Characteristic Analysis of Water Lubricated Plain Journal Bearing under Transient Load

Transient load has a huge impact on the life and stability of water-lubricated bearings. In this paper work, CFD software is used to analyse the dynamic characteristic of water lubricated bearings under different transient loads of 500N, 1000N, 2000N and 3000N. The water film pressure contour distribution at different transient time was given. The time-varying relationships between the different transient loads with bearing forces, the journal displacement, the maximum value of water film pressure as well as the minimum value of water film thickness are obtained. The results show that with the increase of transient load, the effective bearing area of dynamic water pressure film decreases, and the maximum pressure increases. The bearing forces, the journal displacement, the maximum value of water film pressure as well as the minimum value of water film thickness will increase fast.

Solar Convertor Performance Analysis Fitting Load at Two Different Local Areas

Multilevel converters are divided into diode clamp inverters, flying capacitor inverters and cascade inverters. The main objective of this work is to design a solar energy system to move loads away from production points and study the system to improve its reliability and efficiency. And analyze the system with the inverter field-oriented feedback control under transient load conditions to analyze the efficiency of the system in driving motor loads. The simulated work in this work demonstrates the possibility of using a photovoltaic cell to power a motor via a three-phase bridge inverter. It can be concluded that this work will contribute to the analysis of solar modules for the operation of a motor using a PWM inverter. The work also aims to perform an analysis of the solar energy system that moves loads away from the point of generation. The drive commands at the load points are analyzed during the process, taking into account the transient load conditions.

On Short-Term Fatigue Analysis for Wind Turbine Tower of Two Semi-Submersible Wind Turbines Including Effect of Startup and Shutdown Processes

Fatigue limit state design check for offshore wind turbines is based on SN curves and the Palmgren–Miner rule approach and focuses normally on stationary processes for which startup and/or shutdown operations induced transient load processes are normally not accounted for. However, large databases of real-time measurements show that the shutdown and startup operations may appear in any operational conditions and the frequency of such operations could be considerable. Although design standards require fatigue design checks for the transient load processes induced by startup and shutdown operations, relevant publications addressing this issue are very limited in particular for floating wind turbines. This paper focuses on analyzing the importance of startup and shutdown induced transient load processes on fatigue damage in the tower of two MW-level horizontal axis semi-submersible wind turbines. The analysis is carried on by comparing short-term fatigue damage in several environmental conditions with and without the startup and shutdown induced transient load processes. It is found that, in many environmental conditions, startup and/or shutdown operations may make an increase in short-term fatigue damage by 10% to 100%, while in some situations, the fatigue damage may be increased by up to 200%. The importance of the transient load processes on long-term fatigue damage is related to the occurrence frequency of startup and shutdown events. Publicly available data indicate that the average time between two consecutive shutdown events might be less than 39 h. However, more data and analysis are needed regarding these issues.