Fluid Flow and Magnet Simulation in a Model Gearbox

Abstract

Essential components in a transmission system such as gears, bearings and shafts are prone to damage and degradation due to frictional contact between them. Fric tional contact between the mechanical components produces wear and eventually leads to breakdown of the gearbox. Lubricants are used to prevent excessive wear and early failure of the gearbox. Nevertheless, wear in a gearbox is unavoidable. If it is left unchecked, it produces more debris and increase the rate of wear leading to an increase in the maintenance cost of the lubricant. One possible methods to reduce the wear rate is to place a magnet in the gearbox as a measure to ensure cleanliness of the lubricant. The magnet is intended to capture and retain the wear debris. This thesis aims to combine fluid flow and magnetic simulation in a gearbox us ing commercial software (Star CCM+) and also provide information regarding the best placement of the magnet in the gearbox. As the flow velocity and the domain size is high, unrealistic remanent flux density is implemented so that the particles are attracted to the magnet by overcoming the hydrodynamic forces. Different particle sensitivity analysis have been conducted to understand the particle accumulation in the domain. The magnet is suggested to be positioned in the last right region of the gearbox as more particles are accumulated in this region irrespective of from where the particles are injected or any small change in size and shape of the par ticles. The flow inside the gearbox makes the particles move towards the magnet without much resistance. The magnet does not have to do much work to attract the particles. Hence positioning the magnet in this region reduces the rate of wear inside the gearbox.