Numerical simulation of nozzle flowfield characteristic of orifice flow generator

For orifice high-temperature gas jet, a two-dimensional axisymmetric model of unsteady free jet was established. The flow of high-temperature turbulent gas was simulated by using CFD software FLUENT. The calculation results show that the flow field parameters such as temperature and velocity along the axial direction almost have no changes at upstream of the flowfield, but there is a certain location where greater attenuation gradient appears. The temperature and velocity along the radial direction have the single peak distribution, and with the increase of radial distance, the values decrease. The disturbed radial regions expand with the passage of time and the increase of axial distance. The distributions of total pressure and density have the same shape. Because of the resistance of environmental gas, the jet head has a return flow phenomenon, and as time goes on, the isobaric surface of the jet head has a shape of ellipsoid.