Test Rig Effect on Performance Measurement for Low Loaded Large Diameter Fan for Automotive Application

Abstract

Large diameter fans with low solidity are widely used in automotive application for engine cooling. Their designs with small chord length help reducing the torque on the electrical motor and provide a good aerodynamic compromise between several operating conditions, some of these being at high flow rate. Their global performances are measured according to the ISO standard DP 5801, which allows comparison of results from different facilities. However, some variations in global performances are observed when considering results from two different test rigs. On a fan selected for the purpose of this study, up to 6 % of efficiency is lost on the worst case. As efficiency is more than ever a key factor to select a component, some experimental and numerical investigations were conducted to analyze the fan behavior on each facility. Two sets of measurement and simulation are performed and compared. Geometries considered for the domain of computation include the test rig plenum, the torquemeter, the ground and a large domain for the atmospheric conditions. The exact fan geometry with tip clearance and under-hub ribs is also considered. Numerical results show in both cases a good agreement with experiment when convergence is reached and for low flow rate when computations are switched to unsteady mode. Comparisons show that simulations are able to capture the different fan behaviors depending on the configuration and those efficiency losses previously observed are correctly predicted. These results are further analyzed to perform some post-processing. Blade loading remains identical for both cases but disparities appear in the wake and its interaction with the surrounding. Tiny details that are often neglected during experiment and/or simulation appear to be the cause of slight variations. Position of the torquemeter and shape of the plenum are among the parameters that varies and that have cumulative effects. Efficiency being a ration of pressure and torque, variations are rather important. Finally, these results are discussed in terms of rules for conception and a new geometry less sensible to loss of efficiency is proposed.

Effect of Blade Curvature on Fan Integration in Engine Cooling Module

“…Each device (BW fan with or without exchanger, FW fan with or without exchanger) was tested on the aerodynamic bench at the La Verrière R&D site (France). This bench meets ISO Standard DP 5801 [13] and was presented in [14]. The static pressure is measured as the difference between the atmospheric pressure and the static pressure in the bench plenum (see Figure 3).…”

Sampling strategies for metamodel enrichment and automotive fan optimization

“…As presented in [3], performance predictions for the DoE are obtained, thanks to RANS simulations with the commercial code CCM+, using polyhedra meshes and an accurate description of the test rig (figure 4). The simulation process takes one hour of meshing (a new mesh is produced for each geometry), and requires between 4 to 8 wall clock time with 196 CPU (depending on the convergence).…”

“…Mesh parameters are kept constant from one geometry to the other in order to minimize discrepancies. An accuracy assessment is provided in [3], and allow us to determine the mesh size above which variations remain below 1%. About 20 millions polyhedra are used, mainly concentrated in the rotating domain (15 millions).…”

Influence of Swept Blades on Low-Order Acoustic Prediction for Axial Fans

“…Blade sweep is considered as a classical technique in order to mitigate the far-field emissions as well as to enhance the aerodynamic efficiency [5]. In the automotive field, low-speed cooling fans [6] are used to cool down the engine of the car by extracting hot air out of heat exchangers [7]. Several noise-generating mechanisms of tonal and broadband nature occur in this application [8], where backward-swept and forward-swept propellers are often employed [9].…”