A Study on Combustion in Direct-Injection Diesel Engines : 1st Report, In the Case of Shallow-Dosh Chamber

Abstract

To reveal the mixture formation and combustion in a shallow-dish type engine with a multi-hole nozzle, a high-speed photographic study has been made. Comparisons of the photographs taken under various conditions have let to the following results. Under no swirl condition, various kinds of gas motion are produced in the flame in the piston cavity soon after ignition. They govern the subsequent state of combustion, finally affecting the air-utilization in the later stages of combustion, and they are dependent on the diameter of the nozzle-hole as well on the direction of injection. When a swirl is employed, the radial extension of the spray is considerably reduced with its intensity, thereby the subsequent spread of the flame being suppressed. Unless a sufficient penetration of the spray is assured, air-utilization is poor in the peripheral space, leading to the so-called overswirling.