CFD-based design and analysis of air-bearing-supported paint spray spindle

Abstract

Copyright © 2018 The Author(s). In this paper, an analytical scientific approach is presented for the design and analysis of an air-turbine-driven paint spray spindle, and it is used to improve further the design concept of the existing spindle applied in auto-motive coating and paint spraying applications. The current spindle on the market can operate at a maximum speed of 100,000 rpm and features a maximum bell size of 70 mm diameter. Given the increasing demands forhigh automotive coating/painting quality and productivity in assembly, the design and development of a paint spray spindle with a speed of 145,000 rpm or higher is needed. Computational fluid dynamics (CFD)-based simulation is applied in the approach. Accordingly, CFD simulation-based design and analysis are undertaken, covering the characteristic factors of velocity, pressure of the air supply, rotational speed of the air-turbine, and torque and force reaction on the turbine blades. Furthermore, the turbine blade geometric shape is investigated throughthe simulations. Three geometrical concepts have been investigated against the original model. The results onConcept_03 verified the higher angular velocity speeds against the theoretical model. The pressure and velocity effects in the blades have been investigated. The results show that the pressure and velocity of the air supply driving the turbine are critical factors influencing the stability of turbine spinning. The results also demonstrate that the force acting on the blades is at the highest level when the adjacent face changes from a straight surface into a curve. Finally, changing the geometrical shape in the turbine likely increases the tangential air pressure at the blades surface and relatively increases the magnitude of the later altorque and force in the spindle. Notwithstanding this condition, the analytical values surpass the theoretical target values.