Effects of mode transition on multi-dimensional coupling model of variable cycle engine

In order to study the coupling effect between mode select valve（MSV）and the overall engine-during mode transition，a typical dual ducts variable cycle engine（VCE）is studied.Firstly，a high-fidelity characteristic map of MSV is established by 3D numerical simulation of MSV model. Then，based on the component-based zero-dimensional engine aerodynamic performances calculation program，the multi-dimensional model is established by coupling high-fidelity characteristic map into the performances calculation program to study the coupling effects of MSV on the overall performances and components during the mode transition.The results of the multi-dimensional model and the zero-dimensional model are compared.The results show that，compared to the zero-dimensional model，the maximum thrust of the multi-dimensional model is 3.98% higher，and specific fuel consumption（sfc）is 0.79% higher. The fan pressure ratio is 9.86% higher at the maximum，and fan efficiencyin-creasing by 0.75%. The reason for this difference is that the multi-dimensional model correctly evaluates throttling loss of MSV in the nonlinear section，and that passes backward and affects the mixing total pressure loss in-front variable area bypass injector（FVABI）.Relying on participating in solving cooperation equations，pressure loss in FVABI significantly reduce the mass flow rate of fan duct. And under the constraint of the balance law of the engine，this makes bypass ratio decrease rapidly，and increase both of LPT’s pressure ratio and speed of low pressure spool，and then engine performances also change. Therefore，compared with the zero-dimensional model，the multi-dimensional model can truly reflect the influence of MSV on VCE performance and other components during the mode transition. © 2024 Journal of Propulsion Technology. All rights reserved.