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 (∆%T,jet = +22.6% and ∆%Isp,Tjet = +2.9% at cµ = 0.168) and nitrogen gaseous flows (∆%T,jet = +36.1% and ∆%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.
Thrust augmentation of micro-resistojets by steady micro-jet blowing into planar micro-nozzle
Fontanarosa D.;De Giorgi M. G.;Ficarella A.
2021-01-01
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 (∆%T,jet = +22.6% and ∆%Isp,Tjet = +2.9% at cµ = 0.168) and nitrogen gaseous flows (∆%T,jet = +36.1% and ∆%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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
