The paper describes experiments carried out in the cavitation tunnel with the rectangular test section of 150 x 150 x 500 mm and the maximum test section inlet velocity of 25 m/s. These experiments have been aimed to visualize the cavitation phenomena as well as to quantify the erosion potential using pitting tests evaluated during the incubation period for the cast-iron prismatic hydrofoil with the modified NACA profile. A bypass section installed in the tunnel has allowed to measure the nuclei content in the inlet flow to the test section using the acoustic spectrometer. The measured data have been compared with the CFD analysis of the cavitation phenomena on the hydrofoil as well as the numerically determined location and magnitude of the first calculated collapses of the cavitating bubbles with a good agreement. • (1) 6,*0$ 5HVHDUFK DQG 'HYHORSPHQW ,QVWLWXWH -DQD 6LJPXQGD /XWtQ PLODQVHGODU#VLJPDYYXF] PDUWLQNRPDUHN#VLJPDYYXF] PLFKDOY\URXEDO#VLJPDYYXF] )DFXOW\ RI 0HFKDQLFDO (QJLQHHULQJ 7HFKQLFDO 8QLYHUVLW\ RI /LEHUHF +iONRYD /LEHUHF PLORVPXOOHU#WXOF]EPJ Web of Conferences , 010 (2012)

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Abstract. This work deals with the experimental and numerical investigation of cavitating and noncavitating flow inside a mixed-flow pump and its influence on performance curves of this pump. The experimental research has been carried out in the closed horizontal loop with the main tank capacity of 35 m 3 . The loop is equipped with both the compressor and the vacuum pump capable of creating different pressure levels while maintaining constant volume flow rate. Pump investigated in this project has been equipped with transparent windows, which enabled the visualization of flow and cavitation phenomena for a wide range of flow conditions. A comprehensive CFD analysis of tested pump has been done both in the cavitating and noncavitating regimes. The ANSYS CFX commercial CFD package has been used to solve URANS equations together with the Rayleigh-Plesset model and the SST-SAS turbulence model. Both the experimental research and the CFD analysis have provided a good illustration of the flow structures inside the pump and their dynamics for a wide range of flow rates and NPSH values. Flow and cavitation instabilities have been detected at suboptimal flow rates which correspond to increased values of noise and vibrations. The calculated results agree well with the measurements.

This paper deals with the numerical analysis of flow in a complete hydraulic system representing the pump station including the influence of the free water level. Particular attention is paid to the discharge object with overflow, which is characterized by the critical flow across the crown of the overflow wall. All basic calculations were accomplished by means of the commercial software ANSYS CFX and ANSYS Fluent with the SST turbulence model. As the flow in the discharge object represents the most interesting part of the results, additional numerical simulations of flow just inside this object were carried out with the DDES scale resolving simulations. Basic calculations inside the complete pump station passage gave surprisingly steady water level in both the intake and discharge objects. They also provided a good picture of the distribution of water velocity close to the water level and corresponding height of water level above the overflow wall crown. DDES simulations indicated a periodically formed vortex on a water level behind the overflow wall crown, with a (not very distinct) Strouhal number about 0.3.

Abstract. This paper describes the preparation of the experimental setup and the results of the CFD analysis for the investigation of the unsteady cavitating flow around a prismatic NACA 2412 hydrofoil at different flow conditions. The experimental research is carried out in the cavitation water tunnel located in the Centre of Hydraulic Research in Lutín. The tunnel is integrated into the closed horizontal loop of the hydraulic test rig. The transparent test section provides a full view of the flow around the hydrofoil. The hydrofoil incidence angle is fully adjustable. Two variants of hydrofoil of the same geometry have been designed. One variant is equipped with pressure tap holes for the measurement of the static pressure, and the other variant is covered with a grid of five PVDF films, fully integrated in the hydrofoil. The PVDF films enable to measure the impact forces exerted on the hydrofoil surface by the collapsing cavitation structures. The high-frequency pressure oscillations downstream of the hydrofoil trailing edge are measured using the PVDF hydrophone. The cavitating flow is visualized using two simultaneously operating high-speed cameras providing the top and side views of the flow. A preliminary CFD analysis using the ANSYS CFX package helped to determine the flow regimes for the experimental study. The obtained CFD results agree well with the preliminary measurements.