COMPUTATIONAL INVESTIGATION OF THE BYPASS DUAL THROAT FLUIDIC THRUST VECTORING NOZZLE

Abstract

The thrust vector orientation is a proven idea for improving maneuverability, control efficiency, survivability, performance, and stealth characteristic of the aircraft. The thrust vector control system is gradually being introduced into modern aircraft and missiles to enhance military capabilities. The Bypass Dual-Throat Nozzle (BDTN) control is a new fluidic thrust vectoring technique that can achieve better vectoring performance with large vector angles and low thrust loss. BDTN doesn’t involve a secondary flow injection, as a bypass passage is introduced in the upstream throat of the conventional dual throat nozzle. In the present investigation, a numerical parametric study was carried out by varying bypass angle, nozzle convergence, angle and bypass width to understand the effect of these parameters on the overall performance of BDTN. All simulations used RNG k-𝜖 turbulence model for Nozzle Pressure Ratio (NPR= 2∼10) to capture the significance of under-expanded and over-expanded jets. Results show that by increasing the bypass angle from 35° to 90°, there is a 6% decrease in vectoring angle and an 18% decrease in vectoring efficiency. There is, however, an increase of 3% in the thrust coefficient and discharge coefficient. Additionally, when the convergence angle was increased from 22° to 37°, vectoring angle, discharge coefficient, and thrust coefficient increased by 2%, 1%, and 0.26%, respectively. Increasing the convergence angle from 22° to 37° was reported to decrease vectoring efficiency by about 8%. Based on this research, it was determined that nozzle convergence angle and bypass angle do not significantly affect thrust vectoring performance, however, bypass width had a significant effect on thrust vectoring performance. After investigating the parametric performance of BDTN, an attempt has been made to integrate a bypass dual throat nozzle on an actual aircraft engine and analyze the flow characteristics and performance parameters due to this integration. Three different BDTN geometries have been investigated by steady numerical simulation to compare the thrust vectoring performance and losses for all three configurations.