Abstract:

The High Flow Dual Variable Cycle Engine （HFDVCE） achieves high performance by the aerodynamic and thermodynamic schemes such as synchronous combination of high flow rate， high throttle ratio， bypass ratio， and boost ratio regulation in the full speed range， as well as high turbine front temperature， meeting the requirements of low-speed economy and high-speed high thrust. Compared to conventional engines， HFDVCE has more prominent aerodynamic stability issues within the full range and mode switching. This article conducts research on the aerodynamic stability of HFDVCE， and proposes an HFDVCE model with instability simulation to address the lack of overall instability simulation and parameter mismatch between sub-models under multiple operating conditions. Firstly， a high-precision nonlinear model of the engine was established based on the component method to obtain the aerodynamic parameters of compression components. Then， a dynamic modeling method for aerodynamic instability of compression components was proposed. By introducing a torque term to characterize the influence of rotational speed on the characteristics of the instability model， an instability model with two types of unstable conditions， stall and surge， was established to avoid the assumption of constant rotational speed and solve the problem of coefficient mismatch between multiple instability sub-models. Furthermore， the coupling relationship between the instability model of compression components and the nonlinear model of the engine was clarified. The impact of aerodynamic instability of the compression system on the overall performance of the engine was characterized by the instability coefficient， and an HFDVCE model with instability simulation was established to achieve dynamic simulation of overall instability. Finally， simulation experiments were conducted on four typical instability modes of HFDVCE， verifying the effectiveness of the model and providing a simulation platform for active stability control design.

Key words: component level model, compressor instability dynamics, high flow dual variable cycle engine, stall and surge, instability simulation