平行レーザビームを用いた熱線の傾斜角測定法

抄録

A new method was developed for determining a slant hot-wire inclination to the axial flow direction in order to accurately measure the transverse velocity component. The method requires dual parallel laser beams near the focal point such as Laser-Two-Focus velocimeter beams, one of which can rotate around the other. Since the squared hot-wire bridge output is proportional to the mean value of the beam intensity exposed on the hot-wire element, the bridge output indicates the maximum variation, when the slant wire is exposed by just dual beams. This rotating angle is referred to as the slant angle of the wire, if necessary, relative to the freestream angle, which is exactly given by the Laser-Two-Focus velocimeter. Furthermore, it is pointed out in the measurement that the beams rotate in precession due to optical misalignment. This method may be applicable to optical alignment.