共查询到3条相似文献,搜索用时 2 毫秒
1.
A turbulent separation-reattachment flow in a two-dimensional asymmetrical curved-wall diffuser is studied by a two-dimensional
laser doppler velocimeter. The turbulent boundary layer separates on the lower curved wall under strong pressure gradient
and then reattaches on a parallel channel. At the inlet of the diffuser, Reynolds number based on the diffuser height is 1.2×105 and the velocity is 25.2m/s. The results of experiments are presented and analyzed in new defined streamline-aligned coordinates.
The experiment shows that after Transitory Detachment Reynolds shear stress is negative in the near-wall backflow region.
Their characteristics are approximately the same as in simple turbulent shear layers near the maximum Reynolds shear stress.
A scale is formed using the maximum Reynolds shear stresses. It is found that a Reynolds shear stress similarity exists from
separation to reattachment and the Schofield-Perry velocity law exists in the forward shear flow. Both profiles are used in
the experimental work that leads to the design of a new eddy-viscosity model. The length scale is taken from that developed
by Schofield and Perry. The composite velocity scale is formed by the maximum Reynolds shear stress and the Schofield-Perry
velocity scale as well as the edge velocity of the boundary layer. The results of these experiments are presented in this
paper. 相似文献
2.
The boundary layer integral method is used to investigate the development of the turbulent swirling flow at the entrance region
of a conical nozzle. The governing equations in the spherical coordinate system are simplified with the boundary layer assumptions
and integrated through the boundary layer. The resulting sets of differential equations are then solved by the fourth-order
Adams predictor-corrector method. The free vortex and uniform velocity profiles are applied for the tangential and axial velocities
at the inlet region, respectively. Due to the lack of experimental data for swirling flows in converging nozzles, the developed
model is validated against the numerical simulations. The results of numerical simulations demonstrate the capability of the
analytical model in predicting boundary layer parameters such as the boundary layer growth, the shear rate, the boundary layer
thickness, and the swirl intensity decay rate for different cone angles. The proposed method introduces a simple and robust
procedure to investigate the boundary layer parameters inside the converging geometries. 相似文献