Abstract
Abstract
This paper deals with the influence of the discharge coefficient on fuel spray characteristics using diesel fuel. The discharge coefficient of injector DLL 25S834 is determined by running experiments on a device mounted to a direct injection M system of a NA diesel bus engine MAN D2 2566. Because of the difficulties related to its determination at small needle lift, some prediction of the discharge coefficient at the beginning of needle lift is needed.
Using the nozzle discharge coefficients, numerical simulation of fuel spray using commercial software Fire is performed. The numerical simulation of diesel fuel spray with different predicted discharge coefficient histories is performed at different engine pump speeds. The numerically obtained results are compared with experimentally obtained fuel spray and analyzed.
On the basis of agreement of the experimental and numerical results, the influences of discharge coefficient on injection and simulated fuel spray characteristics are discussed.
The most important role to improve engine characteristics plays the injection system. In order to reduce harmful diesel engine emission, it is necessary to control the injection as well as fuel spray characteristics to a great extent. For this reason, the injection and fuel spray characteristics have to be investigated.
Keywords: diesel engine, conventional injection system, discharge coefficient, spray, computational fluid dynamics