Abstract
The fluid flow in the runner of a hydraulic turbine has serious uncertainties. The sealing failure of the magnetorheological (MR) fluid sealing device of the main shaft of the hydroturbine, caused by a sudden change in speed, has always been a difficult topic to research. This study first derives the MR fluid seal pressure and unbalanced curl equations of the hydroturbine main shaft, and then analyzes the seal pressure and friction heat under different rotational speed mutation conditions through experiments. After verification, the temperature field and magnetic field distribution of the MR fluid sealing device of the main shaft of the hydraulic turbine are obtained via numerical calculation. The results show that the external magnetic field affects the magnetic moment of the magnetic particles in the MR fluid, resulting in a significant change in frictional heat, thereby reducing the saturation of magnetic induction intensity of the MR fluid. This results in a decrease in the sealing ability of the device. The size and abrupt amplitude of the main shaft of the hydraulic turbine, and friction heat is positively correlated reducing the sealing ability of the device and causing sealing failure. Based on our results, we recommend adding the necessary cooling to the device to reduce the frictional heat, thereby increasing the seal life of the device.
Highlights
With the rapid development of the world economy, energy demand has rapidly increased
Through experiments, the viscosity–temperature curve and magnetic temperature curve of the MR fluid at different temperatures and external magnetic field strengths are measured; a function is written into the software through the UDF custom function in ANSYS; an ANSYS co-simulation of the MR fluid is performed with the Maxwell and Fluent software
By observthe same rotational speed, the maximum temperature of the MR fluid sealing device is ing the same rotational speed, the maximum temperature of the MR fluid sealing device noted in the sealing gap, which is approximately 55 ◦ C; it diffuses to the outside to is noted in the sealing gap, which is approximately 55 °C; it diffuses to the outside to realize heat exchange with the outside world
Summary
With the rapid development of the world economy, energy demand has rapidly increased. The main shafts of hydraulic turbines mostly use rubber, packing, floating-ring, and labyrinth seals [2] These sealing methods have several problems, including having complex structures and low reliability and being worn down. In 2017, Susan–Resiga [16] experimentally studied the apparent viscosity and magnetization of different magnetic induction intensities, shear rates, magnetic solid particle sizes, and volume fractions to obtain an infinite measure of the sealing performance of MR fluids. This study first derives the MR fluid seal pressure and unbalanced curl equations of the turbine main shaft, obtains the pressure values and frictional heat under different speed mutation conditions through experiments. The magnetic field and temperature field distribution of the MR fluid sealing device are obtained using numerical calculation, which provides a new theoretical reference for the research on MR fluid sealing
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