振动壁面上的高超音速三维流动转捩的模式研究

Predicting laminar-turbulent transition in hypersonic boundary layers plays a key role in the design of future space vehicles operating at sustained hypersonic speeds. So far, there are few published investigations into the wall-oscillation effect upon three-dimensional boundary-layer transition, which could become more difficult in hypersonic flow regime due to the existence of oscillating shock waves. In fact, without consideration of such effect, it cannot be predicted by the present numerical methods that the large transitional flow region occurring on the leeward side of space vehicles in flight tests. Therefore, based on the linear/nonlinear stability theories, in combination with modern CFD methods, this work is firstly to develop numerical methods of high fidelity, in order to resolve the mean hypersonic flow-field of three-dimensional boundary layers with wall/shock oscillation. Then, stability analysis is to be carried out to understand the instability/transition mechanism in such flows. Consequently, a new transition/turbulence model will be proposed and validated in this study that takes into account the rational effects of wall/shock oscillation in hypersonic flows, which could be used for the design of space vehicles.

准确预测由层流向湍流的转捩过程是高超声速飞行器设计的重点和难点之一。对于实际飞行中机体振动及其导致的激波振荡影响转捩过程的问题，国内尚无相关技术积累，国外也未见任何研究发表。而现有的未考虑该影响的转捩预测模型无法模拟飞行试验中飞行器背风面出现大范围流动转捩的现象。因此，本课题拟根据线性/非线性流动稳定性理论，结合现代计算流体力学技术，首先发展高精度的数值方法，获得存在壁面振动和激波振荡的高超音速三维边界层流场；进而揭示流动失稳机理，归纳出壁面振动和激波振荡对流动转捩的影响规律；在此基础上，建立相应的适用于大规模并行计算的湍流/转捩模式，为实际高超音速飞行器的设计和改进提供理论依据和技术支持。

层流向湍流的转捩预测是高超声速飞行器设计的关键问题。对于实际飞行中机体振动及其导致的激波振荡影响转捩过程的问题，国内尚无相关技术积累，国外也未见任何研究发表。本项目首次系统性地研究了振动壁面对转捩的影响机理，并在此基础上建立了壁面振动条件下高超声速三维边界层流动的湍流/转捩模式。该模式成功应用于我国高超声速飞行器真实外形转捩预测的整机计算，服务于全机的气动外形设计，并经过多发飞行试验验证，而国外目前尚无全机转捩预测报道。