analyze further the large left-handed W{sup {+-}} polarization, identified in our previous study, for W bosons produced at high P{sub T} at the LHC.

Berger, C.F.; /MIT, LNS; Bern, Z.; /UCLA; Dixon, L.J.; /SLAC; Cordero, F.Febres; /Simon Bolivar U.; Forde, D.; /CERN /NIKHEF, Amsterdam; Gleisberg, T.; /SLAC; Ita, H.; /UCLA; Kosower, D.A.; /DAPNIA, Saclay; Maitre, D.; /Durham U.

2010-02-15

258

Two-phase jet loads. Fiscal year 1979 annual report  

Microsoft Academic Search

The consequences of a pipe break must be considered in detail in the design of a nuclear power plant system. Pipe restraints must be installed to prevent large displacements resulting from thrust forces, and jet deflectors must be engineered to preclude additional effluent damage on the system. Over-design of the system must be avoided due to safety and economic considerations.

1980-01-01

259

Control of Jet Noise Through Mixing Enhancement  

NASA Technical Reports Server (NTRS)

The idea of using mixing enhancement to reduce jet noise is not new. Lobed mixers have been around since shortly after jet noise became a problem. However, these designs were often a post-design fix that rarely was worth its weight and thrust loss from a system perspective. Recent advances in CFD and some inspired concepts involving chevrons have shown how mixing enhancement can be successfully employed in noise reduction by subtle manipulation of the nozzle geometry. At NASA Glenn Research Center, this recent success has provided an opportunity to explore our paradigms of jet noise understanding, prediction, and reduction. Recent advances in turbulence measurement technology for hot jets have also greatly aided our ability to explore the cause and effect relationships of nozzle geometry, plume turbulence, and acoustic far field. By studying the flow and sound fields of jets with various degrees of mixing enhancement and subsequent noise manipulation, we are able to explore our intuition regarding how jets make noise, test our prediction codes, and pursue advanced noise reduction concepts. The paper will cover some of the existing paradigms of jet noise as they relate to mixing enhancement for jet noise reduction, and present experimental and analytical observations that support these paradigms.

Bridges, James; Wernet, Mark; Brown, Cliff

2003-01-01

260

High-power, null-type, inverted pendulum thrust stand.  

PubMed

This article presents the theory and operation of a null-type, inverted pendulum thrust stand. The thrust stand design supports thrusters having a total mass up to 250 kg and measures thrust over a range of 1 mN to 5 N. The design uses a conventional inverted pendulum to increase sensitivity, coupled with a null-type feature to eliminate thrust alignment error due to deflection of thrust. The thrust stand position serves as the input to the null-circuit feedback control system and the output is the current to an electromagnetic actuator. Mechanical oscillations are actively damped with an electromagnetic damper. A closed-loop inclination system levels the stand while an active cooling system minimizes thermal effects. The thrust stand incorporates an in situ calibration rig. The thrust of a 3.4 kW Hall thruster is measured for thrust levels up to 230 mN. The uncertainty of the thrust measurements in this experiment is +/-0.6%, determined by examination of the hysteresis, drift of the zero offset and calibration slope variation. PMID:19485530

Xu, Kunning G; Walker, Mitchell L R

2009-05-01

261

Stellar jets  

E-print Network

With a goal of understanding the conditions under which jets might be produced in novae and related objects, I consider the conditions under which jets are produced from other classes of accreting compact objects. I give an overview of accretion disk spectral states, including a discussion of in which states these jets are seen. I highlight the differences between neutron stars and black holes, which may help give us insights about when and how the presence of a solid surface may help or inhibit jet production.

Thomas J. Maccarone

2008-05-23

262

Design and test of a magnetic thrust bearing  

NASA Technical Reports Server (NTRS)

A magnetic thrust bearing can be employed to take thrust loads in rotating machinery. The design and construction of a prototype magnetic thrust bearing for a high load per weight application is described. The theory for the bearing is developed. Fixtures were designed and the bearing was tested for load capacity using a universal testing machine. Various shims were employed to have known gap thicknesses. A comparison of the theory and measured results is presented.

Allaire, P. E.; Mikula, A.; Banerjee, B.; Lewis, D. W.; Imlach, J.

1993-01-01

263

Space shuttle orbit maneuvering engine reusable thrust chamber program  

NASA Technical Reports Server (NTRS)

Tests were conducted on the regenerative cooled thrust chamber of the space shuttle orbit maneuvering engine. The conditions for the tests and the durations obtained are presented. The tests demonstrated thrust chamber operation over the nominal ranges of chamber pressure mixture ratio. Variations in auxiliary film coolant flowrate were also demonstrated. High pressure tests were conducted to demonstrate the thrust chamber operation at conditions approaching the design chamber pressure for the derivative space tug application.

Pauckert, R. P.; Yost, M. C.; Tobin, R. D.

1973-01-01

264

Bulletin of the Seismological Society of America, 91, 5, pp. 986994, October 2001 1999 Chi-Chi Earthquake: A Case Study on the Role of Thrust-Ramp  

E-print Network

-Chi Earthquake: A Case Study on the Role of Thrust-Ramp Structures for Generating Earthquakes Wen-Shan Chen, Bor recent arc-continent collision. Measurement of slip vectors along the earthquake rupture indicates, riverbanks, fences, or dams where a fault plane could be defined in the field. However, disruptions within

Chen, Wen-Shan

265

Rocket thrust chamber thermal barrier coatings  

NASA Technical Reports Server (NTRS)

A research program was conducted to generate data and develop analytical techniques to predict the performance and reliability of ceramic thermal barrier coatings in high heat flux environments. A finite element model was used to analyze the thermomechanical behavior of coating systems in rocket thrust chambers. Candidate coating systems (using a copper substrate, NiCrAlY bond coat and ZrO2.8Y2O3 ceramic overcoat) were selected for detailed study based on photomicrographic evaluations of experimental test specimens. The effects of plasma spray application parameters on the material properties of these coatings were measured and the effects on coating performance evaluated using the finite element model. Coating design curves which define acceptable operating envelopes for seleted coating systems were constructed based on temperature and strain limitations. Spray gun power levels was found to have the most significant effect on coating structure. Three coating systems were selected for study using different power levels. Thermal conductivity, strain tolerance, density, and residual stress were measured for these coatings. Analyses indicated that extremely thin coatings ( 0.02 mm) are required to accommodate the high heat flux of a rocket thrust chamber and ensure structural integrity.

Batakis, A. P.; Vogan, J. W.

1985-01-01

266

Experimental Results of Schlicher's Thrusting Antenna  

NASA Technical Reports Server (NTRS)

Experiments were conducted to test the claims by Rex L. Schlicher, et al., (Patent 5,142,86 1) that a certain antenna geometry produces thrust greatly exceeding radiation reaction, when driven by repetitive, fast rise, and relatively slower decay current pulses. In order to test this hypothesis, the antenna was suspended by strings as a 3 in pendulum. Current pulses were fed to the antenna along the suspension path by a very flexible coaxial line constructed from loudspeaker cable and copper braid sheath. When driving the antenna via this cabling, our pulser was capable of sustaining 1200 A pulses at a rate of 30 per second up to a minute. In this way, bursts of pulses could be delivered in synch with the pendulum period in order to build up any motion. However, when using a laser beam passing through a lens attached to the antenna to amplify linear displacement by a factor of at least 25, no correlated motion of the beam spot could be detected on a distant wall. We conclude, in agreement with the momentum theorem of classical electromagnetic theory, that any thrust produced is far below practically useful levels. Hence, within classical electrodynamics, there is little hope of detecting any low level motion that cannot be explained by interactions with surrounding structural steel and the Earth's magnetic field.

Fralick, Gustave C.; Niedra, Janis M.

2001-01-01

267

OMV/VTE variable thrust engine analysis  

NASA Technical Reports Server (NTRS)

The objective of the present work is to develop a predictive CFD based analytical tool for the variable thrust engine (VTE) in the orbital maneuvering vehicle (OMV). This objective is being accomplished within the framework of the Los Alamos KIVA computer code for chemically reactive flows with sprays. For the OMV application, the main structure of KIVA is to be retained while reformulating many of the phenomenological submodels, enhancing some of the numerics, and adding more features. The analytical model consists of the general conservation equations for two phase reactive flows and of submodels for turbulence, chemical reactions, and bipropellant sprays. Tailoring this model to the OMV engine brings about the added complexities of combustion and flow processes that occur in a liquid hypergolic propellant rocket chamber. This report exposes the foundation upon which the analytical tool is being constructed and developed. Results from a cursory computational exercise involving the simulation of the flow and combustion processes in a hypothetical N2H4/N2O4 rocket engine thrust chamber is presented and discussed.

Larosillere, Louis; Litchford, Ron; Jeng, San-Mou

1989-01-01

268

Emergency Control Aircraft System Using Thrust Modulation  

NASA Technical Reports Server (NTRS)

A digital longitudinal Aircraft Propulsion Control (APC system of a multiengine aircraft is provided by engine thrust modulation in response to comparing an input flightpath angle signal (gamma)c from a pilot thumbwheel. or an ILS system with a sensed flightpath angle y to produce an error signal (gamma)e that is then integrated (with reasonable limits) to generate a drift correction signal to be added to the error signal (gamma)e after first subtracting a lowpass filtered velocity signal Vel(sub f) for phugoid damping. The output error signal is multiplied by a constant to produce an aircraft thrust control signal ATC of suitable amplitude to drive a throttle servo for all engines. each of which includes its own full-authority digital engine control (FADEC) computer. An alternative APC system omits sensed flightpath angle feedback and instead controls the flightpath angle by feedback of the lowpass filtered velocity signal Vel(sub f) which also inherently provides phugoid damping. The feature of drift compensation is retained.

Burken, John J. (Inventor); Burcham, Frank W., Jr. (Inventor)

2000-01-01

269

Some effects of cyclic induced deformation in rocket thrust chambers  

NASA Technical Reports Server (NTRS)

A test program to investigate the deformation process observed in the hot gas wall of rocket thrust chambers was conducted using three different liner materials. Five thrust chambers were cycled to failure using hydrogen and oxygen as propellants at a chamber pressure of 4.14 MN/sq m. The deformation was observed nondestructively at midlife points and destructively after failure occurred. The cyclic life results are presented with an accompanying discussion about the types of failure encountered. Data indicating the deformation of the thrust chamber liner as cycles are accumulated are presented for each of the test thrust chambers.

Hannum, N. P.; Quentmeyer, R. J.; Kasper, H. J.

1979-01-01

270

Unsteady thrust measurement techniques for pulse detonation engines  

NASA Astrophysics Data System (ADS)

Thrust is a critical performance parameter and its correct determination is necessary to characterize an engine. Many conventional thrust measurement techniques prevail. However, further developments are required for correct measurement of thrust in the case of a pulse detonation engine (PDE), since the entire thrust generation process is intermittent. The significant effect of system dynamics in the form of inertial forces, stress wave propagation and reflections initiated in the structure due to detonations and pulse-to-pulse interaction in a fast operating PDE further complicate the thrust measurement process. These complications call for a further, detailed study of the unsteady thrust characteristics. A general approach was first developed to recover actual thrust from the measured thrust generated by the PDE. The developed approach consisted of two steps. The first step incorporated a deconvolution procedure using a pre-established system transfer function and measured input to reconstruct the output yielding the deconvolved thrust. The second step accounted for inertial forces through an acceleration compensation procedure. These two steps allowed the actual thrust to be determined. A small scale PDE operating at 10 and 20 Hz with varied filling fractions and mixture equivalence ratios was used for the experimental application of the general approach. The analytical study of gas dynamics in the PDE while in operation and the measured pressure histories at the exit of the engine allowed the generated thrust during a cycle to be determined semi-empirically. The thrust values determined semi-empirically were compared against the experimental results. A dynamical model of the PDE was created for the study of the unsteady thrust characteristics using finite element analysis. The results from finite element analysis were compared against semi-empirical and experimental results. In addition, finite element analysis also facilitated to numerically determine the unsteady thrust generated by the PDE at higher operating frequencies of 50 and 100 Hz. The actual thrust estimated experimentally, semi-empirically and numerically were expressed in the form of specific impulse for comparison. The results obtained via semi-empirical method and finite element analysis were found to be in good agreement with each other. However, the results obtained experimentally were slightly lower than the other two. Finally, the results obtained in this research work were also compared against the findings reported in literature. The comparison gave satisfying results. The developed general approach used to recover actual thrust generated by a PDE was also used to recover actual aerodynamic drag experienced by a blunt nose cone model in a nominal Mach 8-9 flow. The limited validation against modified Newtonian theory was provided as the results obtained after applying the developed approach matched the predicted values.

Joshi, Dibesh Dhoj

271

Kinematic modeling of folding above listric propagating thrusts  

NASA Astrophysics Data System (ADS)

We describe a kinematic approach to simulate folds above listric propagating thrusts. The model is based on a pre-defined circular thrust geometry with a maximum central angle beyond which the thrust is planar, inclined shear above the circular thrust, and trishear in front of the thrust. Provided the trajectory of thrust propagation is established, the model can be run forward and backwards. We use this last feature to implement a global simulated annealing, inverse modeling strategy. This inverse modeling strategy is applied to synthetic folds as well as two real examples in offshore Venezuela and the Niger Delta toe-thrust system. These three examples illustrate the benefits of the algorithm, particularly in predicting the possible range of models that can fit the structures. Thrust geometry, depth to detachment level, and backlimb geometry have high impact in model parameters such as backlimb shear angle and fault slip; while forelimb geometry is critical to constrain parameters such as fault propagation to fault slip ratio and trishear angle. Steep to overturned beds in forelimb areas are often not imaged by seismic, so in the absence of additional well data, considering all possible thrust-fold geometries is critical for the modeling and whatever prediction (e.g. hydrocarbon trap integrity) is made from it.

Cardozo, Nestor; Brandenburg, J. P.

2014-03-01

272

Fault interaction along the Central Andean thrust front: The Las Peñas thrust, Cerro Salinas thrust and the Montecito Anticline  

NASA Astrophysics Data System (ADS)

The region in west-central Argentina between the thin-skinned Precordillera and the thick-skinned Sierras Pampeanas structural domain is among the most active zones of thrust tectonics in the world. We quantify the rates of deformation on the east-vergent Las Peñas thrust (LPT), and the west-vergent Cerro Salinas thrust (CST). The Montecito anticline (MA) is located at their intersection. We mapped three key locations, collected stratigraphic logs from the MA, dated three ashes using U-Pb in zircon and dated 10 terraces using cosmogenic Be-10 depth profiles. Five terrace levels are present where the Rio Las Peñas crosses the LPT, up to 45 m above the modern river. Cosmogenic dating of the uppermost terrace (T1) yields and age of 123.8 +26.5/-12.3 ka. A reconstruction of this surface using a blind thrust rupture scenario indicates 73 +/- 7 m horizontal shortening and 34 +/- 3 m vertical displacement. Shortening across the structure is therefore 0.59 +0.10/-0.13 mm/yr with a vertical uplift rate of 0.27 +0.05/-0.06 mm/a. Previous work indicates higher rates to the south on the order of 2 mm/yr (Schmidt et al., 2011). Lower terraces give ages of 38.0 +11/-6.2 ka (T2) and 1.5 +5.0/-0.6 ka (T4). Three terrace levels are preserved near the center of the CST. The middle surface (T2) is folded across the axis of the structure and yields an age of 112.5 +33/-14.4 ka. Given 22.9 m surface uplift, this indicates a vertical uplift rate of 0.20 +0.05/-0.06 mm/yr, similar to the rate on the LPT. The upper terrace (T1) yields a younger age (97.1 +29.8/-12.4 ka); the T1 and T2 ages overlap within uncertainty, indicating rapid river incision at the time of their formation. An intercalated ash within the Neogene strata gives an age of 16.2 +/- 0.2. Previous work indicates long-term shortening rates of 0.8 mm/yr (Verges et al., 2007) and that the CST initiated after 8.5 Ma. The lowermost unit exposed in the MA is the Los Pozos Fm., with no indication of syn-depositional deformation. An intercalated ash from the top of this formation yields an age of 5.76 +/- 0.09 Ma. Internal unconformities are present within the overlying transitional unit and the Mogotes Fm., indicating deformation post-dates 5.8 Ma in the MA. An ash within the Mogotes Fm. is 1.52 +/- 0.06 Ma. Slip is modeled as 3.5 km reverse slip across an east-dipping dislocation with a 45 degree dip. This suggests horizontal shortening and vertical uplift of 0.42 mm/yr since the onset of deformation. Uplifted terraces near the center of the MA are 4.7 +0.8/-0.3 ka (T2) and 1.9 +3.4/-1.9 ka (T3), 6 and 4.6 m above the modern river, respectively. This suggests recent vertical uplift or incision rates of 1.3-2.4 mm/yr. These data suggest that deformation in the MA is comparable to that at the LPT and CST. Deformation in the MA could be accelerating, but alternatively, river incision could be accelerating due to climate change.

Schoenbohm, L. M.; Costa, C. H.; Brooks, B. A.; Bohon, W.; Gardini, C.; Cisneros, H.

2013-12-01

273

Thrust Removal Scheme for the FAST-MAC Circulation Control Model Tested in the National Transonic Facility  

NASA Technical Reports Server (NTRS)

A second wind tunnel test of the FAST-MAC circulation control semi-span model was recently completed in the National Transonic Facility at the NASA Langley Research Center. The model allowed independent control of four circulation control plenums producing a high momentum jet from a blowing slot near the wing trailing edge that was directed over a 15% chord simple-hinged flap. The model was configured for transonic testing of the cruise configuration with 0deg flap deflection to determine the potential for drag reduction with the circulation control blowing. Encouraging results from analysis of wing surface pressures suggested that the circulation control blowing was effective in reducing the transonic drag on the configuration, however this could not be quantified until the thrust generated by the blowing slot was correctly removed from the force and moment balance data. This paper will present the thrust removal methodology used for the FAST-MAC circulation control model and describe the experimental measurements and techniques used to develop the methodology. A discussion on the impact to the force and moment data as a result of removing the thrust from the blowing slot will also be presented for the cruise configuration, where at some Mach and Reynolds number conditions, the thrust-removed corrected data showed that a drag reduction was realized as a consequence of the blowing.

Chan, David T.; Milholen, William E., II; Jones, Gregory S.; Goodliff, Scott L.

2014-01-01

274

Synthetic jets  

Microsoft Academic Search

The evolution of a synthetic (zero-net mass flux) jet and the flow mechanisms of its interaction with a cross flow are reviewed. An isolated synthetic jet is produced by the interactions of a train of vortices that are typically formed by alternating momentary ejection and suction of fluid across an orifice such that the net mass flux is zero. A

Ari Glezer; Michael Amitay

2002-01-01

275

Erosional history and possible passive uplift of Paris-Willard Thrust allochthon, Wyoming-Idaho-Utah Thrust Belt  

SciTech Connect

Stratigraphic distribution of clast lithologies in Sevier foreland basin synorogenic conglomerates in the southwestern Wyoming-southeastern Idaho-northeastern Utah thrust belt provides evidence of the erosional history of the Paris-Willard thrust allochthon. Conglomerates of the Upper Jurassic-Lower Cretaceous Gannett Group were deposited in response to initial movement along the Paris-Willard thrust system and are comprised of cobbles and pebbles of Ordovician through Jurassic strata, with upper Paleozoic and lower Mesozoic clasts most common. Thus, by conclusion of initial Paris-Willard thrust movement, the allochthon had been affected by widespread erosion of lower Paleozoic through lower Mesozoic strata. Evidence for subsequent erosion to deeper stratigraphic levels is contained in the basal Hams Fork Conglomerate Member of the Upper Cretaceous-Paleocene Evanston Formation. This unit contains abundant Precambrian quartzite cobbles, which must have been derived from the Paris-Willard allochthon, the only thrust sheet that contains Precambrian quartzite units. Genesis of the Hams Fork Conglomerate has been related to latest Cretaceous major movement along the Absaroka thrust. Thus, either the Paris-Willard thrust was fortuitously reactivated at the same time as major Absaroka thrust movement or uplift associated with movement along the Absaroka thrust resulted in coeval uplift of the Paris-Willard allochthon.

Schmitt, J.G.

1985-05-01

276

Thrust Enhancement in Hypervelocity Nozzles by Chemical Catalysis  

NASA Technical Reports Server (NTRS)

In the hypersonic flight regime, the air-breathing supersonic combustion ramjet (scramjet) has been shown to be a viable propulsion system. The current designs of scramjet engines provide performance benefits only up to a Mach number of 14. Performance losses increase rapidly as the Mach number increases. To extend the applicability of scram'jets beyond Mach 14, research is being conducted in the area of inlet and wave drag reduction, skin-friction and heat-transfer reduction, nozzle loss minimization, low-loss mixing, and combustion enhancement. For high Mach number applications, hydrogen is the obvious fuel choice because of its high energy content per unit mass in comparison with conventional fuels. These flight conditions require engines to operate at supersonic internal velocities, high combustor temperatures, and low static pressures. The high static temperature condition enhances the production of radicals such as H and OH, and the low-pressure condition slows the reaction rates, particularly the recombination reactions. High-temperature and low-pressure constraints, in combination with a small residence time, result in a radical-rich exhaust gas mixture exiting the combustor. At high Mach number conditions (due to low residence time), H and OH do not have enough time to recombine ; thus, a significant amount of energy is lost as these high-energy free radical are exhausted. The objective of the present study is to conduct a flowfield analysis for a typical nozzle geometry for NASP-type vehicle to assess for thrust enhancement in hypervelocity nozzles by substituting small amount of phosphine for hydrogen.

Singh, D. J.; Carpenter, Mark H.; Drummond, J. P.

1997-01-01

277

Resummation properties of jet vetoes at the LHC  

NASA Astrophysics Data System (ADS)

Jet vetoes play an important role at the LHC in the search for the Higgs and ultimately in precise measurements of its properties. Many Higgs analyses divide the cross section into exclusive jet bins to maximize the sensitivity in different production and decay channels. For a given jet category, the veto on additional jets introduces sensitivity to soft and collinear emissions, which causes logarithms in the perturbative expansion that need to be resummed to obtain precise predictions. We study the higher-order resummation properties of several conceptually distinct kinematic variables that can be used to veto jets in hadronic collisions. We consider two inclusive variables, the scalar sum over pT and beam thrust, and two corresponding exclusive variables based on jet algorithms, namely, the largest pT and largest beam thrust of a jet. The inclusive variables can, in principle, be resummed to higher orders. We show that for the jet-based variables, there are dual effects due to clustering in the jet algorithm for both large and small jet radius R that make a complete resummation at or beyond next-to-leading logarithmic order challenging. For R˜1, the clustering of soft and collinear emissions gives O(1) contributions starting at next-to-next-to-leading logarithm that are not reproduced by an all-orders soft-collinear factorization formula and therefore are not automatically resummed by it. For R?1, clustering induces logarithms of R that contribute at next-to-leading logarithm in the exponent of the cross section, which cannot be resummed with currently available methods. We explicitly compute the leading jet clustering effects at O(?s2) and comment on their numerical size.

Tackmann, Frank J.; Walsh, Jonathan R.; Zuberi, Saba

2012-09-01

278

Composite Octet Searches with Jet Substructure  

SciTech Connect

Many new physics models with strongly interacting sectors predict a mass hierarchy between the lightest vector meson and the lightest pseudoscalar mesons. We examine the power of jet substructure tools to extend the 7 TeV LHC sensitivity to these new states for the case of QCD octet mesons, considering both two gluon and two b-jet decay modes for the pseudoscalar mesons. We develop both a simple dijet search using only the jet mass and a more sophisticated jet substructure analysis, both of which can discover the composite octets in a dijet-like signature. The reach depends on the mass hierarchy between the vector and pseudoscalar mesons. We find that for the pseudoscalar-to-vector meson mass ratio below approximately 0.2 the simple jet mass analysis provides the best discovery limit; for a ratio between 0.2 and the QCD-like value of 0.3, the sophisticated jet substructure analysis has the best discovery potential; for a ratio above approximately 0.3, the standard four-jet analysis is more suitable.

Bai, Yang; /SLAC; Shelton, Jessie; /Yale U.

2012-02-14

279

Vector processing  

SciTech Connect

An apparatus is described for adapting a scalar data processor having a cache memory connected between main memory and a central processing unit, for efficient vector processing including: means for defining separate scalar and vector data areas in the cache memory, vector mode selection means for selectively enabling access to either the vector or scalar data areas of the cache memory, cache memory addressing means including separate vector and scalar addressing means responsive to the vector mode selection means and the central processing unit for accessing either the vector or scalar data areas of the cache memory, wherein the central processing unit includes: a pair of operand registers, and a result register, coupling means for providing a data path from the operand registers to an ALU and a further data path from an ALU to the result register, second coupling means for providing a data path from the cache memory to one of the operand registers and to the result register; an output buffer; third coupling means providing a data path from either of the operand registers to the second coupling means and to the output buffer; fourth coupling means providing a data path from the second coupling means or the output buffer to the cache memory; and fifth coupling means providing a data path from the result register to either of the operand registers.

Drimak, E.G.

1986-06-10

280

Thrust Production in a Mechanical Swimming Lamprey  

NASA Astrophysics Data System (ADS)

To develop a comprehensive model of lamprey locomotion, we use a robotic lamprey as a means of investigating the surface pressure and wake structure during swimming. A programmable microcomputer actuates 11 servomotors that produce a traveling wave along the length of the lamprey body. The waveform is based on the motion of the American eel (Anguilla rostrata), as described by Tytell and Lauder (2004) and kinematic studies of living lamprey. The amplitude of the phase-averaged surface pressure distribution along the centerline of the robot increases toward the tail, which is consistent with previous momentum balance experiments indicating that thrust is produced mainly at the tail. The phase relationship between the pressure signal and the vortex shedding from the tail is also examined. The project is supported by NIH CNRS Grant 1R01NS054271.

Leftwich, Megan; Smits, Alexander

2008-11-01

281

Initiation system for low thrust motor igniter  

NASA Technical Reports Server (NTRS)

A test program was carried out to demonstrate an igniter motor initiation system utilizing the bimetallic material Pyrofuze for a solid propellant rocket with controlled low rate of thrust buildup. The program consisted of a series of vacuum ignition tests using a slab burning window motor that simulated the principal initial ballistic parameters of the full scale igniter motor. A Pyrofuze/pyrotechnic igniter system was demonstrated that uses a relatively low electrical current level for initiation and that eliminates the necessity of a pyrotechnic squib, with its accompanying accidental firing hazards and the typical basket of pyrotechnic pellets. The Pyrofuze ignition system does require an initial constraining of the igniter motor nozzle flow, and at the low initiating electrical current level the ignition delay time of this system was found to be quite sensitive to factors affecting local heat generation or loss rates.

Strand, L. D.; Davis, D. P.; Shafer, J. I.

1972-01-01

282

Electronics Engineering Department Thrust Area report FY'84  

SciTech Connect

This report describes the work of the Electronics Engineering Department Thrust Areas for FY'84: diagnostics and microelectronic engineering; signal and control engineering; microwave and pulsed power engineering; computer-aided engineering; engineering modeling and simulation; and systems engineering. For each Thrust Area, an overview and a description of the goals and achievements of each project is provided.

Minichino, C.; Phelps, P.L. (eds.)

1984-01-01

283

3-D surface analysis of worn spherical roller thrust bearings  

Microsoft Academic Search

Wear of boundary lubricated spherical roller thrust bearings has been characterised with 3-D surface measurements and analysis. Due to the curved contact surface in a spherical roller thrust bearing, the rollers will undergo sliding in the contact. For an unskewed roller there will be two points along each contact where the sliding velocity is zero. At all other points along

Ulf Olofsson; Stefan Björklund

1998-01-01

284

Characterisation of wear in boundary lubricated spherical roller thrust bearings  

Microsoft Academic Search

Wear of boundary lubricated spherical roller thrust bearings has been characterised qualitatively as well as quantitatively with 3-d surface measurements and 2-d form measurements respectively. Due to the curved contact surface in a spherical roller thrust bearing, the rollers will undergo sliding in the contact. For an unskewed roller there will be two points along each contact where the sliding

Ulf Olofsson

1997-01-01

285

Nanobalance: An automated interferometric balance for micro-thrust measurement  

E-print Network

Nanobalance: An automated interferometric balance for micro-thrust measurement Enrico Canuto micro-thrusters in the range 0­1 mN with submicronewton accuracy. Low-noise micro-thrusters pendulums suspended at a constant distance, one of which carrying the micro-thruster under test. Any thrust

Canuto, Enrico

286

Heat pipe technology for advanced rocket thrust chambers  

NASA Technical Reports Server (NTRS)

The application of heat pipe technology to the design of rocket engine thrust chambers is discussed. Subjects presented are: (1) evaporator wick development, (2) specific heat pipe designs and test results, (3) injector design, fabrication, and cold flow testing, and (4) preliminary thrust chamber design.

Rousar, D. C.

1971-01-01

287

FEEP micro-thrust balance characterization and testing  

Microsoft Academic Search

A micro-thrust stand developed by the National Physical Laboratory under ESA funding was calibrated and characterized. The balance is based on the nulled-pendulum principle. The thruster is positioned in a constrained pendulum that is free to move only along the line of thrust. A capacitive displacement sensor measures the movement of the pendulum and is connected via a servo closed

S. Rocca; C. Menon; D. Nicolini

2006-01-01

288

The 30-centimeter ion thrust subsystem design manual  

NASA Technical Reports Server (NTRS)

The principal characteristics of the 30-centimeter ion propulsion thrust subsystem technology that was developed to satisfy the propulsion needs of future planetary and early orbital missions are described. Functional requirements and descriptions, interface and performance requirements, and physical characteristics of the hardware are described at the thrust subsystem, BIMOD engine system, and component level.

1979-01-01

289

Parametric study on thrust force of core drill  

Microsoft Academic Search

Drilling-induced delamination is among the major concerns of applying the fiber-reinforced composite materials in various industries. Core drill possesses the advantage for reducing the delamination by distributing the drilling thrust force toward the drill periphery. The thrust force of core drill varying with the conditions in drilling carbon fiber reinforced plastic (CFRP) is experimentally investigated in this study. The experimental

C. C. Tsao; H. Hocheng

2007-01-01

290

Fold-Thrust Belts Earth Structure (2nd Edition), 2004  

E-print Network

When a thrust sheet moves up a stair-step fault, ramp anticlines develop. (a) The cross-sectional trace Duplex Duplex: relatively large displacements. Flat-roofed duplex develops by progressive break- forward faulting. Roof thrust undergoes a sequence of folding and unfolding. Allmendinger #12;© EarthStructure (2nd

291

Vector Fields  

NSDL National Science Digital Library

Vector fields are vectors which change from point to point. A standard example is the velocity of moving air, in other words, wind. For instance, the current wind pattern in the San Francisco area can be found at . This site has a 2-dimensional representation; careful reading of the webpage will tell you at what elevation the wind is shown. How would you represent a vector field in 3 dimensions? What features are important? Some simple examples are shown. Each can be rotated by clicking and dragging with the mouse. Explore!

Ay, Tevian

2006-01-01

292

Cloning vector  

DOEpatents

A vector comprising a filamentous phage sequence containing a first copy of filamentous phage gene X and other sequences necessary for the phage to propagate is disclosed. The vector also contains a second copy of filamentous phage gene X downstream from a promoter capable of promoting transcription in a bacterial host. In a preferred form of the present invention, the filamentous phage is M13 and the vector additionally includes a restriction endonuclease site located in such a manner as to substantially inactivate the second gene X when a DNA sequence is inserted into the restriction site. 2 figures.

Guilfoyle, R.A.; Smith, L.M.

1994-12-27

293

Hydrogeology of thrust faults and crystalline thrust sheets: Results of combined field and modeling studies  

NASA Astrophysics Data System (ADS)

Field, laboratory, and modeling studies of faulted rock yield insight into the hydraulic character of thrust faults. Late-stage faults comprise foliated and subparallel faults, with clay-rich gouge and fracture zones, that yield interpenetrating layers of low-permeability gouge and higher-permeability damage zones. Laboratory testing suggests a permeability contrast of two orders of magnitude between gouge and damage zones. Layers of differing permeability lead to overall permeability anisotropy with maximum permeability within the plane of the fault and minimum permeability perpendicular to the fault plane. Numerical modeling of regional-scale fluid flow and heat transport illustrates the impact of fault zone hydrogeology on fluid flux, fluid pore pressure, and temperature in the vicinity of a crystalline thrust sheet.

Forster, Craig B.; Evans, James P.

294

Global Simulations of the Interaction of Microquasar Jets with a Stellar wind in High-Mass X-ray Binaries  

NASA Astrophysics Data System (ADS)

Jets powered by high-mass X-ray binaries must traverse the powerful wind of the companion star. We present the first global 3-D simulations of jet-wind interaction in high-mass X-ray binaries. We show that the jet can be re-collimated where the internal jet pressure is equal to the wind ram pressure, and beyond the re-collimation, the jet thickness, h, follows from pressure equilibrium between the jet and bow-shock. Based on this analytic jet model, we analyze the effects of jet-wind interaction, bending the jet to an asymptotic angle ??. Through both numerical study and analytic approach, we formularize the ?? as a function of jet power and wind thrust, which can be used to constrain the jet power with known wind parameters. For example, we apply the formula to the case of Cygnus X-1, and show that given wind parameters for the O9.7 Iab companion, the jet power should be larger than 1.47 × 1036 ergs s-1 to keep the jet straight against the wind momentum flux as it is observed by VLBA. We further discuss the case where the initial jet is inclined relative to the binary orbital axis, which shows asymmetric behavior between approaching jet and receding jet from the companion star. We also analyze the case of Cygnus X-3 and show that jet bending is likely negligible unless the jet is significantly less powerful or much wider than currently thought.

Yoon, Doosoo; Heinz, Sebastian

2015-01-01

295

Bouncing Jets  

NASA Astrophysics Data System (ADS)

Contrary to common intuition, free jets of fluid can ``bounce'' off each other on collision in mid-air, through the effect of a lubricating air film that separates the jets. We have developed a simple experimental setup to stably demonstrate and study the non-coalescence of jets on collision. We present the results of an experimental investigation of oblique collision between two silicone oil jets, supported by a simple analytical explanation. Our focus is on elucidating the role of various physical forces at play such as viscous stresses, capillary force and inertia. A parametric study conducted by varying the nozzle diameter, jet velocity, angle of inclination and fluid viscosity reveals the scaling laws for the quantities involved such as contact time. We observed a transition from bouncing to coalescence with an increase in jet velocity and inclination angle. We propose that a balance between the contact time of jets and the time required for drainage of the trapped air film can provide a criterion for transition from non-coalescence to coalescence.

Wadhwa, Navish; Vlachos, Pavlos; Jung, Sunghwan

2011-11-01

296

Thrust and efficiency of a self-field MPD thruster  

NASA Technical Reports Server (NTRS)

Thrust and efficiency of a quasi-steady multi-MW argon MPD thruster are determined for one-millisecond current pulses. Terminal voltage and impulse bit per pulse are measured for a benchmark thruster geometry on a swinging gate thrust stand in a dielectric vacuum tank, at a background pressure of 0.0001 torr, for a range of argon flow rates and arc currents. The quasi-steady thrust data scale quadratically with arc current, and confirm previous estimates of the electromagnetic and electrothermal components of thrust from magnetic and pressure probe measurements. Thruster efficiency is found to increase monotonically with specific impulse, reaching a value of 25% for 4.5 to 6.0 g/sec at 2000 seconds. Results of further experiments show that the inferred specific impulse for voltage fluctuation onset can be increased to 3000 seconds, and the thrust efficiency to above 30%.

Burton, R. L.; Clark, K. E.; Jahn, R. G.

1981-01-01

297

Thrust Measurements for a Pulse Detonation Engine Driven Ejector  

NASA Technical Reports Server (NTRS)

Results of an experimental effort on pulse detonation driven ejectors aimed at probing different aspects of PDE ejector processes, are presented and discussed. The PDE was operated using ethylene as the fuel and an equimolar oxygen/nitrogen mixture as the oxidizer at an equivalence ratio of one. The thrust measurements for the PDE alone are in excellent agreement with experimental and modeling results reported in the literature and serve as a Baseline for the ejector studies. These thrust measurements were then used as a basis for quantifying thrust augmentation for various PDE/ejector setups using constant diameter ejector tubes and various detonation tube/ejector tube overlap distances. The results show that for the geometries studied here, a maximum thrust augmentation of 24% is achieved. The thrust augmentation results are complemented by shadowgraph imaging of the flowfield in the ejector tube inlet area and high frequency pressure transducer measurements along the length of the ejector tube.

Santoro, Robert J.; Pak, Sibtosh; Shehadeh, R.; Saretto, S. R.; Lee, S.-Y.

2005-01-01

298

An Optimal Orthogonal Decomposition Method for Kalman Filter-Based Turbofan Engine Thrust Estimation  

NASA Technical Reports Server (NTRS)

A new linear point design technique is presented for the determination of tuning parameters that enable the optimal estimation of unmeasured engine outputs such as thrust. The engine s performance is affected by its level of degradation, generally described in terms of unmeasurable health parameters related to each major engine component. Accurate thrust reconstruction depends upon knowledge of these health parameters, but there are usually too few sensors to be able to estimate their values. In this new technique, a set of tuning parameters is determined which accounts for degradation by representing the overall effect of the larger set of health parameters as closely as possible in a least squares sense. The technique takes advantage of the properties of the singular value decomposition of a matrix to generate a tuning parameter vector of low enough dimension that it can be estimated by a Kalman filter. A concise design procedure to generate a tuning vector that specifically takes into account the variables of interest is presented. An example demonstrates the tuning parameters ability to facilitate matching of both measured and unmeasured engine outputs, as well as state variables. Additional properties of the formulation are shown to lend themselves well to diagnostics.

Litt, Jonathan S.

2005-01-01

299

An Optimal Orthogonal Decomposition Method for Kalman Filter-Based Turbofan Engine Thrust Estimation  

NASA Technical Reports Server (NTRS)

A new linear point design technique is presented for the determination of tuning parameters that enable the optimal estimation of unmeasured engine outputs, such as thrust. The engine s performance is affected by its level of degradation, generally described in terms of unmeasurable health parameters related to each major engine component. Accurate thrust reconstruction depends on knowledge of these health parameters, but there are usually too few sensors to be able to estimate their values. In this new technique, a set of tuning parameters is determined that accounts for degradation by representing the overall effect of the larger set of health parameters as closely as possible in a least-squares sense. The technique takes advantage of the properties of the singular value decomposition of a matrix to generate a tuning parameter vector of low enough dimension that it can be estimated by a Kalman filter. A concise design procedure to generate a tuning vector that specifically takes into account the variables of interest is presented. An example demonstrates the tuning parameters ability to facilitate matching of both measured and unmeasured engine outputs, as well as state variables. Additional properties of the formulation are shown to lend themselves well to diagnostics.

Litt, Jonathan S.

2007-01-01

300

An Optimal Orthogonal Decomposition Method for Kalman Filter-Based Turbofan Engine Thrust Estimation  

NASA Technical Reports Server (NTRS)

A new linear point design technique is presented for the determination of tuning parameters that enable the optimal estimation of unmeasured engine outputs, such as thrust. The engine's performance is affected by its level of degradation, generally described in terms of unmeasurable health parameters related to each major engine component. Accurate thrust reconstruction depends on knowledge of these health parameters, but there are usually too few sensors to be able to estimate their values. In this new technique, a set of tuning parameters is determined that accounts for degradation by representing the overall effect of the larger set of health parameters as closely as possible in a least squares sense. The technique takes advantage of the properties of the singular value decomposition of a matrix to generate a tuning parameter vector of low enough dimension that it can be estimated by a Kalman filter. A concise design procedure to generate a tuning vector that specifically takes into account the variables of interest is presented. An example demonstrates the tuning parameters ability to facilitate matching of both measured and unmeasured engine outputs, as well as state variables. Additional properties of the formulation are shown to lend themselves well to diagnostics.

Litt, Jonathan S.

2007-01-01

301

Jet-diffuser Ejector - Attached Nozzle Design  

NASA Technical Reports Server (NTRS)

Attached primary nozzles were developed to replace the detached nozzles of jet-diffuser ejectors. Slotted primary nozzles located at the inlet lip and injecting fluid normal to the thrust axis, and rotating the fluid into the thrust direction using the Coanda Effect were investigated. Experiments indicated excessive skin friction or momentum cancellation due to impingement of opposing jets resulted in performance degradation. This indicated a desirability for location and orientation of the injection point at positions removed from the immediate vicinity of the inlet surface, and at an acute angle with respect to the thrust axis. Various nozzle designs were tested over a range of positions and orientations. The problems of aircraft integration of the ejector, and internal and external nozzle losses were also considered and a geometry for the attached nozzles was selected. The effect of leaks, protrusions, and asymmetries in the ejector surfaces was examined. The results indicated a relative insensitivity to all surface irregularities, except for large protrusions at the throat of the ejector.

Alperin, M.; Wu, J. J.

1980-01-01

302

Exoskeletal Engine Concept: Feasibility Studies for Medium and Small Thrust Engines  

NASA Technical Reports Server (NTRS)

The exoskeletal engine concept is one in which the shafts and disks are eliminated and are replaced by rotating casings that support the blades in spanwise compression. Omission of the shafts and disks leads to an open channel at the engine centerline. This has immense potential for reduced jet noise and for the accomodation of an alternative form of thruster for use in a combined cycle. The use of ceramic composite materials has the potential for significantly reduced weight as well as higher working temperatures without cooling air. The exoskeletal configuration is also a natural stepping-stone to complete counter-rotating turbomachinery. Ultimately this will lead to reductions in weight, length, parts count and improved efficiency. The feasibility studies are in three parts. Part I-Systems and Component Requirements addressed the mechanical aspects of components from a functionality perspective. This effort laid the groundwork for preliminary design studies. Although important, it is not felt to be particularly original, and has therefore not been included in the current overview. Part 2-Preliminary Design Studies turned to some of the cycle and performance issues inherent in an exoskeletal configuration and some initial attempts at preliminary design of turbomachinery were described. Twin-spoon and single-spool 25.800-lbf-thrust turbofans were used as reference vehicles in a mid-size commercial subsonic category in addition to a single-spool 5,000-lbf-thrust turbofan that represented a general aviation application. The exoskeletal engine, with its open centerline, has tremendous potential for noise suppression and some preliminary analysis was done which began to quantify the benefits. Part 3-Additional Preliminary Design Studies revisited the design of single-spool 25,800-lbf-thrust turbofan configurations, but in addition to the original FPR = 1.6 and BPR = 5.1 reference engine, two additional configurations used FPR = 2.4 and BPR = 3.0 and FPR = 3.2 and BPR = 2.0 were investigated. The single-spool 5,000-lbf-thrust turbofan was refined and the small engine study was extended to include a 2,000-lbf-thrust turbojet. More attention was paid to optimizing the turbomachinery. Turbine cooling flows were eliminated, in keeping with the use of uncooled CMC material in exoskeletal engines. The turbine performance parameters moved much closer to the nominal target values, demonstrating the great benefits to the cycle of uncooled turbines.

Halliwell, Ian

2001-01-01

303

Exoskeletal Engine Concept: Feasibility Studies for Medium and Small Thrust Engines  

NASA Technical Reports Server (NTRS)

The exoskeletal engine concept is one in which the shafts and disks are eliminated and are replaced by rotating casings that support the blades in spanwise compression. Omission of the shafts and disks leads to an open channel at the engine centerline. This has immense potential for reduced jet noise and for the accommodation of an alternative form of thruster for use in a combined cycle. The use of ceramic composite materials has the potential for significantly reduced weight as well as higher working temperatures without cooling air. The exoskeletal configuration is also a natural stepping-stone to complete counter-rotating turbomachinery. Ultimately this will lead to reductions in weight, length, parts count and improved efficiency. The feasibility studies are in three parts. Part 1: Systems and Component Requirements addressed the mechanical aspects of components from a functionality perspective. This effort laid the groundwork for preliminary design studies. Although important, it is not felt to be particularly original, and has therefore not been included in the current overview. Part 2: Preliminary Design Studies turned to some of the cycle and performance issues inherent in an exoskeletal configuration and some initial attempts at preliminary design of turbomachinery were described. Twin-spoon and single-spool 25,800-lbf-thrust turbofans were used as reference vehicles in a mid-size commercial subsonic category in addition to a single-spool 5,000-lbf-thrust turbofan that represented a general aviation application. The exoskeletal engine, with its open centerline, has tremendous potential for noise suppression and some preliminary analysis was done which began to quantify the benefits. Part 3: Additional Preliminary Design Studies revisited the design of single-spool 25,800-lbf-thrust turbofan configurations, but in addition to the original FPR = 1.6 and BPR = 5.1 reference engine. two additional configurations used FPR = 2.4 and BPR = 3.0 and FPR = 3.2 and BPR = 2.0 were investigated. The single-spool 5.000-lbf-thrust turbofan was refined and the small engine study was extended to include a 2,000-lbf-thrust turbojet. More attention was paid to optimizing the turbomachinery. Turbine cooling flows were eliminated, in keeping with the use of uncooled CMC materials in exoskeletal engines. The turbine performance parameters moved much closer to the nominal target values, demonstrating the great benefits to the cycle of uncooled turbines.

Halliwell, Ian

2001-01-01

304

Vector quantization  

NASA Technical Reports Server (NTRS)

During the past ten years Vector Quantization (VQ) has developed from a theoretical possibility promised by Shannon's source coding theorems into a powerful and competitive technique for speech and image coding and compression at medium to low bit rates. In this survey, the basic ideas behind the design of vector quantizers are sketched and some comments made on the state-of-the-art and current research efforts.

Gray, Robert M.

1989-01-01

305

14 CFR Appendix I to Part 25 - Installation of an Automatic Takeoff Thrust Control System (ATTCS)  

...Installation of an Automatic Takeoff Thrust Control System (ATTCS) I Appendix...Installation of an Automatic Takeoff Thrust Control System (ATTCS) I25...2Definitions. (a) Automatic Takeoff Thrust Control System (ATTCS)....

2014-01-01

306

14 CFR Appendix I to Part 25 - Installation of an Automatic Takeoff Thrust Control System (ATTCS)  

Code of Federal Regulations, 2013 CFR

...Installation of an Automatic Takeoff Thrust Control System (ATTCS) I Appendix...Installation of an Automatic Takeoff Thrust Control System (ATTCS) I25...2Definitions. (a) Automatic Takeoff Thrust Control System (ATTCS)....

2013-01-01

307

14 CFR 23.934 - Turbojet and turbofan engine thrust reverser systems tests.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Turbojet and turbofan engine thrust reverser systems... Powerplant General § 23.934 Turbojet and turbofan engine thrust reverser systems tests. Thrust reverser systems of turbojet or turbofan engines must meet the...

2010-01-01

308

14 CFR 25.934 - Turbojet engine thrust reverser system tests.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Turbojet engine thrust reverser system tests...Powerplant General § 25.934 Turbojet engine thrust reverser system tests. Thrust reversers installed on turbojet engines must meet the...

2010-01-01

309

A computational study of thrust augmenting ejectors based on a viscous-inviscid approach  

NASA Technical Reports Server (NTRS)

A viscous-inviscid interaction technique is advocated as both an efficient and accurate means of predicting the performance of two-dimensional thrust augmenting ejectors. The flow field is subdivided into a viscous region that contains the turbulent jet and an inviscid region that contains the ambient fluid drawn into the device. The inviscid region is computed with a higher-order panel method, while an integral method is used for the description of the viscous part. The strong viscous-inviscid interaction present within the ejector is simulated in an iterative process where the two regions influence each other en route to a converged solution. The model is applied to a variety of parametric and optimization studies involving ejectors having either one or two primary jets. The effects of nozzle placement, inlet and diffuser shape, free stream speed, and ejector length are investigated. The inlet shape for single jet ejectors is optimized for various free stream speeds and Reynolds numbers. Optimal nozzle tilt and location are identified for various dual-ejector configurations.

Lund, Thomas S.; Tavella, Domingo A.; Roberts, Leonard

1987-01-01

310

Reattachment of a three-dimensional, incompressible jet to an adjacent axisymmetric inclined surface  

NASA Astrophysics Data System (ADS)

A study was made of the fluid mechanics of a thrust reverser jet reattaching to an aircraft nozzle afterbody. The problem basically involves the Coanda effect flow of a three dimensional, incompressible jet to an adjacent axisymmetric, inclined surface. The equations were derived in integral form and programmed for numerical solution for the case of an exhaust flow with no opposing free stream flow. Test data are reported for a scale model of a nozzle afterbody exhausting against a target-type thrust reverser. Data are presented for surface pressure coefficient at various points along the model.

Niemi, E. E., Jr.

1983-03-01

311

Business Jet  

NASA Technical Reports Server (NTRS)

The Citation Jet, developed by Cessna Aircraft Company, Wichita, KS, is the first business jet to employ Langley Research Center's natural laminar flow (NLF) technology. NLF reduces drag and therefore saves fuel by using only the shape of the wing to keep the airflow smooth, or laminar. This reduces friction between the air and wing, and therefore, reduces drag. NASA's Central Industrial Applications Center, Rural Enterprises, Inc., Durant, OK, its Kansas affiliate, and Wichita State University assisted in the technology transfer.

1991-01-01

312

Transonic Performance Characteristics of Several Jet Noise Suppressors  

NASA Technical Reports Server (NTRS)

An investigation of the transonic performance characteristics of several noise-suppressor configurations has been conducted in the Langley 16-foot transonic tunnel. The models were tested statically and over a Mach number range from 0.70 to 1.05 at an angle of attack of 0 deg. The primary jet total-pressure ratio was varied from 1.0 (jet off) to about 4.5. The effect of secondary air flow on the performance of two of the configurations was investigated. A hydrogen peroxide turbojet-engine simulator was used to supply the hot-jet exhaust. An 8-lobe afterbody with centerbody, short shroud, and secondary air had the highest thrust-minus-drag coefficients of the six noise-suppressor configurations tested. The 12-tube and 12-lobe afterbodies had the lowest internal losses. The presence of an ejector shroud partially shields the external pressure distribution of the 8-lobe after-body from the influence of the primary jet. A ring-airfoil shroud increased the static thrust of the annular nozzle but generally decreased the thrust minus drag at transonic Mach numbers.

Schmeer, James W.; Salters, Leland B., Jr.; Cassetti, Marlowe D.

1960-01-01

313

Evaluation of thrust measurement techniques for dielectric barrier discharge actuators  

NASA Astrophysics Data System (ADS)

Despite its popularity in the recent literature, plasma actuators lack a consistent study to identify limitations, and remedy thereof, of various thrust measurement techniques. This paper focuses on comparing two different experimental techniques commonly used to measure the global, plasma-induced thrust. A force balance is used to make a direct measurement of the thrust produced, which is then compared with a control volume analysis on data obtained through particle image velocimetry. The local velocity measured by particle image velocimetry is also validated with a fine-tip pressure probe. For the direct thrust measurements, the effect of varying the actuator plate length upon which the induced flow acts is investigated. The results from these tests show that the length of the actuator plate is most influential at higher voltages with the measured thrust increasing as much as 20 % for a six times reduction in the length of the plate. For the indirect thrust measurement, the influence of the control volume size is analyzed. When the two methods are compared against each other, good agreement is found when the control volume size has a sufficient downstream extent. Also, the discharge length is optically measured using visible light emission. A linear correlation is found between the discharge length and the thrust measurements for the actuator configurations studied. Finally, the energy conversion efficiency curve for a representative actuator is also presented.

Durscher, Ryan; Roy, Subrata

2012-10-01

314

Thrust Stand Characterization of the NASA Evolutionary Xenon Thruster (NEXT)  

NASA Technical Reports Server (NTRS)

Direct thrust measurements have been made on the NASA Evolutionary Xenon Thruster (NEXT) ion engine using a standard pendulum style thrust stand constructed specifically for this application. Values have been obtained for the full 40-level throttle table, as well as for a few off-nominal operating conditions. Measurements differ from the nominal NASA throttle table 10 (TT10) values by 3.1 percent at most, while at 30 throttle levels (TLs) the difference is less than 2.0 percent. When measurements are compared to TT10 values that have been corrected using ion beam current density and charge state data obtained at The Aerospace Corporation, they differ by 1.2 percent at most, and by 1.0 percent or less at 37 TLs. Thrust correction factors calculated from direct thrust measurements and from The Aerospace Corporation s plume data agree to within measurement error for all but one TL. Thrust due to cold flow and "discharge only" operation has been measured, and analytical expressions are presented which accurately predict thrust based on thermal thrust generation mechanisms.

Diamant, Kevin D.; Pollard, James E.; Crofton, Mark W.; Patterson, Michael J.; Soulas, George C.

2010-01-01

315

Propeller thrust analysis using Prandtl's lifting line theory, a comparison between the experimental thrust and the thrust predicted by Prandtl's lifting line theory  

NASA Astrophysics Data System (ADS)

The lifting line theory was first developed by Prandtl and was used primarily on analysis of airplane wings. Though the theory is about one hundred years old, it is still used in the initial calculations to find the lift of a wing. The question that guided this thesis was, "How close does Prandtl's lifting line theory predict the thrust of a propeller?" In order to answer this question, an experiment was designed that measured the thrust of a propeller for different speeds. The measured thrust was compared to what the theory predicted. In order to do this experiment and analysis, a propeller needed to be used. A walnut wood ultralight propeller was chosen that had a 1.30 meter (51 inches) length from tip to tip. In this thesis, Prandtl's lifting line theory was modified to account for the different incoming velocity depending on the radial position of the airfoil. A modified equation was used to reflect these differences. A working code was developed based on this modified equation. A testing rig was built that allowed the propeller to be rotated at high speeds while measuring the thrust. During testing, the rotational speed of the propeller ranged from 13-43 rotations per second. The thrust from the propeller was measured at different speeds and ranged from 16-33 Newton's. The test data were then compared to the theoretical results obtained from the lifting line code. A plot in Chapter 5 (the results section) shows the theoretical vs. actual thrust for different rotational speeds. The theory over predicted the actual thrust of the propeller. Depending on the rotational speed, the error was: at low speeds 36%, at low to moderate speeds 84%, and at high speeds the error increased to 195%. Different reasons for these errors are discussed.

Kesler, Steven R.

316

Thrust stand for high-power electric propulsion devices  

NASA Astrophysics Data System (ADS)

A thrust stand for use with magnetoplasmadynamic (MPD) thrusters operated at powers up to 250 kW steady state has been built and tested. The stand was based on an inverted pendulum configuration which resulted in large displacements and high resolution. Up to 50 mm of deflection was observed under a force of 5 N. This large range of displacement significantly reduced the effects of facility induced vibrations on thrust measurements. A remotely operated system was provided for in situ calibration of the thrust stand prior to and immediately after data were obtained. Calibrations showed that thrust measurements were linear and repeatable to within a fraction of 1%. Structural distortions of the vacuum facility due to pumpdown were detected with an inclinometer located in the thrust stand base. Slope deviations as small as 10 arcsec could be compensated using a remotely controlled leveling motor. Early problems with magnetically induced tares caused by the thruster discharge current were reduced by rerouting high-current cables to decrease stray fields. Tares due to discharge current were on the order of 26 mN at 3000 A, and those due to an applied field current were 63 mN at 1400 A. The thrust stand was used with a water-cooled, applied field, steady-state MPD device at power levels up to 125 kW. Hot thruster firings as long as 1 h were performed. By precisely maintaining a level thrust stand base, thermal drift was held to about 2% of the full scale reading over this period. The remaining thermal drift could be subtracted from the thrust measurement to further reduce systematic error. Tares caused by the applied magnetic field were similarly removed. By subtracting tabulated discharge current magnetic tares, thrust measurement uncertainty was reduced to approximately 2% of the measured value.

Haag, T. W.

1991-05-01

317

Powered Descent Guidance with General Thrust-Pointing Constraints  

NASA Technical Reports Server (NTRS)

The Powered Descent Guidance (PDG) algorithm and software for generating Mars pinpoint or precision landing guidance profiles has been enhanced to incorporate thrust-pointing constraints. Pointing constraints would typically be needed for onboard sensor and navigation systems that have specific field-of-view requirements to generate valid ground proximity and terrain-relative state measurements. The original PDG algorithm was designed to enforce both control and state constraints, including maximum and minimum thrust bounds, avoidance of the ground or descent within a glide slope cone, and maximum speed limits. The thrust-bound and thrust-pointing constraints within PDG are non-convex, which in general requires nonlinear optimization methods to generate solutions. The short duration of Mars powered descent requires guaranteed PDG convergence to a solution within a finite time; however, nonlinear optimization methods have no guarantees of convergence to the global optimal or convergence within finite computation time. A lossless convexification developed for the original PDG algorithm relaxed the non-convex thrust bound constraints. This relaxation was theoretically proven to provide valid and optimal solutions for the original, non-convex problem within a convex framework. As with the thrust bound constraint, a relaxation of the thrust-pointing constraint also provides a lossless convexification that ensures the enhanced relaxed PDG algorithm remains convex and retains validity for the original nonconvex problem. The enhanced PDG algorithm provides guidance profiles for pinpoint and precision landing that minimize fuel usage, minimize landing error to the target, and ensure satisfaction of all position and control constraints, including thrust bounds and now thrust-pointing constraints.

Carson, John M., III; Acikmese, Behcet; Blackmore, Lars

2013-01-01

318

Electric sail control mode for amplified transverse thrust  

NASA Astrophysics Data System (ADS)

The electric solar wind sail produces thrust by centrifugally spanned high voltage tethers interacting with the solar wind protons. The sail attitude can be controlled and attitude maneuvers are possible by tether voltage modulation synchronous with the sail rotation. Especially, the sail can be inclined with respect to the solar wind direction to obtain transverse thrust to change the osculating orbit angular momentum. Such an inclination has to be maintained by a continual control voltage modulation. Consequently, the tether voltage available for the thrust is less than the maximum voltage provided by the power system. Using a spherical pendulum as a model for a single rotating tether, we derive analytical estimations for the control efficiency for two separate sail control modes. One is a continuous control modulation that corresponds to strictly planar tether tip motion. The other is an on-off modulation with the tether tip moving along a closed loop on a saddle surface. The novel on-off mode is introduced here to both amplify the transverse thrust and reduce the power consumption. During the rotation cycle, the maximum voltage is applied to the tether only over two thrusting arcs when most of the transverse thrust is produced. In addition to the transverse thrust, we obtain the thrusting angle and electric power consumption for the two control modes. It is concluded that while the thrusting angle is about half of the sail inclination for the continuous modulation it approximately equals to the inclination angle for the on-off modulation. The efficiency of the on-off mode is emphasized when power consumption is considered, and the on-off mode can be used to improve the propulsive acceleration through the reduced power system mass.

Toivanen, P.; Janhunen, P.; Envall, J.

2015-01-01

319

Jet observables without jet algorithms  

E-print Network

We introduce a new class of event shapes to characterize the jet-like structure of an event. Like traditional event shapes, our observables are infrared/collinear safe and involve a sum over all hadrons in an event, but ...

Bertolini, Daniele

320

Thrust stand for high-power electric propulsion devices  

NASA Technical Reports Server (NTRS)

This paper describes a new high-power thrust stand developed for use with high-power (up to 250 kW) magnetoplasmadynamic (MPD) thrusters, which is installed in a high-vacuum MPD facility at Lewis Research Center. The design of the stand is based on inverted pendulum configuration, with the result of large displacements and high resolution. Calibration results showed that thrust measurements were linear and repeatable to within a fraction of 1 percent. The thrust stand was used for testing water-cooled MPD thrusters at power levels up to 125 kW. The thruster, however, is quite well suited for testing other types of electric propulsion devices.

Haag, T. W.

1991-01-01

321

The Role of Stress Interaction in Thrust and Subduction Earthquakes  

NASA Astrophysics Data System (ADS)

Key features of thrust earthquake triggering, inhibition, and clustering can be explained by Coulomb stress changes. Whereas slip on surface-cutting thrust faults drops the stress in most of the adjacent crust, slip on blind thrust faults increases the stress on some nearby zones, particularly above the source fault. Blind thrusts can thus trigger slip on secondary faults at shallow depth, and typically produce broadly distributed aftershocks. Short thrust ruptures are effective at triggering earthquakes of similar size on adjacent thrust faults. We calculate that during a progressive thrust sequence in central California during 1982-1985, the Mw=6.7 Coalinga earthquake brought the subsequent 1983 Mw=6.0 Nuñez and 1985 Mw=6.0 Kettleman Hills ruptures 10 and 1 bars closer to Coulomb failure. On a larger scale, slip on major strike-slip faults modulates the stress acting on nearby thrust faults. We calculate that the 1857 Mw=7.9 Fort Tejon San Andreas earthquake and subsequent interseismic slip brought the Coalinga fault ~1 bar closer to failure, and inhibited failure elsewhere on the Coast Ranges thrust faults. The 1857 event also promoted failure on the White Wolf thrust fault by 8 bars, which ruptured in the 1952 Mw=7.3 Kern County shock. The idealized stress-change calculations also explain key features of seismicity accompanying large subduction events. Subduction zone ruptures are calculated to promote normal faulting events in the outer rise, and to promote thrust faulting events on the periphery of the seismic rupture and on its downdip extension. These features are evident in aftershocks of the 1957 Mw=9.1 Aleutian and other large subduction earthquakes. We further examine stress changes on the rupture surface imparted by the 1960 Mw=9.5 and 1995 Mw=8.1 Chile earthquakes, for which detailed slip models are available. Calculated Coulomb stress increases of 2-20-bars correspond closely to sites of aftershocks and postseismic slip, whereas aftershocks are absent where the stress drops by more than 10 bars. We thus argue that stress transfer exerts a control on the seismicity of thrust faults across a broad spectrum of spatial and temporal scales.

Stein, R. R.; Lin, J.

2003-12-01

322

ALBANIA: Thrust and backthrust systems of external Albanides: Examples  

SciTech Connect

External Albanides have proved as an oil/gas province in a certain limited area. Better understanding of thrusting and backthrusting systems and how both systems work, could improve objectives for exploration beyond actual discoveries. Backthrusting is not seen any more typical for Cenozoic sediments, where buried front of thrust faulted belts are very active. Mesozoic rocks, that are dominated by westward thrust propagation are also affected by backthrusting, thus leaving more space for other units accommodation. New concepts postulated are based on Deep Holes, Seismic Data, Outcrops and Spot Imagery. Among onshore examples, some of them cross existing fields.

Bega, Z.; Janopulli, V. [OEMV Exploration, Tirana (Albania)

1995-08-01

323

Multiphysics Thrust Chamber Modeling for Nuclear Thermal Propulsion  

NASA Technical Reports Server (NTRS)

The objective of this effort is to develop an efficient and accurate thermo-fluid computational methodology to predict environments for a solid-core, nuclear thermal engine thrust chamber. The computational methodology is based on an unstructured-grid, pressure-based computational fluid dynamics formulation. A two-pronged approach is employed in this effort: A detailed thermo-fluid analysis on a multi-channel flow element for mid-section corrosion investigation; and a global modeling of the thrust chamber to understand the effect of heat transfer on thrust performance. Preliminary results on both aspects are presented.

Wang, Ten-See; Cheng, Gary; Chen, Yen-Sen

2006-01-01

324

The wake structure and thrust performance of a rigid low-aspect-ratio pitching panel  

NASA Astrophysics Data System (ADS)

Thrust performance and wake structure were investigated for a rigid rectangular panel pitching about its leading edge in a free stream. For ReC = O(104), thrust coefficient was found to depend primarily on Strouhal number St and the aspect ratio of the panel AR. Propulsive efficiency was sensitive to aspect ratio only for AR less than 0.83; however, the magnitude of the peak efficiency of a given panel with variation in Strouhal number varied inversely with the amplitude to span ratio A/S, while the Strouhal number of optimum efficiency increased with increasing A/S. Peak efficiencies between 9% and 21% were measured. Wake structures corresponding to a subset of the thrust measurements were investigated using dye visualization and digital particle image velocimetry. In general, the wakes divided into two oblique jets; however, when operating at or near peak efficiency, the near wake in many cases represented a Kn vortex street with the signs of the vortices reversed. The three-dimensional structure of the wakes was investigated in detail for AR = 0.54, A/S = 0.31 and ReC = 640. Three distinct wake structures were observed with variation in Strouhal number. For approximately 0.20 0.25, a reorganization of some of the spanwise vorticity yielded a bifurcating wake formed by trains of vortex rings connected to the tips of the horseshoes. For St > 0.5, an additional structure formed from a perturbation of the streamwise leg which caused a spanwise expansion. The wake model paradigm established here is robust with variation in Reynolds number and is consistent with structures observed for a wide variety of unsteady flows. Movies are available with the online version of the paper.

Buchholz, James H. J.; Smits, Alexander J.

325

Experimental Investigation of Thrust Faults in Homalite  

NASA Astrophysics Data System (ADS)

A sound interplay between experimental observations and numerical simulations can reveal a much greater insight into a scientific problem than either methodology alone, where numerics may direct the next experiment or vise-versa. With this motivation, experiments are designed to study the ground motion of thrust faults near the fault trace and to compare with true-to-life numerical simulation results. Through the application of an external load with a press to a thin sheet of Homalite, a high-density polymer, and discharging a capacitor across a wire, slip is initiated along a carefully treated interface. Several key parameters such as the angle of the interface and the applied load may be varied to achieve fundamentally different wave phenomenon, namely a super shear or sub-Rayleigh event. Laser vibrometers are used to record the velocity normal to the free surface on the hanging wall and the footwall. With high-speed cameras, photoelastic fringes are obtained in transmission through the Homalite slab, outputting information about the stress state in the material. Discoveries on the material response to the applied wave field are possible with the information from the photoelastic images in conjunction with the velocity traces, especially in the differences between a super shear and a sub Rayleigh event. Experimental results validate the salient features of the numerical simulations in 2D and even more closely in 3D.

Gabuchian, V.; Rosakis, A.; Lapusta, N.; Oglesby, D. D.

2010-12-01

326

Cretaceous biostratigraphy in the Wyoming thrust belt.  

USGS Publications Warehouse

In the Cretaceous section of the thrust belt, fossils are especially useful for dating and correlating repetitive facies of different ages in structurally complex terrain. The biostratigraphic zonation for the region is based on megafossils (chiefly ammonites) , which permit accurate dating and correlation of outcrop sections, and which have been calibrated with the radiometric time scale for the Western Interior. Molluscan and vertebrate zone fossils are difficult to obtain from the subsurface, however, and ammonites are restricted to rocks of marine origin. Palynomorphs (plant microfossils) have proven to be the most valuable fossils in the subsurface because they can be recovered from drill cuttings. Palynomorphs also are found in both marine and nonmarine rocks and can be used for correlation between facies. Stratigraphic ranges of selected Cretaceous marine and nonmarine palynomorphs in previously designated reference sections in Fossil Basin, Wyoming are correlated with the occurrence of ammonites and other zone fossils in the same sections. These correlations can be related to known isotopic ages, and they contribute to the calibration of palynomorph ranges in the Cretaceous of the Western Interior. -from Authors

Nichols, D.J.; Jacobson, S.R.

1982-01-01

327

$W/Z$ + jets results from CDF  

SciTech Connect

The CDF Collaboration has a comprehensive program of studying the production of vector bosons, W and Z, in association with energetic jets. Excellent understanding of the standard model W/Z+jets and W/Z+c,b-jets processes is of paramount importance for the top quark physics and for the Higgs boson and many new physics searches. We review the latest CDF results on Z-boson production in association with inclusive and b-quark jets, study of the p{sub T} balance in Z+jet events, and a measurement of the W+charm production cross section. The results are based on 4-5 fb{sup -1} of data and compared to various Monte Carlo and next-to-leading order perturbative QCD predictions.

Camarda, Stefano; /Barcelona, IFAE

2010-01-01

328

53. THRUST SECTION HEATER AND GASEOUS NITROGEN PURGE CONTROLS ON ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

53. THRUST SECTION HEATER AND GASEOUS NITROGEN PURGE CONTROLS ON EAST SIDE OF LAUNCH DECK. LAUNCHER IN BACKGROUND. - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

329

Construction and performance of an inverted pendulum thrust balance  

E-print Network

The objective of the work in this thesis was to devise a means of profiling the thrust of the MIT Space Propulsion Lab's (SPL) Diverging Cusped Field (DCF) thruster and, more generally, other thrusters of similar size and ...

Tartler, Brett R. (Brett Robert)

2010-01-01

330

Thrust Network Analysis : exploring three-dimensional equilibrium  

E-print Network

This dissertation presents Thrust Network Analysis, a new methodology for generating compression-only vaulted surfaces and networks. The method finds possible funicular solutions under gravitational loading within a defined ...

Block, Philippe (Philippe Camille Vincent)

2009-01-01

331

Synthetic Jets  

NASA Technical Reports Server (NTRS)

Current investigation of synthetic jets and synthetic jets in cross-flow examined the effects of orifice geometry and dimensions, momentum-flux ratio, cluster of orifices, pitch and yaw angles as well as streamwise development of the flow field. This comprehensive study provided much needed experimental information related to the various control strategies. The results of the current investigation on isolated and clustered synthetic jets with and without cross-flow will be further analyzed and documented in detail. Presentations at national conferences and publication of peer- reviewed journal articles are also expected. Projected publications will present both the mean and turbulent properties of the flow field, comparisons made with the data available in an open literature, as well as recommendations for the future work.

Milanovic, Ivana M.

2003-01-01

332

Pipeline vectorization  

Microsoft Academic Search

This paper presents pipeline vectorization, amethod for synthesizing hardware pipelines based on softwarevectorizing compilers. The method improves eciencyand ease of development of hardware designs, particularlyfor users with little electronics design experience. We proposeseveral loop transformations to customize pipelinesto meet hardware resource constraints, while maximizingavailable parallelism. For run-time recongurable systems,we apply hardware specialization to increase...

Markus Weinhardt; Wayne Luk

2001-01-01

333

Thrust Performance of an Ideal Pulse Detonation Engine  

Microsoft Academic Search

Quasi-steady and two-dimensional unsteady formulations of the problem on the operation cycle of a pulse detonation engine are derived. A formula for the specific impulse is obtained, and the thrust performance of the engine is calculated. It is found that the thrust performance of this engine for flight Mach numbers M ? [0; 3.6] and compression ratios p2\\/p1 ? [1;

V. V. Mitrofanov; S. A. Zhdan

2004-01-01

334

Measurements of the b quark forward-backward asymmetry around the Z $^0$ peak using jet charge and vertex charge  

Microsoft Academic Search

The b quark forward-backward asymmetry has been measured using approximately four million hadronic Z$^0$ decays collected with the OPAL detector at LEP. Both jet charge and vertex charge were used to estimate whether the b quark was produced in the forward or backward thrust hemisphere. The measured values corrected to the hadron-level thrust axis are \\\\[ \\\\begin{array}{llll} A^{\\\\rm b}_{\\\\rm FB}

Gideon Alexander; J Allison; N Altekamp; K A Ametewee; K J Anderson; S Anderson; S Arcelli; S Asai; D A Axen; Georges Azuelos; A H Ball; E Barberio; R J Barlow; R Bartoldus; J Richard Batley; J Bechtluft; C Beeston; T Behnke; A N Bell; K W Bell; G Bella; Stanislaus Cornelius Maria Bentvelsen; P Berlich; Siegfried Bethke; O Biebel; A Biguzzi; S D Bird; Volker Blobel; Ian J Bloodworth; J E Bloomer; M Bobinski; P Bock; H M Bosch; M Boutemeur; B T Bouwens; S Braibant; R M Brown; Helfried J Burckhart; C Burgard; R Bürgin; P Capiluppi; R K Carnegie; A A Carter; J R Carter; C Y Chang; D G Charlton; D Chrisman; P E L Clarke; I Cohen; J E Conboy; O C Cooke; M Cuffiani; S Dado; C Dallapiccola; G M Dallavalle; S De Jong; L A del Pozo; Klaus Desch; M S Dixit; E do Couto e Silva; M Doucet; E Duchovni; G Duckeck; I P Duerdoth; D Eatough; J E G Edwards; P G Estabrooks; H G Evans; M Evans; Franco Luigi Fabbri; M Fanti; P Fath; A A Faust; F Fiedler; M Fierro; H M Fischer; R Folman; D G Fong; M Foucher; A Fürtjes; P Gagnon; A Gaidot; J W Gary; J Gascon; S M Gascon-Shotkin; N I Geddes; C Geich-Gimbel; F X Gentit; T Geralis; G Giacomelli; P Giacomelli; R Giacomelli; V Gibson; W R Gibson; D M Gingrich; D A Glenzinski; J Goldberg; M J Goodrick; W Gorn; C Grandi; E Gross; Jacob Grunhaus; M Gruwé; C Hajdu; G G Hanson; M Hansroul; M Hapke; C K Hargrove; P A Hart; C Hartmann; M Hauschild; C M Hawkes; R Hawkings; Richard J Hemingway; M Herndon; G Herten; R D Heuer; M D Hildreth; J C Hill; S J Hillier; T Hilse; P R Hobson; R James Homer; A K Honma; D Horváth; R Howard; R E Hughes-Jones; D E Hutchcroft; P Igo-Kemenes; D C Imrie; M R Ingram; K Ishii; A Jawahery; P W Jeffreys; H Jeremie; Martin Paul Jimack; A Joly; C R Jones; G Jones; M Jones; R W L Jones; U Jost; P Jovanovic; T R Junk; D A Karlen; K Kawagoe; T Kawamoto; Richard K Keeler; R G Kellogg; B W Kennedy; J Kirk; S Kluth; T Kobayashi; M Kobel; D S Koetke; T P Kokott; M Kolrep; S Komamiya; T Kress; P Krieger; J Von Krogh; P Kyberd; G D Lafferty; H Lafoux; R Lahmann; W P Lai; D Lanske; J Lauber; S R Lautenschlager; J G Layter; D Lazic; A M Lee; E Lefebvre; Daniel Lellouch; J Letts; L Levinson; C Lewis; S L Lloyd; F K Loebinger; G D Long; Michael J Losty; J Ludwig; A Macchiolo; A L MacPherson; A Malik; M Mannelli; S Marcellini; C Markus; A J Martin; J P Martin; G Martínez; T Mashimo; W Matthews; P Mättig; W J McDonald; J A McKenna; E A McKigney; T J McMahon; A I McNab; R A McPherson; F Meijers; S Menke; F S Merritt; H Mes; J Meyer; Aldo Michelini; G Mikenberg; D J Miller; R Mir; W Mohr; A Montanari; T Mori; M Morii; U Müller; K Nagai; I Nakamura; H A Neal; B Nellen; B Nijjhar; R Nisius; S W O'Neale; F G Oakham; F Odorici; H O Ögren; N J Oldershaw; T Omori; M J Oreglia; S Orito; J Pálinkás; G Pásztor; J R Pater; G N Patrick; J Patt; M J Pearce; S Petzold; P Pfeifenschneider; J E Pilcher; James L Pinfold; D E Plane; P R Poffenberger; B Poli; A Posthaus; H Przysiezniak; D L Rees; D Rigby; S Robertson; S A Robins; N L Rodning; J M Roney; A M Rooke; E Ros; A M Rossi; M Rosvick; P Routenburg; Y Rozen; K Runge; O Runólfsson; U Ruppel; D R Rust; R Rylko; K Sachs; E Sarkisyan-Grinbaum; M Sasaki; C Sbarra; A D Schaile; O Schaile; F Scharf; P Scharff-Hansen; P Schenk; B Schmitt; S Schmitt; M Schröder; H C Schultz-Coulon; M Schulz; M Schumacher; P Schütz; W G Scott; T G Shears; B C Shen; C H Shepherd-Themistocleous; P Sherwood; G P Siroli; A Sittler; A Skillman; A Skuja; A M Smith; T J Smith; G A Snow; Randall J Sobie; S Söldner-Rembold; R W Springer; M Sproston; A Stahl; M Steiert; K Stephens; J Steuerer; B Stockhausen; D Strom; P Szymanski; R Tafirout; S D Talbot; S Tanaka; P Taras; S Tarem; M Thiergen; M A Thomson; E Von Törne; S Towers; I Trigger; T Tsukamoto; E Tsur; A S Turcot; M F Turner-Watson; P Utzat; R Van Kooten; G Vasseur; M Verzocchi; P Vikas; M G Vincter; E H Vokurka; F Wäckerle; A Wagner; C P Ward; D R Ward; J J Ward; P M Watkins; A T Watson; N K Watson; P S Wells; N Wermes; J S White; B Wilkens; G W Wilson; J A Wilson; G Wolf; S A Wotton; T R Wyatt; S Yamashita; G Yekutieli; V Zacek; D Zer-Zion

1997-01-01

335

A double pendulum plasma thrust balance and thrust measurement at a tandem mirror exhaust  

SciTech Connect

For the purpose of measuring the plasma momentum flux in a plasma system, a highly sensitive and precision balance has been developed. It can measure a force, an impulse, or thrust as low as 0.1 mN free of mechanical noise, electrical and magnetic pickups. The double pendulum system consists of two parallel conducting plates. One or both of the plates can be suspended by needles. The needle suspended plate (or plates) can swing freely with negligible friction because of the sharp points of the needles. When one of the plates is impacted by an impulse it will swing relatively to the fixed plate or other movable plate. The capacitance between the plates changes as a result of such a motion. The change of capacitance as a function of time is recorded as an oscillating voltage signal. The amplitude of such a voltage signal is proportional to the impacting force or impulse. The proportional factor can be calibrated. The forces can thus be read out from the recorded value of the voltage. The equation of motion for the pendulum system has been solved analytically. The circuit equation for the electronic measurement system has been formulated and solved numerically. Using this balance the thrust at the exhaust of a Tandem Mirror plasma thruster has been measured. The analytical solution of the overall characteristics agrees greatly with the measurement. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Yang, T.F.; Liu, P.; Chang-Diaz, F.R.; Lander, H.; Childs, R.A.; Becker, H.D.; Fairfax, S.A. [Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)] [Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

1995-09-01

336

Momentum Flux Measurements Using an Impact Thrust Stand  

NASA Technical Reports Server (NTRS)

A device has been developed to measure the force caused by a beam of charged and neutral particles impacting a target plate. This device, an impact thrust stand, was developed to allow thrusters, during early stages of development, to be quickly and easily exhausted and compared to other thrusters. Since some thruster concepts are tested using laboratory equipment that is heavy and cumbersome, measuring the momentum flux of the particles in the plume can be much simpler than placing the entire thruster on a thrust stand. Conservation of momentum requires the momentum flux measured in the plume to be related to the thrust produced by the thruster. The impact thrust stand was designed to be placed in the plume of an electric thruster and has been tested and compared to the thrust measured from a Hall thruster placed on a pendulum thrust stand. Force measurements taken at several axial locations in the magnetic nozzle region of the Variable Specific Impulse Magnetoplasma Rocket will be presented.

Chavers, Greg; Chang-Diaz, Franklin; Breizman, Boris; Bengtson, Roger

2004-01-01

337

Thrust stand for vertically oriented electric propulsion performance evaluation  

SciTech Connect

A variation of a hanging pendulum thrust stand capable of measuring the performance of an electric thruster operating in the vertical orientation is presented. The vertical orientation of the thruster dictates that the thruster must be horizontally offset from the pendulum pivot arm, necessitating the use of a counterweight system to provide a neutrally stable system. Motion of the pendulum arm is transferred through a balance mechanism to a secondary arm on which deflection is measured. A noncontact light-based transducer is used to measure displacement of the secondary beam. The members experience very little friction, rotating on twisting torsional pivots with oscillatory motion attenuated by a passive, eddy-current damper. Displacement is calibrated using an in situ thrust calibration system. Thermal management and self-leveling systems are incorporated to mitigate thermal and mechanical drifts. Gravitational force and torsional spring constants associated with flexure pivots provide restoring moments. An analysis of the design indicates that the thrust measurement range spans roughly four decades, with the stand capable of measuring thrust up to 12 N for a 200 kg thruster and up to approximately 800 mN for a 10 kg thruster. Data obtained from calibration tests performed using a 26.8 lbm simulated thruster indicated a resolution of 1 mN on 100 mN level thrusts, while those tests conducted on a 200 lbm thruster yielded a resolution of roughly 2.5 mN at thrust levels of 0.5 N and greater.

Moeller, Trevor [University of Tennessee Space Institute, Tullahoma, Tennessee 37388 (United States); Polzin, Kurt A. [NASA, Marshall Space Flight Center, Huntsville, Alabama 35812 (United States)

2010-11-15

338

Development of A Thrust Stand to Meet LISA Mission Requirements  

NASA Technical Reports Server (NTRS)

A thrust stand has been built and tested that is capable of measuring the force-noise produced by electrostatic micro-Newton (micro-Newton) thrusters. The LISA mission's Disturbance Reduction System (DRS) requires thrusters that are capable of producing continuous thrust levels between 1-100 micro-Newton with a resolution of 0.1 micro-Newton. The stationary force-noise produced by these thrusters must not exceed 0.1 pN/4Hz in a 10 Hz bandwidth. The LISA Thrust Stand (LTS) is a torsion-balance type thrust stand designed to meet the following requirements: stationary force-noise measurements from 10(exp-4) to 1 Hz with 0.1 micro-Newton resolution, absolute thrust measurements from 1-100 micro-Newton with better than 0.1 micro-Newton resolution, and dynamic thruster response from 10(exp -4) to 10 Hz. The ITS employs a unique vertical configuration, autocollimator for angular position measurements, and electrostatic actuators that are used for dynamic pendulum control and null-mode measurements. Force-noise levels are measured indirectly by characterizing the thrust stand as a spring-mass system. The LTS was initially designed to test the indium FEEP thruster developed by the Austrian Research Center in Seibersdorf (ARCS), but can be modified for testing other thrusters of this type.

Willis, William D., III; Zakrzwski, C. M.; Bauer, Frank H. (Technical Monitor)

2002-01-01

339

Thrust stand for vertically oriented electric propulsion performance evaluation.  

PubMed

A variation of a hanging pendulum thrust stand capable of measuring the performance of an electric thruster operating in the vertical orientation is presented. The vertical orientation of the thruster dictates that the thruster must be horizontally offset from the pendulum pivot arm, necessitating the use of a counterweight system to provide a neutrally stable system. Motion of the pendulum arm is transferred through a balance mechanism to a secondary arm on which deflection is measured. A noncontact light-based transducer is used to measure displacement of the secondary beam. The members experience very little friction, rotating on twisting torsional pivots with oscillatory motion attenuated by a passive, eddy-current damper. Displacement is calibrated using an in situ thrust calibration system. Thermal management and self-leveling systems are incorporated to mitigate thermal and mechanical drifts. Gravitational force and torsional spring constants associated with flexure pivots provide restoring moments. An analysis of the design indicates that the thrust measurement range spans roughly four decades, with the stand capable of measuring thrust up to 12 N for a 200 kg thruster and up to approximately 800 mN for a 10 kg thruster. Data obtained from calibration tests performed using a 26.8 lbm simulated thruster indicated a resolution of 1 mN on 100 mN level thrusts, while those tests conducted on a 200 lbm thruster yielded a resolution of roughly 2.5 mN at thrust levels of 0.5 N and greater. PMID:21133502

Moeller, Trevor; Polzin, Kurt A

2010-11-01

340

Full Flight Envelope Direct Thrust Measurement on a Supersonic Aircraft  

NASA Technical Reports Server (NTRS)

Direct thrust measurement using strain gages offers advantages over analytically-based thrust calculation methods. For flight test applications, the direct measurement method typically uses a simpler sensor arrangement and minimal data processing compared to analytical techniques, which normally require costly engine modeling and multisensor arrangements throughout the engine. Conversely, direct thrust measurement has historically produced less than desirable accuracy because of difficulty in mounting and calibrating the strain gages and the inability to account for secondary forces that influence the thrust reading at the engine mounts. Consequently, the strain-gage technique has normally been used for simple engine arrangements and primarily in the subsonic speed range. This paper presents the results of a strain gage-based direct thrust-measurement technique developed by the NASA Dryden Flight Research Center and successfully applied to the full flight envelope of an F-15 aircraft powered by two F100-PW-229 turbofan engines. Measurements have been obtained at quasi-steady-state operating conditions at maximum non-augmented and maximum augmented power throughout the altitude range of the vehicle and to a maximum speed of Mach 2.0 and are compared against results from two analytically-based thrust calculation methods. The strain-gage installation and calibration processes are also described.

Conners, Timothy R.; Sims, Robert L.

1998-01-01

341

Sensors and Actuators A 132 (2006) 689700 Pneumatically actuated micromachined synthetic jet modulators  

E-print Network

on the demonstration of and application of one or more single-orifice synthetic jet actuators in jet vectoring results. In this work the authors present a multi-orifice synthetic jet actuator and investigate the feasibility of using integrated microvalves for dynamic orifice output modulation. A multi-orifice synthetic

342

Solution of the problem of flow of a non-axisymmetric swirling submerged jets  

NASA Astrophysics Data System (ADS)

This paper considers the problem of a non-axisymmetric swirling jet of an incompressible viscous fluid flowing in a space flooded with the same fluid. The far field of the jet is studied under the assumption that the angular momentum vector corresponding to the swirling of the jet is not collinear to the momentum vector of the jet. It is shown that the main terms of the asymptotic expansion of the full solution for the velocity field are determined by the exact integrals of conservation of momentum, mass, and angular momentum. An analytical solution of the problem describing the axisymmetric swirling jet is obtained.

Mullyadzhanov, R. I.; Yavorskii, N. I.

2013-03-01

343

Controlling pulsatile jet formation number with variable diameter exit nozzle for maximum impulse generation  

NASA Astrophysics Data System (ADS)

Both jellyfish and Squid propel themselves by ejecting high momentum vortex rings. A set of vortex ring generating thrusters were developed and tested for application in underwater vehicle propulsion. Vortex rings generated from a steady piston cylinder mechanism have a universal formation time, known as the formation number (Gharib et al. 1998), associated with reaching maximum circulation, where the vortex ring separates from its trailing shear flow. The non-dimensional jet formation time (also called the stroke ratio) plays a key role in the thrust output of the device; since thrusters operating above the formation number re-ingest the trailing jet. A variable diameter exit nozzle was used to increase the formation number of the jet to maximize thrust (which is a technique observed in squid and jellyfish locomotion). Visualization studies confirmed the ability to delay the onset of ring ``pinch-off'', using a variable nozzle, and the thrust was empirically shown to achieve a higher maximum. Additionally, a fluid slug model which was developed to predict the thrust output was adapted to incorporate a changing nozzle diameter. This model was verified with the empirical thrust data and was again shown to be accurate for stroke ratios below the formation number.

Krieg, Mike; Thomas, Tyler; Mohseni, Kamran

2009-11-01

344

Thermal Effects on Inverted Pendulum Thrust Stands for Steady-state High-power Plasma Thrusters  

E-print Network

Thermal Effects on Inverted Pendulum Thrust Stands for Steady-state High-power Plasma Thrusters A-power ( 10s of kWs) plasma thrusters using inverted-pendulum thrust stands are addressed. Three major sources of system- atic error exist in the determination of thrust using an inverted-pendulum thrust stand; tare

Choueiri, Edgar

345

PALEOMAGNETIC STUDY OF THRUST SHEET ROTATION DURING FORELAND IMPINGEMENT IN THE WYOMING-IDAHO OVERTHRUST BELT  

Microsoft Academic Search

Upper Jurassic and Lower Cretaceous strata in the Darby and Absaroka thrust sheets were sampled in order to paleomagnetically evaluate thrust sheet rotation in the Wyoming-Idaho overthrust belt. No significant rotations were found. Lack of rotation in these thrust sheets suggests that previously reported rotation of the Prospect thrust sheet was not transmit- ted to the older Darby and Absaroka

Susan Y. Schwartz; Rob Van der Voo

1984-01-01

346

Cold-flow acoustic evaluation of a small scale, divergent, lobed nozzle for supersonic jet noise suppression  

NASA Technical Reports Server (NTRS)

A supersonic jet noise suppressor was tested with cold flow for acoustic and thrust characteristics at nozzle- to atmospheric-pressure ratios of 1.5 to 4.0. Jet noise suppression and spectral characteristics of the divergent, lobed, suppressor (DLS) nozzle with and without an ejector are presented. Suppression was obtained at nozzle pressure ratios of 2.5 to 4.0. The largest, maximum-lobe, sound pressure level suppression with a hard-wall ejector was 14.6 decibels at a nozzle pressure ratio of 3.5. The thrust loss was 2 percent. In general, low-frequency jet noise was suppressed, leaving higher frequencies essentially unchanged. Without the ejector the nozzle showed a thrust loss of 11 percent together with slightly poorer noise suppression.

Huff, R. G.; Groesbeck, D. E.

1975-01-01

347

Spreading Characteristics of Compressible Jets from Nozzles of Various Geometries  

NASA Technical Reports Server (NTRS)

The spreading characteristics of jets from several asymmetric nozzles, and a set of rectangular orifices are compared, covering a jet Mach number range of 0.3-2.0. The effect of 'tabs' for a rectangular and a round nozzle is also included in the comparison. Compared to a round jet, the jets from the asymmetric nozzles spread only slightly more at subsonic conditions whereas at supersonic conditions, when 'screech' occurs, they spread much more. The dynamics of the azimuthal vortical structures of the jet, organized and intensified under the screeching condition, are thought to be responsible for the observed effect at supersonic conditions. Curiously, the jet from a 'lobed' nozzle spreads much less at supersonic condition compared to all other cases; this is due to the absence of screech with this nozzle. Screech stages inducing flapping, rather than varicose or helical, flow oscillation cause a more pronounced jet spreading. At subsonic conditions, only a slight increase in jet spreading with the asymmetric nozzles contrasts previous observations by others. The present results show that the spreading of most asymmetric jets is not much different from that of a round jet. This inference is further supported by data from the rectangular orifices. In fact, jets from the orifices with small aspect ratio (AR) exhibit virtually no increase in the spreading. A noticeable increase commences only when AR is larger than about 10. Thus, 'shear layer perimeter stretching', achieved with a larger AR for a given cross-sectional area of the orifice, by itself, proves to be a relatively inefficient mechanism for increasing jet spreading. In contrast, the presence of streamwise vortices or 'natural excitation' can cause a significant increase - effects that might explain the observations in the previous investigations. Thus far, the biggest increase in jet spreading is observed with the tabs. This is true in the subsonic regime, as well as in the supersonic regime, in spite of the fact that screech is eliminated by the tabs. The characteristic spreading of the tabbed jets is explained by the induced motion of the tab-generated streamwise vortex pairs. The tabs, however, incur thrust loss; the flow blockage and loss in thrust coefficient, vis-a-vis the spreading increase, are evaluated for various configurations.

Zaman, K. B. M. Q.

1999-01-01

348

Quaternary blind thrusting in the southwestern Sacramento Valley, California  

NASA Astrophysics Data System (ADS)

Patterns of microearthquakes and Quaternary surface deformation suggest that the tectonic setting of the SW Sacramento Valley is similar to areas of the western San Joaquin Valley known to be underlain by seismogenic blind thrust faults. On the basis of previous work and analysis of geologic and seismic reflection data, the following late Cenozoic tectonic features and processes are identified: (1) uplift of the northern Coast Ranges beginning approximately 3.4 Ma, and eastward propagation of uplift into the southwestern Sacramento Valley by 1.0 Ma; (2) uplift and homoclinal flexure of Plio-Pleistocene strata at the eastern Coast Ranges mountain front; (3) uplift and folding above blind thrusts approximately 15 km east of the mountain front in the southwestern Sacramento Valley. Similar associations of structures and processes have been observed in thrust belts in Pakistan, the Peruvian Andes, and the Canadian Cordillera and are commonly attributed to thrusting within an intercutaneous wedge or triangle zone. By using other thrust belts as analogs, the propagation of an eastward tapering triangle zone is interpreted to be the principal mechanism for uplift and homoclinal flexure at the eastern Coast Ranges mountain front. Seismic reflection profiles reveal that (1) the triangle zone consists primarily of east-vergent blind thrusts and (2) west-vergent backthrusts exposed in the the eastern Coast Ranges and southwestern Sacramento Valley are rooted in the east-vergent thrusts. Transfer of slip from the east-vergent blind thrusts to the west-vergent backthrusts occurs locally beneath the southwestern Sacramento Valley. Fault-bend folding in the hanging walls of the backthrusts has created a north-northwest striking chain of low hills approximately 15 km east of the mountain front. The folds deform 3.4-1.0 Ma fluvial sediments and thus are middle Pleistocene in age or younger. Local variations in strike suggest that the fold chain is segmented, like the New Idria-Coalinga-Kettleman Hills segmented fold chain in the southwestern San Joaquin Valley (Stein and Ekström, 1989). These data have implications for seismic hazard assessment. Anecdotal accounts indicate that two M = 6.0+ events of the 1892 Winters-Vacaville earthquake sequence probably occurred beneath the eastern Coast Ranges (Dale, 1977; Toppozada et al., 1981). Ground cracking was observed following the main shocks along the mountain front in the southwestern Sacramento Valley. We propose that the earthquakes were generated by slip on a blind thrust beneath the Coast Ranges, and that the ground cracking in the valley represents propagation of the eastward tapering triangle zone. The 1892 earthquake sequence suggests that blind thrusts beneath the southwestern Sacramento Valley are active and capable of generating moderate to large magnitude earthquakes.

Unruh, J. R.; Moores, E. M.

1992-04-01

349

Strain path partitioning within thrust sheets: microstructural and petrofabric evidence from the Moine Thrust zone at Loch Eriboll, northwest Scotland  

NASA Astrophysics Data System (ADS)

Quartz c axis fabrics and microstructures have been investigated within a suite of quartzites collected from the Loch Eriboll area of the Moine Thrust zone and are used to interpret the detailed processes involved in fabric evolution. The intensity of quartz c axis fabrics is directly proportional to the calculated strain magnitude. A correlation is also established between the pattern of c axis fabrics and the calculated strain symmetry. Two kinematic domains are recognized within one of the studied thrust sheets which outcrops immediately beneath the Moine Thrust. Within the upper and central levels of the thrust sheet coaxial deformation is indicated by conjugate, mutually interfering shear bands, globular low strain detrital quartz grains whose c axes are aligned sub-parallel to the principal finite shortening direction ( Z) and quartz c axis fabrics which are symmetric (both in terms of skeletal outline and intensity distribution) with respect to mylonitic foliation and lineation. Non-coaxial deformation is indicated within the more intensely deformed and recrystallized quartzites located near the base of the thrust sheet by single sets of shear bands and c axis fabrics which are asymmetric with respect to foliation and lineation. Tectonic models offering possible explanations for the presence of kinematic (strain path) domains within thrust sheets are considered.

Law, R. D.; Knipe, R. J.; Dayan, H.

350

Operating limitations of high speed jet lubricated ball bearings  

NASA Technical Reports Server (NTRS)

A parametric study was performed with 120-mm bore angular-contact ball bearings having a nominal contact angle of 20 degrees. The bearings had either an inner- or an outer-race land riding cage, and lubrication was by recirculating oil jets which had either a single or dual orifice. Thrust load, speed, and lubricant flow rate were varied. Test results were compared with those previously reported and obtained from bearings of the same design which were under-race lubricated but run under the same conditions. Jet lubricated ball bearings were limited to speeds less than 2,500,000 DN, and bearings having inner-race land riding cages produced lower temperatures than bearings with outer-race land riding cages. For a given lubricant flow rate dual orifice jets produced lower bearing temperatures than single orifice jets, but under-race lubrication produced lower bearing temperatures under all conditions of operation with no apparent bearing speed limitation.

Zaretsky, E. V.; Signer, H.; Bamberger, E. N.

1975-01-01

351

Haar LBP Gabor Jet boosting Gabor Jet  

E-print Network

Boosting 1 boosting Haar LBP Gabor Jet boosting LBP Haar Gabor Jet boosting TP391. Further more, three kinds of local feature, Haar like feature, LBP histogram and Gabor jet are extracted, Haar like feature is more efficient for discriminating young and middle aged people, and Gabor Jet fits

Ai, Haizhou

352

Jet Shapes and Jet Algorithms in SCET  

E-print Network

Jet shapes are weighted sums over the four-momenta of the constituents of a jet and reveal details of its internal structure, potentially allowing discrimination of its partonic origin. In this work we make predictions for quark and gluon jet shape distributions in N-jet final states in e+e- collisions, defined with a cone or recombination algorithm, where we measure some jet shape observable on a subset of these jets. Using the framework of Soft-Collinear Effective Theory, we prove a factorization theorem for jet shape distributions and demonstrate the consistent renormalization-group running of the functions in the factorization theorem for any number of measured and unmeasured jets, any number of quark and gluon jets, and any angular size R of the jets, as long as R is much smaller than the angular separation between jets. We calculate the jet and soft functions for angularity jet shapes \\tau_a to one-loop order (O(alpha_s)) and resum a subset of the large logarithms of \\tau_a needed for next-to-leading logarithmic (NLL) accuracy for both cone and kT-type jets. We compare our predictions for the resummed \\tau_a distribution of a quark or a gluon jet produced in a 3-jet final state in e+e- annihilation to the output of a Monte Carlo event generator and find that the dependence on a and R is very similar.

Stephen D. Ellis; Andrew Hornig; Christopher Lee; Christopher K. Vermilion; Jonathan R. Walsh

2010-11-15

353

Effects of Nozzle Geometries on Thrust Performance Improvement of Micro-Multi-Nozzle-Array Thrusters  

Microsoft Academic Search

Microfabrication of a 3 x 3 micro-plasmajet array with ultra-violet lasers and their thrust performance tests were conducted for nozzle elements with exit height of 0.5 mm and length of 1 mm. To evaluate the thrust characteristics of the nozzle-array, its thrust performance was compared with a single-nozzle. The thrust was measured by a calibrated cantilever-type thrust stand in vacuum.

Fujimi Sawada; Atsushi Koshiyama; Shuji Hagiwara; Hideyuki Horisawa; Ikkoh Funaki

2009-01-01

354

Piloted Simulation Study of a Dual Thrust-Cutback Procedure for Reducing High-Speed Civil Transport Takeoff Noise Levels  

NASA Technical Reports Server (NTRS)

A piloted simulation study was performed for the purpose of indicating the noise reduction benefits and piloting performance that could occur for a typical 4-engine high-Speed Civil Transport (HSCT) configuration during takeoff when a dual thrust-cutback procedure was employed with throttle operation under direct computer control. Two thrust cutbacks were employed with the first cutback performed while the vehicle was accelerating on the run-way and the second cutback performed at a distance farther downrange. Added vehicle performance improvements included the incorporation of high-lift increments into the aerodynamic database of the vehicle and the use of limited engine oversizing. Four single-stream turbine bypass engines that had no noise suppression of any kind were used with this configuration. This approach permitted establishing the additional noise suppression level that was needed to meet Federal Air Regulation Part 36 Stage 3 noise levels for subsonic commercial jet aircraft. Noise level results were calculated with the jet mixing and shock noise modules of the Aircraft Noise Prediction Program (ANOPP).

Riley, Donald R.; Glaab, Louis J.; Brandon, Jay M.; Person, Lee H., Jr.; Glaab, Patricia C.

1999-01-01

355

Geologic mapping delineates new thrust sheets, duplex structures, and timing relationships between the Meade and Crawford thrusts in Wyoming, Idaho, and Utah  

SciTech Connect

New geologic maps of nine complete and six partial 7.5[prime] quadrangles delineate a large-scale duplex comprised of at least five thrust sheets that together form the Sheep Creek culmination in the footwall of the Meade thrust. From west to east, the Sheep Creek culmination includes the Home Canyon, Sheep Creek, Red Mountain, northern Crawford, and Afton thrust sheets. The thrusts are floored by the regional sole decollement in the Cambrian Gros Ventre Formation and merge upward with a roof thrust that lies along the Meade thrust in the west and decollements in the Jurassic Gypsum Spring and Preuss salt intervals in the east. The individual thrusts of Sheep Creek culmination are generally blind thrusts that are recognized by integrating the surface mapping with subsurface well and seismic data in balanced cross sections. The common map expression for individual thrust sheets is marked by translated fault-propagation anticlines in upper Paleozoic, Triassic, and lower Jurassic rocks that are bordered to the east by frontal decollement fold trains in middle and upper Jurassic rocks. The Meade thrust is folded above the Sheep Creek culmination in the northern part of the map area, and it is specifically folded above the Crawford fault-propagation fold, Sublette anticline, north of the map area at Elk Valley, Idaho. Thus, the Meade and Crawford thrusts are not coeval, linked thrusts as previously assumed. Instead, the individual thrusts of Sheep Creek culmination form a linked, eastward-younging thrust system along which 30 km of Crawford thrust displacement in Utah is partitioned between the Sheep Creek, Red Mountain, northern Crawford, and Afton thrusts in Idaho and Wyoming.

Coogan, J.C.

1993-04-01

356

Multiple Mode Actuation of a Turbulent Jet  

NASA Technical Reports Server (NTRS)

The effects of multiple mode periodic excitation on the evolution of a circular turbulent jet were studied experimentally. A short, wide-angle diffuser was attached to the jet exit. Streamwise and cross-stream excitations were introduced at the junction between the jet exit and the diffuser inlet on opposing sides of the jet. The introduction of high amplitude, periodic excitation in the streamwise direction enhances the mixing and promotes attachment of the jet shear-layer to the diffuser wall. Cross-stream excitation applied over a fraction of the jet circumference can deflect the jet away from the excitation slot. The two modes of excitation were combined using identical frequencies and varying the relative phase between the two actuators in search of an optimal response. It is shown that, for low and moderate periodic momentum input levels, the jet deflection angles depend strongly on the relative phase between the two actuators. Optimum performance is achieved when the phase difference is pi +/- pi/6. The lower effectiveness of the equal phase excitation is attributed to the generation of an azimuthally symmetric mode that does not produce the required non-axisymmetric vectoring. For high excitation levels, identical phase becomes more effective, while phase sensitivity decreases. An important finding was that with proper phase tuning, two unsteady actuators can be combined to obtain a non-linear response greater than the superposition of the individual effects.

Pack, LaTunia G.; Seifert, Avi

2001-01-01

357

A guidance and navigation system for continuous low-thrust vehicles. M.S. Thesis  

NASA Technical Reports Server (NTRS)

A midcourse guidance and navigation system for continuous low thrust vehicles was developed. The equinoctial elements are the state variables. Uncertainties are modelled statistically by random vector and stochastic processes. The motion of the vehicle and the measurements are described by nonlinear stochastic differential and difference equations respectively. A minimum time trajectory is defined; equations of motion and measurements are linearized about this trajectory. An exponential cost criterion is constructed and a linear feedback quidance law is derived. An extended Kalman filter is used for state estimation. A short mission using this system is simulated. It is indicated that this system is efficient for short missions, but longer missions require accurate trajectory and ground based measurements.

Jack-Chingtse, C.

1973-01-01

358

Turbulent Jets?  

NASA Astrophysics Data System (ADS)

Over the last few years we have fielded numerous supersonic jet experiments on the NOVA and OMEGA lasers and Sandia's pulsed-power Z-machine in a collaboration between Los Alamos National Laboratory, the Atomic Weapons Establishment, Lawrence Livermore National Laboratory, and Sandia National Laboratory. These experiments are being conducted to help validate our radiation-hydrodynamic codes, especially the newly developing ASC codes. One of the outstanding questions is whether these types of jets should turn turbulent given their high Reynolds number. Recently we have modified our experiments to have more Kelvin-Helmholtz shear, run much later in time and therefore have a better chance of going turbulent. In order to diagnose these large (several mm) jets at very late times ( 1000 ns) we are developing point-projection imaging on both the OMEGA laser, the Sandia Z-Machine, and ultimately at NIF. Since these jets have similar Euler numbers to jets theorized to be produced in supernovae explosions, we are also collaborating with the astrophysics community to help in the validation of their new codes. This poster will present a review of the laser and pulsed-power experiments and a comparison of the data to simulations by the codes from the various laboratories. We will show results of simulations wherein these jets turn highly 3-dimensional and show characteristics of turbulence. With the new data, we hope to be able to validate the sub-grid-scale turbulent mix models (e. g. BHR) that are being incorporated into our codes.*This work is performed under the auspices of the U. S. Department of Energy by the Los Alamos National Laboratory Laboratory under Contract No. W-7405-ENG-36, Lawrence Livermore National Laboratory under Contract No. W-7405-ENG-48, the Laboratory for Laser Energetics under Contract No. DE-FC03-92SF19460, Sandia National Laboratories under Contract No. DE-AC04-94AL85000, the Office of Naval Research, and the NASA Astrophysical Theory Grant.

Wilde, B. H.; Rosen, P. A.; Foster, J. M.; Perry, T. S.; Steinkamp, M. J.; Robey, H. F.; Khokhlov, A. M.; Gittings, M. L.; Coker, R. F.; Keiter, P. A.; Knauer, J. P.; Drake, R. P.; Remington, B. A.; Bennett, G. R.; Sinars, D. B.; Campbell, R. B.; Mehlhorn, T. A.

2003-10-01

359

New Research Project For The Next Nankai Trough Mega Thrust Earthquakes Towards To Understanding The Next Mega Thrust Earthquakes. And Mitigation Damages  

Microsoft Academic Search

In the Nankai trough, mega thrust earthquakes are occurring with an interval of 100-200 years. So, many researches are focusing on the Nankai trough to elucidate the recurrence system of mega thrust earthquakes. The recent result of recurrence cycle simulation indicates the difference patterns and intervals of mega- thrust earthquake recurrences in each cycle. However, these results are not satisfied

Y. Kaneda; K. Hirahara; T. Furumura

2008-01-01

360

Study of Jet-Propulsion System Comprising Blower, Burner, and Nozzle  

NASA Technical Reports Server (NTRS)

A study was made of the performance of a jet-propulsion system composed of an engine-driven blower, a combustion chamber, and a discharge nozzle. A simplified analysis is made of this system for the purpose of showing in concise form the effect of the important design variables and operating conditions on jet thrust, thrust horsepower, and fuel consumption. Curves are presented that permit a rapid evaluation of the performance of this system for a range of operating conditions. The performance for an illustrative case of a power plant of the type under consideration id discussed in detail. It is shown that for a given airplane velocity the jet thrust horsepower depends mainly on the blower power and the amount of fuel burned in the jet; the higher the thrust horsepower is for a given blower power, the higher the fuel consumption per thrust horsepower. Within limits the amount of air pumped has only a secondary effect on the thrust horsepower and efficiency. A lower limit on air flow for a given fuel flow occurs where the combustion-chamber temperature becomes excessive on the basis of the strength of the structure. As the air-flow rate is increased, an upper limit is reached where, for a given blower power, fuel-flow rate, and combustion-chamber size, further increase in air flow causes a decrease in power and efficiency. This decrease in power is caused by excessive velocity through the combustion chamber, attended by an excessive pressure drop caused by momentum changes occurring during combustion.

Hall, Eldon W

1944-01-01

361

Simple control laws for low-thrust orbit transfers  

NASA Technical Reports Server (NTRS)

Two methods are presented by which to determine both a thrust direction and when to apply thrust to effect specified changes in any of the orbit elements except for true anomaly, which is assumed free. The central body is assumed to be a point mass, and the initial and final orbits are assumed closed. Thrust, when on, is of a constant value, and specific impulse is constant. The thrust profiles derived from the two methods are not propellant-optimal, but are based firstly on the optimal thrust directions and location on the osculating orbit for changing each of the orbit elements and secondly on the desired changes in the orbit elements. Two examples of transfers are presented, one in semimajor axis and inclination, and one in semimajor axis and eccentricity. The latter compares favourably with a propellant-optimized transfer between the same orbits. The control laws have few input parameters, but can still capture the complexity of a wide variety of orbit transfers.

Petropoulos, Anastassios E.

2003-01-01

362

Demand thrust pumped propulsion with automatic warm gas valving  

NASA Astrophysics Data System (ADS)

Operation of a thrust-on-demand, monopropellant rocket propulsion system which uses lightweight low-pressure tankage, free-piston pumps, and a small high-pressure thrust chamber, is explained. The pump intake-exhaust valves use warm gas pneumatic signals to ensure that two reciprocating pumps are alternately pressurized, with overlap during switchover to permit uninterrupted propellant flow. Experiments demonstrate that the miniature pumps operate at any speed depending on downstream demand, and can deliver nearly their own mass in hydrazine per second, at 7 MPa (1000 psi). The valves, which use the alternating layers of metal and graphite to mitigate the effects of differential thermal expansion, have been warm-gas tested for thousands of cycles. For biopropellant operation, a pair of reciprocating oxidizer pumps would be slaved to the fuel pumps' pneumatic oscillator, to provide for pulsed or continuous demand-driven flow of both liquids. Mass ratios and thrust-to-weight ratios of demand-thrust pumped propulsion systems compare quite favorably to those of pressure-fed and turbo-pumped systems. Due to the relatively high densities of storable propellants, liquid mass fractions greater than 0.95 are attainable with these novel pumps, with thrust/weight ratios above 10. The high performance potential of small propulsion systems which use reciprocating pumps suggests that this technology can significantly increase the capability of many types of small spacecraft.

Whitehead, J. C.

1992-06-01

363

Thrust Augmentation Measurements for a Pulse Detonation Engine Driven Ejector  

NASA Technical Reports Server (NTRS)

Thrust augmentation results of an ongoing study of pulse detonation engine driven ejectors are presented and discussed. The experiments were conducted using a pulse detonation engine (PDE) setup with various ejector configurations. The PDE used in these experiments utilizes ethylene (C2H4) as the fuel, and an equi-molar mixture of oxygen and nitrogen as the oxidizer at an equivalence ratio of one. High fidelity thrust measurements were made using an integrated spring damper system. The baseline thrust of the PDE engine was first measured and agrees with experimental and modeling results found in the literature. Thrust augmentation measurements were then made for constant diameter ejectors. The parameter space for the study included ejector length, PDE tube exit to ejector tube inlet overlap distance, and straight versus rounded ejector inlets. The relationship between the thrust augmentation results and various physical phenomena is described. To further understand the flow dynamics, shadow graph images of the exiting shock wave front from the PDE were also made. For the studied parameter space, the results showed a maximum augmentation of 40%. Further increase in augmentation is possible if the geometry of the ejector is tailored, a topic currently studied by numerous groups in the field.

Pal, S.; Santoro, Robert J.; Shehadeh, R.; Saretto, S.; Lee, S.-Y.

2005-01-01

364

Grenville foreland thrust belt hidden beneath the eastern US midcontinent  

SciTech Connect

Grenville foreland thrust structures are observed beneath the eastern US midcontinent on COCORP (Consortium for Continental Reflection Profiling) line OH-1 and a short seismic line in southwest Ohio. These structures represent the first evidence for a significant Grenville foreland thrust belt preserved in eastern North America. On the COCORP lines, the structures include a thrust ramp anticline and an associated asymmetric syncline. The Grenville front tectonic zone appears to truncate these foreland structures, indicating a later, second phase expressed as a deeply penetrating, out-of-sequence thrust zone associated with the main uplift of the Grenville province on the east. A short, shallow seismic line in southwestern Ohio reveals an east-dipping sequence of prominently layered rocks that may lie above a footwall ramp to a deeper Grenville thrust fault. A drill hole into the less reflective top of this dipping sequence encountered unmetamorphosed sedimentary rocks like those increasingly reported from other drill holes in southwestern Ohio and adjacent states. Although possibly part of a late Precambrian (Keweenawan ) rift, these clastic sedimentary rocks may instead preserve evidence of a heretofore unrecognized Grenville foreland basin in eastern North America. Alternatively these Precambrian sedimentary rocks together with an underlying, but yet undrilled, strongly layered sequence may correlate with similarly layered rocks observed on COCORP and industrial seismic lines within the Middle Proterozoic granite-rhyolite province to the west in Indiana and Illinois and indicate that unmetamorphosed sedimentary material is an important constituent of the granite-rhyolite province. 25 refs., 6 figs.

Hauser, E.C. (Cornell Univ., Ithaca, NY (United States))

1993-01-01

365

DICHOTOMY OF SOLAR CORONAL JETS: STANDARD JETS AND BLOWOUT JETS  

SciTech Connect

By examining many X-ray jets in Hinode/X-Ray Telescope coronal X-ray movies of the polar coronal holes, we found that there is a dichotomy of polar X-ray jets. About two thirds fit the standard reconnection picture for coronal jets, and about one third are another type. We present observations indicating that the non-standard jets are counterparts of erupting-loop H{alpha} macrospicules, jets in which the jet-base magnetic arch undergoes a miniature version of the blowout eruptions that produce major coronal mass ejections. From the coronal X-ray movies we present in detail two typical standard X-ray jets and two typical blowout X-ray jets that were also caught in He II 304 A snapshots from STEREO/EUVI. The distinguishing features of blowout X-ray jets are (1) X-ray brightening inside the base arch in addition to the outside bright point that standard jets have, (2) blowout eruption of the base arch's core field, often carrying a filament of cool (T {approx} 10{sup 4} - 10{sup 5} K) plasma, and (3) an extra jet-spire strand rooted close to the bright point. We present cartoons showing how reconnection during blowout eruption of the base arch could produce the observed features of blowout X-ray jets. We infer that (1) the standard-jet/blowout-jet dichotomy of coronal jets results from the dichotomy of base arches that do not have and base arches that do have enough shear and twist to erupt open, and (2) there is a large class of spicules that are standard jets and a comparably large class of spicules that are blowout jets.

Moore, Ronald L.; Cirtain, Jonathan W.; Sterling, Alphonse C.; Falconer, David A., E-mail: ron.moore@nasa.go [Space Science Office, VP62, Marshall Space Flight Center, Huntsville, AL 35812 (United States)

2010-09-01

366

Dichotomy of Solar Coronal Jets: Standard Jets and Blowout Jets  

NASA Technical Reports Server (NTRS)

By examining many X-ray jets in Hinode/XRT coronal X-ray movies of the polar coronal holes, we found that there is a dichotomy of polar X-ray jets. About two thirds fit the standard reconnection picture for coronal jets, and about one third are another type. We present observations indicating that the non-standard jets are counterparts of erupting-loop H alpha macrospicules, jets in which the jet-base magnetic arch undergoes a miniature version of the blowout eruptions that produce major CMEs. From the coronal X-ray movies we present in detail two typical standard X-ray jets and two typical blowout X-ray jets that were also caught in He II 304 Angstrom snapshots from STEREO/EUVI. The distinguishing features of blowout X-ray jets are (1) X-ray brightening inside the base arch in addition to the outside bright point that standard jets have, (2) blowout eruption of the base arch's core field, often carrying a filament of cool (T 10(exp 4) - 10(exp 5) K) plasma, and (3) an extra jet-spire strand rooted close to the bright point. We present cartoons showing how reconnection during blowout eruption of the base arch could produce the observed features of blowout X-ray jets. We infer that (1) the standard-jet/blowout-jet dichotomy of coronal jets results from the dichotomy of base arches that do not have and base arches that do have enough shear and twist to erupt open, and (2) there is a large class of spicules that are standard jets and a comparably large class of spicules that are blowout jets.

Moore, R. L.; Cirtain, J. W.; Sterling, A. C.; Falconer, D. A.

2010-01-01

367

Mean streamwise velocity measurements in a triple jet of equilateral triangular configuration  

SciTech Connect

Multijet flows arise in several applications such as jet engine/rocket combustors, the thrust augmenting ejectors for VTOL/STOL aircraft, and industrial gas burners. In order to achieve proper combustion, thrust development, and reduction in the noise level, it is often desirable to control the inter-mixing between the jets and also the entrainment of the surrounding atmosphere. This, in turn, requires a detailed study of the behavior of high speed jets in multijet configuration. The situation of interest here is an array of three axisymmetric nozzles set in a common end wall with equal spacing in a triangular configuration. The reason why this particular configuration has been chosen is that it promotes bending of the jet axes toward each other, thus leading to greater mixing. In the present study, experiments have been conducted to investigate the effect of stagnation pressure ratio and nozzle spacing upon the mean flow characteristic of compressible jets in triangular configuration. The individual flow features of the vertex jet and the base twin jet are analyzed and their contributions to the axis switching as well as the overall triple jet behavior are highlighted.

Moustafa, G.H. (Menoufia Univ. (Egypt). Coll. of Engineering); Sundararajan, T. (IIT Kanpur (India). Dept. of Mechanical Engineering); Rathakrishnan, E. (IIT Kanpur (India). Dept. of Aerospace Engineering)

1993-09-01

368

Marine Jet  

NASA Technical Reports Server (NTRS)

The marine turbine pump pictured is the Jacuzzi 12YJ, a jet propulsion system for pleasure or commercial boating. Its development was aided by a NASA computer program made available by the Computer Software Management and Information Center (COSMIC) at the University of Georgia. The manufacturer, Jacuzzi Brothers, Incorporated, Little Rock, Arkansas, used COSMIC'S Computer Program for Predicting Turbopump Inducer Loading, which enabled substantial savings in development time and money through reduction of repetitive testing.

1978-01-01

369

Jets from compact objects  

E-print Network

Some topics in the theory of jets are reviewed. These include jet precession, unconfined jets, the origin of knots, the internal shock model as a unifying theme from protostellar jets to Gamma-ray bursts, relations between the Blandford-Znajek and MHD disk-wind models, and jet collimation in magnetic acceleration models.

H. C. Spruit

2000-03-03

370

Control of a Thrust Alignment Table for Modeling the Coning Dynamics of a Spinning Spacecraft with a Follower Force  

NASA Technical Reports Server (NTRS)

This document presents a system controlling the motion of a spherical air bearing used in the modeling of spacecraft dynamics and controls in a laboratory environment. The system is part of the Spinning Rocket Simulator (SRS), used to simulate the coning of spacecraft during a thrusting stage. The reaction force at the spherical air bearing supporting the spacecraft model must coincide with the thrust axis of the model for proper simulation. Therefore, the bearing is translated in a circular path to introduce a centrifugal force. This horizontal force along with the gravitational reaction force at the bearing combines to simulate the direction of the spacecraft's thrust force. The control system receives attitude information from the spacecraft model via a laser beam embedded in the model that impinges on a photosensitive array. The non-linear system is controlled using high-speed lookup tables and digital techniques. A vector-controlled motor and a stepper motor are given the necessary signals to accurately control the turntable and platform supporting the air bearing. Preliminary performance data is presented. Mechanical elements of the table and platform are described in detail. A wireless (RF) data path for all devices on the spacecraft model to an off-table command computer is also described.

Halsmer, Dominic; Bennett, J. Damon; DeHaven, Max; Ligard, Vidar

1999-01-01

371

Demand thrust pumped propulsion with automatic warm gas valving  

NASA Astrophysics Data System (ADS)

A thrust-on-demand, monopropellant rocket propulsion system is described which is based on lightweight low-pressure tankage, free-piston pumps, and a small high-pressure thrust chamber. This tightly-packaged automatic valving design enables pairs of warm-gas-driven reciprocating pumps to deliver storable propellants on demand, at any rate up to the pumps' own mass per second at 7 MPa. The objective of the technology under consideration is to make pumped propellant performance available to spacecraft which must thrust on demand, while retaining the characteristic high mass ratios of pumped systems and minimizing associated complexity. This technology makes it possible to increase the useful payload and enhance safety due to the lower tankage pressures by decreasing the size of satellite propulsion system. The shutdown capability offers possibilities for orbital maneuvering scenarios.

Whitehead, John C.

1992-07-01

372

Full-scale thrust reverser testing in an altitude facility  

NASA Technical Reports Server (NTRS)

A two-dimensional convergent-divergent exhaust nozzle designed and fabricated by Pratt and Whitney Aircraft was installed on a PW1128 turbofan engine and tested during thrust reverser operation in an altitude facility at NASA Lewis Research Center. A unique collection system was used to capture the thrust reverser exhaust gas and transport it to the primary exhaust collector. Tests were conducted at three flight conditions with varying amounts of thrust reverse at each condition. Some reverser exhaust gas spillage by the collection system was encountered but engine performance was unaffected at all flight conditions tested. Based on the results of this test program, the feasibility of altitude testing of advanced multi-function exhaust nozzle systems has been demonstrated.

Mehalic, Charles M.; Lottig, Roy A.

1987-01-01

373

Numerical grid generation and flow simulation in SSME thrust chamber  

SciTech Connect

The development of liquid and solid rocket engines for future space projects demands a detailed optimization process for highly efficient performance and cost reasons. Also, testing of full size engines may not be feasible when the large size requires test facilities which are cost prohibitive or if vacuum operation cannot be acquired. For such situations only scaling from small test scale measurements or accurate analytical predictions will provide the performance prior to actually flying the mission. A rigorous approach for simulating the combustion processes in liquid rocket engines by employing a direct solution of Navier-Stokes equations within the entire volume of the thrust chambers is presented. This method is illustrated in the solution of reactive flow in the Space Shuttle Main Engine (SSME) thrust chamber. The objective is to review recent improvements in the mathematical model and to present the grid generation methodology suitable for rocket thrust chamber geometries.

Gross, K.W.; Daley, P.L.; Przekwas, A.J.

1987-01-01

374

Viscoplastic analysis of an experimental cylindrical thrust chamber liner  

NASA Technical Reports Server (NTRS)

A viscoplastic stress-strain analysis of an experimental cylindrical thrust chamber is presented. A viscoelastic constitutive model incorporating a single internal state variable that represents kinematic hardening was employed to investigate whether such a viscoplastic model could predict the experimentally observed behavior of the thrust chamber. Two types of loading cycles were considered: a short cycle of 3.5-s duration that corresponded to the experiments, and an extended loading cycle of 485.1 s duration that is typical of the Space Shuttle Main Engine (SSME) operating cycle. The analysis qualitatively replicated the deformation behavior of the component as observed in experiments designed to simulate SSME operating conditions. The analysis also showed that the mode and location of failure in the component may depend on the loading cycle. The results indicate that using viscoplastic models for structural analysis can lead to a more realistic life assessment of thrust chambers.

Arya, Vinod K.; Arnold, Steven M.

1992-01-01

375

Viscoplastic analysis of an experimental cylindrical thrust chamber liner  

NASA Technical Reports Server (NTRS)

A viscoplastic stress-strain analysis of an experimental cylindrical thrust chamber is presented. A viscoelastic constitutive model incorporating a single internal state variable that represents kinematic hardening was employed to investigate whether such a viscoplastic model could predict the experimentally observed behavior of the thrust chamber. Two types of loading cycles were considered: a short cycle of 3.5 sec. duration that corresponded to the experiments, and an extended loading cycle of 485.1 sec. duration that is typical of the Space Shuttle Main Engine (SSME) operating cycle. The analysis qualitatively replicated the deformation behavior of the component as observed in experiments designed to simulate SSME operating conditions. The analysis also showed that the mode and location in the component may depend on the loading cycle. The results indicate that using viscoplastic models for structural analysis can lead to a more realistic life assessment of thrust chambers.

Arya, Vinod K.; Arnold, Steven M.

1991-01-01

376

Hydrodynamics of pulsed jetting in juvenile and adult brief squid Lolliguncula brevis: evidence of multiple jet 'modes' and their implications for propulsive efficiency.  

PubMed

The dynamics of pulsed jetting in squids throughout ontogeny is not well understood, especially with regard to the development of vortex rings, which are common features of mechanically generated jet pulses (also known as starting jets). Studies of mechanically generated starting jets have revealed a limiting principle for vortex ring formation characterized in terms of a ;formation number' (F), which delineates the transition between the formation of isolated vortex rings and vortex rings that have; pinched off' from the generating jet. Near F, there exists an optimum in pulse-averaged thrust with (potentially) low energetic cost, raising the question: do squids produce vortex rings and if so, do they fall near F, where propulsive benefits presumably occur? To better understand vortex ring dynamics and propulsive jet efficiency throughout ontogeny, brief squid Lolliguncula brevis ranging from 3.3 to 9.1 cm dorsal mantle length (DML) and swimming at speeds of 2.43-22.2 cms(-1) (0.54-3.50 DMLs(-1)) were studied using digital particle image velocimetry (DPIV). A range of jet structures were observed but most structures could be classified as variations of two principal jet modes: (1) jet mode I, where the ejected fluid rolled up into an isolated vortex ring; and (2) jet mode II, where the ejected fluid developed into a leading vortex ring that separated or ;pinched off' from a long trailing jet. The ratio of jet length [based on the vorticity extent (L(omega))] to jet diameter [based on peak vorticity locations (D(omega))] was <3.0 for jet mode I and >3.0 for jet mode II, placing the transition between modes in rough agreement with F determined in mechanical jet studies. Jet mode II produced greater time-averaged thrust and lift forces and was the jet mode most heavily used whereas jet mode I had higher propulsive efficiency, lower slip, shorter jet periods and a higher frequency of fin activity associated with it. No relationship between L(omega)/D(omega) and speed was detected and there was no apparent speed preference for the jet modes within the speed range considered in this study; however, propulsive efficiency did increase with speed partly because of a reduction in slip and jet angle with speed. Trends in higher slip, lower propulsive efficiency and higher relative lift production were observed for squid <5.0 cm DML compared with squid >/=5.0 cm DML. While these trends were observed when jet mode I and II were equally represented among the size classes, there was also greater relative dependence on jet mode I than jet mode II for squid <5.0 cm DML when all of the available jet sequences were examined. Collectively, these results indicate that approximately 5.0 cm DML is an important ontogenetic transition for the hydrodynamics of pulsed jetting in squids. The significance of our findings is that from early juvenile through to adult life stages, L. brevis is capable of producing a diversity of vortex ring-based jet structures, ranging from efficient short pulses to high-force longer duration pulses. Given that some of these structures had L(omega)/D(omega)s near F, and F represented the delineation between the two primary jet modes observed, fluid dynamics probably played an integral role in the evolution of squid locomotive systems. When this flexibility in jet dynamics is coupled with the highly versatile fins, which are capable of producing multiple hydrodynamic modes as well, it is clear that squid have a locomotive repertoire far more complex than originally thought. PMID:19483007

Bartol, Ian K; Krueger, Paul S; Stewart, William J; Thompson, Joseph T

2009-06-01

377

Was Himalayan normal faulting triggered by initiation of the Ramgarh-Munsiari Thrust?  

USGS Publications Warehouse

The Ramgarh–Munsiari thrust is a major orogen-scale fault that extends for more than 1,500 km along strike in the Himalayan fold-thrust belt. The fault can be traced along the Himalayan arc from Himachal Pradesh, India, in the west to eastern Bhutan. The fault is located within the Lesser Himalayan tectonostratigraphic zone, and it translated Paleoproterozoic Lesser Himalayan rocks more than 100 km toward the foreland. The Ramgarh–Munsiari thrust is always located in the proximal footwall of the Main Central thrust. Northern exposures (toward the hinterland) of the thrust sheet occur in the footwall of the Main Central thrust at the base of the high Himalaya, and southern exposures (toward the foreland) occur between the Main Boundary thrust and Greater Himalayan klippen. Although the metamorphic grade of rocks within the Ramgarh–Munsiari thrust sheet is not significantly different from that of Greater Himalayan rock in the hanging wall of the overlying Main Central thrust sheet, the tectonostratigraphic origin of the two different thrust sheets is markedly different. The Ramgarh–Munsiari thrust became active in early Miocene time and acted as the roof thrust for a duplex system within Lesser Himalayan rocks. The process of slip transfer from the Main Central thrust to the Ramgarh–Munsiari thrust in early Miocene time and subsequent development of the Lesser Himalayan duplex may have played a role in triggering normal faulting along the South Tibetan Detachment system.

Robinson, Delores M.; Pearson, Ofori N.

2013-01-01

378

Receding Horizon Control of a Vectored Thrust Flight Experiment Mark B. Milam Ryan Franz  

E-print Network

, computational method developed and implemented by Milam et al., that combines nonlinear control theory, B-spline convergent stability if not implemented properly. These difficulties have largely prevented its application for a good review of recent work in this field. To implement the receding horizon control strategy

Murray, Richard M.

379

A Change of Inertia-Supporting the Thrust Vector Control of the Space Launch System  

NASA Technical Reports Server (NTRS)

The Space Launch System (SLS) is America's next launch vehicle. To utilize the vehicle more economically, heritage hardware from the Space Transportation System (STS) will be used when possible. The Solid Rocket Booster (SRB) actuators could possibly be used in the core stage of the SLS. The dynamic characteristics of the SRB actuator will need to be tested on an Inertia Load Stand (ILS) that has been converted to Space Shuttle Main Engine (SSME). The inertia on the pendulum of the ILS will need to be changed to match the SSME inertia. In this testing environment an SRB actuator can be tested with the equivalent resistence of an SSME.

Dziubanek, Adam J.

2012-01-01

380

Imaging deformation in submarine thrust belts using seismic attributes  

NASA Astrophysics Data System (ADS)

Uncertainty exists as to the patterns of deformation that develop within submarine thrust belts. This case study uses a large-scale gravity-driven fold-thrust structure as an analogue for submarine fold thrust systems in general. Seismic attribute analysis and mapping provide ways of identifying complex fault patterns and associated deformation that are otherwise unresolved in conventional amplitude displays. These methods are developed and applied to a 3D dataset and used to investigate the geometry, internal architecture and the nature of the low signal/noise incoherency and discontinuities observed on the km-scale. Semblance (coherency), curvatures and spectral decomposition were all computed and used as attributes. Collectively these define volumes within the seismic data where the signal is greatly reduced — features termed here "disturbance geobodies". The study shows that thrust faults that, on conventional amplitude displays appear to be simple and continuous, are likely to consist of complex arrays of anastamosing fault strands. Adjacent to these composite fault zones are greater volumes of deformed rocks (disturbance geobodies) across which there are only minor stratal offsets. Similarly volumes of high stratal curvature coincide with disturbance geobodies, again interpreted as zones of weak, distributed deformation. These relationships between narrow thrust faults and broader zones of deformation are broadly comparable to those observed in outcrops within exhumed thrust systems. Application of the seismic imaging techniques developed here will improve the understanding of the localization of deformation in sedimentary successions with important implications for predicting fluid flow within other deep water structures such as subduction accretion complexes.

Iacopini, David; Butler, Robert W. H.

2011-02-01

381

Particle acceleration in electron-ion jets  

E-print Network

Weibel instability created in collisionless shocks is responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic electron-ion jet fronts propagating into an ambient plasma without initial magnetic fields with a longer simulation system in order to investigate nonlinear stage of the Weibel instability and its acceleration mechanism. The current channels generated by the Weibel instability induce the radial electric fields. The z component of the Poynting vector (E x B) become positive in the large region along the jet propagation direction. This leads to the acceleration of jet electrons along the jet. In particular the E x B drift with the large scale current channel generated by the ion Weibel instability accelerate electrons effectively in both parallel and perpendicular directions.

K. -I. Nishikawa; P. Hardee; C. B. Hededal; G. Richardson; R. Preece; H. Sol; G. J. Fishman; C. Kouvelioutou; Y. Mizuno

2005-09-20

382

Problems of millipound thrust measurement. The "Hansen Suspension"  

SciTech Connect

Considered in detail are problems which led to the need and use of the 'Hansen Suspension'. Also discussed are problems which are likely to be encountered in any low level thrust measuring system. The methods of calibration and the accuracies involved are given careful attention. With all parameters optimized and calibration techniques perfected, the system was found capable of a resolution of 10 {mu} lbs. A comparison of thrust measurements made by the 'Hansen Suspension' with measurements of a less sophisticated device leads to some surprising results.

Carta, David G.

2014-03-31

383

Fabrication of liquid-rocket thrust chambers by electroforming  

NASA Technical Reports Server (NTRS)

Electroforming has proven to be an excellent fabrication method for building liquid rocket regeneratively cooled thrust chambers. NASA sponsored technology programs have investigated both common and advanced methods. Using common procedures, several cooled spool pieces and thrust chambers have been made and successfully tested. The designs were made possible through the versatility of the electroforming procedure, which is not limited to simple geometric shapes. An advanced method of electroforming was used to produce a wire-wrapped, composite, pressure-loaded electroformed structure, which greatly increased the strength of the structure while still retaining the advantages of electroforming.

Duscha, R. A.; Kazaroff, J. M.

1974-01-01

384

Accurate analytical approximation of asteroid deflection with constant tangential thrust  

NASA Astrophysics Data System (ADS)

We present analytical formulas to estimate the variation of achieved deflection for an Earth-impacting asteroid following a continuous tangential low-thrust deflection strategy. Relatively simple analytical expressions are obtained with the aid of asymptotic theory and the use of Peláez orbital elements set, an approach that is particularly suitable to the asteroid deflection problem and is not limited to small eccentricities. The accuracy of the proposed formulas is evaluated numerically showing negligible error for both early and late deflection campaigns. The results will be of aid in planning future low-thrust asteroid deflection missions.

Bombardelli, Claudio; Baù, Giulio

2012-11-01

385

Experimental investigation of leading-edge thrust at supersonic speeds  

NASA Technical Reports Server (NTRS)

Wings, designed for leading edge thrust at supersonic speeds, were investigated in the Unitary Plan Wind Tunnel at Mach numbers of 1.60, 1.80, 2.00, 2.16, and 2.36. Experimental data were obtained on a uncambered wing which had three interchangeable leading edges that varied from sharp to blunt. The leading edge thrust concept was evaluated. Results from the investigation showed that leading edge flow separation characteristics of all wings tested agree well with theoretical predictions. The experimental data showed that significant changes in wing leading edge bluntness did not affect the zero lift drag of the uncambered wings.

Wood, R. M.; Miller, D. S.

1983-01-01

386

Thrusting, halotectonics, and sedimentation in the Spanish Pyrenees  

SciTech Connect

The Spanish Pyrenees are a linked system of regional thrust sheets and intermontane basins which formed during the Tertiary collision of the European and Iberian plates. The structural evolution of the Pyrenees was controlled by Mesozoic extensional structures and evaporite-bearing strata which served as the regional decollement and produced widespread pre- to postthrusting halotectonic folds. Palinspastic restoration of Cretaceous strata from the Pyrenean realm delineates a large normal-faulted embayment in the northern Iberian margin. Thicker sediments within the bay, coupled with the southward emplacement of the Cotiella-Montsec thrust sheet, caused underlying evaporites to flow toward the basin margins, producing folds such as the Mediano anticline.

Anastasio, D.J.

1988-08-01

387

Low-thrust chemical propulsion system pump technology  

NASA Technical Reports Server (NTRS)

Candidate pump and driver systems for low thrust cargo orbit transfer vehicle engines which deliver large space structures to geosynchronous equatorial orbit and beyond are evaluated. The pumps operate to 68 atmospheres (1000 psi) discharge pressure and flowrates suited to cryogenic engines using either LOX/methane or LOX/hydrogen propellants in thrust ranges from 445 to 8900 N (100 to 2000 lb F). Analysis of the various pumps and drivers indicate that the low specific speed requirement will make high fluid efficiencies difficult to achieve. As such, multiple stages are required. In addition, all pumps require inducer stages. The most attractive main pumps are the multistage centrifugal pumps.

Sabiers, R. L.; Siebenhaar, A.

1981-01-01

388

Sinistral strike-slip dominated inclined transpression along the Pai-Khoi fold-and-thrust belt, Russian Arctic  

NASA Astrophysics Data System (ADS)

The Arctic Uralides comprise Pai-Khoi, Novaya Zemlya and the Taimyr Peninsula. Together they form a margin controlled salient in the former Baltica margin of Laurussia. This arcuate orogen forms a fundamental tectonic boundary between major hydrocarbon provinces; Timan-Pechora and Barents Sea to the southwest and west, respectively, and the South Kara Sea to the east. To understand the complex regional tectonic relationship between the Arctic Uralides and the South Kara Sea, it is essential to establish the structural and kinematic style of the various sectors of this remote orogen. This contribution focuses on the southern limb of the salient, the NW-SE trending, Pai-Khoi fold-and-thrust belt (PKFB), which links the Polar Urals with Novaya Zemlya approximately 600 km to the northwest. The PKFB comprises a highly deformed, Late Cambrian to Mississippian age, passive margin succession, with allochthonous deep-water and continental slope facies rocks thrust over a shallow-water carbonate platform succession along the Main Pai-Khoi Thrust. Deformation is interpreted to have occurred between the Late Palaeozoic and end Triassic resulting in the formation of an apparent southwesterly verging fold-and-thrust belt with an associated foreland basin. Analysis of regional scale geological maps reveals the presence of large scale en-echelon folds, together with late stage, orogen-parallel faults, indicating that the evolution of PKFB has been influenced by a component of sinistral strike-slip. Detailed field data from a transect across the largest structure in the orogen, the Main Pai-Khoi Thrust, confirms the obliquity of both planar structures and finite stretching lineations to this major allochthon bounding thrust. Subtle but consistent variations in the orientation of finite stretching directions within zones of qualitatively differing finite strain were identified. Comparison of these variations with theoretical models of inclined transpression suggests that deformation within the PKFB is consistent with a model of strike-slip dominated, inclined transpression, where ? (angle of far field displacement vector to transpression zone) is ~20° , and the inclination of the deformation zone (?) is shallowly to moderately inclined (20-50° ). Sinistral strike-slip dominated transpression along the Pai-Khoi sector the Arctic Uralides is consistent with a Carpathian/Pannonian analogue model for the evolution of the South Kara Sea and its peripheral orogen.

Curtis, Michael

2014-05-01

389

Topological constraints on imbricate thrust networks, examples from the Mountain City window, Tennessee, U.S.A  

Microsoft Academic Search

The geometry of thrust belts is best described in three dimensions as a network of linear geometric elements: trailing branch lines, where two thrusts diverge; leading branch lines, where two thrusts converge; tip lines, where thrust displacement vanishes; and cutoff lines, where a stratigraphic horizon intersects a thrust plane. There are a number of topological constraints in three dimensions on

F. A. DIEGEL

1986-01-01

390

Interim noise correlation for some OTW configurations using external jet-flow deflectors  

NASA Technical Reports Server (NTRS)

Jet flap interaction acoustic data obtained statically from a model-scale study of STOL-OTW configurations with a conical nozzle mounted above the wing and using various external deflectors to provide jet-flow attachment are correlated. The acoustic data are correlated in terms that consider the jet/flap interaction noise contributions associated primarily with fluctuating lift, trailing edge, and configuration wake noise sources. Variables considered include deflector geometry, flap setting and wing size. Finally, the configuration overall noise levels are related to static lift and thrust measurements in order to provide insight into possible acoustic/aerodynamic performance trade-off benefits.

Vonglahn, U. H.; Groesbeck, D. E.

1977-01-01

391

The Development of Jet-engine Nacelles for a High-speed Bomber Design  

NASA Technical Reports Server (NTRS)

The results of an experimental investigation made for the purpose of developing suitable jet-engine nacelle designs for a high-speed medium bomber are presented. Two types of nacelles were investigated, the first enclosing two 4000-pounds-thrust jet engines and a 65-inch-diameter landing wheel and the second enclosing a single 4000-pounds-thrust jet engine. Both types of nacelles were tested in positions underslung beneath the wing and centrally located on the wing. This report summarizes the investigation which was performed at low speed for the purpose of developing entrance and body shapes of suitable form. Included are results from the high-speed portion of the investigation on the characteristics of an underslung nacelle.

Dannenberg, Robert E

1947-01-01

392

The mixing mechanism by organised turbulence structures in a plane jet excited by a novel method  

NASA Technical Reports Server (NTRS)

The effect on a plane subsonic turbulent jet of controlled high-amplitude periodic oscillations applied to the nozzle is investigated experimentally. A variable-speed motor and a gear-cam mechanism are used to make the lips of the nozzle reciprocate in opposite directions at the desired frequency. Velocity profiles, flow visualizations, and pressure-signal traces are presented and analyzed in detail. The complex vortex processes involved in the oscillation-induced spreading and entrainment of the jet are explored, and a critical Strouhal number for vortex formation and amplification is determined. The oscillation technique is found to augment the thrust of a jet/duct-diffuser configuration by a factor of 1.20; the thrust increases with oscillation frequency up to 20 Hz and remains constant if the frequency is further increased.

Badri Narayanan, M. A.; Platzer, Max F.

1988-01-01

393

Theoretical aerodynamics of upper-surface-blowing jet-wing interaction  

NASA Technical Reports Server (NTRS)

A linear, inviscid subsonic compressible flow theory is formulated to treat the aerodynamic interaction between the wing and an inviscid upper-surface-blowing (USB) thick jet with Mach number nonuniformity. The predicted results show reasonably good agreement with some available lift and induced-drag data. It was also shown that the thin-jet-flap theory is inadequate for the USB configurations with thick jet. Additional theoretical results show that the lift and induced drag were reduced by increasing jet temperature and increased by increasing jet Mach number. Reducing jet aspect ratio, while holding jet area constant, caused reductions in lift, induced drag, and pitching moment at a given angle of attack but with a minimal change in the curve of lift coefficient against induced-drag coefficient. The jet-deflection effect was shown to be beneficial to cruise performance. The aerodynamic center was shifted forward by adding power or jet-deflection angle. Moving the jet away from the wing surface resulted in rapid changes in lift and induced drag. Reducing the wing span of a rectangular wing by half decreased the jet-circulation lift by only 24 percent at a thrust coefficient of 2.

Lan, C. E.; Campbell, J. F.

1975-01-01

394

Wind-tunnel investigation at low speeds of a model of the Kestrel (XV-6A) vectored-trust V/STOL airplane  

NASA Technical Reports Server (NTRS)

Longitudinal and lateral stability data were obtained with the model out of and in ground effect over a moving ground plane for a range of model angles of attack and sideslip at various thrust coefficients. These data were taken primarily at thrust coefficients which simulate transition speeds on the airplane between hover and 200 knots. Some data, however, represent the effect of thrust deflection at speeds up to 350 knots. Also presented are the effects of control-surface deflections and interference between the jets and free stream.

Margason, R. J.; Vogler, R. D.; Winston, M. M.

1972-01-01

395

From Jet Counting to Jet Vetoes  

E-print Network

The properties of multi-jet events impact many LHC analysis. The exclusive number of jets at hadron colliders can be described in terms of two simple patterns: staircase scaling and Poisson scaling. In photon plus jets production we can interpolate between the two patterns using simple kinematic cuts. The associated theoretical errors are well under control. Understanding such exclusive jet multiplicities significantly impacts Higgs searches and searches for supersymmetry at the LHC.

Peter Schichtel; Christoph Englert; Erik Gerwick; Tilman Plehn; Steffen Schumann

2012-06-04

396

Engineering research, development and technology thrust area report FY97  

SciTech Connect

The mission of the Engineering Research, Development, and Technology Program at Lawrence Livermore National Laboratory (LLNL) is to develop the knowledge base, process technologies, specialized equipment, tools and facilities to support current and future LLNL programs. Engineering's efforts are guided by a strategy that results in dual benefit: first, in support of Department of Energy missions, such as national security through nuclear deterrence; and second, in enhancing the collaboration with US industry and universities in pursuit of the most cost-effective engineering solutions to LLNL programs. To accomplish this mission, the Engineering Research, Development, and Technology Program has two important goals: (1) identify key technologies relevant to LLNL programs where they can establish unique competencies, and (2) conduct high-quality research and development to enhance their capabilities and establish themselves as the world leaders in these technologies. To focus engineering's efforts, technology thrust areas are identified and technical leaders are selected for each area. The thrust areas are comprised of integrated engineering activities, staffed by personnel from the nine electronics and mechanical engineering divisions, and from other LLNL organizations. This annual report, organized by thrust area, describes Engineering's activities for fiscal year 1997. The report provides timely summaries of objectives, methods, and key results from eight thrust areas: Computational Electronics and Electromagnetics; Computational Mechanics; Microtechnology; Manufacturing Technology; Materials Science and Engineering; Power Conversion Technologies; Nondestructive Evaluation; and Optical Engineering.

Langland, R T

1998-01-01

397

Columbia, Orbiter Vehicle (OV) 102, RCS engines thrusting  

NASA Technical Reports Server (NTRS)

Columbia, Orbiter Vehicle (OV) 102, reaction control system (RCS) engine thrusting and one plume fire glow. One of the thruster firings of the forward RCS is captured with an astronaut's 35mm camera. Astronauts aimed their 35mm camera through the front windows to capture various firings of several of the thrusters which control the orbiter's movements in space.

1982-01-01

398

REAR DETAIL OF RIGHT ENGINE AND WING. THRUST REVERSER REMAINS ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

REAR DETAIL OF RIGHT ENGINE AND WING. THRUST REVERSER REMAINS OPEN. MECHANICS JONI BAINE (R) AND BILL THEODORE(L) OPEN FLAP CARRIAGE ACCESS WITH AN IMPACT GUN. THEY WILL CHECK TRANSMISSION FLUID AND OIL THE JACK SCREW. AT FAR LEFT UTILITY MECHANICS BEGIN BODY POLISHING. - Greater Buffalo International Airport, Maintenance Hangar, Buffalo, Erie County, NY

399

Digital field trip to the Central Nevada Thrust Belt  

SciTech Connect

Hydrocarbon exploration in the Central Nevada Thrust Belt is still in its infancy. However, this thrust belt contains all the elements necessary for hydrocarbon accumulations: thick, organically-rich shales; reefs, regional unconformities, karst surfaces, porous sandstones, and extensive and pervasive fractures; anticlines tens of miles long by miles wide; thrust faults that juxtapose potential source and reservoir rocks; and oil seeps. Along a fairway from Las Vegas to Elko, for example, thick Mississippian shales contain 4-6% total organic carbon and are oil-prone and thermally mature. This presentation from a laptop computer and LCD projector is a multimedia version of our October 12-14, 1995 field trip to document the hydrocarbon potential of the thrust belt in Clark, Lincoln, and Nye Counties. Outcrop images were recorded by a digital camera that has a resolution equivalent to a 14 inch computer screen; these images were then downloaded to the computer. All of the images were processed digitally on location to enhance picture quality and color contrast. Many were annotated on location with our observations, measurements, and interpretations. These field annotations are supplemented in this presentation by laboratory analyses. The presentation includes full-color, annotated outcrop images, sounds, and animations. The results show the viability of the new, inexpensive digital cameras to geologic field work in which a multimedia report, ready for presentation to management, can be generated in the field.

Chamberlain, A.K. [Cedar Strat Corp., Hiko, NV (United States); Hook, S.C. [Texaco E& P Technology Department, Houston, TX (United States); Frost, K.R. [Texaco Exploration and Production, Inc., Houston, TX (United States)

1996-12-31

400

Digital field trip to the Central Nevada Thrust Belt  

SciTech Connect

Hydrocarbon exploration in the Central Nevada Thrust Belt is still in its infancy. However, this thrust belt contains all the elements necessary for hydrocarbon accumulations: thick, organically-rich shales; reefs, regional unconformities, karst surfaces, porous sandstones, and extensive and pervasive fractures; anticlines tens of miles long by miles wide; thrust faults that juxtapose potential source and reservoir rocks; and oil seeps. Along a fairway from Las Vegas to Elko, for example, thick Mississippian shales contain 4-6% total organic carbon and are oil-prone and thermally mature. This presentation from a laptop computer and LCD projector is a multimedia version of our October 12-14, 1995 field trip to document the hydrocarbon potential of the thrust belt in Clark, Lincoln, and Nye Counties. Outcrop images were recorded by a digital camera that has a resolution equivalent to a 14 inch computer screen; these images were then downloaded to the computer. All of the images were processed digitally on location to enhance picture quality and color contrast. Many were annotated on location with our observations, measurements, and interpretations. These field annotations are supplemented in this presentation by laboratory analyses. The presentation includes full-color, annotated outcrop images, sounds, and animations. The results show the viability of the new, inexpensive digital cameras to geologic field work in which a multimedia report, ready for presentation to management, can be generated in the field.

Chamberlain, A.K. (Cedar Strat Corp., Hiko, NV (United States)); Hook, S.C. (Texaco E P Technology Department, Houston, TX (United States)); Frost, K.R. (Texaco Exploration and Production, Inc., Houston, TX (United States))

1996-01-01

401

Separability of drag and thrust in undulatory animals and machines  

NASA Astrophysics Data System (ADS)

For nearly a century, researchers have tried to understand the swimming of aquatic animals in terms of a balance between the forward thrust from swimming movements and drag on the body. Prior approaches have failed to provide a separation of these two forces for undulatory swimmers such as lamprey and eels, where most parts of the body are simultaneously generating drag and thrust. We nonetheless show that this separation is possible, and delineate its fundamental basis in undulatory swimmers. Our approach unifies a vast diversity of undulatory aquatic animals (anguilliform, sub-carangiform, gymnotiform, bal-istiform, rajiform) and provides design principles for highly agile bioinspired underwater vehicles. This approach has practical utility within biology as well as engineering. It is a predictive tool for use in understanding the role of the mechanics of movement in the evolutionary emergence of morphological features relating to locomotion. For example, we demonstrate that the drag-thrust separation framework helps to predict the observed height of the ribbon fin of electric knifefish, a diverse group of neotropical fish which are an important model system in sensory neurobiology. We also show how drag-thrust separation leads to models that can predict the swimming velocity of an organism or a robotic vehicle.

Bale, Rahul; Shirgaonkar, Anup A.; Neveln, Izaak D.; Bhalla, Amneet Pal Singh; Maciver, Malcolm A.; Patankar, Neelesh A.

2014-12-01

402

The Effect of Atmospheric Pressure on Rocket Thrust -- Part I.  

ERIC Educational Resources Information Center

The first of a two-part question asks: Does the total thrust of a rocket depend on the surrounding pressure? The answer to this question is provided, with accompanying diagrams of rockets. The second part of the question (and answer) are provided in v20 n7, p479, Oct 1982 of this journal. (Author/JN)

Leitner, Alfred

1982-01-01

403

Thrust Improvement of the Magnetically Enhanced Vacuum Arc Thruster (MVAT)  

Microsoft Academic Search

The Magnetically enhanced Vacuum Arc Thruster (MVAT) is a solid propellant micro-thruster based on a pulsed vacuum arc thruster (VAT) that produces precisely controlled impulse bits. The addition of a co-axial magnetic field to the VAT enhances the thrust efficiency of the thruster and collimates the plasma plume, which reduces contamination of the spacecraft. Alameda Applied Sciences Corporation, along with

Benjamin Tang; Luke Idzkowski; Michael Au; Don Parks; Mahadevan Krishnan; John Ziemer

404

Thrust estimation of quadrotor UAV using adaptive observer  

Microsoft Academic Search

In this work, we apply an adaptive observer for estimating the thrust generated by the individual rotors of a quadrotor UAV with uncertain actuator parameters, using a linear dynamic model of the system. In most of the previous works, the implementation of quadrotor control is based on the assumption of a known static relationship between the voltage signal to the

Asad Ullah Awan; Hyoun Jin Kim

2011-01-01

405

Development of thrust stand for low impulse measurement from microthrusters  

NASA Astrophysics Data System (ADS)

A thrust stand has been developed to accurately measure thrust produced by two types of microthrusters—a liquid propellant pulsed plasma thruster (LP-PPT) and a diode laser ablation microthruster. The impulse of LP-PPT ranged from 20 to 80 ?Ns. The diode laser microthruster, which is a new type of microthruster, produces much lower impulse range of 1-10 ?Ns for about 1 s. The mechanical noise induced from the background vibrations becomes a crucial problem for precise estimate of thrust particularly in low impulse measurements. A data analysis method to reduce the effect of mechanical noise is proposed by introducing an additional term in a fitting function. It was verified that the analysis method used in our experimental conditions reduced variance caused by noise down to one-third that of a normal fitting method. The accuracy of the thrust stand is 2.1 ?Ns in the case of the LP-PPT and 0.7 ?Ns in the case of the diode laser microthruster.

Koizumi, H.; Komurasaki, K.; Arakawa, Y.

2004-10-01

406

Development of thrust stand for low impulse measurement from microthrusters  

SciTech Connect

A thrust stand has been developed to accurately measure thrust produced by two types of microthrusters--a liquid propellant pulsed plasma thruster (LP-PPT) and a diode laser ablation microthruster. The impulse of LP-PPT ranged from 20 to 80 {mu}Ns. The diode laser microthruster, which is a new type of microthruster, produces much lower impulse range of 1-10 {mu}Ns for about 1 s. The mechanical noise induced from the background vibrations becomes a crucial problem for precise estimate of thrust particularly in low impulse measurements. A data analysis method to reduce the effect of mechanical noise is proposed by introducing an additional term in a fitting function. It was verified that the analysis method used in our experimental conditions reduced variance caused by noise down to one-third that of a normal fitting method. The accuracy of the thrust stand is 2.1 {mu}Ns in the case of the LP-PPT and 0.7 {mu}Ns in the case of the diode laser microthruster.

Koizumi, H.; Komurasaki, K.; Arakawa, Y. [Department of Aeronautics and Astronautics, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Advanced Energy, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Aeronautics and Astronautics, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

2004-10-01

407

10. DETAIL SHOWING THRUST MEASURING SYSTEM. Looking up from the ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

10. DETAIL SHOWING THRUST MEASURING SYSTEM. Looking up from the test stand deck to east. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-A, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

408

Frictional Characteristics of Thrust Bearing in Scroll Compressor  

NASA Astrophysics Data System (ADS)

This paper presents frictional characteristics of thrust bearing in scroll compressor focusing on the behavior of sliding portion which affects the generation of oil film. The coefficient of friction and tilt angle of sliding portion in the thrust bearing are obtained through both elemental friction test and cylinder pressure measurement of actual scroll compressor. Both tests showed that the coefficient of friction in low contact pressure rose with increase of tilt angle of sliding portion. The value of contact pressure which the coefficient of friction turns into increase was in agreement of the value which tilt angle become to increase. Numerical analysis using mixed lubrication theory was also performed. Analytical result indicated the same characteristics as the experiments, and the correlation between the coefficient of friction and the behavior of sliding portion was confirmed. Based on the experimental and the analytical results obtained here, the optimization of thrust bearing for commercial scroll compressor was applied. 2% improvement of total efficiency in rated condition was archived by optimization of thrust bearing.

Sato, Hajime; Itoh, Takahide; Kobayashi, Hiroyuki

409

Blueschist-facies metamorphism related to regional thrust faulting  

USGS Publications Warehouse

Rocks of the blueschist (glaucophane schist) facies occur throughout the world in narrow tectonic belts associated with ultramafic rocks. In the Coast Range province of California, blueschist rocks are devloped in the eugeosynclinal Franciscan Formation of Late Mesozoic age. The blueschist rocks form a narrow belt for more than 800 km along the eastern margin of this province and commonly are separated from rocks of an overlying thrust plate by serpentinite. Increasing metamorphism upward toward the thrust fault is indicated mineralogically by a transition from pumpellyite to lawsonite and texturally by a transition from metagraywacke to schist. The blueschist metamorphism probably occurred during thrusting in a zone of anomalously high water pressure in the lower plate along the sole of the thrust fault. This tectonic mode of origin for blueschist differs from the generally accepted hypothesis involving extreme depth of burial. Other belts of blueschist-facies rocks, including the Sanbagawa belt of Japan, the marginal synclinal belt of New Zealand, and the blueschist-ultramafic belts of Venezuela, Kamchatka, Ural mountains, and New Caledonia have similar geologic relations and might be explained in the same manner. ?? 1969.

Blake, M.C., Jr.; Irwin, W.P.; Coleman, R.G.

1969-01-01

410

A Regeneratively Cooled Thrust Chamber For The Fastrac Engine  

NASA Technical Reports Server (NTRS)

Abstract This paper presents the development of a low-cost, regeneratively-cooled thrust chamber for the Fastrac engine. The chamber was fabricated using hydraformed copper tubing to form the coolant jacket and wrapped with a fiber reinforced polymer composite Material to form a structural jacket. The thrust chamber design and fabrication approach was based upon Space America. Inc.'s 12,000 lb regeneratively-cooled LOX/kerosene rocket engine. Fabrication of regeneratively cooled thrust chambers by tubewall construction dates back to the early US ballistic missile programs. The most significant innovations in this design was the development of a low-cost process for fabrication from copper tubing (nickel alloy was the usual practice) and use of graphite composite overwrap as the pressure containment, which yields an easily fabricated, lightweight pressure jacket around the copper tubes A regeneratively-cooled reusable thrust chamber can benefit the Fastrac engine program by allowing more efficient (cost and scheduler testing). A proof-of-concept test article has been fabricated and will he tested at Marshall Space Flight Center in the late Summer or Fall of 2000.

Brown, Kendall K.; Sparks, Dave; Woodcock, Gordon

2000-01-01

411

Effect of Operating Frequency on PDE Driven Ejector Thrust Performance  

NASA Technical Reports Server (NTRS)

Results of an on-going study of pulse detonation engine driven ejectors are presented and discussed. The experiments were conducted using a pulse detonation engine (PDE) designed to operate at frequencies up to 50 Hz. The PDE used in these experiments utilizes an equi-molar mixture of oxygen and nitrogen as the oxidizer, and ethylene (C2H4) as the fuel, with the propellant mixture having an equivalence ratio of one. A line of sight laser absorption technique was used to determine the time needed for proper filling of the tube. Thrust measurements were made using an integrated spring damper system coupled with a linear variable displacement transducer. The baseline thrust of the PDE was first measured at each desired frequency and agrees with experimental and modeling results found in the literature. Thrust augmentation measurements were then made for constant diameter ejectors. The ejectors had varying lengths, and two different inlet geometries were tested for each ejector configuration. The parameter space for the study included PDE operation frequency, ejector length, overlap distance and the radius of curvature for the ejector inlets. For the studied experimental matrix, the results showed a maximum thrust augmentation of 106% at an operational frequency of 30 Hz.

Santoro, Robert J.; Pal, Sibtosh; Landry, K.; Shehadeh, R.; Vouvet, N.; Lee, S.-Y.

2005-01-01

412

Regenerative cooling for liquid propellant rocket thrust chambers  

Microsoft Academic Search

This work describes a calculation model for regeneratively cooled rocket thrust chambers. A computational program, based on a one-dimensional coolant pressure drop in the cooling channels. Radiation is included in the model. The channels have rectangular cross sections, the dimensions being determined during the calculations in order to maintain the wall temperature distributions at tolerable levels, with a minimum channel

Rafael Levy Rubin

1994-01-01

413

Cooling of rocket thrust chambers with liquid oxygen  

NASA Technical Reports Server (NTRS)

Rocket engines using high pressure liquid oxygen (LOX) and kerosene (RP-1) as the propellants have been considered for future launch vehicle propulsion. Generally, in regeneratively cooled engines, the fuel is used to cool the combustion chamber. However, hydrocarbons such as RP-1 are limited in their cooling capability at high temperatures and pressures. Therefore, LOX is being considered as an alternative coolant. However, there has been concern as to the effect on the integrity of the chamber liner if oxygen leaks into the combustion zone through fatigue cracks that may develop between the cooling passages and the hot-gas side wall. To address this concern, an investigation was previously conducted with simulated fatigue cracks upstream of the thrust chamber throat. When these chambers were tested, an unexpected melting in the throat region developed which was not in line with the simulated fatigue cracks. The current experimental program was conducted in order to determine the cause for the failure in the earlier thrust chambers and to further investigate the effects of cracks in the thrust chamber liner upstream of the throat. The thrust chambers were tested at oxygen-to-fuel mixture ratios from 1.5 to 2.86 at a nominal chamber pressure of 8.6 MPa. As a result of the test series, the reason for the failure occurring in the earlier work was determined to be injector anomalies. The LOX leaking through the simulated fatigue cracks did not affect the integrity of the chambers.

Armstrong, Elizabeth S.; Schlumberger, Julie A.

1990-01-01

414

The wake structure and thrust performance of a rigid low-aspect-ratio pitching panel.  

PubMed

Thrust performance and wake structure were investigated for a rigid rectangular panel pitching about its leading edge in a free stream. For Re(C) = O(10(4)), thrust coefficient was found to depend primarily on Strouhal number St and the aspect ratio of the panel AR. Propulsive efficiency was sensitive to aspect ratio only for AR less than 0.83; however, the magnitude of the peak efficiency of a given panel with variation in Strouhal number varied inversely with the amplitude to span ratio A/S, while the Strouhal number of optimum efficiency increased with increasing A/S. Peak efficiencies between 9 % and 21 % were measured. Wake structures corresponding to a subset of the thrust measurements were investigated using dye visualization and digital particle image velocimetry. In general, the wakes divided into two oblique jets; however, when operating at or near peak efficiency, the near wake in many cases represented a Kármán vortex street with the signs of the vortices reversed. The three-dimensional structure of the wakes was investigated in detail for AR = 0.54, A/S = 0.31 and Re(C) = 640. Three distinct wake structures were observed with variation in Strouhal number. For approximately 0.20 < St < 0.25, the main constituent of the wake was a horseshoe vortex shed by the tips and trailing edge of the panel. Streamwise variation in the circulation of the streamwise horseshoe legs was consistent with a spanwise shear layer bridging them. For St > 0.25, a reorganization of some of the spanwise vorticity yielded a bifurcating wake formed by trains of vortex rings connected to the tips of the horseshoes. For St > 0.5, an additional structure formed from a perturbation of the streamwise leg which caused a spanwise expansion. The wake model paradigm established here is robust with variation in Reynolds number and is consistent with structures observed for a wide variety of unsteady flows. Movies are available with the online version of the paper. PMID:19746195

Buchholz, James H J; Smits, Alexander J

2008-04-30

415

Jet Radiation Radius  

E-print Network

Jet radiation patterns are indispensable for the purpose of discriminating partons' with different quantum numbers. However, they are also vulnerable to various contaminations from the underlying event, pileup, and radiation of adjacent jets. In order to maximize the discrimination power, it is essential to optimize the jet radius used when analyzing the radiation patterns. We introduce the concept of jet radiation radius which quantifies how the jet radiation is distributed around the jet axes. We study the color and momentum dependence of the jet radiation radius, and discuss two applications: quark-gluon discrimination and $W$ jet tagging. In both cases, smaller (sub)jet radii are preferred for jets with higher PTs, albeit due to different mechanisms: the running of the QCD coupling constant and the boost to a color singlet system. A shrinking cone W jet tagging algorithm is proposed to achieve better discrimination than previous methods.

Zhenyu Han

2014-02-06

416

Inclusive Jets in PHP  

NASA Astrophysics Data System (ADS)

Differential inclusive-jet cross sections have been measured in photoproduction for boson virtualities Q^2 < 1 GeV^2 with the ZEUS detector at HERA using an integrated luminosity of 300 pb^-1. Jets were identified in the laboratory frame using the k_T, anti-k_T or SIScone jet algorithms. Cross sections are presented as functions of the jet pseudorapidity, eta(jet), and the jet transverse energy, E_T(jet). Next-to-leading-order QCD calculations give a good description of the measurements, except for jets with low E_T(jet) and high eta(jet). The cross sections have the potential to improve the determination of the PDFs in future QCD fits. Values of alpha_s(M_Z) have been extracted from the measurements based on different jet algorithms. In addition, the energy-scale dependence of the strong coupling was determined.

Roloff, P.

417

Performance of Simple Gas Foil Thrust Bearings in Air  

NASA Technical Reports Server (NTRS)

Foil bearings are self-acting hydrodynamics devices used to support high speed rotating machinery. The advantages that they offer to process fluid lubricated machines include: high rotational speed capability, no auxiliary lubrication system, non-contacting high speed operation, and improved damping as compared to rigid hydrodynamic bearings. NASA has had a sporadic research program in this technology for almost 6 decades. Advances in the technology and understanding of foil journal bearings have enabled several new commercial products in recent years. These products include oil-free turbochargers for both heavy trucks and automobiles, high speed electric motors, microturbines for distributed power generation, and turbojet engines. However, the foil thrust bearing has not received a complimentary level of research and therefore has become the weak link of oil-free turbomachinery. In an effort to both provide machine designers with basic performance parameters and to elucidate the underlying physics of foil thrust bearings, NASA Glenn Research Center has completed an effort to experimentally measure the performance of simple gas foil thrust bearing in air. The database includes simple bump foil supported thrust bearings with full geometry and manufacturing techniques available to the user. Test conditions consist of air at ambient pressure and temperatures up to 500 C and rotational speeds to 55,000 rpm. A complete set of axial load, frictional torque, and rotational speed is presented for two different compliant sub-structures and inter-pad gaps. Data obtained from commercially available foil thrust bearings both with and without active cooling is presented for comparison. A significant observation made possible by this data set is the speed-load capacity characteristic of foil thrust bearings. Whereas for the foil journal bearing the load capacity increases linearly with rotational speed, the foil thrust bearing operates in the hydrodynamic high speed limit. In this case, the load capacity is constant and in fact often decreases with speed if other factors such as thermal conditions and runner distortions are permitted to dominate the bearing performance.

Bruckner, Robert J.

2012-01-01

418

14 CFR 25.904 - Automatic takeoff thrust control system (ATTCS).  

Code of Federal Regulations, 2012 CFR

...2012-01-01 2012-01-01 false Automatic takeoff thrust control system (ATTCS). 25.904 Section 25.904...AIRPLANES Powerplant General § 25.904 Automatic takeoff thrust control system (ATTCS). Each applicant seeking...

2012-01-01

419

14 CFR 25.904 - Automatic takeoff thrust control system (ATTCS).  

...2014-01-01 2014-01-01 false Automatic takeoff thrust control system (ATTCS). 25.904 Section 25.904...AIRPLANES Powerplant General § 25.904 Automatic takeoff thrust control system (ATTCS). Each applicant seeking...

2014-01-01

420

14 CFR 25.904 - Automatic takeoff thrust control system (ATTCS).  

Code of Federal Regulations, 2011 CFR

...2011-01-01 2011-01-01 false Automatic takeoff thrust control system (ATTCS). 25.904 Section 25.904...AIRPLANES Powerplant General § 25.904 Automatic takeoff thrust control system (ATTCS). Each applicant seeking...

2011-01-01

421

14 CFR 25.904 - Automatic takeoff thrust control system (ATTCS).  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Automatic takeoff thrust control system (ATTCS). 25.904 Section 25.904...AIRPLANES Powerplant General § 25.904 Automatic takeoff thrust control system (ATTCS). Each applicant seeking...

2013-01-01

422

Thermal and Structural Constraints on the Tectonic Evolution of the Idaho-Wyoming-Utah Thrust Belt  

E-print Network

The timing of motion on thrust faults in the Idaho-Wyoming-Utah (IWU) thrust belt comes from synorogenic sediments, apatite thermochronology and direct dating of fault rocks coupled with good geometrical constraints of the subsurface structure...

Chapman, Shay Michael

2013-08-09

423

Free-flight Performance of a Rocket-boosted, Air-launched 16-inch-diameter Ram-jet Engine at Mach Numbers up to 2.20  

NASA Technical Reports Server (NTRS)

The investigation of air-launched ram-jet engines has been extended to include a study of models with a nominal design free-stream Mach number of 2.40. These models require auxiliary thrust in order to attain a flight speed at which the ram jet becomes self-accelerating. A rocket-boosting technique for providing this auxiliary thrust is described and time histories of two rocket-boosted ram-jet flights are presented. In one flight, the model attained a maximum Mach number of 2.20 before a fuel system failure resulted in the destruction of the engine. Performance data for this model are presented in terms of thrust and drag coefficients, diffuser pressure recovery, mass-flow ratio, combustion efficiency, specific fuel consumption, and over-all engine efficiency.

Disher, John H; Kohl, Robert C; Jones, Merle L

1953-01-01

424

Advanced Methods for Aircraft Engine Thrust and Noise Benefits: Nozzle-Inlet Flow Analysis  

NASA Technical Reports Server (NTRS)

Three connected sub-projects were conducted under reported project. Partially, these sub-projects are directed to solving the problems conducted by the HU/FM&AL under two other NASA grants. The fundamental idea uniting these projects is to use untraditional 3D corrugated nozzle designs and additional methods for exhaust jet noise reduction without essential thrust lost and even with thrust augmentation. Such additional approaches are: (1) to add some solid, fluid, or gas mass at discrete locations to the main supersonic gas stream to minimize the negative influence of strong shock waves forming in propulsion systems; this mass addition may be accompanied by heat addition to the main stream as a result of the fuel combustion or by cooling of this stream as a result of the liquid mass evaporation and boiling; (2) to use porous or permeable nozzles and additional shells at the nozzle exit for preliminary cooling of exhaust hot jet and pressure compensation for non-design conditions (so-called continuous ejector with small mass flow rate; and (3) to propose and analyze new effective methods fuel injection into flow stream in air-breathing engines. Note that all these problems were formulated based on detailed descriptions of the main experimental facts observed at NASA Glenn Research Center. Basically, the HU/FM&AL Team has been involved in joint research with the purpose of finding theoretical explanations for experimental facts and the creation of the accurate numerical simulation technique and prediction theory for solutions for current problems in propulsion systems solved by NASA and Navy agencies. The research is focused on a wide regime of problems in the propulsion field as well as in experimental testing and theoretical and numerical simulation analysis for advanced aircraft and rocket engines. The F&AL Team uses analytical methods, numerical simulations, and possible experimental tests at the Hampton University campus. We will present some management activity and theoretical numerical simulation results obtained by the FM&AL Team in the reporting period in accordance with the schedule of the work.

Morgan, Morris H.; Gilinsky, Mikhail M.

2001-01-01

425

Extended performance solar electric propulsion thrust system study. Volume 3: Tradeoff studies of alternate thrust system configurations  

NASA Technical Reports Server (NTRS)

Several thrust system design concepts were evaluated and compared using the specifications of the most advanced 30 cm engineering model thruster as the technology base. Emphasis was placed on relatively high power missions. The extensions in thruster performance required for the Halley's comet mission were defined and alternative thrust system concepts were designed in sufficient detail for comparing mass, efficiency, reliability, structure, and thermal characteristics. Confirmation testing and analysis of thruster and power-processing components were performed. A baseline design was selected from the alternatives considered, and the design analysis and documentation were refined. A program development plan was formulated that outlines the work structure considered necessary for developing, qualifying, and fabricating the flight hardware for the baseline thrust system within the time frame of a project to rendezvous with Halley's comet. An assessment was made of the costs and risks associated with a baseline thrust system as provided to the mission project under this plan. Critical procurements and interfaces were identified and defined.

Hawthorne, E. I.

1977-01-01

426

Modeling of Jet-by-Jet Diffraction Dimitri Papamoschou  

E-print Network

Modeling of Jet-by-Jet Diffraction Dimitri Papamoschou The paper presents an analytical model for the prediction of jet-by-jet diffraction. The source jet is modeled as a radiating cylinder on which one can sources that are becoming prominent in the simulation of jet noise. The scattering jet is modeled as an in

Papamoschou, Dimitri

427

Structural geology of the northern termination of the Crawford Thrust, western Wyoming  

E-print Network

of Michigan; B. S. E. , The University of Michigan Chairman of Advisory Committee: Dr. John H. Spanca The area encompassing the northern term&nation of the C, awford Thrust is studied to determine the deformation related to the termination of a major.... Geologic mapping of the area shows that as displacement on the Crawford Thrust decreases to the north, the Sublette Anticline increases in amplitude and is overturned, and the Sublette Anticline Thrust develops as a forelimb thrust on the Sublette...

Evans, James Paul

2012-06-07

428

Noise tests of a high-aspect-ratio slot nozzle with various V-gutter target thrust reversers  

NASA Technical Reports Server (NTRS)

The results of experiments on the noise generated by a 1.33- by 91.4 cm slot nozzle with various V-gutter reversers, and some thrust measurements are presented. The experiments were conducted with near-ambient temperature jets at nozzle pressure ratios of 1.25 to 3.0, yielding jet velocities of about 190 to 400 m/sec. At pressure ratios of 2 or less, the reversers, in addition to being noisier than the nozzle alone, also had a more uniform directional distribution and more high-frequency noise. At pressure ratios above 2, the nozzle alone generated enough shock noise that the levels were about the same as for the reversers. The maximum overall sound pressure level and the effective overall sound power level both varied with the sixth power of jet velocity over the range tested. The data were scaled up to a size suitable for reversing the wing-flap slot nozzle flow of a 45 400-kg augmentor-wing-type airplane on the ground, yielding perceived noise levels well above 95 PNdB on a 152-m sideline.

Stone, J. R.; Gutierrez, O. A.

1973-01-01

429

Jet Reconstruction at RHIC  

E-print Network

Full jet reconstruction in heavy-ion collisions is expected to provide more sensitive measurements of jet quenching in hot QCD matter at RHIC. In this paper we review recent studies of jets utilizing modern jet reconstruction algorithms and their corresponding background subtraction techniques.

Sevil Salur; for the STAR Collaboration

2010-05-14

430

Jet Physics at CDF  

E-print Network

Recent results on jet physics at the Fermilab Tevatron $p\\bar p$ collider from the CDF Collaboration are presented. The main focus is put on results for the inclusive jet and dijet, $b\\bar b$ dijet, $W/Z+$jets and $W/Z+b$-jets production.

Kenichi Hatakeyama; for the CDF Collaboration

2007-12-12

431

Electrically Driven Jets  

Microsoft Academic Search

Fine jets of slightly conducting viscous fluids and thicker jets or drops of less viscous ones can be drawn from conducting tubes by electric forces. As the potential of the tube relative to a neighbouring plate rises, viscous fluid