Uncertainty Analysis of Supersonic Biplane's Aerodynamic Characteristics

考虑不确定性的超声速双翼气动特性分析

School of Aeronautics, Northwestern Polytechnical University, Xi'an 710072, China

Received: 18 September 2018

Abstract

Utilizing the interference of shock and expansion waves, supersonic biplane can reduce the wave drag remarkably. However, the supersonic biplane is only designed at special conditions, so that it has poor performance at off-design conditions. To analyze supersonic biplane's aerodynamic characteristics at off-design conditions, the non-instructive probabilistic collocation method has been employed to achieve uncertainty quantification. Besides, Sobol global sensitivity is adopted to accurately evaluate the influence of the input uncertainty parameters. The uncertainty parameters are Mach number and the angle of attack which both satisfy special normal distributions. Aerodynamic coefficients and pressure distribution from the biplane's surface as well as flow filed are studied. The results of uncertainty quantification show that the main reason for aerodynamic characteristics fluctuations is the pressure pulsation from the maximum thickness of the lower airfoil's upper surface. The results of global sensitivity show that Mach number is the most important factor for the variation of aerodynamic performance.

摘要

超声速双翼是一种利用激波和膨胀波相互干涉以消除激波阻力的构型。然而，双翼属于单一工作状态设计，为了衡量双翼在设计点附近的稳健性，采用非嵌入式概率配置点不确定性分析方法及Sobol全局灵敏度分析方法，研究双翼在典型工况条件下不确定性扰动对气动特性波动的影响情况。分析了在马赫数和迎角满足特定正态分布的随机扰动下，双翼表面、全流场压强的分布和气动力系数。不确定性分析结果表明，下单翼翼型最大厚度区域的压力脉动是造成气动特性波动的主要原因。灵敏度分析结果表明，马赫数是对双翼气动性能影响最大的因素。