Studies of flight-velocity effects on near-field and intermittent properties of a subsonic jet

The flight velocity effect on a cold jet flow is numerically predicted by the improved delayed detached eddy simulation (IDDES) with a modification to the grid length scale, mainly focusing on the near-field flows and intermittency properties in the jet centerline region. First, the modification in IDDES is validated using three meshes and available measurements. This method can reduce the modeled eddy viscosity effectively and improve the performance of original IDDES. Then, the flight velocity effects on the mean flow, turbulence, and intermittency are studied. From the results, the fluctuation intermittency near the end of potential core is caused by the intrusion of turbulent shear-layer structures into the jet core. When the flight velocity increases, the intermittency factor in the jet centerline region is reduced, and its peak moves downstream. The skewness and kurtosis factors perform in a similar manner. (C) 2019 Elsevier Ltd. All rights reserved.