The Use of Holographic Interferometry for Turbomachinery Fan Evaluation During Rotating Tests

Abstract

Holography has been developed by Rolls-Royce as a technique for routine use in the evaluation of fan designs for aeroengines. It is used to investigate both aerodynamic and mechanical behavior of the rotating fan. Holographic flow visualization provides clear, three-dimensional images of the transonic flow region between the fan blades. Flow features such as shocks, shock/boundary layer interaction, and over-tip leakage vortices can be observed and measured. Holograms taken through an optical derotator allow vibration modes of the rotating fan to be mapped during resonance or flutter. Examples are given of the use of both techniques at rotational speeds up to and in excess of 10,000 rpm. Holography has provided valuable information used to verify and improve numerical modeling of the fan behavior and has been successful in evaluating the achievement of design intent.

High-Speed Photography and Digital Optical Measurement Techniques for Geomaterials: Fundamentals and Applications

“…The early applications of HI were associated with deformation measurements of a lathe, vibration modes of turbine blades or propellers, non-destructive testing of rubber tires, the SIF of cracks, holographic photoelasticity, and mechanical behaviour of materials (Chia et al 1984;Hariharan and Oreb 1986;Qin 1981;Stetson and Powell 1965;Yu-wen 1979). Later some pioneering work in HI improvement and applications in mechanical engineering and biomechanics were also published (Parker and Jones 1988;Sharma et al 1993;Tieng and Lai 1992;Trolinger and Hsu 1993). The principle of HI is to obtain an interference pattern between two holograms of the same object, where the first is a reference state and the second is made on the same photographic film after the movement has occurred.…”

A Method for the Prediction of Supersonic Compressor Blade Performance

“…Recent measurements, for example Strazisar(1985), and holographic pictures, Parker and Jones(1988), have demonstrated very clearly that away from the choked condition the blades do not operate with the leading edge shock attached. Instead the shock stands a little way forward of the leading edge and flow can spill from one pasage to the next.…”