A Study on Unsteady Flow Characteristics and Lateral Force of Conventional Bell-type Nozzle

A numerical study on unsteady flow characteristics of conventional bell-type nozzle has been conducted. In the computations axisymmetric full Navier-Stokes equations have been solved. AUSUM-DV scheme is used for convection terms. Central difference is used for viscous terms and LU-ADI scheme is used for time integration. Baldwin -Lomax turbulence model is also used in the computations. The nozzle configuration of a truncated perfect nozzle is selected for computations. The starting process of the nozzle is sialylated numerically and unsteady flow characteristics and flow separation and reattachment of the flow are observed carefully. Quite unsteady flow patterns are observed and in the starting process and FSS (Free shock separation) pattern and RSS (restricted shock separation) pattern are also observed. The surface pressure distributions of RSS show locally higher pressure region might generate lateral force of the nozzle in the starting process when asymmetrical flow separation occurs.