头部外形对无人机气动/隐身性能影响

Influence of Head Shape on Aerodynamic/Stealth Performance of UAV

为研究头部形状对无人机气动/隐身性能的影响,建立了头部外形改进前后的分析模型。基于FLUENT和物理光学法,研究了不同状态下的气动/隐身性能影响,提出气动性能影响分析的相对变化率概念。结果表明,头部外形改进可明显提高无人机气动性能,迎角4°时,升力系数相对增加率、阻力系数相对减小率、升阻比相对增加率分别为0.2258%,5.505%,6.065%;头部外形改进后,机身下方具有更大面积的高压区而其头部高压区相对较小,增加了升力,减小了阻力;头部外形改进对散射曲线分布影响不大,前向角域RCS曲线向内收缩较大,隐身性能提高,头部外形改进在频率和俯仰角变化时均有隐身性能提升效果,频率增加时,前向角域降低幅值最大可达6.6370 dB,俯仰角变化时可达11.4577 dB;头部外形曲面融合技术可有效提高无人机气动/隐身性能。

In order to study the influence of head shape on aerodynamic/stealth performance of UAV(Unmanned Aerial Vehicle),analysis models with and without improvement of head shape are established.The effects of aerodynamic/stealth performance with different status are studied by FLUENT and physical optics method,and the conception of relative variation rate of aerodynamic performance influence analysis is proposed.The results show that the aerodynamic performance of UAV could be significantly improved by the improvement of head shape.When the angle of attack is 4°,the relative increase rate of lift coefficient,the relative reduction rate of drag coefficient,and the relative increase rate of lift-to-drag ratio are 0.2258%,5.505%and 6.065%respectively.There exists a larger high pressure area below the fuselage in improved model and its high pressure area in head is relatively small,which increases the lift and reduces the drag.The improvement of head shape has little effect on the distribution of scattering curve.The inward shrinkage of RCS curve in forward angle domain is large and the stealthy performance is improved.Besides,the improvement of head shape has lifting effect on stealth performance with the variation of frequency and pitch angle.The reduction amplitude of the forward angle domain can reach 6.6370 dB and 11.4577 dB when the frequency and pitch angle change.The surface fusion technology of head shape can effectively improve the aerodynamic/stealth performance of UAV.