Optimization of Drum Brake System in HCVs Using Two-Way Coupled CFD Approach

Abstract

<div class="section abstract"><div class="htmlview paragraph">The brake systems are given top priority by automotive OEMs in the development of medium and heavy commercial trucks and buses, which can carry increased loads. When trucks and buses are travelling at high speeds or crossing downhill, during braking operations, the friction faces (brake drum and liner) experience a significant rise in temperature due to the conversion of kinetic energy into heat energy within seconds. This lowers the friction coefficient at the interface, resulting in distortions, thermal cracks, hub grease burning, and overheating. Drum brake system designs must be improved and optimized to dissipate more heat from the brake drum assembly and prevent brake failure. Nowadays advance transient numerical simulations assist in the design, development and optimization of the brake system to visualize 3D flow physics and temperature variations throughout the brake duty cycles.</div><div class="htmlview paragraph">In the current study, different Cases of drum brakes to improve cooling efficiency are evaluated. Modifications are done by the addition of different fin shapes on drum brake and deflector on rear axle. These Cases are assessed for continuous braking cycles followed by extended cooling. Lattice Boltzmann-based solver EXA PowerFLOW is used to carry out simulations by demonstrating a fully integrated two-way coupling approach. This coupling helped in simulating larger duration of duty cycles for heavy commercial vehicles. In this coupling approach, flow simulations (PowerFLOW) are carried out to predict HTCs and other flow parameters for different vehicle speeds. These parameters are imported into a standard thermal solver (PowerTHERM), where different brake duty cycles are run by solving radiation and conduction in detail. All brake drum parts are meshed as solids and the actual rotation of the wheel and drum brake is considered to capture all modes of heat transfer in detail.</div><div class="htmlview paragraph">To evaluate the fins and deflector’s effect on cooling efficiency, numerous simulations are carried out. Different parameters like heat transfer coefficients (HTCs), flow rate via the ventilation slot, peak temperature attained during the duty cycles and cooling performance in an extended cooling cycle are used to compare these Cases. It has been found that brake drum with aerodynamically (curved angle) designed fins on drum surface shows relatively better results in terms of all the parameters mentioned above.</div></div>