Applications of a simulation environment during wind tunnel testing

Abstract

There is a distinct parallel between software requirements for hardware in the loop simulation and dynamic wind tunnel testing. Timing, hardware interface, and usability are key factors in overall system quality. A reconfigurable PC-Based simulation environment running under the Windows family of operating systems met timing requirements needed for dynamic testing and was selected to perform data acquisition, processing, and display tasks in two different efforts. As expected, the application of the software was a success. The reconfigurable structure of the software allowed for the quick design and implementation of software for each test. This paper provides a discussion of the software chosen for use during the wind tunnel testing with primary focus on simulation loop timing, and hardware interface. In addition, the paper presents details pertaining to the specific application of the software in the two wind-tunnel testing efforts. Introduction A typical wind-tunnel test to collect aerodynamic forces and moments consists of a test article, force and moment measurement device, model support (rig), signal conditioners, data acquisition and recording devices, and data monitor. Additional components of wind-tunnel test apparatus can be rig controllers, model actuators, and a variety of tunnel state monitors. As once would expect, the specific objectives of test dictate the complexity of the test setup. For example, dynamic wind tunnel testing requires the test article to be subject to a rotation and/or translated motion where position data must be synchronized with the acquired force and moment data. The resulting data must then be reduced and displayed for test engineers' inspection. The apparatus and data requirements for dynamic wind tunnel testing are not unlike those of realtime hardware in the loop simulations. Like real-time hardware in the loop simulations, overall system timing and communication are of the utmost importance. Once received the data must then be processed and provided to the pilot or test engineer. In hardware in the loop situation, the pilot responds to stimuli such as graphical displays or motion, whereas the test engineer and controllers respond to data reduced and provided in a timely manner. Given the parallel between hardware in the loop simulation and dynamic wind tunnel testing, common tools should be relevant to each application. The remainder of this paper provides details pertaining to two such applications. A discussion of components and functionality of the selected simulation environment is presented in addition to information about the specific application of the environment in each of the tests.