Experimental Study of Gas Dynamics and Heat Transfer of a Stationary Flow in Exhaust Pipelines with Different Cross-Sectional Shapes

Improving the process of cleaning the cylinder from exhaust gases has a significant impact on the operational and environmental performance of a piston engine. The purpose of the work was to assess the influence of the exhaust pipeline design on the gas dynamics and heat transfer of a stationary flow in the cylinder and exhaust system. The article obtained data on the flow structure in the cylinder and exhaust pipelines with different cross-sectional shapes. Additionally, the values of the turbulence number and heat transfer coefficient in the profiled exhaust pipelines were determined. Cross sections in the form of a circle (base), square and equilateral triangle were used. The thermal imaging method and the thermal anemometry method were used to determine the gas-dynamic and heat transfer characteristics of stationary flows. The studies were carried out on full-scale experimental stands. It has been established that the cross-sectional shape of the exhaust pipeline has virtually no effect on the flow structure in the cylinder. Differences in flow patterns in exhaust pipes with different cross-sections for different air flow rates through the system were shown. It was revealed that there was a decrease in the flow turbulence number in the exhaust system for profiled pipelines by an average of 25% compared to the base system. It was also found that the use of profiled pipelines led to suppression of heat transfer in the exhaust system by up to 34% compared to the base system. The obtained data can be used for the design and modernization of exhaust systems of piston engines with and without a turbocharging system.