Design Of A Water-cooled Disc Brake And Research On Its Heat Dissipation Performance

The screw drilling tool test bench is a test system used to test the actual working characteristics of screw drilling tools,and it is responsible for the important task of evaluating the screw drill operational reliability.With the gradual increase in the output torque and power requirements of the screw drilling tool,the requirements for its performance detection system are also increasing.The rotary torque loading device is an important part of the screw drilling tool performance testing system,and its output characteristics and working stability directly determine the feasibility and accuracy of the screw drilling tool performance testing.At present,the commonly used torque loading devices often lead to inaccurate torque loading or even device damage due to high temperature rise of components during drilling tool testing,which makes it difficult to ensure the accuracy of drilling tool performance testing.This paper designs a water-cooled disc brake as a rotary loading device to provide load torque for the screw drilling tool by analyzing the working characteristics of the screw drilling tool and the torque loading requirement for its performance detection.The heat dissipation performance of the brake is analyzed by CFD numerical simulation,and the heat dissipation characteristics are improved and optimized based on the measures of heat transfer enhancement.The main contents of this article are as follows:(1)According to the working characteristics of the screw drilling tool and its performance testing requirements,the structure scheme of the water-cooled disc brake is designed and analyzed;the size of the brake components is calculated with 20 k N·m as the target torque.and the three-dimensional model of the overall structure of the water-cooled disc brake is modeled by Solidworks;finally,the input and output characteristics of the brake are analyzed,and the results show that the designed water-cooled disc brake has good control characteristics.(2)Based on the heat transfer principle of water-cooled disc brakes,its physical model is simplified,and the fluid-structure coupling heat transfer model of the brake is established based on the CFD method.The thermal load of the brake disc,the heat flow distribution coefficient and the coolant inlet flow were calculated theoretically,the boundary parameters of the simulation analysis are obtained.The fluid-structure coupling heat dissipation process is simulated by Fluent software,and the coolant flow characteristics and the heat dissipation characteristics of the brake disc are analyzed.The simulation results show that under the original heat dissipation structure,the coolant flow distribution in the cooling channel is very uneven,the brake disc surface temperature is high and there is a large gradient,the watercooling effect is not good.(3)Based on the simulation results of the original heat dissipation structure,combined with the principle of enhanced heat transfer,it is proposed to improve the heat dissipation structure of the brake by adding the baffle structure,the pin fin structure and the adjustment of the transition structure of the inlet and outlet pipes.The simulation results show that under the improved heat dissipation structure,the coolant flow state is significantly improved,the temperature of the brake disc is effectively controlled,and the heat dissipation performance of the brake is significantly improved.Subsequently,the comprehensive evaluation factor of enhanced heat transfer(PEC)was used as the comprehensive heat dissipation performance evaluation index of the brake.Based on the improved heat dissipation structure,the influence of the shape of the pin fin on the comprehensive heat dissipation performance of the brake was deeply investigated.The results showed that under the equilateral triangle pin fin heat dissipation structure,the comprehensive heat dissipation performance of the brake is relatively good,which is 3.4%,2.4% and 4.4% higher than the circular,the elliptical and water droplet flow pin fin structures respectively.(4)Based on the equilateral triangle pin fin heat dissipation structure,the relevant parameters of the pin fin structure were optimized through single factor experiment and orthogonal experiment.Based on the optimized heat dissipation structure,the influence of the coolant flow rate and the cooling medium on the heat dissipation performance of the brake is analyzed.The results show that based on the heat dissipation structure of the equilateral triangle pin fin,the radial arrangement gap ratio of the pin fin has no significant effect on the PEC;the order of effect of other structural parameters on the PEC is the distance between the top of the pin fin and the brake disc,the side length of the pin fin,the radial distribution number of the pin fin,the depth of the water tank,and the circumferential distribution number of the pin fin;and the optimal structural parameters combination is: the depth of the sink is 13 mm,the side length of the equilateral triangle is 10 mm,the distance between the brake disc and the pin fin top is 1mm,the number of pin fins in the circumferential cross distribution in the tank is 66,and the number of radial equidistant distribution is 4;the PEC under the optimized heat dissipation structure is increased by 21.4% compared to before optimization,and 27.6% higher than the original structure.Based on the optimized pin fin heat dissipation structure,when the coolant inlet flow rate is 0.6L/s,the brake's comprehensive heat dissipation performance is better.And at room temperature,compared to 50% glycol solution,pure water as the cooling medium can provide better heat dissipation performance for the brake.