Variable-cycle engines for supersonic cruising aircraft

Willis, E. A.; Welliver, A. D.

doi:10.2514/6.1976-759

Cited by 11 publications

(5 citation statements)

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“…11 The most attractive variable cycle engine solution for fighter aircraft is variable geometry turbine technology. 12,13 In 1950, NASA and others had already researched variable geometry turbine technology. 14,15 Later, RR Company also further verified that changing the stator blade installation Angle could control turbine flow and achieve the purpose of variable circulation.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on the aerodynamic performance of variable geometry low-pressure turbine adjustable guide vanes

Yao

Xiang

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part A:

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An annular cascade testing rig of a variable-geometry low-pressure turbine with a large expansion angle was designed and built, combining a five-hole probe, a surface static pressure test system, and a PIV(Particle Image Velocimetry) measurement system. The effects of exit Mach numbers (0.2, 0.3, 0.4), turning angles (−1.5°, 0°, 3°), and adjustable device diameters (30 mm, 40 mm) on turbine cascade aerodynamic performance were experimentally investigated. Numerical simulations were also carried out to gain more insight into the flow fundamentals. Results show that the endwall clearance and the adjustable device significantly influence the flow field, with leakage flows before, after, and around the disc. The leakage vortex and passage vortex formation resulted in two high-loss regions in the shroud and hub endwall regions. The aerodynamic loss structures at the exit section were similar at different Mach numbers and varied considerably at different turning angles. Besides, a larger area of the adjustable device (d = 40 mm) was found to reduce the leakage loss caused by upper and lower clearance leakage flows and inhibit the development of secondary flows, resulting in a more straightforward secondary flow structure and a smaller influence range. Quantitatively, the adjustable device with a diameter of 40 mm could decrease the average total pressure loss coefficients by 11.5%, 16.6%, and 6.3% at three turning angles (−1.5°, 0°, 3°), respectively, compare to the adjustable device with a diameter of 30 mm.

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Section: Introductionmentioning

confidence: 99%

Experimental study on the aerodynamic performance of variable geometry low-pressure turbine adjustable guide vanes

Yao

Xiang

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part A:

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“…One way to greatly increase effectiveness is to improve engine performance, which lowers fuel consumption and decreases the aircraft weight for a given mission. To help make the engines more efficient across many flight conditions, researchers previously developed and evaluated variable cycle engines (VCEs) to help tailor performance across the flight envelope [5,6,7,8,9].…”

Section: Introductionmentioning

confidence: 99%

Multipoint Variable Cycle Engine Design Using Gradient-Based Optimization

Jasa

Gray

Seidel

et al. 2019

AIAA Scitech 2019 Forum

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Supersonic aircraft are challenging to optimally design due to the widely varying constraints and flight conditions they experience. Additionally, a large number of disciplinary subsystems must be considered due to highly complex design requirements. One subsystem that has a major effect on overall performance is the engine. In this work, we construct a supersonic mixed-flow variable cycle engine and perform multipoint gradient-based optimization using this model. We see that the operational variables allow the optimizer to tailor performance at each individual flight condition, leading to better overall performance. To simulate airframe integration constraints, we run successive optimizations with increasingly restrictive inlet areas and see decreases in engine performance. This work is part of a larger effort to incorporate engine design into aero-thermal-mission optimization of a supersonic aircraft.

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“…They concluded that variable geometry turbine showed improved off-design performance. However, the numerical research of Bringhenti [5] showed that the VGT improved turbine performances at the cost of reducing the surge margin of compressor component.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Unsteady Aerodynamic Excitation on Rotor Blade of Variable Geometry Turbine

Liu

Qiao

Duan

2019

International Journal of Rotating Machinery

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To investigate the aerodynamic excitations in variable geometry turbines, the full three-dimensional viscous unsteady numerical simulations were performed by solving N-S equations based on SAS SST method. The aerodynamic excitations at varied expansion ratios with six different vane stagger angles that cause the unsteady pressure fluctuation on the rotor blade surface are phenomenologically identified and quantitatively analyzed. The blade pressure fluctuation levels for turbines with different vane stagger angles in the time and frequency domain are analyzed. As the results suggest, the blade excitation mechanisms are directly dependent on the operating conditions of the stage in terms of vane exit Mach numbers for all test cases. At subsonic vane exit Mach numbers the blade pressure fluctuations are simply related to the potential filed and wake propagation; at transonic conditions, the vane trailing edge shock causes additional disturbance and is the dominating excitation source on the rotor blade, and the pressure fluctuation level is three times of the subsonic conditions. The pressure fluctuation energy at subsonic condition concentrates on the first vane passing period; pressure fluctuation energy at higher harmonics is more prominent at transonic conditions. The variation of the aerodynamic excitations on the rotor blade at different vane stagger angles is caused by the varied expansion with stator and rotor passage. The aerodynamic excitation behaviors on the rotor blade surface for the VGT are significantly different at varied vane stagger angle. Spanwise variation of the pressure fluctuation patterns on is also observed, and the mechanism of the excitations at different spans is not uniform.

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Variable-cycle engines for supersonic cruising aircraft

Cited by 11 publications

References 0 publications

Experimental study on the aerodynamic performance of variable geometry low-pressure turbine adjustable guide vanes

Experimental study on the aerodynamic performance of variable geometry low-pressure turbine adjustable guide vanes

Multipoint Variable Cycle Engine Design Using Gradient-Based Optimization

Investigation of Unsteady Aerodynamic Excitation on Rotor Blade of Variable Geometry Turbine

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