NUMERICAL-ANALYSIS OF HYPERSONIC LOW-DENSITY SCRAMJET INLET FLOW

Hypersonic low-density flow around a two-dimensional scramjet inlet model has been analyzed using the direct simulation Monte Carlo (DSMC) method. The predominant features of hypersonic flows, such as a thick viscous layer due to the low-density fluid together with shock-boundary-layer interaction and shock impingement as well as shock-induced separation, are encountered in this type of flowfield. Three hypersonic flowfields with different degrees of rarefaction are investigated. The freestream Knudsen numbers of the flowfields based on the height of the duct passage are in the range of 0.02-0.12, Conventional continuum gasdynamics based on the concept of a local equilibrium may not be adequate to describe this type of flowfield accurately. The pressures obtained by the DSMC simulation are compared with available experimental data. Good agreement is obtained with previous experimental data and with theoretical solutions for similar wedge flow cases near the leading edge of the ramp centerbody. Good agreement is observed with the experimental data of Minucci and Nagamatsu except for some discrepancies, especially in the lower-density cases, which may be partially attributed to three-dimensional effects and/or to experimental uncertainty.