Measurements of spinning rotor gauge response to step change of suspension head temperature

Abstract

The response of a spinning rotor gauge (SRG) to step change of the surrounding temperature has been studied. The suspension head with the ball and measuring thimble has been placed in a thermostat. The temperature of the thermostat was kept constant at selected temperatures for several hours, changed thereafter by a few K, and kept constant at the new temperature again. Measurements were performed in a range of ±4 K around nominal room temperature of 296 K. After a sudden change of the thermostat temperature, the temperature-induced instability of the gauge zero reading (residual drag (RD)) has been measured. From this, the temporal dependence of the ball temperature has been calculated by numerical integration, and the coefficient of linear thermal expansion of the ball material has been determined also. Measurements were repeated several times and the results were analysed statistically. The same ball has been measured in a stainless steel and a glass thimble. The results show that the thimble material has negligible effect on the time constant of the approach of the ball temperature to the equilibrium value. Our measurements showed also a small, but clearly evident temperature dependence of the SRG RD.