Mathematical Model Design and Validation of Mode Selection Valves for Variable Cycle Compression Systems

The present one-dimensional model shows inadequate accuracy in predicting mode selection valve performance when operating with small openings, necessitating modifications. This study based on two-dimensional wall jet theory through experiments and numerical simulations methods, reveals the similarity distribution of downstream total pressure and the streamwise total pressure decay characteristics of mode selection valve. A mathematical model suitable for small opening conditions was developed and integrated with the sudden expansion model for large opening conditions to create a new hybrid model. Verification shows that under three typical throat Mach numbers, the prediction error of the total pressure recovery coefficient for the entire operating range is less than 2.5%, demonstrating its effectiveness as a simplified mathematical model for predicting mode selection valve performance.