A STUDY INVOLVING THE FLOW PATTERN COMPARISON OF A PIV EXPERIMENT WITH CFD SIMULATION, FOR THE FLOW WITHIN A CENTRIFUGAL PUMP

Computational Fluid Dynamics (CFD) modeling software is increasingly being used as the tool of choice for analyzing the flow details and integrated performance of turbo-machinery products. In fact, the use of CFD is rapidly transitioning from a verification tool to an upfront design-enabling & optimization tool. Experimental validation of computational simulation is essential to ensure an acceptable degree of reliability and relevance of the simulated results to real world performance. While CFD has been rigorously validated for numerous simple physics cases like single-phase flow, more complex physics applications, e.g., those involving multi-phase solid-liquid flows, require more elaborate and thoughtful means of validation. In this context, a study was undertaken to review Particle Image Velocimetry (PIV) as a means of validating more complex CFD cases and to contrast the findings with those obtained from CFD simulation. PIV offers a new possibility for flow visualisation in turbo-machinery passages, in contrast to traditional methods like flow probing or hot-wire anemometry, which can be a very challenging proposition in the rotating domain of a turbo-machinery blade system. This paper discusses the first phase of this work, which was limited to single-phase flow studies, with the intent to follow up further with multi-phase flow studies. A specially designed fractional horsepower centrifugal pump is used as a test subject to analyze all possible parameters of the flow field using PIV and the result is then compared with the CFD simulations of the same model. The results show a reasonable match in the flow patterns obtained by the two alternate methods, although significant differences are apparent too. In conclusion, each method has its own place in the context of turbo machinery flow studies.