The oblique shock which equalizes the pressures on the sides of the jet boundary is the important component of the overexpanded jet shock-wave structure. If the flowfield upstream of the shock is known, the differential conditions of dynamic compatibility on gasodynamic discontinuities allows to define the flow parameters as well as their spatial derivatives behind the incident shock in the vicinity of the nozzle lip. So the deeper study of the shock incidence, its special cases and probable consequences becomes possible.
The overexpanded jet flowfield in the vicinity of the supersonic nozzle edge is studied analytically. Flow parameters (static and full pressures, Mach number, flow angle) as well as their differential characteristics dependent of incident shock (geometrical curvatures of the shock and the jet boundary, derivatives of shock strength, static and stagnation pressures, the entropy and Mach number in the compressed layer downstream the shock) are analyzed relating the defining parameters (flow Mach number upstream the shock, jet incalculability, gas specific heats ratio, jet flow symmetry type). In particular, we consider plane and axisymmetrical jets and the whole range of the theoretically possible jet incalculabilities. Extreme and zero values of the above-mentioned derivatives are defined by algebraic equations.
For example, it was shown that both the jet boundary and the incident shock can be of the untypical curvature direction (convex downwards to the plane or axis of symmetry at least in the vicinity of the nozzle lip). Shock strength (the relation of the static pressures downstream and upstream the shock) can diminish as the shock falls to symmetry plane or axis at the vicinity of the nozzle lip. This peculiarity occurs mainly at flow parameters when von Neumann paradox takes place. The experimental research discovered the shock-wave noise which points to flow auto-oscillations at the same region of flow parameters. It draws our attention to regular and Mach shock reflection problem at small jet flow Mach numbers.
Some analytical decisions deduced relate to the flow vorticity direction and gas entropy gradient. It can be useful for Taylor-Goertler instability analysis at the supersonic flow of the considered kind.
