Experimental Assessment of Flow Structure in a Cylinder During Air Flow Through Poppet Valves of Different Configurations

Data are presented on the gas-dynamical structure of flow in the cylinder when it is filled through poppet valves with heads in the form of a circle and a square. The studies were carried out on a laboratory setup simulating a piston internal combustion engine. The air flow through the gas-dynamical system of the engine was carried out in a stationary mode with an initial speed of 8 to 41 m/s. Thermograms of the flow structure were obtained for two control sections of this system using the thermal imaging method. It has been established that the configuration of the cylinder valve head exerts a significant impact on the structure in it and that in a cylinder with a round valve there are pronounced stagnant zones. It has been shown that the use of valves with a square head ensures more uniform filling of the cylinder with air throughout its entire volume compared to a traditional round valve. The data obtained can be useful for refining mathematical models of the process of cylinder filling and for developing new methods of modernizing valve assemblies of piston machines.