Newly developed method for measuring jacket pressure coefficient of controlled-clearance piston-cylinders

摘要

Pressure dependence of the effective area Ae of controlled-clearance piston-cylinder (CCPC) has been evaluated based on the Heydemann-Welch model. Among deformational characteristics to be evaluated, the jacket pressure coefficient d, which denotes the relative change in Ae due to applied jacket pressure pj, is focused in this paper. A new method is proposed for precisely estimating d at pressures up to 1 GPa. The method uses precise pressure transducers as monitoring devices. Both pj and weights loaded on CCPC are changed so that the pressure generated by CCPC remains constant, which is monitored by the transducers. The change in Ae due to pj is estimated by the change of the weights loaded on the CCPC. Using this method, d for a 1 MPa/kg CCPC is measured at pressures up to 1 GPa. The new method is advantageous over the conventional method in terms of efficiency and operability especially at higher pressures.