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由于流体处于超声速和亚声速状态时,其性能有着显著的差异,这种现象同样存在于超声速边界层抽吸孔隙内。为了对超声速边界层抽吸孔隙内流场结构进行分类,主要通过数值计算的方法,对超声速边界层抽吸孔隙内流体的流动状态以及不同流动状态时抽吸孔隙内流场结构对抽吸腔反压的响应特点进行了研究,同时也对数值计算方法做了试验验证。数值计算采用基于有限体积法的二阶迎风格式来离散二维可压N-S方程,湍流模型采用标准k-ε模型,通过改变抽吸槽宽度D的方法来实现抽吸槽内流体处于不同的流动状态。根据抽吸槽内流体的流动状态的不同,将超声速边界层抽吸分为亚声速型,临界声速型和超声速型。分别对不同抽吸腔反压时三种抽吸类型流场结构变化特点以及声速流量系数Q变化特点进行了分析,发现不同抽吸类型对抽吸腔反压的响应规律存在显著差异。当δ/D>8.6时,即对于亚声速型抽吸而言,Q随δ/D减小而线性增加,且Q随p_c/p_0减小而减小。当δ/D<8.6时,即对于超声速型抽吸而言,Q随δ/D减小而迅速增加。另外,随p_c/p_0增加,Q先保持不变,当p_c/p_0增加到0.225时,Q开始减小,并且当p_c/p_0增加至0.675后,Q减小速率发生了突变。分析原因在于超声速型抽吸,抽吸腔反压向抽吸槽内的传递受到抽吸槽内分离区以及激波的阻碍,而对于亚声速型抽吸,抽吸腔反压能够直接传递至抽吸槽内,进而影响边界层抽吸。
As the fluid in the supersonic and subsonic state, its performance has a significant difference, this phenomenon also exists in the supersonic boundary layer pumping pores. In order to classify the flow field structure in the supersonic boundary layer suctioning aperture, the flow state of the fluid in the supersonic boundary layer pumping aperture and the flow field structure in the suctioning flow field at different flow states are mainly analyzed by numerical method. The response characteristics of backpressure were studied. At the same time, the numerical calculation method was tested. In the numerical calculation, the two-dimensional NS equations are discretized by the second-order upwind scheme based on the finite volume method. The standard k-ε model is adopted for the turbulence model. Different fluid flows in the suction tank are achieved by changing the width of the suction channel status. Supersonic boundary layer suction can be divided into sub-sonic, critical sonic and supersonic according to the different flow states of the fluid in the suction tank. The characteristics of three types of suction flow field changes and the characteristics of the sound velocity flow coefficient Q changes were analyzed respectively under different backpressures. It was found that the response of different suction types to the backpressure of the suction chamber was significantly different. When δ / D> 8.6, that is for subsonic pumping, Q increases linearly with decreasing δ / D, and Q decreases with decreasing p_c / p_0. When δ / D <8.6, ie for supersonic suction, Q increases rapidly with decreasing δ / D. In addition, with the increase of p_c / p_0, Q remains unchanged. When p_c / p_0 is increased to 0.225, Q starts to decrease, and when p_c / p_0 increases to 0.675, the rate of Q decrease changes. The reason for the analysis is that supersonic suction, the backpressure of the suction chamber into the suction chamber is hindered by the separation zone in the suction chamber and the shock wave, and for subsonic suction, the backpressure of the suction chamber can be directly transmitted to Suction tank, thus affecting the boundary layer suction.