Design and Computational Study of TBCC Variable Nozzle with Central Body.

In order to operate efficiently in various operating conditions, a turbine-based combined cycle engine (TBCC) variable nozzle is proposed to adjust the area of the nozzle throat and the exit simultaneously. The performances of the nozzle at static condition and at different freestream Mach numbers are analyzed. Results show that the design has a preferable static performance and the thrust ratios are 0. 90, 0. 97 and 0. 98 in typical states. After the introduction of the external flow, the freestream can suppress the overexpansion of the exhaust flow effectively at the low Mach number condition (Ma = 0. 8), so the thrust coefficient is enhanced by 6.7%. In the high Mach number conditions (Ma = 2. 8,4. 0), though the flow pattern of the nozzle downstream is apparently affected by the external flow, the pressure distribution of the central body and the internal flow path is hardly affected. Therefore, there is no change in the thrust ratios which stay at 0. 97 and 0. 98, respectively. [ABSTRACT FROM AUTHOR]