Effect of Air-Gap / Inlet Jet Width and Reynolds Number on Inlet Discharge Coefficient forCircular Air-Turn Bars

Abstract

This study was conducted to provide a preliminary screening of the effect of the flow beneath a rigid stationary web on inlet mass flowrate using the stream function and vorticity approach computed by a FORTRAN program. If there is no web wrapped around a circular air-turn bar, the flow exiting the air-turn bar is similar to the flow through an orifice. The coefficient of discharge will be governed by the coefficient of velocity and coefficient of contraction. The purpose of the study is to determine the effect of air-gap, inlet jet width, and inlet dynamic pressure on the flow between a circular air-turn bar (with air-emitting slots or holes) and the web that causes the inlet mass flowrate to reduce. The test parameters and inlet mass flowrate are normalized to seek the effect of different air-gap/inlet jet width and Reynolds number on inlet discharge coefficient. The effect of viscosity on inlet discharge coefficient is also studied, enable us to determine whether the viscous forces that dominate the airflow in the narrow clearance of the foil-bearing problem applies to the circular air-turn bar. Fundamental knowledge about computational fluid dynamics is sufficient for the reader to understand the theory presented in this paper.