Numerical study on dimension reduction of variable cycle compression system based on turbulent jet theory
The mode selection valve is an important component to change thermodynamic cycle parameters in the mode transition process of the variable cycle compression system.In the performance analysis of the com-pression system,the balance between high computational efficiency and computational accuracy is an important part of the researchers'attention.In this paper,a reduced-dimensional numerical method based on turbulent jet theory is established and applied to the numerical simulation of variable cycle compression system.The calcula-tion results are compared with the sudden expansion reduced-dimensional numerical method and the full three-dimensional mode selection valve numerical method.The results show that:the reduced-dimensional numerical method based on the turbulent jet theory can predict the pressure loss of the valve more accurately.Compared with the sudden expansion reduced-dimensional numerical method,the average error decreases from 19.41%to 5.60%.At the small opening,the reduced-dimensional numerical method based on the turbulent jet theory can more accurately obtain the total pressure ratio and the bypass ratio of the front fan during the mode transition pro-cess.The prediction error of the total pressure ratio decreases from 1.07%to 0.15%,and the prediction error of the bypass ratio decreases from 32.38%to 3.50%.At the large opening,the accuracy of the new reduced-dimen-sional numerical method is equivalent to the sudden expansion reduced-dimensional numerical method.By corre-lating the upstream and downstream aerodynamic parameters of the mode selection valve in the bypass,a relative-ly accurate downstream velocity distribution of the mode selection valve is obtained,so the new method based on the turbulent jet theory can be used for the numerical simulation of the variable cycle compression system.
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