Assessing the Effect of Uneven Inlet Velocity on the 24 ft Diameter MinwaterCSP Fan Using a Unique Pressure Sensing System

Abstract

An industrial-grade pressure sensing system was designed for installation on the surface of the 24 ft (7.315 m) diameter M-fan that is installed on the MinwaterCSP test facility. The facility has significant cross draft effects due to the proximity of a canal that runs underneath the centre of the facility. This canal causes disturbance of the inlet air flow distribution. Due to the constant rapid change in air velocity and direction with blade rotation, the pressure on the blade fluctuates. The velocity distribution was measured experimentally using the installed anemometers. The uneven inlet velocity distribution led to fluctuations in blade surface pressures, which were measured using the uniquely designed pressure sensing system. The measured results were compared to the results of a Computational Fluid Dynamics (CFD) model of the MinwaterCSP test facility. The CFD simulations consisted of two parts. Firstly a 3-dimensional representation of the facility, which was used to get the velocity distribution data and secondly a 2-dimensional airfoil simulation which was used to obtain the surface pressure distribution on the blade surface. The 3-dimensional CFD model made use of an actuator disk model to represent the effect of the fan. The experimental results showed a higher velocity and relative surface pressure distribution at locations correlating to the location of the canal. The simulation was able to replicate these distribution fluctuations. The results of the experimentally measured fan blade surface pressure at the fan suction side correlated within 9% to those of the simulation results.