INFLUENCE OF THE INJECTOR INLET ANGLE ON THE FLOW AND SPRAY BEHAVIOUR OF SHEAR THINNING FLUIDS IN IMPINGING JET INJECTORS

摘要

A new experimental setup has been assembled to characterize the flow and breakup behaviour of gelled propellants under impinging jet conditions for different injector inlet angles. Pressure losses as well as shadowgraph images from two perpendicular directions have been recorded for that investigation. The pressure loss measurements showed that in the laminar flow regime, where generalized Reynolds numbers are lower than approximately 2300, the influence of the injector inlet angle is negligible. In the turbulent flow regime for generalized Reynolds numbers higher than approximately 2300, a distinct influence of the inlet angle is visible. Shadowgraph images delivered a complete spacial observation of the spray. The variation of the interior inlet angle of the impinging jet injector has less influence to the breakup characteristic of the investigated fluids than the correlation to the Reynolds number. For the presented experiments in the laminar flow region, where low generalized Reynolds numbers occur, a fluid sheet is formed at the impinging point, which decays into ligaments and finally into droplets. For the presented experiments in the turbulent region the ligament pattern is found for medium generalized Reynolds numbers and the fully developed spray regime with an immediate breakup into droplets occurs for high generalized Reynolds numbers.