To study the distribution and dissipation of braking power of wet multidisc brake and determine thermal load and thermal flux distribution between mated discs, the concept of distributing brake power four times was pu...To study the distribution and dissipation of braking power of wet multidisc brake and determine thermal load and thermal flux distribution between mated discs, the concept of distributing brake power four times was put forward. The third and the fourth distribution of brake power were calculated by using finite element(FE) software ANSYS. The third and the fourth distribution of wet multidisc brake are mainly related to material characteristics of discs during emergency braking, while most of the braking power is carried off during continuous braking. Basis is provided for further analysis of disc failure and applicability of different friction materials.展开更多
The hydraulic caliper disc brake system with air-over-oil is widely adopted at present for heavy vehicles,which makes use of air pressure system propelling the hydraulic pressure system acting on friction plates divid...The hydraulic caliper disc brake system with air-over-oil is widely adopted at present for heavy vehicles,which makes use of air pressure system propelling the hydraulic pressure system acting on friction plates divided and combined for braking.There are some disadvantages such as pneumatic components failure,dust polluted and produce lots of heat in hydraulic caliper disc brake system.Moreover,considering the demands of the high speed,heavy weight,heavy load and fast brake of heavy vehicles,the full power hydraulic brake system based on double pipelines for heavy vehicles is designed and analyzed in this paper.The scheme of the full power hydraulic brake system,in which the triloculare cylinder is controlled by dual brake valve,is adopted in the brake system.The full power hydraulic brake system can accomplish steering brake,parking brake and emergent brake for heavy vehicles.Furthermore,electronic control system that is responsible for coordinating the work of hydraulic decelerator and hydraulic brake system is developed for different speed brakes.Based on the analysis of the influence of composed unit and connecting pipeline on braking performance,the nonlinear mathematic model is established for the full power hydraulic brake system.The braking completion time and braking pressure in braking performance of the double-pipeline steering brake and parking brake are discussed by means of simulation experiments based on Matlab/Simulink,and the simulation results prove that the braking performance of steering brake and parking brake meets the designing requirement of the full power hydraulic brake system.Moreover,the test-bed experiments of the brake system for heavy vehicles are carried out.The experimental data prove that the braking performance achieves the goal of the design,and that the full power hydraulic brake system based on double pipelines can effectively enhance braking performance,ensure braking reliability and security for heavy vehicles.展开更多
The wind-assisted propulsion system is becoming one of the most popular and efficient ways to reduce both fuel consumption and carbon dioxide emission from the ships.In this study,several analyses have been carried ou...The wind-assisted propulsion system is becoming one of the most popular and efficient ways to reduce both fuel consumption and carbon dioxide emission from the ships.In this study,several analyses have been carried out on a model of bulk carrier fitted with five rigid sails with a 180°rotating mechanism for maximum usage of wind power and a telescopic reefing mechanism for folding it during berthing.The stability of the ship has been verified through the calculations of initial stability,static stability,and dynamic stability through the fulfillment of the weather criterion using MAXSURF software.The structural analysis of the sail was carried out in ANSYS static structural module.Several flow simulations were carried out in ANSYS fluent module to predict the thrusts produced by the sails at different apparent wind angles,which would in turn reduce the thrust required from the propeller.In this way,the brake horse powers required for different sail arrangements were analyzed to find out a guideline for this wind propulsion system to generate better powering performances.To consider drift and yaw effect on propulsion system,an MMG mathematical model–based simulation was carried out for different drift angles of motion of the ship considering hard sail–based wind loads.Through these analyses,it has been found out that the hard sail–based wind-assisted propulsion system in some cases have produced a reduction of more than 30%brake power in straight ahead motion and around 20%reduction in case of drifting ships compared to the model having no sails.展开更多
为提升电力机车制动产生的大量再生制动能量的回收利用率,同时兼顾补偿单相牵引供电系统在电网中引起的电压不平衡问题,本文提出了一种基于YNd变压器-多端口变换器的铁路混合储能系统(YNd-multiport converter based railway hybrid ene...为提升电力机车制动产生的大量再生制动能量的回收利用率,同时兼顾补偿单相牵引供电系统在电网中引起的电压不平衡问题,本文提出了一种基于YNd变压器-多端口变换器的铁路混合储能系统(YNd-multiport converter based railway hybrid energy storage system,YNd-MC-RHESS)。首先,分析了YNd-MC-RHESS的工作原理及其工作模式。其次,以提高再生制动能量的利用率为主要目标,基于非线性电流控制,提出了多端口变换器的功率优化调控策略,在交流/直流(AC/DC)变换器中引入非线性控制,提升了多端口变换器的响应速度与混合储能的能量分配效率。最后,基于典型工况,通过半实物动态模拟验证了所提控制策略可以调度功率在不同端口间按需转移,同时不同介质储能功率可合理分配与存储释放。实验结果表明,混合储能装置投入后,再生制动能量的利用率为93.67%,实现了再生制动能量的高效利用。展开更多
文摘To study the distribution and dissipation of braking power of wet multidisc brake and determine thermal load and thermal flux distribution between mated discs, the concept of distributing brake power four times was put forward. The third and the fourth distribution of brake power were calculated by using finite element(FE) software ANSYS. The third and the fourth distribution of wet multidisc brake are mainly related to material characteristics of discs during emergency braking, while most of the braking power is carried off during continuous braking. Basis is provided for further analysis of disc failure and applicability of different friction materials.
基金supported by Basic Scientific Research Operation Cost of Central Universities of China (Grant No. 200903168)
文摘The hydraulic caliper disc brake system with air-over-oil is widely adopted at present for heavy vehicles,which makes use of air pressure system propelling the hydraulic pressure system acting on friction plates divided and combined for braking.There are some disadvantages such as pneumatic components failure,dust polluted and produce lots of heat in hydraulic caliper disc brake system.Moreover,considering the demands of the high speed,heavy weight,heavy load and fast brake of heavy vehicles,the full power hydraulic brake system based on double pipelines for heavy vehicles is designed and analyzed in this paper.The scheme of the full power hydraulic brake system,in which the triloculare cylinder is controlled by dual brake valve,is adopted in the brake system.The full power hydraulic brake system can accomplish steering brake,parking brake and emergent brake for heavy vehicles.Furthermore,electronic control system that is responsible for coordinating the work of hydraulic decelerator and hydraulic brake system is developed for different speed brakes.Based on the analysis of the influence of composed unit and connecting pipeline on braking performance,the nonlinear mathematic model is established for the full power hydraulic brake system.The braking completion time and braking pressure in braking performance of the double-pipeline steering brake and parking brake are discussed by means of simulation experiments based on Matlab/Simulink,and the simulation results prove that the braking performance of steering brake and parking brake meets the designing requirement of the full power hydraulic brake system.Moreover,the test-bed experiments of the brake system for heavy vehicles are carried out.The experimental data prove that the braking performance achieves the goal of the design,and that the full power hydraulic brake system based on double pipelines can effectively enhance braking performance,ensure braking reliability and security for heavy vehicles.
文摘The wind-assisted propulsion system is becoming one of the most popular and efficient ways to reduce both fuel consumption and carbon dioxide emission from the ships.In this study,several analyses have been carried out on a model of bulk carrier fitted with five rigid sails with a 180°rotating mechanism for maximum usage of wind power and a telescopic reefing mechanism for folding it during berthing.The stability of the ship has been verified through the calculations of initial stability,static stability,and dynamic stability through the fulfillment of the weather criterion using MAXSURF software.The structural analysis of the sail was carried out in ANSYS static structural module.Several flow simulations were carried out in ANSYS fluent module to predict the thrusts produced by the sails at different apparent wind angles,which would in turn reduce the thrust required from the propeller.In this way,the brake horse powers required for different sail arrangements were analyzed to find out a guideline for this wind propulsion system to generate better powering performances.To consider drift and yaw effect on propulsion system,an MMG mathematical model–based simulation was carried out for different drift angles of motion of the ship considering hard sail–based wind loads.Through these analyses,it has been found out that the hard sail–based wind-assisted propulsion system in some cases have produced a reduction of more than 30%brake power in straight ahead motion and around 20%reduction in case of drifting ships compared to the model having no sails.
文摘为提升电力机车制动产生的大量再生制动能量的回收利用率,同时兼顾补偿单相牵引供电系统在电网中引起的电压不平衡问题,本文提出了一种基于YNd变压器-多端口变换器的铁路混合储能系统(YNd-multiport converter based railway hybrid energy storage system,YNd-MC-RHESS)。首先,分析了YNd-MC-RHESS的工作原理及其工作模式。其次,以提高再生制动能量的利用率为主要目标,基于非线性电流控制,提出了多端口变换器的功率优化调控策略,在交流/直流(AC/DC)变换器中引入非线性控制,提升了多端口变换器的响应速度与混合储能的能量分配效率。最后,基于典型工况,通过半实物动态模拟验证了所提控制策略可以调度功率在不同端口间按需转移,同时不同介质储能功率可合理分配与存储释放。实验结果表明,混合储能装置投入后,再生制动能量的利用率为93.67%,实现了再生制动能量的高效利用。
