The Experimental Investigation Of DME Engine Piston's Temperature Field And Its 3-D Finite Element Analysis

DME (Dimethyl Ether) is a type of clean and oxygen-containing fuel which is considered as the main alternative fuels for internal combustion engines due to the broad resources of its feed stocks. As a key part of the DME engine, the piston's structural reliability directly influences the security and operating performance of the whole engine, especially under high speed and series abrasion working conditions. In this paper, in order to provide a scientific basis for the improvement of piston structure and the optimization of DME engine performance, the temperature field and thermal stress of piston of DME engine were thoroughly studied by the way of both experimental measurement and numerical simulation.Based on a widely reading and detailed study of relevant articles, this paper decided to use the hardness plug thermometry for the measurement of piston temperature field through comparing many methods. The key technology of the hardness plug thermometry were thoroughly analyzed and proved, such as the principle of the thermometry, the arrangement of measuring point, the formulation of the standard HV-T curve and the technical requirement of installation. Then, a DME engine test bench was set up and a certain working condition for piston temperature field experiment of DME engine was confirmed after comparing the operating performance under different working conditions.The hardness plug thermometry was used to measure the piston temperature field of DME engine and diesel engine under the same working conditions. The temperature distribution of pistons on different engines were contrasted and analyzed. The result showed that the thermal load of DME engine was lower than that of the diesel engine under the same working conditions.The simulation of heat release rates and the temperature history inside the cylinder were also carried out by the Waston zero-dimensional combustion model based on the experimental indicator diagram of work. The calculation results essentially explained the reason that the thermal load of DME engine was lower than that of the diesel engine under the same working conditions. Piston's 3-dimensional model was built by Pro/E software, and then 36954 nodes and 198594 elements were generated after been meshed by Hyper-mesh software. The 3-dimensional finite element analysis of DME engine's piston was carried out though the thermal analysis module and couple-field analysis module of the ANSYS software. The calculation results of piston's temperature field matched the testing result very well.Finally, the piston's von mises stress and von mises total strain under the couple load of thermal and mechanic load was calculated. The calculation result showed that the von mises stress and von mises total strain of DME engine's piston were in the permission range of its design requirement under the declared working condition.