Enhancement Of the Surge Margin Of An Axial-Flow Fan Using Inlet Guide Vanes (IGV)

Document Type : Research articles

Authors

1 M.T.C.Egypt Royal Bahraini Air Force.

2 Mechanics Department, Tanta University, Egypt.

3 Head of Aircraft.

4 Armed Forces Mechanics Department Egypt M.T.C., Egypt

Abstract

Improvement of the surge margin is carried out by the stall and surge control methods to allow a wider range of operation. This work shows the improved surge margin of an axial flow fan used as a power fan (which considered as a low-pressure-ratio compressor) in a wind tunnel by implementing an additional row of inlet guide vanes (IGVs) upstream of the rotor blades in order to redirect the entering flow to the suitable incidence angle for the rotor blades. Three different exit setting angles for IGVs row are tested by using a computational fluid dynamics (CFD) model via the commercial program ANSYS. The fan measured data sheet[1] and a baseline case are compared to validate the design point of the constructed CFD model. The fan flow path, the mean line total conditions and all design controlling parameters are determined on the basis of mass, energy and momentum conservation equations. The solution presented is based on the finite volume technique, which is utilized by ANSYS CFX to solve those equations in order to calculate the flow characteristics. The fan surge line is constructed first by the CFD model (that consists of various rotor operating pitch angles for the fan) and the results are compared to the baseline case and found with a deviation of about 3.644%. The IGVs with different setting angles are placed in the CFD model one at a time for all rotor blade pitch angles upstream of the rotor blades and the new surge lines are achieved for each. Finally, the selected control law for IGVs setting angle variation is introduced with an improved surge margin by about 12% and 37.931% for the pitch angles +5° and -15°, respectively.

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