First measurements with a laser Doppler anemometer in a high pressure natural gas pipe

The applicability of Laser Doppler Anemometry (LDA) to velocity measurement in a natural gas pipe and the inaccuracy of the Doppler frequencies are studied. Test measurements show that the measuring procedure and the calibration methods can be applied at high pressure. The frequency inaccuracy is measured using a remote control programmable interference generator to obtain the signal-to-interference ratio required. The LDA emitting and receiving optics is studied, based on light particle forward scattering and backscattering for signal-to-interference ratio measurement. Bad signal quality due to high fluid velocity can be compensated for with higher laser performance. The frequency of the laser Doppler signals can be measured with an accuracy of 0.0001.