The intentional disruption of airflow with the goal of modifying lift or drag characteristics is common in low speed aerodynamics applications (i.e. aerospace, automotive, wind energy, etc.). This effect can be adapted for changing operational or environmental conditions via the use of rigid rotating panels (e.g. control surfaces on wings), the actuation of which can require relatively high torques, though often over limited angular range. Common actuation options include hydraulics, which may be used in large aircraft, or geared electric motors in smaller applications. Shape memory alloy (SMA) torsional actuators provide very high torques at low installation volume and mass, with rotational capabilities compatible with most airflow manipulation techniques.  

In this work, a novel SMA torque tube-actuated split-flap prototype was designed, fabricated, and tested for low speed aerodynamic applications. The design focused on accurately recording and controlling the flap rotation in a flow environment. This control was achieved through calibrating a PID control for the heat input to the SMA torque tube.  The design also accounted for materials used to reduce thermal conductivity between the torque tube and flap, and thus thermal losses to the environment via convection. Torque, flap temperature, and deployment level were monitored throughout wind tunnel testing. Thermal imaging and hot wire anemometry were also used to visualize the temperature and turbulence profiles of the flap.  Peak deployment of 75° from horizontal was achieved under flow speeds of 40 m/s, with peak torque well below the limits of the SMA torque tube. Hot wire anemometry mapped the spatially variable increase in downstream turbulence due to flap deployment.  These results indicate that an SMA torque tube has the potential to replace electric motors for actuation in low speed aerodynamic applications.


Design, Fabrication, and Experimental Demonstration of an Shape Memory Alloy-Based Adaptive Flow Modification System

Division / Sponsors: 
Aerospace Division

Paper Proceedings: https://asmedigitalcollection.asme.org/SMASIS/SMASIS2020/volume/84027

SMASIS2020 - Virtual Conference

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.