Shock Reduction Through Opposite jets: Atmospheric Entry Vehicles

Abstract

The effect of opposing jets on atmospheric reentry vehicles is studied using computational fluid dynamics. Reentry is a strenuous task, especially in the case of manned entries. High drags, excessive g loads, and extreme aero-heating are experienced by the Atmospheric Reentry Vehicles. Initially, the reentry vehicles were designed for ballistic entries, but due to the high g loads experienced by the astronauts, the reentry vehicles were then designed to have lifting capabilities. This study aims to explore maximum drag and temperature reduction using opposite jets. Four nozzle configurations were studied on the Orion reentry capsule no-jet, single-nozzle-jet, multiple-nozzle jets located at the vehicle’s periphery, and adjacent jets to the stagnation point of the vehicle. The results indicate that a single nozzle and multiple nozzles adjacent to the stagnation point are effective drag and heat reduction agents. The cases were studied for variable pressure ratios from 0.8 up to 2.2. A single nozzle at 0.8 pressure ratio reduces the drag up to 40%; at higher pressure ratios it can reach up to 65%. In the case of multiple nozzles adjacent to the stagnation point at a pressure ratio of 0.8, there is a 60% drag reduction and at higher pressure ratios this value can reach up to 85%. At the same time, periphery jets, on the other hand, are good deceleration agents due to the thrust force generated by the opposing jets. For the cases, where the thrust coefficient value is less than 0.1, the aerodynamic forces are dominated and from 0.1 to 1 there is an influence of both aerodynamic and thrust forces. The variation of jet performance with an angle of attack was also studied. The effect of the angle of attack is more adverse on single-nozzle jets than on multiple-nozzle jets. The former can conserve their performance even at extreme angles of attack.