Guidance and control algorithm of terminal normal shock for ramjet engine supercritical operation

Abstract

This thesis represents the scheme for guidance and control algorithm of terminal normal shock for ramjet engine supercritical operation. The ramjet engine is air-breathing engine for supersonic flight, it compress the incoming air via its own shape without extra facilities for compression. Incoming air flow goes through the thread of oblique shocks and finally decelerated to subsonic flow after a terminal normal shock. The position and its strength of the terminal normal shock are regarded as one of the most significant factors to evaluate engine’s efficiency. General operation of the engine may undergo through ambient disturbances which are from freestream and engine’s combustor. The disturbances alter the shock equilibrium, which cause the arbitrary variation of the shock location. As a result, the terminal shock may fall in an abnormal operation called buzz or unstart, as the shock are pulled out of engine’s intake exceeding the diffuser throat. In this thesis, the way to find optimal position of the shock is firstly studied for high efficient and stable operation of the engine. The scheme to determine optimal position is used as one possible methodology to design a guidance law. And then, the shock is guided to designated position and regulated at that point via shock position control algorithm. The details for guidance and control of the terminal shock to guarantee to hold the shock in a preferred region under the perturbations take our main part. Also, an approach is introduced to stabilize the shock under Mach number control of ramjet powered vehicle as addressing engine’s internal dynamics and the response characteristics of the shock.