Effect of model dimensions on the thrust characteristics of ramjet engines in tests in a short-duration facility

The effect of the absolute dimensions of ramjet models on the gas- and thermodynamics of the heat input and the overall thrust characteristics of an internal channel is investigated at Mach number $\mathrm{M}=5$ in a short-duration high-enthalpy test stand with a double prechamber. Data obtained from models with airstream intake diameters of $73.5$ and $23$ mm are compared. Increasing the linear dimensions by roughly a factor of three has no effect on the gas- and thermodynamic behavior: the main features of system operation and the thrust-economy characteristics are the same for these models. Increasing the absolute size of the step from $2.5$ to $10$ mm aids in preventing disruption of the air intake into the model because of the stabilizing effect of the step.