【作者】 陈晨；

【导师】 林麒；

【作者基本信息】 厦门大学 ， 飞行器设计， 2020， 硕士

【摘要】 桨尖涡是直升机噪声的主要来源之一,为了降低直升机噪声,本文提出采用主动控制和被动控制的方法来抑制桨尖涡发展的方案。主动控制的方法是在桨尖设置等离子体合成射流激励器,利用垂直于桨尖端面的射流干扰桨尖涡的形成过程来抑制桨尖涡的发展。被动控制的方法是将桨尖设计成类羽状的仿生桨尖,利用新型桨尖与来流的作用抑制桨尖涡的形成过程。首先,通过数值模拟,比较了合成射流的参数对抑制桨尖涡的影响。通过比较发现,在相同的射流速度下,增大射流直径有利于抑制桨尖涡。随后,研究了来流Ma数对四孔射流抑制桨尖涡的影响,结果表明,在来流Ma=0.3-0.7的范围内,4孔射流模型都能有效抑制桨翼桨尖涡的发展。同时对于射流抑制桨尖涡的机理进行了分析探讨,表明合成射流对桨尖涡形成具有干扰作用,一方面降低了桨尖端面速度,从而降低桨尖端面涡量值来抑制桨尖后缘处桨尖涡的强度;另一方面射流通过抑制桨尖端面和上方漩涡的形成与发展来抑制桨尖后缘处桨尖涡的形成和发展。其次,利用仿生学原理设计了一种新型的类羽状桨尖。数值模拟结果表明,仿生类羽状桨尖后缘的桨尖涡中心涡量值以及涡核强度明显弱于正常桨叶。通过改变新型类羽状桨尖的结构参数,对桨尖涡的抑制效果不同。9mm四波峰羽状结构的新型桨尖能使桨尖涡中心涡量值以及涡核旋转角速度降低一半左右。在来流Ma=0.3-0.7的范围内,新型类羽状结构的桨尖均能不同程度地抑制桨尖涡。然后结合主/被动两种控制方法,将合成射流布置在类羽状桨尖处,选择合理的射流位置,可获得更加明显的抑制桨尖涡的效果。最后,进行了风洞试验对计算仿真结果进行验证,验证合成射流以及4波峰羽状结构桨尖模型对桨尖涡的抑制效果。试验结果证明,射流以及根据仿生学思想设计的新型类羽状桨尖在低速情况下能有效抑制旋翼的桨尖涡发展。本文的研究结果将为等离子体合成射流以及仿生学思想应用于抑制桨尖涡,降低桨涡干扰造成的直升机噪声的工程应用提供具有实际意义的指导。更多还原

【Abstract】 Tip vortex is one of the main sources of helicopter noise.We propose active and passive control methods to suppress the development of tip vortex.The active method is to set up plasma synthetic jet actuator at the tip of the propeller,and use the jet to destroy the stable structure inside the tip vortex to accelerate the self dissipation of the tip vortex.The passive method is to design a featherlike bionic tip,which can delay the formation of tip vortex by using the action of new tip and air.Firstly,the influence of the parameters of the synthetic jet hole on the suppression of the tip vortex is compared by numerical simulation.It can be seen that the arrangement of 4 jet holes with diameter of 2mm at an interval of 15mm near the leading edge of the blade is the best way to restrain the tip vortex.We study the influence of the inflow Mach number on the suppression of the tip vortex by it.The results show that the four hole jet model can still effectively suppress the development of the tip vortex.At the same time,the mechanism of the jet restraining the tip vortex is analyzed.The jet can effectively reduce the speed of the surrounding area,thus reducing the central vorticity value of the tip vortex and can destroy the internal structure of the tip vortex and inhibit its formation and development.Secondly,a new feather like propeller tip is designed based on the principle of bionics.The feather like structure is arranged at the top of the propeller tip.The numerical simulation results show that the vorticity and the strength of the vortex core in the trailing edge of the bionic tip are significantly weaker than those in the normal blade.By changing the structural parameters of the new featherlike tip,the suppression effect of the tip vortex will also be affected.The 9mm four wave Pinnacle structure can reduce the central vorticity and core strength of the tip vortex by about half.By changing the Mach number,the new feather like structure can still suppress the tip vortex.The effect of combined tip on the control of tip vortex is more obvious.Finally,the wind tunnel test was carried out to verify the simulation results,and the suppression effect of synthetic jet and four wave Pinnacle structure on tip vortex was verified.The experimental results show that the jet and the new feather like structure designed according to bionics can effectively restrain the tip vortex development of rotor at low speed.The results of this paper will provide practical guidance for the application of plasma synthetic jet and Bionics in the suppression of tip vortex and the reduction of helicopter noise caused by the interference of tip vortex.更多还原