Temperature error in a hydrostatic leveling system and its reduction

Abstract

Hydrostatic leveling systems (HLS) are used for long-term measurements of vertical displacements and inclination of various objects. The temperature gradient caused by inhomogeneous and time-variable environmental conditions can lead to a significant error. Experimental studies carried out in this paper demonstrated that the accuracy of the system can be improved through forced circulation of the fluid. Measurements should be performed in the restricted time interval after completion of the mixing, because the temperature of the sections of the hose gradually reverts to the original state. A detailed analysis of the temperature processes in the simplified analog of a long-base HLS during mixing is carried out based on the results of numerical simulation. A model of the process of liquid mixing in the hydrostatic level is considered and verified. Heat transfer in the flowing liquid is described by the one-dimensional equation, and the problem of heat conduction in a hose is solved in the axisymmetric formulation. The solution of the coupled heat transfer problem was carried out by the finite element method. The influence of the geometrical parameters of a long-base hydrostatic level and pump flow rate on the mixing time and temperature heterogeneity of the liquid were investigated. The mixing procedure and sequence of actions discussed in this work can significantly reduce the error of the measuring system and provide an adequate selection of its parameters.