Experimental study of water hydraulics application in aviation

摘要

Purpose - The purpose of this paper is to report an experimental study on the effects of various parameters, such as varying flow velocities of water in the pipe, insulating the water pipe, and heating the pipe, to prevent pressurized water in a water hydraulic system from freezing under sub-zero ambient temperature environment. Design/methodology/approach - An experimental test rig was designed, fabricated, and set up to conduct several experiments to investigate the time taken for water to freeze under sub-zero ambient temperature at -20° C and with the water initially at a higher temperature than the ambient. Findings - The experiments show that it would take about 90 min for water in the pipe to freeze completely when there is no flow, or water is flowing at slow speed, in the pipe. The results also show that the use of insulation on the pipe would delay the freezing of water inside the pipe; and if used together with heating at several locations on the pipe, freezing of water inside the pipe could be prevented completely. Originality/value - This paper usefully shows that insulation and heating in a water hydraulic system can prevent freezing of water in the pipe. The promising results of the experimental work mean that water might be able to replace oil in hydraulic systems on aircraft and other low-temperature applications.