Numerical Investigation of Geometrical Influence On Isolator Performance

The three dimensional Reynolds Averaged Navier Stokes (RANS) Computational Fluid Dynamics analysis has been employed to study the influence of geometrical shape transition on performance of scramjet isolators. The pre-combustion shock train also called pseudo shock which appears in the subsonic combustion mode in dual mode scramjet isolator is analyzed in shape transitioned isolators. A square isolator and a shape transitioned square to circular isolator configurations having same length and cross sectional areas were considered. The simulations were carried on isolator geometries for inlet conditions of Mach 2 and unit Reynolds number of 12.4x106/m. The pressure rise due to heat addition in combustion chamber is modeled with back pressure 3.8 times higher than the inlet static pressure. The Numerical results match with the experimental data obtained from literature and with the waltrup and Billig correlation. The length of pseudo shock is compared in these isolators and it is found that it is shorter for square to circular configuration.