冷却系统节温器部件的流阻分析及结构改进

某摩托车冷却系统阻力偏大，造成冷却系统漏水现象，经排查初步原因为散热器及节温器管路的总体阻力较大。为研究冷却系统节温器部件的流阻大小，采用CFD分析软件STAR-CCM+对节温器部件流场进行了数值模拟。结果表明节温器全闭状态下小循环流阻为187 kPa，对冷却系统总阻力影响较大。为降低节温器全闭状态下小循环流阻，研究了大节温器、双节温器、小循环连接管路内径对该阻力的影响。结果表明大节温器、双节温器结构可有效降低节温器全闭状态下小循环流阻，但在节温器全开时流经小循环的冷却液流量占比增加较大且成本高。在原节温器状态下，小循环连接管路内径增大，小循环流阻明显降低，而流经小循环的冷却液流量占比增大。结合成本和快速应对冷却系统阻力偏大的问题，建议小循环连接管路选择12.2 mm直角弯管状态，小循环流阻降低34.8%， 流经小循环的冷却液流量占比为36%。研究结果可为阻力评估及结构改进提供仿真数据参考。

Flow Resistance Analysis and Structure Improvement of Thermostat Components in Cooling System

The cooling system resistance of a motorcycle is too large, resulting in water leakage of the cooling system. After investigation, the preliminary reason is that the overall resistance of the radiator and thermostat pipeline is large. In order to study the flow resistance of thermostat components in this cooling system, CFD software STAR-CCM+ was used to simulate the flow field of thermostat components. The results show that flow resistance of small cooling circuit is 187 kPa when the thermostat is fully closed, which has a great influence on total resistance of the cooling system. In order to decrease flow resistance of small cooling circuit at closed state of thermostat, the influence of large thermostat, dual-thermostat and the connection pipe inner-diameter of small cooling circuit on flow resistance is studied. The results show that large thermostat and dual-thermostat can effectively reduce the flow resistance of small cooling circuit at the closed state of thermostat, but when the thermostat is fully open, the proportion of coolant flow flowing through small circulation increases greatly and the cost is high. Under the condition of the original thermostat, with the increase of connection pipe inner diameter of small cooling circuit, flow resistance of small circulation decreases significantly, and the proportion of coolant flowing through small circulation increases. The connection pipe inner-diameter of small circulation for this thermostat should not be greater than 13 mm. Combined with the cost and quick response to the problem of large resistance of the cooling system, it is recommended to select the connection pipe with 12.2 mm right angle elbow for small circulation. The flow resistance of small circulation is reduced by 34.8%, and the flow proportion of coolant flowing through small circulation accounts for 36%. The research results can provide simulation data reference for resistance evaluation and structural improvement of thermostat.