In order to study the effect of gas content on the internal pressure in hydraulic turbine

CFD technology was used to simulate the flow field in a pump with the specific speed of 845 as turbine

the distribution of gas and the effect of gas content on pressure fluctuation in hydraulic turbine were clarified. Results showed that from volume inlet to impeller outlet

the gas content increased gradually

when the gas content was equal to 02

the gas distribution was not uniform

and in volume outlet and impeller inlet the wake effect was obvious. The gas gathered in impeller outlet

the higher gas rate indicated the more obvious gathering phenomenon. The influence of gas content on the distribution of relative pressure was obvious

the relative pressure of each point in hydraulic turbine decreased with the increase in gas rate. The gas content had little effect on the pressure fluctuation amplitude of the monitored point at the main frequency when the inlet gas content was less than 005

but when the inlet gas content was greater than 005

the effect was obvious. The bigger gas content meant the smaller pressure fluctuation frequency amplitude. In different gas content the main frequencies of pressure fluctuation in turbine volute and impeller were equal to the rotation frequency of the impeller blades.