Thrust Augmentation of Micro-Resistojets by Steady Micro-Jet Blowing into Planar Micro-Nozzle

Abstract

The present work investigates the impact of steady micro-jet blowing on the performance of a planar micro-nozzle designed for both liquid micro-thrusters and nitrogen cold-gas micro-resistojets. Two micro-injectors have been placed into the divergent region along the sidewalls, injecting a secondary flow of propellant perpendicularly to the wall where they have been located. The micro-jet actuator configuration is characterized by the dimensionless momentum coefficient cμ. The best performance improvement is retrieved at the maximum cμ for both water vapor (Δ%T,jet = +22.6% and Δ%Isp,Tjet = +2.9% at cμ = 0.168) and nitrogen gaseous flows (Δ%T,jet = +36.1% and Δ%Isp,Tjet = +9.1% at cμ = 0.297). The fields of the Mach number and the Schlieren computations, in combination with the streamline visualization, reveal the formation of two vortical structures in the proximity of secondary jets, which energize the core flow and enhance the expansion process downstream secondary jets. The compressible momentum thickness along the width-wise direction θxy in presence of secondary injection reduces as a function of cμ. In particular, it becomes smaller than the one computed for the baseline configuration at cμ > 0.1, decreasing up to about and -57% for the water vapor flow at cμ = 0.168, and -64% for the nitrogen gaseous flow at cμ = 0.297.

Bulletin of the Polish Academy of Sciences: Technical Sciences

“…[2]. In the case of active controls, the researchers utilized a high-speed nozzle with an expanded duct and microjet controller; a small hole is drilled in the base region to control the flow, which was proven to be an efficient approach for the supersonic flow problem [3,4].…”

“…The study demonstrated that base pressure was controlled effectively through the employment of micro jets. Khan and Rathakrishnan [3] conducted experiments to modify base pressure. M = 1.87, 2.2, and 2.58, and NPR = 3, 5, 7, 9, and 11, were utilized as control parameters.…”

“…2a. The exit diameter of the nozzle may be maintained constant while fabricating a C-D nozzle, as the base pressure findings for nozzles with an exit diameter are available in the literature [2][3][4][5]. The isentropic relations were used to compute the throat diameter [13].…”