Non-Intrusive Temperature Measurements in a Transonic Axial Compressor Using Spontaneous Rotational Raman Spectroscopy

Spontaneous rotational Raman spectroscopy was used to measure static temperature in a transonic axial compressor. This laser technique has the general advantages of such techniques, i.e. possibility of performing in-situ measurements with high spatial resolution and temporal resolution, and non-intrusiveness. The experimental investigations were performed just downstream the rotor for the design mass flow rate. The results are obtained from Raman scattering of air by using a high repetition rate pulsed Nd:YAG laser and a spectrally and spatially resolving detector system that consists of a triple spectrograph and a CCD camera. Raman Spectra presented here are integrated over 20 s. Profiles of temperature at various locations relative to the casing are presented and the measured temperatures are compared with theoretical values. Of great importance for the results is the accuracy of the technique, and a sensitivity analysis is performed to test the temperature on uncertainties in experimental parameters. It was shown that the absolute accuracy of temperature could be as low as ± 1 K in the 300 - 400 K operating range of interest.