The breathing of four stroke internal combustion engines

A study or the breathing performance of four-stroke internal combustion engines with particular emphasis on heat transfer during induction is presented. An experimental study into inlet port heat transfer has been conducted, and the following law has been established for a compression ignition engine assuming a quasi-steady heat transfer process : Nu = 3.155 Re 0.53. A similar study of the heat pick-up of a spark ignition engine inlet port has failed to produce such a relation. The Nusselt number has been found to increase with Reynolds number initially and then decrease, Figs. (47, 48, 49). This was the case even when this engine was operated with gaseous fuel suggesting that fuel evaporation was not the cause. Theoretical calculations indicats the inlet port heat transrer is very important and reduces the volumetric efficiency by about 5.5% on average. The combined reduction in volumetric efficiency due to inlet port and cylinder heat transfer amounts to l4% on average, depending on the engine speed. An extensive literature survey of the various aspects of induction is also presented. The differential equations involved were solved numerically using an electronic digital computer.