Using shape memory alloys for improving automotive fan blade performance: experimental and computational fluid dynamics analysis

Abstract

In recent years, a considerable effort has been devoted towards the application of advanced techniques for turbomachinery efficient fluid dynamic control during operations. A novel strategy to dynamically modify and optimize the performance during operations takes advantage of shape memory alloys properties. Experimental and numerical analyses on a morphing polymeric blade for an automotive axial fan are presented. The blade shape change was achieved by shape memory alloys strips, thermomechanically treated, embedded in the blade and thermally activated by hot air stream flow. Measurement of fluid temperature, blade surface temperature pattern and three-dimensional shape change of the blade during activation was performed by means of an innovative image analysis technique in a purpose-built wind tunnel. Computational fluid dynamics numerical simulations were performed to study performance variations and three-dimensional fluid dynamic behavior of the fan originated from the shape memory effect.

Analysis of the Aerodynamic and Structural Performance of a Cooling Fan with Morphing Blade

“…As shown in the extensive fluid dynamic and performance analysis reported in [11,17] the fan with the activated blades shows a higher pressure coefficient at the same flow coefficient. In particular, this performance gain is equal to 3 % at the best efficiency point of the fan with the activated blades.…”

Analysis of the Aerodynamic and Structural Performance of a Cooling Fan with Morphing Blade

“…For this reason, the operating range of the activated blade is limited to a flow coefficient higher than 0.42. As shown in the extensive fluid dynamic and performance analysis reported in [11,17], the fan with the activated blades shows a higher pressure coefficient at the same flow coefficient. In particular, this performance gain is equal to 3% at the best efficiency point of the fan with the activated blades.…”

“…The suction side of the blade is reported first as the view of the camera and then as the point cloud (used for the subsequent solid modeler reconstruction) provided by the Kinect sensor. An evaluation of the accuracy of the Kinect sensor to detect the blade surface is reported in [17] and a full description of the experimental apparatus and its thermal performance behavior can be found in [18]. The SMA thermal activation and the resulting blade deflection were achieved by (i) a heating ramp and (ii) a cooling ramp, described as follows.…”

“…Starting from the scanned blades and the solid modeler reconstruction extensively reported in [17], two numerical domains were generated in order to analyze the performance of the fan by means of CFD numerical simulations in non-activated and activated conditions. The CFD analyses reported in this paper are taken from previous works [11] and, for the sake of completeness, this paper reports the numerical model setup and the cooling fan performance, though additional information can be found in [11].…”

On the design strategies for SMA-based morphing actuators: state of the art and common practices applied to a fascinating case study

“…In addition, such a model lays the foundation for a more detailed and accurate description of the SMA-based blade actuator. 130 According to Sˇittner, 131 simulating the behavior of SMA-based systems is especially valuable in the light of (i) the materials design, (ii) the control input/composite response relationship (iii) the prototype applications and (iv) the online control functions. Based on these considerations, the modeling should provide the parameters for most suitable materials as well as for proper fabrication procedure in order to fully evaluate and understand the functionality of the prototype and its responses (bending stiffness, shape changes, deflection, etc.).…”