Interaction of external flow with linear cluster plug nozzle jet
Plug nozzle flow in the presence of external flow is experimentally investigated at free-stream Mach numbers of 0.0, 0.7, 0.9, 1.1, and 1.5. The internal nozzle is operated in overexpanded and underexpanded regimes for these external flow Mach numbers. For the subsonic external flow, slight changes in the plug jet flow are observed as compared to the no-external-flow case. The supersonic external flow introduces substantial changes to plug flow jet structure as well as the wave interactions within it, as compared to the no-external-flow case. For the overexpanded internal nozzle operation, the oblique shock waves are asymmetric within the plug core jet. For underexpanded internal nozzle operation, an oblique shock formation is noticed on the plug surface which induces flow separation downstream. The RMS of the pressure fluctuations indicates a distinct peak corresponding to the foot of the overexpansion shock on the plug surface. These peaks are observed at consistent pressure ratios for all the external flow conditions considered. Regarding the cluster plug nozzle flow field, three-dimensional flow features are noticed because of the intermodule interactions. For both the overexpanded and underexpanded internal jet conditions, the interactions between the modules are predominantly compression waves in the spanwise direction. The RMS of the pressure fluctuations measured along the intermodule centreline suggests that the spanwise wave interactions have considerable influence on the flow unsteadiness.
KeywordsJet flow Altitude adaptive nozzle Cluster plug nozzle Overexpansion Underexpansion
The authors wish to thank National Aerospace Laboratories (NAL), India, for funding this study as an in-house project. The technical support of A. Narayanswamy and V. Biju of the base flow facility during the test campaigns is gratefully acknowledged. Funding was provided by Council of Scientific and Industrial Research.
- 1.Griffith, A.A.: Jet propulsion nozzle for use at supersonic jet velocities. Patent Number 2,683,962, Rolls-Royce Limited, 20 July 1954Google Scholar
- 2.Berrier, B.L.: Effect of plug and shroud geometry variables on plug nozzle performance at transonic speeds. NASA TN D-5098 (1969)Google Scholar
- 3.Onofri, M.: Plug Nozzles: Summary of flow features and engine performance. 40th AIAA Aerospace Sciences Meeting & Exhibit, AIAA Paper 2002-0584, Jan 14–17 (2002). https://doi.org/10.2514/6.2002-584
- 5.Tsutsumi, S., Yamaguchi, K., Teramoto, S., Nagashima, T.: Clustering effects on performance and heating of a linear aerospike nozzle. 45th AIAA Aerospace Sciences Meeting and Exhibit, AIAA Paper 2007-122 (2007). https://doi.org/10.2514/6.2007-122
- 6.Tomita, T., Takahashi, M., Onodera, T., Tamura, H.: A simple performance prediction model of clustered linear aerospike nozzles. 37th Joint Propulsion Conference and Exhibit, AIAA Paper 2001-3560 (2001). https://doi.org/10.2514/6.2001-3560
- 7.Besnard, E., Garvey, J.: Aerospike engines for nanosat and small launch vehicles (NLV/SLV). Space 2004 Conference and Exhibit, AIAA Paper 2004-6005 (2004). https://doi.org/10.2514/6.2004-6005
- 10.Reijasse, P., Corbel, B.: Basic experiments on non-adaptation phenomena in aerospike nozzles. 15th Applied Aerodynamics Conference, AIAA Paper 1997-2303 (1997). https://doi.org/10.2514/6.1997-2303
- 11.Bannink, W.J., Houtman, E.M., Schoones, M.M.J.: On the interaction between a linear plug nozzle exhaust flow and supersonic external flow. In: Harris, R.A. (ed.) Proceedings of the 3rd European Symposium on Aerothermodynamics for space vehicles, ESA SP vol. 426. European Space Agency (ESA) (1999)Google Scholar
- 12.Vuillamy, D., Duthoit, V., Berry, W.: European investigation of clustered plug nozzles. 35th Joint Propulsion Conference and Exhibit, AIAA Paper 1999-2350 (1999). https://doi.org/10.2514/6.1999-2350
- 13.Hagemann, G., Immich, H., Dumnov, G.: Critical assessment of the linear plug nozzle concept. 37th Joint Propulsion Conference and Exhibit, AIAA Paper 2001-3683 (2001). https://doi.org/10.2514/6.2001-3683