Investigation of the transient flow turbulence in pipes with leak

The remote leakage detection methods in pressurized pipes, are based on the analysis of the pressure fluctuations during the transient flow. In this regard, practical applications of transient flow can be improved and simultaneously, the destructive effects of transient flow on the pipeline and its equipment would be decreased by studying and understanding the transient flow. In the present paper, it has been tried to analyze the flow behavior and the turbulence parameters during different cycles by modeling transient flow with a leak in two dimensions. The proposed numerical model is based on the finite difference scheme and a flux-corrected transport method is used to eliminate numerical dispersion. In order to study the behavior of turbulence in the flow and its dissipation, the k- turbulence model is coupled with the 2D transient flow model and also the leak effect is added to the steady and unsteady parts of the model. In the presence of the leak in the transient flow, a considerable change is seen in the velocity profile and the turbulence parameters in the flow back and forward cycles. In the initial cycles of the transient flow, the different parameters in the upstream of the leak,
decrease gradually and increase in the downstream of the leak until these two flows reach each other. Later, the turbulence initiates to extend from the near pipe wall into inner layers and the magnitude decreases gradually by passing time.