Mixing Enhancement in Subsonic Jet Flow Using the Air-Tab Technique

摘要: M IXING enhancement in jet flow has long been the topic of extensive research due to its important applications aircraft propulsion and combustion. It also military importance when mixing is used suppress infrared red signature for fighter exhausts. Many passive or active approaches techniques enhance have developed explored, some these had reviewed summarized by Gutmark Grinstein [1]. In control strategies, tabs vortex generators particular are simple but effective control. Bradbury Khadem [2] were pioneers study effect solid on flow. They found that nozzle boundary-layer thickness, turbulence level, convergent ratio did not very strong influence development. On other hand, insert small rectangular into perimeter would induce profound effects Since then, many researchers working this technique. Notable examples include Samimy et al. [3], Reeder [4], Zaman [5], Yu Koh [6], Paoli [7] others. [8] conducted a systematic test series nozzles with various shapes orifices spreading most asymmetric jets was much different from round jet, biggest increase observed tabs. However, penalty introducing be significant. The thrust lost varies 4.1 23.7%when theflowblockage (proportional facing area tabs) increases 1.1 14.1%. Tominimize caused yet maintain effectiveness practical applications. Researchers searching new better minimum thrust. This Note presents results using socalled air-tab technique achieved injecting amount air (less than 1% volume rate primary jet) plume at choked speed certain attacking angles (45 90 deg respect direction). shows no impact thrust, it able provide significant as tab enhancement. A similar idea fuel mixing: example, experiments byMilanovic [9,10]. description experimental setup presented subsequently. will followed discussion. ends brief concluding remarks.