Duration: 36 months
The core stages of most space launchers work from sea level to almost vacuum conditions. Thus, the engines would benefit from higher nozzle expansion ratios to maximize the ascent performance. Currently, this is limited due to the occurrence of uncontrolled flow-separation and dangerous side loads at lift-off [1-2]. The final goal of this research is to develop a technology that allows controlling the separation in the nozzle to avoid side loads. The proposed concept introduces plasma actuators to induce a perturbation that anchors the separation line in a specific position. Ideally, a sequence of circumferential plasma actuators could be introduced: during the ascent, the separation line is guided towards the exit by activating in sequence the different actuators. In this way, it is possible to increase the nozzle expansion ratio because the separation is controlled. The idea was previously investigated by the proposing group [3] in a performance study on the Ariane 5, showing about 250 kg increase in the payload. The feasibility of the concept is corroborated by previous experimental works [4-6] which demonstrated the effectiveness of plasma actuators in controlling the shock wave position in a supersonic inlet. This proposal aims at the development of a small-scale experiment to verify the effectiveness of plasma actuators in controlling the separation in an over-expanded nozzle. A 2D nozzle, fed by pressurized dry-air, will be instrumented with a 6-Degree-of-Freedom force balance [7] to measure side loads and optical access for the Background-Oriented Schlieren system to visualize the separation. The electrodes will be embedded in a ceramic matrix for high thermal, chemical and mechanical resistance, together with electric insulation and typically lower densities than metals [8]. The added value of these experimental activities is the realization of a proof-of-concept, together with incrementing the reliability of numerical simulations on scaled-up models.
