Numerical Investigation on a New Concept of Shock Vector Control Nozzle

Abstract

Shock vector control (SVC) based on transverse jet injection is one of the fluidic thrust vectoring (FTV) technologies, and is considered as a promising candidate for the future exhaust system working at high nozzle pressure ratio (NPR). However, the low vector efficiency (η) of the SVC nozzle remains an important problem. In the paper, a new method, named as the improved SVC, was proposed to improve the vector efficiency (η) of a SVC nozzle, which enhances the vector control of primary supersonic flow by adopting a bypass injection. It needs less secondary flow from high pressure component of an aero-engine and has smaller influence on the working character of an aero-engine. The flow mechanism of the improved SVC nozzle was investigated by solving three-dimensional Reynolds-averaged Navier--Stokes with shear stress transport (SST) κ–ω turbulence model. The shock waves, jets-primary flow interactions, flow separation, and vector performance were analyzed. The influences of aerodynamic and geometric parameters, namely, NPR, secondary pressure ratio (SPR), and bypass injection position (Xj.ad.) on flow characteristics and vector performance were investigated. Based on the design of experiment (DOE), the response surface methodology (RSM) and the simulation model of an aero-engine, a method to estimate the coupling performance of the improved SVC nozzle and an aero-engine was studied, and a new balance relationship between the improved SVC nozzle and an aero-engine was established. Results shows that (1) with the assistance of bypass injection, the jet penetration and the capability of vector control are largely improved, resulting in a vector efficiency (η) of 1.98 deg/%-ω at the designed NPRD = 13.88; (2) in a wide range of operating conditions, larger vector angle (δp), higher thrust coefficient (Cfg), and higher vector efficiency (η) of the improved SVC nozzle were obtained, (3) in the coupling process of the improved SVC nozzle and an aero-engine, a δp of 18.1 deg was achieved at corrected secondary flow ratio of 10% and corrected bypass ratio of 6.98%, and the change of the thrust and the specific fuel consumption (SFC) were within 12%, which is better than the coupling performance of a SVC nozzle and an aero-engine.