INFLUENCE OF THE SHAPE OF THE IMPELLER BLADE TRAILING EDGE ON SINGLE AND TWO-PHASE AIRWATER FLOWS IN A CENTRIFUGAL PUMP
Abstract
In this study, the performance of a radial-type centrifugal pump was investigated for different single and two-phase flow conditions to evaluate the influence of the shape of the impeller blade trailing edge. For that purpose, two geometrically similar semi-open impellers with two common blade trailing edge profiles were manufactured and experimentally compared, considering a round trailing edge (RTE) and a trimmed trailing edge (TTE). The impellers and pump casing were made of transparent acrylic glass to allow visualization and recording of the two-phase flow regimes by a high-speed camera. Additionally, 3D URANS numerical single-phase simulations were performed for the whole pump geometry to understand the performance changes between the two impeller designs. The standard moving-mesh approach combined with the k – ω SST turbulence model was used to simulate the pump flow. In the experiments, the hysteresis effects were studied by incorporating two different procedures to set the desired operating conditions. The pump performance was measured and analyzed for both constant gas volume fractions and constant air flow rates at the pump inlet. The results show that the pump with TTE impeller has considerably lower performance compared to the RTE impeller for single-phase as well as most of the two-phase flow conditions. The reason for this lower performance could be revealed by the numerical simulations, where the interaction between the TTE impeller and the volute tongue led to a bigger separation. Furthermore, the experiments show that the TTE impeller has a much larger surging region compared to the RTE impeller. The reason is that the TTE impeller is more prone to gas accumulation within blade channels at lower gas volume fractions due to its lower performance. This limits its working range further, particularly at 5 % gas volume fraction. Comparing different experimental procedures, hysteresis effects were observed for the RTE impeller only for gas volume fractions between 4 and 5 %, while the TTE impeller has increased hysteresis effects for gas volume fractions between 3 and 5 %. Finally, two-phase flow regime maps were generated and associated with the pump performance. Based on the results shown in this study, the round trailing edge is always recommended to ensure higher single and two-phase performances, lower gas accumulations, and more limited surging and performance hysteresis.
Description
LectureCollections
Citation
Mansour, Michael; Thévenin, Dominique; Parikh, Trupen (2020). INFLUENCE OF THE SHAPE OF THE IMPELLER BLADE TRAILING EDGE ON SINGLE AND TWO-PHASE AIRWATER FLOWS IN A CENTRIFUGAL PUMP. Turbomachinery Laboratory, Texas A&M Engineering Experiment Station; Texas A & M University. Libraries; Texas A & M University. Libraries. Available electronically from https : / /hdl .handle .net /1969 .1 /196803.