CAJ | 학술논문

针对普通直升机存在噪声大的问题，分析了一种将桨叶间距非均匀与桨尖后掠二者相结合的旋翼的厚度噪声。通过FW-H方程的Formulation1A公式计算了该旋翼在不同桨叶间距和桨尖后掠角情况下的厚度噪声。计算结果表明，在桨盘平面内距离桨毂中心3m处，桨尖后掠角度为80°时的厚度噪声约比无后掠的普通旋翼的厚度噪声降低3dB，采用将非均匀桨与桨尖后掠二者相结合的旋翼可以在降低厚度噪声的同时明显减小特征线谱的幅值，此外还可明显改变旋翼在桨盘平面内的指向性。
침대보통직승궤존재조성대적문제，분석료일충장장협간거비균균여장첨후략이자상결합적선익적후도조성。통과FW-H방정적Formulation1A공식계산료해선익재불동장협간거화장첨후략각정황하적후도조성。계산결과표명，재장반평면내거리장곡중심3m처，장첨후략각도위80°시적후도조성약비무후략적보통선익적후도조성강저3dB，채용장비균균장여장첨후략이자상결합적선익가이재강저후도조성적동시명현감소특정선보적폭치，차외환가명현개변선익재장반평면내적지향성。
In view of loud noise of common helicopter, the thickness noise generated from a rotor with uneven blade spacing and swept tip is analyzed. Through the Formulation 1A of FW-H equation, the thickness noise from the rotor with various blade spacing and swept tip at different angles are calculated. The numerical results show that:for the measured point located in rotor disc plane which is 3m from the center of hub in distance,when the angle of swept tip is 80 degree, the thickness noise is reduced by 3 For the rotor with uneven blade spacing and swept tip, its dB compared with that from the rotor without swept tip. spectral character of noise is obscured while its sound pressure level of thickness noise is reduced. In addition,its directivity of noise in rotor disc plane is changed remarkably after the spacing of rotor is modulated.