Numerical Study on the Unsteady Behavior of the Solid-Fuel Scramjet

The unsteady evolution of the flowfield in a solid-fuel scramjet is investigated. The researchers approximate the continuous working of the solid-fuel scramjet via stand-alone geometries. These directly correspond to the actual shapes of the combustor recorded during experimental tests of the engine. The flow is modeled using the compressible Navier-Stokes and species transport equations and the shear stress transport k-omega turbulence model. A two-dimensional axisymmetric formulation is employed. The fuel is the polymer polymethyl methacrylate. The integral parameters of the combustor are computed in the simulations using nonvarying geometries at discrete instants. These values are then compared with measurements taken at the same instant during the continuous working of the engine in experimental tests. The good agreement during the whole process demonstrates the permanent quasi-steadiness nature of the fluid flow in relation to the varying combustor shape. The discussion analyzes the evolution of critical combustor parameters, including thrust, fuel regression rate, and various efficiencies, and correlates them with the underlying flow variables. The findings provide valuable insights into the unsteady development of the flow physics within the combustor of a solid-fuel scramjet, contributing to a better understanding of this complex system.