An airfoil optimization method based on quadratic function to suppress fan shock noise

Abstract

The invention discloses a blade profile optimization method based on a quadratic function and capable of inhibiting shock wave noise of a fan. The method comprises the steps of two-dimensional blade profile optimization and three-dimensional blade profile optimization; the shape of a leading edge and the shape of a suction surface are optimized, the shock wave noise of the ultrasonic blade profile is reduced, meanwhile, the pneumatic performance is improved, and the thickness of the leading edge is considered to ensure the requirement of the structural strength; and the change rule of the action range and the amplitude of the quadratic function in the unfolding direction is reasonably set to adapt to the change of the blade profile thickness and the incoming flow condition so as to realize the smoothness and continuity of different blade height motif stages in a three-dimensional system. According to the method, a one-variable quadratic function is introduced into a shape function of a blade profile numerical expression so that the thickness distribution of the suction surface in the fitting range can be effectively changed, the total amount of the limit mach point forward expansion waves can be increased, the strength of the forward-extension shock waves can be weakened, and therefore the shock wave noise can be reduced, the shock wave noise of the ultrasonic blade profile or a cross-acoustic rotor can be effectively reduced by about 2-3dB, and the efficiency of the cross-acoustic rotor can be effectively improved by about 0.3%.

Description

technical field [0001] The invention relates to the field of aeroengine fan noise control, in particular to a quadratic function-based blade shape optimization method capable of suppressing fan shock wave noise. Background technique [0002] With the increasing awareness of environmental protection, the airworthiness standards for aircraft noise are becoming increasingly stringent, and noise indicators are getting more and more attention in the design stage of aero-engines. The United States has launched the Advanced Subsonic Aircraft Noise Reduction Program (AST) and the Quiet Aircraft Technology Research Program (QAT), the European Union has successively launched a series of engine noise reduction programs such as RESOUND, JEAN, and SILENCE; the fan is one of the core components of the turbofan engine. The proportion is increasing, especially for transacoustic fans, the shock wave noise generated is one of the main noise sources during the take-off stage of the aircraft, w...

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Problems solved by technology

[0002] With the increasing awareness of environmental protection, the airworthiness standards for aircraft noise are becoming increasingly stringent, and noise indicators are getting more and more attention in the design stage of aero-engines. The United States has launched the Advanced Subsonic Aircraft Noise Reduction Program (AST) and the Quiet Aircraft Technology Research Program (QAT), the European Union has successively launched a series of engine noise reduction programs such as RESOUND, JEAN, and SILENCE; the fan is one of the core components of the turbofan engine. The proportion is increasing, especially for transacoustic fans, the shock wave noise generated is one of the main noise sources during the take-off stage of the aircraft, which has a huge impact on the environment near the airport; the remarkable feature of the shock wave noise is its radiated sound waves The frequency characteristics and modal characteristics are extremely complex, which makes the noise reduction characteristics of the acoustic lining drop sharply. For low modes, the sound absorption is only 1-2dB, which is far from meeting the noise reduction requirements of aero-engines.

[0003] Existing studies have shown that the shape of the leading edge has a great influence on the aerodynamic performance of the airfoil, and the pressure ratio and efficiency of the fan / compressor can be greatly improved by rationally designing the shape of the leading edge and the suction surface; the method for optimizing the subsonic blade shape is relatively mature , there are already design criteria such as D factor, and for the supersonic blade shape, the more common method is to use genetic algorithm, given the objective function such as efficiency, etc., to iteratively calculate the blade shape to obtain the optimized blade shape; on the one hand, this The calculation time of the method is long. On the other hand, the leading edge of the optimized airfoil is too thin to meet the requirements of the blade strength, so it is difficult to apply in engineering; previous studies on the shape of the leading edge are all focused on its In terms of the influence of aerodynamic performance, this invention proposes a leading edge and suction surface design optimization method for the first time, which can reduce shock wave noise by changing the wave system structure while improving aerodynamic performance, and can ensure that the leading edge has sufficient thickness at the same time To meet the structural strength requirements

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