Experimental investigation of start/unstart process during hypersonic intake at Mach 6 and its control
| Autor: | R. Saravanan, R. Kalimuthu, S. L. N. Desikan, K.J. Francise |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Flow visualization
0209 industrial biotechnology Hypersonic speed Materials science Bubble Flow (psychology) Aerospace Engineering 02 engineering and technology Unstart Mechanics 01 natural sciences 010305 fluids & plasmas law.invention symbols.namesake 020901 industrial engineering & automation Pressure measurement Mach number law Schlieren 0103 physical sciences symbols |
| Zdroj: | Aerospace Science and Technology. 113:106688 |
| ISSN: | 1270-9638 |
| DOI: | 10.1016/j.ast.2021.106688 |
| Popis: | Hypersonic intake with 20 and 30% blockage struts is experimentally investigated in Mach 6 flow. Initially the experiments are conducted with full opening of the cowl at fixed condition. The results show that the intake is started for 20% blockage struts while it is unstarted for 30% blockage struts. The unstart process for 30% blockage struts is due to large separation bubble in the engine flow path which is corroborated through steady pressure measurements, time average schlieren images, and oil flow visualization. To understand the separation bubble behaviour associated with start as well as unstart cases, a cowl opening mechanism is indigenously designed, and the experiments are performed using different cowl opening times from closed to fully opened condition. To quantify the separation bubble behaviour, unsteady pressure measurements, time-resolved schlieren images, and spectral analyses are done. For 20% blockage struts, irrespective of cowl opening time, the separation bubble size remains unaltered. In this case, increasing cowl opening time (110, 185, 350, and 700 ms) delays the separation bubble movement, and a maximum delay in the separation bubble movement is noted for 350 ms cowl opening time. It can be concluded that there exists an optimum cowl opening time at which the separation bubble movement can be restricted. Conversely, un-start process is noted for 30% blockage struts regardless of the cowl opening time where the pressure rise because of the separation bubble is found to be twice that of the 20% blockage struts, indicating a substantial increase in the separation bubble size. To alleviate the un-start process, experiments are further carried out using partial cowl opening with fixed as well as dynamic conditions. The results reveal that the un-start process is eased by opening the cowl below 90% of its full opening. |
| Databáze: | OpenAIRE |
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