When a gas-turbine engine is in operation, inlet-generated total-pressure distortion can have a detrimental effect on engine’s stability and performance. During the product development life cycle, on-ground wind tunnel tests and in-flight tests are performed to estimate the inlet distortion characteristics. Extensive measures are taken in the preparation and execution of inlet distortion tests. The data pertaining to spatial inlet distortion is recorded using an array of high-response total-pressure probes. The pressure probes are usually arranged in rake and ring arrays as per AIR1419. The data from these probes is used by propulsion system designers to address the effects of inlet distortion on stability and performance, particularly the engine’s sensitivity to inlet distortion. In some instances, the probes can produce inaccurate measurements or no measurements at all, due to a variety of reasons. This may result in a time consuming and costly process of repeating the test. To avoid this, the inaccurate or invalid measurements can be substituted using a variety of statistical techniques during test data post-processing. This paper discusses the results of different interpolation techniques to substitute invalid steady-state total-pressure measurements, evaluated in the context of classical distortion profile data available in AIR1419. The techniques include 1D linear interpolation using only probes data from adjacent rings, 1D linear interpolation using only probes data from adjacent rakes, and bilinear interpolation using probes data from adjacent rings and rakes. Furthermore, the paper evaluates a bilinear interpolation technique with optimal weights obtained from linear regression, that enhances the estimation of invalid pressure values.

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