Experimental Study of Combined Cycle Engine Combustor in Scramjet-Mode

A rocket based combined cycle engine was tested in scramjet-mode. The combustor model had two rockets in the combustor section. These rockets were used not only for thrust production unit, but also for fuel supply unit. The test facility consisted of an air supply section, a combustor section, a straight duct section, and a divergent duct section. Total pressure of the supplied air was 1 MPa, and the total temperature of the air was 2400 K. In the tests, in order examine the effect of the length of the straight duct section, four kinds of length of straight duct were connected downstream to the rockets. Two combustion patterns were observed for different lengths of straight duct. Pitot pressure and gas sampling were measured on the exit plane of the combustor model. Better combustion conditions were attained in the case of a longer duct. Nomenclature A = cross section Fc = impulse function of combustion gas L = length of straight duct section (including the straight part of combustor downstream of rocket) Pw = wall pressure Pwi = wall pressure at the entrance of the combustor W = width of the straight duct section x = distance from the position of the rocket nozzle exit along the airflow direction y = vertical distance from the bottom z = transverse distance from sidewall surface (rocket side) (O/F)r = mass flow ratio of oxygen to fuel in the rocket φ = equivalence ratio to airflow ηc = combustion efficiency