圆形截面超声速流道三维消波过程中的压力传播与几何变形

Pressure Transmission and Geometric Deformation forSupersonic Circle Section Flow in Process ofThree-Dimensional Wave Cancelling

关键词:  压力反问题  双特征线方法  局部压力扰动  几何变形  超声速流动  消波

Key words:  Pressure inverse problem  Bicharacteristics method  Local pressure disturbance  Geometric deformation  Supersonic flow  Wave cancelling

摘要:

为了研究圆截面超声速流道因局部变形而导致的消波不完全问题，该问题涉及到马赫波的三维相交、反射、聚焦及耗散作用，采用所提出的特征线消波技术，设计了壁面存在局部高/低压区的圆截面超声速消波流道；以此来探索压力波在超声速圆管中的聚焦和三维传播、消波过程中圆截面流道的变形特性、压力波与壁面变形的耦合作用、以及多扰动源产生压力波的相交过程。通过分析消波流道的流场结构，可以发现:在局部高压区下游，出现压缩波与膨胀波的马赫锥相互嵌套的三维传播形式；圆弧壁面对压力波有聚焦作用。根据消波过程中壁面的变形可以发现:壁面变形主要沿扰动源下游发展，波形沿流向不断增大而不能回归原型，即呈现发散趋势，展现了流动的非线性。采用压力的均方差对流场的均匀性进行评估，发现:弱压力扰动的流场可进行线性叠加；沿着流向扰动范围扩大，峰值减小，避免汇聚成强扰动。

Abstract:

A study of wave incomplete propagation caused by local deformation of supersonic circle section flow was discussed. The study involved three-dimensional intersection， reflection， focusing and dissipation of Mach wave. Applying a proposed wave cancelling technology， the geometrical parameters of boundary were therefore designed for supersonic circle section flow in the presence of a local high/low pressure disturbance. In the process of wave cancelling， the three-dimensional propagation，intersection，focusing and dissipation of pressure wave were explored. The geometrical deformation characteristics of wall were discussed. The coupling effect of pressure wave and wall deformation was studied. And intersecting processes of the pressure waves generated by the multi-disturbance sources were studied. By analyzing the wave cancelling flow field structure， it would be found that there was a three-dimensional propagation form in which the compressed and expanded waves were nested downstream the higher-pressure region. And the arc wall has a focusing effect on the pressure wave. According to the geometric deformation in the process of wave cancelling， it would be found that the development of boundary deformation mainly occurs along the downstream of disturbance source， playing a ripple， enlarged the ripple rather than back to prototype. It might mean that the existence of disturbances in the boundary lead to a divergent trend of physical boundary， showing the nonlinear trait of flow. Adopting the Standard Deviation of pressure to evaluate the uniformity of supersonic flow， it would be found that the flow combination of weak disturbance might be a linear process. And along the stream， rang of disturbance was enlarged， the peak of disturbance was reduced， the convergence of disturbance was avoided.