Measurements of the velocity and temperature in a turbulent flow by the laser photothermal effect with the new compulsorily phase locked interferometer

This article describes measurements of the velocity and temperature in a turbulent flow by means of a photothermal effect. We developed a new differential interferometer for detecting small phase variation caused by the photothermal effect without influence of turbulent phase fluctuation. The detected fringe point of the interferometer is scanned repeatedly by moving a photomultiplier. An electric system is constructed for compulsorily operating the interferometer at the maximum inclination point of the fringe intensity curve. Using a turbulent jet of nitrogen gas mixed with ethylene gas, we confirmed that this measurement system is useful to measure the velocity and temperature in the turbulent flow.