Hydraulic instability associated with pressure fluctuations is a serious problem in hydraulic machinery. Pressure fluctuations are usually a result of a strong vortex created at the outlet of a runner. The amplitude of the pressure pulsation is different for each operating regime therefore the main goal of this research was to numerically predict pressure pulsation amplitude versus different guide vane openings and to compare the results with experimental ones.
COBISS.SI-ID: 24567079
A pump intake can have an important impact on a pump operation due to production of strong unsteady vortices which may cause air intake problems. Constructing a pump sump model and experimental testing is expensive, therefore numerical simulations are expected to help or even replace the experimental testing in the future. For a small chamber vortex simulation, various turbulence model simulations as well as laminar and Euler simulations were evaluated. The results indicate that the SAS-CC turbulence model might be a good choice for a simulation of a pump intake.
COBISS.SI-ID: 14620950
This paper presents a numerical analysis of flow in a 2 jet Pelton turbine with horizontal axis. The results were compared to the results of a test of the model. A k-? SST turbulent model was used. Free surface flow was modelled by two-phase homogeneous model. Torque on the shaft was then calculated from pressure distribution data. Averaged torque values are smaller than measured ones. Consequently, calculated turbine efficiency is also smaller than the measured values, the difference is about 4 %. The shape of the efficiency diagram conforms well to the measurements.
COBISS.SI-ID: 24543271
The paper presents numerical analysis of the flow in all types of water turbines. A detailed analysis of complete radial and axial turbine is presented. On the basis of numerical results efficiency and cavitation are predicted and compared to the measured results obtained on test rigs in Turboinstitut. The paper presents also numerical analysis of the flow in a two jet Pelton turbine. The predicted efficiency is compared to the measured values.
COBISS.SI-ID: 14940761
Circulating water systems and safety water systems in various power plants use vertical pumps. In the current paper we confirm that Scale Adaptive Simulation (SAS) turbulence model with the curvature correction (CC) factor applied is well suited for such flows. By using a methodology for determining the vortex air core length, the SAS-CC turbulence model results were compared to the experimental data for two selected temperatures. The results show better agreement than the laminar simulations in terms of higher mean value accuracy and lower scattering.
COBISS.SI-ID: 14878742