Case Study: ARA

The Smith Institute helped ARA to develop a new algorithm to interpolate wing pressure data from wind tunnel tests.

The Aircraft Research Association (ARA) was set up in 1952 as a wind tunnel test centre for the UK aircraft industry and currently provides a wind tunnel model design, manufacture and testing and computational fluid dynamics capability to an international customer base. To ensure they remain at the forefront of aerodynamic testing, ARA aim to reduce the duration of the overall testing cycle whilst maintaining the high quality of output data for their clients.

In wind tunnel testing of aircraft wings, pressure is measured at a large number of tapping points on the wing surface. Efforts to reduce the duration of the overall testing cycle are constrained by the time taken to instrument the surface of the wing. The Innovation and Technology Group at ARA are exploring advanced measuring techniques, including the use of fewer pressure tapping points. To maintain output data quality with fewer pressure tappings, ARA required help to develop an appropriate interpolation algorithm.

The Smith Institute developed a new four-dimensional interpolation algorithm beyond the existing capability. The new algorithm handles the evolution of shock discontinuities and uneven spacing between pressure tapping points. This new capability will enable ARA to (1) reduce the number of pressure tappings without compromising output data quality and (2) provide enhanced visualisation of results for their clients.

Dennis Stanniland, Chief Aerodynamicist at ARA said, “The Smith Institute provided ARA with high quality mathematicians who were able to understand the complexity of the problem and provide an algorithm which uses the variation of surface pressure distributions with Mach number and incidence to enhance the quality of the interpolated pressures at a specified test condition.

“Implementation of this data processing routine into wind tunnel testing will permit ARA to reduce the cost and time taken to manufacture a high speed wind tunnel model by approximately 20% and will enhance the visual presentation of the measured pressure data to the client.”