To study the duct curvature effects on a shock train in rectangular hypersonic inlet/isolator models, four curved isolators are designed and tested at a freestream Mach number of 4.92. Strong interactions between the shock train and background waves are encountered. In small curvature isolators, the shock train intersects with the left-running or right-running shock stably, with the massive separation situated near the top or bottom wall, respectively; whereas the large separation always locates near the bottom wall in large curvature isolators. When the shock train switches from intersecting with one background shock to another, rapid forward movement occurs in large curvature isolators; whereas violent flow oscillations may appear in small curvature isolators. The radial pressure gradient direction in the shock train region alternatively changes from being centripetal to being centrifugal in small curvature isolators, whereas the direction remains centripetal in large curvature isolators due to the enhanced left-running expansion waves and right-running compression waves. In addition, the amplitude of the radial pressure gradient increases with the duct curvature, which induces significant secondary flow and accumulates a large amount of low-energy fluid near the bottom surface. On the other hand, the streamwise adverse pressure gradient in the shock train decreases with the duct curvature, resulting in a longer and weaker shock train, and the maximum sustainable backpressure ratio decreases with a percentage as high as 17% of that of straight isolator. Besides, the root-mean-square values of static pressure on the exit plane can be reduced to some extent by increasing the duct curvature. In general, large duct curvature has detrimental effects on the shock train characteristics, but adequate duct curvature can help to avoid violent flow oscillation and decrease pressure fluctuating level.
Behavior of Shock Train in Curved Isolators with Complex Background Waves
AIAA Journal ; 56 , 1 ; 329-341
2018-01-01
Article (Journal)
Electronic Resource
English
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