A Study on Measurements of Head Loss in Tunnels (On Control of Temperature in Measuring Device)

摘要

The purpose of the research is to develop the measuringdevice of the head loss in tunnels. This devicemeasures the differences of pressures between two points,using two independent devices of the same construction, inorder to obtain the head loss of tunnels. This device iscomposed of a container in which the air pressure is keptconstant as the reference pressure, and is equipped with amanometer to detect the difference between the referencepressure and the ambient air pressure.In order to obtain the exact constant pressure, it isnecessary for the container of the device to be kept at aconstant temperature with the accuracy of 10 -3℃. Firstly,both the structure and its operation of the devicewith double-walled container is explained. Secondly, thedynamics of temperature may be represented as an on-offcontrol system and its characteristics of temperature isanalyzed in detail. Finally, the experimental studies areperformed and the good regulation may be obtained at thehigh accuracy within 10-3℃.