Magnetorheological (MR) transmission that uses the rheological effect of MR fluid to transfer power is a new form of power transfer, which can achieve stepless control of torque and speed by adjusting the intensity of external magnetic field. In the study, a water-cooling heat dissipation scheme was proposed. The temperature simulation of MR transmission under natural heat dissipation and water-cooling heat dissipation was carried out by using the finite element method. Based on the design of the water-cooling MR transmission device (MRTD), the torque transmission and temperature rise characteristics of the MRTD were studied, and the influence of the heat dissipation mode on the transmission torque of the device was explored. Results show that the water-cooling method can control the temperature rise of the MRTD effectively.

In order to solve cylinder-scraping of a four-cylinder high speed diesel engine, based on the measurement of piston temperature, the piston temperature field was numerically simulated by using temperature fitting method, the calculation results were well consistent with the measured temperature. By finite element analysis of piston thermal load based on the calculation results as temperature load, enlarging oil cooling cavity in the piston head was proposed to enhance cooling locally, which could effectively reduce temperature of the piston head and the first ring groove and avoid the occurrence of cylinder-scraping.

The component and mission of CODOG propulsion system were analyzed in this paper. According to the mission variation, different operation conditions were introduced and mission reliability models of each condition were established by the use of reliability theory. After reliability data of main component of CODOG propulsion system been obtained, mission reliability of each condition was calculated and its phased mission was simulated through MATLAB software. Relative curve between system reliability and working time was found. The results show that, mission reliability of cruise condition is the biggest while phased mission reliability is the smallest. System availability is bigger than reliability after taking maintainability into account. System reliability can increase to a great extent and its useful life is longer by improving maintainability of its component.

Aiming to solve the problem of magnetorheological transmission heat dissipation, this study designs the magnetic circuit of a water-cooling magnetorheological transmission device based on fundamental electromagnetics theory. Finite element method is used to simulate the magnetic field of the measurement device. Results show that the working magnetic induction can reach 0.56 T when the current is 2.0 A, which can satisfy design requirements. The intensity of magnetic induction in the work space increases with the increase of excitation current and permeability of magnetically conductive material, whereas intensity decreases with the increase of work space size. The thickness and cross-sectional dimension of the guidepost group at the heat-dissipating unit have no significant effect on the intensity distribution of magnetic induction of the entire device.