Numerical and Experimental Study on the Cooling Performance Affected by Ventilation Holes of a BLDC Motor for Multi-Copters

A multi-copter or drone is a small, typically unmanned helicopter having more than two rotors. As the use of multi-copter has increased rapidly in recent years in a wide range of field such as military, agriculture, logistics, academic, surveillance and leisure, technical requirement for long-term use are inevitably followed. As a limitation on the long-term use of the multi-copter, excessive heat generation of the driving motor is regarded as one of the main causes. In order to solve this problem, it is essential to design an optimal heat dissipation structure. In this study, 3D computational fluid dynamics investigation and experimental verification have been performed to evaluate the effectiveness of ventilation holes on the cooling performance of the outer-rotor type BLDC motor used for a multi-copter. Then, adequate ventilation hole design is suggested through the comparative analysis of main heat transfer path and dominant internal flow path via Computational Fluid Dynamics.