Experimental and Numerical Investigation of the Effects of Flow Area and Radial Position of Cascade Deswirl Nozzles on Flow Characteristics of Tubeless Vortex Reducers

A vortex reducer is employed to reduce the pressure drop during the radially inward air bleeding process in aero-engines. The vortex reducer with deswirl nozzles (DVR) has the advantage of structural robustness; however, its complex, non-monotonic flow rate–pressure drop characteristic limits its widespread application. In an effort to resolve this issue, the current study employs both experimental and numerical methodologies to investigate the effects of nozzle geometric parameters on the flow characteristics of the DVRs, which are currently deficient. The findings indicate that, irrespective of variations in nozzle radial position or flow area, an elevation in the design point flow rate invariably results in an augmented pressure drop, and this coupling effect cannot be circumvented by modifying the geometric parameters. When the nozzle radial position is lowered to below b1 = 130 mm or the flow area is reduced to below d2 = 1.19 mm, the flow characteristic of the DVRs becomes monotonic; nevertheless, due to the severely limited flow capacity, such a monotonic characteristic lacks practical engineering significance. Therefore, both the nozzle radial position and the flow area should be regarded as separate independent variables in optimization calculations during the design process, necessitating the development of a rapid and accurate low-dimensional model.