摘要
基于非定常面元/时间步进全展自由尾迹建立了旋翼/机身非定常气动干扰分析方法。方法中耦合了非定常面元法和时间步进自由尾迹,以准确模拟旋翼非定常气动力、旋翼尾迹及桨叶对机身的非定常干扰效应。为模拟前飞状态下具有升力的机身,将机身离散为汇/偶极子面元,并采用涡线镜像法模拟旋翼尾迹靠近机身表面产生的加速效应。通过计算前飞状态的Maryland、ROBIN(Rotor Body INteraction)旋翼/机身干扰下的非定常压力分布,并与可得到的实验值、CFD计算结果对比,验证方法的准确性。随后分析前飞速度、旋翼与机身距离对旋翼/机身非定气动干扰的影响。计算结果表明机身头部和中部非定常压力主要受桨叶的通过性影响,而机身尾梁主要受尾迹/机身干扰影响,机身非定常气动力频率为桨叶片数的倍频。随前飞速度的增加,机身非定常压力幅值增加,尾梁压力幅值先增加后减小;增加旋翼与机身距离将减小机身和尾梁非定常压力幅值。
Unsteady aerodynamic load on helicopter fuselage is mainly due to aerodynamic interaction of rotor and fuselage.An unsteady panel/time-step full-span free-wake method is established to accurately pre-dict the rotor/fuselage unsteady aerodynamic interaction for the vibration load analysis of whole vehicle.The unsteady panel method is used to consider unsteady aerodynamics of rotors and fuselage,and the free-wake method is applied to accurately simulate dynamics of rotor wake.Helicopter fuselage is discretizated into source/doublet panels to simulate its lift in forward flight,and vortex line mirror method is adapted to ac-count acceleration phenomenon resulted from rotor wake close to fuselage surface.To validate the accuracy of this approach,unsteady rotor/fuselage aerodynamic interaction of Maryland and ROBIN modes are simu-lated in forward flight,and compared with measured data and CFD results.Finally,the influences of ad-vanced ratio,rotor-fuselage distance on unsteady aerodynamic interaction are analyzed.It is shown that the unsteady pressure of fuselage is mainly affected by rotor blade pass effect,while that of tail boom is mainly due to the interaction of rotor wake and fuselage,and the frequency of unsteady pressure is times of blades number.Amplitude of unsteady pressure on fuselage will increase as advance ratio increases,that of tail boom,however,will increase and then decrease.Increasing rotor-fuselage distance will decrease amplitude of unsteady pressure on fuselage and tail boom.
出处
《空气动力学学报》
CSCD
北大核心
2014年第3期320-327,共8页
Acta Aerodynamica Sinica
关键词
旋翼机身干扰
非定常面元法
自由尾迹
非定常气动力
直升机
rotor/fuselage interaction
unsteady panel method
free-wake
unsteady aerodynamics
heli-copter
