Experimental investigation on the near flow field of dual stream nozzles

15th Asian Congress of Fluid Mechanics

物理学;力学

Sudhakar, S.^1 ; Karthikeyan, N.^1 ; Kumar, S. Ashwin^1

Experimental Aerodynamics Division, CSIR-National Aerospace Laboratories, Bangalore, India^1

关键词: Dual-stream nozzles;    Experimental investigations;    Near flow fields;    Operating condition;    Particle image velocimetries;    Shadowgraph technique;    Turbulence characteristics;    Turbulence level;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/822/1/012004/pdf
DOI  :  10.1088/1742-6596/822/1/012004

学科分类：力学，机械学

来源: IOP

【 摘 要 】

An experimental investigation was carried out to investigate the effect of beveling of primary nozzle exit in the near field of a dual stream nozzle flow. Two exit geometry configurations of primary stream nozzle viz., (a) circular (b) bevel along with one exit geometry of the secondary stream-circular, were studied. Experiments were carried out at both subsonic and supersonic primary nozzle operating conditions Mp=0.96 and 1.2. The secondary nozzle exit Mach number was maintained at 0.65 and 0.85 respectively to maintain the velocity ratio of 0.7 between the primary and secondary jet. The by-pass ratio for this investigation is maintained at 2.0. Flow visualization using retro-reflective shadowgraph technique was used for the qualitative visualization of the near flow field at the Mach number of 1.2. The mean and turbulent quantities in near flow field were obtained using particle image Velocimetry (2D-PIV). The flow visualization and PIV investigations show significant change in mean and turbulent quantities brought about in the near field due to the beveling of the primary nozzle. PIV results show increase in the potential core length and reduction in turbulence levels in the potential core by the secondary flow regardless of the jet exit geometry. A differential trend is seen in the shear layer growth and the turbulence characteristics between the shorter and longer lips sides of the beveled nozzle. In the dual stream configurations, bevel nozzle shows lower Reynolds stress values than the circular one except in the shorter lip side at the larger downstream locations.