Development of Mach 3.6 water cooled facility nozzle

This paper describes the design and development of Mach 3.6 water cooled facility nozzle using both analytical and computational approaches and highlights the subsequent experimental tests which showed that the results were in agreement with the design intent. The nozzle has been designed based on method of characteristics to get uniform Mach number at the exit plane. Nozzle operating conditions are 25 bar total pressure, 1700 K total temperature and 30 kg/s total mass flow rate with an exit area of 350 mm x 350 mm. In addition to the above effort, computational studies were made to predict and validate the flow in the Mach 3.6 nozzle that was designed to produce a uniform supersonic flow. ANSYS-Fluent commercial code was used to compute the flow through a 2-Dimensional convergent divergent nozzle. The geometry and grid were generated using the pre-processor (GAMBIT). In order to capture the boundary layer efficiently, fine grid was generated near the wall. The conservation equations were discretized with 2nd order upwind scheme. Three different mesh sizes were taken for the grid independence study and five different turbulence models were used for assessing the appropriate model. 2-D steady state RANS (Reynolds Averaged Navier-Stokes) equations were used for computation. Among the models investigated, SST k- and RNGk- turbulence models were found to give better agreement