Unsteady gas dynamics and local heat transfer of pulsating flows in profiled channels mainly to the intake system of a reciprocating engine

Abstract

• The secondary vortex flows of pulsating flows in profiled channels were analysed. • The turbulence intensity of pulsating flows in profiled channels was determined. • The effects of profiled channels on heat transfer in an engine intake system have been established. • An assessment of the key indicators of a diesel engine with a profiled intake system was performed. This article presents the results of experimental research into the gas dynamics and heat transfer of pulsating air flows in an intake system with square and triangular channels, as well as data from bench tests of a diesel engine. The research was carried out on both a full-scale model of a piston engine and a test bench with a diesel engine. In the first stage, some detailed data on the gas-dynamic and heat exchange characteristics of pulsating flows in the intake system were obtained. It is shown that the gas-dynamic effects typical of square and triangular channels have a significant impact on the flow and heat-transfer characteristics. It is established that the intensity of the turbulence of pulsating flows increases to 22% in the intake system with profiled channels (increased small-scale turbulence), while the amplitudes of the spectrum of flow velocity functions decrease to 33% (suppression of large-scale oscillations). It is shown that a square or triangular channel in the intake system leads to an increase in air mass flow in the range of 5% to 12% compared to the base system. It was found that the increase in the heat transfer coefficient is from 3% to 25% when profiled channels are used. In the second stage, bench tests of a diesel engine with different intake system configurations were carried out to evaluate the technical and economic performance. It is established that the use of profiled channels in the intake system leads to an increase in diesel power of up to 15% compared to the basic modification (while the engine efficiency remains unchanged). The data obtained supplement existing information on the gas-dynamic and heat-exchange characteristics of pulsating flows in profiled channels and can be used in the development of new designs for piston engine intake systems.