scholarly journals Drag Management in High Bypass Turbofan Nozzles for Quiet Approach Applications

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
P. Shah ◽  
A. Robinson ◽  
A. Price ◽  
Z. Spakovszky
Keyword(s):  
Noise Level ◽  
Jet Noise ◽  
Swirl Flow ◽  
Test Facility ◽  
Engine Thrust ◽  
Configuration Change ◽  
Swirl Angle ◽  
Maximum Benefit ◽  
Air Brakes ◽  
Flow Drag

The feasibility of a drag management device that reduces engine thrust on approach by generating a swirling outflow from the fan (bypass) nozzle is assessed. Deployment of such “engine air-brakes” (EABs) can assist in achieving slower and/or steeper and/or aeroacoustically cleaner approach profiles. The current study extends previous work from a ram air-driven nacelle (a so-called “swirl tube”) to a “pumped” or “fan-driven” configuration and also includes an assessment of a pylon modification to assist a row of vanes in generating a swirling outflow in a more realistic engine environment. Computational fluid dynamics (CFD) simulations and aeroacoustic measurements in an anechoic nozzle test facility are performed to assess the swirl-flow-drag-noise relationship for EAB designs integrated into two NASA high-bypass ratio (HBPR), dual-stream nozzles. Aerodynamic designs have been generated at two levels of complexity: (1) a periodically spaced row of swirl vanes in the fan flowpath (the “simple” case), and (2) an asymmetric row of swirl vanes in conjunction with a deflected trailing edge pylon in a more realistic engine geometry (the “installed” case). CFD predictions and experimental measurements reveal that swirl angle, drag, and jet noise increase monotonically but approach noise simulations suggest that an optimal EAB deployment may be found by carefully trading any jet noise penalty with a trajectory or aerodynamic configuration change to reduce perceived noise on the ground. Constant speed, steep approach flyover noise predictions for a single-aisle, twin-engine tube-and-wing aircraft suggest a maximum reduction of 3 dB of peak tone-corrected perceived noise level (PNLT) and up to 1.8 dB effective perceived noise level (EPNL). Approximately 1 dB less maximum benefit on each metric is predicted for a next-generation hybrid wing/body aircraft in a similar scenario.

scholarly journals Drag Management in High Bypass Turbofan Nozzles for Quiet Approach Applications

2011 ◽  
Author(s):  
P. Shah ◽  
A. Robinson ◽  
A. Price ◽  
Z. Spakovszky
Keyword(s):  
Noise Level ◽  
Jet Noise ◽  
Swirl Flow ◽  
Test Facility ◽  
Engine Thrust ◽  
Configuration Change ◽  
Swirl Angle ◽  
Maximum Benefit ◽  
Air Brakes ◽  
Flow Drag

The feasibility of a drag management device that reduces engine thrust on approach by generating a swirling outflow from the fan (bypass) nozzle is assessed. Deployment of such “engine air-brakes” (EABs) can assist in achieving slower and/or steeper and/or aero-acoustically cleaner approach profiles. The current study extends previous work from a ram air-driven nacelle (a so-called “swirl tube”) to a “pumped” or “fan-driven” configuration, and also includes an assessment of a pylon modification to assist a row of vanes in generating a swirling outflow in a more realistic engine environment. Computational fluid dynamics (CFD) simulations and aero-acoustic measurements in an anechoic nozzle test facility are performed to assess the swirl-flow-drag-noise relationship for EAB designs integrated into two NASA high-bypass ratio (HBPR), dual-stream nozzles. Aerodynamic designs have been generated at two levels of complexity: (1) a periodically spaced row of swirl vanes in the fan flowpath (the “simple” case), and (2) an asymmetric row of swirl vanes in conjunction with a deflected trailing edge pylon in a more realistic engine geometry (the “installed” case). CFD predictions and experimental measurements reveal that swirl angle, drag, and jet noise increase monotonically, but approach noise simulations suggest that an optimal EAB deployment may be found by carefully trading any jet noise penalty with a trajectory or aerodynamic configuration change to reduce perceived noise on the ground. Constant speed, steep approach flyover noise predictions for a single-aisle, twin-engine tube-and-wing aircraft suggest a maximum reduction of 3 dB of peak tone-corrected perceived noise level (PNLT) and up to 1.8 dB effective perceived noise level (EPNL). Approximately 1 dB less maximum benefit on each metric is predicted for a next-generation hybrid wing/body aircraft in a similar scenario.

Simultaneous Noise and Performance Measurements for High-Speed Jet Noise Reduction Technologies

2009 ◽  
Author(s):  
Dean Long ◽  
Steven Martens
Keyword(s):  
Noise Reduction ◽  
High Speed ◽  
Near Field ◽  
Jet Noise ◽  
Source Distribution ◽  
Test Facility ◽  
Wave Radiation ◽  
Far Field ◽  
Shock Cell ◽  
Field Noise

Model scale tests are conducted to assess the Noise/Performance trade for high speed jet noise reduction technologies. It is demonstrated that measuring the near field acoustic signature with a microphone array can be used to assess the far field noise using a procedure known as acoustic holography. The near field noise measurement is mathematically propagated producing an estimate of the noise level at the new location. Outward propagation produces an estimate of the far field noise. Propagation toward the jet axis produces the source distribution. Tests are conducted on convergent/divergent nozzles with three different area ratios, and several different chevron geometries. Noise is characterized by two independent processes: Shock cell noise radiating in the forward quadrant is produced when the nozzle is operated at non-ideally expanded conditions. Mach wave radiation propagates into the aft quadrant when the exhaust temperature is elevated. These results show good agreement with actual far field measurements from tests in the GE Cell 41 Acoustic Test Facility. Simultaneous performance measurement shows the change in thrust coefficient for different test conditions and configurations. Chevrons attached to the nozzle exit can reduce the noise by several dB at the expense of a minimal thrust loss.

A New Test Facility for Investigating the Interaction Between Swirl Flow and Wall Cooling Films in Combustors

2009 ◽  
Author(s):  
B. Wurm ◽  
A. Schulz ◽  
H.-J. Bauer
Keyword(s):  
Gas Turbines ◽  
Static Pressure ◽  
Thermal Analyses ◽  
Thermal Studies ◽  
Swirl Flow ◽  
Operating Conditions ◽  
Test Facility ◽  
Wall Region ◽  
Test Rig ◽  
Combustor Liner

Swirl stabilization of flames is typically used in combustors of aero engines and gas turbines for power generation. In the near wall region of the combustor liner, the swirling flow interacts in a very particular way with wall cooling films. This interaction and its effect on the local wall cooling performance gave reason to design and commission a new atmospheric test rig for detailed aerodynamic and thermal studies. The new test rig includes three burners in a planar arrangement. Special emphasis was placed on the simulation of realistic operating conditions as Reynolds number and temperature ratio. The liner cooling and the formation of a starter cooling film can be independently controlled. The rectangular flow channel is equipped with large windows to allow for laser optical diagnostics like PIV and 3-component LDA. The thermal analyses are based on highly resolved temperature mappings of the cooled surface utilizing infrared thermography. First experimental results are presented in terms of static pressure distributions on the combustor liner and PIV contour plots of the swirl flow. The static pressure pattern corresponds well to the up wash and downwash regions of the swirl flow.

From Measurement Uncertainty to Measurement Communications, Credibility, and Cost Control in Propulsion Ground Test Facilities

1985 ◽  
Vol 107 (2) ◽  
pp. 165-172 ◽  
Author(s):  
R. E. Smith ◽  
S. Wehofer
Keyword(s):  
Measurement Uncertainty ◽  
Cost Control ◽  
Performance Testing ◽  
Evaluation Process ◽  
Test Facility ◽  
Engine Test ◽  
Measurement Evaluation ◽  
Engine Thrust ◽  
Improve Measurement ◽  
Ground Test

In the past several years significant advances have been made in altitude ground test facilities with respect to measurement accuracy and measurement cost control. To a large measure, the advances have been the result of the application of comprehensive measurement uncertainty evaluation programs. This paper discusses the specific measurement evaluation process used in the Engine Test Facility, Arnold Engineering Development Center. To explain this process, the reader is guided through the measurement process for engine thrust, an extremely critical parameter for propulsion performance testing. Although this paper focuses on the measurement of engine thrust, the overall objective is the general measurement evaluation process and its uses. The approach presented can be applied to any type measurement system. First, an overview of the measurement uncertainty methodology and its application in altitude engine test cells is presented. The paper concludes with a discussion of how measurement uncertainty results can be utilized to improve measurement understanding and presents the means to identify factors that must be controlled to achieve a reliable and accurate measurement assessment.

Design and Development of a Convective Air-Cooled Turbine and Test Facility

1961 ◽  
Vol 83 (1) ◽  
pp. 9-17
Author(s):  
W. F. Weatherwax
Keyword(s):  
Axial Flow ◽  
Weight Ratio ◽  
Fold Increase ◽  
Test Facility ◽  
Inlet Temperature ◽  
Air Cooling ◽  
Turbine Inlet Temperature ◽  
Jet Engine ◽  
Engine Thrust ◽  
Turbine Inlet

Demands for higher jet engine thrust-to-weight ratios to satisfy the needs for high Mach number and vertical take-off aircraft are continually increasing. Since World War II, the three-fold increase in thrust-to-weight ratio can be attributed almost entirely to the development of lightweight construction and the axial-flow compressor, and little credit can be given to the meager 200-F increase in turbine-inlet temperature. Increasing turbine-inlet temperature, beyond present-day material limits of 1600-1700 F, by convective air cooling, will increase the jet-engine thrust-to-weight ratio and will markedly improve the performance of the turboprop and bypass engines. The partial results of a program undertaken by the author’s company to develop a fully cooled, flight-type, turbine and test facility are reported. The design heat-transfer considerations are discussed, the test facility described, and performance results to date are given.

Jet noise reduction using co-axial swirl flow with curved vanes

2017 ◽  
Vol 126 ◽  
pp. 149-161 ◽  
Author(s):  
P. Balakrishnan ◽  
K. Srinivasan
Keyword(s):  
Noise Reduction ◽  
Jet Noise ◽  
Swirl Flow

Experimental Analysis on the Formation of CO-NO-HC in Swirling Flow Combustion Chamber

2015 ◽  
Vol 72 (4) ◽  
Author(s):  
Mohamad Shaiful Ashrul Ishak ◽  
Mohammad Nazri Mohd. Jaafar ◽  
Wan Zaidi Wan Omar
Keyword(s):  
Combustion Chamber ◽  
Swirling Flow ◽  
Swirl Flow ◽  
Recirculation Region ◽  
Mixing Rate ◽  
Swirl Angle ◽  
Low Emission ◽  
Air Mixing ◽  
Efficient Combustion ◽  
Hc Emissions

The main purpose of this paper is to evaluate the production of CO-NO-HC emissions while varying the swirl angle of curve vane radial swirler. Swirling flow generates central recirculation region (CRZ) which is necessary for flame stability and enhances fuel air mixing. Therefore designing an appropriate air swirler is a challenge to produce stable, efficient and low emission combustion inside burner system. Four radial curved vane swirlers with 30o, 40o, 50o and 60o vane angles corresponding to swirl numbers of 0.366, 0.630, 0.978 and 1.427 respectively were used in this experiment to measure the vane angles effect on emission production in the combustion chamber. Emission measurements were conducted at 5 axial distances from the burner throat, and at 5 locations along the radius starting the central axis at each section. It was found that at the core near the throat, CO and HC concentrations are low due to high available O2 and high fuel mixing rate producing efficient combustion. This is due to the high shear region created the high swirl flow.

A Test Rig for the Investigation of the Performance and Flow Field of Tesla Friction Turbines

2014 ◽  
Author(s):  
Constantin Schosser ◽  
Stefan Lecheler ◽  
Michael Pfitzner
Keyword(s):  
Flow Field ◽  
Mechanical Design ◽  
Performance Evaluations ◽  
Test Facility ◽  
Cfd Simulations ◽  
Tomographic Piv ◽  
Swirl Angle ◽  
Theoretical Investigations ◽  
Flow Phenomena ◽  
And Performance

The paper summarizes the development and optimization of a flexible test facility for 3D tomographic PIV/PTV measurements of the flow field in the rotor gap of a Tesla friction turbine and performance evaluations. The main aim of the experiment will be the validation of CFD simulations. Another intention is to gain a deeper understanding of the flow phenomena in the gap. The extension of existing theoretical investigations lead to an improved knowledge of dimensioning such bladeless turbines with the goal of maximum power and efficiency. The mechanical design of the rotor, based on these equations, was optimized for a minimal deformation and low mechanical stress. Modal and harmonic response analyses due to imbalance forces have been performed to ensure low vibrations during operation. The design of the feed and guide vanes have been optimized for uniformity of the flow entering the Tesla disk’s gap. The rotor outlet is optimized to achieve minimal pressure loss at the intended exit swirl angle. For the demonstration of the measurement technique preliminary tomographic PIV/PTV tests have been carried out. The measurement, safety monitoring and feedback-control software was developed for running on a National Instruments compact RIO real-time target.

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