Abstract
The efficiency of tabs of two geometries in promoting the mixing of a Mach 2 elliptic jet has been studied. Limiting tab of triangular and circular geometry (crosswire) of 5 % blockage placed along major and minor axis at the nozzle exit, are tested for nozzle pressure ratio from 4 to 8, in steps of one. Both tabs are efficient mixing promoters, at all the tested NPRs, when placed along the minor axis. But along major axis the crosswire retards the mixing, at all the NPRs. The triangular tab along the major axis is also found to retard the mixing at NPRs 4 and 5, but for nozzle pressure ratios above 5 it causes mixing enhancement even when placed along the major axis. The triangular tab is found to be a better mixing promoter than the crosswire. The maximum core length reduction of 88 % is caused by triangular tab along the minor axis is at NPR4. The corresponding core length reduction for the crosswire is only 72 %. Shadowgraph pictures of controlled jets show that both tabs weaken the waves in jet core. The geometry and orientation of the tab and the expansion level influence the mixing caused by the tab.
References
1. Ahuja KK, Brown WH. “Shear flow control by mechanical tabs,” AIAA Paper 89–0994, 1989.10.2514/6.1989-994Search in Google Scholar
2. Bohl D, Foss JF. “Enhancement of passive mixing tabs by the addition of secondary tabs,” AIAA Paper 96–054, 1996.10.2514/6.1996-545Search in Google Scholar
3. Zaman KB, Reeder MF, Samimy M. Control of an axisymmetric jet using vortex generators. Phys Fluids 1994;6:778–93.10.1063/1.868316Search in Google Scholar
4. Takama Y, Suzuki K, Rathakrishnan E. Visualization and size measurement of vortex shed by flat and arc plates in an uniform flow. Int Rev Aerosp Eng Eng Feb. 2008;1:55–60.Search in Google Scholar
5. Thanigaiarasu S, Jayapraksh S, Elangovan S, Rathakrishnan E. Influence of tab geometry and its orientation on underexpanded sonic jets. Inst Mech Eng (U K), Part G, J Aerosp Eng 2008;222:331–9.10.1243/09544100JAERO299Search in Google Scholar
6. Bradbury LJ, Khadem AH. The distortion of a jet by tabs. J Fluid Mech 1975;70:801–13.10.1017/S0022112075002352Search in Google Scholar
7. Wishart DP, Krothapalli A, Mungal MG. Supersonic jet control disturbances inside the nozzle. AIAA J 1993;31:1340–1.10.2514/3.11773Search in Google Scholar
8. Zaman KB. “Streamwise Vorticity Generation and Mixing Enhancement in Free Jets byb Delta-Tabs”, AIAA Paper 93–3253, 1993.10.2514/6.1993-3253Search in Google Scholar
9. Reeder MF, Samimy M. The evolution of a jet with vortex- generating tabs: real-time visualisation and quantative measurements. J Fluid Mech 1996;311:72–118.10.1017/S0022112096002510Search in Google Scholar
10. Gretta WJ, Smith CR. The flow structure and statistics of a passive mixing tab. J Fluids Eng 1993;115:255–63.10.1115/1.2910133Search in Google Scholar
11. Bradbury LJ, Khadem AH. The distortion of a jet by tabs. Jof Fluid Mech Aug. 1975;70:801–13.10.1017/S0022112075002352Search in Google Scholar
12. Krothapalli A, Wishart DP. Supersonic jet control via point disturbances inside the nozzle. AIAA J 1993;31:1340–134.10.2514/3.11773Search in Google Scholar
13. Singh NK, Rathakrishnan E. Sonic jet control with tabs. Int J Turbo Jet Eng 2002;19:107–18.10.1515/TJJ.2002.19.1-2.107Search in Google Scholar
14. Zaman KB, Reeder MF, Samimy M. Effect of tab geometry on the flow and noise field of an axisymmetric jet. AIAA J 1993;31(4):609–619.10.2514/3.11594Search in Google Scholar
15. Rathakrishnan E. Experimental studies on the limiting tab. AIAA J 2009;47:2475–85.10.2514/1.43790Search in Google Scholar
16. Lovaraju P, Paparao KP, Rathakrishnan E. “Shifted cross wire for Supersonic Jet Control,” AIAA Paper 2004–4080, 2004.Search in Google Scholar
17. Kaushik M, Takur PS, Rathakrishnan E. Studies on the effect of notches on circular sonic jet mixing. J Propul Power Jan-Feb. 2006;22:219–27.10.2514/1.8424Search in Google Scholar
18. Clement S, Rathakrishnan E. Characteristics of sonic jet with tabs. Shock Waves 2006;15:219–27.10.1007/s00193-006-0017-2Search in Google Scholar
19. Lovaraju P, Rathakrishnan E. Subsonic and transonic jet control with crosswire. AIAA Journal 2006;44:2700–5.10.2514/1.17637Search in Google Scholar
20. Lovaraju P, Clement S, Rathakrishnan E. Effect of crosswire and tabs on sonic jet structure. Shock Waves 2007;17:71–83.10.1007/s00193-007-0092-zSearch in Google Scholar
21. Lovaraju P, Rathakrishnan E. Shifted crosswire for jet flow control. Int Rev Aerosp Eng Feb. 2008;1:61–8.Search in Google Scholar
22. Thanigaiarasu S, Elangovan S, Rathakrishnan E. Effect of arc-tabs on the mixing characteristics of subsonic and sonic jets. Int Rev Aerosp Eng Feb. 2008;1:69–76.Search in Google Scholar
23. Thanigaiarasu S, Jayaprakash S, Elangovan S, Rathakrishnan E. Influence of tab geometry and its orientation on underexpanded sonic jets. J Aerosp Eng 2008;222:331–9.Search in Google Scholar
24. Aravindh Kumar SM, Rathakrishnan E. Characteristics of controlled Mach 2 elliptic jet. J Propul Power January–February 2016;32:121–33, DOI: 10.2514/1.B35877.Search in Google Scholar
25. Rathakrishnan E. Gas dynamics, 5nd ed. Delhi, India: PHI Learning Pvt. Ltd, 2014.Search in Google Scholar
26. Aravindh Kumar SM, Rathakrishnan E. Characteristics of controlled Mach 2 elliptic jet. Jl Propul Power 2015, DOI: 10.2514/1.B35877.Search in Google Scholar
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