An efficient method utilizing the concept of inverse heat conduction is presented for the thermal analysis of pistons based on application to a liquid-petroleum-liquid injection (LPLI) engine piston. An inverse heat conduction problem is established in the form of an optimization problem. In the optimization problem, the convection heat transfer coefficient (HTC) on the combustion-side surface of the piston is defined as the design variable, while the error between the measured and analysed temperatures is defined as the objective function. For the optimization, two consecutive steps consisting of an axisymmetric and a three-dimensional problem are presented in order to reduce computation time and to obtain stable convergence. The optimum distribution of the HTC at the top surface of the piston is successfully determined through a numerical implementation. The temperature obtained via an analysis using the optimum HTC is compared with the measured temperature, and reasonable agreement is obtained. The present method can be effectively utilized to analyse the temperature distribution of engine pistons.
The responses of a cabinet for a reactor protection system under seismic loadings are analysed by using the finite-element method, and its dynamic characteristics are evaluated. Analysed modes are compared with the measured data from a resonance search test. The structural safety of the cabinet is evaluated considering the required response spectrums of the operation-base and safe-shutdown earthquakes. The transient response of the cabinet is analysed by utilizing the measured acceleration of the vibration table representing the seismic motion of the ground. Time histories of accelerations at the locations of major internal parts are extracted. The transient responses are compared with those from the seismic test and the results were found to closely represent the system.
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