细长杆用于超音速飞行器降噪的数值分析

在超音速飞机头部加装合理设计的细长杆可有效降低飞行噪音.基于Fluent准三维数值模拟手段对多组细长杆设计方案进行模拟分析,对比其对远场压力的影响,以比较各类细长杆的降噪效果,根据气动理论对数值结果作出解释,揭示细长杆的降噪效果与其外形的内在联系;从远场压力最大值、远场压力曲线形状等不同方面分析细长杆对音爆的影响.结果表明:6 m长的12.5°半锥角单级锥形细长杆有明显的降噪效果;合理设计的多级细长杆可明显降低初始过压值,并能延迟远场压力达到最大值的时间;凹凹面、凹锥面、凸凹面和凸锥面的细长杆能够降低远场压力峰值,改善压力曲线的形状,具有较好的降噪作用;细长杆产生的强膨胀波能在激波传播过程中大幅削弱机头激波,从而削弱音爆水平.

Numerical analysis of slender-rod used for reduction supersonic aircraft noise

The installation of an appropriate slender-rod on the nose of supersonic aircraft is able to reduce flight noise level. Based on Fluent quasi three-dimensional numerical simulation method in this paper, 24 groups of slender-rod models are simulated and analyzed and compared in influence on the far-field pressure, to compare noise reduction effect of various slender-rod and summarize effective noise reduction model. Furthermore, from the theory of aerodynamics ,this paper explains the solution of numerical simulation ,and revealing inner relation between the slender-rod noise reduction effect and slender-rod shape. Besides, this paper analyze the influence of slender-rod to the sonic boom from the aspects of the far-field pressure maximum and curve shape etc. The results show that single-stage conical slender-rod with 6 meters length and 12.5 degrees half- cone angle has obvious effect in noise reduction; reasonable multistage conical slender-rod significantly reduces the initial overpressure value, and delay the far-field pressure peak ;concave-concave type, concave-cone type, convex-concave type and convex-cone type slender-rods greatly reduce the far-field pressure peak value and improve the shape of pressure curve and have More significant noise reduction effect ; strong expansion wave produced by slender-rod can significantly weaken the nose shock wave in the process of shock wave propagation, thereby weakening the sonic boom.