Computational Investigation of Effects of Side-Injection Geometry on Thrust-Vectoring Performance in a Fuel-Injected Dual Throat Nozzle

Abstract

Dual-throat Nozzle (DTN) is known as one of the most effective approaches of fluidic thrust-vectoring. It is gradually flourishing into a promising technology to implement supersonic and hypersonic thrust-vector control in aircrafts. The main objective of the present study is numerical investigation of the effects of secondary injection geometry on the performance of a fuel-injected planar dual throat thrust-vectoring nozzle. The main contributions of the study is to consider slot and circular geometries as injector cross-sections for injecting four different fuels; moreover, the impact of center-to-center distance of injection holes for circular injector is examined. Three-dimensional compressible reacting simulations have been conducted in order to resolve the flowfield in a dual throat nozzle with pressure ratio of 4.0. Favre-averaged momentum, energy and species equations are solved along with the standard k − ε model for the turbulence closure, and the eddy dissipation model (EDM) for the combustion modelling. Second-order upwind numerical scheme is employed to discretize and solve governing equations. Different assessment parameters such as discharge coefficient, thrust ratio, thrust-vector angle and thrust-vectoring efficiency are invoked to analyze the nozzle performance. Computationally predicted data are agreed well with experimental measurements of previous studies. Results reveal that a maximum vector angle of 17.1 degrees is achieved via slot injection of methane fuel at a secondary injection rate equal to 9% of primary flow rate. Slot injection is performing better in terms of discharge coefficient, thrust-vector angle and thrust-vectoring efficiency, whereas circular injection provides higher thrust ratio. At 2% secondary injection for methane fuel, vector angle and vectoring efficiency obtained by slot injector is 8% and 34% higher than the circular injector, respectively. Findings suggest that light fuels offer higher thrust ratio, vector angle and vectoring efficiency, while heavy fuels have better discharge coefficient. Increasing center-to-center distance of injector holes improves thrust ratio, while having a negative effect on discharge coefficient, vector angle and vectoring efficiency. A comparison between fuel injectant of current study and inert injectant in the previous studies indicates that fuel reaction could exhibit substantial positive effects on vectoring performance. Secondary-to-primary momentum flux ratio is found to play a crucial role in nozzle performance.

Aircraft Thrust Vector Control Using Variable Vanes; Numerical Simulation and Optimization

“…It is obvious that by increasing the number of neurons and the number of hidden layers, the model becomes more accurate; however, this improvement is stopped, and an opposite pattern is observed when overfitting occurs. Therefore, the selected model is (32,64,128,256,128,64,32). After selecting the number of hidden layers, the impact of different activation functions for the output layer is investigated in Table 4.…”

“…Salimi. et al [32] focused on the numerical investigation of the impact of secondary injection geometry on the performance of a fuel-injected planar dual throat thrust-vectoring nozzle.…”