旋翼滑流对倾转旋翼机飞机模式下气动特性的影响
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摘要
建立了考虑旋翼桨叶形状、桨叶片数、桨距和转速等因素的等效桨盘模型,该模型中桨叶对气流的作用被等效为时间平均的源项添加到控制方程中,并通过两个算例验证了模型的有效性。对V-22倾转旋翼机飞机模式高速巡航状态下的全机三维流场进行了数值模拟,分析了旋翼流场特征,定量给出了滑流对气动力系数的影响量。计算结果表明:旋翼滑流明显改变了机翼表面的压力分布,使全机升力系数增大,最大升力系数增量为4.6%;0°迎角下滑流使阻力系数减小了29%,而4°迎角后,滑流使得阻力系数增大,在14°时增量达到了32%;俯仰力矩系数的变化量为4.6%。进一步研究发现,滑流对平尾下表面压力系数分布产生较大影响,而对垂尾影响则较小。
An equivalent actuator disk model was developed by taking into consideration such factors as the blade shape,the number of blade,blade pitch and rotating speed of rotor.This technique modelled the rotor implicitly through time averaged source terms in the equations and two test cases were used to validate the actuator disk model.The three-dimensional flow field around V-22 tiltrotor aircraft in high-speed airplane mode was simulated.The characteristics of the rotor flow field were analysed and the increments of aerodynamic coefficients caused by slipstream were also presented.The results showed that the rotor slipstream altered the pressure distributions on wing surface evidently,which increased the lift coefficients up to 4.6%.Slipstream decreased the drag coefficients about 29%at 0°angle of attack.However,after 4°angle of attack,slipstream increased the drag coefficients and the maximum increment was up to 32%.The variation of the pitching moment coefficient was also 4.6%.Further studies show that rotor slipstream has greater effect on the lower surface of the horizontal tail,while making a small impact on the vertical tail.
An equivalent actuator disk model was developed by taking into consideration such factors as the blade shape,the number of blade,blade pitch and rotating speed of rotor.This technique modelled the rotor implicitly through time averaged source terms in the equations and two test cases were used to validate the actuator disk model.The three-dimensional flow field around V-22 tiltrotor aircraft in high-speed airplane mode was simulated.The characteristics of the rotor flow field were analysed and the increments of aerodynamic coefficients caused by slipstream were also presented.The results showed that the rotor slipstream altered the pressure distributions on wing surface evidently,which increased the lift coefficients up to 4.6%.Slipstream decreased the drag coefficients about 29%at 0°angle of attack.However,after 4°angle of attack,slipstream increased the drag coefficients and the maximum increment was up to 32%.The variation of the pitching moment coefficient was also 4.6%.Further studies show that rotor slipstream has greater effect on the lower surface of the horizontal tail,while making a small impact on the vertical tail.
引文
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[19] TAI T C.Simulation and analysis of V-22tiltrotor aircraft forward-flight flowfield[J].Journal of Aircraft,1996,33(2):369-376.
[2]吴希明,仲唯贵,陈平剑.倾转旋翼机气动设计技术[J].航空科学技术,2012(4):17-24.WU Ximing,ZHONG Weigui,CHEN Pingjian.Aerodynamic design technology for tilt rotor aircraft[J].Aeronautical Science and Technology,2012(4):17-24.(in Chinese)
[3] POTSDAM M A,STRAWN R C.CFD simulations of tiltrotor configurations in hover[J].Journal of the American Helicopter Society,2005,50(1):82-94.
[4]许和勇,叶正寅,史爱明.基于非结构嵌套网格的旋翼-机身干扰流场数值模拟[J].西北工业大学学报,2010,24(6):814-817.XU Heyong,YE Zhengyin,SHI Aiming.An effective method for numerically simulating helicopter rotor-fuselage aerodynamic interference using unstructured overset grids[J].Journal of Northwestern Polytechnical University,2010,24(6):814-817.(in Chinese)
[5] RUFFIN S M,O'BRIEN D,SMITH M J,et al.Comparison of rotor-airframe interaction utilizing overset and unstructured grid techniques[R].AIAA-2004-0046,2004.
[6] LE CHUITON F.Actuator disc modelling for helicopter rotors[J].Aerospace Science and Technology,2004,8(4):285-297.
[7] SCHWEIKHARD R.Actuator disk for helicopter rotors in an unstructured flow solver[J].Journal of the American Helicopter Society,2007,52(1):58-68.
[8] RAJAGOPALAN R G.A procedure for rotor performance,flowfield and interference:aperspective[R].AIAA-2000-0116,2000.
[9]李鹏,招启军.悬停状态倾转旋翼/机翼干扰流场及气动力的CFD计算[J].航空学报,2014,35(2):361-371.LI Peng,ZHAO Qijun.CFD calculations on the interaction flowfield and aerodynamic force of tiltrotor/wing in hover[J].Acta Aeronautica et Astronautica Sinica,2014,35(2):361-371.(in Chinese)
[10] POLAK D R,REHM W,GEORGE A R.Effects of an image plane on the tiltrotor fountain flow[J].Journal of the American Helicopter Society,2000,45(2):90-96.
[11] FEJTEK I G.Navier-Stokes flowfields computation of wing/rotor interaction for a tilt rotor aircraft in hover[R].NASA TM 02-185011,1993.
[12] ABRAS J,NARDUCCI R.Analysis of CFD modeling techniques over the MV-22tiltrotor[C]∥Proceedings of the66th Annual Forum of the American Helicopter Society.Phoenix,US:American Helicopter Society,2010:11-13.
[13] KIM C,CHUNG J.Aerodynamic analysis of tilt-rotor unmanned aerial vehicle with computational fluid dynamics[J].Journal of Mechanical Science and Technology,2006,20(4):561-568.
[14] TAI T C.Effect of midwing vortex generators on V-22aircraft forward-flight aerodynamics[J].Journal of Aircraft,2003,40(4):623-630.
[15]韩志熔,陆志良,郭同庆,等.一种三维结构网格并行算法[J].航空计算技术,2010,40(6):58-61.HAN Zhirong,LU Zhiliang,GUO Tongqing,et al.A parallel algorithm for three-dimensional structured grid[J].Aeronautical Computing Technique,2010,40(6):58-61.(in Chinese)
[16] MCKEE J W,NAESETH R L.Experimental investigation of the drag of flat plates and cylinders in the slipstream of a hovering rotor[R].NACA TN-4239,1958.
[17] KOMERATH N M,MAVRIS D M,LIOU S G.Prediction of unsteady pressure and velocity over a rotorcraft in forward flight[J].Journal of Aircraft,1991,28(8):509-516.
[18] JOHNSON W.Calculation of tilt rotor aeroacoustic model(TRAM DNW)performance,airloads,and structural loads[C]∥Proceedings of the American Helicopter Society Aeromechanics Specialists'Meeting.Atlanta,US:American Helicopter Society,2000:13-15.
[19] TAI T C.Simulation and analysis of V-22tiltrotor aircraft forward-flight flowfield[J].Journal of Aircraft,1996,33(2):369-376.