In off-highway machines, the separate engine compartment suppresses noise to meet regulations and spectator requirements. The enclosed engine compartment results in higher underhood temperatures, higher cooling heat loads, and increased charge air temperatures. Since higher temperatures can reduce component durability and life, analysis of underhood thermal conditions is important for identification of thermal hot spots and assurance of adequate air cooling. The product development cycle of design-analysis-simulation-test involves numerous iterations to come up with an acceptable design. Thus, rapid and accurate simulation techniques are desirable.
The objective of this study was to develop a 1-D thermal-fluid network model using commercial software FLOWMASTER. This 1-D model serves as a tool to predict/analyze the interactions of engine structure with air, coolant, and oil loops for machine thermal performance. Accurately modeling the engine thermal system requires both experimental and computational fluid dynamics (CFD) data, with boundary conditions obtained from well-controlled laboratory experiments. About 96% of the fuel energy was accounted for during the tests; 3-D CFD simulations were utilized in determining air flow fields and engine-surface heat fluxes.
With the thermal interactions modeled successfully, underhood-temperature predictions agreed within 10% of measurements for different inlet locations and airflow rates. Developing a package of 1-D and 3-D co-simulations is underway as followup of this work.