![]() The paper will be presented at the 2016 SAE Commercial Vehicle Engineering Congress.Our high-end radiator fan shrouds are fully designed in-house and manufactured locally our process starts by finding an original, or a popular aftermarket, radiator to scan in with our high-end 3D Scanning equipment once we have a fully digitised copy of the radiator, we then go about selecting an appropriate cooling fan based on airflow and under fan surface area. This article is based on SAE technical paper 70 authored by Prasad Vegendla and Tanju Sofu of Argonne National Laboratory Rohit Saha, Mahesh Madurai Kumar, and Long-Kung Hwang of Cummins and Steven Dowding of CD-Adapco. Further evaluation is ongoing to maximize the cooling air mass flow. The airflow around the optimized edges was much smoother, as the edges act to reduce pressure losses and ultimately led to a higher mass flow rate through the heat exchanger. The improvement was primarily due to smoothing of the fan-shroud surface edges compared to the sharp edges in the original model. The optimization process resulted in a 1.4% increase in cold airflow with optimization of the fan-shroud surface. In underhood compartments, stagnant flow zones are common between fan and engine block. The highlighted areas show the modified/optimized edges that provide lower pressure loss and higher mass flow rates through the heat exchangers.įigure 2 reveals that the velocity flows away smoothly from the fan. Figure 1 shows the original shroud surface, which consists of sharp edges when compared to the morphed/optimized surfaces. The process of solving for the primal solution, Adjoint solution, Adjoint sensitivities, and mesh deformation was repeated 20 times to generate a cumulative displacement of the control points and the shroud geometry to increase the mass flow rate through the radiator. The morphing of the control points resulted in deformation of the mesh, and ultimately of the underlying fan-shroud geometry. The scaled sensitivity vector values were then used as displacements for the morpher. The vectors were scaled to limit the maximum displacement of the morpher and produce a smoother transition to the optimal shape. The solution to the Adjoint was used to calculate sensitivities of the primal flow to changes in control point position, resulting in a field of Adjoint sensitivity vectors on those points. ![]() Using the converged primal solution, a cost function of mass flow rate through the radiator with respect to fan-shroud position was solved on predefined control points near the fan-shroud surface to obtain a solution to the Adjoint equation. The primal solution was driven to convergence by successively increasing the coupled solver Courant number. A moving reference frame approach was used to simulate the effects of the moving geometry. The solution was solved steady-state, using a coupled solver approach and k-epsilon turbulence. First, a well-converged primal solution was obtained on a polyhedral mesh. The optimization process was accomplished using the Adjoint solver and mesh morpher in STAR-CCM+. Adjoint optimization is an efficient sensitivity analysis method for aerodynamic shape and pressure drop evaluation. ![]() To optimize the fan-shroud shape to maximize cooling air mass flow rates through the heat exchangers, researchers from Argonne National Laboratory, Cummins and CD-Adapco used the Adjoint approach to optimization. In heavy-duty trucks, the cooling package includes the heat exchanger, fan shroud and fan. ![]() The vehicle underhood compartment consists of the engine and cooling package. Shroud design affects both the airflow and the noise generated by the fan. Fan shrouds funnel cooling air, which is sucked by the fan and passed through heat exchangers. Fan and fan-shroud design is crucial for underhood airflow management. Tighter emissions requirements and underhood packing due to higher power demands from engines necessitate more optimized cooling packages.
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