Airflow Inside the Air Intake Room Description

The present simulation is about airflow inside the air intake room for a gas turbine via ANSYS Fluent. In this project, an air intake room is designed for gas turbines. An air intake filtration system is essential for the successful operation of a gas turbine.

This system protects the gas turbine from dust particles in the ambient air; Because these suspended particles in the air cause destructive phenomena such as erosion, fouling, collision, etc. This system consists of some rows of parallel plates in the input section.

The present geometry is designed in a 3D model via SpaceClaim. The computational zone is the interior of the air intake room for a gas turbine. Inside this air intake room, some rows of parallel plates with angle of 3 and 6 degrees around the Y axis, are used. The air enters the domain through the narrow inlets with 0.06 meters width and its velocity is 5 m/s. Its outlet is in the side part of the end of the system. The meshing of the present model has been done via ANSYS Meshing and the number of produced structured elements equals 13,103,505 and 13,867,650 for the first and second case respectively.

Methodology

In this simulation designing an air intake room with efficient input section configuration is considered so that the air inlet is purified as much as possible. The process of purification is simulated via Discrete Phase Model (DPM) in which the solid particles (SiO2) with max diameter of 0.002 meters are injected from inlet surfaces entering with air flow. Note that the particles volume fraction is considered 8% of the air. The plates walls are considered as trapping walls in order to trap the particles and the other walls should be set as reflect walls not to trap the particles.

Design Improvement and Conclusion

To observe the effect of intake configuration on purification, we designed two cases. The first one including parallel plates with 3 degrees angle around the Y axis and second one containing parallel plates with 6 degrees angle around the Y axis. The main goal is to investigate how purifying is done via first one and how to improve this process by increasing the angle of plates around the Y axis in order to see if the more particles are trapped. We monitored the number of  tracked and trapped particles during the simulation to see how purification is done. In the first case among the 63000 tracked particles, 54,472 particles were trapped which means that the purification process simulated by DPM model has about 80% efficiency. But in the second design, by increasing the angle of plates, this efficiency  reaches to 88%.

As one of results, we got the DPM concentration in inlet and outlet which was 0.1527 and 0.00012(kg/m3) respectively in the second case that means we have obtained clean air so that it can enter the gas turbine. Also the outlet velocity increases to 17(m/s) because of the small outlet area.

After calculation, 2D and 3D contours related to pressure and velocity are obtained. The contours show that when airflow passes through the space between the plates at high speed, the air pressure decreases after colliding with the parallel plates.