Flow characteristics of gas flow through the orifice attached to a pipe end.

This paper describes the mass flow characteristics of free discharge through an orifice. Experiments are carried out to clarify the flow difference between the conventional pipe orifice and the pipe end orifice presented. The results are plotted by introducing λ which is the ratio of real flow rate to the flow determined by using the ASME or JIS regulated value of the pipe orifice into the pipe end orifice case. The experimental results show that the conventional regulated relations of the pipe orifice can be applied correspondingly to the case of this pipe end orifice in subsonic flow regime. The effect of the down-stream pipe length on the flow measurement error, and the effect of an obstacle placed at the free discharge region of the jet on the error are also examined and discussed.