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Technical Paper

Stator and Support Arm Aerodynamic Performance for Automotive Engine Cooling Fans with Realistic Inlet Conditions

2007-04-16
2007-01-0769
The influence of a typical stator and support arm on the performance of an automotive engine cooling module is evaluated. Measured lift (CL) and the drag (CD) coefficients are compared for a typical stator and support arm under real unsteady inlet conditions. These inlet conditions are based on Laser Doppler Velocimetry (LDV) data taken in the flow downstream of an automotive cooling fan. The quality of the experimental results is assessed upon comparison with the well-established flat plate data. It is found that inlet conditions dramatically affect the aerodynamic performance of both the stator and the support arm. A suitable range of inlet conditions on which to base the design is presented. The second objective of the current study is to establish accurate numerical simulation guidelines for future fan designs. Various turbulence models are evaluated based on comparison with experimentally measured data for a stator and a support arm at various angles of attack.
Technical Paper

Experimental Study of Automotive Cooling Fan Aerodynamics

2007-04-16
2007-01-1525
Plenum chamber performance and Laser Doppler Velocimetry measurements on two different fan types show the impact of the vehicle engine on automotive cooling fan-specific aerodynamic performance. The pressure loss caused by the blockage plate is proportional with the flow rate and inversely proportional to blockage distance. LDV measurements show that the blockage plate causes a reduction in the flow rate, an increase in the reverse flow near the fan hub, and a dramatic increase in the radial flow. The relation between blockage-to-fan distance and fan performance was established. It is found that the pressure change follows a quadratic function, but the coefficients are fan specific
Technical Paper

Stator Performance for Automotive Cooling Fans with Unsteady Inlet Conditions

2006-04-03
2006-01-1038
The choice between using stators or support arms downstream of an engine cooling fan depends on the lift and drag forces. A transient, Computational Fluid Dynamic (CFD) simulation was performed of a stator configuration. Results for an unsteady (sinusoidal) inlet condition, based on Laser Doppler Velocimetry (LDV) data of a flow downstream of an automotive fan, are compared to steady inlet conditions. Vortex shedding and suction side separation were observed with a steady inlet condition. Due to the vortex shedding the lift coefficient fluctuated. The mean lift coefficient was 68% lower than the published data used for design. The mean lift coefficient observed was similar to what was expected from a cambered plate of 2% camber at the same angle of attack. The performance of the stators under unsteady inlet conditions was different than under steady inlet conditions and therefore steady flow velocities are not an effective input to design.
Technical Paper

Effect of Fan Hub Configuration on the Cooling Airflow through Electric Motors in Engine Cooling Fan Systems

2006-04-03
2006-01-1037
Typical automotive engine-cooling fan assemblies include an electric motor having a driveshaft coupled to a fan. The typical fan includes a hub, which extends from the driveshaft to the root of the fan blades. Radial ribs are incorporated within the hub to stiffen the fan structure. The fan hub including the ribs pulls cooling air through the motor, thus preventing it from overheating. Experimental tests and computational fluid dynamics (CFD) simulations have been carried out to investigate the effects of fan hub configurations on cooling airflow through the electric motor in automotive cooling fan systems. It has been found that radial ribs on the fan hub have significant effects on drawing cooling air through the motor. The comparison of the simulation results with the pressures measured in laboratory experiments show good agreement.
Technical Paper

Downstream Blockage Corrections of Automotive Cooling Fan Module Performance

2009-04-20
2009-01-0175
A novel, simple and rapid method for predicting the performance effects of blockage downstream of an automotive cooling fan is presented. Fans are often tested without downstream blockage and, thus, the performance is considerably different when the fan is mounted in a vehicle as part of a cooling system. An easy to use tool is needed that can quickly predict fan performance modifiers. The suggested approach is able to predict the significant effects of a blockage behind the fan. Two fans were analyzed with this new method. Comparison charts between tests and predictions showed good agreement over a range of blockage distances. Based on the results the method is considered beneficial for initial design procedures. Although the agreement was poorer at very close separation distances such small gaps are less commonly utilized in practice. Further work is needed to include those distances in the present model.
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