轮式装载机散热系统仿真和控制方法研究

发布时间：2018-03-16 10:25

本文选题：散热系统　切入点：CFD　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：作为装载机的重要组成部分,散热系统在维持装载机正常运行中扮演着必不可少的角色。装载机的发动机系统、传动系统、液压系统需工作在合适的温度范围内,过高温度会降低系统的可靠性、产生泄露等问题,影响装载机正常工作;温度过低会降低燃油利用率、污染物排放加重、系统功耗增加。作为工程机械装载机对发动机功率需求较大,发动机输出功率应主要应用于装载机工作系统,减少其他系统功率消耗,并达到节能减排的目的,因此对散热系统的研究可以使散热系统工作在最佳温度范围内,并降低散热系统功耗。这对于装载机高效、可靠的作业具有重要意义。本文依托校企合作项目,采用理论研究和数值仿真研究的方法,对装载机散热系统进行研究,通过一维与三维联合仿真的方法对装载机散热系统的换热特性进行研究,并依据仿真得到数据,建立基于散热系统功耗最小原则装载机散热系统控制策略,实现装载机独立散热。本文主要研究内容如下:(1)基于热力学第一定律和传热学理论对某款装载机的散热系统的产热量进行了计算;根据得到的散热量对风扇、水泵以及散热器进行了选型匹配。(2)利用CFD仿真软件Fluent对装载机散热系统进行分仿真分析,获得其动力舱内部的流场特性和温度场特性,并获得散热器风量与风扇转速关系,以此作为一维仿真的边界条件,并对装载机动力舱结构对散热系统的影响进行研究。(3)利用一维仿真软件AMESim建立装载机散热系统的一维仿真模型,并以三维仿真获得的风扇风量作为一维仿真边界条件实现联合仿真,通过一维仿真获得装载机散热系统内部温度特性。并基于一维仿真获得装载机散热系统散热量、气液温差、风量和冷却液流量关系,以此作为散热系统控制边界条件。(4)建立了基于散热系统功耗最小的装载机散热系统控制策略,通过仿真计算分别获得了风扇、水泵转速与散热系统功耗、环境温度的关系式。以功耗最小原则建立了风扇/水泵转速-散热功率-环境温度的MAP图表,通过PID反馈控制,搭建了完整的独立散热系统控制模型。通过AMESim-Simulink联合仿真分别针对不同散热工况、环境温度进行仿真验证,仿真结果显示控制系统可将系统温度维持在最佳范围,论证了独立散热系统控制策略的可行性。
[Abstract]:As an important part of the loader, the heat dissipation system plays an essential role in maintaining the normal operation of the loader. The engine system, transmission system and hydraulic system of the loader need to work in a suitable temperature range. If the temperature is too high, it will reduce the reliability of the system and cause problems such as leakage, which will affect the normal operation of the loader. If the temperature is too low, the fuel utilization ratio will be reduced, and the pollutant emissions will be increased. The power consumption of the system is increased. As the loader of construction machinery has a great demand for engine power, the engine output power should be mainly used in the loader working system to reduce the power consumption of other systems and to achieve the purpose of energy saving and emission reduction. Therefore, the research on the heat dissipation system can make the heat dissipation system work in the optimum temperature range and reduce the power consumption of the heat dissipation system, which is of great significance for the efficient and reliable operation of the loader. The heat dissipation system of loader is studied by theoretical research and numerical simulation. The heat transfer characteristics of heat dissipation system of loader are studied by the method of one dimension and three dimensional simulation, and the data are obtained according to the simulation. Based on the principle of minimum power consumption of heat dissipation system, the control strategy of heat dissipation system of loader is established. The main contents of this paper are as follows: (1) based on the first law of thermodynamics and the theory of heat transfer, the heat production of the heat dissipation system of a certain loader is calculated. The water pump and radiator are selected and matched. The heat dissipation system of loader is simulated and analyzed by CFD simulation software Fluent. The characteristics of flow field and temperature field in the power cabin are obtained, and the relationship between the air volume of the radiator and the speed of the fan is obtained. Taking this as the boundary condition of one-dimensional simulation, and studying the influence of the power cabin structure of loader on the heat dissipation system, the one-dimensional simulation model of the heat dissipation system of loader is established by using one-dimensional simulation software AMESim. The fan air volume obtained by 3D simulation is used as the boundary condition of one-dimensional simulation to realize the joint simulation. Through one-dimensional simulation, the internal temperature characteristics of the heat dissipation system of the loader are obtained. Based on the one-dimensional simulation, the heat dissipation of the heat dissipation system of the loader and the temperature difference between gas and liquid are obtained. Based on the relationship between air volume and coolant flow rate, as the control boundary condition of heat dissipation system, the control strategy of loader heat dissipation system based on the minimum power consumption of heat dissipation system is established, and the fan is obtained by simulation. Based on the principle of minimum power consumption, the MAP diagram of fan / pump rotational speed, heat dissipation power and ambient temperature is established, which is controlled by PID feedback. A complete control model of independent heat dissipation system is built. The simulation results show that the control system can maintain the system temperature in the optimal range by AMESim-Simulink simulation. The feasibility of the control strategy of independent heat dissipation system is demonstrated.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH243

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