Unshrouded Centrifugal Turbopump Impeller Design Methodology

NASA Technical Reports Server (NTRS)

Prueger, George H.; Williams, Morgan; Chen, Wei-Chung; Paris, John; Williams, Robert; Stewart, Eric

2001-01-01

Turbopump weight continues to be a dominant parameter in the trade space for reduction of engine weight. Space Shuttle Main Engine weight distribution indicates that the turbomachinery make up approximately 30% of the total engine weight. Weight reduction can be achieved through the reduction of envelope of the turbopump. Reduction in envelope relates to an increase in turbopump speed and an increase in impeller head coefficient. Speed can be increased until suction performance limits are achieved on the pump or due to alternate constraints the turbine or bearings limit speed. Once the speed of the turbopump is set the impeller tip speed sets the minimum head coefficient of the machine. To reduce impeller diameter the head coefficient must be increased. A significant limitation with increasing head coefficient is that the slope of the head-flow characteristic is affected and this can limit engine throttling range. Unshrouded impellers offer a design option for increased turbopump speed without increasing the impeller head coefficient. However, there are several issues with regard to using an unshrouded impeller: there is a pump performance penalty due to the front open face recirculation flow, there is a potential pump axial thrust problem from the unbalanced front open face and the back shroud face, and since test data is very limited for this configuration, there is uncertainty in the magnitude and phase of the rotordynamic forces due to the front impeller passage. The purpose of the paper is to discuss the design of an unshrouded impeller and to examine the hydrodynamic performance, axial thrust, and rotordynamic performance. The design methodology will also be discussed. This work will help provide some guidelines for unshrouded impeller design.

High-Speed Tests of a Model Twin-Engine Low-Wing Transport Airplane

NASA Technical Reports Server (NTRS)

Becker, John V; LEONARD LLOYD H

1942-01-01

Report presents the results of force tests made of a 1/8-scale model of a twin-engine low-wing transport airplane in the NACA 8-foot high-speed tunnel to investigate compressibility and interference effects of speeds up to 450 miles per hour. In addition to tests of the standard arrangement of the model, tests were made with several modifications designed to reduce the drag and to increase the critical speed.

The Effect of Connecting-passage Diameter on the Performance of a Compression-ignition Engine with a Precombustion Chamber

NASA Technical Reports Server (NTRS)

Moore, C S; Collins, J H

1932-01-01

Results of motoring tests are presented showing the effect of passage diameter on chamber and cylinder compression pressures, maximum pressure differences, and f.m.e.p. over a speed range from 300 to 1,750 r.p.m. Results of engine performance tests are presented which show the effect of passage diameter on m.e.p., explosion pressures, specific fuel consumption, and rates of pressure rise for a range of engine speeds from 500 to 1,500 r.p.m. The cylinder compression pressure, the maximum pressure difference, and the f.m.e.p. decreased rapidly as the passage diameter increased to 29/64 inch, whereas further increase in passage diameter effected only a slight change. The most suitable passage diameter for good engine performance and operating characteristics was 29/64 inch. Passage diameter became less critical with a decrease in engine speed. Therefore, the design should be based on maximum operating speed. Optimum performance and satisfactory combustion control could not be obtained by means of any single diameter of the connecting passage.

Compressibility Effects in Aeronautical Engineering

NASA Technical Reports Server (NTRS)

Stack, John

1941-01-01

Compressible-flow research, while a relatively new field in aeronautics, is very old, dating back almost to the development of the first firearm. Over the last hundred years, researches have been conducted in the ballistics field, but these results have been of practically no use in aeronautical engineering because the phenomena that have been studied have been the more or less steady supersonic condition of flow. Some work that has been done in connection with steam turbines, particularly nozzle studies, has been of value, In general, however, understanding of compressible-flow phenomena has been very incomplete and permitted no real basis for the solution of aeronautical engineering problems in which.the flow is likely to be unsteady because regions of both subsonic and supersonic speeds may occur. In the early phases of the development of the airplane, speeds were so low that the effects of compressibility could be justifiably ignored. During the last war and immediately after, however, propellers exhibited losses in efficiency as the tip speeds approached the speed of sound, and the first experiments of an aeronautical nature were therefore conducted with propellers. Results of these experiments indicated serious losses of efficiency, but aeronautical engineers were not seriously concerned at the time became it was generally possible. to design propellers with quite low tip. speeds. With the development of new engines having increased power and rotational speeds, however, the problems became of increasing importance.

Exhaust emission calibration of two J-58 afterburning turbojet engines at simulated high-altitude, supersonic flight conditions

NASA Technical Reports Server (NTRS)

Holdeman, J. D.

1976-01-01

Emissions of total oxides of nitrogen, nitric oxide, unburned hydrocarbons, carbon monoxide, and carbon dioxide from two J-58 afterburning turbojet engines at simulated high-altitude flight conditions are reported. Test conditions included flight speeds from Mach 2 to 3 at altitudes from 16.0 to 23.5 km. For each flight condition exhaust measurements were made for four or five power levels, from maximum power without afterburning through maximum afterburning. The data show that exhaust emissions vary with flight speed, altitude, power level, and radial position across the exhaust. Oxides of nitrogen emissions decreased with increasing altitude and increased with increasing flight speed. Oxides of nitrogen emission indices with afterburning were less than half the value without afterburning. Carbon monoxide and hydrocarbon emissions increased with increasing altitude and decreased with increasing flight speed. Emissions of these species were substantially higher with afterburning than without.

Design of Intelligent Hydraulic Excavator Control System Based on PID Method

NASA Astrophysics Data System (ADS)

Zhang, Jun; Jiao, Shengjie; Liao, Xiaoming; Yin, Penglong; Wang, Yulin; Si, Kuimao; Zhang, Yi; Gu, Hairong

Most of the domestic designed hydraulic excavators adopt the constant power design method and set 85%~90% of engine power as the hydraulic system adoption power, it causes high energy loss due to mismatching of power between the engine and the pump. While the variation of the rotational speed of engine could sense the power shift of the load, it provides a new method to adjust the power matching between engine and pump through engine speed. Based on negative flux hydraulic system, an intelligent hydraulic excavator control system was designed based on rotational speed sensing method to improve energy efficiency. The control system was consisted of engine control module, pump power adjusted module, engine idle module and system fault diagnosis module. Special PLC with CAN bus was used to acquired the sensors and adjusts the pump absorption power according to load variation. Four energy saving control strategies with constant power method were employed to improve the fuel utilization. Three power modes (H, S and L mode) were designed to meet different working status; Auto idle function was employed to save energy through two work status detected pressure switches, 1300rpm was setting as the idle speed according to the engine consumption fuel curve. Transient overload function was designed for deep digging within short time without spending extra fuel. An increasing PID method was employed to realize power matching between engine and pump, the rotational speed's variation was taken as the PID algorithm's input; the current of proportional valve of variable displacement pump was the PID's output. The result indicated that the auto idle could decrease fuel consumption by 33.33% compared to work in maximum speed of H mode, the PID control method could take full use of maximum engine power at each power mode and keep the engine speed at stable range. Application of rotational speed sensing method provides a reliable method to improve the excavator's energy efficiency and realize power match between pump and engine.

Preliminary Results of an Altitude-Wind-Tunnel Investigation of an Axial-Flow Gas Turbine-Propeller Engine. 5; Combustion-Chamber Characterisitcs

NASA Technical Reports Server (NTRS)

Geisenheyner, Robert M.; Berdysz, Joseph J.

1948-01-01

An investigation to determine the performance and operational characteristics of an axial-flow gas turbine-propeller engine was conducted in the Cleveland altitude wind tunnel. As part of this investigation, the combustion-chamber performance was determined at pressure altitudes from 5000 to 35,000 feet, compressor-inlet ram-pressure ratios of 1.00 and 1.09, and engine speeds from 8000 to 13,000 rpm. Combustion-chamber performance is presented as a function of corrected engine speed and corrected horsepower. For the range of corrected engine speeds investigated, overall total-pressure-loss ratio, cycle efficiency, and the fractional loss in cycle efficiency resulting from pressure losses in the combustion chambers were unaffected by a change in altitude or compressor-inlet ram-pressure ratio. For the range of corrected horsepowers investigated, the total-pressure-loss ratio and the fractional loss in cycle efficiency resulting from pressure losses in the combustion chambers decreased with an increase in corrected horsepower at a constant corrected engine speed. The combustion efficiency remained constant for the range of corrected horsepowers investigated at all corrected engine speeds.

Control logic for exhaust gas driven turbocharger

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

Adeff, G.A.

1991-12-31

This patent describes a method of controlling an exhaust gas driven turbocharger supplying charge air for an internal combustion engine powering vehicle, the turbocharger being adjustable from a normal mode to a power mode in which the charge air available to the engine during vehicle acceleration is increased over that available when the turbocharger is in the normal mode, the vehicle including engine power control means switchable by the vehicle operator from a normal mode to a power mode so that the vehicle operator may selectively elect either the normal mode or the power mode, comprising the steps of measuringmore » the speed of the vehicle, permitting the vehicle operator to elect either the power mode or the normal mode for a subsequent vehicle acceleration, and then adjusting the turbocharger to the power mode when the speed of the vehicle is less than a predetermined reference speed and the vehicle operator has elected to power mode to increase the charge air available to the engine and thereby increasing engine power on a subsequent acceleration of the vehicle.« less

Urban traffic pollution reduction for sedan cars using petrol engines by hydro-oxide gas inclusion.

PubMed

Al-Rousan, Ammar A; Alkheder, Sharaf; Musmar, Sa'ed A

2015-12-01

Petrol cars, in particular nonhybrid cars, contribute significantly to the pollution problem as compared with other types of cars. The originality of this article falls in the direction of using hydro-oxy gas to reduce pollution from petrol car engines. Experiments were performed in city areas at low real speeds, with constant engine speeds in the average of 2500 rpm and at variable velocity ratios (first speed was 10-20 km/hr, second speed was 20-35 km/hr, and third speed was 35-50 km/hr). Results indicated that through using hydro-oxy gas, a noticeable reduction in pollution was recorded. Oxygen (O2) percentage has increased by about 2.5%, and nitric oxide (NO) level has been reduced by about 500 ppm. Carbon monoxide (CO) has decreased by about 2.2%, and also CO2 has decreased by 2.1%. It's worth mentioning that for hybrid system in cars at speeds between 10 and 50 km/hr, the emission percentage change is zero. However, hybrid cars are less abundant than petrol cars. The originality of this paper falls in the direction of using hydro-oxy gas to reduce pollution from petrol car engines. Experiments were performed in city areas at low real speeds, with constant engine speeds in the average of 2500 rpm and at variable velocity ratios (first speed was 10-20 km/hr, second speed was 20-35 km/hr, and third speed was 35-50 km/h).

Dynamics of the inlet system of a four-stroke engine

NASA Technical Reports Server (NTRS)

Boden, R H; Schecter, Harry

1944-01-01

Tests were run on a single-cylinder and a multicylinder four-stroke engine in order to determine the effect of the dynamics of the inlet system upon indicated mean effective pressure. Tests on the single-cylinder engine were made at various speeds, inlet valve timings, and inlet pipe lengths. These tests indicated that the indicated mean effective pressure could be raised considerably at any one speed by the use of a suitably long inlet pipe. Tests at other speeds with this length of pipe showed higher indicated mean effective pressure than with a very short pipe, although not so high as could be obtained with the pipe length adjusted for each speed. A general relation was discovered between optimum time of inlet valve closing and pipe length; namely, that longer pipes require later inlet valve closing in order to be fully effective. Tests were also made on three cylinders connected to a single pipe. With this arrangement, increased volumetric efficiency at low speed was obtainable by using a long pipe, but only with a sacrifice of volumetric efficiency at high speed. Volumetric efficiency at high speed was progressively lower as the pipe length was increased.

Speed limiter integrated fatigue analyzer (SLIFA) for speed and fatigue control on diesel engine truck and bus

NASA Astrophysics Data System (ADS)

Wahyudi, Haris; Pranoto, Hadi; Leman, A. M.; Sebayang, Darwin; Baba, I.

2017-09-01

Every second, the number of road traffic deaths is increased globally with millions more sustaining severe injuries and living with long-term adverse health consequences. Jakarta alone in year 2015 had recorded 556 people died due to road accidents, approximately reached 6.231 road accident cases. The identified major contributory factors of such unfortunate events are both driver fatigue and over speeding habit especially related to the driving of truck and bus. This paper presents the idea on how to control the electronic system from input fuel system of injection pump and the combustion chamber engine will control the valve solenoid in injection pump which can lock and fuel will stop for moment, and speed limit can be success, by using sensor heart rate we can input reduce speed limit when fatigue detection driver. Integration process this tool can be relevant when Speed Limiter Integrated Fatigue Analyser (SLIFA) trial in the diesel engine for truck and bus, the result of this research Speed Limiter Integrated Fatigue Analyser (SLIFA) able to control speed of diesel engine for truck and bus almost 30km/h, 60km/h, and until 70 km/h. The installation of the sensor heart rate as the input speed limit SLIFA would work when the driver is detected to be in the fatigue condition. We make Speed Limiter Integrated Fatigue Analyser (SLIFA) for control and monitoring system for diesel engine in truck and bus. Speed Limiter Integrated Fatigue Analyser (SLIFA) system can save the historical of the speed record, fatigue, rpm, and body temperature of the driver.

Allison V–1710 Engine on a Dynamotor Stand in the Engine Research Building

NASA Image and Video Library

1943-03-21

The first research assignment specifically created for the National Advisory Committee for Aeronautics’ (NACA) new Aircraft Engine Research Laboratory was the integration of a supercharger into the Allison V–1710 engine. The military was relying on the liquid-cooled V–1710 to power several types of World War II fighter aircraft and wanted to improve the engine's speed and altitude performance. Superchargers forced additional airflow into the combustion chamber, which increased the engine’s performance resulting in greater altitudes and speeds. They also generated excess heat that affected the engine cylinders, oil, and fuel. In 1943 the military tasked the new Aircraft Engine Research Laboratory to integrate the supercharger, improve the cooling system, and remedy associated engine knock. Three Allison engines were provided to the laboratory’s research divisions. One group was tasked with improving the supercharger performance, another analyzed the effect of the increased heat on knock in the fuel, one was responsible for improving the cooling system, and another would install the new components on the engine with minimal drag penalties. The modified engines were installed on this 2000-horsepower dynamotor stand in a test cell within the Engine Research Building. The researchers could run the engine at different temperatures, fuel-air ratios, and speeds. When the modifications were complete, the improved V–1710 was flight tested on a P–63A Kingcobra loaned to the NACA for this project.

Demonstration, Testing and Qualification of a High Temperature, High Speed Magnetic Thrust Bearing

NASA Technical Reports Server (NTRS)

DeWitt, Kenneth

2005-01-01

The gas turbine industry has a continued interest in improving engine performance and reducing net operating and maintenance costs. These goals are being realized because of advancements in aeroelasticity, materials, and computational tools such as CFD and engine simulations. These advancements aid in increasing engine thrust-to-weight ratios, specific fuel consumption, pressure ratios, and overall reliability through higher speed, higher temperature, and more efficient engine operation. Currently, rolling element bearing and squeeze film dampers are used to support rotors in gas turbine engines. Present ball bearing configurations are limited in speed (<2 million DN) and temperature (<5OO F) and require both cooling air and an elaborate lubrication system. Also, ball bearings require extensive preventative maintenance in order to assure their safe operation. Since these bearings are at their operational limits, new technologies must be found in order to take advantage of other advances. Magnetic bearings are well suited to operate at extreme temperatures and higher rotational speeds and are a promising solution to the problems that conventional rolling element bearings present. Magnetic bearing technology is being developed worldwide and is considered an enabling technology for new engine designs. Using magnetic bearings, turbine and compressor spools can be radically redesigned to be significantly larger and stiffer with better damping and higher rotational speeds. These advances, a direct result of magnetic bearing technology, will allow significant increases in engine power and efficiency. Also, magnetic bearings allow for real-time, in-situ health monitoring of the system, lower maintenance costs and down time.

Optimization design and performance analysis of a miniature stirling engine

NASA Astrophysics Data System (ADS)

You, Zhanping; Yang, Bo; Pan, Lisheng; Hao, Changsheng

2017-10-01

Under given operation conditions, a stirling engine of 2 kW is designed which takes hydrogen as working medium. Through establishment of adiabatic model, the ways are achieved about performance improving. The ways are raising the temperature of hot terminal, lowering the temperature of cold end, increasing the average cycle pressure, speeding up the speed, phase angle being 90°, stroke volume ratio approximating to 1 and increasing the performance of regenerator.

Effect of cooled EGR on performance and exhaust gas emissions in EFI spark ignition engine fueled by gasoline and wet methanol blends

NASA Astrophysics Data System (ADS)

Rohadi, Heru; Syaiful, Bae, Myung-Whan

2016-06-01

Fuel needs, especially the transport sector is still dominated by fossil fuels which are non-renewable. However, oil reserves are very limited. Furthermore, the hazardous components produced by internal combustion engine forces many researchers to consider with alternative fuel which is environmental friendly and renewable sources. Therefore, this study intends to investigate the impact of cooled EGR on the performance and exhaust gas emissions in the gasoline engine fueled by gasoline and wet methanol blends. The percentage of wet methanol blended with gasoline is in the range of 5 to 15% in a volume base. The experiment was performed at the variation of engine speeds from 2500 to 4000 rpm with 500 intervals. The re-circulated exhaust gasses into combustion chamber was 5%. The experiment was performed at the constant engine speed. The results show that the use of cooled EGR with wet methanol of 10% increases the brake torque up to 21.3%. The brake thermal efficiency increases approximately 39.6% using cooled EGR in the case of the engine fueled by 15% wet methanol. Brake specific fuel consumption for the engine using EGR fueled by 10% wet methanol decreases up to 23% at the engine speed of 2500 rpm. The reduction of CO, O2 and HC emissions was found, while CO2 increases.

Preliminary Results of an Altitude-Wind-Tunnel Investigation of a TG-100A Gas Turbine-Propeller Engine. V; Combustion-Chamber Characteristics

NASA Technical Reports Server (NTRS)

Gensenheyner, Robert M.; Berdysz, Joseph J.

1947-01-01

An investigation to determine the performance and operational characteristics of the TG-1OOA gas turbine-propeller engine was conducted in the Cleveland altitude wind tunnel. As part of this investigation, the combustion-chamber performance was determined at pressure altitudes from 5000 to 35,000 feet, compressor-inlet rm-pressure ratios of 1.00 and 1.09, and engine speeds from 8000 to 13,000 rpm. Combustion-chamber performance is presented as a function of corrected engine speed and.correcte& horsepower. For the range of corrected engine speeds investigated, over-all total-pressure-loss ratio, cycle efficiency, ana the frac%ional loss in cycle efficiency resulting from pressure losses in the combustion chambers were unaffected by a change in altitude or compressor-inlet ram-pressure ratio. The scatter of combustion- efficiency data tended to obscure any effect of altitude or ram-pressure ratio. For the range of corrected horse-powers investigated, the total-pressure-loss ratio an& the fractional loss in cycle efficiency resulting from pressure losses in the combustion chambers decreased with an increase in corrected horsepower at a constant corrected engine speed. The combustion efficiency remained constant for the range of corrected horse-powers investigated at all corrected engine speeds.

Emissions and Total Energy Consumption of a Multicylinder Piston Engine Running on Gasoline and a Hydrogen-gasoline Mixture

NASA Technical Reports Server (NTRS)

Cassidy, J. F.

1977-01-01

A multicylinder reciprocating engine was used to extend the efficient lean operating range of gasoline by adding hydrogen. Both bottled hydrogen and hydrogen produced by a research methanol steam reformer were used. These results were compared with results for all gasoline. A high-compression-ratio, displacement production engine was used. Apparent flame speed was used to describe the differences in emissions and performance. Therefore, engine emissions and performance, including apparent flame speed and energy lost to the cooling system and the exhaust gas, were measured over a range of equivalence ratios for each fuel. All emission levels decreased at the leaner conditions. Adding hydrogen significantly increased flame speed over all equivalence ratios.

Effect of water injection and off scheduling of variable inlet guide vanes, gas generator speed and power turbine nozzle angle on the performance of an automotive gas turbine engine

NASA Technical Reports Server (NTRS)

Warren, E. L.

1980-01-01

The Chrysler/ERDA baseline automotive gas turbine engine was used to experimentally determine the power augmentation and emissions reductions achieved by the effect of variable compressor and power engine geometry, water injection downstream of the compressor, and increases in gas generator speed. Results were dependent on the mode of variable geometry utilization. Over 20 percent increase in power was accompanied by over 5 percent reduction in SFC. A fuel economy improvement of at least 6 percent was estimated for a vehicle with a 75 kW (100 hp) engine which could be augmented to 89 kW (120 hp) relative to an 89 Kw (120 hp) unaugmented engine.

An airline study of advanced technology requirements for advanced high speed commercial transport engines. 1: Engine design study assessment

NASA Technical Reports Server (NTRS)

Sallee, G. P.

1973-01-01

The advanced technology requirements for an advanced high speed commercial tranport engine are presented. The results of the phase 1 study effort cover the following areas: (1) statement of an airline's major objectives for future transport engines, (2) airline's method of evaluating engine proposals, (3) description of an optimum engine for a long range subsonic commercial transport including installation and critical design features, (4) discussion of engine performance problems and experience with performance degradation, (5) trends in engine and pod prices with increasing technology and objectives for the future, (6) discussion of the research objectives for composites, reversers, advanced components, engine control systems, and devices to reduce the impact of engine stall, and (7) discussion of the airline objectives for noise and pollution reduction.

Method for evaluating the reliability of compressor impeller of turbocharger for vehicle application in plateau area

NASA Astrophysics Data System (ADS)

Wang, Zheng; Wang, Zengquan; Wang, A.-na; Zhuang, Li; Wang, Jinwei

2016-10-01

As turbocharging diesel engines for vehicle application are applied in plateau area, the environmental adaptability of engines has drawn more attention. For the environmental adaptability problem of turbocharging diesel engines for vehicle application, the present studies almost focus on the optimization of performance match between turbocharger and engine, and the reliability problem of turbocharger is almost ignored. The reliability problem of compressor impeller of turbocharger for vehicle application when diesel engines operate in plateau area is studied. Firstly, the rule that the rotational speed of turbocharger changes with the altitude height is presented, and the potential failure modes of compressor impeller are analyzed. Then, the failure behavior models of compressor impeller are built, and the reliability models of compressor impeller operating in plateau area are developed. Finally, the rule that the reliability of compressor impeller changes with the altitude height is studied, the measurements for improving the reliability of the compressor impellers of turbocharger operating in plateau area are given. The results indicate that when the operating speed of diesel engine is certain, the rotational speed of turbocharger increases with the increase of altitude height, and the failure risk of compressor impeller with the failure modes of hub fatigue and blade resonance increases. The reliability of compressor impeller decreases with the increase of altitude height, and it also decreases as the increase of number of the mission profile cycle of engine. The method proposed can not only be used to evaluating the reliability of compressor impeller when diesel engines operate in plateau area but also be applied to direct the structural optimization of compressor impeller.

A Sensitivity Study of Commercial Aircraft Engine Response for Emergency Situations

NASA Technical Reports Server (NTRS)

Csank, Jeffrey T.; May, Ryan D.; Litt, Jonathan S.; Guo, Ten-Huei

2011-01-01

This paper contains the details of a sensitivity study in which the variation in a commercial aircraft engine's outputs is observed for perturbations in its operating condition inputs or control parameters. This study seeks to determine the extent to which various controller limits can be modified to improve engine performance, while capturing the increased risk that results from the changes. In an emergency, the engine may be required to produce additional thrust, respond faster, or both, to improve the survivability of the aircraft. The objective of this paper is to propose changes to the engine controller and determine the costs and benefits of the additional capabilities produced by the engine. This study indicates that the aircraft engine is capable of producing additional thrust, but at the cost of an increased risk of an engine failure due to higher turbine temperatures and rotor speeds. The engine can also respond more quickly to transient commands, but this action reduces the remaining stall margin to possibly dangerous levels. To improve transient response in landing scenarios, a control mode known as High Speed Idle is proposed that increases the responsiveness of the engine and conserves stall margin

High-Lift Systems on Commercial Subsonic Airliners

NASA Technical Reports Server (NTRS)

Rudolph, Peter K. C.

1996-01-01

The early breed of slow commercial airliners did not require high-lift systems because their wing loadings were low and their speed ratios between cruise and low speed (takeoff and landing) were about 2:1. However, even in those days the benefit of high-lift devices was recognized. Simple trailing-edge flaps were in use, not so much to reduce landing speeds, but to provide better glide-slope control without sideslipping the airplane and to improve pilot vision over the nose by reducing attitude during low-speed flight. As commercial-airplane cruise speeds increased with the development of more powerful engines, wing loadings increased and a real need for high-lift devices emerged to keep takeoff and landing speeds within reasonable limits. The high-lift devices of that era were generally trailing-edge flaps. When jet engines matured sufficiently in military service and were introduced commercially, airplane speed capability had to be increased to best take advantage of jet engine characteristics. This speed increase was accomplished by introducing the wing sweep and by further increasing wing loading. Whereas increased wing loading called for higher lift coefficients at low speeds, wing sweep actually decreased wing lift at low speeds. Takeoff and landing speeds increased on early jet airplanes, and, as a consequence, runways worldwide had to be lengthened. There are economical limits to the length of runways; there are safety limits to takeoff and landing speeds; and there are speed limits for tires. So, in order to hold takeoff and landing speeds within reasonable limits, more powerful high-lift devices were required. Wing trailing-edge devices evolved from plain flaps to Fowler flaps with single, double, and even triple slots. Wing leading edges evolved from fixed leading edges to a simple Krueger flap, and from fixed, slotted leading edges to two- and three-position slats and variable-camber (VC) Krueger flaps. The complexity of high-lift systems probably peaked on the Boeing 747, which has a VC Krueger flap and triple-slotted, inboard and outboard trailing-edge flaps. Since then, the tendency in high-lift system development has been to achieve high levels of lift with simpler devices in order to reduce fleet acquisition and maintenance costs. The intent of this paper is to: (1) review available high-lift devices, their functions, and design criteria; (2) appraise high-lift systems presently in service on commercial air liners; (3) present personal study results on high-lift systems; (4) develop a weight and cost model for high-lift systems; and (5) discuss the development tendencies of future high-lift systems.

Possible improvements in gasoline engines

NASA Technical Reports Server (NTRS)

Ziembinski, S

1923-01-01

High-compression engines are investigated with the three main objects being elimination of vibration, increase of maximum efficiency, and conservation of this efficiency at the highest possible speeds.

Supercharged two-cycle engines employing novel single element reciprocating shuttle inlet valve mechanisms and with a variable compression ratio

NASA Technical Reports Server (NTRS)

Wiesen, Bernard (Inventor)

2008-01-01

This invention relates to novel reciprocating shuttle inlet valves, effective with every type of two-cycle engine, from small high-speed single cylinder model engines, to large low-speed multiple cylinder engines, employing spark or compression ignition. Also permitting the elimination of out-of-phase piston arrangements to control scavenging and supercharging of opposed-piston engines. The reciprocating shuttle inlet valve (32) and its operating mechanism (34) is constructed as a single and simple uncomplicated member, in combination with the lost-motion abutments, (46) and (48), formed in a piston skirt, obviating the need for any complex mechanisms or auxiliary drives, unaffected by heat, friction, wear or inertial forces. The reciprocating shuttle inlet valve retains the simplicity and advantages of two-cycle engines, while permitting an increase in volumetric efficiency and performance, thereby increasing the range of usefulness of two-cycle engines into many areas that are now dominated by the four-cycle engine.

Ultrafine particle emission characteristics of diesel engine by on-board and test bench measurement.

PubMed

Huang, Cheng; Lou, Diming; Hu, Zhiyuan; Tan, Piqiang; Yao, Di; Hu, Wei; Li, Peng; Ren, Jin; Chen, Changhong

2012-01-01

This study investigated the emission characteristics of ultrafine particles based on test bench and on-board measurements. The bench test results showed the ultrafine particle number concentration of the diesel engine to be in the range of (0.56-8.35) x 10(8) cm(-3). The on-board measurement results illustrated that the ultrafine particles were strongly correlated with changes in real-world driving cycles. The particle number concentration was down to 2.0 x 10(6) cm(-3) and 2.7 x 10(7) cm(-3) under decelerating and idling operations and as high as 5.0 x 10(8) cm(-3) under accelerating operation. It was also indicated that the particle number measured by the two methods increased with the growth of engine load at each engine speed in both cases. The particle number presented a "U" shaped distribution with changing speed at high engine load conditions, which implies that the particle number will reach its lowest level at medium engine speeds. The particle sizes of both measurements showed single mode distributions. The peak of particle size was located at about 50-80 nm in the accumulation mode particle range. Nucleation mode particles will significantly increase at low engine load operations like idling and decelerating caused by the high concentration of unburned organic compounds.

40 CFR 85.2214 - Two speed idle test-EPA 81.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 18 2011-07-01 2011-07-01 false Two speed idle test-EPA 81. 85.2214... Tests § 85.2214 Two speed idle test—EPA 81. (a)(1) General calendar year applicability. The test... exhaust pipes originate from a common point. (4) The engine speed is increased to 2500 ±300 rpm, with...

40 CFR 85.2214 - Two speed idle test-EPA 81.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 18 2010-07-01 2010-07-01 false Two speed idle test-EPA 81. 85.2214... Tests § 85.2214 Two speed idle test—EPA 81. (a)(1) General calendar year applicability. The test... exhaust pipes originate from a common point. (4) The engine speed is increased to 2500 ±300 rpm, with...

Background and principles of throttles-only flight control

NASA Technical Reports Server (NTRS)

Burcham, Frank W., Jr.

1995-01-01

There have been many cases in which the crew of a multi-engine airplane had to use engine thrust for emergency flight control. Such a procedure is very difficult, because the propulsive control forces are small, the engine response is slow, and airplane dynamics such as the phugoid and dutch roll are difficult to damp with thrust. In general, thrust increases are used to climb, thrust decreases to descend, and differential thrust is used to turn. Average speed is not significantly affected by changes in throttle setting. Pitch control is achieved because of pitching moments due to speed changes, from thrust offset, and from the vertical component of thrust. Roll control is achieved by using differential thrust to develop yaw, which, through the normal dihedral effect, causes a roll. Control power in pitch and roll tends to increase as speed decreases. Although speed is not controlled by the throttles, configuration changes are often available (lowering gear, flaps, moving center-of-gravity) to change the speed. The airplane basic stability is also a significant factor. Fuel slosh and gyroscopic moments are small influences on throttles-only control. The background and principles of throttles-only flight control are described.

Preliminary Results of Altitude-Wind-Tunnel Investigation of X24C-4B Turbojet Engine. I - Pressure and Temperature Distributions

NASA Technical Reports Server (NTRS)

Prince, William R.; Hawkins, W. Kent

1947-01-01

Pressures and temperatures throughout the X24C-4B turbojet engine are presented in both tabular and graphical forms to show the effect of altitude, flight Mach number, and engine speed on the internal operation of the engine. These data were obtained in the NACA Cleveland altitude wind tunnel at simulated altitudes from 5000 to 45,000 feet, simulated flight Mach numbers from 0.25 to 1.08, and engine speeds from 4000 to 12,500 rpm. Location and detail drawings of the instrumentation installed at seven survey stations in the engine are shown. Application of generalization factors to pressures and temperatures at each measuring station for the range of altitudes investigated showed that the data did not generalize above an altitude of 25,000 feet. Total-pressure distribution at the compressor outlet varied only with change in engine speed. At altitudes above 35,000 feet and engine speeds above 11,000 rpm, the peak temperature at the turbine-outlet annulus moved inward toward the root of the blade, which is undesirable from blade-stress considerations. The temperature levels at the turbine outlet and the exhaust-nozzle outlet were lowered as the Mach number was increased. The static-pressure measurements obtained at each stator stage of the compressor showed a pressure drop through the inlet guide vanes and the first-stage rotor at high engine speeds. The average values measured by the manufacturer's instrumentation werein close agreement with the average values obtained with NACA instrumentation.

Ignition study of a petrol/CNG single cylinder engine

NASA Astrophysics Data System (ADS)

Khan, N.; Saleem, Z.; Mirza, A. A.

2005-11-01

Benefits of laser ignition over the electrical ignition system for Compressed Natural Gas (CNG) engines have fuelled automobile industry and led to an extensive research on basic characteristics to switch over to the emerging technologies. This study was undertaken to determine the electrical and physical characteristics of the electric spark ignition of single cylinder petrol/CNG engine to determine minimum ignition requirements and timeline of ignition events to use in subsequent laser ignition study. This communication briefly reviews the ongoing research activities and reports the results of this experimental study. The premixed petrol and CNG mixtures were tested for variation of current and voltage characteristics of the spark with speed of engine. The current magnitude of discharge circuit was found to vary linearly over a wide range of speed but the stroke to stroke fire time was found to vary nonlinearly. The DC voltage profiles were observed to fluctuate randomly during ignition process and staying constant in rest of the combustion cycle. Fire to fire peaks of current amplitudes fluctuated up to 10% of the peak values at constant speed but increased almost linearly with increase in speed. Technical barriers of laser ignition related to threshold minimum ignition energy, inter-pulse durations and firing sequence are discussed. Present findings provide a basic initiative and background information for designing suitable timeline algorithms for laser ignited leaner direct injected CNG engines.

Investigation of the I-40 Jet-Propulsion Engine in the Cleveland Altitude Wind Tunnel. V - Operational Characteristics. 5; Operational Characteristics

NASA Technical Reports Server (NTRS)

Golladay, Richard L.; Gendler, Stanley L.

1947-01-01

An investigation has been conducted in the Cleveland altitude wind tunnel to determine the operational characteristics of the I-40 jet-propulsion engine over a range of pressure altitudes from 10,000 to 50,000 feet and ram-pressure ratios from 1.00 to 1.76. Engine operational data were obtained with the engine in the standard configuration and with various modifications of the fuel system, the electrical system, and the combustion chambers. The effects of altitude and airspeed on operating speed range, starting, windmilli.ng, acceleration, speed regulation, cooling, and vibration of the standard and modified engines were determined, and damage to parts was noted. Maximum engine speed was obtainable at all altitudes and airspeeds wi th each fuel-control system investigated. The minimum idling speed was raised by increases in altitude and airspeed. The lowest minimum stable speeds were obtained with the standard configuration using 40-gallon nozzles with individual metering plugs. The engine was started normally at altitudes as high as 20,000 feet with all of the fuel systems and ignition combinations except one. Ignition at 70,000 feet was difficult and, although successful ignition occurred, acceleration was slow and usually characterized by excessive tail-pipe temperature. During windmilling investigations of the engine equipped with the standard fuel system, the engine could not be started at ram-pressure ratios of 1.1 to 1.7 at altitudes of 10,000, 20,000 and 30,000 feet. When equipped with the production barometric and Monarch 40-gallon nozzles, the engine accelerated in 12 seconds from an engine speed of 6000 rpm to 11,000 rpm at 20,000 feet and an average tail-pipe temperature of 11000 F. At the same altitude and temperature, all the engine configurations had approximately the same rate of acceleration. The Woodward governor produced the safest accelerations, inasmuch as it could be adjusted to automatically prevent acceleration blow out. The engine speed was held constant by the Woodward governor and the Edwards regulator during simulated dives and climbs at constant throttle position. The bearing cooling system was satisfactory at all altitudes and airspeeds. The engines operated without serious failure, although the exhaust cone, the tail pipe, and the airplane fuselage were damaged during altitude starts.

Investigation of Water-spray Cooling of Turbine Blades in a Turbojet Engine

NASA Technical Reports Server (NTRS)

Freche, John C; Stelpflug, William J

1953-01-01

An analytical and experimental investigation was made with a J33-A-9 engine to determine the effectiveness of spray cooling as a means of increasing thrust by permitting engine operation at inlet-gas temperatures and speeds above rated. With the assumption of adequate spray cooling at a coolant-to-gas flow ratio of 3 percent, calculations for the sea-level static condition indicated a thrust may be achieved by engine operation at an inlet-gas temperature of 2000 degrees F and an overspeed of 10 percent. Of the water-injection configurations investigated experimentally, those located in the inner ring of the stator diaphragm provided the best cooling at rated engine speed.

Effect of air-entry angle on performance of a 2-stroke-cycle compression-ignition engine

NASA Technical Reports Server (NTRS)

Earle, Sherod L; Dutee, Francis J

1937-01-01

An investigation was made to determine the effect of variations in the horizontal and vertical air-entry angles on the performance characteristics of a single-cylinder 2-stroke-cycle compression-ignition test engine. Performance data were obtained over a wide range of engine speed, scavenging pressure, fuel quantity, and injection advance angle with the optimum guide vanes. Friction and blower-power curves are included for calculating the indicated and net performances. The optimum horizontal air-entry angle was found to be 60 degrees from the radial and the optimum vertical angle to be zero, under which conditions a maximum power output of 77 gross brake horsepower for a specific fuel consumption of 0.52 pound per brake horsepower-hour was obtained at 1,800 r.p.m. and 16-1/2 inches of Hg scavenging pressure. The corresponding specific output was 0.65 gross brake horsepower per cubic inch of piston displacement. Tests revealed that the optimum scavenging pressure increased linearly with engine speed. The brake mean effective pressure increased uniformly with air quantity per cycle for any given vane angle and was independent of engine speed and scavenging pressure.

Performance of Blowdown Turbine driven by Exhaust Gas of Nine-Cylinder Radial Engine

DTIC Science & Technology

1944-12-01

blade speed to mean jet speed FIQUBE 6.—Variation of mean turbine efficiency with ratio of blade speed to moan Jot speed. Engine speed, 2000 rpm; full...conventional turbo - supercharger axe used in series, the blowdown turbine may be geared to the engine . Aircraft engines are operated at high speed for...guide vanes in blowdown-turblno noule box. PERFORMANCE OF BLOWDOWN TURBINE DRIVEN BT EXHAUST GAS OF RADIAL ENGINE 245 (6) Diaphragm

Effects of Exhaust Gas Recirculation on Performance and Emission Characteristic of SI Engine using Hydrogen and CNG Blends

NASA Astrophysics Data System (ADS)

Nitnaware, Pravin Tukaram; Suryawanshi, Jiwak G.

2018-01-01

This paper shows exhaust gas recirculation (EGR) effects on multi-cylinder bi-fuel SI engine using blends of 0, 5, 10 and 15% hydrogen by energy with CNG. All trials are performed at a speed of 3000, 3500 and 4000 rpm with EGR rate of 0, 5, 10 and 15%, with equal spark timing and injection pressure of 2.6 bar. At specific hydrogen percentage with increase in EGR rate NOx emission reduces drastically and increases with increase in hydrogen addition. Hydrocarbon (HC) and carbon monoxide (CO) emission decreases with increase in speed and hydrogen addition. There is considerable improvement in brake thermal efficiency (BTE) and brake specific energy consumption (BSEC) at 15% EGR rate. At 3000 rpm, 5% EGR rate with 5% hydrogen had shown maximum cylinder pressure. Brake specific fuel consumption (b.s.f.c) increased with increase in EGR rate and decreased with increase in hydrogen addition for all speeds.

Radially leaned outlet guide vanes for fan source noise reduction

NASA Technical Reports Server (NTRS)

Kazin, S. B.

1973-01-01

Two quiet engine program half scale fans one with a subsonic and the other with a supersonic fan tip speed at takeoff were run with 30 degree leaned and radial outlet guide vanes. Acoustic data at takeoff fan speed on the subsonic tip speed fan showed decreases in 200-foot sideline noise of from 1 to 2 PNdb. The supersonic tip speed fan a takeoff fan speed, however, showed noise increases of up 3 PNdb and a decrease in fan efficiency. At approach fan speed, the subsonic tip speed fan showed a noise decrease of 2.3 PNdb at the 200-foot sideline maximum angle and an increase in efficiency. The supersonic tip speed fan showed noise increase of 3.5 PNdb and no change in efficiency. The decrease in fan efficiency and the nature of the noise increase largely high frequency broadband noise lead to the speculation that an aerodynamic problem occurred.

Use of optimization to predict the effect of selected parameters on commuter aircraft performance

NASA Technical Reports Server (NTRS)

Wells, V. L.; Shevell, R. S.

1982-01-01

An optimizing computer program determined the turboprop aircraft with lowest direct operating cost for various sets of cruise speed and field length constraints. External variables included wing area, wing aspect ratio and engine sea level static horsepower; tail sizes, climb speed and cruise altitude were varied within the function evaluation program. Direct operating cost was minimized for a 150 n.mi typical mission. Generally, DOC increased with increasing speed and decreasing field length but not by a large amount. Ride roughness, however, increased considerably as speed became higher and field length became shorter.

Simultaneously firing two cylinders of an even firing camless engine

DOEpatents

Brennan, Daniel G

2014-03-11

A valve control system includes an engine speed control module that determines an engine speed and a desired engine stop position. A piston position module determines a desired stopping position of a first piston based on the desired engine stop position. A valve control module receives the desired stopping position, commands a set of valves to close at the desired stopping position if the engine speed is less than a predetermined shutdown threshold, and commands the set of valves to reduce the engine speed if the engine speed is greater than the predetermined shutdown threshold.

Systematic Engine Uprate Technology Development and Deployment for Pipeline Compressor Engines through Increased Torque

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

Dennis Schmitt; Daniel Olsen

2005-09-30

Three methods were utilized to analyze key components of slow-speed, large-bore, natural gas integral engines. These three methods included the application of computational fluid dynamics (CFD), dynamic modal analysis using finite element analysis (FEA), and a stress analysis method also using FEA. The CFD analysis focuses primarily on the fuel mixing in the combustion chamber of a TLA engine. Results indicate a significant increase in the homogeneity of the air and fuel using high-pressure fuel injection (HPFI) instead of standard low-pressure mechanical gas admission valve (MGAV). A modal analysis of three engine crankshafts (TLA-6, HBA-6, and GMV-10) is developed andmore » presented. Results indicate that each crankshaft has a natural frequency and corresponding speed that is well away from the typical engine operating speed. A frame stress analysis method is also developed and presented. Two different crankcases are examined. A TLA-6 crankcase is modeled and a stress analysis is performed. The method of dynamic load determination, model setup, and the results from the stress analysis are discussed. Preliminary results indicate a 10%-15% maximum increase in frame stress due to a 20% increase in HP. However, the high stress regions were localized. A new hydraulically actuated mechanical fuel valve is also developed and presented. This valve provides equivalent high-energy (supersonic) fuel injection comparable to a HPFI system, at 1/5th of the natural gas fuel pressure. This valve was developed in cooperation with the Dresser-Rand Corporation.« less

Operating Temperatures of a Sodium-Cooled Exhaust Valve as Measured by a Thermocouple

NASA Technical Reports Server (NTRS)

Sanders, J. C.; Wilsted, H. D.; Mulcahy, B. A.

1943-01-01

A thermocouple was installed in the crown of a sodium-cooled exhaust valve. The valve was then tested in an air-cooled engine cylinder and valve temperatures under various engine operating conditions were determined. A temperature of 1337 F was observed at a fuel-air ratio of 0.064, a brake mean effective pressure of 179 pounds per square inch, and an engine speed of 2000 rpm. Fuel-air ratio was found to have a large influence on valve temperature, but cooling-air pressure and variation in spark advance had little effect. An increase in engine power by change of speed or mean effective pressure increased the valve temperature. It was found that the temperature of the rear spark-plug bushing was not a satisfactory indication of the temperature of the exhaust valve.

An Assessment of Gas Foil Bearing Scalability and the Potential Benefits to Civilian Turbofan Engines

NASA Technical Reports Server (NTRS)

Bruckner, Robert J.

2010-01-01

Over the past several years the term oil-free turbomachinery has been used to describe a rotor support system for high speed turbomachinery that does not require oil for lubrication, damping, or cooling. The foundation technology for oil-free turbomachinery is the compliant foil bearing. This technology can replace the conventional rolling element bearings found in current engines. Two major benefits are realized with this technology. The primary benefit is the elimination of the oil lubrication system, accessory gearbox, tower shaft, and one turbine frame. These components account for 8 to 13 percent of the turbofan engine weight. The second benefit that compliant foil bearings offer to turbofan engines is the capability to operate at higher rotational speeds and shaft diameters. While traditional rolling element bearings have diminished life, reliability, and load capacity with increasing speeds, the foil bearing has a load capacity proportional to speed. The traditional applications for foil bearings have been in small, lightweight machines. However, recent advancements in the design and manufacturing of foil bearings have increased their potential size. An analysis, grounded in experimentally proven operation, is performed to assess the scalability of the modern foil bearing. This analysis was coupled to the requirements of civilian turbofan engines. The application of the foil bearing to larger, high bypass ratio engines nominally at the 120 kN (approx.25000 lb) thrust class has been examined. The application of this advanced technology to this system was found to reduce mission fuel burn by 3.05 percent.

The effects of emission control strategies on light-absorbing carbon emissions from a modern heavy-duty diesel engine.

PubMed

Robinson, Michael A; Olson, Michael R; Liu, Z Gerald; Schauer, James J

2015-06-01

Control of atmospheric black carbon (BC) and brown carbon (BrC) has been proposed as an important pathway to climate change mitigation, but sources of BC and BrC are still not well understood. In order to better identify the role of modern heavy-duty diesel engines on the production of BC and BrC, emissions from a heavy-duty diesel engine operating with different emission control strategies were examined using a source dilution sampling system. The effect of a diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) on light-absorbing carbon (LAC) was evaluated at three steady-state engine operation modes: idle, 50% speed and load, and 100% speed and load. LAC was measured with four different engine configurations: engine out, DOC out, DPF out, and engine out with an altered combustion calibration. BC and BrC emission rates were measured with the Aethalometer (AE-31). EC and BC emission rates normalized to the mass of CO₂emitted increased with increasing engine speed and load. Emission rates normalized to brake-specific work did not exhibit similar trends with speed and load, but rather the highest emission rate was measured at idle. EC and OC emissions were reduced by 99% when the DOC and DPF architecture was applied. The application of a DPF was equally effective at removing 99% of the BC fraction of PM, proving to be an important control strategy for both LAC and PM. BC emissions were unexpectedly increased across the DOC, seemingly due to a change aerosol optical properties. Removal of exhaust gas recirculation (EGR) flow due to simulated EGR cooler failure caused a large increase in OC and BrC emission rates at idle, but had limited influence during high load operation. LAC emissions proved to be sensitive to the same control strategies effective at controlling the total mass of diesel PM. In the context of black carbon emissions, very small emission rates of brown carbon were measured over a range of control technologies and engine operating conditions. During specific idle engine operation without EGR and adjusted fueling conditions, brown carbon can be formed in significant amounts, requiring careful management tactics. Control technologies for particulate matter are very effective for light-absorbing carbon, reducing black carbon emissions to near zero for modern engines equipped with a DPF. Efforts to control atmospheric brown carbon need to focus on other sources other than modern diesel engines, such as biomass burning.

Combustion in a High-Speed Compression-Ignition Engine

NASA Technical Reports Server (NTRS)

Rothrock, A M

1933-01-01

An investigation conducted to determine the factors which control the combustion in a high-speed compression-ignition engine is presented. Indicator cards were taken with the Farnboro indicator and analyzed according to the tangent method devised by Schweitzer. The analysis show that in a quiescent combustion chamber increasing the time lag of auto-ignition increases the maximum rate of combustion. Increasing the maximum rate of combustion increases the tendency for detonation to occur. The results show that by increasing the air temperature during injection the start of combustion can be forced to take place during injection and so prevent detonation from occurring. It is shown that the rate of fuel injection does not in itself control the rate of combustion.

Engine lubrication circuit including two pumps

DOEpatents

Lane, William H.

2006-10-03

A lubrication pump coupled to the engine is sized such that the it can supply the engine with a predetermined flow volume as soon as the engine reaches a peak torque engine speed. In engines that operate predominately at speeds above the peak torque engine speed, the lubrication pump is often producing lubrication fluid in excess of the predetermined flow volume that is bypassed back to a lubrication fluid source. This arguably results in wasted power. In order to more efficiently lubricate an engine, a lubrication circuit includes a lubrication pump and a variable delivery pump. The lubrication pump is operably coupled to the engine, and the variable delivery pump is in communication with a pump output controller that is operable to vary a lubrication fluid output from the variable delivery pump as a function of at least one of engine speed and lubrication flow volume or system pressure. Thus, the lubrication pump can be sized to produce the predetermined flow volume at a speed range at which the engine predominately operates while the variable delivery pump can supplement lubrication fluid delivery from the lubrication pump at engine speeds below the predominant engine speed range.

Predicted Performance of a Thrust-Enhanced SR-71 Aircraft with an External Payload

NASA Technical Reports Server (NTRS)

Conners, Timothy R.

1997-01-01

NASA Dryden Flight Research Center has completed a preliminary performance analysis of the SR-71 aircraft for use as a launch platform for high-speed research vehicles and for carrying captive experimental packages to high altitude and Mach number conditions. Externally mounted research platforms can significantly increase drag, limiting test time and, in extreme cases, prohibiting penetration through the high-drag, transonic flight regime. To provide supplemental SR-71 acceleration, methods have been developed that could increase the thrust of the J58 turbojet engines. These methods include temperature and speed increases and augmentor nitrous oxide injection. The thrust-enhanced engines would allow the SR-71 aircraft to carry higher drag research platforms than it could without enhancement. This paper presents predicted SR-71 performance with and without enhanced engines. A modified climb-dive technique is shown to reduce fuel consumption when flying through the transonic flight regime with a large external payload. Estimates are included of the maximum platform drag profiles with which the aircraft could still complete a high-speed research mission. In this case, enhancement was found to increase the SR-71 payload drag capability by 25 percent. The thrust enhancement techniques and performance prediction methodology are described.

Prediction of in-use emissions of heavy-duty diesel vehicles from engine testing.

PubMed

Yanowitz, Janet; Graboski, Michael S; McCormick, Robert L

2002-01-15

A model of a heavy-duty vehicle driveline with automatic transmission has been developed for estimating engine speed and load from vehicle speed. The model has been validated using emissions tests conducted on three diesel vehicles on a chassis dynamometer and then on the engines removed from the vehicles tested on an engine dynamometer. Nitrogen oxide (NOx) emissions were proportional to work done by the engine. For two of the engines, the NOx/horsepower(HP) ratio was the same on the engine and on the chassis dynamometer tests. For the third engine NOx/HP was significantly higher from the chassis test, possibly due to the use of dual engine maps. The engine certification test generated consistently less particulate matter emissions on a gram per brake horsepower-hour basis than the Heavy Duty Transient and Central Business District chassis cycles. A good linear correlation (r2 = 0.97 and 0.91) was found between rates of HP increase integrated over the test cycle and PM emissions for both the chassis and the engine tests for two of the vehicles. The model also shows how small changes in vehicle speeds can lead to a doubling of load on the engine. Additionally, the model showed that it is impossible to drive a vehicle cycle equivalent to the heavy-duty engine federal test procedure on these vehicles.

A Demonstration of a Retrofit Architecture for Intelligent Control and Diagnostics of a Turbofan Engine

NASA Technical Reports Server (NTRS)

Litt, Jonathan S.; Turso, James A.; Shah, Neerav; Sowers, T. Shane; Owen, A. Karl

2005-01-01

A retrofit architecture for intelligent turbofan engine control and diagnostics that changes the fan speed command to maintain thrust is proposed and its demonstration in a piloted flight simulator is described. The objective of the implementation is to increase the level of autonomy of the propulsion system, thereby reducing pilot workload in the presence of anomalies and engine degradation due to wear. The main functions of the architecture are to diagnose the cause of changes in the engine s operation, warning the pilot if necessary, and to adjust the outer loop control reference signal in response to the changes. This requires that the retrofit control architecture contain the capability to determine the changed relationship between fan speed and thrust, and the intelligence to recognize the cause of the change in order to correct it or warn the pilot. The proposed retrofit architecture is able to determine the fan speed setting through recognition of the degradation level of the engine, and it is able to identify specific faults and warn the pilot. In the flight simulator it was demonstrated that when degradation is introduced into an engine with standard fan speed control, the pilot needs to take corrective action to maintain heading. Utilizing the intelligent retrofit control architecture, the engine thrust is automatically adjusted to its expected value, eliminating yaw without pilot intervention.

Preliminary Data on the Effects of Inlet Pressure Distortions on the J57-P-1 Turbojet Engine

NASA Technical Reports Server (NTRS)

Wallner, Lewis E.; Lubick, Robert J.; Einstein, Thomas H.

1954-01-01

An investigation to determine the steady-state and surge characteristics of the J57-P-1 two-spool turbojet engine with various inlet air-flow distortions was conducted in the altitude wind tunnel at the NACA Lewis laboratory. Along with a uniform inlet total-pressure distribution, one circumferential and three radial pressure distortions were investigated. Data were obtained over a complete range of compressor speeds both with and without intercompressor air bleed at a flight Mach number of 0.8 and at altitudes of 35,000 and 50,000 feet. Total-pressure distortions of the magnitudes investigated had very little effect on the steady-state operating line for either the outer or inner compressor. The small radial distortions investigated also had engine over that obtained with the uniform inlet pressure distribution. The circumferential distortion, however, raised the minimum speed at which the engine could operate without encountering surge when the intercompressor bleeds were closed. This increase in minimum speed resulted in a substantial reduction in the operable speed range accompanied by a reduction in the altitude operating limit.

Acoustic characteristics of a large-scale wind tunnel model of an upper-surface blown flap transport having two engines

NASA Technical Reports Server (NTRS)

Falarski, M. D.; Aoyagi, K.; Koenig, D. G.

1973-01-01

The upper-surface blown (USB) flap as a powered-lift concept has evolved because of the potential acoustic shielding provided when turbofan engines are installed on a wing upper surface. The results from a wind tunnel investigation of a large-scale USB model powered by two JT15D-1 turbofan engines are-presented. The effects of coanda flap extent and deflection, forward speed, and exhaust nozzle configuration were investigated. To determine the wing shielding the acoustics of a single engine nacelle removed from the model were also measured. Effective shielding occurred in the aft underwing quadrant. In the forward quadrant the shielding of the high frequency noise was counteracted by an increase in the lower frequency wing-exhaust interaction noise. The fuselage provided shielding of the opposite engine noise such that the difference between single and double engine operation was 1.5 PNdB under the wing. The effects of coanda flap deflection and extent, angle of attack, and forward speed were small. Forward speed reduced the perceived noise level (PNL) by reducing the wing-exhaust interaction noise.

A Sequential Shifting Algorithm for Variable Rotor Speed Control

NASA Technical Reports Server (NTRS)

Litt, Jonathan S.; Edwards, Jason M.; DeCastro, Jonathan A.

2007-01-01

A proof of concept of a continuously variable rotor speed control methodology for rotorcraft is described. Variable rotor speed is desirable for several reasons including improved maneuverability, agility, and noise reduction. However, it has been difficult to implement because turboshaft engines are designed to operate within a narrow speed band, and a reliable drive train that can provide continuous power over a wide speed range does not exist. The new methodology proposed here is a sequential shifting control for twin-engine rotorcraft that coordinates the disengagement and engagement of the two turboshaft engines in such a way that the rotor speed may vary over a wide range, but the engines remain within their prescribed speed bands and provide continuous torque to the rotor; two multi-speed gearboxes facilitate the wide rotor speed variation. The shifting process begins when one engine slows down and disengages from the transmission by way of a standard freewheeling clutch mechanism; the other engine continues to apply torque to the rotor. Once one engine disengages, its gear shifts, the multi-speed gearbox output shaft speed resynchronizes and it re-engages. This process is then repeated with the other engine. By tailoring the sequential shifting, the rotor may perform large, rapid speed changes smoothly, as demonstrated in several examples. The emphasis of this effort is on the coordination and control aspects for proof of concept. The engines, rotor, and transmission are all simplified linear models, integrated to capture the basic dynamics of the problem.

40 CFR 1065.510 - Engine mapping.

Code of Federal Regulations, 2012 CFR

2012-07-01

... expected maximum power. Continue the warm-up until the engine coolant, block, or head absolute temperature... torque of zero on the engine's primary output shaft, and allow the engine to govern the speed. Measure... values. (ii) For engines without a low-speed governor, operate the engine at warm idle speed and zero...

40 CFR 1065.510 - Engine mapping.

Code of Federal Regulations, 2014 CFR

2014-07-01

... expected maximum power. Continue the warm-up until the engine coolant, block, or head absolute temperature... torque of zero on the engine's primary output shaft, and allow the engine to govern the speed. Measure... values. (ii) For engines without a low-speed governor, operate the engine at warm idle speed and zero...

40 CFR 1065.510 - Engine mapping.

Code of Federal Regulations, 2013 CFR

2013-07-01

... expected maximum power. Continue the warm-up until the engine coolant, block, or head absolute temperature... torque of zero on the engine's primary output shaft, and allow the engine to govern the speed. Measure... values. (ii) For engines without a low-speed governor, operate the engine at warm idle speed and zero...

Load-Speed Interaction Effects on the Biomechanics of Backpack Load Carriage

DTIC Science & Technology

2001-05-01

Duchenn muscular dystrophy . Developmental Med and Child Neurology, 23:3- 22, 1981. 39. Winter, D.A. Biomechanics of Human Movement. John Wiley & Sons, Inc...and C.J. De Luca. Muscle fatigue monitor: A noninvasive device for observing localized muscular fatigue. IEEE Transactions on Biomedical Engineering...joint forces, muscle torques, muscle electrical activity and backpack acceleration increased when speed andlor load increased, likely increasing the

The effects of engine speed and injection characteristics on the flow field and fuel/air mixing in motored two-stroke diesel engines

NASA Technical Reports Server (NTRS)

Nguyen, H. L.; Carpenter, M. H.; Ramos, J. I.

1987-01-01

A numerical analysis is presented on the effects of the engine speed, injection angle, droplet distribution function, and spray cone angle on the flow field, spray penetration and vaporization, and turbulence in a turbocharged motored two-stroke diesel engine. The results indicate that the spray penetration and vaporization, velocity, and turbulence kinetic energy increase with the intake swirl angle. Good spray penetration, vaporization, and mixing can be achieved by injecting droplets of diameters between 50 and 100 microns along a 120-deg cone at about 315 deg before top-dead-center for an intake swirl angle of 30 deg. The spray penetration and vaporization were found to be insensitive to the turbulence levels within the cylinder. The results have also indicated that squish is necessary in order to increase the fuel vaporization rate and mixing.

Operating Temperatures of a Sodium-Cooled Exhaust Valve as Measured by a Thermocouple

NASA Technical Reports Server (NTRS)

Sanders, J C; Wilsted, H D; Mulcahy, B A

1943-01-01

Report presents the results of a thermocouple installed in the crown of a sodium-cooled exhaust valve. The valve was tested in an air-cooled engine cylinder and valve temperatures under various engine operating conditions were determined. A temperature of 1337 degrees F. was observed at a fuel-air ratio of 0.064, a brake mean effective pressure of 179 pounds per square inch, and an engine speed of 2000 r.p.m. Fuel-air ratio was found to have a large influence on valve temperature, but cooling-air pressure and variation in spark advance had little effect. An increase in engine power by change of speed or mean effective pressure increased the valve temperature. It was found that the temperature of the rear-spark-plug bushing was not a satisfactory indication of the temperature of the exhaust valve.

Idling speed control system of an internal combustion engine

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

Miyazaki, M.; Ishii, M.; Kako, H.

1986-09-16

This patent describes an idling speed control system of an internal combustion engine comprising: a valve device which controls the amount of intake air for the engine; an actuator which includes an electric motor for variably controlling the opening of the value device; rotation speed detector means for detecting the rotation speed of the engine; idling condition detector means for detecting the idling condition of the engine; feedback control means responsive to the detected output of the idling condition detector means for generating feedback control pulses to intermittently drive the electric motor so that the detected rotation speed of themore » engine under the idling condition may converge into a target idling rotation speed; and control means responsive to the output of detector means that detects an abnormally low rotation speed of the engine detected by the rotation speed detector means for generating control pulses that do not overlap the feedback control pulses to drive the electric motor in a predetermined direction.« less

Effects of Fuel Composition on EGR Dilution Tolerance in Spark Ignited Engines

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

Szybist, James P

2016-01-01

Fuel-specific differences in exhaust gas recirculation (EGR) dilution tolerance are studied in a modern, direct-injection single-cylinder research engine. A total of 6 model fuel blends are examined at a constant research octane number (RON) of 95 using n-heptane, iso-octane, toluene, and ethanol. Laminar flame speeds for these mixtures, which were calculated two different methods (an energy fraction mixing rule and a detailed kinetic simulation), spanned a range of about 6 cm/s. A constant fueling nominal load of 350 kPa IMEPg at 2000 rpm was operated with varying CA50 from 8-20 CAD aTDCf, and with EGR increasing until a COV ofmore » IMEP of 5% is reached. The results illustrate that flame speed affects EGR dilution tolerance; fuels with increased flame speeds increase EGR tolerance. Specifically, flame speed correlates most closely to the initial flame kernel growth, measured as the time of ignition to 5% mass fraction burned. The effect of the latent heat of vaporization on the flame speed is taken into account for the ethanol-containing fuels. At a 30 vol% blend level, the increased enthalpy of vaporization of ethanol compared to conventional hydrocarbons can decrease the temperature at the time of ignition by a maximum of 15 C, which can account for up to a 3.5 cm/s decrease in flame speed. The ethanol-containing fuels, however, still exhibit a flame speed advantage, and a dilution tolerance advantage over the slower flame-speed fuels. The fuel-specific differences in dilution tolerance are significant at the condition examined, allowing for a 50% relative increase in EGR (4% absolute difference in EGR) at a constant COV of IMEP of 3%.« less

Nonlinear engine model for idle speed control

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

Livshiz, M.; Sanvido, D.J.; Stiles, S.D.

1994-12-31

This paper describes a nonlinear model of an engine used for the design of idle speed control and prediction in a broad range of idle speeds and operational conditions. Idle speed control systems make use of both spark advance and the idle air actuator to control engine speed for improved response relative to variations in the target idle speed due to load disturbances. The control system at idle can be presented by a multiple input multiple output (MIMO) nonlinear model. Information of nonlinearities helps to improve performance of the system over the whole range of engine speeds. A proposed simplemore » nonlinear model of the engine at idle was applied for design of optimal controllers and predictors for improved steady state, load rejection and transition from and to idle. This paper describes vehicle results of engine speed prediction based on the described model.« less

Spark ignition timing control system for internal combustion engine with feature of suppression of jerking during engine acceleration

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

Tomisawa, N.

1989-07-04

This patent describes a spark ignition timing control system for an internal combustion engine, it comprises: sensor means monitoring preselected parameters for producing a sensor signal; first means for deriving a spark ignition timing on the basis of data contained in the sensor signal; second means for detecting an engine acceleration demand for producing an accelerating condition indicative signal; and third means, responsive to the accelerating condition indicative signal, for modifying the spark ignition timing derived by the first means after expiration of a first predetermined period of time of occurence of the accelerating condition indicative signal, in such amore » manner that the spark ignition timing is advanced and retarded for suppressing cycle-to-cycle fluctuation of engine speed and for smoothly increasing engine speed.« less

A study on emission characteristics of an EFI engine with ethanol blended gasoline fuels

NASA Astrophysics Data System (ADS)

He, Bang-Quan; Wang, Jian-Xin; Hao, Ji-Ming; Yan, Xiao-Guang; Xiao, Jian-Hua

The effect of ethanol blended gasoline fuels on emissions and catalyst conversion efficiencies was investigated in a spark ignition engine with an electronic fuel injection (EFI) system. The addition of ethanol to gasoline fuel enhances the octane number of the blended fuels and changes distillation temperature. Ethanol can decrease engine-out regulated emissions. The fuel containing 30% ethanol by volume can drastically reduce engine-out total hydrocarbon emissions (THC) at operating conditions and engine-out THC, CO and NO x emissions at idle speed, but unburned ethanol and acetaldehyde emissions increase. Pt/Rh based three-way catalysts are effective in reducing acetaldehyde emissions, but the conversion of unburned ethanol is low. Tailpipe emissions of THC, CO and NO x have close relation to engine-out emissions, catalyst conversion efficiency, engine's speed and load, air/fuel equivalence ratio. Moreover, the blended fuels can decrease brake specific energy consumption.

A Mathematical Model of Marine Diesel Engine Speed Control System

NASA Astrophysics Data System (ADS)

Sinha, Rajendra Prasad; Balaji, Rajoo

2018-02-01

Diesel engine is inherently an unstable machine and requires a reliable control system to regulate its speed for safe and efficient operation. Also, the diesel engine may operate at fixed or variable speeds depending upon user's needs and accordingly the speed control system should have essential features to fulfil these requirements. This paper proposes a mathematical model of a marine diesel engine speed control system with droop governing function. The mathematical model includes static and dynamic characteristics of the control loop components. Model of static characteristic of the rotating fly weights speed sensing element provides an insight into the speed droop features of the speed controller. Because of big size and large time delay, the turbo charged diesel engine is represented as a first order system or sometimes even simplified to a pure integrator with constant gain which is considered acceptable in control literature. The proposed model is mathematically less complex and quick to use for preliminary analysis of the diesel engine speed controller performance.

ECN-15655

NASA Image and Video Library

1981-05-21

In this photograph, the C-140 JetStar is fitted with a model of a high-speed propeller. Three different designs were tested at NASA's Dryden Flight Research Facility in 1981-1982. Their swept-back blades were intended to increase the speed and fuel efficiency of turboprop aircraft. Speeds of Mach 0.8 were thought possible, while using 20 to 30 percent less fuel than standard jet engines.

Engine control system having speed-based timing

DOEpatents

Willi, Martin L [Dunlap, IL; Fiveland, Scott B [Metamora, IL; Montgomery, David T [Edelstein, IL; Gong, Weidong [Dunlap, IL

2012-02-14

A control system for an engine having a cylinder is disclosed having an engine valve movable to regulate a fluid flow of the cylinder and an actuator associated with the engine valve. The control system also has a controller in communication with the actuator. The controller is configured to receive a signal indicative of engine speed and compare the engine speed signal with a desired engine speed. The controller is also configured to selectively regulate the actuator to adjust a timing of the engine valve to control an amount of air/fuel mixture delivered to the cylinder based on the comparison.

14 CFR 23.33 - Propeller speed and pitch limits.

Code of Federal Regulations, 2014 CFR

2014-01-01

... the all engine(s) operating climb speed specified in § 23.65, the propeller must limit the engine r.p... approved overspeed, a means to limit the maximum engine and propeller speed to not more than the maximum... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Propeller speed and pitch limits. 23.33...

14 CFR 23.33 - Propeller speed and pitch limits.

Code of Federal Regulations, 2013 CFR

2013-01-01

... the all engine(s) operating climb speed specified in § 23.65, the propeller must limit the engine r.p... approved overspeed, a means to limit the maximum engine and propeller speed to not more than the maximum... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Propeller speed and pitch limits. 23.33...

14 CFR 23.33 - Propeller speed and pitch limits.

Code of Federal Regulations, 2012 CFR

2012-01-01

... the all engine(s) operating climb speed specified in § 23.65, the propeller must limit the engine r.p... approved overspeed, a means to limit the maximum engine and propeller speed to not more than the maximum... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Propeller speed and pitch limits. 23.33...

A Segmented Ion-Propulsion Engine

NASA Technical Reports Server (NTRS)

Brophy, John R.

1992-01-01

New design approach for high-power (100-kW class or greater) ion engines conceptually divides single engine into combination of smaller discharge chambers integrated to operate as single large engine. Analogous to multicylinder automobile engine, benefits include reduction in required accelerator system span-to-gap ratio for large-area engines, reduction in required hollow-cathode emission current, mitigation of plasma-uniformity problem, increased tolerance to accelerator system faults, and reduction in vacuum-system pumping speed.

Factorial analysis of diesel engine performance using different types of biofuels.

PubMed

Tashtoush, Ghassan M; Al-Widyan, Mohamad I; Albatayneh, Aiman M

2007-09-01

In this study, several bio-source-fuels like fresh and waste vegetable oil and waste animal fat were tested at different injector pressures (120, 140, 190, 210 bar) in a direct-injection, naturally aspirated, single-cylinder diesel engine with a design injection pressure of 190 bar. Using 2k factorial analysis, the effect of injection pressure (Pi) and fuel type on three engine parameters, namely, combustion efficiency (etac), mass fuel consumption (mf), and engine speed (N) was examined. It was found that Pi and fuel type significantly affected both etac and mf while they had a slight effect on engine speed. Moreover, with diesel and biodiesels, the etac increased to a maximum at 190 bar but declined at the higher Pi value. In contrast, higher Pi had a favorable effect on etac over the whole Pi range with all the other more viscous fuels tested. In addition, the mass fuel consumption consistently decreased with an increase in Pi for all the fuels including the baseline diesel fuel, with which the engine consistently attained higher etac and higher rpm compared to all the other fuels tested.

Relative Economy of Different Methods of Airplane Construction

NASA Technical Reports Server (NTRS)

Herrmann, H

1931-01-01

A comparison of the relative economy of airplane construction shows that monoplanes are cheaper than biplanes; that all-metal construction is much more expensive than mixed construction; that multi-engine airplanes are more expensive than single-engine types of the same carrying capacity and speed;that the cost of airplanes is materially reduced by increasing their size without increasing the number of engines. The greatest economy usually coincides with the best aerodynamic and static conditions and the cost is always increased by safety requirements.

The Effects of Engine Speed and Mixture Temperature on the Knocking Characteristics of Several Fuels

NASA Technical Reports Server (NTRS)

Lee, Dana W

1940-01-01

Six 100-octane and two 87-octane aviation engine fuels were tested in a modified C.F.R. variable-compression engine at 1,500, 2,000 and 2,500 rpm. The mixture temperature was raised from 50 to 300 F in approximately 50 degree steps and, at each temperature, the compression ratio was adjusted to give incipient knock as shown by a cathode ray indicator. The results are presented in tabular form. The results are analyzed on the assumption that the conditions which determine whether a given fuel will knock are the maximum values of density and temperature reached by the burning gases. A maximum permissible density factor, proportional to the maximum density of the burning gases just prior to incipient knock, and the temperature of the burning gases at that time were computed for each of the test conditions. Values of the density factors were plotted against the corresponding end-gas temperatures for the three engine speeds and also against engine speed for several and end-gas temperatures. The maximum permissible density factor varied only slightly with engine speed but decreased rapidly with an increase in the end-gas temperature. The effect of changing the mixture temperature was different for fuels of different types. The results emphasize the desirability of determining the anti knock values of fuels over a wide range of engine and intake-air conditions rather that at a single set of conditions.

Rotordynamic Feasibility of a Conceptual Variable-Speed Power Turbine Propulsion System for Large Civil Tilt-Rotor Applications

NASA Technical Reports Server (NTRS)

Howard, Samuel

2012-01-01

A variable-speed power turbine concept is analyzed for rotordynamic feasibility in a Large Civil Tilt-Rotor (LCTR) class engine. Implementation of a variable-speed power turbine in a rotorcraft engine would enable high efficiency propulsion at the high forward velocities anticipated of large tilt-rotor vehicles. Therefore, rotordynamics is a critical issue for this engine concept. A preliminary feasibility study is presented herein to address this concern and identify if variable-speed is possible in a conceptual engine sized for the LCTR. The analysis considers critical speed placement in the operating speed envelope, stability analysis up to the maximum anticipated operating speed, and potential unbalance response amplitudes to determine that a variable-speed power turbine is likely to be challenging, but not impossible to achieve in a tilt-rotor propulsion engine.

49 CFR 571.104 - Standard No. 104; Windshield wiping and washing systems.

Code of Federal Regulations, 2011 CFR

2011-10-01

... difference between one-half of the shoulder room dimension and the steering wheel centerline-to-car... frequency or speed shall be at least 45 cycles per minute regardless of engine load and engine speed. S4.1.1.3Regardless of engine speed and engine load, the highest and one lower frequency or speed shall differ by at...

Charge control microcomputer device for vehicles

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

Morishita, M.; Kouge, S.

1986-10-14

This patent describes a charge control microcomputer device for a vehicle, comprising: speed changing means for transmitting the output torque of an engine. The speed changing means includes a slip clutch means having an output with a variable slippage amount with respect to its input and controlled in accordance with an operating instruction. The speed changing means further includes a speed change gear for changing the rotational speed input thereto at an output thereto, the speed change gear receiving the output of the slip clutch means; a charging generator driven by the output of the speed change gear; a batterymore » charged by an output voltage of the charging generator; a voltage regulator for controlling the output voltage of the charging generator to a predetermined value; an engine controlling microcomputer for receiving data from the engine, to control the engine, the engine data comprising at least an engine speed signal; a charge control microcomputer for processing engine data from the engine controlling microcomputer and charge system data including terminal voltage data from the battery and generated voltage data from the changing generator; and a display unit for displaying detection data, including fault detection data, form the charge control microcomputer.« less

14 CFR 23.33 - Propeller speed and pitch limits.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Propeller speed and pitch limits. 23.33... Propeller speed and pitch limits. (a) General. The propeller speed and pitch must be limited to values that... the all engine(s) operating climb speed specified in § 23.65, the propeller must limit the engine r.p...

14 CFR 23.33 - Propeller speed and pitch limits.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Propeller speed and pitch limits. 23.33... Propeller speed and pitch limits. (a) General. The propeller speed and pitch must be limited to values that... the all engine(s) operating climb speed specified in § 23.65, the propeller must limit the engine r.p...

Filter-based control of particulate matter from a lean gasoline direct injection engine

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

Parks, II, James E; Lewis Sr, Samuel Arthur; DeBusk, Melanie Moses

New regulations requiring increases in vehicle fuel economy are challenging automotive manufacturers to identify fuel-efficient engines for future vehicles. Lean gasoline direct injection (GDI) engines offer significant increases in fuel efficiency over the more common stoichiometric GDI engines already in the marketplace. However, particulate matter (PM) emissions from lean GDI engines, particularly during stratified combustion modes, are problematic for lean GDI technology to meet U.S. Environmental Protection Agency Tier 3 and other future emission regulations. As such, the control of lean GDI PM with wall-flow filters, referred to as gasoline particulate filter (GPF) technology, is of interest. Since lean GDImore » PM chemistry and morphology differ from diesel PM (where more filtration experience exists), the functionality of GPFs needs to be studied to determine the operating conditions suitable for efficient PM removal. In addition, lean GDI engine exhaust temperatures are generally higher than diesel engines which results in more continuous regeneration of the GPF and less presence of the soot cake layer common to diesel particulate filters. Since the soot layer improves filtration efficiency, this distinction is important to consider. Research on the emission control of PM from a lean GDI engine with a GPF was conducted on an engine dynamometer. PM, after dilution, was characterized with membrane filters, organic vs. elemental carbon characterization, and size distribution techniques at various steady state engine speed and load points. The engine was operated in three primary combustion modes: stoichiometric, lean homogeneous, and lean stratified. In addition, rich combustion was utilized to simulate PM from engine operation during active regeneration of lean NOx control technologies. High (>95%) PM filtration efficiencies were observed over a wide range of conditions; however, some PM was observed to slip through the GPF at high speed and load conditions. The PM characterization at various engine speeds and loads will help enable optimized GPF design and control to achieve more fuel efficient lean GDI vehicles with low PM emissions.« less

Performance Investigations of a Large Centrifugal Compressor from an Experimental Turbojet Engine

NASA Technical Reports Server (NTRS)

Ginsburg, Ambrose; Creagh, John W. R.; Ritter, William K.

1948-01-01

An investigation was conducted on a large centrifugal compressor from an experimental turbojet engine to determine the performance of the compressor and to obtain fundamental information on the aerodynamic problems associated with large centrifugal-type compressors. The results of the research conducted on the compressor indicated that the compressor would not meet the desired engine-design air-flow requirements (78 lb/sec) because of an air-flow restriction in the vaned collector (diffuser). Revision of the vaned collector resulted in an increased air-flow capacity over the speed range and showed improved matching of the impeller and diffuser components. At maximum flow, the original compressor utilized approximately 90 percent of the available geometric throat area at the vaned-collector inlet and the revised compressor utilized approximately 94 percent, regardless of impeller speed. The ratio of the maximum weight flows of the revised and original compressors were less than the ratio of effective critical throat areas of the two compressors because of the large pressure losses in the impeller near the impeller inelt and the difference increased with an increase in impeller speed. In order to further increase the pressure ratio and maximum weight flow of the compressor, the impeller must be modified to eliminate the pressure losses therein.

A New, Highly Improved Two-Cycle Engine

NASA Technical Reports Server (NTRS)

Wiesen, Bernard

2008-01-01

The figure presents a cross-sectional view of a supercharged, variable-compression, two-cycle, internal-combustion engine that offers significant advantages over prior such engines. The improvements are embodied in a combination of design changes that contribute synergistically to improvements in performance and economy. Although the combination of design changes and the principles underlying them are complex, one of the main effects of the changes on the overall engine design is reduced (relative to prior two-cycle designs) mechanical complexity, which translates directly to reduced manufacturing cost and increased reliability. Other benefits include increases in the efficiency of both scavenging and supercharging. The improvements retain the simplicity and other advantages of two-cycle engines while affording increases in volumetric efficiency and performance across a wide range of operating conditions that, heretofore have been accessible to four-cycle engines but not to conventionally scavenged two-cycle ones, thereby increasing the range of usefulness of the two-cycle engine into all areas now dominated by the four-cycle engine. The design changes and benefits are too numerous to describe here in detail, but it is possible to summarize the major improvements: Reciprocating Shuttle Inlet Valve The entire reciprocating shuttle inlet valve and its operating gear is constructed as a single member. The shuttle valve is actuated in a lost-motion arrangement in which, at the ends of its stroke, projections on the shuttle valve come to rest against abutments at the ends of grooves in a piston skirt. This shuttle-valve design obviates the customary complex valve mechanism, actuated from an engine crankshaft or camshaft, yet it is effective with every type of two-cycle engine, from small high-speed single cylinder model engines, to large low-speed multiple cylinder engines.

49 CFR 571.104 - Standard No. 104; Windshield wiping and washing systems.

Code of Federal Regulations, 2014 CFR

2014-10-01

... outboard of the steering wheel centerline 0.15 times the difference between one-half of the shoulder room... frequency or speed shall be at least 45 cycles per minute regardless of engine load and engine speed. S4.1.1.3Regardless of engine speed and engine load, the highest and one lower frequency or speed shall differ by at...

Research of rotating machinery vibration parameters - Shaft speed relationship

NASA Astrophysics Data System (ADS)

Kostyukov, V. N.; Kostyukov, A. V.; Zaytsev, A. V.; Teterin, A. O.

2017-08-01

The paper considers the relationship between the parameters of the vibration arising in rotating machinery during operation and the shaft speed. The goal of this paper is to determine the dependence of the vibration parameters on the shaft speed for solving applied engineering problems. To properly evaluate the technical condition of bearing assemblies, we should take into account the pattern of the rotating machinery vibration parameters-shaft speed relationship, which will allow creating new diagnostic features, the totality of which will ensure an increased reliability of diagnosis. We took the check for a correlation between the factor and resultative feature parameters as the correlation analysis method. A high pair linear correlation between the diagnostic features (acceleration, velocity, displacement) and the shaft speed was determined on the basis of the check for correlation between the vibration parameters and the shaft speed, and also the linear correlation coefficients can be used to solve the applied engineering problems of diagnosing the bearing assemblies of the rotating machinery.

Research on H2 speed governor for diesel engine of marine power station

NASA Astrophysics Data System (ADS)

Huang, Man-Lei

2007-09-01

The frequency stability of a marine power system is determined by the dynamic characteristic of the diesel engine speed regulation system in a marine power station. In order to reduce the effect of load disturbances and improve the dynamic precision of a diesel engine speed governor, a controller was designed for a diesel engine speed regulation system using H2 control theory. This transforms the specifications of the system into a standard H2 control problem. Firstly, the mathematical model of a diesel engine speed regulation system using an H2 speed governor is presented. To counter external disturbances and model uncertainty, the design of an H2 speed governor rests on the problem of mixed sensitivity. Computer simulation verified that the H2 speed governor improves the dynamic precision of a system and the ability to adapt to load disturbances, thus enhancing the frequency stability of marine power systems.

Idle speed and fuel vapor recovery control system

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

Orzel, D.V.

1993-06-01

A method for controlling idling speed of an engine via bypass throttle connected in parallel to a primary engine throttle and for controlling purge flow through a vapor recovery system into an air/fuel intake of the engine is described, comprising the steps of: positioning the bypass throttle to decrease any difference between a desired engine idle speed and actual engine idle speed; and decreasing the purge flow when said bypass throttle position is less than a preselected fraction of a maximum bypass throttle position.

40 CFR Appendix II to Part 1039 - Steady-State Duty Cycles

Code of Federal Regulations, 2011 CFR

2011-07-01

... Appendix II to Part 1039—Steady-State Duty Cycles (a) The following duty cycles apply for constant-speed engines: (1) The following duty cycle applies for discrete-mode testing: D2 mode number Engine speed...(seconds) Engine speed Torque(percent) 1, 2 1a Steady-state 53 Engine governed 100. 1b Transition 20 Engine...

Altitude Performance of Modified J71 Afterburner with Revised Engine Operating Conditions

NASA Technical Reports Server (NTRS)

Useller, James W.; Russey, Robert E.

1955-01-01

An investigation was conducted in an altitude test chamber at the NACA Lewis laboratory to determine the effect of a revision of the rated engine operating conditions and modifications to the afterburner fue1 system, flameholder, and shell cooling on the augmented performance of the J71-A-2 (x-29) turbo jet engine operating at altitude . The afterburner modifications were made by the manufacturer to improve the endurance at sea-level, high-pressure conditions and to reduce the afterburner shell temperatures. The engine operating conditions of rated rotational speed and turbine-outlet gas temperature were increased. Data were obtained at conditions simulating flight at a Mach number of 0.9 and at altitudes from 40,000 to 60,000 feet. The afterburner modifications caused a reduction in afterburner combustion efficiency. The increase in rated engine speed and turbine-outlet temperature coupled with the afterburner modifications resulted in the over-all thrust of the engine and afterburner being unchanged at a given afterburner equivalence ratio, while the specific fuel consumption was increased slightly. A moderate shift in the range of equivalence ratios over which the afterburner would operate was encountered, but the maximum operable altitude remained unaltered. The afterburner-shell temperatures were also slightly reduced because of the modifications to the afterburner.

Feasibility of magnetic bearings for advanced gas turbine engines

NASA Technical Reports Server (NTRS)

Hibner, David; Rosado, Lewis

1992-01-01

The application of active magnetic bearings to advanced gas turbine engines will provide a product with major improvements compared to current oil lubricated bearing designs. A rethinking of the engine rotating and static structure design is necessary and will provide the designer with significantly more freedom to meet the demanding goals of improved performance, increased durability, higher reliability, and increased thrust to weight ratio via engine weight reduction. The product specific technology necessary for this high speed, high temperature, dynamically complex application has been defined. The resulting benefits from this approach to aircraft engine rotor support and the complementary engine changes and improvements have been assessed.

The Effect of Modified Control Limits on the Performance of a Generic Commercial Aircraft Engine

NASA Technical Reports Server (NTRS)

Csank, Jeffrey T.; May, Ryan D.; Gou, Ten-Huei; Litt, Jonathan S.

2012-01-01

This paper studies the effect of modifying the control limits of an aircraft engine to obtain additional performance. In an emergency situation, the ability to operate an engine above its normal operating limits and thereby gain additional performance may aid in the recovery of a distressed aircraft. However, the modification of an engine s limits is complex due to the risk of an engine failure. This paper focuses on the tradeoff between enhanced performance and risk of either incurring a mechanical engine failure or compromising engine operability. The ultimate goal is to increase the engine performance, without a large increase in risk of an engine failure, in order to increase the probability of recovering the distressed aircraft. The control limit modifications proposed are to extend the rotor speeds, temperatures, and pressures to allow more thrust to be produced by the engine, or to increase the rotor accelerations and allow the engine to follow a fast transient. These modifications do result in increased performance; however this study indicates that these modifications also lead to an increased risk of engine failure.

Acoustic measurements for the combustion diagnosis of diesel engines fuelled with biodiesels

NASA Astrophysics Data System (ADS)

Zhen, Dong; Wang, Tie; Gu, Fengshou; Tesfa, Belachew; Ball, Andrew

2013-05-01

In this paper, an experimental investigation was carried out on the combustion process of a compression ignition (CI) engine running with biodiesel blends under steady state operating conditions. The effects of biodiesel on the combustion process and engine dynamics were analysed for non-intrusive combustion diagnosis based on a four-cylinder, four-stroke, direct injection and turbocharged diesel engine. The signals of vibration, acoustic and in-cylinder pressure were measured simultaneously to find their inter-connection for diagnostic feature extraction. It was found that the sound energy level increases with the increase of engine load and speed, and the sound characteristics are closely correlated with the variation of in-cylinder pressure and combustion process. The continuous wavelet transform (CWT) was employed to analyse the non-stationary nature of engine noise in a higher frequency range. Before the wavelet analysis, time synchronous average (TSA) was used to enhance the signal-to-noise ratio (SNR) of the acoustic signal by suppressing the components which are asynchronous. Based on the root mean square (RMS) values of CWT coefficients, the effects of biodiesel fractions and operating conditions (speed and load) on combustion process and engine dynamics were investigated. The result leads to the potential of airborne acoustic measurements and analysis for engine condition monitoring and fuel quality evaluation.

Compression-ignition engine performance with undoped and doped fuel oils and alcohol mixtures

NASA Technical Reports Server (NTRS)

Moore, Charles S; Foster, Hampton H

1939-01-01

Several fuel oils, doped fuel oils, and mixtures of alcohol and fuel oil were tested in a high-speed, single-cylinder, compression-ignition engine to determine power output, fuel consumption, and ignition and combustion characteristics. Fuel oils or doped fuel oils of high octane number had shorter ignition lags, lower rates of pressure rise, and gave smoother engine operation than fuel oils or doped fuel oils of low octane number. Higher engine rotative speeds and boost pressures resulted in smoother engine operation and permitted the use of fuel oils of relatively low octane number. Although the addition of a dope to a fuel oil decreased the ignition lag and the rate of pressure rise, the ensuing rate of combustion was somewhat slower than for the undoped fuel oil so that the effectiveness of combustion was practically unchanged. Alcohol used as an auxiliary fuel, either as a mixture or by separate injection, increased the rates of pressure rise and induced roughness. In general, the power output decreased as the proportion of alcohol increased and, below maximum power, varied with the heating value of the total fuel charge.

Development of high-speed rolling-element bearings. A historical and technical perspective

NASA Technical Reports Server (NTRS)

Zaretsky, E. V.

1982-01-01

Research on large-bore ball and roller bearings for aircraft engines is described. Tapered roller bearings and small-bore bearings are discussed. Temperature capabilities of rolling element bearings for aircraft engines have moved from 450 to 589 K (350 to 600 F) with increased reliability. High bearing speeds to 3 million DN can be achieved with a reliability exceeding that which was common in commercial aircraft. Capabilities of available bearing steels and lubricants were defined and established. Computer programs for the analysis and design of rolling element bearings were developed and experimentally verified. The reported work is a summary of NASA contributions to high performance engine and transmission bearing capabilities.

Lean burn natural gas fueled S.I. engine and exhaust emissions

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

Varde, K.S.; Patro, N.; Drouillard, K.

1995-12-31

An experimental study was undertaken to study exhaust emission from a lean-burn natural gas spark ignition engine. The possibility that such an engine may help to reduce exhaust emissions substantially by taking advantage of natural gas fuel properties, such as its antiknock properties and extended lean flammability limit compared to gasoline, was the main motivation behind the investigation. A four cylinder, automotive type spark ignition engine was used in the investigation. The engine was converted to operate on natural gas by replacing its fuel system with a gaseous carburetion system. A 3-way metal metrix catalytic converter was used in themore » engine exhaust system to reduce emission levels. The engine operated satisfactorily at an equivalence ratio as lean as 0.6, at all speeds and loads. As a result NOx emissions were significantly reduced. However, hydrocarbon emissions were high, particularly at very lean conditions and light loads. Most of these hydrocarbons were made up of methane with small concentrations of ethane and propane. Coefficient of variations in hydrocarbons were generally high at very lean operating conditions and light loads, but decreased with increasing equivalence ratio and engine speed. Methane concentrations in the engine exhaust decreased with increasing load and equivalence ratio. At lean air-to-fuel ratios and light loads oxidation of methane in the catalyst was substantially limited and no NOx reduction was achieved. In addition, the proportion of nitric oxide in oxides of nitrogen increased with increasing amount of NOx in the engine exhaust. A major problem encountered in the study was the inability of the fuel system to maintain near constant air-to-fuel ratios at steady operating conditions.« less

Investigation of frequency-response characteristics of engine speed for a typical turbine-propeller engine

NASA Technical Reports Server (NTRS)

Taylor, Burt L , III; Oppenheimer, Frank L

1951-01-01

Experimental frequency-response characteristics of engine speed for a typical turbine-propeller engine are presented. These data were obtained by subjecting the engine to sinusoidal variations of fuel flow and propeller-blade-angle inputs. Correlation is made between these experimental data and analytical frequency-response characteristics obtained from a linear differential equation derived from steady-state torque-speed relations.

The application of LQR synthesis techniques to the turboshaft engine control problem

NASA Technical Reports Server (NTRS)

Pfeil, W. H.; De Los Reyes, G.; Bobula, G. A.

1984-01-01

A power turbine governor was designed for a recent-technology turboshaft engine coupled to a modern, articulated rotor system using Linear Quadratic Regulator (LQR) and Kalman Filter (KF) techniques. A linear, state-space model of the engine and rotor system was derived for six engine power settings from flight idle to maximum continuous. An integrator was appended to the fuel flow input to reduce the steady-state governor error to zero. Feedback gains were calculated for the system states at each power setting using the LQR technique. The main rotor tip speed state is not measurable, so a Kalman Filter of the rotor was used to estimate this state. The crossover of the system was increased to 10 rad/s compared to 2 rad/sec for a current governor. Initial computer simulations with a nonlinear engine model indicate a significant decrease in power turbine speed variation with the LQR governor compared to a conventional governor.

Diesel engine torsional vibration control coupling with speed control system

NASA Astrophysics Data System (ADS)

Guo, Yibin; Li, Wanyou; Yu, Shuwen; Han, Xiao; Yuan, Yunbo; Wang, Zhipeng; Ma, Xiuzhen

2017-09-01

The coupling problems between shafting torsional vibration and speed control system of diesel engine are very common. Neglecting the coupling problems sometimes lead to serious oscillation and vibration during the operation of engines. For example, during the propulsion shafting operation of a diesel engine, the oscillation of engine speed and the severe vibration of gear box occur which cause the engine is unable to operate. To find the cause of the malfunctions, a simulation model coupling the speed control system with the torsional vibration of deformable shafting is proposed and investigated. In the coupling model, the shafting is simplified to be a deformable one which consists of several inertias and shaft sections and with characteristics of torsional vibration. The results of instantaneous rotation speed from this proposed model agree with the test results very well and are successful in reflecting the real oscillation state of the engine operation. Furthermore, using the proposed model, the speed control parameters can be tuned up to predict the diesel engine a stable and safe running. The results from the tests on the diesel engine with a set of tuned control parameters are consistent with the simulation results very well.

Research on fuzzy PID control to electronic speed regulator

NASA Astrophysics Data System (ADS)

Xu, Xiao-gang; Chen, Xue-hui; Zheng, Sheng-guo

2007-12-01

As an important part of diesel engine, the speed regulator plays an important role in stabilizing speed and improving engine's performance. Because there are so many model parameters of diesel-engine considered in traditional PID control and these parameters present non-linear characteristic.The method to adjust engine speed using traditional PID is not considered as a best way. Especially for the diesel-engine generator set. In this paper, the Fuzzy PID control strategy is proposed. Some problems about its utilization in electronic speed regulator are discussed. A mathematical model of electric control system for diesel-engine generator set is established and the way of the PID parameters in the model to affect the function of system is analyzed. And then it is proposed the differential coefficient must be applied in control design for reducing dynamic deviation of system and adjusting time. Based on the control theory, a study combined control with PID calculation together for turning fuzzy PID parameter is implemented. And also a simulation experiment about electronic speed regulator system was conducted using Matlab/Simulink and the Fuzzy-Toolbox. Compared with the traditional PID Algorithm, the simulated results presented obvious improvements in the instantaneous speed governing rate and steady state speed governing rate of diesel-engine generator set when the fuzzy logic control strategy used.

Multiroller traction drive speed reducer: Evaluation for automotive gas turbine engine

NASA Technical Reports Server (NTRS)

Rohn, D. A.; Anderson, N. E.; Loewenthal, S. H.

1982-01-01

Tests were conducted on a nominal 14:1 fixed-ratio Nasvytis multiroller traction drive retrofitted as the speed reducer in an automotive gas turbine engine. Power turbine speeds of 45,000 rpm and a drive output power of 102 kW (137 hp) were reached. The drive operated under both variable roller loading (proportional to torque) and fixed roller loading (automatic loading mechanism locked). The drive operated smoothly and efficiently as the engine speed reducer. Engine specific fuel consumption with the traction speed reducer was comparable to that with the original helical gearset.

Studying the Transient Thermal Contact Conductance Between the Exhaust Valve and Its Seat Using the Inverse Method

NASA Astrophysics Data System (ADS)

Nezhad, Mohsen Motahari; Shojaeefard, Mohammad Hassan; Shahraki, Saeid

2016-02-01

In this study, the experiments aimed at analyzing thermally the exhaust valve in an air-cooled internal combustion engine and estimating the thermal contact conductance in fixed and periodic contacts. Due to the nature of internal combustion engines, the duration of contact between the valve and its seat is too short, and much time is needed to reach the quasi-steady state in the periodic contact between the exhaust valve and its seat. Using the methods of linear extrapolation and the inverse solution, the surface contact temperatures and the fixed and periodic thermal contact conductance were calculated. The results of linear extrapolation and inverse methods have similar trends, and based on the error analysis, they are accurate enough to estimate the thermal contact conductance. Moreover, due to the error analysis, a linear extrapolation method using inverse ratio is preferred. The effects of pressure, contact frequency, heat flux, and cooling air speed on thermal contact conductance have been investigated. The results show that by increasing the contact pressure the thermal contact conductance increases substantially. In addition, by increasing the engine speed the thermal contact conductance decreases. On the other hand, by boosting the air speed the thermal contact conductance increases, and by raising the heat flux the thermal contact conductance reduces. The average calculated error equals to 12.9 %.

Quiet Clean Short-haul Experimental Engine (QCSEE) main reduction gears test program

NASA Technical Reports Server (NTRS)

Misel, O. W.

1977-01-01

Sets of under the wing (UTW) engine reduction gears and sets of over the wing (OTW) engine reduction gears were fabricated for rig testing and subsequent installation in engines. The UTW engine reduction gears which have a ratio of 2.465:1 and a design rating of 9712 kW at 3157 rpm fan speed were operated at up to 105% speed at 60% torque and 100% speed at 125% torque. The OTW engine reduction gears which have a ratio of 2.062:1 and a design rating of 12,615 kW at 3861 rpm fan speed were operated at up to 95% speed at 50% torque and 80% speed at 109% torque. Satisfactory operation was demonstrated at powers up to 12,172 kW, mechanical efficiency up to 99.1% UTW, and a maximum gear pitch line velocity of 112 m/s (22,300 fpm) with a corresponding star gear spherical roller bearing DN of 850,00 OTW. Oil and star gear bearing temperatures, oil churning, heat rejection, and vibratory characteristics were acceptable for engine installation.

An experimental and modeling study investigating the ignition delay in a military diesel engine running hexadecane (cetane) fuel

DOE PAGES

Cowart, Jim S.; Fischer, Warren P.; Hamilton, Leonard J.; ...

2013-02-01

In an effort aimed at predicting the combustion behavior of a new fuel in a conventional diesel engine, cetane (n-hexadecane) fuel was used in a military engine across the entire speed–load operating range. The ignition delay was characterized for this fuel at each operating condition. A chemical ignition delay was also predicted across the speed–load range using a detailed chemical kinetic mechanism with a constant pressure reactor model. At each operating condition, the measured in-cylinder pressure and predicted temperature at the start of injection were applied to the detailed n-hexadecane kinetic mechanism, and the chemical ignition delay was predicted withoutmore » any kinetic mechanism calibration. The modeling results show that fuel–air parcels developed from the diesel spray with an equivalence ratio of 4 are the first to ignite. The chemical ignition delay results also showed decreasing igntion delays with increasing engine load and speed, just as the experimental data revealed. At lower engine speeds and loads, the kinetic modeling results show the characteristic two-stage negative temperature coefficient behavior of hydrocarbon fuels. However, at high engine speeds and loads, the reactions do not display negative temperature coefficient behavior, as the reactions proceed directly into high-temperature pathways due to higher temperatures and pressure at injection. A moderate difference between the total and chemical ignition delays was then characterized as a phyical delay period that scales inversely with engine speed. This physical delay time is representative of the diesel spray development time and is seen to become a minority fraction of the total igntion delay at higher engine speeds. In addition, the approach used in this study suggests that the ignition delay and thus start of combustion may be predicted with reasonable accuracy using kinetic modeling to determine the chemical igntion delay. Then, in conjunction with the physical delay time (experimental or modeling based), a new fuel’s acceptability in a conventional engine could be assessed by determining that the total ignition delay is not too short or too long.« less

The comparative performance of Roots type aircraft engine superchargers as affected by change in impeller speed and displacement

NASA Technical Reports Server (NTRS)

Ware, Marsden; Wilson, Ernest E

1929-01-01

This report presents the results of tests made on three sizes of roots type aircraft engine superchargers. The impeller contours and diameters of these machines were the same, but the length were 11, 8 1/4, and 4 inches, giving displacements of 0.509, 0.382, and 0.185 cubic foot per impeller revolution. The information obtained serves as a basis for the examination of the individual effects of impeller speed and displacement on performance and of the comparative performance when speed and displacement are altered simultaneously to meet definite service requirements. According to simple theory, when assuming no losses, the air weight handled and the power required for a given pressure difference are directly proportional to the speed and the displacement. These simple relations are altered considerably by the losses. When comparing the performance of different sizes of machines whose impeller speeds are so related that the same service requirements are met, it is found that the individual effects of speed and displacement are canceled to a large extent, and the only considerable difference is the difference in the power losses which decrease with increase in the displacement and the accompanying decrease in speed. This difference is small in relation to the net power of the engine supercharger unit, so that a supercharger with short impellers may be used in those applications where the space available is very limited with any considerable sacrifice in performance.

Aircraft turbofans: new economic and environmental benefits

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

Sampl, F.R.; Shank, M.E.

1985-09-01

This article describes turbofan and turboprop engines. Advanced turbofans and turboprop engines, by continuing to reduce the velocities of the jet exhaust and fan tip speed, can provide significant noise reductions. New combustors incorporated into these engines have reduced smoke, hydrocarbons and carbon monoxide to levels below the current requirements. The third generation of turbofans will continue to increase fuel efficiency and reduce aircraft operating costs. They are more modular in design and consist of half as many parts as the earlier engines, reducing maintenance time by half. Some of the key features of the new turbofan concept include: amore » very high bypass ratio/compression ratio cycle; swept fan blades; a thin, low-loss nacelle; low-loss reduction gearing; new materials; advanced compressor/turbine airfoils; and high-speed rotors with improved clearance control.« less

Influence of several factors on ignition lag in a compression-ignition engine

NASA Technical Reports Server (NTRS)

Gerrish, Harold C; Voss, Fred

1932-01-01

This investigation was made to determine the influence of fuel quality, injection advance angle, injection valve-opening pressure, inlet-air pressure, compression ratio, and engine speed on the time lag of auto-ignition of a Diesel fuel oil in a single-cylinder compression-ignition engine as obtained from an analysis of indicator diagrams. Three cam-operated fuel-injection pumps, two pumps cams, and an automatic injection valve with two different nozzles were used. Ignition lag was considered to be the interval between the start of injection of the fuel as determined with a Stroborama and the start of effective combustion as determined from the indicator diagram, the latter being the point where 4.0 x 10(exp-6) pound of fuel had been effectively burned. For this particular engine and fuel it was found that: (1) for a constant start and the same rate of fuel injection up the point of cut-off, a variation in fuel quantity from 1.2 x 10(exp-4) to 4.1 x 10(exp-4) pound per cycle has no appreciable effect on the ignition lag; (2) injection advance angle increases or decreases the lag according to whether density, temperature, or turbulence has the controlling influence; (3) increase in valve-opening pressure slightly increases the lag; and (4) increase of inlet-air pressure, compression ratio, and engine speed reduces the lag.

Windage Power Loss in Gas Foil Bearings and the Rotor-Stator Clearance of High Speed Generators Operating in High Pressure Environments

NASA Technical Reports Server (NTRS)

Bruckner, Robert J.

2009-01-01

Closed Brayton Cycle (CBC) and Closed Supercritical Cycle (CSC) engines are prime candidates to convert heat from a reactor into electric power for robotic space exploration and habitation. These engine concepts incorporate a permanent magnet starter/generator mounted on the engine shaft along with the requisite turbomachinery. Successful completion of the long-duration missions currently anticipated for these engines will require designs that adequately address all losses within the machine. The preliminary thermal management concept for these engine types is to use the cycle working fluid to provide the required cooling. In addition to providing cooling, the working fluid will also serve as the bearing lubricant. Additional requirements, due to the unique application of these microturbines, are zero contamination of the working fluid and entirely maintenance-free operation for many years. Losses in the gas foil bearings and within the rotor-stator gap of the generator become increasingly important as both rotational speed and mean operating pressure are increased. This paper presents the results of an experimental study, which obtained direct torque measurements on gas foil bearings and generator rotor-stator gaps. Test conditions for these measurements included rotational speeds up to 42,000 revolutions per minute, pressures up to 45 atmospheres, and test gases of nitrogen, helium, and carbon dioxide. These conditions provided a maximum test Taylor number of nearly one million. The results show an exponential rise in power loss as mean operating density is increased for both the gas foil bearing and generator windage. These typical "secondary" losses can become larger than the total system output power if conventional design paradigms are followed. A nondimensional analysis is presented to extend the experimental results into the CSC range for the generator windage.

14 CFR 23.49 - Stalling period.

Code of Federal Regulations, 2011 CFR

2011-01-01

... on the stalling speed, with engine(s) idling and throttle(s) closed; (3) The propeller(s) in the... which the airplane is controllable with— (1) For reciprocating engine-powered airplanes, the engine(s... more than 110 percent of the stalling speed; (2) For turbine engine-powered airplanes, the propulsive...

Very High Fuel Economy, Heavy Duty, Constant Speed, Truck Engine Optimized Via Unique Energy Recovery Turbines and Facilitated High Efficiency Continuously Variable Drivetrain

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

Bahman Habibzadeh

2010-01-31

The project began under a corporative agreement between Mack Trucks, Inc and the Department of Energy starting from September 1, 2005. The major objective of the four year project is to demonstrate a 10% efficiency gain by operating a Volvo 13 Litre heavy-duty diesel engine at a constant or narrow speed and coupled to a continuously variable transmission. The simulation work on the Constant Speed Engine started on October 1st. The initial simulations are aimed to give a basic engine model for the VTEC vehicle simulations. Compressor and turbine maps are based upon existing maps and/or qualified, realistic estimations. Themore » reference engine is a MD 13 US07 475 Hp. Phase I was completed in May 2006 which determined that an increase in fuel efficiency for the engine of 10.5% over the OICA cycle, and 8.2% over a road cycle was possible. The net increase in fuel efficiency would be 5% when coupled to a CVT and operated over simulated highway conditions. In Phase II an economic analysis was performed on the engine with turbocompound (TC) and a Continuously Variable Transmission (CVT). The system was analyzed to determine the payback time needed for the added cost of the TC and CVT system. The analysis was performed by considering two different production scenarios of 10,000 and 60,000 units annually. The cost estimate includes the turbocharger, the turbocompound unit, the interstage duct diffuser and installation details, the modifications necessary on the engine and the CVT. Even with the cheapest fuel and the lowest improvement, the pay back time is only slightly more than 12 months. A gear train is necessary between the engine crankshaft and turbocompound unit. This is considered to be relatively straight forward with no design problems.« less

Preliminary Axial Flow Turbine Design and Off-Design Performance Analysis Methods for Rotary Wing Aircraft Engines. Part 2; Applications

NASA Technical Reports Server (NTRS)

Chen, Shu-cheng, S.

2009-01-01

In this paper, preliminary studies on two turbine engine applications relevant to the tilt-rotor rotary wing aircraft are performed. The first case-study is the application of variable pitch turbine for the turbine performance improvement when operating at a substantially lower shaft speed. The calculations are made on the 75 percent speed and the 50 percent speed of operations. Our results indicate that with the use of the variable pitch turbines, a nominal (3 percent (probable) to 5 percent (hypothetical)) efficiency improvement at the 75 percent speed, and a notable (6 percent (probable) to 12 percent (hypothetical)) efficiency improvement at the 50 percent speed, without sacrificing the turbine power productions, are achievable if the technical difficulty of turning the turbine vanes and blades can be circumvented. The second casestudy is the contingency turbine power generation for the tilt-rotor aircraft in the One Engine Inoperative (OEI) scenario. For this study, calculations are performed on two promising methods: throttle push and steam injection. By isolating the power turbine and limiting its air mass flow rate to be no more than the air flow intake of the take-off operation, while increasing the turbine inlet total temperature (simulating the throttle push) or increasing the air-steam mixture flow rate (simulating the steam injection condition), our results show that an amount of 30 to 45 percent extra power, to the nominal take-off power, can be generated by either of the two methods. The methods of approach, the results, and discussions of these studies are presented in this paper.

40 CFR 1042.140 - Maximum engine power, displacement, power density, and maximum in-use engine speed.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 34 2012-07-01 2012-07-01 false Maximum engine power, displacement... Maximum engine power, displacement, power density, and maximum in-use engine speed. This section describes how to determine the maximum engine power, displacement, and power density of an engine for the...

40 CFR 1042.140 - Maximum engine power, displacement, power density, and maximum in-use engine speed.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 34 2013-07-01 2013-07-01 false Maximum engine power, displacement... Maximum engine power, displacement, power density, and maximum in-use engine speed. This section describes how to determine the maximum engine power, displacement, and power density of an engine for the...

System and method of vehicle operating condition management

DOEpatents

Sujan, Vivek A.; Vajapeyazula, Phani; Follen, Kenneth; Wu, An; Moffett, Barty L.

2015-10-20

A vehicle operating condition profile can be determined over a given route while also considering imposed constraints such as deviation from time targets, deviation from maximum governed speed limits, etc. Given current vehicle speed, engine state and transmission state, the present disclosure optimally manages the engine map and transmission to provide a recommended vehicle operating condition that optimizes fuel consumption in transitioning from one vehicle state to a target state. Exemplary embodiments provide for offline and online optimizations relative to fuel consumption. The benefit is increased freight efficiency in transporting cargo from source to destination by minimizing fuel consumption and maintaining drivability.

40 CFR 86.1380-2004 - Load response test.

Code of Federal Regulations, 2013 CFR

2013-07-01

...) The test has 5 separate measurement segments, each identified by a specific engine speed. At each of the following speeds, beginning with the lowest torque point at that engine speed within the NTE.... Prior to the beginning of each measurement segment, the engine shall be warmed up at the supplemental...

40 CFR 86.1380-2004 - Load response test.

Code of Federal Regulations, 2011 CFR

2011-07-01

...) The test has 5 separate measurement segments, each identified by a specific engine speed. At each of the following speeds, beginning with the lowest torque point at that engine speed within the NTE.... Prior to the beginning of each measurement segment, the engine shall be warmed up at the supplemental...

40 CFR 86.1380-2004 - Load response test.

Code of Federal Regulations, 2012 CFR

2012-07-01

...) The test has 5 separate measurement segments, each identified by a specific engine speed. At each of the following speeds, beginning with the lowest torque point at that engine speed within the NTE.... Prior to the beginning of each measurement segment, the engine shall be warmed up at the supplemental...

40 CFR 86.1380-2004 - Load response test.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) The test has 5 separate measurement segments, each identified by a specific engine speed. At each of the following speeds, beginning with the lowest torque point at that engine speed within the NTE.... Prior to the beginning of each measurement segment, the engine shall be warmed up at the supplemental...

40 CFR Appendix B to Subpart E of... - Tables

Code of Federal Regulations, 2010 CFR

2010-07-01

... Variable-Speed Engines Test segment Mode number Engine speed 1 Observed torque 2 (percent of max. observed...'s specifications. Idle speed is specified by the manufacturer. 2 Torque (non-idle): Throttle fully open for 100 percent points. Other non-idle points: ± 2 percent of engine maximum value. Torque (idle...

14 CFR 33.84 - Engine overtorque test.

Code of Federal Regulations, 2011 CFR

2011-01-01

... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.84 Engine overtorque test. (a) If approval of a maximum engine overtorque is sought for an engine incorporating a free power turbine... at least 21/2 minutes duration. (2) A power turbine rotational speed equal to the highest speed at...

14 CFR 33.84 - Engine overtorque test.

Code of Federal Regulations, 2014 CFR

2014-01-01

... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.84 Engine overtorque test. (a) If approval of a maximum engine overtorque is sought for an engine incorporating a free power turbine... at least 21/2 minutes duration. (2) A power turbine rotational speed equal to the highest speed at...

14 CFR 33.84 - Engine overtorque test.

Code of Federal Regulations, 2013 CFR

2013-01-01

... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.84 Engine overtorque test. (a) If approval of a maximum engine overtorque is sought for an engine incorporating a free power turbine... at least 21/2 minutes duration. (2) A power turbine rotational speed equal to the highest speed at...

Study of occupational stress among railway engine pilots

PubMed Central

Kumar, Devesh; Singh, Jai Vir; Kharwar, Poonam S.

2011-01-01

Background: Traffic volume and speed is going to be increased in Indian Railways successively, leading to higher stress in staff connected with train operations. The jobs of railway engine pilots come under the category of high-strain jobs, necessitating a need to conduct multicentric study to unfold the factors associated with occupational stress and organizational strategies. Materials and Methods: Present study covered 185 railway engine pilots and office clerks working in various railway zones by incidental method. Occupational Stress Index (OSI) test developed by Srivastva and Singh, questionnaire of specific stressors constructed by authors and laboratory test battery for psychological screening of high-speed train pilots were used as tools. Results: Means of OSI and all the 12 occupational stressors of railway engine pilots were found significantly higher to that of office clerks. Means of OSI and occupational stressors of goods train pilots were significantly higher in comparison to high-speed train pilots and passenger train pilots. Study revealed positive correlation of speed perception and complex reaction time tests and negative correlation of other constituent tests of laboratory test battery to OSI test. Highest subgroup of stressor observedwas role overload followed by role conflict. Conclusions: These findings provide a prima facie evidence of higher occupational stress among railway engine pilots because of identified specific stressors prevalent in their job and explore the possible intervention strategies for its reduction. Significant correlation is noticed between OSI and laboratory test results, indicating its relevant utility in preliminary psychological screening. PMID:21808497

Gas turbine engine fuel control

NASA Technical Reports Server (NTRS)

Gold, H. S. (Inventor)

1973-01-01

A variable orifice system is described that is responsive to compressor inlet pressure and temperature, compressor discharge pressure and rotational speed of a gas-turbine engine. It is incorporated into a hydraulic circuit that includes a zero gradient pump driven at a speed proportional to the speed of the engine. The resulting system provides control of fuel rate for starting, steady running, acceleration and deceleration under varying altitudes and flight speeds.

The effect of chine tires on nose gear water-spray characteristics of a twin engine airplane

NASA Technical Reports Server (NTRS)

Yager, T. J.; Stubbs, S. M.; Mccarty, J. L.

1975-01-01

An experimental investigation was performed to evaluate the effectiveness of nose gear chine tires in eliminating or minimizing the engine spray ingestion problem encountered on several occasions by the Merlin 4, a twin-engine propjet airplane. A study of the photographic and television coverage indicated that under similar test conditions the spray from the chine tires presented less of a potential engine spray ingestion problem than the conventional tires. Neither tire configuration appeared to pose any ingestion problem at aircraft speeds in excess of the hydroplaning speed for each tire, however, significant differences were noted in the spray patterns of the two sets of tires at sub-hydroplaning speeds. At sub-hydroplaning speeds, the conventional tires produced substantial spray above the wing which approached the general area of the engine air inlet at lower test speeds. The chine tires produced two distinct spray plumes at sub-hydroplaning speeds: one low-level plume which presented no apparent threat of ingestion, and one which at most test speeds was observed to be below the wing leading edge and thus displaced from the intakes on the engine nacelle.

Application of the ABC helicopter to the emergency medical service role

NASA Technical Reports Server (NTRS)

Levine, L. S.

1981-01-01

Attention is called to the use of helicopters in transporting the sick and injured to medical facilities. It is noted that the helicopter's speed of response and delivery increases patient survival rates and may reduce the cost of medical care and its burden on society. Among the vehicle characteristics desired for this use are a cruising speed of 200 knots, a single engine hover capability at 10,000 ft, and an absence of a tail rotor. Three designs for helicopters incorporating such new technologies as digital/optical control systems, all composite air-frames, and third-generation airfoils are presented. A sensitivity analysis is conducted to show the effect of design speed, mission radius, and single engine hover capability on vehicle weight, fuel consumption, operating costs, and productivity.

Effects of turbine cooling assumptions on performance and sizing of high-speed civil transport

NASA Technical Reports Server (NTRS)

Senick, Paul F.

1992-01-01

The analytical study presented examines the effects of varying turbine cooling assumptions on the performance of a high speed civil transport propulsion system as well as the sizing sensitivity of this aircraft to these performance variations. The propulsion concept employed in this study was a two spool, variable cycle engine with a sea level thrust of 55,000 lbf. The aircraft used for this study was a 250 passenger vehicle with a cruise Mach number of 2.4 and 5000 nautical mile range. The differences in turbine cooling assumptions were represented by varying the amount of high pressure compressor bleed air used to cool the turbines. It was found that as this cooling amount increased, engine size and weight increased, but specific fuel consumption (SFC) decreased at takeoff and climb only. Because most time is spent at cruise, the SFC advantage of the higher bleed engines seen during subsonic flight was minimized and the lower bleed, lighter engines led to the lowest takeoff gross weight vehicles. Finally, the change in aircraft takeoff gross weight versus turbine cooling level is presented.

A Theoretical and Experimental Investigation of the Lift and Drag Characteristics of Hydrofoils at Subcritical and Supercritical Speeds

NASA Technical Reports Server (NTRS)

Wadlin, Kenneth L; Shuford, Charles L , Jr; Mcgehee, John R

1955-01-01

A theoretical and experimental investigation at subcavitation speeds was made of the effect of the free-water surface and rigid boundaries on the lift and drag of an aspect-ratio-10 hydrofoil at both subcritical and supercritical speeds and of an aspect ratio-4 hydrofoil at supercritical speeds. Approximate theoretical solutions for the effects of the free-water surface and rigid boundaries on drag at subcritical speeds are developed. An approximate theoretical solution for the effects of these boundaries on drag at subcritical speeds is also presented. The agreement between theory and experiment at both supercritical and subcritical speeds is satisfactory for engineering calculations of hydrofoil characteristics from aerodynamic data. The experimental investigation indicated no appreciable effect of the limiting speed of wave propagation on lift-curve slope or angle of zero lift. It also showed that the increase in drag as the critical speed is approached from the supercritical range is gradual. The result is contrary to the abrupt increase at the critical speed predicted by theory.

Experimental evaluation of oxygen-enriched air and emulsified fuels in a six-cylinder diesel engine

NASA Astrophysics Data System (ADS)

Sekar, R. R.; Marr, W. W.; Cole, R. L.; Marciniak, T. J.; Longman, D. E.

1993-01-01

The objectives of this investigation are to (1) determine the technical feasibility of using oxygen-enriched air to increase the efficiency of and reduce emissions from diesel engines, (2) examine the effects of water-emulsified fuel on the formation of nitrogen oxides in oxygen-enriched combustion, and (3) investigate the use of lower-grade fuels in high-speed diesel engines by emulsifying the fuel with water. These tests, completed on a Caterpillar model 3406B, six-cylinder engine are a scale-up from previous, single-cylinder-engine tests. The engine was tested with (1) intake-air oxygen levels up to 30%, (2) water content up to 20% of the fuel, (3) three fuel-injection timings, and (4) three fuel-flow rates (power levels). The Taguchi technique for experimental design was used to minimize the number of experimental points in the test matrix. Four separate test matrices were run to cover two different fuel-flow-rate strategies and two different fuels (No. 2 diesel and No. 6 diesel). A liquid-oxygen tank located outside the test cell supplied the oxygen for the tests. The only modification of the engine was installation of a pressure transducer in one cylinder. All tests were run at 1800 rpm, which corresponds to the synchronous speed of a 60-Hz generator. Test results show that oxygen enrichment results in power increases of 50% or more while significantly decreasing the levels of smoke and particulates emitted. The increase in power was accompanied by a small increase in thermal efficiency. Maximum engine power was limited by the test-cell dynamometer capacity and the capacity of the fuel-injection pump. Oxygen enrichment increases nitrogen-oxide emissions significantly. No adverse effects of oxygen enrichment on the turbocharger were observed. The engine operated successfully with No. 6 fuel, but it operated at a lower thermal efficiency and emitted more smoke and particulates than with No. 2 fuel.

Engine speed control apparatus

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

Ishii, M.; Miyazaki, M.; Nakamura, N.

1986-11-04

This patent describes an engine speed control apparatus. The system comprises an actuator for adjusting an engine speed, a first unit for computing a desired engine speed, a second unit for detecting the actual engine speed, and a third unit for detecting the difference between the outputs of the first and second units. The system also includes a fourth unit for computing a control pulse width for the actuator in accordance with the output of the third unit, a fifth unit for generating a control signal, a sixth unit for driving the actuator in response to the output of themore » fifth unit, and a seventh unit for computing an optimal halt time to interrupt the driving of the actuator. The actuator is driven intermittently in conformity in the control pulse width and the halt time.« less

Thermodynamic Cycle Analysis of Magnetohydrodynamic-Bypass Airbreathing Hypersonic Engines

NASA Technical Reports Server (NTRS)

Litchford, Ron J.; Bityurin, Valentine A.; Lineberry, John T.

1999-01-01

Established analyses of conventional ramjet/scramjet performance characteristics indicate that a considerable decrease in efficiency can be expected at off-design flight conditions. This can be explained, in large part, by the deterioration of intake mass flow and limited inlet compression at low flight speeds and by the onset of thrust degradation effects associated with increased burner entry temperature at high flight speeds. In combination, these effects tend to impose lower and upper Mach number limits for practical flight. It has been noted, however, that Magnetohydrodynamic (MHD) energy management techniques represent a possible means for extending the flight Mach number envelope of conventional engines. By transferring enthalpy between different stages of the engine cycle, it appears that the onset of thrust degradation may be delayed to higher flight speeds. Obviously, the introduction of additional process inefficiencies is inevitable with this approach, but it is believed that these losses are more than compensated through optimization of the combustion process. The fundamental idea is to use MHD energy conversion processes to extract and bypass a portion of the intake kinetic energy around the burner. We refer to this general class of propulsion system as an MHD-bypass engine. In this paper, we quantitatively assess the performance potential and scientific feasibility of MHD-bypass airbreathing hypersonic engines using ideal gasdynamics and fundamental thermodynamic principles.

[Experimental study on particle size distributions of an engine fueled with blends of biodiesel].

PubMed

Lu, Xiao-Ming; Ge, Yun-Shan; Han, Xiu-Kun; Wu, Si-Jin; Zhu, Rong-Fu; He, Chao

2007-04-01

The purpose of this study is to obtain the particle size distributions of an engine fueled biodiesel and its blends. A turbocharged DI diesel engine was tested on a dynamometer. A pump of 80 L/min and fiber glass filters with diameter of 90 mm were used to sample engine particles in exhaust pipe. Sampling duration was 10 minutes. Particle size distributions were measured by a laser diffraction particle size analyzer. Results indicated that higher engine speed resulted in smaller particle sizes and narrower distributions. The modes on distribution curves and mode variation were larger with dry samples than with wet samples (dry: around 10 - 12 microm vs. wet: around 4 - 10 microm). At low speed, Sauter mean diameter d32 of dry samples was the biggest with B100, the smallest with diesel fuel, and among them with B20, while at high speed, d32 the biggest with B20, the smallest with B100, and in middle with diesel. Median diameter d(0.5) also reflected the results. Except for 2 000 r/min, d32 of wet with B20 is the biggest, the smallest with diesel, and in middle with B100. The large mode variation resulted in increase of d32.

Unsteady pressure loads in a generic high speed engine model

NASA Technical Reports Server (NTRS)

Parrott, Tony L.; Jones, Michael G.; Thurlow, Ernie M.

1992-01-01

Unsteady pressure loads were measured along the top interior wall of a generic high-speed engine (GHSE) model undergoing performance tests in the combustion-Heated Scramjet Test Facility at the Langley Research Center. Flow to the model inlet was simulated at 72000 ft and a flight Mach number of 4. The inlet Mach number was 3.5 with a total temperature and pressure of 1640 R and 92 psia. The unsteady pressure loads were measured with 5 piezoresistive gages, recessed into the wall 4 to 12 gage diameters to reduce incident heat flux to the diaphragms, and distributed from the inlet to the combustor. Contributors to the unsteady pressure loads included boundary layer turbulence, combustion noise, and transients generated by unstart loads. Typical turbulent boundary layer rms pressures in the inlet ranged from 133 dB in the inlet to 181 dB in the combustor over the frequency range from 0 to 5 kHz. Downstream of the inlet exist, combustion noise was shown to dominate boundary layer turbulence noise at increased heat release rates. Noise levels in the isolator section increased by 15 dB when the fuel-air ratio was increased from 0.37 to 0.57 of the stoichiometric ratio. Transient pressure disturbances associated with engine unstarts were measured in the inlet and have an upstream propagation speed of about 7 ft/sec and pressure jumps of at least 3 psia.

Design and analysis of a fuel-efficient single-engine, turboprop-powered, business airplane

NASA Technical Reports Server (NTRS)

Martin, G. L.; Everest, D. E., Jr.; Lovell, W. A.; Price, J. E.; Walkley, K. B.; Washburn, G. F.

1981-01-01

The speed, range, payload, and fuel efficiency of a general aviation airplane powered by one turboprop engine was determined and compared to a twin engine turboprop aircraft. An airplane configuration was developed which can carry six people for a noreserve range of 2,408 km at a cruise speed above 154 m/s, and a cruise altitude of about 9,144 m. The cruise speed is comparable to that of the fastest of the current twin turboprop powered airplanes. It is found that the airplane has a cruise specific range greater than all twin turboprop engine airplanes flying in its speed range and most twin piston engine airplanes flying at considerably slower cruise airspeeds.

Role of structural noise in aircraft pressure cockpit from vibration action of new-generation engines

NASA Astrophysics Data System (ADS)

Baklanov, V. S.

2016-07-01

The evolution of new-generation aircraft engines is transitioning from a bypass ratio of 4-6 to an increased ratio of 8-12. This is leading to substantial broadening of the vibration spectrum of engines with a shift to the low-frequency range due to decreased rotation speed of the fan rotor, in turn requiring new solutions to decrease structural noise from engine vibrations to ensure comfort in the cockpits and cabins of aircraft.

Turbulent flame propagation and combustion in spark ignition engines

NASA Technical Reports Server (NTRS)

Beretta, G. P.; Rashidi, M.; Keck, J. C.

1983-01-01

Pressure measurements synchronized with high-speed motion-picture records of flame propagation have been made in a transparent-piston engine. The data show that the initial expansion speed of the flame front is close to that of a laminar flame. As the flame expands, its speed rapidly accelerates to a quasi-steady value comparable with that of the turbulent velocity fluctuations in the unburned gas. During the quasi-steady propagation phase, a significant fraction of the gas behind the visible front is unburned. Final burnout of the charge may be approximated by an exponential decay in time. The data have been analyzed in a model-independent way to obtain a set of empirical equations for calculating mass burning rates in spark-ignition engines. The burning equations contain three parameters: the laminar burning speed, a characteristic speed (uT), and a characteristic length (lT). The laminar burning speed is known from laboratory measurements. Tentative correlations relating uT and lT to engine geometry and operating variables have been derived from the engine data.

The application of LQR synthesis techniques to the turboshaft engine control problem. [Linear Quadratic Regulator

NASA Technical Reports Server (NTRS)

Pfeil, W. H.; De Los Reyes, G.; Bobula, G. A.

1985-01-01

A power turbine governor was designed for a recent-technology turboshaft engine coupled to a modern, articulated rotor system using Linear Quadratic Regulator (LQR) and Kalman Filter (KF) techniques. A linear, state-space model of the engine and rotor system was derived for six engine power settings from flight idle to maximum continuous. An integrator was appended to the fuel flow input to reduce the steady-state governor error to zero. Feedback gains were calculated for the system states at each power setting using the LQR technique. The main rotor tip speed state is not measurable, so a Kalman Filter of the rotor was used to estimate this state. The crossover of the system was increased to 10 rad/s compared to 2 rad/sec for a current governor. Initial computer simulations with a nonlinear engine model indicate a significant decrease in power turbine speed variation with the LQR governor compared to a conventional governor.

Determination of combustion parameters using engine crankshaft speed

NASA Astrophysics Data System (ADS)

Taglialatela, F.; Lavorgna, M.; Mancaruso, E.; Vaglieco, B. M.

2013-07-01

Electronic engine controls based on real time diagnosis of combustion process can significantly help in complying with the stricter and stricter regulations on pollutants emissions and fuel consumption. The most important parameter for the evaluation of combustion quality in internal combustion engines is the in-cylinder pressure, but its direct measurement is very expensive and involves an intrusive approach to the cylinder. Previous researches demonstrated the direct relationship existing between in-cylinder pressure and engine crankshaft speed and several authors tried to reconstruct the pressure cycle on the basis of the engine speed signal. In this paper we propose the use of a Multi-Layer Perceptron neural network to model the relationship between the engine crankshaft speed and some parameters derived from the in-cylinder pressure cycle. This allows to have a non-intrusive estimation of cylinder pressure and a real time evaluation of combustion quality. The structure of the model and the training procedure is outlined in the paper. A possible combustion controller using the information extracted from the crankshaft speed information is also proposed. The application of the neural network model is demonstrated on a single-cylinder spark ignition engine tested in a wide range of speeds and loads. Results confirm that a good estimation of some combustion pressure parameters can be obtained by means of a suitable processing of crankshaft speed signal.

The Effect of Faster Engine Response on the Lateral Directional Control of a Damaged Aircraft

NASA Technical Reports Server (NTRS)

May, Ryan D.; Lemon, Kimberly A.; Csank, Jeffrey T.; Litt, Jonathan S.; Guo, Ten-Huei

2012-01-01

The integration of flight control and propulsion control has been a much discussed topic, especially for emergencies where the engines may be able to help stabilize and safely land a damaged aircraft. Previous research has shown that for the engines to be effective as flight control actuators, the response time to throttle commands must be improved. Other work has developed control modes that accept a higher risk of engine failure in exchange for improved engine response during an emergency. In this effort, a nonlinear engine model (the Commercial Modular Aero-Propulsion System Simulation 40k) has been integrated with a nonlinear airframe model (the Generic Transport Model) in order to evaluate the use of enhanced-response engines as alternative yaw rate control effectors. Tests of disturbance rejection and command tracking were used to determine the impact of the engines on the aircraft's dynamical behavior. Three engine control enhancements that improve the response time of the engine were implemented and tested in the integrated simulation. The enhancements were shown to increase the engine s effectiveness as a yaw rate control effector when used in an automatic feedback loop. The improvement is highly dependent upon flight condition; the airframe behavior is markedly improved at low altitude, low speed conditions, and relatively unchanged at high altitude, high speed.

The results of low-speed wind tunnel tests to investigate the effects of the NASA refan JT8D engine nacelles on the stability and control characteristics of the Boeing 727-200

NASA Technical Reports Server (NTRS)

Shirkey, M. D.

1973-01-01

The results from two low-speed wind tunnel tests of the Boeing 727-200 airplane as configured with the NASA refan JT8D-109 turbofan engines are presented. The objective of these tests was to determine the effects of the refan installation on the low-speed stability and control characteristics of the 727 airplane. Four side nacelle locations were tested to insure that aerodynamic interactions of the nacelles and empennage would be optimized. The optimum location was judged to be the same as that of the production JT8D-9 engines; the current production engine mounts can be used for this location. Some small changes in the basic airplane characteristics are attributable to the refan nacelles. The flaps up longitudinal and lateral-directional stability are both slightly increased for low angles of attack and sideslip respectively. The longitudinal stability at stall is improved for both the flaps up and landing flap configurations. The high attitude characteristics of the basic airplane are not significantly altered by the refan nacelle installation. Directional control capability is not affected by the refan nacelles.

Investigation of dynamic characteristics of a turbine-propeller engine

NASA Technical Reports Server (NTRS)

Oppenheimer, Frank L; Jacques, James R

1951-01-01

Time constants that characterize engine speed response of a turbine-propeller engine over the cruising speed range for various values of constant fuel flow and constant blade angle were obtained both from steady-state characteristics and from transient operation. Magnitude of speed response to changes in fuel flow and blade angle was investigated and is presented in the form of gain factors. Results indicate that at any given value of speed in the engine cruising speed range, time constants obtained both from steady-state characteristics and from transient operation agree satisfactorily for any given constant fuel flow, whereas time constants obtained from transient operation exceed time constants obtained from steady-state characteristics by approximately 14 percent for any given blade angle.

Concept Development of a Mach 1.6 High-Speed Civil Transport

NASA Technical Reports Server (NTRS)

Shields, Elwood W.; Fenbert, James W.; Ozoroski, Lori P.; Geiselhart, Karl A.

1999-01-01

A high-speed civil transport configuration with a Mach number of 1.6 was developed as part of the NASA High-Speed Research Program to serve as a baseline for assessing advanced technologies required for an aircraft with a service entry date of 2005. This configuration offered more favorable solutions to environmental concerns than configurations with higher Mach numbers. The Mach 1.6 configuration was designed for a 6500 n.mi. mission with a 250-passenger payload. The baseline configuration has a wing area of 8732 square feet a takeoff gross weight of 591570 lb, and four 41000-lb advanced turbine bypass engines defined by NASA. These engines have axisymmetric mixer-ejector nozzles that are assumed to yield 20 dB of noise suppression during takeoff, which is assumed to satisfy, the FAR Stage III noise requirements. Any substantial reduction in this assumed level of suppression would require oversizing the engines to meet community noise regulations and would severly impact the gross weight of the aircraft at takeoff. These engines yield a ratio of takeoff thrust to weight of 0.277 and a takeoff wing loading of 67.8 lb/square feet that results in a rotation speed of 169 knots. The approach velocity of the sized configuration at the end of the mission is 131 knots. The baseline configuration was resized with an engine having a projected life of 9000 hr for hot rotating parts and 18000 hr for the rest of the engine, as required for commercial use on an aircraft with a service entry date of 2005. Results show an increase in vehicle takeoff gross weight of approximately 58700 lb. This report presents the details of the configuration development, mass properties, aerodynamic design, propulsion system and integration, mission performance, and sizing.

A study experiment of auto idle application in the excavator engine performance

NASA Astrophysics Data System (ADS)

Purwanto, Wawan; Maksum, Hasan; Putra, Dwi Sudarno; Azmi, Meri; Wahyudi, Retno

2016-03-01

The purpose of this study was to analyze the effect of applying auto idle to excavator engine performance, such as machine unitization and fuel consumption in Excavator. Steps to be done are to modify the system JA 44 and 67 in Vehicle Electronic Control Unit (V-ECU). The modifications will be obtained from the pattern of the engine speed. If the excavator attachment is not operated, the engine speed will return to the idle speed automatically. From the experiment results the auto idle reduces fuel consumption in excavator engine.

A study experiment of auto idle application in the excavator engine performance

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

Purwanto, Wawan, E-mail: wawan5527@gmail.com; Maksum, Hasan; Putra, Dwi Sudarno, E-mail: dwisudarnoputra@ft.unp.ac.id

2016-03-29

The purpose of this study was to analyze the effect of applying auto idle to excavator engine performance, such as machine unitization and fuel consumption in Excavator. Steps to be done are to modify the system JA 44 and 67 in Vehicle Electronic Control Unit (V-ECU). The modifications will be obtained from the pattern of the engine speed. If the excavator attachment is not operated, the engine speed will return to the idle speed automatically. From the experiment results the auto idle reduces fuel consumption in excavator engine.

Optimal trajectories for an aerospace plane. Part 1: Formulation, results, and analysis

NASA Technical Reports Server (NTRS)

Miele, Angelo; Lee, W. Y.; Wu, G. D.

1990-01-01

The optimization of the trajectories of an aerospace plane is discussed. This is a hypervelocity vehicle capable of achieving orbital speed, while taking off horizontally. The vehicle is propelled by four types of engines: turbojet engines for flight at subsonic speeds/low supersonic speeds; ramjet engines for flight at moderate supersonic speeds/low hypersonic speeds; scramjet engines for flight at hypersonic speeds; and rocket engines for flight at near-orbital speeds. A single-stage-to-orbit (SSTO) configuration is considered, and the transition from low supersonic speeds to orbital speeds is studied under the following assumptions: the turbojet portion of the trajectory has been completed; the aerospace plane is controlled via the angle of attack and the power setting; the aerodynamic model is the generic hypersonic aerodynamics model example (GHAME). Concerning the engine model, three options are considered: (EM1), a ramjet/scramjet combination in which the scramjet specific impulse tends to a nearly-constant value at large Mach numbers; (EM2), a ramjet/scramjet combination in which the scramjet specific impulse decreases monotonically at large Mach numbers; and (EM3), a ramjet/scramjet/rocket combination in which, owing to stagnation temperature limitations, the scramjet operates only at M approx. less than 15; at higher Mach numbers, the scramjet is shut off and the aerospace plane is driven only by the rocket engines. Under the above assumptions, four optimization problems are solved using the sequential gradient-restoration algorithm for optimal control problems: (P1) minimization of the weight of fuel consumed; (P2) minimization of the peak dynamic pressure; (P3) minimization of the peak heating rate; and (P4) minimization of the peak tangential acceleration.

Energy efficient engine: High pressure turbine uncooled rig technology report

NASA Technical Reports Server (NTRS)

Gardner, W. B.

1979-01-01

Results obtained from testing five performance builds (three vane cascades and two rotating rigs of the Energy Efficient Engine uncooled rig have established the uncooled aerodynamic efficiency of the high-pressure turbine at 91.1 percent. This efficiency level was attained by increasing the rim speed and annulus area (AN(2)), and by increasing the turbine reaction level. The increase in AN(2) resulted in a performance improvement of 1.15 percent. At the design point pressure ratio, the increased reaction level rig demonstrated an efficiency of 91.1 percent. The results of this program have verified the aerodynamic design assumptions established for the Energy Efficient Engine high-pressure turbine component.

Italian High-speed Airplane Engines

NASA Technical Reports Server (NTRS)

Bona, C F

1940-01-01

This paper presents an account of Italian high-speed engine designs. The tests were performed on the Fiat AS6 engine, and all components of that engine are discussed from cylinders to superchargers as well as the test set-up. The results of the bench tests are given along with the performance of the engines in various races.

40 CFR 1065.510 - Engine mapping.

Code of Federal Regulations, 2011 CFR

2011-07-01

... the warm-up until the engine coolant, block, or head absolute temperature is within ± 2% of its mean... demand to minimum, use the dynamometer or other loading device to target a torque of zero on the engine's...-speed governor, operate the engine at warm idle speed and zero torque on the engine's primary output...

Choice of Tuning Parameters on 3D IC Engine Simulations Using G-Equation

DOE PAGES

Liu, Jinlong; Szybist, James; Dumitrescu, Cosmin

2018-04-03

3D CFD spark-ignition IC engine simulations are extremely complex for the regular user. Truly-predictive CFD simulations for the turbulent flame combustion that solve fully coupled transport/chemistry equations may require large computational capabilities unavailable to regular CFD users. A solution is to use a simpler phenomenological model such as the G-equation that decouples transport/chemistry result. Such simulation can still provide acceptable and faster results at the expense of predictive capabilities. While the G-equation is well understood within the experienced modeling community, the goal of this paper is to document some of them for a novice or less experienced CFD user whomore » may not be aware that phenomenological models of turbulent flame combustion usually require heavy tuning and calibration from the user to mimic experimental observations. This study used ANSYS® Forte, Version 17.2, and the built-in G-equation model, to investigate two tuning constants that influence flame propagation in 3D CFD SI engine simulations: the stretch factor coefficient, Cms and the flame development coefficient, Cm2. After identifying several Cm2-Cms pairs that matched experimental data at one operating conditions, simulation results showed that engine models that used different Cm2-Cms sets predicted similar combustion performance, when the spark timing, engine load, and engine speed were changed from the operating condition used to validate the CFD simulation. A dramatic shift was observed when engine speed was doubled, which suggested that the flame stretch coefficient, Cms, had a much larger influence at higher engine speeds compared to the flame development coefficient, Cm2. Therefore, the Cm2-Cms sets that predicted a higher turbulent flame under higher in-cylinder pressure and temperature increased the peak pressure and efficiency. This suggest that the choice of the Cm2-Cms will affect the G-equation-based simulation accuracy when engine speed increases from the one used to validate the model. As a result, for the less-experienced CFD user and in the absence of enough experimental data that would help retune the tuning parameters at various operating conditions, the purpose of a good G-equation-based 3D engine simulation is to guide and/or complement experimental investigations, not the other way around. Only a truly-predictive simulation that fully couples the turbulence/chemistry equations can help reduce the amount of experimental work.« less

Choice of Tuning Parameters on 3D IC Engine Simulations Using G-Equation

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

Liu, Jinlong; Szybist, James; Dumitrescu, Cosmin

3D CFD spark-ignition IC engine simulations are extremely complex for the regular user. Truly-predictive CFD simulations for the turbulent flame combustion that solve fully coupled transport/chemistry equations may require large computational capabilities unavailable to regular CFD users. A solution is to use a simpler phenomenological model such as the G-equation that decouples transport/chemistry result. Such simulation can still provide acceptable and faster results at the expense of predictive capabilities. While the G-equation is well understood within the experienced modeling community, the goal of this paper is to document some of them for a novice or less experienced CFD user whomore » may not be aware that phenomenological models of turbulent flame combustion usually require heavy tuning and calibration from the user to mimic experimental observations. This study used ANSYS® Forte, Version 17.2, and the built-in G-equation model, to investigate two tuning constants that influence flame propagation in 3D CFD SI engine simulations: the stretch factor coefficient, Cms and the flame development coefficient, Cm2. After identifying several Cm2-Cms pairs that matched experimental data at one operating conditions, simulation results showed that engine models that used different Cm2-Cms sets predicted similar combustion performance, when the spark timing, engine load, and engine speed were changed from the operating condition used to validate the CFD simulation. A dramatic shift was observed when engine speed was doubled, which suggested that the flame stretch coefficient, Cms, had a much larger influence at higher engine speeds compared to the flame development coefficient, Cm2. Therefore, the Cm2-Cms sets that predicted a higher turbulent flame under higher in-cylinder pressure and temperature increased the peak pressure and efficiency. This suggest that the choice of the Cm2-Cms will affect the G-equation-based simulation accuracy when engine speed increases from the one used to validate the model. As a result, for the less-experienced CFD user and in the absence of enough experimental data that would help retune the tuning parameters at various operating conditions, the purpose of a good G-equation-based 3D engine simulation is to guide and/or complement experimental investigations, not the other way around. Only a truly-predictive simulation that fully couples the turbulence/chemistry equations can help reduce the amount of experimental work.« less

Experimental quiet engine program

NASA Technical Reports Server (NTRS)

Cornell, W. G.

1975-01-01

Full-scale low-tip-speed fans, a full-scale high-tip-speed fan, scale model versions of fans, and two full-scale high-bypass-ratio turbofan engines, were designed, fabricated, tested, and evaluated. Turbine noise suppression was investigated. Preliminary design studies of flight propulsion system concepts were used in application studies to determine acoustic-economic tradeoffs. Salient results are as follows: tradeoff evaluation of fan tip speed and blade loading; systematic data on source noise characteristics and suppression effectiveness; documentation of high- and low-fan-speed aerodynamic and acoustic technology; aerodynamic and acoustic evaluation of acoustic treatment configurations, casing tip bleed, serrated and variable pitch rotor blades, leaned outlet guide vanes, slotted tip casings, rotor blade shape modifications, and inlet noise suppression; systematic evaluation of aerodynamic and acoustic effects; flyover noise projections of engine test data; turbine noise suppression technology development; and tradeoff evaluation of preliminary design high-fan-speed and low-fan-speed flight engines.

Experimentally-determined external heat loss of automotive gas turbine engine

NASA Technical Reports Server (NTRS)

Meng, P. R.; Wulf, R. F.

1975-01-01

An external heat balance was conducted on a 150 HP two-shaft automotive gas turbine engine. The engine was enclosed in a calorimeter box and the temperature change of cooling air passing through the box was measured. Cooling airflow ranges of 1.6 to 2.1 lb-per-second and 0.8 to 1.1 lb-per-second were used. The engine housing heat loss increased as the cooling airflow through the calorimeter box was increased, as would be the case in a moving automobile. The heat balance between the total energy input and the sum of shaft power output and various losses compared within 30 percent at engine idle speeds and within 7 percent at full power.

Propulsive-lift concepts for improved low-speed performance of supersonic cruise arrow-wing configurations

NASA Technical Reports Server (NTRS)

Coe, P. L., Jr.

1976-01-01

Low-aspect-ratio highly swept arrow-wing supersonic aircraft possess high levels of aerodynamic efficiency at supersonic cruising speeds, however, their inherently poor low-speed lift characteristics require design constraints that compromise supersonic performance. The data discussed in this paper were obtained in wind tunnel tests with supersonic crusing configurations, in which propulsive-lift concepts were used to improve low-speed performance. The data show that the increased low-speed lift provided by propulsive-lift permits reduction of both wing size and installed thrust. This yields a batter engine/airframe match for improved supersonic cruise efficiency and range, while still providing acceptable take-off field lengths.

ARC-1962-A-29657-1

NASA Image and Video Library

1962-08-14

Ryan VZ-3RY over Ames in slow-speed flight. Smooth airflow over entire wing is indicated by tufts when wing had been modified to incorporate leading-edge slats. Tests showed that it could be flown at speeds as low as 6 knots when out of ground effect (which increases lift). April 1963 published in NASA SP-2002-4525 Memoirs of a Flight test Engineer (Seth Anderson)

Sample-based engine noise synthesis using an enhanced pitch-synchronous overlap-and-add method.

PubMed

Jagla, Jan; Maillard, Julien; Martin, Nadine

2012-11-01

An algorithm for the real time synthesis of internal combustion engine noise is presented. Through the analysis of a recorded engine noise signal of continuously varying engine speed, a dataset of sound samples is extracted allowing the real time synthesis of the noise induced by arbitrary evolutions of engine speed. The sound samples are extracted from a recording spanning the entire engine speed range. Each sample is delimitated such as to contain the sound emitted during one cycle of the engine plus the necessary overlap to ensure smooth transitions during the synthesis. The proposed approach, an extension of the PSOLA method introduced for speech processing, takes advantage of the specific periodicity of engine noise signals to locate the extraction instants of the sound samples. During the synthesis stage, the sound samples corresponding to the target engine speed evolution are concatenated with an overlap and add algorithm. It is shown that this method produces high quality audio restitution with a low computational load. It is therefore well suited for real time applications.

Analysis of an Increase in the Efficiency of a Spark Ignition Engine Through the Application of an Automotive Thermoelectric Generator

NASA Astrophysics Data System (ADS)

Merkisz, Jerzy; Fuc, Pawel; Lijewski, Piotr; Ziolkowski, Andrzej; Galant, Marta; Siedlecki, Maciej

2016-08-01

We have analyzed the increase of the overall efficiency of a spark ignition engine through energy recovery following the application of an automotive thermoelectric generator (ATEG) of our own design. The design of the generator was developed following emission investigations during vehicle driving under city traffic conditions. The measurement points were defined by actual operation conditions (engine speed and load), subsequently reproduced on an engine dynamometer. Both the vehicle used in the on-road tests and the engine dynamometer were fit with the same, downsized spark ignition engine (with high effective power-to-displacement ratio). The thermodynamic parameters of the exhaust gases (temperature and exhaust gas mass flow) were measured on the engine testbed, along with the fuel consumption and electric current generated by the thermoelectric modules. On this basis, the power of the ATEG and its impact on overall engine efficiency were determined.

14 CFR Appendix E to Part 135 - Helicopter Flight Recorder Specifications

Code of Federal Regulations, 2011 CFR

2011-01-01

... Keying On-Off (Discrete) 1 0.25 sec Power in Each Engine: Free Power Turbine Speed and Engine Torque 0-130% (power Turbine Speed) Full range (Torque) ±2% 1 speed 1 torque (per engine) 0.2% 1 to 0.4% 1 Main... Controls (Collective, Longitudinal Cyclic, Lateral Cyclic, Pedal) 3 Full range ±3% 2 0.5% 1 Flight Control...

14 CFR Appendix E to Part 135 - Helicopter Flight Recorder Specifications

Code of Federal Regulations, 2014 CFR

2014-01-01

... Keying On-Off (Discrete) 1 0.25 sec Power in Each Engine: Free Power Turbine Speed and Engine Torque 0-130% (power Turbine Speed) Full range (Torque) ±2% 1 speed 1 torque (per engine) 0.2% 1 to 0.4% 1 Main... Controls (Collective, Longitudinal Cyclic, Lateral Cyclic, Pedal) 3 Full range ±3% 2 0.5% 1 Flight Control...

14 CFR Appendix E to Part 135 - Helicopter Flight Recorder Specifications

Code of Federal Regulations, 2012 CFR

2012-01-01

... Keying On-Off (Discrete) 1 0.25 sec Power in Each Engine: Free Power Turbine Speed and Engine Torque 0-130% (power Turbine Speed) Full range (Torque) ±2% 1 speed 1 torque (per engine) 0.2% 1 to 0.4% 1 Main... Controls (Collective, Longitudinal Cyclic, Lateral Cyclic, Pedal) 3 Full range ±3% 2 0.5% 1 Flight Control...

Waste heat recovery on multiple low-speed reciprocating engines

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

Mayhew, R.E.

1982-09-01

With rising fuel costs, energy conservation has taken on added significance. Installation of Waste Heat Recovery Units (WHRU) on gas turbines is one method used in the past to reduce gas plant fuel consumption. More recently, waste heat recovery on multiple reciprocating compressor engines has also been identified as having energy conservation potential. This paper reviews the development and implementation of a Waste Heat Recovery Unit (WHRU) for multiple low speed engines at the Katy Gas Plant. WHRU's for these engines should be differentiated from high speed engines and gas turbines in that low speed engines produce low frequency, highmore » amplitude pulsating exhaust. The design of a waste heat system must take this potentially destructive pulsation into account. At Katy, the pulsation forces were measured at high amplitude frequencies and then used to design structural stiffness into the various components of the WHRU to minimize vibration and improve system reliability.« less

Waste heat recovery on multiple low-speed reciprocating engines

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

Mayhew, R.E.

1984-09-01

With rising fuel costs, energy conservation has taken on added significance. Installation of waste heat recovery units (WHRU's) on gas turbines is one method used in the past to reduce gas plant fuel consumption. More recently, waste heat recovery on multiple reciprocating compressor engines also has been identified as having energy conservation potential. This paper reviews the development and implementation of a WHRU for multiple low-speed engines at the Katy (TX) gas plant. WHRU's for these engines should be differentiated from high-speed engines and gas turbines in that low-speed engines produce low-frequency, high-amplitude pulsating exhaust. The design of a WHRUmore » system must take this potentially destructive pulsation into account. At Katy, the pulsation forces were measured at high-amplitude frequencies and then used to design a pulsation filter and structural stiffness into the various components of the WHRU to minimize vibration and improve system reliability.« less

Evaluation of Proteomic Search Engines for the Analysis of Histone Modifications

PubMed Central

2015-01-01

Identification of histone post-translational modifications (PTMs) is challenging for proteomics search engines. Including many histone PTMs in one search increases the number of candidate peptides dramatically, leading to low search speed and fewer identified spectra. To evaluate database search engines on identifying histone PTMs, we present a method in which one kind of modification is searched each time, for example, unmodified, individually modified, and multimodified, each search result is filtered with false discovery rate less than 1%, and the identifications of multiple search engines are combined to obtain confident results. We apply this method for eight search engines on histone data sets. We find that two search engines, pFind and Mascot, identify most of the confident results at a reasonable speed, so we recommend using them to identify histone modifications. During the evaluation, we also find some important aspects for the analysis of histone modifications. Our evaluation of different search engines on identifying histone modifications will hopefully help those who are hoping to enter the histone proteomics field. The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium with the data set identifier PXD001118. PMID:25167464

Evaluation of proteomic search engines for the analysis of histone modifications.

PubMed

Yuan, Zuo-Fei; Lin, Shu; Molden, Rosalynn C; Garcia, Benjamin A

2014-10-03

Identification of histone post-translational modifications (PTMs) is challenging for proteomics search engines. Including many histone PTMs in one search increases the number of candidate peptides dramatically, leading to low search speed and fewer identified spectra. To evaluate database search engines on identifying histone PTMs, we present a method in which one kind of modification is searched each time, for example, unmodified, individually modified, and multimodified, each search result is filtered with false discovery rate less than 1%, and the identifications of multiple search engines are combined to obtain confident results. We apply this method for eight search engines on histone data sets. We find that two search engines, pFind and Mascot, identify most of the confident results at a reasonable speed, so we recommend using them to identify histone modifications. During the evaluation, we also find some important aspects for the analysis of histone modifications. Our evaluation of different search engines on identifying histone modifications will hopefully help those who are hoping to enter the histone proteomics field. The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium with the data set identifier PXD001118.

Performance and component frontal areas of a hypothetical two-spool turbojet engine for three modes of operation

NASA Technical Reports Server (NTRS)

Dugan, James F , Jr

1955-01-01

Engine performance is better for constant outer-spool mechanical-speed operation than for constant inner-spool mechanical-speed operation over most of the flight range considered. Combustor and afterburner frontal areas are about the same for the two modes. Engine performance for a mode characterized by a constant outer-spool equivalent speed over part of the flight range and a constant outer-spool mechanical speed over the rest of the flight range is better that that for constant outer-spool mechanical speed operation. The former mode requires larger outer-spool centrifugal stresses and larger component frontal areas.

Speed limits set lower than engineering recommendations : project summary report.

DOT National Transportation Integrated Search

2016-08-01

The Montana Department of Transportation (MDT) generally ensures that posted speed limits are set in accordance with engineering recommendations, which means that speed limits are typically set such that they are about equal to the observed 85th-perc...

Increasing the reliability of labor of railroad engineers

NASA Technical Reports Server (NTRS)

Genes, V. S.; Madiyevskiy, Y. M.

1975-01-01

It has been shown that the group of problems related to temporary overloads still require serious development with respect to further automating the basic control operation - programmed selection of speed and braking. The problem of systems for warning the engineer about the condition of the unseen track segments remains a very serious one. Systems of hygenic support of the engineer also require constructive development. The problems of ensuring the reliability of work of engineers in periods of low information load, requiring motor acts, can basically be considered theoretically solved.

Martin B–26 Marauder at the Aircraft Engine Research Laboratory

NASA Image and Video Library

1943-09-21

The Aircraft Engine Research Laboratory’s first aircraft, a Martin B–26B Marauder, parked in front of the Flight Research Building in September 1943. The military loaned the B–26B to the National Advisory Committee for Aeronautics (NACA) to augment the lab’s studies of the Wright Aeronautical R–2800 engines. The military wanted to improve the engine cooling in order to increase the bomber’s performance. On March 17, 1943, the B–26B performed the very first research flight at the NACA’s new engine laboratory. The B–26B received its “Widowmaker” nickname during the rushed effort to transition the new aircraft from design to production and into the sky. During World War II, however, the B–26B proved itself to be a capable war machine. The U.S. lost fewer Marauders than any other type of bomber employed in the war. The B–26B was originally utilized at low altitudes in the Pacific but had its most success at high altitudes over Europe. The B–26B’s flight tests in Cleveland during 1943 mapped the R-2800 engine’s behavior at different altitudes and speeds. The researchers were then able to correlate engine performance in ground facilities to expected performance at different altitudes. They found that air speed, cowl flap position, angle of attack, propeller thrust, and propeller speed influenced inlet pressure recovery and exhaust distribution. The flight testing proceeded quickly, and the B–26B was transferred elsewhere in October 1943.

Altitude-Wind-Tunnel Investigation of the 19B-2, 19B-8, and 19XB-1 Jet-Propulsion Engines. II - Analysis of Turbine Performance of the 19B-8 Engine

NASA Technical Reports Server (NTRS)

Krebs, Richard P.; Suozzi, Frank L.

1947-01-01

Performance characteristics of the turbine in the 19B-8 jet propulsion engine were determined from an investigation of the complete engine in the Cleveland altitude wind tunnel. The investigation covered a range of simulated altitudes from 5000 to 30,000 feet and flight Mach numbers from 0.05 to 0.46 for various tail-cone positions over the entire operable range of engine speeds. The characteristics of the turbine are presented as functions of the total-pressure ratio across the turbine and the turbine speed and the gas flow corrected to NACA standard atmospheric conditions at sea level. The effect of changes in altitude, flight Mach number, and tail-cone position on turbine performance is discussed. The turbine efficiency with the tail cone in varied from a maximum of 80.5 percent to minimum of 75 percent over a range of engine speeds from 7500 to 17,500 rpm at a flight Mach number of 0.055. Turbine efficiency was unaffected by changes in altitude up to 15,000 feet but was a function of tail-cone position and flight Mach number. Decreasing the tail-pipe-nozzle outlet area 21 percent reduced the turbine efficiency between 2 and 4.5 percent. The turbine efficiency increased between 1.5 and 3 percent as the flight Mach number changed from 0.055 to 0.297.

Design Study of Propulsion and Drive Systems for the Large Civil TiltRotor (LCTR2) Rotorcraft

NASA Technical Reports Server (NTRS)

Robuck, Mark; Wilkerson, Joseph; Zhang, Yiyi; Snyder, Christopher A.; Vonderwell, Daniel

2013-01-01

Boeing, Rolls Royce, and NASA have worked together to complete a parametric sizing study for NASA's Large Civil Tilt Rotor (LCTR2) concept 2nd iteration. Vehicle gross weight and fuel usage were evaluated as propulsion and drive system characteristics were varied to maximize the benefit of reduced rotor tip speed during cruise conditions. The study examined different combinations of engine and gearbox variability to achieve rotor cruise tip speed reductions down to 54% of the hover tip speed. Previous NASA studies identified that a 54% rotor speed reduction in cruise minimizes vehicle gross weight and fuel burn. The LCTR2 was the study baseline for initial sizing. This study included rotor tip speed ratios (cruise to hover) of 100%, 77% and 54% at different combinations of engine RPM and gearbox speed reductions, which were analyzed to achieve the lightest overall vehicle gross weight (GW) at the chosen rotor tip speed ratio. Different engine and gearbox technology levels are applied ranging from commercial off-the-shelf (COTS) engines and gearbox technology to entry-in-service (EIS) dates of 2025 and 2035 to assess the benefits of advanced technology on vehicle gross weight and fuel burn. Interim results were previously reported1. This technical paper extends that work and summarizes the final study results including additional engine and drive system study accomplishments. New vehicle sizing data is presented for engine performance at a single operating speed with a multispeed drive system. Modeling details for LCTR2 vehicle sizing and subject engine and drive sub-systems are presented as well. This study was conducted in support of NASA's Fundamental Aeronautics Program, Subsonic Rotary Wing Project.

Small-scale heat detection using catalytic microengines irradiated by laser

NASA Astrophysics Data System (ADS)

Liu, Zhaoqian; Li, Jinxing; Wang, Jiao; Huang, Gaoshan; Liu, Ran; Mei, Yongfeng

2013-01-01

We demonstrate a novel approach to modulating the motion speed of catalytic microtubular engines via laser irradiation/heating with regard to small-scale heat detection. Laser irradiation on the engines leads to a thermal heating effect and thus enhances the engine speed. During a laser on/off period, the motion behaviour of a microengine can be repeatable and reversible, demonstrating a regulation of motion speeds triggered by laser illumination. Also, the engine velocity exhibits a linear dependence on laser power in various fuel concentrations, which implies an application potential as local heat sensors. Our work may hold great promise in applications such as lab on a chip, micro/nano factories, and environmental detection.We demonstrate a novel approach to modulating the motion speed of catalytic microtubular engines via laser irradiation/heating with regard to small-scale heat detection. Laser irradiation on the engines leads to a thermal heating effect and thus enhances the engine speed. During a laser on/off period, the motion behaviour of a microengine can be repeatable and reversible, demonstrating a regulation of motion speeds triggered by laser illumination. Also, the engine velocity exhibits a linear dependence on laser power in various fuel concentrations, which implies an application potential as local heat sensors. Our work may hold great promise in applications such as lab on a chip, micro/nano factories, and environmental detection. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr32494f

Performance of fuel system at different diesel temperature

NASA Astrophysics Data System (ADS)

Xu, Xiaoyong; Li, Xiaolu; Sun, Zai

2010-08-01

This paper presents the findings about performance of the fuel system of a diesel engine at different diesel temperature obtained through simulation and experiment. It can be seen from these findings that at the same rotational speed of fuel pump, the initial pressure in the fuel pipe remain unchanged as the fuel temperature increases, the peak pressure at the side of fuel pipe near the injector delays, and its largest value of pressure decreases. Meanwhile, at the same temperature, as the rotational speed increases, the initial pressure of fuel pipe is also essentially the same, the arrival of its peaks delays, and its largest value of pressure increases. The maximum fuel pressure at the side of fuel pipe near the injector has an increase of 28.9 %, 22.3%, and 13.9% respectively than the previous ones according to its conditions. At the same rotational speed, as the temperature increases, the injection quantity through the nozzle orifice decreases. At the same temperature, as the rotational speed increases, the injection quantity through the nozzle orifice increases. These experimental results are consistent with simulation results.

VSTOL tilt nacelle aerodynamics and its relation to fan blade stresses

NASA Technical Reports Server (NTRS)

Shaw, R. J.; Williams, R. C.; Koncsek, J. L.

1978-01-01

A scale model of a VSTOL tilt nacelle with a 0.508 m single stage fan was tested in a low speed wind tunnel to ascertain inlet aerodynamic and fan aeromechanical performance over the low speed flight envelope. Fan blade stress maxima occurred at discrete rotational speeds corresponding to integral engine order vibrations of the first flatwise bending mode. Increased fan blade stress levels coincided with internal boundary layer separation but became severe only when the separation location had progressed to the entry lip region of the inlet.

Knock-Limited Performance of Triptane and 28-R Fuel Blends as Affected by Changes in Compression Ratio and in Engine Operating Variables

NASA Technical Reports Server (NTRS)

Brun, Rinaldo J.; Feder, Melvin S.; Fisher, William F.

1947-01-01

A knock-limited performance investigation was conducted on blends of triptane and 28-P fuel with a 12-cylinder, V-type, liquid-cooled aircraft engine of 1710-cubic-inch displacement at three compression ratios: 6.65, 7.93, and 9.68. At each compression ratio, the effect of changes in temperature of the inlet air to the auxiliary-stage supercharger and in fuel-air ratio were investigated at engine speeds of 2280 and. 3000 rpm. The results show that knock-limited engine performance, as improved by the use of triptane, allowed operation at both take-off and cruising power at a compression ratio of 9.68. At an inlet-air temperature of 60 deg F, an engine speed of 3000 rpm ; and a fuel-air ratio of 0,095 (approximately take-off conditions), a knock-limited engine output of 1500 brake horsepower was possible with 100-percent 28-R fuel at a compression ratio of 6.65; 20-percent triptane was required for the same power output at a compression ratio of 7.93, and 75 percent at a compression ratio of 9.68 allowed an output of 1480 brake horsepower. Knock-limited power output was more sensitive to changes in fuel-air ratio as the engine speed was increased from 2280 to 3000 rpm, as the compression ratio is raised from 6.65 to 9.68, or as the inlet-air temperature is raised from 0 deg to 120 deg F.

JT8D-100 turbofan engine, phase 1. [noise reduction

NASA Technical Reports Server (NTRS)

1974-01-01

The JT8D turbofan engine, widely used in short and medium range transport aircraft, contributes substantially to airport community noise. The jet noise is predominant in the JT8D engine and may be reduced in a modified engine, without loss of thrust, by increasing the airflow to reduce jet velocity. A configuration study evaluated the effects of fan airflow, fan pressure ratio, and bypass ratio on noise, thrust, and fuel comsumption. The cycle selected for the modified engine was based upon an increased diameter, single-stage fan and two additional core engine compressor stages, which replace the existing two-stage fan. Modifications were also made to the low pressure turbine to provide the increased torque required by the larger diameter fan. The resultant JT8D-100 engine models have the following characteristics at take-off thrust, compared to the current JT8D engine: Airflow and bypass ratio are increased, and fan pressure ratio and engine speed are reduced. The resultant engine is also longer, larger in diameter, and heavier than the JT8D base model, but these latter changes are compensated by the increased thrust and decreased fuel comsumption of the modified engine, thus providing the capability for maintaining the performance of the current JT8D-powered aircraft.

Engineering studies in support of the development of high-speed track geometry specifications

DOT National Transportation Integrated Search

1997-03-01

The Federal Railroad Administration has been directing engineering studies to support the development of high speed track geometry standards. These standards are intended to cover train operating speeds from 110 mph to 200 mph. The studies conducted ...

Analysis of automobile engine cylinder pressure and rotation speed from engine body vibration signal

NASA Astrophysics Data System (ADS)

Wang, Yuhua; Cheng, Xiang; Tan, Haishu

2016-01-01

In order to improve the engine vibration signal process method for the engine cylinder pressure and engine revolution speed measurement instrument, the engine cylinder pressure varying with the engine working cycle process has been regarded as the main exciting force for the engine block forced vibration. The forced vibration caused by the engine cylinder pressure presents as a low frequency waveform which varies with the cylinder pressure synchronously and steadily in time domain and presents as low frequency high energy discrete humorous spectrum lines in frequency domain. The engine cylinder pressure and the rotation speed can been extract form the measured engine block vibration signal by low-pass filtering analysis in time domain or by FFT analysis in frequency domain, the low-pass filtering analysis in time domain is not only suitable for the engine in uniform revolution condition but also suitable for the engine in uneven revolution condition. That provides a practical and convenient way to design motor revolution rate and cylinder pressure measurement instrument.

Comparison of Communication Architectures and Network Topologies for Distributed Propulsion Controls (Preprint)

DTIC Science & Technology

2013-05-01

logic to perform control function computations and are connected to the full authority digital engine control ( FADEC ) via a high-speed data...Digital Engine Control ( FADEC ) via a high speed data communication bus. The short term distributed engine control configu- rations will be core...concen- trator; and high temperature electronics, high speed communication bus between the data concentrator and the control law processor master FADEC

Recent Efforts and Experiments in the Construction of Aviation Engines

NASA Technical Reports Server (NTRS)

SCHWAGER

1920-01-01

It became evident during World War I that ever-increasing demands were being placed on the mean power of aircraft engines as a result of the increased on board equipment and the demands of aerial combat. The need was for increased climbing efficiency and climbing speed. The response to these demands has been in terms of lightweight construction and the adaptation of the aircraft engine to the requirements of its use. Discussed here are specific efforts to increase flying efficiency, such as reduction of the number of revolutions of the propeller from 1400 to about 900 r.p.m. through the use of a reduction gear, increasing piston velocity, locating two crankshafts in one gear box, and using the two-cycle stroke. Also discussed are improvements in the transformation of fuel energy into engine power, the raising of compression ratios, the use of super-compression with carburetors constructed for high altitudes, the use of turbo-compressors, rotary engines, and the use of variable pitch propellers.

Fuel conservation evaluation of US (United States) Army helicopters. Part 4. OH-58C flight testing. Final report 22 Sep 20-Nov 82

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

Belte, D.; Stratton, M.V.

1982-08-01

The United States Army Aviation Engineering Flight Activity conducted level flight performance tests of the OH-58C helicopter at Edwards AFB, California from 22 September to 20 November 1981, and at St. Paul, Minnesota, from 12 January to 9 February 1982. Nondimensional methods were used to identify effects of compressibility and blade stall on performance, and increased referred rotor speeds were used to supplement the range of currently available level flight data. Maximum differences in nondimensional power required attributed to compressibility effects varied from 6.5 to 11%. However, high actual rotor speed at a given condition can result in less powermore » required than at low rotor speed even with the compressibility penalty. The power required characteristics determined by these tests can be combined with engine performance to determine the most fuel efficient operating conditions.« less

Applications of Endothermic Reaction Technology to the High Speed Civil Transport

NASA Technical Reports Server (NTRS)

Glickstein, Marvin R.; Spadaccini, Louis J.

1998-01-01

The success of strategies for controlling emissions and enhancing performance in High Speed Research applications may be Increased by more effective utilization of the heat sink afforded by the fuel in the vehicle thermal management system. This study quantifies the potential benefits associated with the use of supercritical preheating and endothermic cracking of let fuel prior to combustion to enhance the thermal management capabilities of the propulsion systems in the High Speed Civil Transport (HSCT). A fuel-cooled thermal management system, consisting of plate-fin heat exchangers and a small auxiliary compressor, is defined for the HSCT, Integrated with the engine, and an assessment of the effect on engine performance, weight, and operating cost is performed. The analysis indicates significant savings due a projected improvement in fuel economy, and the potential for additional benefit if the cycle is modified to take full advantage of all the heat sink available in the fuel.

Compression Ratio Adjuster

NASA Technical Reports Server (NTRS)

Akkerman, J. W.

1982-01-01

New mechanism alters compression ratio of internal-combustion engine according to load so that engine operates at top fuel efficiency. Ordinary gasoline, diesel and gas engines with their fixed compression ratios are inefficient at partial load and at low-speed full load. Mechanism ensures engines operate as efficiently under these conditions as they do at highload and high speed.

Mass spectral chemical fingerprints reveal the molecular dependence of exhaust particulate matters on engine speeds.

PubMed

Li, Yi; Zhang, Hua; Zhao, Zongshan; Tian, Yong; Liu, Kun; Jie, Feifan; Zhu, Liang; Chen, Huanwen

2018-05-01

Particulate matters (PMs) emitted by automobile exhaust contribute to a significant fraction of the global PMs. Extractive atmospheric pressure chemical ionization mass spectrometry (EAPCI-MS) was developed to explore the molecular dependence of PMs collected from exhaust gases produced at different vehicle engine speeds. The mass spectral fingerprints of the organic compounds embedded in differentially sized PMs (e.g., 0.22-0.45, 0.45-1.00, 1.00-2.00, 2.00-3.00, 3.00-5.00, and 5.00-10.00μm) generated at different engine speeds (e.g., 1000, 1500, 2000, 2500, and 3000r/min) were chemically profiled in the mass range of mass to charge ratio (m/z) 50-800. Organic compounds, including alcohols, aldehydes, and esters, were detected in all the PMs tested, with varied concentration levels for each individual PM sample. At relatively low engine speeds (≤1500r/min), the total amount of organic species embedded in PMs of 0.22-1.00μm was greater than in PMs of other sizes, while more organic species were found in PMs of 5.00-10.00μm at high engine speeds (≥3000r/min), indicating that the organic compounds distributed in different sizes of PMs strongly correlated with the engine speed. The experimental data showed that the EAPCI-MS technique enables molecular characterization of PMs in exhaust, revealing the chemical dependence of PMs on the engine speeds (i.e., the combustion conditions) of automobiles. Copyright © 2017. Published by Elsevier B.V.

Modeling Parasitic Energy Losses and the Impact of Advanced Tribological Concepts on Fuel Efficiency - Final CRADA Report

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

Fenske, George

2016-11-28

Our primary task for this project was to perform FMEP calculations for a broad range of parameters including engine type [spark ignition (SI) or compression ignition (CI)], engine size, engine mode (speed and load), lubricant viscosity, asperity friction, surface finish, oil type (mineral or synthetic), and additive (friction modifier), as discussed previously [1–3]. The actual analysis was limited to a large diesel engine and it included both load and speed dependencies as well as lubricant viscosity and speed.

Cooling Characteristics of a 2-Row Radial Engine

NASA Technical Reports Server (NTRS)

Schey, Oscar W; Rollin, Vern G

1937-01-01

This report presents the results of cooling tests conducted on a calibrated GR-1535 Pratt and Whitney Wasp, Jr. Engine installed in a Vought X04U-2 airplane. The tests were made in the NACA full-scale tunnel at air speeds from 70 to 120 miles per hour, at engine speeds from 1,500 to 2,600 r.p.m., and at manifold pressures from 19 to 33 inches of mercury absolute. A Smith controllable propeller was used to facilitate obtaining the different combinations of engine speed, power, and manifold pressure.

Interior noise levels of two propeller-driven light aircraft

NASA Technical Reports Server (NTRS)

Catherines, J. J.; Mayes, W. H.

1975-01-01

The relationships between aircraft operating conditions and interior noise and the degree to which ground testing can be used in lieu of flight testing for performing interior noise research were studied. The results show that the noise inside light aircraft is strongly influenced by the rotational speed of the engine and propeller. Both the overall noise and low frequency spectra levels were observed to decrease with increasing high speed rpm operations during flight. This phenomenon and its significance is not presently understood. Comparison of spectra obtained in flight with spectra obtained on the ground suggests that identification of frequency components and relative amplitude of propeller and engine noise sources may be evaluated on stationary aircraft.

Impact of methanol-gasoline fuel blend on the fuel consumption and exhaust emission of a SI engine

NASA Astrophysics Data System (ADS)

Rifal, Mohamad; Sinaga, Nazaruddin

2016-04-01

In this study, the effect of methanol-gasoline fuel blend (M15, M30 and M50) on the fuel consumption and exhaust emission of a spark ignition engine (SI) were investigated. In the experiment, an engine four-cylinder, four stroke injection system (engine of Toyota Kijang Innova 1TR-FE) was used. Test were did to know the relation of fuel consumption and exhaust emission (CO, CO2, HC) were analyzed under the idle throttle operating condition and variable engine speed ranging from 1000 to 4000 rpm. The experimental result showed that the fuel consumption decrease with the use of methanol. It was also shown that the CO and HC emission were reduced with the increase methanol content while CO2 were increased.

Future fuels and engines for railroad locomotives. Volume 1: Summary

NASA Technical Reports Server (NTRS)

Liddle, S. G.; Bonzo, B. B.; Purohit, G. P.; Stallkamp, J. A.

1981-01-01

The potential for reducing the dependence of railroads on petroleum fuel, particularly Diesel No. 2 was investigated. Two approaches are studied: (1) to determine how the use of Diesel No. 2 can be reduced through increased efficiency and conservation, and (2) to use fuels other than Diesel No. 2 both in Diesel and other types of engines. Because synthetic hydrocarbon fuels are particularly suited to medium speed diesel engines, the first commercial application of these fuels may be by the railroad industry.

Modeling of Engine Parameters for Condition-Based Maintenance of the MTU Series 2000 Diesel Engine

DTIC Science & Technology

2016-09-01

are suitable. To model the behavior of the engine, an autoregressive distributed lag (ARDL) time series model of engine speed and exhaust gas... time series model of engine speed and exhaust gas temperature is derived. The lag length for ARDL is determined by whitening of residuals using the...15 B. REGRESSION ANALYSIS ....................................................................15 1. Time Series Analysis

Mathematical model of marine diesel engine simulator for a new methodology of self propulsion tests

NASA Astrophysics Data System (ADS)

Izzuddin, Nur; Sunarsih, Priyanto, Agoes

2015-05-01

As a vessel operates in the open seas, a marine diesel engine simulator whose engine rotation is controlled to transmit through propeller shaft is a new methodology for the self propulsion tests to track the fuel saving in a real time. Considering the circumstance, this paper presents the real time of marine diesel engine simulator system to track the real performance of a ship through a computer-simulated model. A mathematical model of marine diesel engine and the propeller are used in the simulation to estimate fuel rate, engine rotating speed, thrust and torque of the propeller thus achieve the target vessel's speed. The input and output are a real time control system of fuel saving rate and propeller rotating speed representing the marine diesel engine characteristics. The self-propulsion tests in calm waters were conducted using a vessel model to validate the marine diesel engine simulator. The simulator then was used to evaluate the fuel saving by employing a new mathematical model of turbochargers for the marine diesel engine simulator. The control system developed will be beneficial for users as to analyze different condition of vessel's speed to obtain better characteristics and hence optimize the fuel saving rate.

Scramjet nozzle design and analysis as applied to a highly integrated hypersonic research airplane

NASA Technical Reports Server (NTRS)

Small, W. J.; Weidner, J. P.; Johnston, P. J.

1976-01-01

Engine-nozzle airframe integration at hypersonic speeds was conducted by using a high-speed research aircraft concept as a focus. Recently developed techniques for analysis of scramjet-nozzle exhaust flows provide a realistic analysis of complex forces resulting from the engine-nozzle airframe coupling. By properly integrating the engine-nozzle propulsive system with the airframe, efficient, controlled and stable flight results over a wide speed range.

Flame Acceleration and Transition to Detonation in High-Speed Turbulent Combustion

DTIC Science & Technology

2016-12-21

Turbulent Combustion 1. Introduction to the Challenge Problem The importance of high-speed t urbulent combustion of gas mixtures and sprays is dif...engines, gas turbines, various types of jet engines, and some rocket engines . On the other hand , preventing high-speed combustion is critical for...the safety of any human activities that involve handling of po- t entially explosive gases or volatile liquids . Thus, the development of more fuel

Identification and quantification analysis of nonlinear dynamics properties of combustion instability in a diesel engine

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

Yang, Li-Ping, E-mail: yangliping302@hrbeu.edu.cn; Ding, Shun-Liang; Song, En-Zhe

The cycling combustion instabilities in a diesel engine have been analyzed based on chaos theory. The objective was to investigate the dynamical characteristics of combustion in diesel engine. In this study, experiments were performed under the entire operating range of a diesel engine (the engine speed was changed from 600 to 1400 rpm and the engine load rate was from 0% to 100%), and acquired real-time series of in-cylinder combustion pressure using a piezoelectric transducer installed on the cylinder head. Several methods were applied to identify and quantitatively analyze the combustion process complexity in the diesel engine including delay-coordinate embedding, recurrencemore » plot (RP), Recurrence Quantification Analysis, correlation dimension (CD), and the largest Lyapunov exponent (LLE) estimation. The results show that the combustion process exhibits some determinism. If LLE is positive, then the combustion system has a fractal dimension and CD is no more than 1.6 and within the diesel engine operating range. We have concluded that the combustion system of diesel engine is a low-dimensional chaotic system and the maximum values of CD and LLE occur at the lowest engine speed and load. This means that combustion system is more complex and sensitive to initial conditions and that poor combustion quality leads to the decrease of fuel economy and the increase of exhaust emissions.« less

Identification and quantification analysis of nonlinear dynamics properties of combustion instability in a diesel engine.

PubMed

Yang, Li-Ping; Ding, Shun-Liang; Litak, Grzegorz; Song, En-Zhe; Ma, Xiu-Zhen

2015-01-01

The cycling combustion instabilities in a diesel engine have been analyzed based on chaos theory. The objective was to investigate the dynamical characteristics of combustion in diesel engine. In this study, experiments were performed under the entire operating range of a diesel engine (the engine speed was changed from 600 to 1400 rpm and the engine load rate was from 0% to 100%), and acquired real-time series of in-cylinder combustion pressure using a piezoelectric transducer installed on the cylinder head. Several methods were applied to identify and quantitatively analyze the combustion process complexity in the diesel engine including delay-coordinate embedding, recurrence plot (RP), Recurrence Quantification Analysis, correlation dimension (CD), and the largest Lyapunov exponent (LLE) estimation. The results show that the combustion process exhibits some determinism. If LLE is positive, then the combustion system has a fractal dimension and CD is no more than 1.6 and within the diesel engine operating range. We have concluded that the combustion system of diesel engine is a low-dimensional chaotic system and the maximum values of CD and LLE occur at the lowest engine speed and load. This means that combustion system is more complex and sensitive to initial conditions and that poor combustion quality leads to the decrease of fuel economy and the increase of exhaust emissions.

Multifidelity, multidisciplinary optimization of turbomachines with shock interaction

NASA Astrophysics Data System (ADS)

Joly, Michael Marie

Research on high-speed air-breathing propulsion aims at developing aircraft with antipodal range and space access. Before reaching high speed at high altitude, the flight vehicle needs to accelerate from takeoff to scramjet takeover. Air turbo rocket engines combine turbojet and rocket engine cycles to provide the necessary thrust in the so-called low-speed regime. Challenges related to turbomachinery components are multidisciplinary, since both the high compression ratio compressor and the powering high-pressure turbine operate in the transonic regime in compact environments with strong shock interactions. Besides, lightweight is vital to avoid hindering the scramjet operation. Recent progress in evolutionary computing provides aerospace engineers with robust and efficient optimization algorithms to address concurrent objectives. The present work investigates Multidisciplinary Design Optimization (MDO) of innovative transonic turbomachinery components. Inter-stage aerodynamic shock interaction in turbomachines are known to generate high-cycle fatigue on the rotor blades compromising their structural integrity. A soft-computing strategy is proposed to mitigate the vane downstream distortion, and shown to successfully attenuate the unsteady forcing on the rotor of a high-pressure turbine. Counter-rotation offers promising prospects to reduce the weight of the machine, with fewer stages and increased load per row. An integrated approach based on increasing level of fidelity and aero-structural coupling is then presented and allows achieving a highly loaded compact counter-rotating compressor.

Evaluation of different rotary devices on bone repair in rabbits.

PubMed

Ribeiro Junior, Paulo Domingos; Barleto, Christiane Vespasiano; Ribeiro, Daniel Araki; Matsumoto, Mariza Akemi

2007-01-01

In oral surgery, the quality of bone repair may be influenced by several factors that can increase the morbidity of the procedure. The type of equipment used for ostectomy can directly affect bone healing. The aim of this study was to evaluate bone repair of mandible bone defects prepared in rabbits using three different rotary devices. Fifteen New Zealand rabbits were randomly assigned to 3 groups (n=5) according to type of rotary device used to create bone defects: I--pneumatic low-speed rotation engine, II--pneumatic high-speed rotation engine, and III--electric low-speed rotation engine. The anatomic pieces were surgically obtained after 2, 7 and 30 days and submitted to histological and morphometric analysis. The morphometric results were expressed as the total area of bone remodeling matrix using an image analysis system. Increases in the bone remodeling matrix were noticed with time along the course of the experiment. No statistically significant differences (p>0.05) were observed among the groups at the three sacrificing time points considering the total area of bone mineralized matrix, although the histological analysis showed a slightly advanced bone repair in group III compared to the other two groups. The findings of the present study suggest that the type of rotary device used in oral and maxillofacial surgery does not interfere with the bone repair process.

Tablet PCs in Engineering Mathematics Courses at the J.B. Speed School of Engineering

ERIC Educational Resources Information Center

Hieb, Jeffrey L.; Ralston, Patricia A. S.

2010-01-01

In fall 2007, J.B. Speed School of Engineering at the University of Louisville joined the ranks of universities requiring the purchase of Tablet PCs for all new entering students. This article presents a description of how the Department of Engineering Fundamentals incorporated Tablet PCs into their instruction, a review of the literature…

Performance of 4600-pound-thrust centrifugal-flow-type turbojet engine with water-alcohol injection at inlet

NASA Technical Reports Server (NTRS)

Glasser, Philip W

1950-01-01

An experimental investigation of the effects of injecting a water-alcohol mixture of 2:1 at the compressor inlet of a centrifugal-flow type turbojet engine was conducted in an altitude test chamber at static sea-level conditions and at an altitude of 20,000 feet with a flight Mach number of 0.78 with an engine operating at rated speed. The net thrust was augmented by 0.16 for both flight conditions with a ratio of injected liquid to air flow of 0.05. Further increases in the liquid-air ratio did not give comparable increases in thrust.

Relative performance comparison between baseline labyrinth and dual-brush compressor discharge seals in a T-700 engine test

NASA Technical Reports Server (NTRS)

Hendricks, Robert C.; Griffin, Thomas A.; Kline, Teresa R.; Csavina, Kristine R.; Pancholi, Arvind; Sood, Devendra

1995-01-01

In separate series of YT-700 engine tests, direct comparisons were made between the forward-facing labyrinth and dual brush compressor discharge seals. Compressor speeds to 43 000 rpm, surface speeds to 160 m/s (530 ft/s), pressures to 1 MPa (145 psi), and temperatures to 680 K (765 F) characterized these tests. The wear estimate for 46 hr of engine operations was less than 0.025 mm (0.001 in.) of the Haynes 25 alloy bristles running against a chromium-carbide-coated rub runner. The pressure drops were higher for the dual-brush seal than for the forward-facing labyrinth seal and leakage was lower-with the labyrinth seal leakage being 2-1/2 times greater-implying better seal characteristics, better secondary airflow distribution, and better engine performance (3 percent at high pressure to 5 percent at lower pressure) for the brush seal. (However, as brush seals wear down (after 500 to 1000 hr of engine operation), their leakage rates will increase.) Modification of the secondary flow path requires that changes in cooling air and engine dynamics be accounted for.

The Potential Benefits of Advanced Casing Treatment for Noise Attenuation in Utra-High Bypass Ratio Turbofan Engines

NASA Technical Reports Server (NTRS)

Elliott, David

2007-01-01

In order to increase stall margin in a high-bypass ratio turbofan engine, an advanced casing treatment was developed that extracted a small amount of flow from the casing behind the fan and injected it back in front of the fan. Several different configurations of this casing treatment were designed by varying the distance of the extraction and injection points, as well as varying the amount of flow. These casing treatments were tested on a 55.9 cm (22 in.) scale model of the Pratt & Whitney Advanced Ducted Propulsor in the NASA Glenn 9 by 15 Low Speed Wind Tunnel. While all of the casing treatment configurations showed the expected increase in stall margin, a few of the designs showed a potential noise benefit for certain engine speeds. This paper will show the casing treatments and the results of the testing as well as propose further research in this area. With better prediction and design techniques, future casing treatment configurations could be developed that may result in an optimized casing treatment that could conceivably reduce the noise further.

A study on the structural characteristics and shape of outfitting equipment support in 300K DWT crude oil tanker

NASA Astrophysics Data System (ADS)

Jeong, K.; Jeong, H.; Ji, M.; Kim, J.; Park, J.; Chung, H.

2015-09-01

With the increase in the size and speed of recently built vessels, the output and speed (rpm) of propulsion or generation engines have continuously increased, and the high-output, highspeed engine has become a major cause of excessive vessel noise and vibration. Accordingly, resonance occurs in the equipment and other outfitting equipment installed in a vessel, and thus, periodic requests for correction are received from ship owners or officers. In this study, to resolve this problem, supports that stably fix the outfitting equipment installed in the engine room of a very large crude oil tanker and provide protection from physical or external shock were classified into seven types for three kinds of widely used standard shapes, and an optimized shape was developed and suggested by analyzing the structural characteristics of the shapes of the supports (the maximum bending moment, maximum bending stress, and maximum deformation) using DNV NATICUS HULL 3D BEAM, a structural analysis program, so that it could be used for the outfitting design of a vessel.

40 CFR 92.116 - Engine output measurement system calibrations.

Code of Federal Regulations, 2014 CFR

2014-07-01

... calibration. (1) The engine flywheel torque and engine speed measurement transducers shall be calibrated with... performed with the dynamometer operating at a constant speed. The flywheel torque measurement device readout... practice requires that both devices have approximately equal useful ranges of torque measurement.) The...

40 CFR 92.116 - Engine output measurement system calibrations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... calibration. (1) The engine flywheel torque and engine speed measurement transducers shall be calibrated with... performed with the dynamometer operating at a constant speed. The flywheel torque measurement device readout... practice requires that both devices have approximately equal useful ranges of torque measurement.) The...

40 CFR 92.116 - Engine output measurement system calibrations.

Code of Federal Regulations, 2011 CFR

2011-07-01

... calibration. (1) The engine flywheel torque and engine speed measurement transducers shall be calibrated with... performed with the dynamometer operating at a constant speed. The flywheel torque measurement device readout... practice requires that both devices have approximately equal useful ranges of torque measurement.) The...

40 CFR 92.116 - Engine output measurement system calibrations.

Code of Federal Regulations, 2012 CFR

2012-07-01

... calibration. (1) The engine flywheel torque and engine speed measurement transducers shall be calibrated with... performed with the dynamometer operating at a constant speed. The flywheel torque measurement device readout... practice requires that both devices have approximately equal useful ranges of torque measurement.) The...

Performance potential of an advanced technology Mach 3 turbojet engine installed on a conceptual high-speed civil transport

NASA Technical Reports Server (NTRS)

Morris, Shelby J., Jr.; Geiselhart, Karl A.; Coen, Peter G.

1989-01-01

The performance of an advanced technology conceptual turbojet optimized for a high-speed civil aircraft is presented. This information represents an estimate of performance of a Mach 3 Brayton (gas turbine) cycle engine optimized for minimum fuel burned at supersonic cruise. This conceptual engine had no noise or environmental constraints imposed upon it. The purpose of this data is to define an upper boundary on the propulsion performance for a conceptual commercial Mach 3 transport design. A comparison is presented demonstrating the impact of the technology proposed for this conceptual engine on the weight and other characteristics of a proposed high-speed civil transport. This comparison indicates that the advanced technology turbojet described could reduce the gross weight of a hypothetical Mach 3 high-speed civil transport design from about 714,000 pounds to about 545,000 pounds. The aircraft with the baseline engine and the aircraft with the advanced technology engine are described.

Life-Extending Control for Aircraft Engines Studied

NASA Technical Reports Server (NTRS)

Guo, Te-Huei

2002-01-01

Current aircraft engine controllers are designed and operated to provide both performance and stability margins. However, the standard method of operation results in significant wear and tear on the engine and negatively affects the on-wing life--the time between cycles when the engine must be physically removed from the aircraft for maintenance. The NASA Glenn Research Center and its industrial and academic partners have been working together toward a new control concept that will include engine life usage as part of the control function. The resulting controller will be able to significantly extend the engine's on-wing life with little or no impact on engine performance and operability. The new controller design will utilize damage models to estimate and mitigate the rate and overall accumulation of damage to critical engine parts. The control methods will also provide a means to assess tradeoffs between performance and structural durability on the basis of mission requirements and remaining engine life. Two life-extending control methodologies were studied to reduce the overall life-cycle cost of aircraft engines. The first methodology is to modify the baseline control logic to reduce the thermomechanical fatigue (TMF) damage of cooled stators during acceleration. To accomplish this, an innovative algorithm limits the low-speed rotor acceleration command when the engine has reached a threshold close to the requested thrust. This algorithm allows a significant reduction in TMF damage with only a very small increase in the rise time to reach the commanded rotor speed. The second methodology is to reduce stress rupture/creep damage to turbine blades and uncooled stators by incorporating an engine damage model into the flight mission. Overall operation cost is reduced by an optimization among the flight time, fuel consumption, and component damages. Recent efforts have focused on applying life-extending control technology to an existing commercial turbine engine, and doing so without modifying the hardware or adding sensors. This approach makes it possible to retrofit existing engines with life-extending control technology by changing only the control software in the full-authority digital engine controller (FADEC). The significant results include demonstrating a 20- to 30-percent reduction in TMF damage to the hot section by developing and implementing smart acceleration logic during takeoff. The tradeoff is an increase, from 5.0 to 5.2 sec, in the time required to reach maximum power from ground idle. On a typical flight profile of a cruise at Mach 0.8 at an altitude of 41,000 ft, and cruise time of 104 min, the optimized system showed that a reduction in cruise speed from Mach 0.8 to 0.79 can achieve an estimated 25-to 35-percent creep/rupture damage reduction in the engine's hot section and a fuel savings of 2.1 percent. The tradeoff is an increase in flight time of 1.3 percent (1.4 min).

Experimental investigation of regulated and unregulated emissions from a diesel engine fueled with ultralow-sulfur diesel fuel blended with ethanol and dodecanol

NASA Astrophysics Data System (ADS)

Cheung, C. S.; Di, Yage; Huang, Zuohua

Experiments were conducted on a four-cylinder direct-injection diesel engine using ultralow-sulfur diesel as the main fuel, ethanol as the oxygenate additive and dodecanol as the solvent, to investigate the regulated and unregulated emissions of the engine under five engine loads at an engine speed of 1800 rev min -1. Blended fuels containing 6.1%, 12.2%, 18.2% and 24.2% by volume of ethanol, corresponding to 2%, 4%, 6% and 8% by mass of oxygen in the blended fuel, were used. The results indicate that with an increase in ethanol in the fuel, the brake specific fuel consumption becomes higher while there is little change in the brake thermal efficiency. Regarding the regulated emissions, HC and CO increase significantly at low engine load but might decrease at high engine load, NO x emission slightly decreases at low engine load but slightly increases at high engine load, while particulate mass decreases significantly at high engine load. For the unregulated gaseous emissions, unburned ethanol and acetaldehyde increase but formaldehyde, ethene, ethyne, 1,3-butadiene and BTX (benzene, toluene and xylene) in general decrease, especially at high engine load. A diesel oxidation catalyst (DOC) is found to reduce significantly most of the pollutants, including the air toxics.

A Modular Aero-Propulsion System Simulation of a Large Commercial Aircraft Engine

NASA Technical Reports Server (NTRS)

DeCastro, Jonathan A.; Litt, Jonathan S.; Frederick, Dean K.

2008-01-01

A simulation of a commercial engine has been developed in a graphical environment to meet the increasing need across the controls and health management community for a common research and development platform. This paper describes the Commercial Modular Aero Propulsion System Simulation (C-MAPSS), which is representative of a 90,000-lb thrust class two spool, high bypass ratio commercial turbofan engine. A control law resembling the state-of-the-art on board modern aircraft engines is included, consisting of a fan-speed control loop supplemented by relevant engine limit protection regulator loops. The objective of this paper is to provide a top-down overview of the complete engine simulation package.

Design and Test of Fan/Nacelle Models Quiet High-Speed Fan

NASA Technical Reports Server (NTRS)

Miller, Christopher J. (Technical Monitor); Weir, Donald

2003-01-01

The Quiet High-Speed Fan program is a cooperative effort between Honeywell Engines & Systems (formerly AlliedSignal Engines & Systems) and the NASA Glenn Research Center. Engines & Systems has designed an advanced high-speed fan that will be tested on the Ultra High Bypass Propulsion Simulator in the NASA Glenn 9 x 15 foot wind tunnel, currently scheduled for the second quarter of 2000. An Engines & Systems modern fan design will be used as a baseline. A nacelle model is provided that is characteristic of a typical, modern regional aircraft nacelle and meets all of the program test objectives.

Quiet Clean Short-haul Experimental Engine (QCSEE) main reduction gears detailed design report

NASA Technical Reports Server (NTRS)

Defeo, A.; Kulina, M.

1977-01-01

Lightweight turbine engines with geared slower speed fans are considered. The design of two similar but different gear ratio, minimum weight, epicyclic star configuration main reduction gears for the under the wing (UTW) and over the wing (OTW) engines is discussed. The UTW engine reduction gear has a ratio of 2.465:1 and a 100% power design rating of 9885 kW (13,256 hp) at 3143 rpm fan speed. The OTW engine reduction gear has a ratio of 2.062:1 and a 100% power design rating of 12813 kW (17183 hp) at 3861 rpm fan speed. Details of configuration, stresses, deflections, and lubrication are presented.

Study on Stability of High Speed Traction Drive CVT for Aircraft Generator

NASA Astrophysics Data System (ADS)

Goi, Tatsuhiko; Tanaka, Hirohisa; Nakashima, Kenichi; Watanabe, Koji

A half-toroidal traction drive CVT has a feature of small spin at traction pitch in whole speed ratio range of 1:4, which suits to transmit high rotational speed with minimum temperature increase of traction surface. Research activity on traction drive CVT has commenced in 1996 for applying it to an aircraft 24,000rpm constant-speed generator instead of a hydro-static transmission. This paper shows fundamental design of 90kW traction drive integrated drive generator, ``T-IDG", and stability analysis on a sensor-less electro-hydraulic speed control servo-mechanism by bond graphs. The performance test of T-IDG mounted on a test bench and an actual jet engine proved that the control system using sensor-less servomechanism can keep the generator speed within MIL-STD-704E allowable limit against steep changes of speed and load.

Study on the combustion process in a modern diesel engine controlled by pre-injection strategy

NASA Astrophysics Data System (ADS)

Punov, P.; Milkov, N.; Perilhon, C.; Podevin, P.; Evtimov, T.

2017-10-01

The paper aims to study the combustion process in a modern diesel engine over the engine operating map. In order to study the rate of heat release (ROHR), an automotive diesel engine was experimentally tested using the injection parameters factory defined. The experimental test was conducted over the engine operating map as the engine speed was limited to 2400 rpm. Then, an engine simulation model was developed in AVL Boost. By means of that model the ROHR was estimated and approximated by means of double Vibe function. In all engine operating points we found two peaks at the ROHR. The first is a result of the pilot injection as the second corresponds to the main injection. There was not found an overlap between both peaks. It was found that the first peak of ROHR occurs closely before top dead center (BTDC) at partial load than full load. The ROHR peak as a result of main injection begins from 4°BTDC to 18°ATDC. It starts earlier with increasing engine speed and load. The combustion duration varies from 30 ºCA to 70 °CA. In order to verify the results pressure curve was estimated by means of defined Vibe function parameters and combustion duration. As a result, we observed small deviation between measured and simulated pressure curves.

Fan noise control using Herschel-Quincke resonators on a production turbofan engine

NASA Astrophysics Data System (ADS)

Burdisso, Ricardo A.; Gerhold, Carl H.

2002-05-01

The Herschel-Quincke (HQ) resonator concept is an innovative technique that consists of installing circumferential arrays of HQ waveguides around the inlet of a turbofan engine. An HQ waveguide is essentially a hollow side tube that travels along (but not necessarily parallel to) the engine axis and attaches to the inlet at each of the two ends of the tube. To investigate the potential of the concept, the approach was tested on a full-scale production Honeywell TFE731-60 engine. An HQ-inlet system containing two arrays was designed to attenuate the blade passage frequency (BPF) tone at approach condition, i.e., 60% engine power. However, the system was tested over the full range of engine power settings. The effects of each array both individually and together were evaluated as compared to the hard-wall case. Both far-field and induct data were recorded during the tests. The results show good attenuation of both the BPF tone and broadband components. Furthermore, reduction of ``buzz-saw'' tones, i.e., additional tones radiated from the inlet when the fan-tip speed goes supersonic, was observed with the HQ system. Some fan distortion effects and increase in noise was observed at higher engine speeds. [Work supported by NASA Langley Research Center.

Comparative effects of MTBE and ethanol additions into gasoline on exhaust emissions

NASA Astrophysics Data System (ADS)

Song, Chong-Lin; Zhang, Wen-Mei; Pei, Yi-Qiang; Fan, Guo-Liang; Xu, Guan-Peng

The effects of the additives of ethanol (EA) and methyl tert-butyl ether (MTBE) in various blend ratios into the gasoline fuel on the exhaust emissions and the catalytic conversion efficiencies were investigated in an EFI gasoline engine. The regulated exhaust emissions (CO, THC and NO X) and the unregulated exhaust emissions (benzene, formaldehyde, acetaldehyde, unburned EA and MTBE) before and after the three-way catalytic converter were measured. The experimental results showed that EA brought about generally lower regulated engine-out emissions than MTBE did. But, the comparison of the unregulated engine-out emissions between both additives was different. Concretely, the effect of EA on benzene emission was worse than that of MTBE on the whole, which was a contrast with formaldehyde emission. The difference in the acetaldehyde comparison depended much on the engine operating conditions, especially the engine speed. Both EA and MTBE were identified in the engine exhaust gases only when they were added to the fuel, and their volume fraction increased with blend ratios. The catalytic conversion efficiencies of the regulated emissions for the EA blends were in general lower than those for MTBE blends, especially at the low and high engine speeds. There was little difference in the catalytic conversion efficiencies for both benzene and formaldehyde, while distinct difference for acetaldehyde.

Double-reed exhaust valve engine

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

Bennett, Charles L.

An engine based on a reciprocating piston engine that extracts work from pressurized working fluid. The engine includes a double reed outlet valve for controlling the flow of low-pressure working fluid out of the engine. The double reed provides a stronger force resisting closure of the outlet valve than the force tending to open the outlet valve. The double reed valve enables engine operation at relatively higher torque and lower efficiency at low speed, with lower torque, but higher efficiency at high speed.

A Comparative Propulsion System Analysis for the High-Speed Civil Transport

NASA Technical Reports Server (NTRS)

Berton, Jeffrey J.; Haller, William J.; Senick, Paul F.; Jones, Scott M.; Seidel, Jonathan A.

2005-01-01

Six of the candidate propulsion systems for the High-Speed Civil Transport are the turbojet, turbine bypass engine, mixed flow turbofan, variable cycle engine, Flade engine, and the inverting flow valve engine. A comparison of these propulsion systems by NASA's Glenn Research Center, paralleling studies within the aircraft industry, is presented. This report describes the Glenn Aeropropulsion Analysis Office's contribution to the High-Speed Research Program's 1993 and 1994 propulsion system selections. A parametric investigation of each propulsion cycle's primary design variables is analytically performed. Performance, weight, and geometric data are calculated for each engine. The resulting engines are then evaluated on two airframer-derived supersonic commercial aircraft for a 5000 nautical mile, Mach 2.4 cruise design mission. The effects of takeoff noise, cruise emissions, and cycle design rules are examined.

75 FR 65399 - Petition for Waiver of Compliance

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-22

... determination that the engineering principles used in its design of its Continuous Speed Control Yard located at... states that the design elements of the Continuous Speed Control System meets American Railway Engineering... Section 2.4 of the AREMA Manual for Railway Engineering. UP also states that the design of Roseville yard...

49 CFR 213.305 - Designation of qualified individuals; general qualifications.

Code of Federal Regulations, 2013 CFR

2013-10-01

... college level engineering program, supplemented by special on the job training emphasizing the techniques... of high speed track provided by the employer or by a college level engineering program, supplemented... maintenance of high speed track provided by the employer or by a college level engineering program...

49 CFR 213.305 - Designation of qualified individuals; general qualifications.

Code of Federal Regulations, 2014 CFR

2014-10-01

... college level engineering program, supplemented by special on the job training emphasizing the techniques... of high speed track provided by the employer or by a college level engineering program, supplemented... maintenance of high speed track provided by the employer or by a college level engineering program...

49 CFR 213.305 - Designation of qualified individuals; general qualifications.

Code of Federal Regulations, 2012 CFR

2012-10-01

... college level engineering program, supplemented by special on the job training emphasizing the techniques... of high speed track provided by the employer or by a college level engineering program, supplemented... maintenance of high speed track provided by the employer or by a college level engineering program...

40 CFR Appendix III to Part 1042 - Not-to-Exceed Zones

Code of Federal Regulations, 2011 CFR

2011-07-01

... marine engines used with controllable-pitch propellers or with electrically coupled propellers, as... CONTROLS CONTROL OF EMISSIONS FROM NEW AND IN-USE MARINE COMPRESSION-IGNITION ENGINES AND VESSELS Pt. 1042... (or at Maximum Test Torque for constant-speed engines). (2) Percent speed means the percentage of...

40 CFR Appendix III to Part 1042 - Not-to-Exceed Zones

Code of Federal Regulations, 2010 CFR

2010-07-01

... marine engines used with controllable-pitch propellers or with electrically coupled propellers, as... CONTROLS CONTROL OF EMISSIONS FROM NEW AND IN-USE MARINE COMPRESSION-IGNITION ENGINES AND VESSELS Pt. 1042... (or at Maximum Test Torque for constant-speed engines). (2) Percent speed means the percentage of...

40 CFR Appendix III to Part 1042 - Not-to-Exceed Zones

Code of Federal Regulations, 2014 CFR

2014-07-01

... marine engines used with controllable-pitch propellers or with electrically coupled propellers, as... CONTROLS CONTROL OF EMISSIONS FROM NEW AND IN-USE MARINE COMPRESSION-IGNITION ENGINES AND VESSELS Pt. 1042... (or at Maximum Test Torque for constant-speed engines). (2) Percent speed means the percentage of...

40 CFR Appendix III to Part 1042 - Not-to-Exceed Zones

Code of Federal Regulations, 2013 CFR

2013-07-01

... marine engines used with controllable-pitch propellers or with electrically coupled propellers, as... CONTROLS CONTROL OF EMISSIONS FROM NEW AND IN-USE MARINE COMPRESSION-IGNITION ENGINES AND VESSELS Pt. 1042... (or at Maximum Test Torque for constant-speed engines). (2) Percent speed means the percentage of...

40 CFR Appendix III to Part 1042 - Not-to-Exceed Zones

Code of Federal Regulations, 2012 CFR

2012-07-01

... marine engines used with controllable-pitch propellers or with electrically coupled propellers, as... CONTROLS CONTROL OF EMISSIONS FROM NEW AND IN-USE MARINE COMPRESSION-IGNITION ENGINES AND VESSELS Pt. 1042... (or at Maximum Test Torque for constant-speed engines). (2) Percent speed means the percentage of...

14 CFR 23.149 - Minimum control speed.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Minimum control speed. 23.149 Section 23... Maneuverability § 23.149 Minimum control speed. (a) VMC is the calibrated airspeed at which, when the critical engine is suddenly made inoperative, it is possible to maintain control of the airplane with that engine...

Design of the low-speed NLF(1)-0414F and the high-speed HSNLF(1)-0213 airfoils with high-lift systems

NASA Technical Reports Server (NTRS)

Viken, Jeffrey K.; Watson-Viken, Sally A.; Pfenninger, Werner; Morgan, Harry L., Jr.; Campbell, Richard L.

1987-01-01

The design and testing of Natural Laminar Flow (NLF) airfoils is examined. The NLF airfoil was designed for low speed, having a low profile drag at high chord Reynolds numbers. The success of the low speed NLF airfoil sparked interest in a high speed NLF airfoil applied to a single engine business jet with an unswept wing. Work was also conducted on the two dimensional flap design. The airfoil was decambered by removing the aft loading, however, high design Mach numbers are possible by increasing the aft loading and reducing the camber overall on the airfoil. This approach would also allow for flatter acceleration regions which are more stabilizing for cross flow disturbances. Sweep could then be used to increase the design Mach number to a higher value also. There would be some degradation of high lift by decambering the airfoil overall, and this aspect would have to be considered in a final design.

Experimental investigation of regulated and unregulated emissions from a diesel engine fueled with Euro V diesel fuel and fumigation methanol

NASA Astrophysics Data System (ADS)

Zhang, Z. H.; Cheung, C. S.; Chan, T. L.; Yao, C. D.

2010-03-01

Experiments were conducted on a four-cylinder direct-injection diesel engine with part of the engine load taken up by fumigation methanol injected into the air intake of each cylinder to investigate the regulated and unregulated gaseous emissions and particulate emission of the engine under five engine loads at an engine speed of 1920 rev min -1. The fumigation methanol was injected to top up 10%, 20% and 30% of the engine load under different engine operating conditions. The experimental results show that at low engine loads, the brake thermal efficiency (BTE) decreases with increase in fumigation methanol; but at high engine loads, the BTE is not significantly affected by fumigation methanol. The fumigation methanol results in significant increase in hydrocarbon (HC), carbon monoxide (CO) and nitrogen dioxide (NO 2) emissions, but decrease in nitrogen oxides (NO x). For the unregulated gaseous emissions, unburned methanol, formaldehyde and BTX (benzene, toluene and xylene) emissions increase but ethyne, ethene and 1,3-butadiene emissions decrease. Particulate mass and number concentrations also decrease with increase in fumigation methanol. A diesel oxidation catalyst (DOC) is found to reduce significantly most of the pollutants, including the air toxics, when the exhaust gas temperature is sufficiently high.

A Stirling engine for use with lower quality fuels

NASA Astrophysics Data System (ADS)

Paul, Christopher J.

There is increasing interest in using renewable fuels from biomass or alternative fuels such as municipal waste to reduce the need for fossil based fuels. Due to the lower heating values and higher levels of impurities, small scale electricity generation is more problematic. Currently, there are not many technologically mature options for small scale electricity generation using lower quality fuels. Even though there are few manufacturers of Stirling engines, the history of their development for two centuries offers significant guidance in developing a viable small scale generator set using lower quality fuels. The history, development, and modeling of Stirling engines were reviewed to identify possible model and engine configurations. A Stirling engine model based on the finite volume, ideal adiabatic model was developed. Flow dissipation losses are shown to need correcting as they increase significantly at low mean engine pressure and high engine speed. The complete engine including external components was developed. A simple yet effective method of evaluating the external heat transfer to the Stirling engine was created that can be used with any second order Stirling engine model. A derivative of the General Motors Ground Power Unit 3 was designed. By significantly increasing heater, cooler and regenerator size at the expense of increased dead volume, and adding a combustion gas recirculation, a generator set with good efficiency was designed.

Vibration measurements of automobile catalyst

NASA Astrophysics Data System (ADS)

Aatola, Seppo

1994-09-01

Vibration of catalyst cell, which is inside the casing of the catalyst, is difficult to measure with usual measuring instrumentation. When catalyst is in use, there is hot exhaust gas flow though the catalyst cell and temperature of the cell is approximately +900 degree(s)C. Therefore non-contact Laser- Doppler-Vibrometer was used to measure vibration velocity of the catalyst cell. The laser beam was directed towards the cell through pipe which was put through and welded to the casing of the catalyst. The outer end of the pipe was screw down with a tempered class to prevent exhaust gas flow from the pipe. The inner end of the pipe was open and few millimeters away from the measuring point. Catalyst was attached to the engine with two ways, rigidly close to the engine and flexible under the engine. The engine was running in test bench under controlled conditions. Vibration measurements were carried out during constant running speeds of the engine. Vibration signals were captured and analyzed with FFT-analyzer. Vibration of catalyst cell was strongest at running speed of 5000 rpm, from 10 to 20 g (1 g equals 9.81 ms-2), when catalyst was attached rigidly close to the engine. At running speed of 3000 rpm, vibration of catalyst cell was from 2 to 3 g in most cases, when catalyst was attached either rigidly or flexible to the engine. It is estimated that in real life, i.e. when catalyst is attached to car with same engine, vibration of catalyst cell at running speed of 5000 rpm is somewhere between 1 and 10 g. At running speed of 3000 rpm, which may be more often used when driving car (car speed approximately 100 kmh-1), vibration of catalyst cell is probably few g's.

Mathematical model of marine diesel engine simulator for a new methodology of self propulsion tests

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

Izzuddin, Nur; Sunarsih,; Priyanto, Agoes

As a vessel operates in the open seas, a marine diesel engine simulator whose engine rotation is controlled to transmit through propeller shaft is a new methodology for the self propulsion tests to track the fuel saving in a real time. Considering the circumstance, this paper presents the real time of marine diesel engine simulator system to track the real performance of a ship through a computer-simulated model. A mathematical model of marine diesel engine and the propeller are used in the simulation to estimate fuel rate, engine rotating speed, thrust and torque of the propeller thus achieve the targetmore » vessel’s speed. The input and output are a real time control system of fuel saving rate and propeller rotating speed representing the marine diesel engine characteristics. The self-propulsion tests in calm waters were conducted using a vessel model to validate the marine diesel engine simulator. The simulator then was used to evaluate the fuel saving by employing a new mathematical model of turbochargers for the marine diesel engine simulator. The control system developed will be beneficial for users as to analyze different condition of vessel’s speed to obtain better characteristics and hence optimize the fuel saving rate.« less

Circuit engineering principles for construction of bipolar large-scale integrated circuit storage devices and very large-scale main memory

NASA Astrophysics Data System (ADS)

Neklyudov, A. A.; Savenkov, V. N.; Sergeyez, A. G.

1984-06-01

Memories are improved by increasing speed or the memory volume on a single chip. The most effective means for increasing speeds in bipolar memories are current control circuits with the lowest extraction times for a specific power consumption (1/4 pJ/bit). The control current circuitry involves multistage current switches and circuits accelerating transient processes in storage elements and links. Circuit principles for the design of bipolar memories with maximum speeds for an assigned minimum of circuit topology are analyzed. Two main classes of storage with current control are considered: the ECL type and super-integrated injection type storage with data capacities of N = 1/4 and N 4/16, respectively. The circuits reduce logic voltage differentials and the volumes of lexical and discharge buses and control circuit buses. The limiting speed is determined by the antiinterference requirements of the memory in storage and extraction modes.

Automated manual transmission clutch controller

DOEpatents

Lawrie, Robert E.; Reed, Jr., Richard G.; Rausen, David J.

1999-11-30

A powertrain system for a hybrid vehicle. The hybrid vehicle includes a heat engine, such as a diesel engine, and an electric machine, which operates as both an electric motor and an alternator, to power the vehicle. The hybrid vehicle also includes a manual-style transmission configured to operate as an automatic transmission from the perspective of the driver. The engine and the electric machine drive an input shaft which in turn drives an output shaft of the transmission. In addition to driving the transmission, the electric machine regulates the speed of the input shaft in order to synchronize the input shaft during either an upshift or downshift of the transmission by either decreasing or increasing the speed of the input shaft. When decreasing the speed of the input shaft, the electric motor functions as an alternator to produce electrical energy which may be stored by a storage device. Operation of the transmission is controlled by a transmission controller which receives input signals and generates output signals to control shift and clutch motors to effect smooth launch, upshift shifts, and downshifts of the transmission, so that the transmission functions substantially as an automatic transmission from the perspective of the driver, while internally substantially functioning as a manual transmission.

Automated manual transmission shift sequence controller

DOEpatents

Lawrie, Robert E.; Reed, Richard G.; Rausen, David J.

2000-02-01

A powertrain system for a hybrid vehicle. The hybrid vehicle includes a heat engine, such as a diesel engine, and an electric machine, which operates as both, an electric motor and an alternator, to power the vehicle. The hybrid vehicle also includes a manual-style transmission configured to operate as an automatic transmission from the perspective of the driver. The engine and the electric machine drive an input shaft which in turn drives an output shaft of the transmission. In addition to driving the transmission, the electric machine regulates the speed of the input shaft in order to synchronize the input shaft during either an upshift or downshift of the transmission by either decreasing or increasing the speed of the input shaft. When decreasing the speed of the input shaft, the electric motor functions as an alternator to produce electrical energy which may be stored by a storage device. Operation of the transmission is controlled by a transmission controller which receives input signals and generates output signals to control shift and clutch motors to effect smooth launch, upshift shifts, and downshifts of the transmission, so that the transmission functions substantially as an automatic transmission from the perspective of the driver, while internally substantially functioning as a manual transmission.

Automated manual transmission mode selection controller

DOEpatents

Lawrie, Robert E.

1999-11-09

A powertrain system for a hybrid vehicle. The hybrid vehicle includes a heat engine, such as a diesel engine, and an electric machine, which operates as both an electric motor and an alternator, to power the vehicle. The hybrid vehicle also includes a manual-style transmission configured to operate as an automatic transmission from the perspective of the driver. The engine and the electric machine drive an input shaft which in turn drives an output shaft of the transmission. In addition to driving the transmission, the electric machine regulates the speed of the input shaft in order to synchronize the input shaft during either an upshift or downshift of the transmission by either decreasing or increasing the speed of the input shaft. When decreasing the speed of the input shaft, the electric motor functions as an alternator to produce electrical energy which may be stored by a storage device. Operation of the transmission is controlled by a transmission controller which receives input signals and generates output signals to control shift and clutch motors to effect smooth launch, upshift shifts, and downshifts of the transmission, so that the transmission functions substantially as an automatic transmission from the perspective of the driver, while internally substantially functioning as a manual transmission.

Automated manual transmission controller

DOEpatents

Lawrie, Robert E.; Reed, Jr., Richard G.; Bernier, David R.

1999-12-28

A powertrain system for a hybrid vehicle. The hybrid vehicle includes a heat engine, such as a diesel engine, and an electric machine, which operates as both an electric motor and an alternator, to power the vehicle. The hybrid vehicle also includes a manual-style transmission configured to operate as an automatic transmission from the perspective of the driver. The engine and the electric machine drive an input shaft which in turn drives an output shaft of the transmission. In addition to driving the transmission, the electric machine regulates the speed of the input shaft in order to synchronize the input shaft during either an upshift or downshift of the transmission by either decreasing or increasing the speed of the input shaft. When decreasing the speed of the input shaft, the electric motor functions as an alternator to produce electrical energy which may be stored by a storage device. Operation of the transmission is controlled by a transmission controller which receives input signals and generates output signals to control shift and clutch motors to effect smooth launch, upshift shifts, and downshifts of the transmission, so that the transmission functions substantially as an automatic transmission from the perspective of the driver, while internally substantially functioning as a manual transmission.

Effects of Fuel Temperature on Injection Process and Combustion of Dimethyl Ether Engine.

PubMed

Guangxin, Gao; Zhulin, Yuan; Apeng, Zhou; Shenghua, Liu; Yanju, Wei

2013-12-01

To investigate the effects of fuel temperature on the injection process in the fuel-injection pipe and the combustion characteristics of compression ignition (CI) engine, tests on a four stroke, direct injection dimethyl ether (DME) engine were conducted. Experimental results show that as the fuel temperature increases from 20 to 40 °C, the sound speed is decreased by 12.2%, the peak line pressure at pump and nozzle sides are decreased by 7.2% and 5.6%, respectively. Meanwhile, the injection timing is retarded by 2.2 °CA and the injection duration is extended by 0.8 °CA. Accordingly, the ignition delay and the combustion duration are extended by 0.7 °CA and 4.0 °CA, respectively. The cylinder peak pressure is decreased by 5.4%. As a result, the effective thermal efficiency is decreased, especially for temperature above 40 °C. Before beginning an experiment, the fuel properties of DME, including the density, the bulk modulus, and the sound speed were calculated by "ThermoData." The calculated result of sound speed is consistent with the experimental results.

Effect of heat treatments on machinability of gold alloy with age-hardenability at intraoral temperature.

PubMed

Watanabe, I; Baba, N; Watanabe, E; Atsuta, M; Okabe, T

2004-01-01

This study investigated the effect of heat treatment on the machinability of heat-treated cast gold alloy with age-hardenability at intraoral temperature using a handpiece engine with SiC wheels and an air-turbine handpiece with carbide burs and diamond points. Cast gold alloy specimens underwent various heat treatments [As-cast (AC); Solution treatment (ST); High-temperature aging (HA), Intraoral aging (IA)] before machinability testing. The machinability test was conducted at a constant machining force of 0.784N. The three circumferential speeds used for the handpiece engine were 500, 1,000 and 1,500 m/min. The machinability index (M-index) was determined as the amount of metal removed by machining (volume loss, mm(3)). The results were analyzed by ANOVA and Scheffé's test. When an air-turbine handpiece was used, there was no difference in the M-index of the gold alloy among the heat treatments. The air-turbine carbide burs showed significantly (p<0.05) higher M-indexes than the diamond points after any heat treatments. With the SiC wheels, increasing the circumferential speed increased the M-index values for each heat treatment. The specimens heat-treated with AC, HA and IA had similar M-indexes at the lower speeds (500 and 1,000 m/min). The ST specimens exhibited the lowest M-index at the lower speeds. However, at the highest speed (1,500 m/min), there were no significant differences in the M-indexes among the heat treatments except for HA, which showed the highest M-index. There was no effect of heat treatment on the machinability of the gold alloy using the air-turbine handpiece. The heat treatments had a small effect on the M-index of the gold alloy machined with a SiC wheel for a handpiece engine.

Method and apparatus for controlling the solenoid current of a solenoid valve which controls the amount of suction of air in an internal combustion engine

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

Kiuchi, T.; Sakurai, H.

1988-09-20

This patent describes an apparatus for controlling the solenoid current of a solenoid valve which controls suction air in an internal combustion engine. The apparatus consists of: (a) engine rotational speed detector means for detecting engine rotational speed; (b) aimed idle speed setting means for generating a signal corresponding to a predetermined idling speed; (c) first calculating means coupled to the engine rotational speed detector means and the aimed idle speed setting means for calculating a feedback control term (Ifb(n)) as a function of an integration term (Iai), a proportion term (Ip), and a differentiation term (Id); (d) first determiningmore » and storing means coupled to the first calculating means, for determining an integration term (Iai(n)) of the the feedback control term (Ifb(n)) and for determining a determined value (Ixref) in accordance therewith; (e) changeover means coupled to the first calculating means and the first determining and storing means for selecting the output of one of the first calculating means or the first determining and storing means; (f) first signal generating means coupled to the changeover means for generating a solenoid current control value (Icmd) as a function of the output of the changeover means.« less

Method and apparatus for controlling the solenoid current of a solenoid valve which controls the amount of suction of air in an internal combustion engine

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

Kiuchi, T.; Yasuoka, A.

1988-09-13

This patent describes apparatus for controlling the solenoid current of a selenoid valve which controls the amount of suction air in an internal combustion engine, the apparatus comprising: (a) engine rotational speed detector means for detecting engine rotational speed; (b) aimed idle speed setting means for generating a signal corresponding to a predetermined idling speed; (c) first calculating means coupled to the engine rotational speed detector means and the aimed idle speed setting means for calculating a feedback control term Ifb(n) as a function of an integration term (Iai), a proportion term (Ip), and a differentiation term (Id); (d) firstmore » determining and storing means coupled to the first calculating means, for determining an integration term (Iai(n)) of the feedback control term (Ifb(n)) and for determining a determined value (Ixref) in accordance therewith; (e) changeover means coupled to the first calculating means and the first determining and storing means for selecting the output of one of the first calculating means or the first determining and storing means; (f) first signal generating means coupled to the changeover means for generating a solenoid current control value (Icmd) as a function of the output of the changeover.« less

Super Turbocharging the Direct Injection Diesel engine

NASA Astrophysics Data System (ADS)

Boretti, Albert

2018-03-01

The steady operation of a turbocharged diesel direct injection (TDI) engine featuring a variable speed ratio mechanism linking the turbocharger shaft to the crankshaft is modelled in the present study. Key parameters of the variable speed ratio mechanism are range of speed ratios, efficiency and inertia, in addition to the ability to control relative speed and flow of power. The device receives energy from, or delivers energy to, the crankshaft or the turbocharger. In addition to the pistons of the internal combustion engine (ICE), also the turbocharger thus contributes to the total mechanical power output of the engine. The energy supply from the crankshaft is mostly needed during sharp accelerations to avoid turbo-lag, and to boost torque at low speeds. At low speeds, the maximum torque is drastically improved, radically expanding the load range. Additionally, moving closer to the points of operation of a balanced turbocharger, it is also possible to improve both the efficiency η, defined as the ratio of the piston crankshaft power to the fuel flow power, and the total efficiency η*, defined as the ratio of piston crankshaft power augmented of the power from the turbocharger shaft to the fuel flow power, even if of a minimal extent. The energy supply to the crankshaft is possible mostly at high speeds and high loads, where otherwise the turbine could have been waste gated, and during decelerations. The use of the energy at the turbine otherwise waste gated translates in improvements of the total fuel conversion efficiency η* more than the efficiency η. Much smaller improvements are obtained for the maximum torque, yet again moving closer to the points of operation of a balanced turbocharger. Adopting a much larger turbocharger (target displacement x speed 30% larger than a conventional turbocharger), better torque outputs and fuel conversion efficiencies η* and η are possible at every speed vs. the engine with a smaller, balanced turbocharger. This result motivates further studies of the mechanism that may considerably benefit traditional powertrains based on diesel engines.

Aircraft dual-shaft jet engine with indirect action fuel flow controller

NASA Astrophysics Data System (ADS)

Tudosie, Alexandru-Nicolae

2017-06-01

The paper deals with an aircraft single-jet engine's control system, based on a fuel flow controller. Considering the engine as controlled object and its thrust the most important operation effect, from the multitude of engine's parameters only its rotational speed n is measurable and proportional to its thrust, so engine's speed has become the most important controlled parameter. Engine's control system is based on fuel injection Qi dosage, while the output is engine's speed n. Based on embedded system's main parts' mathematical models, the author has described the system by its block diagram with transfer functions; furthermore, some Simulink-Matlab simulations are performed, concerning embedded system quality (its output parameters time behavior) and, meanwhile, some conclusions concerning engine's parameters mutual influences are revealed. Quantitative determinations are based on author's previous research results and contributions, as well as on existing models (taken from technical literature). The method can be extended for any multi-spool engine, single- or twin-jet.

A Retro-Fit Control Architecture to Maintain Engine Performance With Usage

NASA Technical Reports Server (NTRS)

Litt, Jonathan S.; Sowers, T. Shane; Garg, Sanjay

2007-01-01

An outer loop retrofit engine control architecture is presented which modifies fan speed command to obtain a desired thrust based on throttle position. This maintains the throttle-to-thrust relationship in the presence of engine degradation, which has the effect of changing the engine s thrust output for a given fan speed. Such an approach can minimize thrust asymmetry in multi-engine aircraft, and reduce pilot workload. The outer loop control is demonstrated under various levels of engine deterioration using a standard deterioration profile as well as an atypical profile. It is evaluated across various transients covering a wide operating range. The modified fan speed command still utilizes the standard engine control logic so all original life and operability limits remain in place. In all cases it is shown that with the outer loop thrust control in place, the deteriorated engine is able to match the thrust performance of a new engine up to the limits the controller will allow.

Feasibility study for convertible engine torque converter

NASA Technical Reports Server (NTRS)

1985-01-01

The feasibility study has shown that a dump/fill type torque converter has excellent potential for the convertible fan/shaft engine. The torque converter space requirement permits internal housing within the normal flow path of a turbofan engine at acceptable engine weight. The unit permits operating the engine in the turboshaft mode by decoupling the fan. To convert to turbofan mode, the torque converter overdrive capability bring the fan speed up to the power turbine speed to permit engagement of a mechanical lockup device when the shaft speed are synchronized. The conversion to turbofan mode can be made without drop of power turbine speed in less than 10 sec. Total thrust delivered to the aircraft by the proprotor, fan, and engine during tansient can be controlled to prevent loss of air speed or altitude. Heat rejection to the oil is low, and additional oil cooling capacity is not required. The turbofan engine aerodynamic design is basically uncompromised by convertibility and allows proper fan design for quiet and efficient cruise operation. Although the results of the feasibility study are exceedingly encouraging, it must be noted that they are based on extrapolation of limited existing data on torque converters. A component test program with three trial torque converter designs and concurrent computer modeling for fluid flow, stress, and dynamics, updated with test results from each unit, is recommended.

Experimental Comparison of Speed : Fuel-flow and Speed-area Controls on a Turbojet Engine for Small Step Disturbances

NASA Technical Reports Server (NTRS)

Wenzel, L M; Hart, C E; Craig, R T

1957-01-01

Optimum proportional-plus-integral control settings for speed - fuel-flow control, determined by minimization of integral criteria, correlated well with analytically predicted optimum settings. Engine response data are given for a range of control settings around the optimum. An inherent nonlinearity in the speed-area loop necessitated the use of nonlinear controls. Response data for two such nonlinear control schemes are presented.

Preliminary Assessment of Variable Speed Power Turbine Technology on Civil Tiltrotor Size and Performance

NASA Technical Reports Server (NTRS)

Snyder, Christopher A.; Acree, Cecil W., Jr.

2012-01-01

A Large Civil Tiltrotor (LCTR) conceptual design was developed as part of the NASA Heavy Lift Rotorcraft Systems Investigation in order to establish a consistent basis for evaluating the benefits of advanced technology for large tiltrotors. The concept has since evolved into the second-generation LCTR2, designed to carry 90 passengers for 1,000 nm at 300 knots, with vertical takeoff and landing capability. This paper performs a preliminary assessment of variable-speed power turbine technology on LCTR2 sizing, while maintaining the same, advanced technology engine core. Six concepts were studied; an advanced, single-speed engine with a conventional power turbine layout (Advanced Conventional Engine, or ACE) using a multi-speed (shifting) gearbox. There were five variable-speed power turbine (VSPT) engine concepts, comprising a matrix of either three or four turbine stages, and fixed or variable guide vanes; plus a minimum weight, twostage, fixed-geometry VSPT. The ACE is the lightest engine, but requires a multi-speed (shifting) gearbox to maximize its fuel efficiency, whereas the VSPT concepts use a lighter, fixed-ratio gearbox. The NASA Design and Analysis of Rotorcraft (NDARC) design code was used to study the trades between rotor and engine efficiency and weight. Rotor performance was determined by Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics (CAMRAD II), and engine performance was estimated with the Numerical Propulsion System Simulation (NPSS). Design trades for the ACE vs. VSPT are presented in terms of vehicle gross and empty weight, propulsion system weight and mission fuel burn for the civil mission. Because of its strong effect on gearbox weight and on both rotor and engine efficiency, rotor speed was chosen as the reference design variable for comparing design trades. Major study assumptions are presented and discussed. Impressive engine power-to-weight and fuel efficiency reduced vehicle sensitivity to propulsion system choice. The 10% weight penalty for multi-speed gearbox was more significant than most engine technology weight penalties to the vehicle design because drive system weight is more than two times engine weight. Based on study assumptions, fixed-geometry VSPT concept options performed better than their variable-geometry counterparts. Optimum design gross weights varied 1% or less and empty weights less than 2% among the concepts studied, while optimum fuel burns varied up to 5%. The outcome for some optimum configurations was so unexpected as to recommend a deeper look at the underlying technology assumptions.

Improvement of Selected Logistics Processes Using Quality Engineering Tools

NASA Astrophysics Data System (ADS)

Zasadzień, Michał; Žarnovský, Jozef

2018-03-01

Increase in the number of orders, the increasing quality requirements and the speed of order preparation require implementation of new solutions and improvement of logistics processes. Any disruption that occurs during execution of an order often leads to customer dissatisfaction, as well as loss of his/her confidence. The article presents a case study of the use of quality engineering methods and tools to improve the e-commerce logistic process. This made it possible to identify and prioritize key issues, identify their causes, and formulate improvement and prevention measures.

Effect of multiple engine placement on aeroelastic trim and stability of flying wing aircraft

NASA Astrophysics Data System (ADS)

Mardanpour, Pezhman; Richards, Phillip W.; Nabipour, Omid; Hodges, Dewey H.

2014-01-01

Effects of multiple engine placement on flutter characteristics of a backswept flying wing resembling the HORTEN IV are investigated using the code NATASHA (Nonlinear Aeroelastic Trim And Stability of HALE Aircraft). Four identical engines with defined mass, inertia, and angular momentum are placed in different locations along the span with different offsets from the elastic axis while fixing the location of the aircraft c.g. The aircraft experiences body freedom flutter along with non-oscillatory instabilities that originate from flight dynamics. Multiple engine placement increases flutter speed particularly when the engines are placed in the outboard portion of the wing (60-70% span), forward of the elastic axis, while the lift to drag ratio is affected negligibly. The behavior of the sub- and supercritical eigenvalues is studied for two cases of engine placement. NATASHA captures a hump body-freedom flutter with low frequency for the clean wing case, which disappears as the engines are placed on the wings. In neither case is there any apparent coalescence between the unstable modes. NATASHA captures other non-oscillatory unstable roots with very small amplitude, apparently originating with flight dynamics. For the clean-wing case, in the absence of aerodynamic and gravitational forces, the regions of minimum kinetic energy density for the first and third bending modes are located around 60% span. For the second mode, this kinetic energy density has local minima around the 20% and 80% span. The regions of minimum kinetic energy of these modes are in agreement with calculations that show a noticeable increase in flutter speed if engines are placed forward of the elastic axis at these regions.

Black carbon from ships: a review of the effects of ship speed, fuel quality and exhaust gas scrubbing

NASA Astrophysics Data System (ADS)

Lack, D. A.; Corbett, J. J.

2012-01-01

The International Maritime Organization (IMO) has moved to address the health and climate impact of the emissions from the combustion of low-quality residual fuels within the commercial shipping industry. Fuel sulfur content (FS) limits and an efficiency design index for future ships are examples of such IMO actions. The impacts of black carbon (BC) emissions from shipping are now under review by the IMO, with a particular focus on the potential impacts of future Arctic shipping. Recognizing that associating impacts with BC emissions requires both ambient and onboard observations, we provide recommendations for the measurement of BC. We also evaluate current insights regarding the effect of ship speed (engine load), fuel quality and exhaust gas scrubbing on BC emissions from ships. Observations demonstrate that BC emission factors (EFBC) increases 3 to 6 times at very low engine loads (<25% compared to EFBC at 85-100% load); absolute BC emissions (per nautical mile of travel) also increase up to 100% depending on engine load, even with reduced load fuel savings. If fleets were required to operate at lower maximum engine loads, presumably associated with reduced speeds, then engines could be re-tuned, which would reduce BC emissions. Ships operating in the Arctic are likely running at highly variable engine loads (25-100%) depending on ice conditions and ice breaking requirements. The ships operating at low load may be emitting up to 50% more BC than they would at their rated load. Such variable load conditions make it difficult to assess the likely emissions rate of BC. Current fuel sulfur regulations have the effect of reducing EFBC by an average of 30% and potentially up to 80% regardless of engine load; a removal rate similar to that of scrubbers. Uncertainties among current observations demonstrate there is a need for more information on (a) the impact of fuel quality on EFBC using robust measurement methods and (b) the efficacy of scrubbers for the removal of particulate matter by size and composition.

Black carbon from ships: a review of the effects of ship speed, fuel quality and exhaust gas scrubbing

NASA Astrophysics Data System (ADS)

Lack, D. A.; Corbett, J. J.

2012-05-01

The International Maritime Organization (IMO) has moved to address the health and climate impact of the emissions from the combustion of low-quality residual fuels within the commercial shipping industry. Fuel sulfur content (FS) limits and an efficiency design index for future ships are examples of such IMO actions. The impacts of black carbon (BC) emissions from shipping are now under review by the IMO, with a particular focus on the potential impacts of future Arctic shipping. Recognizing that associating impacts with BC emissions requires both ambient and onboard observations, we provide recommendations for the measurement of BC. We also evaluate current insights regarding the effect of ship speed (engine load), fuel quality and exhaust gas scrubbing on BC emissions from ships. Observations demonstrate that BC emission factors (EFBC) increases 3 to 6 times at very low engine loads (<25% compared to EFBC at 85-100% load); absolute BC emissions (per nautical mile of travel) also increase up to 100% depending on engine load, even with reduced load fuel savings. If fleets were required to operate at lower maximum engine loads, presumably associated with reduced speeds, then engines could be re-tuned, which would reduce BC emissions. Ships operating in the Arctic are likely running at highly variable engine loads (25-100%) depending on ice conditions and ice breaking requirements. The ships operating at low load may be emitting up to 50% more BC than they would at their rated load. Such variable load conditions make it difficult to assess the likely emissions rate of BC. Current fuel sulfur regulations have the effect of reducing EFBC by an average of 30% and potentially up to 80% regardless of engine load; a removal rate similar to that of scrubbers. Uncertainties among current observations demonstrate there is a need for more information on a) the impact of fuel quality on EFBC using robust measurement methods and b) the efficacy of scrubbers for the removal of particulate matter by size and composition.

Altitude Performance of Annular Combustor Type Turbojet Engine with JFC-2 Fuel /james W. Useller, James L. Harp, Jr. and Zelmar Barson

NASA Technical Reports Server (NTRS)

Useller, James W; Harp, James L JR; Barson, Zelmar

1952-01-01

An investigation was made comparing the performance of JFC-2 fuel and unleaded, clear gasoline in a 3000-pound-thrust turbojet engine. The JFC-2 fuel was a blend of percent diesel fuel and 25 percent aviation gasoline. Engine combustion efficiency was equal to that obtained with gasoline at rated engine speed and altitudes up to 35,000 feet, but at lower engine speeds or at higher altitudes the JFC-2 fuel gave lower combustion efficiency. No discernible difference was obtained in starting or low-speed combustiion blow-out characteristics of the two fuels. Turbine-discharge radial temperature profiles were nearly the same at altitudes up to 35,000 feet.

Some historical trends in the research and development of aircraft

NASA Technical Reports Server (NTRS)

Spearman, M. L.

1983-01-01

A survey of some trends in aircraft design was made in an effort to determine the relation between research, development, test, and evaluation (RDT and E) and aircraft mission capability, requirements, and objectives. Driving forces in the history of aircraft include the quest for speed which involved design concepts incorporating jet propulsion systems and low drag features. The study of high speed design concepts promoted new experimental and analytical research techniques. These research techniques, in turn, have lead to concepts offering new performance potential. Design trends were directed toward increased speed, efficiency, productivity, and safety. Generally speaking, the research and development effort has been evolutionary in nature and, with the exception of the transition to supersonic flight, little has occurred since the origin of flight that has drastically changed the basic design fundamentals of aircraft. However, this does not preclude the possibility of dramatic changes in the future since the products of research are frequently unpredictable. Advances should be expected and sought in improved aerodynamics (reduced drag, enhanced lift, flow field exploitation); propulsion (improved engine cycles, multimode engines, alternate fuels, alternate power sources); structures (new materials, manufacturing techniques); all with a view toward increased efficiency and utility.

40 CFR 91.305 - Dynamometer specifications and calibration accuracy.

Code of Federal Regulations, 2011 CFR

2011-07-01

... specifications. (1) The dynamometer test stand and other instruments for measurement of engine speed and torque... accuracy. (1) The dynamometer test stand and other instruments for measurement of engine torque and speed...

40 CFR 91.305 - Dynamometer specifications and calibration accuracy.

Code of Federal Regulations, 2014 CFR

2014-07-01

... specifications. (1) The dynamometer test stand and other instruments for measurement of engine speed and torque... accuracy. (1) The dynamometer test stand and other instruments for measurement of engine torque and speed...

40 CFR 91.305 - Dynamometer specifications and calibration accuracy.

Code of Federal Regulations, 2013 CFR

2013-07-01

... specifications. (1) The dynamometer test stand and other instruments for measurement of engine speed and torque... accuracy. (1) The dynamometer test stand and other instruments for measurement of engine torque and speed...

40 CFR 91.305 - Dynamometer specifications and calibration accuracy.

Code of Federal Regulations, 2010 CFR

2010-07-01

... specifications. (1) The dynamometer test stand and other instruments for measurement of engine speed and torque... accuracy. (1) The dynamometer test stand and other instruments for measurement of engine torque and speed...

40 CFR 91.305 - Dynamometer specifications and calibration accuracy.

Code of Federal Regulations, 2012 CFR

2012-07-01

... specifications. (1) The dynamometer test stand and other instruments for measurement of engine speed and torque... accuracy. (1) The dynamometer test stand and other instruments for measurement of engine torque and speed...

40 CFR 1039.505 - How do I test engines using steady-state duty cycles, including ramped-modal testing?

Code of Federal Regulations, 2013 CFR

2013-07-01

.... You may extend the sampling time to improve measurement accuracy of PM emissions, using good..., you may omit speed, torque, and power points from the duty-cycle regression statistics if the... mapped. (2) For variable-speed engines without low-speed governors, you may omit torque and power points...

40 CFR 1039.505 - How do I test engines using steady-state duty cycles, including ramped-modal testing?

Code of Federal Regulations, 2012 CFR

2012-07-01

.... You may extend the sampling time to improve measurement accuracy of PM emissions, using good..., you may omit speed, torque, and power points from the duty-cycle regression statistics if the... mapped. (2) For variable-speed engines without low-speed governors, you may omit torque and power points...

AUTOMOTIVE DIESEL MAINTENANCE 1. UNIT VI, MAINTAINING MECHANICAL GOVERNORS--DETROIT DIESEL ENGINES.

ERIC Educational Resources Information Center

Human Engineering Inst., Cleveland, OH.

THIS MODULE OF A 30-MODULE COURSE IS DESIGNED TO DEVELOP AN UNDERSTANDING OF THE OPERATION AND MAINTENANCE OF MECHANICAL GOVERNORS USED ON DIESEL ENGINES. TOPICS ARE (1) TYPES OF GOVERNORS AND ENGINE LOCATION, (2) GOVERNOR APPLICATIONS, (3) LIMITING SPEED MECHANICAL GOVERNOR, (4) VARIABLE SPEED MECHANICAL GOVERNOR, AND (5) CONSTANT SPEED…

Real-Time Aircraft Engine-Life Monitoring

NASA Technical Reports Server (NTRS)

Klein, Richard

2014-01-01

This project developed an inservice life-monitoring system capable of predicting the remaining component and system life of aircraft engines. The embedded system provides real-time, inflight monitoring of the engine's thrust, exhaust gas temperature, efficiency, and the speed and time of operation. Based upon this data, the life-estimation algorithm calculates the remaining life of the engine components and uses this data to predict the remaining life of the engine. The calculations are based on the statistical life distribution of the engine components and their relationship to load, speed, temperature, and time.

Heat engine generator control system

DOEpatents

Rajashekara, K.; Gorti, B.V.; McMullen, S.R.; Raibert, R.J.

1998-05-12

An electrical power generation system includes a heat engine having an output member operatively coupled to the rotor of a dynamoelectric machine. System output power is controlled by varying an electrical parameter of the dynamoelectric machine. A power request signal is related to an engine speed and the electrical parameter is varied in accordance with a speed control loop. Initially, the sense of change in the electrical parameter in response to a change in the power request signal is opposite that required to effectuate a steady state output power consistent with the power request signal. Thereafter, the electrical parameter is varied to converge the output member speed to the speed known to be associated with the desired electrical output power. 8 figs.

Heat engine generator control system

DOEpatents

Rajashekara, Kaushik; Gorti, Bhanuprasad Venkata; McMullen, Steven Robert; Raibert, Robert Joseph

1998-01-01

An electrical power generation system includes a heat engine having an output member operatively coupled to the rotor of a dynamoelectric machine. System output power is controlled by varying an electrical parameter of the dynamoelectric machine. A power request signal is related to an engine speed and the electrical parameter is varied in accordance with a speed control loop. Initially, the sense of change in the electrical parameter in response to a change in the power request signal is opposite that required to effectuate a steady state output power consistent with the power request signal. Thereafter, the electrical parameter is varied to converge the output member speed to the speed known to be associated with the desired electrical output power.

40 CFR 90.302 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... apply to this subpart. Intermediate speed means the engine speed which is 85 percent of the rated speed. Natural gas means a fuel whose primary constituent is methane. Rated speed means the speed at which the...

40 CFR 90.302 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... apply to this subpart. Intermediate speed means the engine speed which is 85 percent of the rated speed. Natural gas means a fuel whose primary constituent is methane. Rated speed means the speed at which the...

Preliminary study of Low-Cost Micro Gas Turbine

NASA Astrophysics Data System (ADS)

Fikri, M.; Ridzuan, M.; Salleh, Hamidon

2016-11-01

The electricity consumption nowadays has increased due to the increasing development of portable electronic devices. The development of low cost micro gas turbine engine, which is designed for the purposes of new electrical generation Micro turbines are a relatively new distributed generation technology being used for stationary energy generation applications. They are a type of combustion turbine that produces both heat and electricity on a relatively small scaled.. This research are focusing of developing a low-cost micro gas turbine engine based on automotive turbocharger and to evaluation the performance of the developed micro gas turbine. The test rig engine basically was constructed using a Nissan 45V3 automotive turbocharger, containing compressor and turbine assemblies on a common shaft. The operating performance of developed micro gas turbine was analyzed experimentally with the increment of 5000 RPM on the compressor speed. The speed of the compressor was limited at 70000 RPM and only 1000 degree Celsius at maximum were allowed to operate the system in order to avoid any failure on the turbocharger bearing and the other components. Performance parameters such as inlet temperature, compressor temperature, exhaust gas temperature, and fuel and air flow rates were measured. The data was collected electronically by 74972A data acquisition and evaluated manually by calculation. From the independent test shows the result of the system, The speed of the LP turbine can be reached up to 35000 RPM and produced 18.5kw of mechanical power.

Unsteady Probabilistic Analysis of a Gas Turbine System

NASA Technical Reports Server (NTRS)

Brown, Marilyn

2003-01-01

In this work, we have considered an annular cascade configuration subjected to unsteady inflow conditions. The unsteady response calculation has been implemented into the time marching CFD code, MSUTURBO. The computed steady state results for the pressure distribution demonstrated good agreement with experimental data. We have computed results for the amplitudes of the unsteady pressure over the blade surfaces. With the increase in gas turbine engine structural complexity and performance over the past 50 years, structural engineers have created an array of safety nets to ensure against component failures in turbine engines. In order to reduce what is now considered to be excessive conservatism and yet maintain the same adequate margins of safety, there is a pressing need to explore methods of incorporating probabilistic design procedures into engine development. Probabilistic methods combine and prioritize the statistical distributions of each design variable, generate an interactive distribution and offer the designer a quantified relationship between robustness, endurance and performance. The designer can therefore iterate between weight reduction, life increase, engine size reduction, speed increase etc.

Increasing Reliability of a Small 2-Stroke Internal Combustion Engine for Dynamically Changing Altitudes

DTIC Science & Technology

2012-03-01

63 Figure 20: New 3 inch stainless pipe used as an intake manifold...speed range of 1,000 RPM to 4,000 RPM. Six electric heaters with a total capacity of 900 W were used to heat the inlet air allowing a maximum...of the engine volume and had a gummy diaphragm attached to reduce pressure and flow pulsations to allow for more accurate air flow measurements

Report on Technology Horizons: A Vision for Air Force Science and Technology During 2010-2030. Volume 1

DTIC Science & Technology

2010-05-15

flow and decision processes across the air and space domains. It thus comprises traditional wired and fiber-optic computer networks based on...dual flow path design allow high volumetric efficiency, and high cruise speed provides significantly increased survivability. Vertical takeoff...emerging “third-stream engine architectures” can enable for constant mass flow engines that can provide further reductions in fuel consumption. A wide

HIDEC F-15 adaptive engine control system flight test results

NASA Technical Reports Server (NTRS)

Smolka, James W.

1987-01-01

NASA-Ames' Highly Integrated Digital Electronic Control (HIDEC) flight test program aims to develop fully integrated airframe, propulsion, and flight control systems. The HIDEC F-15 adaptive engine control system flight test program has demonstrated that significant performance improvements are obtainable through the retention of stall-free engine operation throughout the aircraft flight and maneuver envelopes. The greatest thrust increase was projected for the medium-to-high altitude flight regime at subsonic speed which is of such importance to air combat. Adaptive engine control systems such as the HIDEC F-15's can be used to upgrade the performance of existing aircraft without resort to expensive reengining programs.

The Effect of Valve Timing Upon the Performance of a Supercharged Engine at Altitude and an Unsupercharged Engine at Sea Level

NASA Technical Reports Server (NTRS)

Schey, Oscar W; Biermann, Arnold E

1932-01-01

This investigation was conducted to determine the comparative effects of valve timing on the performance of an unsupercharged engine at sea level and a supercharged engine at altitude. The tests were conducted on the NACA universal test engine. The timing of the four valve events was varied over a wide range; the engine speeds were varied between 1,050 and 1,500 r.p.m.; the compression ratios were varied between 4.35:1 and 7.35:1. The conditions of exhaust pressure and carburetor pressure of a supercharged engine were simulated for altitudes between 0 and 18,000 feet. The results show that optimum valve timing for a supercharged engine at an altitude of 18,000 feet differs slightly from that for an unsupercharged engine at sea level. A small increase in power is obtained by using the optimum timing for 18,000 feet for altitudes above 5,000 feet. The timing of the intake opening and exhaust closing becomes more critical as the compression ratio is increased.

Comprehensive Modeling and Analysis of Rotorcraft Variable Speed Propulsion System With Coupled Engine/Transmission/Rotor Dynamics

NASA Technical Reports Server (NTRS)

DeSmidt, Hans A.; Smith, Edward C.; Bill, Robert C.; Wang, Kon-Well

2013-01-01

This project develops comprehensive modeling and simulation tools for analysis of variable rotor speed helicopter propulsion system dynamics. The Comprehensive Variable-Speed Rotorcraft Propulsion Modeling (CVSRPM) tool developed in this research is used to investigate coupled rotor/engine/fuel control/gearbox/shaft/clutch/flight control system dynamic interactions for several variable rotor speed mission scenarios. In this investigation, a prototypical two-speed Dual-Clutch Transmission (DCT) is proposed and designed to achieve 50 percent rotor speed variation. The comprehensive modeling tool developed in this study is utilized to analyze the two-speed shift response of both a conventional single rotor helicopter and a tiltrotor drive system. In the tiltrotor system, both a Parallel Shift Control (PSC) strategy and a Sequential Shift Control (SSC) strategy for constant and variable forward speed mission profiles are analyzed. Under the PSC strategy, selecting clutch shift-rate results in a design tradeoff between transient engine surge margins and clutch frictional power dissipation. In the case of SSC, clutch power dissipation is drastically reduced in exchange for the necessity to disengage one engine at a time which requires a multi-DCT drive system topology. In addition to comprehensive simulations, several sections are dedicated to detailed analysis of driveline subsystem components under variable speed operation. In particular an aeroelastic simulation of a stiff in-plane rotor using nonlinear quasi-steady blade element theory was conducted to investigate variable speed rotor dynamics. It was found that 2/rev and 4/rev flap and lag vibrations were significant during resonance crossings with 4/rev lagwise loads being directly transferred into drive-system torque disturbances. To capture the clutch engagement dynamics, a nonlinear stick-slip clutch torque model is developed. Also, a transient gas-turbine engine model based on first principles mean-line compressor and turbine approximations is developed. Finally an analysis of high frequency gear dynamics including the effect of tooth mesh stiffness variation under variable speed operation is conducted including experimental validation. Through exploring the interactions between the various subsystems, this investigation provides important insights into the continuing development of variable-speed rotorcraft propulsion systems.

Influence of Alternative Engine Concepts on LCTR2 Sizing and Mission Profile

NASA Technical Reports Server (NTRS)

Acree, C. W., Jr.; Snyder, Christopher A.

2012-01-01

The Large Civil Tiltrotor (LCTR) was developed as part of the NASA Heavy Lift Rotorcraft Systems Investigation in order to establish a consistent basis for evaluating the benefits of advanced technology for large tiltrotors. The concept has since evolved into the second-generation LCTR2, designed to carry 90 passengers for 1,000 nm at 300 knots, with vertical takeoff and landing. This paper examines the impact of advanced propulsion system concepts on LCTR2 sizing. Two concepts were studied: an advanced, single-speed engine with a conventional power turbine layout (Advanced Conventional Engine, or ACE), and a variable-speed power turbine engine (VSPT). The ACE is the lighter engine, but requires a multi-speed (shifting) gearbox, whereas the VSPT uses a lighter, fixed-ratio gearbox. The NASA Design and Analysis of Rotorcraft (NDARC) design code was used to study the trades between rotor and engine efficiency and weight. Rotor performance was determined by Comprehensive Analytical Model of Rotorcraft Aerodynamics and Dynamics (CAMRAD II), and engine performance was estimated with the Numerical Propulsion System Simulation (NPSS). Design trades for the ACE vs. VSPT are presented in terms of vehicle weight empty for variations in mission altitude and range; the effect of different One Engine Inoperative (OEI) criteria are also examined. Because of its strong effect on gearbox weight and on both rotor and engine efficiency, rotor speed was chosen as the reference design variable for comparing design trades. The two propulsion concepts had nearly identical vehicle weights and mission fuel consumption, and their relative advantages varied little with cruise altitude, mission range, or OEI criteria; high cruise altitude and low cruise tip speed were beneficial for both concepts.

Supercruiser Arrow HS-8

NASA Technical Reports Server (NTRS)

Lord, Paul; Kao, Edward; Abobo, Joey B.; Collins, Todd A.; Ma, Leong; Murad, Adnan; Naran, Hitesh; Nguyen, Thuan P.; Nuon, Timithy I.; Thomas, Dimitri D.

1992-01-01

Technology in aeronautics has advanced dramatically since the last design of a production High Speed Civil Transport (HSCT) aircraft. Newly projected requirements call for a new High Speed Civil Transport aircraft with a range of approximately 550 nm and at least 275 passenger capacity. The aircraft must be affordable and marketable. The new HSCT must be able to sustain long-duration flights and to absorb the abuse of daily operation. The new aircraft must be safe and simple to fly and require a minimum amount of maintenance. This aircraft must meet FAA certification criteria of FAR Part 25 and environmental constraints. Several design configurations were examined and two designs were selected for further investigation. The first design employs the delta planform wings and conventional empennage layout. The other design uses a swing wing layout and conventional empennage. Other engineering challenges, including materials and propulsion are also discussed. At a cruise flight speed between Mach 2.2 and Mach 3.0, no current generation of materials can endure the thermal loading of supersonic flight and satisfy the stringent weight requirements. A new generation of lightweight composite materials must be developed for the HSCT. With the enforcement of stage 3 noise restrictions, these new engines must be able to propel the aircraft and satisfy the noise limit. The engine with the most promise is the variable cycle engine. At low subsonic speeds the engine operates like a turbofan engine, providing the most efficient performance. At higher speeds the variable cycle engine operates as a turbojet power plant. The two large engine manufacturers, General Electric and Pratt & Whitney in the United States, are combining forces to make the variable cycle engine a reality.

Constant speed control of four-stroke micro internal combustion swing engine

NASA Astrophysics Data System (ADS)

Gao, Dedong; Lei, Yong; Zhu, Honghai; Ni, Jun

2015-09-01

The increasing demands on safety, emission and fuel consumption require more accurate control models of micro internal combustion swing engine (MICSE). The objective of this paper is to investigate the constant speed control models of four-stroke MICSE. The operation principle of the four-stroke MICSE is presented based on the description of MICSE prototype. A two-level Petri net based hybrid model is proposed to model the four-stroke MICSE engine cycle. The Petri net subsystem at the upper level controls and synchronizes the four Petri net subsystems at the lower level. The continuous sub-models, including breathing dynamics of intake manifold, thermodynamics of the chamber and dynamics of the torque generation, are investigated and integrated with the discrete model in MATLAB Simulink. Through the comparison of experimental data and simulated DC voltage output, it is demonstrated that the hybrid model is valid for the four-stroke MICSE system. A nonlinear model is obtained from the cycle average data via the regression method, and it is linearized around a given nominal equilibrium point for the controller design. The feedback controller of the spark timing and valve duration timing is designed with a sequential loop closing design approach. The simulation of the sequential loop closure control design applied to the hybrid model is implemented in MATLAB. The simulation results show that the system is able to reach its desired operating point within 0.2 s, and the designed controller shows good MICSE engine performance with a constant speed. This paper presents the constant speed control models of four-stroke MICSE and carries out the simulation tests, the models and the simulation results can be used for further study on the precision control of four-stroke MICSE.

Speed limits set lower than engineering recommendations.

DOT National Transportation Integrated Search

2016-08-01

The purpose of this project is to provide the Montana Department of Transportation (MDT) with a better understanding of the : operational and safety impacts of setting posted speed limits below engineering recommended values. This practice has been :...

Flame Acceleration and Transition to Detonation in High Speed Turbulent Combustion

DTIC Science & Technology

2016-12-21

gas mixtures and sprays is dif- ficult to overestimate, as it is the main process in all internal-combustion engines used for propulsion and energy...generation. These include piston engines, gas turbines, various types of jet engines, and some rocket engines . On the other hand , preventing high...speed combustion is critical for the safety of any human activities that involve handling of po- t entially explosive gases or volatile liquids . Thus

Performance tests of a single-cylinder compression-ignition engine with a displacer piston

NASA Technical Reports Server (NTRS)

Moore, C S; Foster, H H

1935-01-01

Engine performance was investigated using a rectangular displacer on the piston crown to cause a forced air flow in a vertical-disk combustion chamber of a single-cylinder, 4-stroke-cycle compression-ignition engine. The optimum air-flow area was determined first with the area concentrated at one end of the displacer and then with the area equally divided between two passages, one at each end of the displacer. Best performance was obtained with the two-passage air flow arranged to give a calculated maximum air-flow speed of 8 times the linear crank-pin speed. With the same fuel-spray formation as used without the air flow, the maximum clear exhaust brake mean effective pressure at 1,500 r.p.m. was increased from 90 to 115 pounds per square inch and the corresponding fuel consumption reduced from 0.46 to 0.43 pound per brake horsepower-hour. At 1,200 r.p.m., a maximum clear exhaust brake mean effective pressure of 120 pounds per square inch was obtained at a fuel consumption of 0.42 pound per brake horsepower-hour. At higher specific fuel consumption the brake mean effective pressure was still increasing rapidly.

Preliminary Results of the Determination of Inlet-Pressure Distortion Effects on Compressor Stall and Altitude Operating Limits of the J57-P-1 Turbojet Engine

NASA Technical Reports Server (NTRS)

Wallner, L. E.; Lubick, R. J.; Chelko, L. J.

1955-01-01

During an investigation of the J57-P-1 turbojet engine in the Lewis altitude wind tunnel, effects of inlet-flow distortion on engine stall characteristics and operating limits were determined. In addition to a uniform inlet-flow profile, the inlet-pressure distortions imposed included two radial, two circumferential, and one combined radial-circumferential profile. Data were obtained over a range of compressor speeds at an altitude of 50,000 and a flight Mach number of 0.8; in addition, the high- and low-speed engine operating limits were investigated up to the maximum operable altitude. The effect of changing the compressor bleed position on the stall and operating limits was determined for one of the inlet distortions. The circumferential distortions lowered the compressor stall pressure ratios; this resulted in less fuel-flow margin between steady-state operation and compressor stall. Consequently, the altitude operating Limits with circumferential distortions were reduced compared with the uniform inlet profile. Radial inlet-pressure distortions increased the pressure ratio required for compressor stall over that obtained with uniform inlet flow; this resulted in higher altitude operating limits. Likewise, the stall-limit fuel flows required with the radial inlet-pressure distortions were considerably higher than those obtained with the uniform inlet-pressure profile. A combined radial-circumferential inlet distortion had effects on the engine similar to the circumferential distortion. Bleeding air between the two compressors eliminated the low-speed stall limit and thus permitted higher altitude operation than was possible without compressor bleed.

Non-intrusive speed sensor. [space shuttle main engine turbopumps

NASA Technical Reports Server (NTRS)

Maram, J.; Wyett, L.

1984-01-01

A computerized literature search was performed to identify candidate technologies for remote, non-intrusive speed sensing applications in Space Shuttle Main Engine (SSME) turbopumps. The three most promising technologies were subjected to experimental evaluation to quantify their performance characteristics under the harsh environmental requirements within the turbopumps. Although the infrared and microwave approaches demonstrated excellent cavitation immunity in laboratory tests, the variable-source magnetic speed sensor emerged as the most viable approach. Preliminary design of this speed sensor encountered no technical obstacles and resulted in viable and feasible speed nut, sensor housing, and sensor coil designs.

Foam-Metal Liner Attenuation of Low-Speed Fan Noise

NASA Technical Reports Server (NTRS)

Sutliff, Daniel L.; Jones, Michael G.

2008-01-01

A foam-metal liner for attenuation of fan noise was developed for and tested on a low speed fan. This type of liner represents a significant advance over traditional liners due to the possibility for placement in close proximity to the rotor. An advantage of placing treatment in this region is the modification of the acoustic near field, thereby inhibiting noise generation mechanisms. This can result in higher attenuation levels than can be achieved by liners located in the nacelle inlet. In addition, foam-metal liners could potentially replace the fan rub-strip and containment components, ultimately reducing engine components and thus weight, which can result in a systematic increase in noise reduction and engine performance. Foam-metal liners have the potential to reduce fan noise by 4 dB based on this study.

Engineering Data on Selected High Speed Passenger Trucks

DOT National Transportation Integrated Search

1978-07-01

The purpose of this project is to compile a list of high speed truck engineering parameters for characterization in dynamic performance modeling activities. Data tabulations are supplied for trucks from France, Germany, Italy, England, Japan, U.S.S.R...

A brief review on the recent advances in scramjet engine

NASA Astrophysics Data System (ADS)

Choubey, Gautam; Pandey, K. M.; Maji, Ambarish; Deshamukhya, Tuhin

2017-07-01

The scramjet engine is the most favourable air breathing propulsive system and suitable option for high-speed flight (Ma<4). Several scientists across the globe are continuously working on the advancement of the high-speed scramjet engine due to its implementation in the military missiles, low-cost access to space etc. The mixing phenomena associated with air and fuel is the salient feature for the effective combustion process and the fuel and air should be mixed adequately before entering into the combustor. But the key challenges associated with scramjet engine are the high speed of air inside the combustor and low residence time which actually deteriorate the combustion phenomena. That's why numerous computational, as well as experimental researches are being carried out by several researchers. The flow-field inside the scramjet engine is very complex. Hence an elaborated approach of the complicated combustion and mixing process inside the combustor is essential for the upgradation of the effective scramjet engine. This paper clearly signifies a brief review of the current development in scramjet engine.

Correction of Temperatures of Air-Cooled Engine Cylinders for Variation in Engine and Cooling Conditions

NASA Technical Reports Server (NTRS)

Schey, Oscar W; Pinkel, Benjamin; Ellerbrock, Herman H , Jr

1939-01-01

Factors are obtained from semiempirical equations for correcting engine-cylinder temperatures for variation in important engine and cooling conditions. The variation of engine temperatures with atmospheric temperature is treated in detail, and correction factors are obtained for various flight and test conditions, such as climb at constant indicated air speed, level flight, ground running, take-off, constant speed of cooling air, and constant mass flow of cooling air. Seven conventional air-cooled engine cylinders enclosed in jackets and cooled by a blower were tested to determine the effect of cooling-air temperature and carburetor-air temperature on cylinder temperatures. The cooling air temperature was varied from approximately 80 degrees F. to 230 degrees F. and the carburetor-air temperature from approximately 40 degrees F. to 160 degrees F. Tests were made over a large range of engine speeds, brake mean effective pressures, and pressure drops across the cylinder. The correction factors obtained experimentally are compared with those obtained from the semiempirical equations and a fair agreement is noted.

Dynamic control of a homogeneous charge compression ignition engine

DOEpatents

Duffy, Kevin P [Metamora, IL; Mehresh, Parag [Peoria, IL; Schuh, David [Peoria, IL; Kieser, Andrew J [Morton, IL; Hergart, Carl-Anders [Peoria, IL; Hardy, William L [Peoria, IL; Rodman, Anthony [Chillicothe, IL; Liechty, Michael P [Chillicothe, IL

2008-06-03

A homogenous charge compression ignition engine is operated by compressing a charge mixture of air, exhaust and fuel in a combustion chamber to an autoignition condition of the fuel. The engine may facilitate a transition from a first combination of speed and load to a second combination of speed and load by changing the charge mixture and compression ratio. This may be accomplished in a consecutive engine cycle by adjusting both a fuel injector control signal and a variable valve control signal away from a nominal variable valve control signal. Thereafter in one or more subsequent engine cycles, more sluggish adjustments are made to at least one of a geometric compression ratio control signal and an exhaust gas recirculation control signal to allow the variable valve control signal to be readjusted back toward its nominal variable valve control signal setting. By readjusting the variable valve control signal back toward its nominal setting, the engine will be ready for another transition to a new combination of engine speed and load.

Noise reduction experience at Hughes Helicopter, Inc.

NASA Astrophysics Data System (ADS)

Janakiram, D. S.

1982-07-01

Noise reduction is mostly limited to light helicopters whose noise signature is dominated by their tail rotors. It is primarily hardware oriented. Well known noise reduction techniques such as reduction of rotor speeds with an accompanying increase in solidity to maintain performance, engine noise reduction with the use of exhaust mufflers, and acoustic blanketing of transmission and engine compartment are used. The concept of blade phasing as a means of reducing tail rotor noise is also used. Engine noise (exhaust noise), power train noise and airframe noise becomes important at low rotor tip speeds and means must be found to reduce these noise sources if further noise reductions are desired. The use of a special test rig aids in isolating the various noise sources and arriving at the penalties (performance or payload) involved in quieting them. Significant noise reduction are achieved for the light helicopter with minimum performance or weight penalties because of the dominance of a single noise source (the tail rotor).

Noise reduction experience at Hughes Helicopter, Inc.

NASA Technical Reports Server (NTRS)

Janakiram, D. S.

1982-01-01

Noise reduction is mostly limited to light helicopters whose noise signature is dominated by their tail rotors. It is primarily hardware oriented. Well known noise reduction techniques such as reduction of rotor speeds with an accompanying increase in solidity to maintain performance, engine noise reduction with the use of exhaust mufflers, and acoustic blanketing of transmission and engine compartment are used. The concept of blade phasing as a means of reducing tail rotor noise is also used. Engine noise (exhaust noise), power train noise and airframe noise becomes important at low rotor tip speeds and means must be found to reduce these noise sources if further noise reductions are desired. The use of a special test rig aids in isolating the various noise sources and arriving at the penalties (performance or payload) involved in quieting them. Significant noise reduction are achieved for the light helicopter with minimum performance or weight penalties because of the dominance of a single noise source (the tail rotor).

Big-BOE: Fusing Spanish Official Gazette with Big Data Technology.

PubMed

Basanta-Val, Pablo; Sánchez-Fernández, Luis

2018-06-01

The proliferation of new data sources, stemmed from the adoption of open-data schemes, in combination with an increasing computing capacity causes the inception of new type of analytics that process Internet of things with low-cost engines to speed up data processing using parallel computing. In this context, the article presents an initiative, called BIG-Boletín Oficial del Estado (BOE), designed to process the Spanish official government gazette (BOE) with state-of-the-art processing engines, to reduce computation time and to offer additional speed up for big data analysts. The goal of including a big data infrastructure is to be able to process different BOE documents in parallel with specific analytics, to search for several issues in different documents. The application infrastructure processing engine is described from an architectural perspective and from performance, showing evidence on how this type of infrastructure improves the performance of different types of simple analytics as several machines cooperate.

Military Hybrid Vehicle Survey

DTIC Science & Technology

2011-08-03

III Composite 4.3% Integrated starter generator for engine shut down, regenerative braking and avoidance of inefficient engine operation [28]. FMTV...eliminating the inefficiencies associated with idling, vehicle braking and low engine speed part load efficiency, many improvements can be realized...literature. They can be divided into the following two categories : (1) Time dependent speed profiles, shown in Figure 4, usually defined by the federal

General Theory of the Steady Motion of an Airplane

NASA Technical Reports Server (NTRS)

De Bothezat, George

1921-01-01

The writer points out briefly the history of the method proposed for the study of steady motion of an airplane, which is different from other methods now used. M. Paul Painleve has shown how convenient the drag-lift curve was for the study of airplane steady motion. The author later added to the drift-lift curve the curve called the "speed curve" which permits a direct checking of the speed of the airplane under all flying conditions. But the speed curve was plotted in the same quadrant as the drag-lift curve. Later, with the progressive development of aeronautical science, and with the continually increasing knowledge concerning engines and propellers, the author was brought to add the three other quadrants to the original quadrant, and thus was obtained the steady motion chart which is described in detail in this report. This charts permits one to read directly for a given airplane its horizontal speed at any altitude, its rate of climb at any altitude, its apparent inclination to the horizon at any moment, its ceiling, its propeller thrust, revolutions, efficiency, and power absorbed, that is the complete set of quantities involved in the subject, and to follow the variations of all these quantities both for variable altitude and for variable throttle. The chart also permits one to follow the variation of all of the above in flight as a function of the lift coefficient and of the speed. The author also discusses the interaction of the airplane and propeller through the slipstream and the question of the properties of the engine-propeller system and its dependence upon the properties of the engine considered alone and of the propeller considered alone. There is also a discussion of a standard atmosphere.

Wide speed range turboshaft study

NASA Technical Reports Server (NTRS)

Dangelo, Martin

1995-01-01

NASA-Lewis and NASA-Ames have sponsored a series of studies over the last few years to identify key high speed rotorcraft propulsion and airframe technologies. NASA concluded from these studies that for near term aircraft with cruise speeds up to 450 kt, tilting rotor rotorcraft concepts are the most economical and technologically viable. The propulsion issues critical to tilting rotor rotorcraft are: (1) high speed cruise propulsion system efficiency and (2) adequate power to hover safely with one engine inoperative. High speed cruise propeller efficiency can be dramatically improved by reducing rotor speed, yet high rotor speed is critical for good hover performance. With a conventional turboshaft, this wide range of power turbine operating speeds would result in poor engine performance at one or more of these critical operating conditions. This study identifies several wide speed range turboshaft concepts, and analyzes their potential to improve performance at the diverse cruise and hover operating conditions. Many unique concepts were examined, and the selected concepts are simple, low cost, relatively low risk, and entirely contained within the power turbine. These power turbine concepts contain unique, incidence tolerant airfoil designs that allow the engine to cruise efficiently at 51 percent of the hover rotor speed. Overall propulsion system efficiency in cruise is improved as much as 14 percent, with similar improvements in engine weight and cost. The study is composed of a propulsion requirement survey, a concept screening study, a preliminary definition and evaluation of selected concepts, and identification of key technologies and development needs. In addition, a civil transport tilting rotor rotorcraft mission analysis was performed to show the benefit of these concepts versus a conventional turboshaft. Other potential applications for this technology are discussed.

High-speed schlieren imaging of rocket exhaust plumes

NASA Astrophysics Data System (ADS)

Coultas-McKenney, Caralyn; Winter, Kyle; Hargather, Michael

2016-11-01

Experiments are conducted to examine the exhaust of a variety of rocket engines. The rocket engines are mounted in a schlieren system to allow high-speed imaging of the engine exhaust during startup, steady state, and shutdown. A variety of rocket engines are explored including a research-scale liquid rocket engine, consumer/amateur solid rocket motors, and water bottle rockets. Comparisons of the exhaust characteristics, thrust and cost for this range of rockets is presented. The variety of nozzle designs, target functions, and propellant type provides unique variations in the schlieren imaging.

Stratified charge rotary aircraft engine technology enablement program

NASA Technical Reports Server (NTRS)

Badgley, P. R.; Irion, C. E.; Myers, D. M.

1985-01-01

The multifuel stratified charge rotary engine is discussed. A single rotor, 0.7L/40 cu in displacement, research rig engine was tested. The research rig engine was designed for operation at high speeds and pressures, combustion chamber peak pressure providing margin for speed and load excursions above the design requirement for a high is advanced aircraft engine. It is indicated that the single rotor research rig engine is capable of meeting the established design requirements of 120 kW, 8,000 RPM, 1,379 KPA BMEP. The research rig engine, when fully developed, will be a valuable tool for investigating, advanced and highly advanced technology components, and provide an understanding of the stratified charge rotary engine combustion process.

Autonomous grain combine control system

DOEpatents

Hoskinson, Reed L.; Kenney, Kevin L.; Lucas, James R.; Prickel, Marvin A.

2013-06-25

A system for controlling a grain combine having a rotor/cylinder, a sieve, a fan, a concave, a feeder, a header, an engine, and a control system. The feeder of the grain combine is engaged and the header is lowered. A separator loss target, engine load target, and a sieve loss target are selected. Grain is harvested with the lowered header passing the grain through the engaged feeder. Separator loss, sieve loss, engine load and ground speed of the grain combine are continuously monitored during the harvesting. If the monitored separator loss exceeds the selected separator loss target, the speed of the rotor/cylinder, the concave setting, the engine load target, or a combination thereof is adjusted. If the monitored sieve loss exceeds the selected sieve loss target, the speed of the fan, the size of the sieve openings, or the engine load target is adjusted.

Combustion Limits and Efficiency of Turbojet Engines

NASA Technical Reports Server (NTRS)

Barnett, H. C.; Jonash, E. R.

1956-01-01

Combustion must be maintained in the turbojet-engine combustor over a wide range of operating conditions resulting from variations in required engine thrust, flight altitude, and flight speed. Furthermore, combustion must be efficient in order to provide the maximum aircraft range. Thus, two major performance criteria of the turbojet-engine combustor are (1) operatable range, or combustion limits, and (2) combustion efficiency. Several fundamental requirements for efficient, high-speed combustion are evident from the discussions presented in chapters III to V. The fuel-air ratio and pressure in the burning zone must lie within specific limits of flammability (fig. 111-16(b)) in order to have the mixture ignite and burn satisfactorily. Increases in mixture temperature will favor the flammability characteristics (ch. III). A second requirement in maintaining a stable flame -is that low local flow velocities exist in the combustion zone (ch. VI). Finally, even with these requirements satisfied, a flame needs a certain minimum space in which to release a desired amount of heat, the necessary space increasing with a decrease in pressure (ref. 1). It is apparent, then, that combustor design and operation must provide for (1) proper control of vapor fuel-air ratios in the combustion zone at or near stoichiometric, (2) mixture pressures above the minimum flammability pressures, (3) low flow velocities in the combustion zone, and (4) adequate space for the flame.

Design and Test of Fan/Nacelle Models Quiet High-Speed Fan Design

NASA Technical Reports Server (NTRS)

Miller, Christopher J. (Technical Monitor); Repp, Russ; Gentile, David; Hanson, David; Chunduru, Srinivas

2003-01-01

The primary objective of the Quiet High-Speed Fan (QHSF) program was to develop an advanced high-speed fan design that will achieve a 6 dB reduction in overall fan noise over a baseline configuration while maintaining similar performance. The program applies and validates acoustic, aerodynamic, aeroelastic, and mechanical design tools developed by NASA, US industry, and academia. The successful fan design will be used in an AlliedSignal Engines (AE) advanced regional engine to be marketed in the year 2000 and beyond. This technology is needed to maintain US industry leadership in the regional turbofan engine market.

Synchronizing Photography For High-Speed-Engine Research

NASA Technical Reports Server (NTRS)

Chun, K. S.

1989-01-01

Light flashes when shaft reaches predetermined angle. Synchronization system facilitates visualization of flow in high-speed internal-combustion engines. Designed for cinematography and holographic interferometry, system synchronizes camera and light source with predetermined rotational angle of engine shaft. 10-bit resolution of absolute optical shaft encoder adapted, and 2 to tenth power combinations of 10-bit binary data computed to corresponding angle values. Pre-computed angle values programmed into EPROM's (erasable programmable read-only memories) to use as angle lookup table. Resolves shaft angle to within 0.35 degree at rotational speeds up to 73,240 revolutions per minute.

Concept Designed and Developed for Distortion- Tolerant, High-Stability Engine Control

NASA Technical Reports Server (NTRS)

1995-01-01

Engine Control Future aircraft turbine engines, both commercial and military, must be able to successfully accommodate expected increased levels of steady-state and dynamic engine-face distortion. Advanced tactical aircraft are likely to use thrust vectoring to enhance their maneuverability. As a result, the engines will see more extreme aircraft angles-of-attack and sideslip levels than are currently encountered with present-day aircraft. Also, the mixed-compression inlets needed for the High Speed Civil Transport will likely encounter disturbances similar to those seen by tactical aircraft, in addition to planar pulse, inlet buzz, and high distortion levels at low flight speed and off-design operation. The current approach of incorporating a sufficient component design stall margin to tolerate these increased levels of distortion would significantly reduce performance. The objective of the High Stability Engine Control (HISTEC) program is to design, develop, and flight demonstrate an advanced, high-stability, integrated engine-control system that uses measurement-based, real-time estimates of distortion to enhance engine stability. The resulting distortion-tolerant control reduces the required design stall margin, with a corresponding increase in performance and decrease in fuel burn. The HISTEC concept has been designed and developed, and the software implementing the concept has successfully accommodated time-varying distortion. The NASA Lewis Research Center is currently overseeing the development and validation of the hardware and software necessary to flight test the HISTEC concept. HISTEC is a contracted effort with Pratt & Whitney of West Palm Beach, Florida. The HISTEC approach includes two major systems: A Distortion Estimation System (DES) and Stability Management Control (SMC). DES is an aircraft-mounted, high-speed processor that estimates the amount and type of distortion present and its effect on the engine. It uses high-response pressure measurements at the engine face to calculate indicators of the type and extent of distortion in real time. From these indicators, DES determines the effects of distortion on the propulsion systems and the corresponding engine match point necessary to accommodate it. DES output consists of fan and compressor pressure ratio trim commands that are passed to the SMC. In addition, DES uses maneuver information, consisting of angle-of-attack and sideslip from the flight control, to anticipate high inlet distortion conditions. The SMC, which is contained in the engine-mounted, Improved Digital Electronic Engine Control (IDEEC), includes advanced control laws to directly control the fan and compressor transient operating line (pressure ratio). These advanced control laws, with a multivariable design, have the potential for higher bandwidth and the resulting more precise control of engine match. The ability to measure and assess the distortion effects in real time coupled with a high-response controller improves engine stability at high levels of distortion. The software algorithms implementing DES have been designed, developed, and demonstrated, and integration testing of the DES and SMC software has been completed. The results show that the HISTEC system will be able to sense inlet distortion, determine the effect on engine stability, and accommodate distortion by maintaining an adequate margin for engine surge. The Pratt &Whitney Comprehensive Engine Diagnostic Unit was chosen as the DES processor. An instrumented inlet case for sensing distortion was designed and fabricated. HISTEC is scheduled for flight test on the ACTIVE F-15 aircraft at the NASA Dryden Flight Research Center in Edwards, California, in late 1996.

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

Ghosh, B.B.

The object of the study reported in this paper was to investigate the possibility of using the blend of kerosene with petrol in a gasoline engines, without much losses in performance. The authors carried out experiments on a four-stroke cycle Briggs and Stratton S. I. Engine using five blends of kerosene with petrol at a compression ratios 5.3 and 7.47 to 1 with and without surge chambers, at a constant engine speed of 1500 rev/min with the following conclusions: 1. At part-load and the lower compression ratio the brake thermal efficiency is improved with percentage increase of kerosene but atmore » the higher compression ratio it is improved only upto 50% kerosene blend with petrol. 2. The knock-free maximum bhp is reduced with (a) the percentage increase of kerosene, (b) the increase of compression ratio. 3. Use of a surge chamber increase the knock-free maximum bhp, and reduces the brake thermal efficiency.« less

High Speed Balancing Applied to the T700 Engine

NASA Technical Reports Server (NTRS)

Walton, J.; Lee, C.; Martin, M.

1989-01-01

The work performed under Contracts NAS3-23929 and NAS3-24633 is presented. MTI evaluated the feasibility of high-speed balancing for both the T700 power turbine rotor and the compressor rotor. Modifications were designed for the existing Corpus Christi Army Depot (CCAD) T53/T55 high-speed balancing system for balancing T700 power turbine rotors. Tests conducted under these contracts included a high-speed balancing evaluation for T700 power turbines in the Army/NASA drivetrain facility at MTI. The high-speed balancing tests demonstrated the reduction of vibration amplitudes at operating speed for both low-speed balanced and non-low-speed balanced T700 power turbines. In addition, vibration data from acceptance tests of T53, T55, and T700 engines were analyzed and a vibration diagnostic procedure developed.

Piloted Simulation Study of the Effects of High-Lift Aerodynamics on the Takeoff Noise of a Representative High-Speed Civil Transport

NASA Technical Reports Server (NTRS)

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

1999-01-01

As part of an effort between NASA and private industry to reduce airport-community noise for high-speed civil transport (HSCT) concepts, a piloted simulation study was initiated for the purpose of predicting the noise reduction benefits that could result from improved low-speed high-lift aerodynamic performance for a typical HSCT configuration during takeoff and initial climb. Flight profile and engine information from the piloted simulation were coupled with the NASA Langley Aircraft Noise Prediction Program (ANOPP) to estimate jet engine noise and to propagate the resulting source noise to ground observer stations. A baseline aircraft configuration, which also incorporated different levels of projected improvements in low-speed high-lift aerodynamic performance, was simulated to investigate effects of increased lift and lift-to-drag ratio on takeoff noise levels. Simulated takeoff flights were performed with the pilots following a specified procedure in which either a single thrust cutback was performed at selected altitudes ranging from 400 to 2000 ft, or a multiple-cutback procedure was performed where thrust was reduced by a two-step process. Results show that improved low-speed high-lift aerodynamic performance provides at least a 4 to 6 dB reduction in effective perceived noise level at the FAA downrange flyover measurement station for either cutback procedure. However, improved low-speed high-lift aerodynamic performance reduced maximum sideline noise levels only when using the multiple-cutback procedures.

Ultrasound-modulated bubble propulsion of chemically powered microengines.

PubMed

Xu, Tailin; Soto, Fernando; Gao, Wei; Garcia-Gradilla, Victor; Li, Jinxing; Zhang, Xueji; Wang, Joseph

2014-06-18

The use of an ultrasound (US) field for rapid and reversible control of the movement of bubble-propelled chemically powered PEDOT/Ni/Pt microengines is demonstrated. Such operation reflects the US-induced disruption of normal bubble evolution and ejection, essential for efficient propulsion of catalytic microtubular engines. It offers precise speed control, with sharp increases and decreases of the speed at low and high US powers, respectively. A wide range of speeds can thus be generated by tuning the US power. Extremely fast changes in the motor speed (<0.1 s) and reproducible "On/Off" activations are observed, indicating distinct advantages compared to motion control methods based on other external stimuli. Such effective control of the propulsion of chemically powered microengines, including remarkable "braking" ability, holds considerable promise for diverse applications.

Multiroller Traction Drive Speed Reducer. Evaluation for Automotive Gas Turbine Engine

DTIC Science & Technology

1982-06-01

Speed is deLermined by a magnetic pickup on a toothed wheel . Gas turbine engine instrumunelLtiouu i -designed 1f0r measurement of specific fuel...buffer seal and the fluid--film bearing measured a maximum total runout of 0.038 mm (0.0015 in.) at low speed. At higher speeds, above 8000 rpm, the...maximum was 0.025 mm (0.001 in.) except near 10 000 rpm, where the oscilloscope indicated an excursion of 0.045 mm (0.0018 in.). This runout was within

Emission reduction from diesel engine using fumigation methanol and diesel oxidation catalyst.

PubMed

Zhang, Z H; Cheung, C S; Chan, T L; Yao, C D

2009-07-15

This study is aimed to investigate the combined application of fumigation methanol and a diesel oxidation catalyst for reducing emissions of an in-use diesel engine. Experiments were performed on a 4-cylinder naturally-aspirated direct-injection diesel engine operating at a constant speed of 1800 rev/min for five engine loads. The experimental results show that at low engine loads, the brake thermal efficiency decreases with increase in fumigation methanol; but at high loads, it slightly increases with increase in fumigation methanol. The fumigation method results in a significant increase in hydrocarbon (HC), carbon monoxide (CO), and nitrogen dioxide (NO(2)) emissions, but decrease in nitrogen oxides (NO(x)), smoke opacity and the particulate mass concentration. For the submicron particles, the total number of particles decreases. In all cases, there is little change in geometrical mean diameter of the particles. After catalytic conversion, the HC, CO, NO(2), particulate mass and particulate number concentrations were significantly reduced at medium to high engine loads; while the geometrical mean diameter of the particles becomes larger. Thus, the combined use of fumigation methanol and diesel oxidation catalyst leads to a reduction of HC, CO, NO(x), particulate mass and particulate number concentrations at medium to high engine loads.

78 FR 65161 - Airworthiness Directives; Agusta S.p.A. (Type Certificate Currently Held by AgustaWestland S.p.A...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-31

... engine speeds during steady-state operations. These actions are intended to alert pilots to avoid certain... alert pilots to avoid certain engine speeds during steady-state operations, prevent failure of the third...

Aircraft thrust control

NASA Technical Reports Server (NTRS)

Walker, Neil (Inventor); Day, Stanley G. (Inventor); Collopy, Paul D. (Inventor); Bennett, George W. (Inventor)

1988-01-01

An integrated control system for coaxial counterrotating aircraft propulsors driven by a common gas turbine engine. The system establishes an engine pressure ratio by control of fuel flow and uses the established pressure ratio to set propulsor speed. Propulsor speed is set by adjustment of blade pitch.

High-speed cell recognition algorithm for ultrafast flow cytometer imaging system.

PubMed

Zhao, Wanyue; Wang, Chao; Chen, Hongwei; Chen, Minghua; Yang, Sigang

2018-04-01

An optical time-stretch flow imaging system enables high-throughput examination of cells/particles with unprecedented high speed and resolution. A significant amount of raw image data is produced. A high-speed cell recognition algorithm is, therefore, highly demanded to analyze large amounts of data efficiently. A high-speed cell recognition algorithm consisting of two-stage cascaded detection and Gaussian mixture model (GMM) classification is proposed. The first stage of detection extracts cell regions. The second stage integrates distance transform and the watershed algorithm to separate clustered cells. Finally, the cells detected are classified by GMM. We compared the performance of our algorithm with support vector machine. Results show that our algorithm increases the running speed by over 150% without sacrificing the recognition accuracy. This algorithm provides a promising solution for high-throughput and automated cell imaging and classification in the ultrafast flow cytometer imaging platform. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

High-speed noncontacting instrumentation for jet engine testing

NASA Astrophysics Data System (ADS)

Scotto, M. J.; Eismeier, M. E.

1980-03-01

This paper discusses high-speed, noncontacting instrumentation systems for measuring the operating characteristics of jet engines. The discussion includes optical pyrometers for measuring blade surface temperatures, capacitance clearanceometers for measuring blade tip clearance and vibration, and optoelectronic systems for measuring blade flex and torsion. In addition, engine characteristics that mandate the use of such unique instrumentation are pointed out as well as the shortcomings of conventional noncontacting devices. Experimental data taken during engine testing are presented and recommendations for future development discussed.

Preliminary Results of an Altitude-Wind-Tunnel Investigation of a TG-100A Gas Turbine-Propeller Engine. 3; Pressure and Temperature Distributions

NASA Technical Reports Server (NTRS)

Geisenheyner, Robert M.; Berdysz, Joseph J.

1947-01-01

An altitude-wind-tunnel investigation of a TG-100A gas turbine-propeller engine was performed. Pressure and temperature data were obtained at altitudes from 5000 to 35000 feet, compressor inlet ram-pressure ratios from 1.00 to 1.17, and engine speeds from 800 to 13000 rpm. The effect of engine speed, shaft horsepower, and compressor-inlet ram-pressure ratio on pressure and temperature distribution at each measuring station are presented graphically.

The Fundamental Principles of High-speed Semi-diesel Engines. Part I: a General Discussion of the Subject of Fuel Injection in Diesel Engines and Detailed Descriptions of Many Types of Injection Nozzles

NASA Technical Reports Server (NTRS)

Buchner,

1926-01-01

Three questions relating to the technical progress in the utilization of heavy oils are discussed. The first question considers solid injection in high-speed automobile engines, the second concerns the development of the hot-bulb engine, and the third question relates to the need for a more thorough investigation of the processes on which the formatation of combustible, rapidly-burning mixtures depend.

Speed Variance and Its Influence on Accidents.

ERIC Educational Resources Information Center

Garber, Nicholas J.; Gadirau, Ravi

A study was conducted to investigate the traffic engineering factors that influence speed variance and to determine to what extent speed variance affects accident rates. Detailed analyses were carried out to relate speed variance with posted speed limit, design speeds, and other traffic variables. The major factor identified was the difference…

Analysis of Experimental Sea-level Transient Data and Analog Method of Obtaining Altitude Response for Turbine-propeller Engine with Relay-type Speed Control

NASA Technical Reports Server (NTRS)

Vasu, George; Pack, George J

1951-01-01

Correlation has been established between transient engine and control data obtained experimentally and data obtained by simulating the engine and control with an analog computer. This correlation was established at sea-level conditions for a turbine-propeller engine with a relay-type speed control. The behavior of the controlled engine at altitudes of 20,000 and 35,000 feet was determined with an analog computer using the altitude pressure and temperature generalization factors to calculate the new engine constants for these altitudes. Because the engine response varies considerably at altitude some type of compensation appears desirable and four methods of compensation are discussed.

An experimental study of gaseous exhaust emissions of diesel engine using blend of natural fatty acid methyl ester

NASA Astrophysics Data System (ADS)

Sudrajad, Agung; Ali, Ismail; Samo, Khalid; Faturachman, Danny

2012-09-01

Vegetable oil form in Natural Fatty Acid Methyl Ester (FAME) has their own advantages: first of all they are available everywhere in the world. Secondly, they are renewable as the vegetables which produce oil seeds can be planted year after year. Thirdly, they are friendly with our environment, as they seldom contain sulphur element in them. This makes vegetable fuel studies become current among the various popular investigations. This study is attempt to optimization of using blend FAME on diesel engine by experimental laboratory. The investigation experimental project is comparison between using blend FAME and base diesel fuel. The engine experiment is conducted with YANMAR TF120M single cylinder four stroke diesel engine set-up at variable engine speed with constant load. The data have been taken at each point of engine speed during the stabilized engine-operating regime. Measurement of emissions parameters at difference engine speed conditions have generally indicated lower in emission NOx, but slightly higher on CO2 emission. The result also shown that the blends FAME are good in fuel consumption and potentially good substitute fuels for diesel engine

Aircraft engine-mounted camera system for long wavelength infrared imaging of in-service thermal barrier coated turbine blades

NASA Astrophysics Data System (ADS)

Markham, James; Cosgrove, Joseph; Scire, James; Haldeman, Charles; Agoos, Ian

2014-12-01

This paper announces the implementation of a long wavelength infrared camera to obtain high-speed thermal images of an aircraft engine's in-service thermal barrier coated turbine blades. Long wavelength thermal images were captured of first-stage blades. The achieved temporal and spatial resolutions allowed for the identification of cooling-hole locations. The software and synchronization components of the system allowed for the selection of any blade on the turbine wheel, with tuning capability to image from leading edge to trailing edge. Its first application delivered calibrated thermal images as a function of turbine rotational speed at both steady state conditions and during engine transients. In advance of presenting these data for the purpose of understanding engine operation, this paper focuses on the components of the system, verification of high-speed synchronized operation, and the integration of the system with the commercial jet engine test bed.

Aircraft engine-mounted camera system for long wavelength infrared imaging of in-service thermal barrier coated turbine blades.

PubMed

Markham, James; Cosgrove, Joseph; Scire, James; Haldeman, Charles; Agoos, Ian

2014-12-01

This paper announces the implementation of a long wavelength infrared camera to obtain high-speed thermal images of an aircraft engine's in-service thermal barrier coated turbine blades. Long wavelength thermal images were captured of first-stage blades. The achieved temporal and spatial resolutions allowed for the identification of cooling-hole locations. The software and synchronization components of the system allowed for the selection of any blade on the turbine wheel, with tuning capability to image from leading edge to trailing edge. Its first application delivered calibrated thermal images as a function of turbine rotational speed at both steady state conditions and during engine transients. In advance of presenting these data for the purpose of understanding engine operation, this paper focuses on the components of the system, verification of high-speed synchronized operation, and the integration of the system with the commercial jet engine test bed.

The Charging Process in a High-speed, Single-cylinder, Four-stroke Engine

NASA Technical Reports Server (NTRS)

Reynolds, Blake; Schecter, Harry; Taylor, E S

1939-01-01

Experimental measurements and theoretical calculations were made on an aircraft-type, single cylinder engine, in order to determine the physical nature of the inlet process, especially at high piston speeds. The engine was run at speeds from 1,500 to 2,600 r.p.m. (mean piston speeds of 1,370 to 2,380 feet per minute). Measurements were made of the cylinder pressure during the inlet stroke and of the power output and volumetric efficiency. Measurements were also made, with the engine not running, to determine the resistance and mass of air in the inlet valve port at various crank angles. Results of analysis indicate that mass has an appreciable effect, but friction plays the major part in restricting flow. The observed fact that the volumetric efficiency is considerably less than 100 percent is attributed to thermal effects. An estimate was made of the magnitude of these effects in the present case, and their general nature is discussed.

A New Turbo-shaft Engine Control Law during Variable Rotor Speed Transient Process

NASA Astrophysics Data System (ADS)

Hua, Wei; Miao, Lizhen; Zhang, Haibo; Huang, Jinquan

2015-12-01

A closed-loop control law employing compressor guided vanes is firstly investigated to solve unacceptable fuel flow dynamic change in single fuel control for turbo-shaft engine here, especially for rotorcraft in variable rotor speed process. Based on an Augmented Linear Quadratic Regulator (ALQR) algorithm, a dual-input, single-output robust control scheme is proposed for a turbo-shaft engine, involving not only the closed loop adjustment of fuel flow but also that of compressor guided vanes. Furthermore, compared to single fuel control, some digital simulation cases using this new scheme about variable rotor speed have been implemented on the basis of an integrated system of helicopter and engine model. The results depict that the command tracking performance to the free turbine rotor speed can be asymptotically realized. Moreover, the fuel flow transient process has been significantly improved, and the fuel consumption has been dramatically cut down by more than 2% while keeping the helicopter level fight unchanged.

Bell P–63A King Cobra at the Aircraft Engine Research Laboratory

NASA Image and Video Library

1944-01-21

The Army Air Forces lent the National Advisory Committee for Aeronautics (NACA) Aircraft Engine Research Laboratory a Bell P–63A King Cobra in October 1943 to complement the lab's extensive efforts to improve the Allison V–1710 engine. The V–1710-powered P–63A was a single-seat fighter that could reach speeds of 410 miles per hour and an altitude of 43,000 feet. The fighter, first produced in 1942, was an improvement on Bell’s P–39, but persistent performance problems at high altitudes prevented its acceptance by the Air Corps. Instead many of the P–63s were transferred to the Soviet Union. Almost every test facility at the NACA’s engine lab was used to study the Allison V–1710 engine and its supercharger during World War II. Researchers were able to improve the efficiency, capacity and pressure ratio of the supercharger. They found that improved cooling significantly reduced engine knock in the fuel. Once the researchers were satisfied with their improvements, the new supercharger and cooling components were installed on the P–63A. The Flight Research Division first established the aircraft’s normal flight performance parameters such as speed at various altitudes, rate of climb, and peak altitude. Ensuing flights established the performance parameters of the new configuration in order to determine the improved performance. The program increased V–1710’s horsepower from 1650 to 2250.

The Use of Large Valve Overlap in Scavenging a Supercharged Spark-ignition Engine Using Fuel Injection

NASA Technical Reports Server (NTRS)

Schey, Oscar W; Young, Alfred W

1932-01-01

This investigation was conducted to determine the effect of more complete scavenging on the full throttle power and the fuel consumption of a four-stroke-cycle engine. The NACA single-cylinder universal test engine equipped with both a fuel-injection system and a carburetor was used. The engine was scavenged by using a large valve overlap and maintaining a pressure in the inlet manifold of 2 inches of mercury above atmospheric. The maximum valve overlap used was 112 degrees. Tests were conducted for a range of compression ratios from 5.5 to 8.5. Except for variable speed tests, all tests were conducted at an engine speed of 1,500 r.p.m. The results of the tests show that the clearance volume of an engine can be scavenged by using a large valve overlap and about 2 to 5 inches of mercury pressure difference between the inlet and exhaust valve. With a fuel-injection system when the clearance volume was scavenged, a b.m.e.p. of over 185 pounds per square inch and a fuel consumption of 9.45 pound per brake horsepower per hour were obtained with a 6.5 compression ratio. An increase of approximately 10 pounds per square inch b.m.e.p. was obtained with a fuel-injection system over that with a carburetor.

Investigation of acceleration characteristics of a single-spool turbojet engine

NASA Technical Reports Server (NTRS)

Oppenheimer, Frank L; Pack, George J

1953-01-01

Operation of a single-spool turbojet engine with constant exhaust-nozzle area was investigated at one flight condition. Data were obtained by subjecting the engine to approximate-step changes in fuel flow, and the information necessary to show the relations of acceleration to the sensed engine variables was obtained. These data show that maximum acceleration occurred prior to stall and surge. In the low end of the engine-speed range the margin was appreciable; in the high-speed end the margin was smaller but had not been completely defined by these data. Data involving acceleration as a function of speed, fuel flow, turbine-discharge temperature, compressor-discharge pressure, and thrust have been presented and an effort has been made to show how a basic control system could be improved by addition of an override in which the acceleration characteristic is used not only to prevent the engine from entering the surge region but also to obtain acceleration along the maximum acceleration line during throttle bursts.

Computational Challenges of Viscous Incompressible Flows

NASA Technical Reports Server (NTRS)

Kwak, Dochan; Kiris, Cetin; Kim, Chang Sung

2004-01-01

Over the past thirty years, numerical methods and simulation tools for incompressible flows have been advanced as a subset of the computational fluid dynamics (CFD) discipline. Although incompressible flows are encountered in many areas of engineering, simulation of compressible flow has been the major driver for developing computational algorithms and tools. This is probably due to the rather stringent requirements for predicting aerodynamic performance characteristics of flight vehicles, while flow devices involving low-speed or incompressible flow could be reasonably well designed without resorting to accurate numerical simulations. As flow devices are required to be more sophisticated and highly efficient CFD took become increasingly important in fluid engineering for incompressible and low-speed flow. This paper reviews some of the successes made possible by advances in computational technologies during the same period, and discusses some of the current challenges faced in computing incompressible flows.

Low-Speed Fan Noise Attenuation from a Foam-Metal Liner

NASA Technical Reports Server (NTRS)

Sutliff, Daniel L.; Jones, Michael G.

2011-01-01

A foam-metal liner for attenuation of fan noise was developed for and tested on a low-speed fan. This type of liner represents a significant advance over traditional liners, due to the possibility of placement in close proximity to the rotor. An advantage of placing treatment in this region is that the acoustic near field is modified, thereby inhibiting the noise-generation mechanism. This can result in higher attenuation levels than could be achieved by liners located in the nacelle inlet. In addition, foam-metal liners could potentially replace the fan rub strip and containment components, ultimately reducing engine components and thus weight, which can result in a systematic increase in noise reduction and engine performance. Foam-metal liners have the potential to reduce fan noise by 4 dB based on this study.

Fluctuating pressures on fan blades of a turbofan engine: Static and wind-tunnel investigations

NASA Technical Reports Server (NTRS)

Schoenster, J. A.

1982-01-01

To investigate the fan noise generated from turbofan engines, miniature pressure transducers were used to measure the fluctuating pressure on the fan blades of a JT15D engine. Tests were conducted with the engine operating on an outdoor test stand and in a wind tunnel. It was found that a potential flow interaction between the fan blades and six, large support struts in the bypass duct is a dominant noise source in the JT15D engine. Effects of varying fan speed and the forward speed on the blade pressure are also presented.

Detecting the crankshaft torsional vibration of diesel engines for combustion related diagnosis

NASA Astrophysics Data System (ADS)

Charles, P.; Sinha, Jyoti K.; Gu, F.; Lidstone, L.; Ball, A. D.

2009-04-01

Early fault detection and diagnosis for medium-speed diesel engines is important to ensure reliable operation throughout the course of their service. This work presents an investigation of the diesel engine combustion related fault detection capability of crankshaft torsional vibration. The encoder signal, often used for shaft speed measurement, has been used to construct the instantaneous angular speed (IAS) waveform, which actually represents the signature of the torsional vibration. Earlier studies have shown that the IAS signal and its fast Fourier transform (FFT) analysis are effective for monitoring engines with less than eight cylinders. The applicability to medium-speed engines, however, is strongly contested due to the high number of cylinders and large moment of inertia. Therefore the effectiveness of the FFT-based approach has further been enhanced by improving the signal processing to determine the IAS signal and subsequently tested on a 16-cylinder engine. In addition, a novel method of presentation, based on the polar coordinate system of the IAS signal, has also been introduced; to improve the discrimination features of the faults compared to the FFT-based approach of the IAS signal. The paper discusses two typical experimental studies on 16- and 20-cylinder engines, with and without faults, and the diagnosis results by the proposed polar presentation method. The results were also compared with the earlier FFT-based method of the IAS signal.

Systems Engineering Methodology for Fuel Efficiency and its Application to the TARDEC Fuel Efficient Demonstrator (FED) Program

DTIC Science & Technology

2010-08-19

highlight the benefits of regenerative braking . Parameters within the drive cycle may include vehicle speed, elevation/grade changes, road surface...assist to downsize the engine due to infinite maximum speed requirements • Drive cycle less suited to regenerative braking improvement compared to...will be cycle dependent. A high speed drive cycle may for example drive a focus on aerodynamic improvements, while high frequency of braking will

Performance of a Small Internal Combustion Engine Using N-Heptane and Iso-Octane

DTIC Science & Technology

2010-03-01

evaluate the ON effects on a FUJI BF34-EI, small 4-stroke spark ignition engine as preliminary steps to using a military grade JP-8 jet turbine fuel ...K) Pcrit (MPa) HHV (kJ/kg) LHV (kJ/kg) n-Heptane C7H16 100.20 371.60 537.70 2.62 48,456 44,926 i-Octane C8H18 114.22 398.40 567.50 2.40 48,275 44,791...meter the fuel . The carburetor is equipped with both a high speed and low speed fuel jet . It is unknown what engine speed it switches from one to

Model-based diagnosis of large diesel engines based on angular speed variations of the crankshaft

NASA Astrophysics Data System (ADS)

Desbazeille, M.; Randall, R. B.; Guillet, F.; El Badaoui, M.; Hoisnard, C.

2010-07-01

This work aims at monitoring large diesel engines by analyzing the crankshaft angular speed variations. It focuses on a powerful 20-cylinder diesel engine with crankshaft natural frequencies within the operating speed range. First, the angular speed variations are modeled at the crankshaft free end. This includes modeling both the crankshaft dynamical behavior and the excitation torques. As the engine is very large, the first crankshaft torsional modes are in the low frequency range. A model with the assumption of a flexible crankshaft is required. The excitation torques depend on the in-cylinder pressure curve. The latter is modeled with a phenomenological model. Mechanical and combustion parameters of the model are optimized with the help of actual data. Then, an automated diagnosis based on an artificially intelligent system is proposed. Neural networks are used for pattern recognition of the angular speed waveforms in normal and faulty conditions. Reference patterns required in the training phase are computed with the model, calibrated using a small number of actual measurements. Promising results are obtained. An experimental fuel leakage fault is successfully diagnosed, including detection and localization of the faulty cylinder, as well as the approximation of the fault severity.

Performance and Durability Assessment of Two Emission Control Technologies Installed on a Legacy High-Speed Marine Diesel Engine

DTIC Science & Technology

2015-11-05

program investigated cost- effective technologies to reduce emissions from legacy marine engines. High-speed, high-population engine models in both...respectively) were driven by health effects and environmental impacts. The U.S. Navy assessed its contribution to the domestic marine emission inventory...greatest potential. A laboratory developmental assessment was followed by a shipboard evaluation. Effective technology concepts applied to high

High load operation in a homogeneous charge compression ignition engine

DOEpatents

Duffy, Kevin P [Metamora, IL; Kieser, Andrew J [Morton, IL; Liechty, Michael P [Chillicothe, IL; Hardy, William L [Peoria, IL; Rodman, Anthony [Chillicothe, IL; Hergart, Carl-Anders [Peoria, IL

2008-12-23

A homogeneous charge compression ignition engine is set up by first identifying combinations of compression ratio and exhaust gas percentages for each speed and load across the engines operating range. These identified ratios and exhaust gas percentages can then be converted into geometric compression ratio controller settings and exhaust gas recirculation rate controller settings that are mapped against speed and load, and made available to the electronic

Study on the high speed scramjet characteristics at Mach 10 to 15 flight condition

NASA Astrophysics Data System (ADS)

Takahashi, M.; Itoh, K.; Tanno, H.; Komuro, T.; Sunami, T.; Sato, K.; Ueda, S.

A scramjet engine model, designed to establish steady and strong combustion at free-stream conditions corresponding to Mach 12 flight, was tested in a large free-piston driven shock tunnel. Combustion tests of a previous engine model showed that combustion heat release obtained in the combustor was not sufficient to maintain strong combustion. For a new scramjet engine model, the inlet compression ratio was increased to raise the static temperature and density of the flow at the combustor entrance. As a result of the aerodynamic design change, the pressure rise due to combustion increased and the duration of strong combustion conditions in the combustor was extended. A hyper-mixer injector designed to enhance mixing and combustion by introducing streamwise vortices was applied to the new engine model. The results showed that the hyper mixer injector was very effective in promoting combustion heat release and establishing steady and strong combustion in the combustor.

Acoustic and Emission Characteristics of Small, High-Speed Internal Combustion Engines

DOT National Transportation Integrated Search

1981-07-01

The intent of this study is to obtain information on small high-speed engines so that their effect on the urban environment may be assessed, and if necessary, programs devised to reduce the noise and other emissions from vehicles using these highly d...

14 CFR 27.1521 - Powerplant limitations.

Code of Federal Regulations, 2010 CFR

2010-01-01

...) The gas temperature limits for turbine engines over the range of operating and atmospheric conditions... rotational speed shown under the rotor speed requirements in § 27.1509(c); and (3) The gas temperature limits for turbine engines over the range of operating and atmospheric conditions for which certification is...

14 CFR 27.1521 - Powerplant limitations.

Code of Federal Regulations, 2013 CFR

2013-01-01

...) The gas temperature limits for turbine engines over the range of operating and atmospheric conditions... rotational speed shown under the rotor speed requirements in § 27.1509(c); and (3) The gas temperature limits for turbine engines over the range of operating and atmospheric conditions for which certification is...

14 CFR 27.1521 - Powerplant limitations.

Code of Federal Regulations, 2011 CFR

2011-01-01

...) The gas temperature limits for turbine engines over the range of operating and atmospheric conditions... rotational speed shown under the rotor speed requirements in § 27.1509(c); and (3) The gas temperature limits for turbine engines over the range of operating and atmospheric conditions for which certification is...

14 CFR 27.1521 - Powerplant limitations.

Code of Federal Regulations, 2012 CFR

2012-01-01

...) The gas temperature limits for turbine engines over the range of operating and atmospheric conditions... rotational speed shown under the rotor speed requirements in § 27.1509(c); and (3) The gas temperature limits for turbine engines over the range of operating and atmospheric conditions for which certification is...

14 CFR 27.1521 - Powerplant limitations.

Code of Federal Regulations, 2014 CFR

2014-01-01

...) The gas temperature limits for turbine engines over the range of operating and atmospheric conditions... rotational speed shown under the rotor speed requirements in § 27.1509(c); and (3) The gas temperature limits for turbine engines over the range of operating and atmospheric conditions for which certification is...

14 CFR 23.1563 - Airspeed placards.

Code of Federal Regulations, 2014 CFR

2014-01-01

... multiengine-powered airplanes of more than 6,000 pounds maximum weight, and turbine engine-powered airplanes, the maximum value of the minimum control speed, VMC (one-engine-inoperative) determined under § 23.149... control and the airspeed indicator has features such as low speed awareness that provide ample warning...

14 CFR 23.1563 - Airspeed placards.

Code of Federal Regulations, 2013 CFR

2013-01-01

... multiengine-powered airplanes of more than 6,000 pounds maximum weight, and turbine engine-powered airplanes, the maximum value of the minimum control speed, VMC (one-engine-inoperative) determined under § 23.149... control and the airspeed indicator has features such as low speed awareness that provide ample warning...

Altitude Wind Tunnel Control Room

NASA Image and Video Library

1945-05-21

Researchers at the National Advisory Committee for Aeronautics (NACA) Aircraft Engine Research Laboratory monitor a ramjet's performance in the Altitude Wind Tunnel from the control room. The soundproof control room was just a few feet from the tunnel’s 20-foot-diameter test section. In the control room, the operators could control all aspects of the tunnel’s operation, including the air density, temperature, and speed. They also operated the engine or test article in the test section by controlling the angle-of-attack, speed, power, and other parameters. The men in this photograph are monitoring the engine’s thrust and lift. A NACA-designed 20-inch-diameter ramjet was installed in the tunnel in May 1945. Thrust figures from these runs were compared with drag data from tests of scale models in small supersonic tunnels to verify the ramjet’s feasibility. The tunnel was used to analyze the ramjet’s overall performance up to altitudes of 47,000 feet and speeds to Mach 1.84. The researchers found that an increase in altitude caused a reduction in the engine’s horsepower and identified optimal flameholder configurations.

[Experimental study on characteristics of biodiesel exhausted particle].

PubMed

Ge, Yun-shan; He, Chao; Han, Xiu-kun; Wu, Si-jin; Lu, Xiao-ming

2007-07-01

A particle emission experiment of a direct-injection turbocharged diesel engine with biodiesel and diesel was carried out. A pump of 80 L/min and fiber glass filters with diameter of 90 mm was used to sample engine particles in exhaust pipe. The size distribution, soluble organic fraction (SOF) and 16 polycyclic aromatic hydrocarbons (PAHs) of particles were analyzed by a laser diffraction particle size analyzer and GC-MS. The results indicate that the volume weighted size distribution of biodiesel particle is single-peak and its median diameter d(0.5) and mean diameter d32 are decreased with the increasing speed. At the high speed the d32 and d(0.5) of biodiesel are larger than those of diesel, and quite the contrary at the low speed. SOF mass concentration and mass percentage of biodiesel are 12.3 - 31.5 mg/m3 and 38.2% - 58.0% respectively, which are much higher than those of diesel. The total PAHs emission concentration of biodiesel is 2.9 - 4.7 microg/m3 lower than that of diesel as much as 29.1% - 92.4%.

Acceleration of high-pressure-ratio single-spool turbojet engine as determined from component performance characteristics I : effect of air bleed at compressor outlet

NASA Technical Reports Server (NTRS)

Rebeske, John J , Jr; Rohlik, Harold E

1953-01-01

An analytical investigation was made to determine from component performance characteristics the effect of air bleed at the compressor outlet on the acceleration characteristics of a typical high-pressure-ratio single-spool turbojet engine. Consideration of several operating lines on the compressor performance map with two turbine-inlet temperatures showed that for a minimum acceleration time the turbine-inlet temperature should be the maximum allowable, and the operating line on the compressor map should be as close to the surge region as possible throughout the speed range. Operation along such a line would require a continuously varying bleed area. A relatively simple two-step area bleed gives only a small increase in acceleration time over a corresponding variable-area bleed. For the modes of operation considered, over 84 percent of the total acceleration time was required to accelerate through the low-speed range ; therefore, better low-speed compressor performance (higher pressure ratios and efficiencies) would give a significant reduction in acceleration time.

ARC-1961-A-28387

NASA Image and Video Library

1961-10-31

Lockheed NC-130B STOL turboprop-powered aircraft with ailerons drooped 30 degrees. Note trailing-edge flaps deflected 90 degrees for increased lift. Two T-56 turboshaft engines, which drove wing-mounted load compressors for boundary-layer control, are mounted on outboard wing pods. Landing approach speed was reduced 30 knots with boundary-layer control

Electro-Optical Approach for Airborne Marine Mammal Surveys and Density Estimations

DTIC Science & Technology

2011-10-01

the resolution needed for detecting animals as small as dolphins . Those two factors coupled with an increase in aircraft speed gives an order of...resulted in numerous patents in microwave and optical engineering with several dozen publications. He has led development of air to underwater Laser

Continued Investigation of Leakage and Power Loss Test Results for Competing Turbine Engine Seals

NASA Technical Reports Server (NTRS)

Delgado, Irebert R.; Proctor, Margaret P.

2007-01-01

Seal leakage decreases with increasing surface speed due to reduced clearances from disk centrifugal growth. Annular and labyrinth seal leakage are 2-3 times greater than brush and finger seal leakage. Seal leakage rates increase with increasing temperature because of seal clearance growth due to different coefficients of thermal expansion between the seal and test disk. Seal power loss is not strongly affected by inlet temperature. Seal power loss increases with increasing surface speed, seal pressure differential, mass flow rate or flow factor, and radial clearance. The brush and finger seals had nearly the same power loss. Annular and labyrinth seal power loss were higher than finger or brush seal power loss. The brush seal power loss was the lowest and 15-30% lower than annular and labyrinth seal power loss.

Research requirements for emergency power to permit hover-one-engine-inoperative helicopter operation

NASA Technical Reports Server (NTRS)

Yost, J. H.

1976-01-01

The research and technology demonstration requirements to achieve emergency-power capability for a civil helicopter are documented. The goal for emergency power is the ability to hover with one engine inoperative, transition to minimum-power forward flight, and continue to a safe landing where emergency power may or may not be required. The best method to obtain emergency power is to augment the basic engine power by increasing the engine's speed and turbine-inlet temperature, combined with water-alcohol injection at the engine inlet. Other methods, including turbine boost power and flywheel energy, offer potential for obtaining emergency power for minimum time durations. Costs and schedules are estimated for a research and development program to bring emergency power through a hardware-demonstration test. Interaction of engine emergency-power capability with other helicopter systems is examined.

Method of controlling a variable geometry type turbocharger

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

Hirabayashi, Y.

1988-08-23

This patent describes a method of controlling the supercharging pressure of a variable geometry type turbocharger having a bypass, comprising the following steps which are carried out successively: receiving signals from an engine speed sensor and from an engine knocking sensor; receiving a signal from a throttle valve sensor; judging whether or not an engine is being accelerated, and proceeding to step below if the engine is being accelerated and to step below if the engine is not being accelerated, i.e., if the engine is in a constant speed operation; determining a first correction value and proceeding to step below;more » judging whether or not the engine is knocking, and proceeding to step (d) if knocking is occurring and to step (f) below if no knocking is occurring; determining a second correction value and proceeding to step; receiving signals from the engine speed sensor and from an airflow meter which measures the quantity of airflow to be supplied to the engine; calculating an airflow rate per engine revolution; determining a duty valve according to the calculated airflow rate; transmitting the corrected duty value to control means for controlling the geometry of the variable geometry type turbocharger and the opening of bypass of the turbocharger, thereby controlling the supercharging pressure of the turbocharger.« less

High-speed spectral infrared imaging of spark ignition engine combustion. (Reannouncement with new availability information)

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

McComiskey, T.; Jiang, H.; Qian, Y.

1993-03-05

In-cylinder flame propagation and its impact on thermal characteristics of the combustion chamber were studied by using a new high-speed spectral infrared imaging system. In this work, successive spectral IR images of combustion chamber events were captured while varying several parameters, including fuel/air, spark timing, speed, and warming-up period. Some investigation of cyclic variation, knock, and high-temperature components during the non-combustion period was also conducted. It was found that the spectral images obtained in both short and long wavelength bands exhibited unique pieces of in-cylinder information, i.e., (qualitative) distributions of temperature and combustion products, respectively. During the combustion period, themore » temperature of early-formed combustion products continued to increase while the flame front temperature, e.g. near the end gas zone, remained relatively low. The exhaust valve emitted strong radiation starting from the early stage of the combustion period. The spark plug emitted the strongest radiation during the non-combustion period. Considerable cyclic variation in growth of the flame front and completion of the reaction was observable. The radiation from both spectral bands became stronger as the engine warm-up period in While operating the engine with the addition of n-heptane in the intake to produce knock, we captured spectral IR images of the end gas right before it was abruptly consumed. The combustion products that were formed in the end-gas volume upon knock, showed no evidence of higher temperature than other zones in the combustion chamber.... Spectral infrared imaging, High-speed, Digital data, Instantaneous distribution, Spark ignition combustion.« less

The scaling of performance and losses in miniature internal combustion engines

NASA Astrophysics Data System (ADS)

Menon, Shyam Kumar

Miniature glow ignition internal combustion (IC) piston engines are an off--the--shelf technology that could dramatically increase the endurance of miniature electric power supplies and the range and endurance of small unmanned air vehicles provided their overall thermodynamic efficiencies can be increased to 15% or better. This thesis presents the first comprehensive analysis of small (<500 g) piston engine performance. A unique dynamometer system is developed that is capable of making reliable measurements of engine performance and losses in these small engines. Methodologies are also developed for measuring volumetric, heat transfer, exhaust, mechanical, and combustion losses. These instruments and techniques are used to investigate the performance of seven single-cylinder, two-stroke, glow fueled engines ranging in size from 15 to 450 g (0.16 to 7.5 cm3 displacement). Scaling rules for power output, overall efficiency, and normalized power are developed from the data. These will be useful to developers of micro-air vehicles and miniature power systems. The data show that the minimum length scale of a thermodynamically viable piston engine based on present technology is approximately 3 mm. Incomplete combustion is the most important challenge as it accounts for 60-70% of total energy losses. Combustion losses are followed in order of importance by heat transfer, sensible enthalpy, and friction. A net heat release analysis based on in-cylinder pressure measurements suggest that a two--stage combustion process occurs at low engine speeds and equivalence ratios close to 1. Different theories based on burning mode and reaction kinetics are proposed to explain the observed results. High speed imaging of the combustion chamber suggests that a turbulent premixed flame with its origin in the vicinity of the glow plug is the primary driver of combustion. Placing miniature IC engines on a turbulent combustion regime diagram shows that they operate in the 'flamelet in eddy' regime whereas conventional--scale engines operate mostly in the 'wrinkled laminar flame sheet' regime. Taken together, the results show that the combustion process is the key obstacle to realizing the potential of small IC engines. Overcoming this obstacle will require new diagnostic techniques, measurements, combustion models, and high temperature materials.

High speed turning of compacted graphite iron using controlled modulation

NASA Astrophysics Data System (ADS)

Stalbaum, Tyler Paul

Compacted graphite iron (CGI) is a material which emerged as a candidate material to replace cast iron (CI) in the automotive industry for engine block castings. Its thermal and mechanical properties allow the CGI-based engines to operate at higher cylinder pressures and temperatures than CI-based engines, allowing for lower fuel emissions and increased fuel economy. However, these same properties together with the thermomechanical wear mode in the CGI-CBN system result in poor machinability and inhibit CGI from seeing wide spread use in the automotive industry. In industry, machining of CGI is done only at low speeds, less than V = 200 m/min, to avoid encountering rapid wear of the cutting tools during cutting. Studies have suggested intermittent cutting operations such as milling suffer less severe tool wear than continuous cutting. Furthermore, evidence that a hard sulfide layer which forms over the cutting edge in machining CI at high speeds is absent during machining CGI is a major factor in the difference in machinability of these material systems. The present study addresses both of these issues by modification to the conventional machining process to allow intermittent continuous cutting. The application of controlled modulation superimposed onto the cutting process -- modulation-assisted machining (MAM) -- is shown to be quite effective in reducing the wear of cubic boron nitride (CBN) tools when machining CGI at high machining speeds (> 500 m/min). The tool life is at least 20 times greater than found in conventional machining of CGI. This significant reduction in wear is a consequence of reduction in the severity of the tool-work contact conditions with MAM. The propensity for thermochemical wear of CBN is thus reduced. It is found that higher cutting speed (> 700 m/min) leads to lower tool wear with MAM. The MAM configuration employing feed-direction modulation appears feasible for implementation at high speeds and offers a solution to this challenging class of industrial machining applications. This study's approach is by series of high speed turning tests of CGI with CBN tools, comparing conventional machining to MAM for similar parameters otherwise, by tool wear measurements and machinability observations.

Advanced Gas Turbine (AGT) powertrain system development for automotive applications

NASA Technical Reports Server (NTRS)

1981-01-01

Preliminary layouts were made for the exhaust system, air induction system, and battery installation. Points of interference were identified and resolved by altering either the vehicle or engine designs. An engine general arrangement evolved to meet the vehicle engine compartment constraints while minimizing the duct pressure losses and the heat rejection. A power transfer system (between gasifier and power turbines) was developed to maintain nearly constant temperatures throughout the entire range of engine operation. An advanced four speed automatic transmission was selected to be used with the engine. Performance calculations show improvements in component efficiencies and an increase in fuel economy. A single stage centrifugal compressor design was completed and released for procurement. Gasifier turbine, power turbine, combustor, generator, secondary systems, materials, controls, and transmission development are reported.

Rotordynamic Design Analysis of an Oil-Free Turbocharger

NASA Technical Reports Server (NTRS)

Howard, Samuel A.

1997-01-01

Modern heavy duty diesel engines utilize turbochargers for increased power output. Also, a wide range of power levels can be achieved with one engine displacement through the use of different turbocharger configurations, eliminating the need for several different sized engines. These are the reasons that virtually all diesel truck engines currently marketed use turbochargers. However, because these turbochargers rely on ring seals and oil-lubricated floating sleeve bearings, they often suffer breakdowns. These turbochargers operate at elevated temperatures which often causes the oil to degrade and even coke to the bearing surfaces. This can lead to catastrophic failure, increased particulate emissions from oil leaks, and, in extreme cases, engine fires. Replacing the oil lubricated bearings from these turbochargers with some other device is desirable to eliminate these inherent problems. Foil bearings are compliant selecting bearings lubricated by air and are well suited to high speed, light load applications. Thus, foil bearings present one potential replacement for oil-lubricated sleeve bearings. Their use as such is investigated in this work.

CF6 jet engine performance improvement: New fan

NASA Technical Reports Server (NTRS)

Fasching, W. A.

1980-01-01

As part of the NASA sponsored engine component improvement program, and fan package was developed to reduce fuel consumption in current CF6 turbofan aircraft engine. The new fan package consist of an improved fan blade, reduced fan tip clearance due to a fan case stiffener, and a smooth fan casing tip shroud. CF6 engine performance and acoustic tests demonstrated the predicted 1.8% improvement in cruise sfc without an increase in engine noise. Power management thrust/fan speed characteristics were defined. Mechanical and structural integrity was demonstrated in model fan rotor photoelastic stress tests, full-size fan blade bench fatigue tests, and CF6 engine bird ingestion, crosswind, and cyclic endurance tests. The fan was certified in the CF6-500c2/E2 engines and is in commerical service on the Boeing 747-200, Douglas DC-10-30, and Atrbus industrie A300B aircraft.

Off-Design Performance of a Streamline-Traced, External-Compression Supersonic Inlet

NASA Technical Reports Server (NTRS)

Slater, John W.

2017-01-01

A computational study was performed to explore the aerodynamic performance of a streamline-traced, external-compression inlet designed for Mach 1.664 at off-design conditions of freestream Mach number, angle-of-attack, and angle-of-sideslip. Serious degradation of the inlet performance occurred for negative angles-of-attack and angles-of-sideslip greater than 3 degrees. At low subsonic speeds, the swept leading edges of the inlet created a pair of vortices that propagated to the engine face. Increasing the bluntness of the cowl lip showed no real improvement in the inlet performance at the low speeds, but did improve the inlet performance at the design conditions. Reducing the inlet flow rate improved the inlet performance, but at the likely expense of reduced thrust of the propulsion system. Deforming the cowl lip for low-speed operation of the inlet increased the inlet capture area and improved the inlet performance.

78 FR 66252 - Airworthiness Directives; Bell Helicopter Textron Canada Limited (Bell) Helicopters

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-05

... actions are intended to alert pilots to avoid certain engine speeds during steady- state operations...%. The proposed requirements were intended to alert pilots to avoid certain engine speeds during steady... the RFMs, advising pilots of the change, and installing a decal as described in Bell Alert Service...

14 CFR 23.1563 - Airspeed placards.

Code of Federal Regulations, 2012 CFR

2012-01-01

... than 6,000 pounds maximum weight, and turbine engine-powered airplanes, the maximum value of the minimum control speed, VMC (one-engine-inoperative) determined under § 23.149(b). [Amdt. 23-7, 34 FR 13097... lighted area such as the landing gear control and the airspeed indicator has features such as low speed...

NACA Aircraft on Lakebed - D-558-2, X-1B, and X-1E

NASA Technical Reports Server (NTRS)

1955-01-01

Early NACA research aircraft on the lakebed at the High Speed Research Station in 1955: Left to right: X-1E, D-558-2, X-1B There were four versions of the original Bell X-1 rocket-powered research aircraft that flew at the NACA High-Speed Flight Research Station, Edwards, California. The bullet-shaped X-1 aircraft were built by Bell Aircraft Corporation, Buffalo, N.Y. for the U.S. Army Air Forces (after 1947, U.S. Air Force) and the National Advisory Committee for Aeronautics (NACA). The X-1 Program was originally designated the XS-1 for EXperimental Supersonic. The X-1's mission was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier.' Three different X-1s were built and designated: X-1-1, X-1-2 (later modified to become the X-1E), and X-1-3. The basic X-1 aircraft were flown by a large number of different pilots from 1946 to 1951. The X-1 Program not only proved that humans could go beyond the speed of sound, it reinforced the understanding that technological barriers could be overcome. The X-1s pioneered many structural and aerodynamic advances including extremely thin, yet extremely strong wing sections; supersonic fuselage configurations; control system requirements; powerplant compatibility; and cockpit environments. The X-1 aircraft were the first transonic-capable aircraft to use an all-moving stabilizer. The flights of the X-1s opened up a new era in aviation. The first X-1 was air-launched unpowered from a Boeing B-29 Superfortress on January 25, 1946. Powered flights began in December 1946. On October 14, 1947, the X-1-1, piloted by Air Force Captain Charles 'Chuck' Yeager, became the first aircraft to exceed the speed of sound, reaching about 700 miles per hour (Mach 1.06) and an altitude of 43,000 feet. The number 2 X-1 was modified and redesignated the X-1E. The modifications included adding a conventional canopy, an ejection seat, a low-pressure fuel system of increased capacity, and a thinner high-speed wing. The X-1E was used to obtain in-flight data at twice the speed of sound, with particular emphasis placed on investigating the improvements achieved with the high-speed wing. These wings, made by Stanley Aircraft, were only 3-3/8-inches thick at the root and had 343 gauges installed in them to measure structural loads and aerodynamic heating. The X-1E used its rocket engine to power it up to a speed of 1,471 miles per hour (Mach 2.24) and to an altitude of 73,000 feet. Like the X-1 it was air-launched. The X-1 aircraft were almost 31 feet long and had a wingspan of 28 feet. The X-1 was built of conventional aluminum stressed-skin construction to extremely high structural standards. The X-1E was also 31 feet long but had a wingspan of only 22 feet, 10 inches. It was powered by a Reaction Motors, Inc., XLR-8-RM-5, four-chamber rocket engine. As did all X-1 rocket engines, the LR-8-RM-5 engine did not have throttle capability, but instead, depended on ignition of any one chamber or group of chambers to vary speed. The X-1A, X-1B, and the X-1D were growth versions of the X-1. They were almost five feet longer, almost 2,500 pounds heavier and had conventional canopies. The X-1A and X-1B were modified to have ejection seats. Their mission was to continue the X-1 studies at higher speeds and altitudes. The X-1A began this research after the X-1D was destroyed in an explosion on a captive flight before it made any research flights. On December 12, 1953, Major Charles Yeager flew the X-1A up to a speed of 1,612 miles per hour (almost two-and-a-half times the speed of sound). Then on August 26, 1954, Major Arthur Murray took the X-1A up to an altitude of 90,440 feet. Those two performances were the records for the X-1 program. Later the X-1A was also destroyed after being jettisoned from the carrier aircraft because of an explosion. The X-1B was fitted with 300 thermocouples for exploratory aerodynamic heating tests. It also was the first aircraft to fly with a reaction control system, a prototype of the system used on the X-15. The X-1C was cancelled before production. Three D-558-2 'Skyrockets' were built by Douglas Aircraft, Inc. for NACA and the Navy. The mission of the D-558-2 program was to investigate the flight characteristics of a swept-wing aircraft at high supersonic speeds. Particular attention was given to the problem of 'pitch-up,' a phenomenon often encountered with swept-wing configured aircraft. The D-558-2 was a single-place, 35-degree swept-wing aircraft measuring 42 feet in length. It was 12 feet, 8 inches in height and had a wingspan of 25 feet. Fully fueled it weighed from about 10,572 pounds to 15,787 pounds depending on configuration. The first of the three D-558-IIs had a Westinghouse J34-40 jet engine and took off under its own power. The second was equipped with a turbojet engine replaced in 1950 with a Reaction Motors Inc. LR8-RM-6 rocket engine. This aircraft was modified so it could be air-launched from a P2B-1S (Navy designation for the B-29) carrier aircraft. The third Skyrocket had the jet engine and the rocket engine but was also modified so it could be air-launched. The jet engine was for takeoff and climbing to altitude and the four-chambered rocket engine was for reaching supersonic speeds. The rocket engine was rated at 6,000 pounds of thrust. The D-558-2 was first flown on Feb. 4, 1948, by John Martin, a Douglas test pilot. A NACA pilot, Scott Crossfield, became the first person to fly faster than twice the speed of sound when he piloted the D-558-II to its maximum speed of 1,291 miles per hour on Nov. 20, 1953. Its peak altitude, 83,235 feet, a record in its day, was reached with USMC Lt. Col. Marion Carl behind the controls.

Acoustic testing of a supersonic tip speed fan with acoustic treatment and rotor casting slots. Quiet engine program scale model fan C

NASA Technical Reports Server (NTRS)

Kazin, S. B.

1973-01-01

Acoustic tests were conducted on a high tip speed (1550 ft/sec, 472.44 m/sec) single stage fan with varying amounts of wall acoustic treatment and with circumferential slots over the rotor blade tips. The slots were also tested with acoustic treatment placed behind the slots. The wall treatment results show that the inlet treatment is more effective at high fan speeds and aft duct treatment is more effective at low fan speeds. Maximum PNL's on a 200-foot (60.96 m) sideline show the untreated slots to have increased the rear radiated noise at approach. However, when the treatment was added to the slots inlet radiated noise was decreased, resulting in little change relative to the solid casing on an EPNL basis.

Experimental Determination of Linear Dynamics of Two-Spool Turbojet Engines

NASA Technical Reports Server (NTRS)

Novik, David; Heppler, Herbert

1954-01-01

Transfer functions descriptive of the response of most engine variables were determined from transient data that were obtained from approximate step inputs in fuel flow and in exhaust-nozzle area. The speed responses of both spools to fuel flow and to turbine-inlet temperature appeared as identical first-order lags. Response to exhaust-nozzle area was characterized by a first-order lag response of the outer-spool speed, accompanied by virtually no change in inner-spool speed.

Cryogenic gear technology for an orbital transfer vehicle engine and tester design

NASA Technical Reports Server (NTRS)

Calandra, M.; Duncan, G.

1986-01-01

Technology available for gears used in advanced Orbital Transfer Vehicle rocket engines and the design of a cryogenic adapted tester used for evaluating advanced gears are presented. The only high-speed, unlubricated gears currently in cryogenic service are used in the RL10 rocket engine turbomachinery. Advanced rocket engine gear systems experience operational load conditions and rotational speed that are beyond current experience levels. The work under this task consisted of a technology assessment and requirements definition followed by design of a self-contained portable cryogenic adapted gear test rig system.

Impact of air conditioning system operation on increasing gases emissions from automobile

NASA Astrophysics Data System (ADS)

Burciu, S. M.; Coman, G.

2016-08-01

The paper presents a study concerning the influence of air conditioning system operation on the increase of gases emissions from cars. The study focuses on urban operating regimes of the automobile, regimes when the engines have low loads or are operating at idling. Are presented graphically the variations of pollution emissions (CO, CO2, HC) depending of engine speed and the load on air conditioning system. Additionally are presented, injection duration, throttle position, the mechanical power required by the compressor of air conditioning system and the refrigerant pressure variation on the discharge path, according to the stage of charging of the air conditioning system.

The Waukesha Turbocharger Control Module: A tool for improved engine efficiency and response

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

Zurlo, J.R.; Reinbold, E.O.; Mueller, J.

1996-12-31

The Waukesha Turbocharger Control Module allows optimum control of turbochargers on lean burn gaseous fueled engines. The Turbocharger Control Module is user programmed to provide either maximum engine efficiency or best engine response to load changes. In addition, the Turbocharger Control Module prevents undesirable turbocharger surge. The Turbocharger Control Module consists of an electronic control box, engine speed, intake manifold pressure, ambient temperature sensors, and electric actuators driving compressor bypass and wastegate valves. The Turbocharger Control Module expands the steady state operational environment of the Waukesha AT27GL natural gas engine from sea level to 1,525 m altitude with one turbochargermore » match and improves the engine speed turn down by 80 RPM. Finally, the Turbocharger Control Module improves engine response to load changes.« less

Idle emissions from heavy-duty diesel vehicles: review and recent data.

PubMed

Khan, A B M S; Clark, Nigel N; Thompson, Gregory J; Wayne, W Scott; Gautam, Mridul; Lyons, Donald W; Hawelti, Daniel

2006-10-01

Heavy-duty diesel vehicle idling consumes fuel and reduces atmospheric quality, but its restriction cannot simply be proscribed, because cab heat or air-conditioning provides essential driver comfort. A comprehensive tailpipe emissions database to describe idling impacts is not yet available. This paper presents a substantial data set that incorporates results from the West Virginia University transient engine test cell, the E-55/59 Study and the Gasoline/Diesel PM Split Study. It covered 75 heavy-duty diesel engines and trucks, which were divided into two groups: vehicles with mechanical fuel injection (MFI) and vehicles with electronic fuel injection (EFI). Idle emissions of CO, hydrocarbon (HC), oxides of nitrogen (NOx), particulate matter (PM), and carbon dioxide (CO2) have been reported. Idle CO2 emissions allowed the projection of fuel consumption during idling. Test-to-test variations were observed for repeat idle tests on the same vehicle because of measurement variation, accessory loads, and ambient conditions. Vehicles fitted with EFI, on average, emitted approximately 20 g/hr of CO, 6 g/hr of HC, 86 g/hr of NOx, 1 g/hr of PM, and 4636 g/hr of CO2 during idle. MFI equipped vehicles emitted approximately 35 g/hr of CO, 23 g/hr of HC, 48 g/hr of NOx, 4 g/hr of PM, and 4484 g/hr of CO2, on average, during idle. Vehicles with EFI emitted less idle CO, HC, and PM, which could be attributed to the efficient combustion and superior fuel atomization in EFI systems. Idle NOx, however, increased with EFI, which corresponds with the advancing of timing to improve idle combustion. Fuel injection management did not have any effect on CO2 and, hence, fuel consumption. Use of air conditioning without increasing engine speed increased idle CO2, NOx, PM, HC, and fuel consumption by 25% on average. When the engine speed was elevated from 600 to 1100 revolutions per minute, CO2 and NOx emissions and fuel consumption increased by >150%, whereas PM and HC emissions increased by approximately 100% and 70%, respectively. Six Detroit Diesel Corp. (DDC) Series 60 engines in engine test cell were found to emit less CO, NOx, and PM emissions and consumed fuel at only 75% of the level found in the chassis dynamometer data. This is because fan and compressor loads were absent in the engine test cell.

The Effects of Engine Speed and Mixture Temperature on the Knocking Characteristics of Several Fuels

DTIC Science & Technology

1940-07-01

only. NACA list dtd 28 Sep 1945; NASA TR Server website ‘ ,f. ; :,““’? ,. .--:- .— #..- “W!+ ‘ ‘:u:i’w W9SlFlCAT10#CAME1lEO~ . TilCH131CAL NOTES...A photograph of the engine ’”used.is shown in figure 1. The electric air heater is above the engine and the cathod.e- ray oscill”ograph used as a...indicated that increasing the con- “press,ion ratio fro@ 6 to 11 results in.’a decie~se in the ‘dbzisity correction fact-or of shout . “0.030 at 1,500

49 CFR 229.117 - Speed indicators.

Code of Federal Regulations, 2012 CFR

2012-10-01

... locomotive at speeds in excess of 20 miles per hour shall be equipped with a speed indicator which is— (1) Accurate within ±3 miles per hour of actual speed at speeds of 10 to 30 miles per hour and accurate within ±5 miles per hour at speeds above 30 miles per hour; and (2) Clearly readable from the engineer's...

49 CFR 229.117 - Speed indicators.

Code of Federal Regulations, 2013 CFR

2013-10-01

... locomotive at speeds in excess of 20 miles per hour shall be equipped with a speed indicator which is— (1) Accurate within ±3 miles per hour of actual speed at speeds of 10 to 30 miles per hour and accurate within ±5 miles per hour at speeds above 30 miles per hour; and (2) Clearly readable from the engineer's...

49 CFR 229.117 - Speed indicators.

Code of Federal Regulations, 2014 CFR

2014-10-01

... locomotive at speeds in excess of 20 miles per hour shall be equipped with a speed indicator which is— (1) Accurate within ±3 miles per hour of actual speed at speeds of 10 to 30 miles per hour and accurate within ±5 miles per hour at speeds above 30 miles per hour; and (2) Clearly readable from the engineer's...

Preliminary results on performance testing of a turbocharged rotary combustion engine

NASA Technical Reports Server (NTRS)

Meng, P. R.; Rice, W. J.; Schock, H. J.; Pringle, D. P.

1982-01-01

The performance of a turbocharged rotary engine at power levels above 75 kW (100 hp) was studied. A twin rotor turbocharged Mazda engine was tested at speeds of 3000 to 6000 rpm and boost pressures to 7 psi. The NASA developed combustion diagnostic instrumentation was used to quantify indicated and pumping mean effect pressures, peak pressure, and face to face variability on a cycle by cycle basis. Results of this testing showed that a 5900 rpm a 36 percent increase in power was obtained by operating the engine in the turbocharged configuration. When operating with lean carburetor jets at 105 hp (78.3 kW) and 4000 rpm, a brake specific fuel consumption of 0.45 lbm/lb-hr was measured.

An airline study of advanced technology requirements for advanced high speed commercial transport engines. 2: Engine preliminary design assessment

NASA Technical Reports Server (NTRS)

Sallee, G. P.

1973-01-01

The advanced technology requirements for an advanced high speed commercial transport engine are presented. The results of the phase 2 study effort cover the following areas: (1) general review of preliminary engine designs suggested for a future aircraft, (2) presentation of a long range view of airline propulsion system objectives and the research programs in noise, pollution, and design which must be undertaken to achieve the goals presented, (3) review of the impact of propulsion system unreliability and unscheduled maintenance on cost of operation, (4) discussion of the reliability and maintainability requirements and guarantees for future engines.

Parametric tests of a traction drive retrofitted to an automotive gas turbine

NASA Technical Reports Server (NTRS)

Rohn, D. A.; Lowenthal, S. H.; Anderson, N. E.

1980-01-01

The results of a test program to retrofit a high performance fixed ratio Nasvytis Multiroller Traction Drive in place of a helical gear set to a gas turbine engine are presented. Parametric tests up to a maximum engine power turbine speed of 45,500 rpm and to a power level of 11 kW were conducted. Comparisons were made to similar drives that were parametrically tested on a back-to-back test stand. The drive showed good compatibility with the gas turbine engine. Specific fuel consumption of the engine with the traction drive speed reducer installed was comparable to the original helical gearset equipped engine.

High-Temperature Magnetic Bearings for Gas Turbine Engines

NASA Technical Reports Server (NTRS)

1996-01-01

Magnetic bearings are the subject of a new NASA Lewis Research Center and U.S. Army thrust with significant industry participation, and coordination with other Government agencies. The NASA/Army emphasis is on high-temperature applications for future gas turbine engines. Magnetic bearings could increase the reliability and reduce the weight of these engines by eliminating the lubrication system. They could also increase the DN (diameter of the bearing times rpm) limit on engine speed and allow active vibration cancellation systems to be used--resulting in a more efficient, "more electric" engine. Finally, the Integrated High-Performance Turbine Engine Technology (IHPTET) Program, a joint Department of Defense/industry program, identified a need for a hightemperature (as high as 1200 F) magnetic bearing that could be demonstrated in a phase III engine. This magnetic bearing is similar to an electric motor. It has a laminated rotor and stator made of cobalt steel. Wound around the stator are a series of electrical wire coils that form a series of electric magnets around the circumference. The magnets exert a force on the rotor. A probe senses the position of the rotor, and a feedback controller keeps it in the center of the cavity. The engine rotor, bearings, and case form a flexible structure that contains a large number of modes. The bearing feedback controller, which could cause some of these modes to become unstable, could be adapted to varying flight conditions to minimize seal clearances and monitor the health of the system. Cobalt steel has a curie point greater than 1700 F, and copper wire has a melting point beyond that. Therefore, practical limitations associated with the maximum magnetic field strength in the cobalt steel and the stress in the rotating components limit the temperature to about 1200 F. The objective of this effort is to determine the limits in temperature and speed of a magnetic bearing operating in an engine. Our approach is to use our in-house experience in magnets, mechanical components, high-temperature materials, and surface lubrication to build and test a magnetic bearing in both a rig and an engine. Testing will be done at Lewis or through cooperative programs in industrial facilities.

Simulation of Aircraft Engine Blade-Out Structural Dynamics

NASA Technical Reports Server (NTRS)

Lawrence, Charles; Carney, Kelly; Gallardo, Vicente

2001-01-01

A primary concern of aircraft structure designers is the accurate simulation of the blade-out event and the subsequent windmilling of the engine. Reliable simulations of the blade-out event are required to insure structural integrity during flight as well as to guarantee successful blade-out certification testing. The system simulation includes the lost blade loadings and the interactions between the rotating turbomachinery and the remaining aircraft structural components. General-purpose finite element structural analysis codes such as MSC NASTRAN are typically used and special provisions are made to include transient effects from the blade loss and rotational effects resulting from the engine's turbomachinery. The present study provides the equations of motion for rotordynamic response including the effect of spooldown speed and rotor unbalance and examines the effects of these terms on a cantilevered rotor. The effect of spooldown speed is found to be greater with increasing spooldown rate. The parametric term resulting from the mass unbalance has a more significant effect on the rotordynamic response than does the spooldown term. The parametric term affects both the peak amplitudes as well as the resonant frequencies of the rotor.

Simulation of Aircraft Engine Blade-Out Structural Dynamics. Revised

NASA Technical Reports Server (NTRS)

Lawrence, Charles; Carney, Kelly; Gallardo, Vicente

2001-01-01

A primary concern of aircraft structure designers is the accurate simulation of the blade-out event and the subsequent windmilling of the engine. Reliable simulations of the blade-out event are required to insure structural integrity during flight as well as to guarantee successful blade-out certification testing. The system simulation includes the lost blade loadings and the interactions between the rotating turbomachinery and the remaining aircraft structural components. General-purpose finite element structural analysis codes such as MSC NASTRAN are typically used and special provisions are made to include transient effects from the blade loss and rotational effects resulting from the engine's turbomachinery. The present study provides the equations of motion for rotordynamic response including the effect of spooldown speed and rotor unbalance and examines the effects of these terms on a cantilevered rotor. The effect of spooldown speed is found to be greater with increasing spooldown rate. The parametric term resulting from the mass unbalance has a more significant effect on the rotordynamic response than does the spooldown term. The parametric term affects both the peak amplitudes as well as the resonant frequencies of the rotor.

Evaluation of End Mill Coatings

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

L. J. Lazarus; R. L. Hester,

2005-08-01

Milling tests were run on families of High Speed Steel (HSS) end mills to determine their lives while machining 304 Stainless Steel. The end mills tested were made from M7, M42 and T15-CPM High Speed Steels. The end mills were also evaluated with no coatings as well as with Titanium Nitride (TiN) and Titanium Carbo-Nitride (TiCN) coatings to determine which combination of HSS and coating provided the highest increase in end mill life while increasing the cost of the tool the least. We found end mill made from M42 gave us the largest increase in tool life with the leastmore » increase in cost. The results of this study will be used by Cutting Tool Engineering in determining which end mill descriptions will be dropped from our tool catalog.« less

Engineering Design Handbook. Helicopter Engineering. Part Two. Detail Design

DTIC Science & Technology

1976-01-01

rates are sp-ed for a given amount of power available, involved in both symmetrical and turning maneu- Normally•, the high - speed performance problem...safe mnain rotor specls. cessive oiling should be avoided. Good estimations of The power losses of a typical high - speed twin- gear windage losses F...rotor gearbox and consise.d of two hy- gearbox is pitting or spa,:,iig of the gears and draulic pumps and a high - speed generator. bearinbs (par. 4-2.1

Progress in Open Rotor Research: A U.S. Perspective

NASA Technical Reports Server (NTRS)

Van Zante, Dale E.

2015-01-01

In response to the 1970s oil crisis, NASA created the Advanced Turboprop Project (ATP) to mature technologies for high-speed propellers to enable large reductions in fuel burn relative to turbofan engines of that era. Both single rotation and contra- rotation concepts were designed and tested in ground based facilities as well as flight. Some novel concepts/configurations were proposed as part of the effort. The high-speed propeller concepts did provide fuel burn savings, albeit with some acoustics and structural challenges to overcome. When fuel prices fell, the business case for radical new engine configurations collapsed and the research emphasis returned to high bypass ducted configurations. With rising oil prices and increased environmental concerns there is renewed interest in high-speed propeller based engine architectures. Contemporary analysis tools for aerodynamics and aeroacoustics have enabled a new era of blade designs that have both high efficiency and lower noise characteristics. A recent series of tests in the U.S. have characterized the aerodynamic performance and noise from these modern contra-rotating propeller designs. Additionally the installation and noise shielding aspects for conventional airframes and blended wing bodies have been studied. Historical estimates of 'propfan' performance have relied on legacy propeller performance and acoustics data. Current system studies make use of the modern propeller data and higher fidelity installation effects data to estimate the performance of a contemporary aircraft system. Contemporary designs have demonstrated high net efficiency, approximately 86%, at 0.78 Mach, and low noise, greater than 15 EPNdB cumulative margin to Chapter 4 when analyzed on a NASA derived aircraft/mission. This paper presents the current state of high-speed propeller/open rotor research within the U.S. from an overall viewpoint of the various efforts ongoing. The remaining technical challenges to a production engine include propulsion airframe integration, acoustic sensitivity to aircraft weight and certification issues.

Towards a renewal of the propeller in aeronautics

NASA Technical Reports Server (NTRS)

Berger, D.; Jacquet, P.

1985-01-01

The reasons for reconsidering the propeller for aircraft propulsion, the areas of application, and necessary developments are considered. Rising fuel costs and an increasing theoretical and experimental data base for turboprop engines have demonstrated that significant cost savings can be realized by the use of propellers. Propellers are well-suited to powering aircraft traveling at speeds up to Mach 0.65. Work is progressing on the development of a 150 seat aircraft which has a cruise speed of Mach 0.8, powered by a turboprop attached to an engine of 15,000 shp. Aeroelasticity analyses ae necessary in order to characterize the behavior of thin profile propfan blades, particularly to predict the oscillations through the entire functional range. High-power reducers must be developed, and the level of cabin noise must be controlled to less than 90 dB. Commercial applications are predicted for turboprops in specific instances.

Numerical Prediction of Combustion-induced Noise using a hybrid LES/CAA approach

NASA Astrophysics Data System (ADS)

Ihme, Matthias; Pitsch, Heinz; Kaltenbacher, Manfred

2006-11-01

Noise generation in technical devices is an increasingly important problem. Jet engines in particular produce sound levels that not only are a nuisance but may also impair hearing. The noise emitted by such engines is generated by different sources such as jet exhaust, fans or turbines, and combustion. Whereas the former acoustic mechanisms are reasonably well understood, combustion-generated noise is not. A methodology for the prediction of combustion-generated noise is developed. In this hybrid approach unsteady acoustic source terms are obtained from an LES and the propagation of pressure perturbations are obtained using acoustic analogies. Lighthill's acoustic analogy and a non-linear wave equation, accounting for variable speed of sound, have been employed. Both models are applied to an open diffusion flame. The effects on the far field pressure and directivity due to the variation of speed of sound are analyzed. Results for the sound pressure level will be compared with experimental data.

78 FR 65206 - Airworthiness Directives; Bell Helicopter Textron Canada Limited (Bell) Helicopters

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-31

... engine speeds during steady- state operations. These actions are intended to alert pilots to avoid... intended to alert pilots to avoid certain engine speeds during steady- state operations, prevent failure of... decal as described in Bell Alert Service Bulletin (ASB) No. 430-05-34, dated June 10, 2005 (ASB 430-05...

78 FR 65200 - Airworthiness Directives; Bell Helicopter Textron Canada Limited (Bell) Helicopters

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-31

... vibrations at certain engine speeds during steady- state operations. These actions are intended to alert... proposed requirements were intended to alert pilots to avoid certain engine speeds during steady-state... the change, and installing a decal as described in Bell Alert Service Bulletin (ASB) No. 407-05-67...

Stratified charge rotary engine - Internal flow studies at the MSU engine research laboratory

NASA Technical Reports Server (NTRS)

Hamady, F.; Kosterman, J.; Chouinard, E.; Somerton, C.; Schock, H.; Chun, K.; Hicks, Y.

1989-01-01

High-speed visualization and laser Doppler velocimetry (LDV) systems consisting of a 40-watt copper vapor laser, mirrors, cylindrical lenses, a high speed camera, a synchronization timing system, and a particle generator were developed for the study of the fuel spray-air mixing flow characteristics within the combustion chamber of a motored rotary engine. The laser beam is focused down to a sheet approximately 1 mm thick, passing through the combustion chamber and illuminates smoke particles entrained in the intake air. The light scattered off the particles is recorded by a high speed rotating prism camera. Movies are made showing the air flow within the combustion chamber. The results of a movie showing the development of a high-speed (100 Hz) high-pressure (68.94 MPa, 10,000 psi) fuel jet are also discussed. The visualization system is synchronized so that a pulse generated by the camera triggers the laser's thyratron.

Design of a high-speed digital processing element for parallel simulation

NASA Technical Reports Server (NTRS)

Milner, E. J.; Cwynar, D. S.

1983-01-01

A prototype of a custom designed computer to be used as a processing element in a multiprocessor based jet engine simulator is described. The purpose of the custom design was to give the computer the speed and versatility required to simulate a jet engine in real time. Real time simulations are needed for closed loop testing of digital electronic engine controls. The prototype computer has a microcycle time of 133 nanoseconds. This speed was achieved by: prefetching the next instruction while the current one is executing, transporting data using high speed data busses, and using state of the art components such as a very large scale integration (VLSI) multiplier. Included are discussions of processing element requirements, design philosophy, the architecture of the custom designed processing element, the comprehensive instruction set, the diagnostic support software, and the development status of the custom design.

Experimental investigation on regulated and unregulated emissions of a diesel engine fueled with ultra-low sulfur diesel fuel blended with biodiesel from waste cooking oil.

PubMed

Di, Yage; Cheung, C S; Huang, Zuohua

2009-01-01

Experiments were conducted on a 4-cylinder direct-injection diesel engine using ultra-low sulfur diesel, bi oesel and their blends, to investigate the regulated and unregulated emissions of the engine under five engine loads at an engine speed of 1800 rev/min. Blended fuels containing 19.6%, 39.4%, 59.4% and 79.6% by volume of biodiesel, corresponding to 2%, 4%, 6% and 8% by mass of oxygen in the blended fuel, were used. Biodiesel used in this study was converted from waste cooking oil. The following results are obtained with an increase of biodiesel in the fuel. The brake specific fuel consumption and the brake thermal efficiency increase. The HC and CO emissions decrease while NO(x) and NO(2) emissions increase. The smoke opacity and particulate mass concentrations reduce significantly at high engine load. In addition, for submicron particles, the geometry mean diameter of the particles becomes smaller while the total number concentration increases. For the unregulated gaseous emissions, generally, the emissions of formaldehyde, 1,3-butadiene, toluene, xylene decrease, however, acetaldehyde and benzene emissions increase. The results indicate that the combination of ultra-low sulfur diesel and biodiesel from waste cooking oil gives similar results to those in the literature using higher sulfur diesel fuels and biodiesel from other sources.

Control Performance of General Electric Fuel and Torque Regulator Operating on T31-3 Turbine-Propeller Engine in Sea-Level Test Stand

NASA Technical Reports Server (NTRS)

Oppenheimer, Frank L.; Lazar, James

1951-01-01

A .General Electric fuel and torque regulator was tested in conjunction with a T31-3 turbine-propeller engine in the sea-level static test stand at the NACA Lewis laboratory. The engine and control were operated over the entire speed range: 11,000 rpm, nominal flight idle, to 13,000 rpm, full power. Steady-state and transient data were recorded and are presented with a description of the four control loops being used in the system. Results of this investigation indicated that single-lever control operation was satisfactory under conditions of test. Transient data presented showed that turbine-outlet temperature did overshoot maximum operating value on acceleration but that the time duration of overshoot did not exceed approximately 1 second. This temperature limiting resulted from a control on fuel flow as a function of engine speed. Speed and torque first reached their desired values 0.4 second from the time of change in power-setting lever position. Maximum speed overshoot was 3 percent.

Analysis of heat recovery of diesel engine using intermediate working fluid

NASA Astrophysics Data System (ADS)

Jin, Lei; Zhang, Jiang; Tan, Gangfeng; Liu, Huaming

2017-07-01

The organic Rankine cycle (ORC) is an effective way to recovery the engine exhaust heat. The thermal stability of the evaporation system is significant for the stable operation of the ORC system. In this paper, the performance of the designed evaporation system which combines with the intermediate fluid for recovering the exhaust waste heat from a diesel engine is evaluated. The thermal characteristics of the target diesel engine exhaust gas are evaluated based on the experimental data firstly. Then, the mathematical model of the evaporation system is built based on the geometrical parameters and the specific working conditions of ORC. Finally, the heat transfer characteristics of the evaporation system are estimated corresponding to three typical operating conditions of the diesel engine. The result shows that the exhaust temperature at the evaporator outlet increases slightly with the engine speed and load. In the evaporator, the heat transfer coefficient of the Rankine working fluid is slightly larger than the intermediate fluid. However, the heat transfer coefficient of the intermediate fluid in the heat exchanger is larger than the exhaust side. The heat transfer areas of the evaporator in both the two-phase zone and the preheated zone change slightly along with the engine working condition while the heat transfer areas of the overheated zone has changed obviously. The maximum heat transfer rate occurs in the preheating zone while the minimum value occurs in the overheating zone. In addition, the Rankine working fluid temperature at the evaporator outlet is not sensitively affected by the torque and speed of the engine and the organic fluid flow is relatively stable. It is concluded that the intermediate fluid could effectively reduce the physical changes of Rankine working fluid in the evaporator outlet due to changes in engine operating conditions.

Foil Bearing Starting Considerations and Requirements for Rotorcraft Engine Applications

NASA Technical Reports Server (NTRS)

Radil, Kevin C.; DellaCorte, Christopher

2009-01-01

Foil gas bearings under development for rotorcraft-sized, hot core engine applications have been susceptible to damage from the slow acceleration and rates typically encountered during the pre-ignition stage in conventional engines. Recent laboratory failures have been assumed to be directly linked to operating foil bearings below their lift-off speed while following conventional startup procedures for the engines. In each instance, the continuous sliding contact between the foils and shaft was believed to thermally overload the bearing and cause the engines to fail. These failures highlight the need to characterize required acceleration rates and minimum operating speeds for these applications. In this report, startup experiments were conducted with a large, rotorcraft engine sized foil bearing under moderate load and acceleration rates to identify the proper start procedures needed to avoid bearing failure. The results showed that a bearing under a 39.4 kPa static load can withstand a modest acceleration rate of 500 rpm/s and excessive loitering below the bearing lift-off speed provided an adequate solid lubricant is present.

Multivariate statistical analysis strategy for multiple misfire detection in internal combustion engines

NASA Astrophysics Data System (ADS)

Hu, Chongqing; Li, Aihua; Zhao, Xingyang

2011-02-01

This paper proposes a multivariate statistical analysis approach to processing the instantaneous engine speed signal for the purpose of locating multiple misfire events in internal combustion engines. The state of each cylinder is described with a characteristic vector extracted from the instantaneous engine speed signal following a three-step procedure. These characteristic vectors are considered as the values of various procedure parameters of an engine cycle. Therefore, determination of occurrence of misfire events and identification of misfiring cylinders can be accomplished by a principal component analysis (PCA) based pattern recognition methodology. The proposed algorithm can be implemented easily in practice because the threshold can be defined adaptively without the information of operating conditions. Besides, the effect of torsional vibration on the engine speed waveform is interpreted as the presence of super powerful cylinder, which is also isolated by the algorithm. The misfiring cylinder and the super powerful cylinder are often adjacent in the firing sequence, thus missing detections and false alarms can be avoided effectively by checking the relationship between the cylinders.

Some Effects of Injection Advance Angle, Engine-Jacket Temperature, and Speed on Combustion in a Compression-Ignition Engine

NASA Technical Reports Server (NTRS)

Rothrock, A M; Waldron, C D

1936-01-01

An optical indicator and a high-speed motion-picture camera capable of operating at the rate of 2,000 frames per second were used to record simultaneously the pressure development and the flame formation in the combustion chamber of the NACA combustion apparatus. Tests were made at engine speeds of 570 and 1,500 r.p.m. The engine-jacket temperature was varied from 100 degrees to 300 degrees F. And the injection advance angle from 13 degrees after top center to 120 degrees before top center. The results show that the course of the combustion is largely controlled by the temperature and pressure of the air in the chamber from the time the fuel is injected until the time at which combustion starts and by the ignition lag. The conclusion is presented that in a compression-ignition engine with a quiescent combustion chamber the ignition lag should be the longest that can be used without excessive rates of pressure rise; any further shortening of the ignition lag decreased the effective combustion of the engine.

High-Speed, High-Temperature Finger Seal Test Evaluated

NASA Technical Reports Server (NTRS)

Proctor, Margaret P.

2003-01-01

A finger seal, designed and fabricated by Honeywell Engines, Systems and Services, was tested at the NASA Glenn Research Center at surface speeds up to 1200 ft/s, air temperatures up to 1200 F, and pressures across the seal of 75 psid. These are the first test results obtained with NASA s new High-Temperature, High-Speed Turbine Seal Test Rig (see the photograph). The finger seal is an innovative design recently patented by AlliedSignal Engines, which has demonstrated considerably lower leakage than commonly used labyrinth seals and is considerably cheaper than brush seals. The cost to produce finger seals is estimated to be about half of the cost to produce brush seals. Replacing labyrinth seals with fingers seals at locations that have high-pressure drops in gas turbine engines, typically main engine and thrust seals, can reduce air leakage at each location by 50 percent or more. This directly results in a 0.7- to 1.4-percent reduction in specific fuel consumption and a 0.35- to 0.7-percent reduction in direct operating costs . Because the finger seal is a contacting seal, this testing was conducted to address concerns about its heat generation and life capability at the higher speeds and temperatures required for advanced engines. The test results showed that the seal leakage and wear performance are acceptable for advanced engines.

F1 style MGU-H applied to the turbocharger of a gasoline hybrid electric passenger car

NASA Astrophysics Data System (ADS)

Boretti, Albert

2017-12-01

We consider a turbocharged gasoline direct injection (DI) engine featuring a motor-generator-unit (MGU-H) fitted on the turbocharger shaft. The MGU-H receives or delivers energy to the same energy storage (ES) of the hybrid power unit that comprises a motor-generator unit on the driveline (MGU-K) in addition to the internal combustion engine (ICE). The energy supply from the ES is mostly needed during sharp accelerations to avoid turbo-lag, and to boost torque at low speeds. At low speeds, it also improves the ratio of engine crankshaft power to fuel flow power, as well as the ratio of engine crankshaft plus turbocharger shaft power to fuel flow power. The energy supply to the ES is possible at high speeds and loads, where otherwise the turbine could have been waste gated, and during decelerations. This improves the ratio of engine crankshaft plus turbocharger shaft power to fuel flow power.

CARBONYL CONTENT OF DIESEL EXHAUST FROM TWO SOURCES AND POSSIBLE IMPLICATIONS FOR CELL RESPONSES

EPA Science Inventory

Diesel exhaust is known to cause health effects including increases in lung inflammation and altered immunological parameters. The diesel exhausts used in our studies were collected into ice-cooled PBS from a diesel engine running at idle speed (DE2A) or at full load (DE5A). P...

Performance of a 13-Stage Development Compressor for the J40-WE-24 Engine at Equivalent Speeds from 30 to 112 Percent of Design

NASA Technical Reports Server (NTRS)

Hatch, James E.; Lucas, James G.; Finger, Harold B.

1953-01-01

The performance of a 13-stage development comressor for the J40-WE-24 engine has been determined at equivalent speeds from 30 to 112 percent of design. The design total-pressure ratio of 6.0 and the design weight flow of 164 pounds per second were not attained, An analysis was conducted to determine the reasons for the poor performance at the design and over-design speed. The analysis indicated that most of the difficulty could be attributed to the fact that the first stage was overcompromised to favor part-speed performance,

Performance of J33 turbojet engine with shaft-power extraction III : turbine performance

NASA Technical Reports Server (NTRS)

Huppert, M C; Nettles, J C

1949-01-01

The performance of the turbine component of a J33 turbojet engine was determined over a range of turbine speeds from 8000 to 11,500 rpm.Turbine-inlet temperature was varied from the minimum required to drive the compressor to a maximum of approximately 2000 degrees R at each of several intermediate turbine speeds. Data are presented that show the horsepower developed by the turbine per pound of gas flow. The relation between turbine-inlet stagnation pressure, turbine-outlet stagnation pressure, and turbine-outlet static pressure was established. The turbine-weight-flow parameter varied from 39.2 to 43.6. The maximum turbine efficiency measured was 0.86 at a pressure ratio of 3.5 and a ratio of blade speed to theoretical nozzle velocity of 0.39. A generalized performance map of the turbine-horsepower parameter plotted against the turbine-speed parameter indicated that the best turbine efficiency is obtained when the turbine power is 10 percent greater than the compressor horsepower. The variation of efficiency with the ratio of blade speed to nozzle velocity indicated that the turbine operates at a speed above that for maximum efficiency when the engine is operated normally with the 19-inch-diameter jet nozzle.

Examination of Wave Speed in Rotating Detonation Engines Using Simplified Computational Fluid Dynamics

NASA Technical Reports Server (NTRS)

Paxson, Daniel E.

2018-01-01

A simplified, two-dimensional, computational fluid dynamic (CFD) simulation, with a reactive Euler solver is used to examine possible causes for the low detonation wave propagation speeds that are consistently observed in air breathing rotating detonation engine (RDE) experiments. Intense, small-scale turbulence is proposed as the primary mechanism. While the solver cannot model this turbulence, it can be used to examine the most likely, and profound effect of turbulence. That is a substantial enlargement of the reaction zone, or equivalently, an effective reduction in the chemical reaction rate. It is demonstrated that in the unique flowfield of the RDE, a reduction in reaction rate leads to a reduction in the detonation speed. A subsequent test of reduced reaction rate in a purely one-dimensional pulsed detonation engine (PDE) flowfield yields no reduction in wave speed. The reasons for this are explained. The impact of reduced wave speed on RDE performance is then examined, and found to be minimal. Two other potential mechanisms are briefly examined. These are heat transfer, and reactive mixture non-uniformity. In the context of the simulation used for this study, both mechanisms are shown to have negligible effect on either wave speed or performance.

Aerodynamic Design of a Dual-Flow Mach 7 Hypersonic Inlet System for a Turbine-Based Combined-Cycle Hypersonic Propulsion System

NASA Technical Reports Server (NTRS)

Sanders, Bobby W.; Weir, Lois J.

2008-01-01

A new hypersonic inlet for a turbine-based combined-cycle (TBCC) engine has been designed. This split-flow inlet is designed to provide flow to an over-under propulsion system with turbofan and dual-mode scramjet engines for flight from takeoff to Mach 7. It utilizes a variable-geometry ramp, high-speed cowl lip rotation, and a rotating low-speed cowl that serves as a splitter to divide the flow between the low-speed turbofan and the high-speed scramjet and to isolate the turbofan at high Mach numbers. The low-speed inlet was designed for Mach 4, the maximum mode transition Mach number. Integration of the Mach 4 inlet into the Mach 7 inlet imposed significant constraints on the low-speed inlet design, including a large amount of internal compression. The inlet design was used to develop mechanical designs for two inlet mode transition test models: small-scale (IMX) and large-scale (LIMX) research models. The large-scale model is designed to facilitate multi-phase testing including inlet mode transition and inlet performance assessment, controls development, and integrated systems testing with turbofan and scramjet engines.

Acoustical design economic trade off for transport aircraft

NASA Astrophysics Data System (ADS)

Benito, A.

The effects of ICAO fixed certification limits and local ordinances on acoustic emissions from jets on commercial transport aircraft and costs of operations are explored. The regulations effectively ban some aircraft from operation over populated areas, impose curfews on airports and, in conjunction with local civil aviation rules, levy extra taxes and quotas on noisier equipment. Jet engine manufacturers have attempted to increase the flow laminarity, decrease the exhaust speed and develop acoustic liners for selected duct areas. Retrofits are, however, not usually cost effective due to increased operational costs, e.g., fuel consumption can increase after engine modification because of increased weight. Finally, an attempt is made to assess, monetarily, the costs of noise pollution, wherein fines are levied for noisy aircraft and the money is spent insulating homes from noise.

An Extended Combustion Model for the Aircraft Turbojet Engine

NASA Astrophysics Data System (ADS)

Rotaru, Constantin; Andres-Mihăilă, Mihai; Matei, Pericle Gabriel

2014-08-01

The paper consists in modelling and simulation of the combustion in a turbojet engine in order to find optimal characteristics of the burning process and the optimal shape of combustion chambers. The main focus of this paper is to find a new configuration of the aircraft engine combustion chambers, namely an engine with two main combustion chambers, one on the same position like in classical configuration, between compressor and turbine and the other, placed behind the turbine but not performing the role of the afterburning. This constructive solution could allow a lower engine rotational speed, a lower temperature in front of the first stage of the turbine and the possibility to increase the turbine pressure ratio by extracting the flow stream after turbine in the inner nozzle. Also, a higher thermodynamic cycle efficiency and thrust in comparison to traditional constant-pressure combustion gas turbine engines could be obtained.

Effects of mixing system and pilot fuel quality on diesel-biogas dual fuel engine performance.

PubMed

Bedoya, Iván Darío; Arrieta, Andrés Amell; Cadavid, Francisco Javier

2009-12-01

This paper describes results obtained from CI engine performance running on dual fuel mode at fixed engine speed and four loads, varying the mixing system and pilot fuel quality, associated with fuel composition and cetane number. The experiments were carried out on a power generation diesel engine at 1500 m above sea level, with simulated biogas (60% CH(4)-40% CO(2)) as primary fuel, and diesel and palm oil biodiesel as pilot fuels. Dual fuel engine performance using a naturally aspirated mixing system and diesel as pilot fuel was compared with engine performance attained with a supercharged mixing system and biodiesel as pilot fuel. For all loads evaluated, was possible to achieve full diesel substitution using biogas and biodiesel as power sources. Using the supercharged mixing system combined with biodiesel as pilot fuel, thermal efficiency and substitution of pilot fuel were increased, whereas methane and carbon monoxide emissions were reduced.

Control installation for the proportioning of a secondary air quantity for improvement of the combustion in internal combustion engines or the afterburning of the exhaust gases of internal combustion engines

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

Bockelmann, W.; Groezinger, H.; Woebky, P.U.

1977-01-04

A control installation is described for the dosing or proportioning of a secondary air quantity for the improvement of combustion in internal combustion engines, or the after-burning of the exhaust gases of internal combustion engines. An auxiliary arrangement is responsive to an emergency signal for effecting the prompt shutting-off of the secondary air. The emergency signal may be initiated in response to a failure in the ignition voltage of the internal combustion engine; an increase in the hydrocarbon content of the exhaust gases; a disparity between the position of the mixture dosing element and the engine rotational speed; the exceedingmore » of a limiting temperature in the exhaust gas manifold; or the exceeding of a limiting temperature in the afterburner.« less

Feasibility of water injection into the turbine coolant to permit gas turbine contingency power for helicopter application

NASA Technical Reports Server (NTRS)

Vanfossen, G. J.

1983-01-01

A system which would allow a substantially increased output from a turboshaft engine for brief periods in emergency situations with little or no loss of turbine stress rupture life is proposed and studied analytically. The increased engine output is obtained by overtemperaturing the turbine; however, the temperature of the compressor bleed air used for hot section cooling is lowered by injecting and evaporating water. This decrease in cooling air temperature can offset the effect of increased gas temperature and increased shaft speed and thus keep turbine blade stress rupture life constant. The analysis utilized the NASA-Navy-Engine-Program or NNEP computer code to model the turboshaft engine in both design and off-design modes. This report is concerned with the effect of the proposed method of power augmentation on the engine cycle and turbine components. A simple cycle turboshaft engine with a 16:1 pressure ratio and a 1533 K (2760 R) turbine inlet temperature operating at sea level static conditions was studied to determine the possible power increase and the effect on turbine stress rupture life that could be expected using the proposed emergency cooling scheme. The analysis showed a 54 percent increse in output power can be achieved with no loss in gas generator turbine stress rupture life. A 231 K (415 F) rise in turbine inlet temperature is required for this level of augmentation. The required water flow rate was found to be .0109 kg water per kg of engine air flow.

Preliminary Analysis for an Optimized Oil-Free Rotorcraft Engine Concept

NASA Technical Reports Server (NTRS)

Howard, Samuel A.; Bruckner, Robert J.; DellaCorte, Christopher; Radil, Kevin C.

2008-01-01

Recent developments in gas foil bearing technology have led to numerous advanced high-speed rotating system concepts, many of which have become either commercial products or experimental test articles. Examples include Oil-Free microturbines, motors, generators and turbochargers. The driving forces for integrating gas foil bearings into these high-speed systems are the benefits promised by removing the oil lubrication system. Elimination of the oil system leads to reduced emissions, increased reliability, and decreased maintenance costs. Another benefit is reduced power plant weight. For rotorcraft applications, this would be a major advantage, as every pound removed from the propulsion system results in a payload benefit. Implementing foil gas bearings throughout a rotorcraft gas turbine engine is an important long-term goal that requires overcoming numerous technological hurdles. Adequate thrust bearing load capacity and potentially large gearbox applied radial loads are among them. However, by replacing the turbine end, or hot section, rolling element bearing with a gas foil bearing many of the above benefits can be realized. To this end, engine manufacturers are beginning to explore the possibilities of hot section gas foil bearings in propulsion engines. This paper presents a logical follow-on activity by analyzing a conceptual rotorcraft engine to determine the feasibility of a foil bearing supported core. Using a combination of rotordynamic analyses and a load capacity model, it is shown to be reasonable to consider a gas foil bearing core section.

Increasing the resource of high load compression springs

NASA Astrophysics Data System (ADS)

Zemlyanushnova, N. Y.; Zemlyanushnov, N. A.

2017-10-01

Valve springs of VAZ automobiles’ engines are manufactured by using a new method. The decrease of dispersion of operating load in experimental springs compared to serial ones has been proved. The springs have passed a stress cycling test. With the new method having been used, it has been proved that the resource of high load springs working at high loading speed with coils collision has increased up to 60%.

Improving Engine Efficiency Through Core Developments

NASA Technical Reports Server (NTRS)

Heidmann, James D.

2011-01-01

The NASA Environmentally Responsible Aviation (ERA) Project and Fundamental Aeronautics Projects are supporting compressor and turbine research with the goal of reducing aircraft engine fuel burn and greenhouse gas emissions. The primary goals of this work are to increase aircraft propulsion system fuel efficiency for a given mission by increasing the overall pressure ratio (OPR) of the engine while maintaining or improving aerodynamic efficiency of these components. An additional area of work involves reducing the amount of cooling air required to cool the turbine blades while increasing the turbine inlet temperature. This is complicated by the fact that the cooling air is becoming hotter due to the increases in OPR. Various methods are being investigated to achieve these goals, ranging from improved compressor three-dimensional blade designs to improved turbine cooling hole shapes and methods. Finally, a complementary effort in improving the accuracy, range, and speed of computational fluid mechanics (CFD) methods is proceeding to better capture the physical mechanisms underlying all these problems, for the purpose of improving understanding and future designs.

Time Resolved Digital PIV Measurements of Flow Field Cyclic Variation in an Optical IC Engine

NASA Astrophysics Data System (ADS)

Jarvis, S.; Justham, T.; Clarke, A.; Garner, C. P.; Hargrave, G. K.; Halliwell, N. A.

2006-07-01

Time resolved digital particle image velocimetry (DPIV) experimental data is presented for the in-cylinder flow field development of a motored four stroke spark ignition (SI) optical internal combustion (IC) engine. A high speed DPIV system was employed to quantify the velocity field development during the intake and compression stroke at an engine speed of 1500 rpm. The results map the spatial and temporal development of the in-cylinder flow field structure allowing comparison between traditional ensemble average and cycle average flow field structures. Conclusions are drawn with respect to engine flow field cyclic variations.

Fluid flow and fuel-air mixing in a motored two-dimensional Wankel rotary engine

NASA Technical Reports Server (NTRS)

Shih, T. I.-P.; Nguyen, H. L.; Stegeman, J.

1986-01-01

The implicit-factored method of Beam and Warming was employed to obtain numerical solutions to the conservation equations of mass, species, momentum, and energy to study the unsteady, multidimensional flow and mixing of fuel and air inside the combustion chambers of a two-dimensional Wankel rotary engine under motored conditions. The effects of the following engine design and operating parameters on fluid flow and fuel-air mixing during the intake and compression cycles were studied: engine speed, angle of gaseous fuel injection during compression cycle, and speed of the fuel leaving fuel injector.

Fluid flow and fuel-air mixing in a motored two-dimensional Wankel rotary engine

NASA Astrophysics Data System (ADS)

Shih, T. I.-P.; Nguyen, H. L.; Stegeman, J.

1986-06-01

The implicit-factored method of Beam and Warming was employed to obtain numerical solutions to the conservation equations of mass, species, momentum, and energy to study the unsteady, multidimensional flow and mixing of fuel and air inside the combustion chambers of a two-dimensional Wankel rotary engine under motored conditions. The effects of the following engine design and operating parameters on fluid flow and fuel-air mixing during the intake and compression cycles were studied: engine speed, angle of gaseous fuel injection during compression cycle, and speed of the fuel leaving fuel injector.

Investigation of Altitude Starting and Acceleration Characteristics of J47 Turbojet Engine

NASA Technical Reports Server (NTRS)

Golladay, Richard L; Bloomer, Harry E

1951-01-01

An investigation was conducted on an axial-flow-compressor type turbojet engine in the NACA Lewis altitude wind tunnel to determine the operational characteristics of several ignition systems, cross-fire tube configurations and fuel systems over a range of simulated flight conditions. The opposite-polarity-type spark plug provided the most satisfactory ignition. Increasing the cross-fire-tube diameter improved intercombustor flame propagation. At high windmilling speeds, accelerations to approximately 6200 rpm could be made at a preset constant throttle position. The use of a variable-area nozzle reduced acceleration time.

Flight investigation of an air-cooled plug nozzle with afterburning turbojet

NASA Technical Reports Server (NTRS)

Samanich, N. E.

1972-01-01

A convectively cooled plug nozzle, using 4 percent of the engine air as the coolant, was tested in 1967 K (3540 R) temperature exhaust gas. No significant differences in cooling characteristics existed between flight and static results. At flight speeds above Mach 1.1, nozzle performance was improved by extending the outer shroud. Increasing engine power improved nozzle efficiency considerably more at Mach 1.2 than at 0.9. The effect of nozzle pressure ratio and secondary weight flow on nozzle performance are also presented.

Aerodynamic and acoustic behavior of a YF-12 inlet at static conditions

NASA Technical Reports Server (NTRS)

Bangert, L. H.; Feltz, E. P.; Godby, L. A.; Miller, L. D.

1981-01-01

An aeroacoustic test program to determine the cause of YF-12 inlet noise suppression was performed with a YF-12 aircraft at ground static conditions. Data obtained over a wide range of engine speeds and inlet configurations are reported. Acoustic measurements were made in the far field and aerodynamic and acoustic measurements were made inside the inlet. The J-58 test engine was removed from the aircraft and tested separately with a bellmouth inlet. The far field noise level was significantly lower for the YF-12 inlet than for the bellmouth inlet at engine speeds above 5500 rpm. There was no evidence that noise suppression was caused by flow choking. Multiple pure tones were reduced and the spectral peak near the blade passing frequency disappeared in the region of the spike support struts at engine speeds between 6000 and 6600 rpm.

Backup control airstart performance on a digital electronic engine control-equipped F100-engine

NASA Technical Reports Server (NTRS)

Johnson, J. B.

1984-01-01

The air start capability of a backup control (BUC) was tested for a digital electronic engine control (DEEC) equipped F100 engine, which was installed in an F-15 aircraft. Two air start schedules were tested. Using the group 1 start schedule, based on a 40 sec timer, an air speed of 300 knots was required to ensure successful 40 and 25% BUC mode spooldown airstarts. If core rotor speed (N2) was less than 40% a stall would occur when the start bleed closed, 40 sec after initiation of the air start. All jet fuel starter (JFS) assisted air starts were successful with the group 1 start schedule. For the group 2 schedule, the time between pressurization and start bleed closure ranged between 50 sec and 72 sec. Idle rps was lower than the desired 65% for air starts at higher altitudes and lower air speeds.

Rapid deceleration mode evaluation

NASA Technical Reports Server (NTRS)

Conners, Timothy R.; Nobbs, Steven G.; Orme, John S.

1995-01-01

Aircraft with flight capability above 1.4 normally have an RPM lockup or similar feature to prevent inlet buzz that would occur at low engine airflows. This RPM lockup has the effect of holding the engine thrust level at the intermediate power (maximum non-afterburning). For aircraft such as military fighters or supersonic transports, the need exists to be able to rapidly slow from supersonic to subsonic speeds. For example, a supersonic transport that experiences a cabin decompression needs to be able to slow/descend rapidly, and this requirement may size the cabin environmental control system. For a fighter, there may be a desire to slow/descend rapidly, and while doing so to minimize fuel usage and engine exhaust temperature. Both of these needs can be aided by achieving the minimum possible overall net propulsive force. As the intermediate power thrust levels of engines increase, it becomes even more difficult to slow rapidly from supersonic speeds. Therefore, a mode of the performance seeking control (PSC) system to minimize overall propulsion system thrust has been developed and tested. The rapid deceleration mode reduces the engine airflow consistent with avoiding inlet buzz. The engine controls are trimmed to minimize the thrust produced by this reduced airflow, and moves the inlet geometry to degrade the inlet performance. As in the case of the other PSC modes, the best overall performance (in this case the least net propulsive force) requires an integrated optimization of inlet, engine, and nozzle variables. This paper presents the predicted and measured results for the supersonic minimum thrust mode, including the overall effects on aircraft deceleration.

40 CFR 87.1 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... engines. Class TF means all turbofan or turbojet aircraft engines or aircraft engines designed for... turbine engines employed for propulsion of aircraft designed to operate at supersonic flight speeds... Model means all commercial aircraft turbine engines which are of the same general series, displacement...

40 CFR 87.1 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... engines. Class TF means all turbofan or turbojet aircraft engines or aircraft engines designed for... turbine engines employed for propulsion of aircraft designed to operate at supersonic flight speeds... Model means all commercial aircraft turbine engines which are of the same general series, displacement...

40 CFR 87.1 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... engines. Class TF means all turbofan or turbojet aircraft engines or aircraft engines designed for... turbine engines employed for propulsion of aircraft designed to operate at supersonic flight speeds... Model means all commercial aircraft turbine engines which are of the same general series, displacement...

An investigation of rotor tip leakage flows in the rear-block of a multistage compressor

NASA Astrophysics Data System (ADS)

Brossman, John Richard

An effective method to improve gas turbine propulsive efficiency is to increase the bypass ratio. With fan diameter reaching a practical limit, increases in bypass ratio can be obtained from reduced core engine size. Decreasing the engine core, results in small, high pressure compressor blading, and large relative tip clearances. At general rule of 1% reduction in compressor efficiency with a 1% increase in tip clearance, a 0.66% change in SFC indicates the entire engine is sensitive to high pressure compressor tip leakage flows. Therefore, further investigations and understanding of the rotor tip leakage flows can help to improve gas turbine engine efficiency. The objectives of this research were to investigate tip leakage flows through computational modeling, examine the baseline experimental steady-stage performance, and acquire unsteady static pressure, over-the rotor to observe the tip leakage flow structure. While tip leakage flows have been investigated in the past, there have been no facilities capable of matching engine representative Reynolds number and Mach number while maintaining blade row interactions, presenting a unique and original flow field to investigate at the Purdue 3-stage axial compressor facility. To aid the design of experimental hardware and determine the influence of clearance geometry on compressor performance, a computational model of the Purdue 3-stage compressor was investigated using a steady RANS CFD analysis. A cropped rotor and casing recess design was investigated to increase the rotor tip clearance. While there were small performance differences between the geometries, the tip leakage flow field was found independent of the design therefore designing future experimental hardware around a casing recess is valid. The largest clearance with flow margin past the design point was 4% tip clearance based on the computational model. The Purdue 3-stage axial compressor facility was rebuilt and setup for high quality, detailed flow measurements during this investigation. A detailed investigation and sensitivity analysis of the inlet flow field found the influence by the inlet total temperature profile was important to performance calculations. This finding was significant and original as previous investigations have been conducted on low-speed machines where there is minimal temperature rise. The steady state performance of the baseline 1.5% tip clearance case was outlined at design speed and three off-design speeds. The leakage flow from the rear seal, the inlet flow field and a thermal boundary condition over the casing was recorded at each operating point. Stage 1 was found to be the limiting stage independent of speed. Few datasets exist on multistage compressor performance with full boundary condition definitions, especially with off-design operating points presenting this as a unique dataset for CFD comparison. The detailed unsteady pressure measurements were conducted over Rotor 1 at design and a near-stall operating condition to characterize the leakage trajectory and position. The leakage flow initial point closer to the leading edge and trajectory angle increased at the higher loading condition. The over-the-rotor static pressure field on Rotor 1 indicated similar trends between the computational model and the leakage trajectory.

Study and Sub-System Optimization of Propulsion and Drive Systems for the Large Civil TiltRotor (LCTR2) Rotorcraft

NASA Technical Reports Server (NTRS)

Robuck, Mark; Wilkerson, Joseph; Snyder, Christopher A.; Zhang, Yiyi; Maciolek, Bob

2013-01-01

In a series of study tasks conducted as a part of NASA's Fundamental Aeronautics Program, Rotary Wing Project, Boeing and Rolls-Royce explored propulsion, drive, and rotor system options for the NASA Large Civil Tilt Rotor (LCTR2) concept vehicle. The original objective of this study was to identify engine and drive system configurations to reduce rotor tip speed during cruise conditions and quantify the associated benefits. Previous NASA studies concluded that reducing rotor speed (from 650 fps hover tip speed) during cruise would reduce vehicle gross weight and fuel burn. Initially, rotor cruise speed ratios of 54% of the hover tip speed were of most interest during operation at cruise air speed of 310 ktas. Interim results were previously reported1 for cruise tip speed ratios of 100%, 77%, and 54% of the hover tip speed using engine and/or gearbox features to achieve the reduction. Technology levels from commercial off-the-shelf (COTS), through entry-in-service (EIS) dates of 2025 and 2035 were considered to assess the benefits of advanced technology on vehicle gross weight and fuel burn. This technical paper presents the final study results in terms of vehicle sizing and fuel burn as well as Operational and Support (O&S) costs. New vehicle sizing at rotor tip speed reduced to 65% of hover is presented for engine performance with an EIS 2035 fixed geometry variable speed power turbine. LCTR2 is also evaluated for missions range cases of 400, 600, 800, 1000, and 1200 nautical miles and cruise air speeds of 310, 350 and 375 ktas.

Emulation study on system characteristic of high pressure common-rail fuel injection system for marine medium-speed diesel engine

NASA Astrophysics Data System (ADS)

Wang, Qinpeng; Yang, Jianguo; Xin, Dong; He, Yuhai; Yu, Yonghua

2018-05-01

In this paper, based on the characteristic analyzing of the mechanical fuel injection system for the marine medium-speed diesel engine, a sectional high-pressure common rail fuel injection system is designed, rated condition rail pressure of which is 160MPa. The system simulation model is built and the performance of the high pressure common rail fuel injection system is analyzed, research results provide the technical foundation for the system engineering development.

Research on Correlation between Vehicle Cycle and Engine Cycle in Heavy-duty commercial vehicle

NASA Astrophysics Data System (ADS)

lin, Chen; Zhong, Wang; Shuai, Liu

2017-12-01

In order to study the correlation between vehicle cycle and engine cycle in heavy commercial vehicles, the conversion model of vehicle cycle to engine cycle is constructed based on the vehicle power system theory and shift strategy, which considers the verification on diesel truck. The results show that the model has high rationality and reliability in engine operation. In the acceleration process of high speed, the difference of model gear selection leads to the actual deviation. Compared with the drum test, the engine speed distribution obtained by the model deviates to right, which fits to the lower grade. The grade selection has high influence on the model.

Progress in Open Rotor Research: A U.S. Perspective

NASA Technical Reports Server (NTRS)

Van Zante, Dale E.

2015-01-01

In response to the 1970s oil crisis, NASA created the Advanced Turboprop Project (ATP) to mature technologies for high-speed propellers to enable large reductions in fuel burn relative to turbofan engines of that era. Both single rotation and contra-rotation concepts were designed and tested in ground based facilities as well as flight. Some novel concepts configurations that were not well publicized at the time, were proposed as part of the effort. The high-speed propeller concepts did provide fuel burn savings, albeit with some acoustics and structural challenges to overcome. When fuel prices fell, the business case for radical new engine configurations collapsed and the research emphasis returned to high bypass ducted configurations. With rising oil prices and increased environmental concerns there is renewed interest in high-speed propeller based engine architectures. Contemporary analysis tools for aerodynamics and aeroacoustics have enabled a new era of blade designs that have both high efficiency and acceptable noise characteristics. A recent series of tests in the U.S. have characterized the aerodynamic performance and noise from these modern contra-rotating propeller designs. Additionally the installation and noise shielding aspects for conventional airframes and blended wing bodies have been studied. Historical estimates of propfan performance have relied on legacy propeller performance and acoustics data. Current system studies make use of the modern propeller data with higher fidelity installation effects data to estimate the performance of a contemporary aircraft system with favorable results. This paper presents the current state of high-speed propeller open rotor research within the U.S. from an overall viewpoint of the various efforts ongoing. The current projections for the technology are presented.

SOAC - State-of-the-Art Car Engineering Tests at Department of Transportation High Speed Ground Test Center : Volume 7. Post-Repair Tests.

DOT National Transportation Integrated Search

1976-11-01

This document presents the test results from the State-of-the-Art Post-Repair Engineering Test Program conducted at the DOT High-Speed Ground Test Center, Pueblo, Colorado, from March 18th to 29th, 1974. The SOAC has been developed under UMTA's Urban...

Power of a Finite Speed Carnot Engine

ERIC Educational Resources Information Center

Agrawal, D. C.; Menon, V. J.

2009-01-01

A model of an endoreversible Carnot engine is considered where the piston moves with a constant speed "u." Expressions for the cycle time [tau] for the four branches, as well as output power, P[subscript W], are derived and the optimized root for maximum power is obtained in closed form. Our results are discussed in terms of the isothermal…

A Finite Speed Curzon-Ahlborn Engine

ERIC Educational Resources Information Center

Agrawal, D. C.

2009-01-01

Curzon and Ahlborn achieved finite power output by introducing the concept of finite rate of heat transfer in a Carnot engine. The finite power can also be achieved through a finite speed of the piston on the four branches of the Carnot cycle. The present paper combines these two approaches to study the behaviour of output power in terms of…

40 CFR Appendix II to Part 1039 - Steady-State Duty Cycles

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Steady-State Duty Cycles II Appendix... Appendix II to Part 1039—Steady-State Duty Cycles (a) The following duty cycles apply for constant-speed engines: (1) The following duty cycle applies for discrete-mode testing: D2 mode number Engine speed...

Experimental investigation on CRDI engine using butanol-biodiesel-diesel blends as fuel

NASA Astrophysics Data System (ADS)

Divakar Shetty, A. S.; Dineshkumar, L.; Koundinya, Sandeep; Mane, Swetha K.

2017-07-01

In this research work an experimental investigation of butanol-biodisel-diesel blends on combustion, performance and emission characteristics of a direct injection (DI) diesel engine is carried out. The blends are prepared at different proportions and fuel properties such as calorific value, viscosity, flash point and fire point, cloud point, pour point of butanol (B), biodiesel (B), diesel (D), biodiesel-diesel (BD) blends and butanol-biodiesel-diesel (BBD) blends are determined. The engine test is conducted at different speed and load. From the results obtained for fuel properties we can observe that the flash, fire and pour point, viscosity and density are decreasing by increasing the percentage of butanol in BBD blends. It is also observed that the performance parameters such as brake thermal efficiency (BTE) and exhaust gas temperature increases with increase in the proportion of butanol in BBD blend. However, the brake specific fuel consumption (BFSC) decreases with increase in the proportion of butanol in BBD blend. The increase of butanol in BBD blends also influence to increase on emission characteristic such as carbon monoxide (CO), hydrocarbon (HC) and oxides of nitrogen (NOx).

Regulated and unregulated emissions from a diesel engine fueled with diesel fuel blended with diethyl adipate

NASA Astrophysics Data System (ADS)

Zhu, Ruijun; Cheung, C. S.; Huang, Zuohua; Wang, Xibin

2011-04-01

Experiments were carried out on a four-cylinder direct-injection diesel engine operating on Euro V diesel fuel blended with diethyl adipate (DEA). The blended fuels contain 8.1%, 16.4%, 25% and 33.8% by volume fraction of DEA, corresponding to 3%, 6%, 9% and 12% by mass of oxygen in the blends. The engine performance and exhaust gas emissions of the different fuels were investigated at five engine loads at a steady speed of 1800 rev/min. The results indicated an increase of brake specific fuel consumption and brake thermal efficiency when the engine was fueled with the blended fuels. In comparison with diesel fuel, the blended fuels resulted in an increase in hydrocarbon (HC) and carbon monoxide (CO), but a decrease in particulate mass concentrations. The nitrogen oxides (NO x) emission experienced a slight variation among the test fuels. In regard to the unregulated gaseous emissions, formaldehyde and acetaldehyde increased, while 1,3-butadiene, ethene, ethyne, propylene and BTX (benzene, toluene and xylene) in general decreased. A diesel oxidation catalyst (DOC) was found to reduce significantly most of the investigated unregulated pollutants when the exhaust gas temperature was sufficiently high.

14 CFR 23.73 - Reference landing approach speed.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Reference landing approach speed. 23.73... Reference landing approach speed. (a) For normal, utility, and acrobatic category reciprocating engine-powered airplanes of 6,000 pounds or less maximum weight, the reference landing approach speed, VREF, must...

40 CFR 205.54-1 - Low speed sound emission test procedures.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Low speed sound emission test....54-1 Low speed sound emission test procedures. (a) Instrumentation. The following instrumentation... checked annually to verify that its output has not changed. (3) An engine-speed tachometer which is...

14 CFR 23.73 - Reference landing approach speed.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Reference landing approach speed. 23.73... Reference landing approach speed. (a) For normal, utility, and acrobatic category reciprocating engine-powered airplanes of 6,000 pounds or less maximum weight, the reference landing approach speed, VREF, must...

High speed commercial transport fuels considerations and research needs

NASA Technical Reports Server (NTRS)

Lee, C. M.; Niedzwiecki, R. W.

1989-01-01

NASA is currently evaluating the potential of incorporating High Speed Civil Transport (HSCT) aircraft in the commercial fleet in the beginning of the 21st century. NASA sponsored HSCT enabling studies currently underway with airframers and engine manufacturers, are addressing a broad range of technical, environmental, economic, and related issues. Supersonic cruise speeds for these aircraft were originally focused in the Mach 2 to 5 range. At these flight speeds, both jet fuels and liquid methane were considered potential fuel candidates. For the year 2000 to 2010, cruise Mach numbers of 2 to 3+ are projected for aircraft fuel with thermally stable liquid jet fuels. For 2015 and beyond, liquid methane fueled aircraft cruising at Mach numbers of 4+ may be viable candidates. Operation at supersonic speeds will be much more severe than those encountered at subsonic flight. One of the most critical problems is the potential deterioration of the fuel due to the high temperature environment. HSCT fuels will not only be required to provide the energy necessary for flight, but will also be subject to aerodynamic heating and, will be required to serve as the primary heat sink for cooling the engine and airframe. To define fuel problems for high speed flight, a fuels workshop was conducted at NASA Lewis Research Center. The purpose of the workshop was to gather experts on aviation fuels, airframe fuel systems, airport infrastructure, and combustion systems to discuss high speed fuel alternatives, fuel supply scenarios, increased thermal stability approaches and measurements, safety considerations, and to provide directional guidance for future R and D efforts. Subsequent follow-up studies defined airport infrastructure impacts of high speed fuel candidates. The results of these activities are summarized. In addition, an initial case study using modified in-house refinery simulation model Gordian code (1) is briefly discussed. This code can be used to simulate different types of refineries, emphasizing jet fuel production and relative cost factors.

Emission and Performance Analysis of ZrO2 And CeO2 Coated Piston Using Refined Vegetable Oils

NASA Astrophysics Data System (ADS)

Hemanandh, J.; Narayanan, K. V.; Manoj, Vemuri

2017-05-01

Increase in global warming and pollution leads to look for an alternative fuel. The aim of this paper to improve the performance and to reduce the emissions in DI diesel engine. The 80% of ZrO2 and 20% of CeO2 were mixed and coated on the piston head using plasma spray method. The B10 fuel of various refined vegetable oil methyl esters were used as fuel. The test was conducted in the 4-stroke DI diesel engine at a constant speed of 1500 rpm. The results show that the brake thermal efficiency, NOx and BSFC was increased. The CO and HC were decreased.

Active Control of Fan Noise-Feasibility Study. Volume 1; Flyover System Noise Studies

NASA Technical Reports Server (NTRS)

Kraft, Robert E.; Janardan, B. A.; Kontos, G. C.; Gliebe, P. R.

1994-01-01

A study has been completed to examine the potential reduction of aircraft flyover noise by the method of active noise control (ANC). It is assumed that the ANC system will be designed such that it cancels discrete tones radiating from the engine fan inlet or fan exhaust duct. Thus, without considering the engineering details of the ANC system design, tone levels are arbitrarily removed from the engine component noise spectrum and the flyover noise EPNL levels are compared with and without the presence of tones. The study was conducted for a range of engine cycles, corresponding to fan pressure ratios from 1.3 to 1.75. The major conclusions that can be drawn are that, for a fan pressure ratio of 1.75, ANC of tones gives about the same suppression as acoustic treatment without ANC, and for a fan pressure ratio of 1.45, ANC appears to offer less effectiveness than passive treatment. Additionally, ANC appears to be more effective at sideline and cutback conditions than at approach. Overall EPNL suppressions due to tone removal range from about 1 to 3 dB at takeoff engine speeds and from 1 to 5 db at approach speeds. Studies of economic impact of the installation of an ANC system for the four engine cases indicate increases of DOC ranging from 1 to 2 percent, favoring the lower fan pressure ratio engines. Further study is needed to confirm the results by examining additional engine data, particularly at low fan pressure ratios, and studying the details of the current results to obtain a more complete understanding. Further studies should also include determining the effects of combining passive and active treatment.

Hot piston ring tests

NASA Technical Reports Server (NTRS)

Allen, David J.; Tomazic, William A.

1987-01-01

As part of the DOE/NASA Automotive Stirling Engine Project, tests were made at NASA Lewis Research Center to determine whether appendix gap losses could be reduced and Stirling engine performance increased by installing an additional piston ring near the top of each piston dome. An MTI-designed upgraded Mod I Automotive Stirling Engine was used. Unlike the conventional rings at the bottom of the piston, these hot rings operated in a high temperature environment (700 C). They were made of a high temperature alloy (Stellite 6B) and a high temperature solid lubricant coating (NASA Lewis-developed PS-200) was applied to the cylinder walls. Engine tests were run at 5, 10, and 15 MPa operating pressure over a range of operating speeds. Tests were run both with hot rings and without to provide a baseline for comparison. Minimum data to assess the potential of both the hot rings and high temperature low friction coating was obtained. Results indicated a slight increase in power and efficiency, an increase over and above the friction loss introduced by the hot rings. Seal leakage measurements showed a significant reduction. Wear on both rings and coating was low.

Integrated Flight-propulsion Control Concepts for Supersonic Transport Airplanes

NASA Technical Reports Server (NTRS)

Burcham, Frank W., Jr.; Gilyard, Glenn B.; Gelhausen, Paul A.

1990-01-01

Integration of propulsion and flight control systems will provide significant performance improvements for supersonic transport airplanes. Increased engine thrust and reduced fuel consumption can be obtained by controlling engine stall margin as a function of flight and engine operating conditions. Improved inlet pressure recovery and decreased inlet drag can result from inlet control system integration. Using propulsion system forces and moments to augment the flight control system and airplane stability can reduce the flight control surface and tail size, weight, and drag. Special control modes may also be desirable for minimizing community noise and for emergency procedures. The overall impact of integrated controls on the takeoff gross weight for a generic high speed civil transport is presented.

Research and Engineering Operation, Irradiation Processing Department monthly record report, May 1965

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

Ambrose, T.W.

1965-06-04

Process and development activities reported include: depleted uranium irradiations, thoria irradiation, and hot die sizing. Reactor engineering activities include: brittle fracture of 190-C tanks, increased graphite temperature limits for the F reactor, VSR channel caulking, K reactor downcomer flow, zircaloy hydriding, and ribbed zircaloy process tubes. Reactor physics activities include: thoria irradiations, E-D irradiations, boiling protection with the high speed scanner, and in-core flux monitoring. Radiological engineering activities include: radiation control, classification, radiation occurrences, effluent activity data, and well car shielding. Process standards are listed, along with audits, and fuel failure experience. Operational physics and process physics studies are presented.more » Lastly, testing activities are detailed.« less

Managing MDO Software Development Projects

NASA Technical Reports Server (NTRS)

Townsend, J. C.; Salas, A. O.

2002-01-01

Over the past decade, the NASA Langley Research Center developed a series of 'grand challenge' applications demonstrating the use of parallel and distributed computation and multidisciplinary design optimization. All but the last of these applications were focused on the high-speed civil transport vehicle; the final application focused on reusable launch vehicles. Teams of discipline experts developed these multidisciplinary applications by integrating legacy engineering analysis codes. As teams became larger and the application development became more complex with increasing levels of fidelity and numbers of disciplines, the need for applying software engineering practices became evident. This paper briefly introduces the application projects and then describes the approaches taken in project management and software engineering for each project; lessons learned are highlighted.

Evaluation of scavenging in two-stroke-cycle engines

NASA Technical Reports Server (NTRS)

Venediger, Herbert J

1934-01-01

The viewpoints are discussed, according to which the scavenging of two-stroke-cycle engines can be evaluated, and the relations between scavenging pressure and the quantity of the scavenging medium required, as also between the scavenging pressure and the revolution speed, are developed. It is further shown that the power increase is limited by the scavenging process, so that further researches are desirable for qualitative improvement. These results lead to several conclusions regarding the propulsion of motor vehicles by the two-stroke-cycle engines. Lastly, attention is called to the fundamental defect of the two-dimensional treatment of the scavenging process and to the consequent distinction between the two-dimensional and three-dimensional scavenging-type efficiency.

14 CFR 33.63 - Vibration.

Code of Federal Regulations, 2011 CFR

2011-01-01

... and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.63 Vibration. Each engine... range of rotational speeds and power/thrust, without inducing excessive stress in any engine part...

14 CFR 33.63 - Vibration.

Code of Federal Regulations, 2010 CFR

2010-01-01

... and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.63 Vibration. Each engine... range of rotational speeds and power/thrust, without inducing excessive stress in any engine part...

Application of several variable-valve-timing concepts to an LHR engine

NASA Technical Reports Server (NTRS)

Morel, T.; Keribar, R.; Sawlivala, M.; Hakim, N.

1987-01-01

The paper discusses advantages provided by electronically controlled hydraulically activated valves (ECVs) when applied to low heat rejection (LHR) engines. The ECV concept provides additional engine control flexibility by allowing for a variable valve timing as a function of speed and load, or for a given transient condition. The results of a study carried out to assess the benefits that this flexibility can offer to an LHR engine indicated that, when judged on the benefits to BSFC, volumetric efficiency, and peak firing pressure, ECVs would provide only modest benefits in comparison to conventional valve profiles. It is noted, however, that once installed on the engine, the ECVs would permit a whole range of certain more sophisticated variable valve timing strategies not otherwise possible, such as high compression cranking, engine braking, cylinder cutouts, and volumetric efficiency timing with engine speed.

Simulations of the Fuel Economy and Emissions of Hybrid Transit Buses over Planned Local Routes

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

Gao, Zhiming; LaClair, Tim J; Daw, C Stuart

2014-01-01

We present simulated fuel economy and emissions city transit buses powered by conventional diesel engines and diesel-hybrid electric powertrains of varying size. Six representative city drive cycles were included in the study. In addition, we included previously published aftertreatment device models for control of CO, HC, NOx, and particulate matter (PM) emissions. Our results reveal that bus hybridization can significantly enhance fuel economy by reducing engine idling time, reducing demands for accessory loads, exploiting regenerative braking, and shifting engine operation to speeds and loads with higher fuel efficiency. Increased hybridization also tends to monotonically reduce engine-out emissions, but trends inmore » the tailpipe (post-aftertreatment) emissions involve more complex interactions that significantly depend on motor size and drive cycle details.« less

ISGV Self-rectifying Turbine Design For Thermoacoustic Application

NASA Astrophysics Data System (ADS)

Sammak, Shervin; Asghary, Maryam; Ghorbanian, Kaveh

2014-11-01

Thermoacoustic engines produce the acoustic power from wasted heat and then electricity can be generated from acoustic power. Utilizing self-rectifying turbine after a thermoacoustic engine allows for deploying standard generators with high enough rotational speed that remarkably reduce abrasion, size and cost and significantly increase efficiency and controllability in comparison with linear alternators. In this paper, by evaluating all different type of self-rectifying turbine, impulse turbine with self-piched controlled (ISGV) is chosen as the most appropriate type for this application. This kind of turbine is designed in detail for a popular engine, thermoacoustic stirling heat engine (TASHE). In order to validate the design, a full scale size of designed turbine is modeled in ANSYS CFX. As a result, optimum power and efficiency gained based on numerical data.

Conversion and control of an all-terrain vehicle for use as an autonomous mobile robot

NASA Astrophysics Data System (ADS)

Jacob, John S.; Gunderson, Robert W.; Fullmer, R. R.

1998-08-01

A systematic approach to ground vehicle automation is presented, combining low-level controls, trajectory generation and closed-loop path correction in an integrated system. Development of cooperative robotics for precision agriculture at Utah State University required the automation of a full-scale motorized vehicle. The Triton Predator 8- wheeled skid-steering all-terrain vehicle was selected for the project based on its ability to maneuver precisely and the simplicity of controlling the hydrostatic drivetrain. Low-level control was achieved by fitting an actuator on the engine throttle, actuators for the left and right drive controls, encoders on the left and right drive shafts to measure wheel speeds, and a signal pick-off on the alternator for measuring engine speed. Closed loop control maintains a desired engine speed and tracks left and right wheel speeds commands. A trajectory generator produces the wheel speed commands needed to steer the vehicle through a predetermined set of map coordinates. A planar trajectory through the points is computed by fitting a 2D cubic spline over each path segment while enforcing initial and final orientation constraints at segment endpoints. Acceleration and velocity profiles are computed for each trajectory segment, with the velocity over each segment dependent on turning radius. Left and right wheel speed setpoints are obtained by combining velocity and path curvature for each low-level timestep. The path correction algorithm uses GPS position and compass orientation information to adjust the wheel speed setpoints according to the 'crosstrack' and 'downtrack' errors and heading error. Nonlinear models of the engine and the skid-steering vehicle/ground interaction were developed for testing the integrated system in simulation. These test lead to several key design improvements which assisted final implementation on the vehicle.

Aerodynamic characteristics of a six-jet V/STOL configuration with four swing-out lift jets in the transition speed range

NASA Technical Reports Server (NTRS)

Carter, A. W.

1970-01-01

A wind-tunnel investigation has been made of the longitudinal aerodynamic characteristics and jet-interference effects of a model of a jet V/STOL variable-sweep fighter airplane that employs four direct-lift engines which swing out from the fuselage and two lift-cruise engines located in the rear part of the fuselage. Data were obtained with two wing areas for various forward speeds and power conditions in the transition speed range. The data are presented without analysis or discussion.

46 CFR 121.620 - Propulsion engine control systems.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 4 2011-10-01 2011-10-01 false Propulsion engine control systems. 121.620 Section 121... Propulsion engine control systems. (a) A vessel must have two independent means of controlling each propulsion engine. Control must be provided for the engine speed, direction of shaft rotation, and engine...

46 CFR 121.620 - Propulsion engine control systems.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 4 2012-10-01 2012-10-01 false Propulsion engine control systems. 121.620 Section 121... Propulsion engine control systems. (a) A vessel must have two independent means of controlling each propulsion engine. Control must be provided for the engine speed, direction of shaft rotation, and engine...

46 CFR 121.620 - Propulsion engine control systems.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 4 2014-10-01 2014-10-01 false Propulsion engine control systems. 121.620 Section 121... Propulsion engine control systems. (a) A vessel must have two independent means of controlling each propulsion engine. Control must be provided for the engine speed, direction of shaft rotation, and engine...

46 CFR 121.620 - Propulsion engine control systems.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Propulsion engine control systems. 121.620 Section 121... Propulsion engine control systems. (a) A vessel must have two independent means of controlling each propulsion engine. Control must be provided for the engine speed, direction of shaft rotation, and engine...

40 CFR 89.410 - Engine test cycle.

Code of Federal Regulations, 2011 CFR

2011-07-01

..., except constant speed engines, engines rated under 19 kW, and propulsion marine diesel engines. (2) The 5... this subpart shall be used for propulsion marine diesel engines. (5) Notwithstanding the provisions of... rated under 19 kW; or (B) Propulsion marine diesel engines, provided the propulsion marine diesel...

46 CFR 121.620 - Propulsion engine control systems.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 4 2013-10-01 2013-10-01 false Propulsion engine control systems. 121.620 Section 121... Propulsion engine control systems. (a) A vessel must have two independent means of controlling each propulsion engine. Control must be provided for the engine speed, direction of shaft rotation, and engine...

Development of Predictive Energy Management Strategies for Hybrid Electric Vehicles

NASA Astrophysics Data System (ADS)

Baker, David

Studies have shown that obtaining and utilizing information about the future state of vehicles can improve vehicle fuel economy (FE). However, there has been a lack of research into the impact of real-world prediction error on FE improvements, and whether near-term technologies can be utilized to improve FE. This study seeks to research the effect of prediction error on FE. First, a speed prediction method is developed, and trained with real-world driving data gathered only from the subject vehicle (a local data collection method). This speed prediction method informs a predictive powertrain controller to determine the optimal engine operation for various prediction durations. The optimal engine operation is input into a high-fidelity model of the FE of a Toyota Prius. A tradeoff analysis between prediction duration and prediction fidelity was completed to determine what duration of prediction resulted in the largest FE improvement. Results demonstrate that 60-90 second predictions resulted in the highest FE improvement over the baseline, achieving up to a 4.8% FE increase. A second speed prediction method utilizing simulated vehicle-to-vehicle (V2V) communication was developed to understand if incorporating near-term technologies could be utilized to further improve prediction fidelity. This prediction method produced lower variation in speed prediction error, and was able to realize a larger FE improvement over the local prediction method for longer prediction durations, achieving up to 6% FE improvement. This study concludes that speed prediction and prediction-informed optimal vehicle energy management can produce FE improvements with real-world prediction error and drive cycle variability, as up to 85% of the FE benefit of perfect speed prediction was achieved with the proposed prediction methods.

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

Hessell, Steven M.; Morris, Robert L.; McGrogan, Sean W.

A powertrain including an engine and torque machines is configured to transfer torque through a multi-mode transmission to an output member. A method for controlling the powertrain includes employing a closed-loop speed control system to control torque commands for the torque machines in response to a desired input speed. Upon approaching a power limit of a power storage device transferring power to the torque machines, power limited torque commands are determined for the torque machines in response to the power limit and the closed-loop speed control system is employed to determine an engine torque command in response to the desiredmore » input speed and the power limited torque commands for the torque machines.« less

A method of calculating the performance of controllable propellers with sample computations

NASA Technical Reports Server (NTRS)

Hartman, Edwin P

1934-01-01

This paper contains a series of calculations showing how the performance of controllable propellers may be derived from data on fixed-pitch propellers given in N.A.C.A. Technical Report No. 350, or from similar data. Sample calculations are given which compare the performance of airplanes with fixed-pitch and with controllable propellers. The gain in performance with controllable propellers is shown to be largely due to the increased power available, rather than to an increase in efficiency. Controllable propellers are of particular advantage when used with geared and with supercharged engines. A controllable propeller reduces the take-off run, increases the rate of climb and the ceiling, but does not increase the high speed, except when operating above the design altitude of the previously used fixed-pitch propeller or when that propeller was designed for other than high speed.

Evaluation of an Outer Loop Retrofit Architecture for Intelligent Turbofan Engine Thrust Control

NASA Technical Reports Server (NTRS)

Litt, Jonathan S.; Sowers, T. Shane

2006-01-01

The thrust control capability of a retrofit architecture for intelligent turbofan engine control and diagnostics is evaluated. The focus of the study is on the portion of the hierarchical architecture that performs thrust estimation and outer loop thrust control. The inner loop controls fan speed so the outer loop automatically adjusts the engine's fan speed command to maintain thrust at the desired level, based on pilot input, even as the engine deteriorates with use. The thrust estimation accuracy is assessed under nominal and deteriorated conditions at multiple operating points, and the closed loop thrust control performance is studied, all in a complex real-time nonlinear turbofan engine simulation test bed. The estimation capability, thrust response, and robustness to uncertainty in the form of engine degradation are evaluated.

Adaptive Gas Turbine Engine Control for Deterioration Compensation Due to Aging

NASA Technical Reports Server (NTRS)

Litt, Jonathan S.; Parker, Khary I.; Chatterjee, Santanu

2003-01-01

This paper presents an ad hoc adaptive, multivariable controller tuning rule that compensates for a thrust response variation in an engine whose performance has been degraded though use and wear. The upset appears when a large throttle transient is performed such that the engine controller switches from low-speed to high-speed mode. A relationship was observed between the level of engine degradation and the overshoot in engine temperature ratio, which was determined to cause the thrust response variation. This relationship was used to adapt the controller. The method is shown to work very well up to the operability limits of the engine. Additionally, since the level of degradation can be estimated from sensor data, it would be feasible to implement the adaptive control algorithm on-line.

Tornado Intensity Estimated from Damage Path Dimensions

PubMed Central

Elsner, James B.; Jagger, Thomas H.; Elsner, Ian J.

2014-01-01

The Newcastle/Moore and El Reno tornadoes of May 2013 are recent reminders of the destructive power of tornadoes. A direct estimate of a tornado's power is difficult and dangerous to get. An indirect estimate on a categorical scale is available from a post-storm survery of the damage. Wind speed bounds are attached to the scale, but the scale is not adequate for analyzing trends in tornado intensity separate from trends in tornado frequency. Here tornado intensity on a continuum is estimated from damage path length and width, which are measured on continuous scales and correlated to the EF rating. The wind speeds on the EF scale are treated as interval censored data and regressed onto the path dimensions and fatalities. The regression model indicates a 25% increase in expected intensity over a threshold intensity of 29 m s−1 for a 100 km increase in path length and a 17% increase in expected intensity for a one km increase in path width. The model shows a 43% increase in the expected intensity when fatalities are observed controlling for path dimensions. The estimated wind speeds correlate at a level of .77 (.34, .93) [95% confidence interval] with a small sample of wind speeds estimated independently from a doppler radar calibration. The estimated wind speeds allow analyses to be done on the tornado database that are not possible with the categorical scale. The modeled intensities can be used in climatology and in environmental and engineering applications. Research is needed to understand the upward trends in path length and width. PMID:25229242

Tornado intensity estimated from damage path dimensions.

PubMed

Elsner, James B; Jagger, Thomas H; Elsner, Ian J

2014-01-01

The Newcastle/Moore and El Reno tornadoes of May 2013 are recent reminders of the destructive power of tornadoes. A direct estimate of a tornado's power is difficult and dangerous to get. An indirect estimate on a categorical scale is available from a post-storm survery of the damage. Wind speed bounds are attached to the scale, but the scale is not adequate for analyzing trends in tornado intensity separate from trends in tornado frequency. Here tornado intensity on a continuum is estimated from damage path length and width, which are measured on continuous scales and correlated to the EF rating. The wind speeds on the EF scale are treated as interval censored data and regressed onto the path dimensions and fatalities. The regression model indicates a 25% increase in expected intensity over a threshold intensity of 29 m s(-1) for a 100 km increase in path length and a 17% increase in expected intensity for a one km increase in path width. The model shows a 43% increase in the expected intensity when fatalities are observed controlling for path dimensions. The estimated wind speeds correlate at a level of .77 (.34, .93) [95% confidence interval] with a small sample of wind speeds estimated independently from a doppler radar calibration. The estimated wind speeds allow analyses to be done on the tornado database that are not possible with the categorical scale. The modeled intensities can be used in climatology and in environmental and engineering applications. Research is needed to understand the upward trends in path length and width.

Effect of boat noise and angling on lake fish behaviour.

PubMed

Jacobsen, L; Baktoft, H; Jepsen, N; Aarestrup, K; Berg, S; Skov, C

2014-06-01

The effects of disturbances from recreational activities on the swimming speed and habitat use of roach Rutilus rutilus, perch Perca fluviatilis and pike Esox lucius were explored. Disturbances were applied for 4 h as (1) boating in short intervals with a small outboard internal combustion engine or (2) boating in short intervals combined with angling with artificial lures between engine runs. The response of the fish species was evaluated by high-resolution tracking using an automatic acoustic telemetry system and transmitters with sub-minute burst rates. Rutilus rutilus swimming speed was significantly higher during disturbances [both (1) and (2)] with an immediate reaction shortly after the engine started. Perca fluviatilis displayed increased swimming activity during the first hour of disturbance but not during the following hours. Swimming activity of E. lucius was not significantly different between disturbance periods and the same periods on days without disturbance (control). Rutilus rutilus increased their use of the central part of the lake during disturbances, whereas no habitat change was observed in P. fluviatilis and E. lucius. No difference in fish response was detected between the two types of disturbances (boating with and without angling), indicating that boating was the primary source of disturbance. This study highlights species-specific responses to recreational boating and may have implications for management of human recreational activities in lakes. © 2014 The Fisheries Society of the British Isles.

Study of advanced rotary combustion engines for commuter aircraft

NASA Technical Reports Server (NTRS)

Berkowitz, M.; Jones, C.; Myers, D.

1983-01-01

Performance, weight, size, and maintenance data for advanced rotary aircraft engines suitable for comparative commuter aircraft system evaluation studies of alternate engine candidates are provided. These are turbocharged, turbocompounded, direct injected, stratified charge rotary engines. Hypothetical engines were defined (an RC4-74 at 895 kW and an RC6-87 at 1490 kW) based on the technologies and design approaches used in the highly advanced engine of a study of advanced general aviation rotary engines. The data covers the size range of shaft power from 597 kW (800 hp) to 1865 kW (2500 hp) and is in the form of drawings, tables, curves and written text. These include data on internal geometry and configuration, installation information, turbocharging and turbocompounding arrangements, design features and technologies, engine cooling, fuels, scaling for weight size BSFC and heat rejection for varying horsepower, engine operating and performance data, and TBO and maintenance requirements. The basic combustion system was developed and demonstrated; however the projected power densities and performance efficiencies require increases in engine internal pressures, thermal loading, and rotative speed.

An investigation of the use of discharge valves and an intake control for improving the performance of N.A.C.A. Roots type supercharger

NASA Technical Reports Server (NTRS)

Schey, Oscar W; Wilson, Ernest E

1929-01-01

This report presents the results of an analytical investigation on the practicability of using mechanically operated discharge valves in conjunction with a manually operated intake control for improving the performance of N. A. C. A. Roots type superchargers. These valves, which may be either of the oscillating or rotating type, are placed in the discharge opening of the supercharger and are so shaped and synchronized with the supercharger impellers that they do not open until the air has been compressed to the delivery pressure. The intake control limits the quantity of air compressed to engine requirements by permitting the excess air to escape from the compression chamber before compression begins. The percentage power saving and the actual horsepower saved were computed for altitudes from 0 to 20,000 feet. These computations are based on the pressure-volume cards for the conventional and the modified roots type superchargers and on the results of laboratory tests of the conventional type. The use of discharge valves shows a power saving of approximately 26 per cent at a critical altitude of 20,000 feet. In addition, these valves reduce the amplitude of the discharge pulsations and increase the volumetric efficiency. With slow-speed roots blowers operating at high-pressure differences even better results would be expected. For aircraft engine superchargers operating at high speeds these discharge valves increase the performance as above, but have the disadvantages of increasing the weight and of adding a high-speed mechanism to a simple machine. (author)

Sampling optimization for high-speed weigh-in-motion measurements using in-pavement strain-based sensors

NASA Astrophysics Data System (ADS)

Zhang, Zhiming; Huang, Ying; Bridgelall, Raj; Palek, Leonard; Strommen, Robert

2015-06-01

Weigh-in-motion (WIM) measurement has been widely used for weight enforcement, pavement design, freight management, and intelligent transportation systems to monitor traffic in real-time. However, to use such sensors effectively, vehicles must exit the traffic stream and slow down to match their current capabilities. Hence, agencies need devices with higher vehicle passing speed capabilities to enable continuous weight measurements at mainline speeds. The current practices for data acquisition at such high speeds are fragmented. Deployment configurations and settings depend mainly on the experiences of operation engineers. To assure adequate data, most practitioners use very high frequency measurements that result in redundant samples, thereby diminishing the potential for real-time processing. The larger data memory requirements from higher sample rates also increase storage and processing costs. The field lacks a sampling design or standard to guide appropriate data acquisition of high-speed WIM measurements. This study develops the appropriate sample rate requirements as a function of the vehicle speed. Simulations and field experiments validate the methods developed. The results will serve as guidelines for future high-speed WIM measurements using in-pavement strain-based sensors.

Algorithms and Object-Oriented Software for Distributed Physics-Based Modeling

NASA Technical Reports Server (NTRS)

Kenton, Marc A.

2001-01-01

The project seeks to develop methods to more efficiently simulate aerospace vehicles. The goals are to reduce model development time, increase accuracy (e.g.,by allowing the integration of multidisciplinary models), facilitate collaboration by geographically- distributed groups of engineers, support uncertainty analysis and optimization, reduce hardware costs, and increase execution speeds. These problems are the subject of considerable contemporary research (e.g., Biedron et al. 1999; Heath and Dick, 2000).

14 CFR 34.1 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-01-01

... series, displacement, and design characteristics and are approved under the same type certificate... engines. Class TF means all turbofan or turbojet aircraft engines or aircraft engines designed for... turbine engines employed for propulsion of aircraft designed to operate at supersonic flight speeds...

14 CFR 34.1 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-01-01

... series, displacement, and design characteristics and are approved under the same type certificate... engines. Class TF means all turbofan or turbojet aircraft engines or aircraft engines designed for... turbine engines employed for propulsion of aircraft designed to operate at supersonic flight speeds...

Large-scale culture of a megakaryocytic progenitor cell line with a single-use bioreactor system.

PubMed

Nurhayati, Retno Wahyu; Ojima, Yoshihiro; Dohda, Takeaki; Kino-Oka, Masahiro

2018-03-01

The increasing application of regenerative medicine has generated a growing demand for stem cells and their derivatives. Single-use bioreactors offer an attractive platform for stem cell expansion owing to their scalability for large-scale production and feasibility of meeting clinical-grade standards. The current work evaluated the capacity of a single-use bioreactor system (1 L working volume) for expanding Meg01 cells, a megakaryocytic (MK) progenitor cell line. Oxygen supply was provided by surface aeration to minimize foaming and orbital shaking was used to promote oxygen transfer. Oxygen transfer rates (k L a) of shaking speeds 50, 100, and 125 rpm were estimated to be 0.39, 1.12, and 10.45 h -1 , respectively. Shaking speed was a critical factor for optimizing cell growth. At 50 rpm, Meg01 cells exhibited restricted growth due to insufficient mixing. A negative effect occurred when the shaking speed was increased to 125 rpm, likely caused by high hydrodynamic shear stress. The bioreactor culture achieved the highest growth profile when shaken at 100 rpm, achieving a total expansion rate up to 5.7-fold with a total cell number of 1.2 ± 0.2 × 10 9 cells L -1 . In addition, cells expanded using the bioreactor system could maintain their potency to differentiate following the MK lineage, as analyzed from specific surface protein and morphological similarity with the cells grown in the conventional culturing system. Our study reports the impact of operational variables such as shaking speed for growth profile and MK differentiation potential of a progenitor cell line in a single-use bioreactor. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:362-369, 2018. © 2017 American Institute of Chemical Engineers.

Homophily and the speed of social mobilization: the effect of acquired and ascribed traits.

PubMed

Alstott, Jeff; Madnick, Stuart; Velu, Chander

2014-01-01

Large-scale mobilization of individuals across social networks is becoming increasingly prevalent in society. However, little is known about what affects the speed of social mobilization. Here we use a framed field experiment to identify and measure properties of individuals and their relationships that predict mobilization speed. We ran a global social mobilization contest and recorded personal traits of the participants and those they recruited. We studied the effects of ascribed traits (gender, age) and acquired traits (geography, and information source) on the speed of mobilization. We found that homophily, a preference for interacting with other individuals with similar traits, had a mixed role in social mobilization. Homophily was present for acquired traits, in which mobilization speed was faster when the recuiter and recruit had the same trait compared to different traits. In contrast, we did not find support for homophily for the ascribed traits. Instead, those traits had other, non-homophily effects: Females mobilized other females faster than males mobilized other males. Younger recruiters mobilized others faster, and older recruits mobilized slower. Recruits also mobilized faster when they first heard about the contest directly from the contest organization, and decreased in speed when hearing from less personal source types (e.g. family vs. media). These findings show that social mobilization includes dynamics that are unlike other, more passive forms of social activity propagation. These findings suggest relevant factors for engineering social mobilization tasks for increased speed.

Modifications to Marshall's Annular Seal Test (MAST) Rig and Facility for Improved Rotordynamic Coefficient Testing of Annular Seals and Fluid Film Bearings

NASA Technical Reports Server (NTRS)

Darden, J. M.; Earhart, E. M.

2011-01-01

The limits of rotordynamic stability continue to be pushed by the high power densities and rotational speeds of modern rocket engine turbomachinery. Destabilizing forces increase dramatically with rotor speed. Rotordynamic stability is lost when these destabilizing forces overwhelm the stabilizing forces. The vibration from the unstable rotor grows until it is limited by some nonlinearity. For example, a rolling element bearing with a stiffness characteristic that increases with deflection may limit the vibration amplitude. The loads and deflections resulting from this limit cycle vibration (LCV) can lead to bearing and seal damage which promotes ever increasing levels of subsynchronous vibration. Engineers combat LCV by introducing rotordynamic elements that generate increased stabilizing forces and reduced destabilizing forces. For example, replacing a labyrinth seal with a damping seal results in substantial increases in the damping and stiffness rotordynamic coefficients. Adding a swirl brake to the damping seal greatly reduces the destabilizing cross-coupled forces generated by the damping seal for even further increases in the stabilizing capacity. Marshall?s Annular Seal Test (MAST) rig is designed to experimentally measure the stabilizing capacity of new annular seal designs. The rig has been moved to a new facility and outfitted with a new slave bearing to allow increased test durations and to enable the testing of fluid film bearings. The purpose of this paper is to describe the new facility and the new bearing arrangement. Several novel seal and bearing designs will also be discussed.

Field testing advanced geothermal turbodrill (AGT). Phase 1 final report

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

Maurer, W.C.; Cohen, J.H.

1999-06-01

Maurer Engineering developed special high-temperature geothermal turbodrills for LANL in the 1970s to overcome motor temperature limitations. These turbodrills were used to drill the directional portions of LANL`s Hot Dry Rock Geothermal Wells at Fenton Hill, New Mexico. The Hot Dry Rock concept is to drill parallel inclined wells (35-degree inclination), hydraulically fracture between these wells, and then circulate cold water down one well and through the fractures and produce hot water out of the second well. At the time LANL drilled the Fenton Hill wells, the LANL turbodrill was the only motor in the world that would drill atmore » the high temperatures encountered in these wells. It was difficult to operate the turbodrills continuously at low speed due to the low torque output of the LANL turbodrills. The turbodrills would stall frequently and could only be restarted by lifting the bit off bottom. This allowed the bit to rotate at very high speeds, and as a result, there was excessive wear in the bearings and on the gauge of insert roller bits due to these high rotary speeds. In 1998, Maurer Engineering developed an Advanced Geothermal Turbodrill (AGT) for the National Advanced Drilling and Excavation Technology (NADET) at MIT by adding a planetary speed reducer to the LANL turbodrill to increase its torque and reduce its rotary speed. Drilling tests were conducted with the AGT using 12 1/2-inch insert roller bits in Texas Pink Granite. The drilling tests were very successful, with the AGT drilling 94 ft/hr in Texas Pink Granite compared to 45 ft/hr with the LANL turbodrill and 42 ft/hr with a rotary drill. Field tests are currently being planned in Mexico and in geothermal wells in California to demonstrate the ability of the AGT to increase drilling rates and reduce drilling costs.« less

Preliminary Results of an Altitude-Wind-Tunnel Investigation of an Axial-Flow Gas Turbine-Propeller Engine. 4; Compressor and Turbine Performance Characteristics

NASA Technical Reports Server (NTRS)

Wallner, Lewis E.; Saari, Martin J.

1948-01-01

As part of an investigation of the performance and operational characteristics of the axial-flow gas turbine-propeller engine, conducted in the Cleveland altitude wind tunnel, the performance characteristics of the compressor and the turbine were obtained. The data presented were obtained at a compressor-inlet ram-pressure ratio of 1.00 for altitudes from 5000 to 35,000 feet, engine speeds from 8000 to 13,000 rpm, and turbine-inlet temperatures from 1400 to 2100 R. The highest compressor pressure ratio obtained was 6.15 at a corrected air flow of 23.7 pounds per second and a corrected turbine-inlet temperature of 2475 R. Peak adiabatic compressor efficiencies of about 77 percent were obtained near the value of corrected air flow corresponding to a corrected engine speed of 13,000 rpm. This maximum efficiency may be somewhat low, however, because of dirt accumulations on the compressor blades. A maximum adiabatic turbine efficiency of 81.5 percent was obtained at rated engine speed for all altitudes and turbine-inlet temperatures investigated.

Preliminary Results of an Altitude-Wind-Tunnel Investigation of a TG-100A Gas Turbine-Propeller Engine. 4; Compressor and Turbine Performance Characteristics

NASA Technical Reports Server (NTRS)

Wallner, Lewis E.; Saari, Martin J.

1947-01-01

As part of an investigation of the performance and operational characteristics of the TG-100A gas turbine-propeller engine, conducted in the Cleveland altitude wind tunnel, the performance characteristics of the compressor and the turbine were obtained. The data presented were obtained at a compressor-inlet ram-pressure ratio of 1.00 for altitudes from 5000 to 35,000 feet, engine speeds from 8000 to 13,000 rpm, and turbine-inlet temperatures from 1400 to 2100R. The highest compressor pressure ratio was 6.15 at a corrected air flow of 23.7 pounds per second and a corrected turbine-inlet temperature of 2475R. Peak adiabatic compressor efficiencies of about 77 percent were obtained near the value of corrected air flow corresponding to a corrected engine speed of 13,000 rpm. This maximum efficiency may be somewhat low, however, because of dirt accumulations on the compressor blades. A maximum adiabatic turbine efficiency of 81.5 percent was obtained at rated engine speed for all altitudes and turbine-inlet temperatures investigated.

Aerodynamic design optimization of a fuel efficient high-performance, single-engine, business airplane

NASA Technical Reports Server (NTRS)

Holmes, B. J.

1980-01-01

A design study has been conducted to optimize a single-engine airplane for a high-performance cruise mission. The mission analyzed included a cruise speed of about 300 knots, a cruise range of about 1300 nautical miles, and a six-passenger payload (5340 N (1200 lb)). The purpose of the study is to investigate the combinations of wing design, engine, and operating altitude required for the mission. The results show that these mission performance characteristics can be achieved with fuel efficiencies competitive with present-day high-performance, single- and twin-engine, business airplanes. It is noted that relaxation of the present Federal Aviation Regulation, Part 23, stall-speed requirement for single-engine airplanes facilitates the optimization of the airplane for fuel efficiency.

Improved methods for fan sound field determination

NASA Technical Reports Server (NTRS)

Cicon, D. E.; Sofrin, T. G.; Mathews, D. C.

1981-01-01

Several methods for determining acoustic mode structure in aircraft turbofan engines using wall microphone data were studied. A method for reducing data was devised and implemented which makes the definition of discrete coherent sound fields measured in the presence of engine speed fluctuation more accurate. For the analytical methods, algorithms were developed to define the dominant circumferential modes from full and partial circumferential arrays of microphones. Axial arrays were explored to define mode structure as a function of cutoff ratio, and the use of data taken at several constant speeds was also evaluated in an attempt to reduce instrumentation requirements. Sensitivities of the various methods to microphone density, array size and measurement error were evaluated and results of these studies showed these new methods to be impractical. The data reduction method used to reduce the effects of engine speed variation consisted of an electronic circuit which windowed the data so that signal enhancement could occur only when the speed was within a narrow range.

Shrubs as ecosystem engineers across an environmental gradient: effects on species richness and exotic plant invasion.

PubMed

Kleinhesselink, Andrew R; Magnoli, Susan M; Cushman, J Hall

2014-08-01

Ecosystem-engineering plants modify the physical environment and can increase species diversity and exotic species invasion. At the individual level, the effects of ecosystem engineers on other plants often become more positive in stressful environments. In this study, we investigated whether the community-level effects of ecosystem engineers also become stronger in more stressful environments. Using comparative and experimental approaches, we assessed the ability of a native shrub (Ericameria ericoides) to act as an ecosystem engineer across a stress gradient in a coastal dune in northern California, USA. We found increased coarse organic matter and lower wind speeds within shrub patches. Growth of a dominant invasive grass (Bromus diandrus) was facilitated both by aboveground shrub biomass and by growing in soil taken from shrub patches. Experimental removal of shrubs negatively affected species most associated with shrubs and positively affected species most often found outside of shrubs. Counter to the stress-gradient hypothesis, the effects of shrubs on the physical environment and individual plant growth did not increase across the established stress gradient at this site. At the community level, shrub patches increased beta diversity, and contained greater rarified richness and exotic plant cover than shrub-free patches. Shrub effects on rarified richness increased with environmental stress, but effects on exotic cover and beta diversity did not. Our study provides evidence for the community-level effects of shrubs as ecosystem engineers in this system, but shows that these effects do not necessarily become stronger in more stressful environments.

14 CFR 23.49 - Stalling period.

Code of Federal Regulations, 2010 CFR

2010-01-01

... which the airplane is controllable with— (1) For reciprocating engine-powered airplanes, the engine(s... more than 110 percent of the stalling speed; (2) For turbine engine-powered airplanes, the propulsive..., VSOand VS1at maximum weight must not exceed 61 knots for— (1) Single-engine airplanes; and (2...

Civil propulsion technology for the next twenty-five years

NASA Technical Reports Server (NTRS)

Rosen, Robert; Facey, John R.

1987-01-01

The next twenty-five years will see major advances in civil propulsion technology that will result in completely new aircraft systems for domestic, international, commuter and high-speed transports. These aircraft will include advanced aerodynamic, structural, and avionic technologies resulting in major new system capabilities and economic improvements. Propulsion technologies will include high-speed turboprops in the near term, very high bypass ratio turbofans, high efficiency small engines and advanced cycles utilizing high temperature materials for high-speed propulsion. Key fundamental enabling technologies include increased temperature capability and advanced design methods. Increased temperature capability will be based on improved composite materials such as metal matrix, intermetallics, ceramics, and carbon/carbon as well as advanced heat transfer techniques. Advanced design methods will make use of advances in internal computational fluid mechanics, reacting flow computation, computational structural mechanics and computational chemistry. The combination of advanced enabling technologies, new propulsion concepts and advanced control approaches will provide major improvements in civil aircraft.

Assessment of n-pentanol/Calophyllum inophyllum/diesel blends on the performance, emission, and combustion characteristics of a constant-speed variable compression ratio direct injection diesel engine.

PubMed

Ramakrishnan, Purnachandran; Kasimani, Ramesh; Peer, Mohamed Shameer; Rajamohan, Sakthivel

2018-05-01

Alcohol is used as an additive for a long time with the petroleum-based fuels. In this study, the higher alcohol, n-pentanol, was used as an additive to Calophyllum inophyllum (CI) biodiesel/diesel blends at 10, 15, and 20% by volume. In all blends, the ratio of CI was maintained at 20% by volume. The engine characteristics of the pentanol fuel blends were compared with the diesel and CI20 (Calophyllum inophyllum 20% and diesel 80%) biodiesel blend. The nitrogen oxide (NO) emission of the pentanol fuel blends showed an increased value than CI20 and neat diesel fuel. The carbon dioxide (CO 2 ) also increased with increase in pentanol addition with the fuel blends than CI20 fuel blend and diesel. The carbon monoxide (CO) and hydrocarbon (HC) emissions were decreased with increase in pentanol proportion in the blend than the CI20 fuel and diesel. The smoke emission was reduced and the combustion characteristics of the engine were also improved by using pentanol blended fuels. From this investigation, it is suggested that 20% pentanol addition with the biodiesel/diesel fuel is suitable for improved performance and combustion characteristics of a diesel engine without any engine modifications, whereas CO 2 and NO emissions increased with addition of pentanol due to effective combustion.

Engine Icing Modeling and Simulation (Part 2): Performance Simulation of Engine Rollback Phenomena

NASA Technical Reports Server (NTRS)

May, Ryan D.; Guo, Ten-Huei; Veres, Joseph P.; Jorgenson, Philip C. E.

2011-01-01

Ice buildup in the compressor section of a commercial aircraft gas turbine engine can cause a number of engine failures. One of these failure modes is known as engine rollback: an uncommanded decrease in thrust accompanied by a decrease in fan speed and an increase in turbine temperature. This paper describes the development of a model which simulates the system level impact of engine icing using the Commercial Modular Aero-Propulsion System Simulation 40k (C-MAPSS40k). When an ice blockage is added to C-MAPSS40k, the control system responds in a manner similar to that of an actual engine, and, in cases with severe blockage, an engine rollback is observed. Using this capability to simulate engine rollback, a proof-of-concept detection scheme is developed and tested using only typical engine sensors. This paper concludes that the engine control system s limit protection is the proximate cause of iced engine rollback and that the controller can detect the buildup of ice particles in the compressor section. This work serves as a feasibility study for continued research into the detection and mitigation of engine rollback using the propulsion control system.

Quiet engine program flight engine design study

NASA Technical Reports Server (NTRS)

Klapproth, J. F.; Neitzel, R. E.; Seeley, C. T.

1974-01-01

The results are presented of a preliminary flight engine design study based on the Quiet Engine Program high-bypass, low-noise turbofan engines. Engine configurations, weight, noise characteristics, and performance over a range of flight conditions typical of a subsonic transport aircraft were considered. High and low tip speed engines in various acoustically treated nacelle configurations were included.

The effect of abrading and cutting instruments on machinability of dental ceramics.

PubMed

Sakoda, Satoshi; Nakao, Noriko; Watanabe, Ikuya

2018-03-16

The aim was to investigate the effect of machining instruments on machinability of dental ceramics. Four dental ceramics, including two zirconia ceramics were machined by three types (SiC, diamond vitrified, and diamond sintered) of wheels with a hand-piece engine and two types (diamond and carbide) of burs with a high-speed air turbine. The machining conditions used were abrading speeds of 10,000 and 15,000 r.p.m. with abrading force of 100 gf for the hand-piece engine, and a pressure of 200 kPa and a cutting force of 80 gf for the air-turbine hand-piece. The machinability efficiency was evaluated by volume losses after machining the ceramics. A high-abrading speed had high-abrading efficiency (high-volume loss) compared to low-abrading speed in all abrading instruments used. The diamond vitrified wheels demonstrated higher volume loss for two zirconia ceramics than those of SiC and diamond sintered wheels. When the high-speed air-turbine instruments were used, the diamond points showed higher volume losses compared to the carbide burs for one ceramic and two zirconia ceramics with high-mechanical properties. The results of this study indicated that the machinability of dental ceramics depends on the mechanical and physical properties of dental ceramics and machining instruments. The abrading wheels show autogenous action of abrasive grains, in which ground abrasive grains drop out from the binder during abrasion, then the binder follow to wear out, subsequently new abrasive grains come out onto the instrument surface (autogenous action) and increase the grinding amount (volume loss) of grinding materials.

40 CFR 87.1 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF AIR... turboprop engines. Class TF means all turbofan or turbojet aircraft engines or aircraft engines designed for... turbine engines employed for propulsion of aircraft designed to operate at supersonic flight speeds...

NREL: News - Prototype Low-Emissions Natural Gas Engine Saves Fuel

Science.gov Websites

/heavy_vehicle/natgas_pub.html#engine for a copy of the full NREL report, "Development of a Throttleless engines. In testing, the prototype engine operated over the full speed and load range, delivering 250

Performance of a High-Speed Compression-Ignition Engine Using Multiple Orifice Fuel Injection Nozzles

NASA Technical Reports Server (NTRS)

Spanogle, J A; Foster, H H

1930-01-01

This report presents test results obtained at the Langley Memorial Aeronautical Laboratory of the National Advisory Committee for Aeronautics during an investigation to determine the relative performance of a single-cylinder, high-speed, compression-ignition engine when using fuel injection valve nozzles with different numbers, sizes, and directions of round orifices. A spring-loaded, automatic injection valve was used, centrally located at the top of a vertical disk-type combustion chamber formed between horizontally opposed inlet and exhaust valves of a 5 inch by 7 inch engine.

Preliminary Results of Altitude-Wind-Tunnel Investigation of X24C-4B Turbojet Engine. IV - Performance of Modified Compressor. Part 4; Performance of Modified Compressor

NASA Technical Reports Server (NTRS)

Thorman, H. Carl; Dupree, David T.

1947-01-01

The performance of the 11-stage axial-flow compressor, modified to improve the compressor-outlet velocity, in a revised X24C-4B turbojet engine is presented and compared with the performance of the compressor in the original engine. Performance data were obtained from an investigation of the revised engine in the MACA Cleveland altitude wind tunnel. Compressor performance data were obtained for engine operation with four exhaust nozzles of different outlet area at simulated altitudes from 15,OOO to 45,000 feet, simulated flight Mach numbers from 0.24 to 1.07, and engine speeds from 4000 to 12,500 rpm. The data cover a range of corrected engine speeds from 4100 to 13,500 rpm, which correspond to compressor Mach numbers from 0.30 to 1.00.

An investigation of crankshaft oscillations for cylinder health diagnostics

NASA Astrophysics Data System (ADS)

Geveci, Mert; Osburn, Andrew W.; Franchek, Matthew A.

2005-09-01

The vibrational characteristics of an internal combustion engine crankshaft are investigated from a cylinder health diagnostics point of view. Experimental results from a six-cylinder industrial diesel engine are presented to demonstrate the effects of cylinder imbalance on the individual harmonic components of the engine speed signal. A crank-angle domain numerical model of the crankshaft dynamics for a six-cylinder industrial diesel engine is also adopted to establish the effects of continuous low-power production in individual cylinders of a multi-cylinder engine. Outline of a diagnostics algorithm that makes use of the properties of crankshaft vibration behaviour is provided. In particular, crank-angle domain notch filters are employed to extact the harmonic components of engine speed. The outlined method can be implemented for individual cylinder health diagnostics across a family of multi-cylinder engines and can be formulated to handle changes in crankshaft characteristics due to replacement of mechanical components and/or wear.

46 CFR 184.620 - Propulsion engine control systems.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 7 2014-10-01 2014-10-01 false Propulsion engine control systems. 184.620 Section 184... Communications Systems § 184.620 Propulsion engine control systems. (a) A vessel must have two independent means of controlling each propulsion engine. Control must be provided for the engine speed, direction of...

46 CFR 184.620 - Propulsion engine control systems.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 7 2013-10-01 2013-10-01 false Propulsion engine control systems. 184.620 Section 184... Communications Systems § 184.620 Propulsion engine control systems. (a) A vessel must have two independent means of controlling each propulsion engine. Control must be provided for the engine speed, direction of...

46 CFR 184.620 - Propulsion engine control systems.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 7 2011-10-01 2011-10-01 false Propulsion engine control systems. 184.620 Section 184... Communications Systems § 184.620 Propulsion engine control systems. (a) A vessel must have two independent means of controlling each propulsion engine. Control must be provided for the engine speed, direction of...