Effect of cross wire tab orientation on twin jet mixing characteristics

• Published in: Experimental thermal and fluid science Vol. 99; pp. 344 - 356
• Main Authors: Khan, Aqib, Kumar, Rakesh, Verma, Shashi Bhushan, Manisankar, C.
• Format: Journal Article
• Language: English
• Published: Philadelphia Elsevier Inc 01.12.2018; Elsevier Science Ltd
• Subjects: Bifurcations; Core wire; Fluid dynamics; Horizontal orientation; Image enhancement; Jet flow; Mach number; Nozzles; Pressure; Pressure loss; Vertical orientation; Wire
• ISSN: 0894-1777; 1879-2286
• DOI: 10.1016/j.expthermflusci.2018.08.005

•The effect of orientation of the cross wires at the exit of two identical converging-diverging nozzles, placed close to each other, on the flow field of the twin jet is studied.•Experiments are carried out at different nozzle pressure ratios, corresponding to over-expanded to under-expanded flow conditions. Furthermore, the effect of nozzle spacing is also studied.•Cross wire has been shown to be successful in reducing the core length and enhancing the mixing characteristics of a supersonic twin jet.•The orientation of the cross wire is found to significantly influence the development of the jet flow field for twin jets for both the inter-nozzle spacings.•Wires, both mounted vertically, are found to be superior in enhancing the mixing characteristics and reducing the core length. The effect of the relative azimuthal orientation of the cross wires, placed at the exit of two identical converging-diverging nozzles, on the flow field of the twin jet is studied experimentally. The nozzle is designed for Mach number of 1.8, with the inter-nozzle spacing of 1.5 and 2.25 times the nozzle exit diameter. Pitot pressure surveys are conducted along the centerline and the cross-stream direction of the twin jet. Cross wire is shown to be successful in reducing the core length and enhancing the mixing characteristics at all the NPRs studied. The combinations of the horizontal and vertical orientation of the cross wire are found to significantly influence the development of the jet flow field for twin jets. Wires, both mounted vertically, are found to be superior in enhancing the mixing characteristics and reducing the core length. The shadowgraph images reveal that the wire bifurcates the jet and displaces the fluid away from the centerline. Strong shocks are formed near the cross wire, but the pressure losses and enhanced mixing of the jet fluid result in smaller supersonic core length with less number of shock-cells.