Cavitation Flow Through an Axial Inducer CFD Simulation, ANSYS Fluent Tutorial

This simulation is about cavitation flow through an axial inducer via ANSYS Fluent software. We perform this CFD project and investigate it by CFD analysis.

The cavitation phenomenon is one of the phenomena in that vapor bubbles are formed in the part of the fluid whose pressure is low. Sometimes there is a misconception that the only reason for this phenomenon and the formation of steam bubbles is because the liquid pressure reaches the vapor pressure (P_v).

However, various other factors and parameters cause this phenomenon to occur. For example, speed is one of the useful parameters in creating this phenomenon. The phenomenon of cavitation can cause many problems, including corrosion. Corrosion is very evident in the water pump.

We identify this phenomenon by the sound produced and the mechanical vibration produced. There are several ways to reduce this occurrence. One of the simplest methods is to increase the pump’s inlet pressure by reducing the distance between the pump and the tank.

Another way is to reduce the pressure drop and flow turbulence. Today, with the industry’s expansion, the need for pumps with smaller sizes and higher speeds is felt more. Therefore, it is necessary to improve the suction performance of pump impellers.

Inducers are essential components installed in front of the main impeller to achieve higher suction performance in the pump and rotate at the same impeller speed. The inducer can increase the inlet pressure to the pump impellers and improve the pump’s suction performance.

One of the most important phenomena that should be considered in pumps is the phenomenon of cavitation. One of the important reasons that inducers are used in pumps is to reduce cavitation.

The geometry of the present model is drawn by Design Modeler software. The model is then meshed by ANSYS Meshing software. The model mesh is unstructured, and 938174 cells have been created.

Cavitation Method

In this simulation, the Frame Motion method is used to define the rotational velocity of the inducer. In fact, the rotational speed equal to 15000 rpm is defined for the fluid around the inducer blades.

Also, to investigate the phenomenon of cavitation, a Multiphase Model should be used; Because the phenomenon of cavitation is caused by the phase change between liquid and vapor.

To define the multiphase model, the VOF model has been used. The characteristic of this model is that the separation boundary between the two phases is completely distinct. The liquid is defined as the primary phase and vapor is the secondary phase.

Cavitation Conclusion

After simulation, the contours of velocity, pressure, and mass fraction of liquid and vapor are obtained. Also, streamlines around the inducer are obtained. The results show that as the fluid enters the inducers, the pressure increases.

If this inducer is connected to a pump, it is the output pressure and the maximum inducer pressure that the impellers have. The suction pressure at the back of the inducer has increased, which improves the pump’s suction performance.

Velocity contours and Streamlines show that the velocity near the inducer has its maximum due to the angular velocity in this part. Also, the volume fraction contours show that cavitation has decreased.

Also, the velocity contours show that cavitation has decreased because the amount of water on the inducer is more than vapor.