Hot-wire anemometer invariant to temperature of the medium

The constant temperature hot-wire anemometer (CTHA) is at present one of the most widely used instruments for the study of turbulence, particularly of gaseous mediums [i, 2]. It is known that, in practice, the effect of the gas stream temperature 8g on the output signal u v of the anemometer (u is the output voltage of the measuring instrument, v is the gas stream velocity), i.e., uv = f(v, eg), is quite often one of the most negative factors which lower the accuracy characteristics of the instrument. As it follows from [2, 3], the relative error in determining the velocity 6vlv=const with a variation in eg is 1-2% for one degree and over. The error in determining v can be quite substantial when the ranges of variation in e~relative to thecalibration temperature egr of the anemometer are significant. In this manner, the problem of providing for the invariance of Uv, relative to the variations in eg, is an important one. The methods which, in our opinion, are most successful in solving this problem are briefly discussed below.