CFD modelling on flow field characteristics of engine cooling water jacket and its cooling performance improvement based on coolant transport path analysis method

Abstract

Reasonable coolant flow distribution and its heat transfer coefficient (HTC) distribution are of great significance to the cooling performance of water-cooled engine. Therefore, the present paper proposes a coolant transport path analysis method aiming at analyzing coolant velocity distribution and optimizing the coolant flow characteristics of water jacket based on Computational Fluid Dynamics (CFD), with particular emphasis on the assessment of coolant flow velocity distributions of high-temperature area of engine head water jacket. First, the coolant flow characteristics of a single-cylinder water jacket is investigated and it is found that coolant velocity of exhaust bridge is less than 1.5 m/s and the HTC distribution of water jacket under three flow conditions of 15 L/min, 25 L/min and 35 L/min have a small area reaching 5000 W/(m2∙K). Some areas have no coolant flow and the mass flowrate distribution of each gasket hole is unreasonable, proving that original water jacket structure has some shortcomings and need to be optimized. Based on coolant transport analysis, an improved design of the single cylinder water jacket is proposed and HTC distribution of improved water jacket meet cooling requirements that HTC in high heat load area are above 5000 W/(m2∙K). The coolant transport path analysis method for optimizing coolant flow characteristics of water jacket proves to be an effective way through successful application and remarkable achievement in the other single-cylinder water jacket and two-cylinder water jacket that coolant flow distribution become more reasonable and coolant velocity of high-temperature areas are bigger than 1.5 m/s.