The Spray Performanceanalysis Of Diesel Injector Nozzle Based On Corrosion Factors

Diesel engines must meet the requirements of increasingly stringent legislationregarding power, fuel consumption, noise and exhaust emissions. To comply withthese regulations, engines must be equipped with high-performance fuel injectionsystems. As a precision part of the fuel injection system in diesel engine, the nozzledirectly affects the spray quality of fuel, determines that whether the enginecombustion and emissions performance are good or bad. There are many factors thatinfluencing the spray characteristics of nozzle, including corrosion, erosion, wear,cavitation erosion and their interactions which will damage the nozzle mechanicalproperties, indirectly affect the spray characteristics of nozzle. At present, theinfluence of corrosion on the nozzle spray performance is studied less both at homeand abroad, this article consider the low speed diesel engine as the object, mainlystudying the mechanism of low temperature corrosion caused by the heavy oil anderosion corrosion, analyzing the spray performance of diesel engine nozzle theyeffecting on. The research work and conclusions include the following contents:（1）The corrosion characteristics of heavy oil are discussed. First, doelectrochemical tests on the nozzle low temperature corrosion GCr15under differenttemperatures in heavy oil medium, and measure the corrosion rate, the results showthat the conductivity of heavy oil is very bad, the polarization curve is irregular andcurrent density rises as the temperature, there is almost no corrosion. At the same time,do static immersion test on the nozzle material for a long time, and observe thesurface morphology, founding that the heavy oil is not corrosive to metal, and theGCr15material in air and inferior light diesel oil is easy to cause pitting.（2）Conducting the low temperature corrosion simulation experiment, analyzethe low temperature corrosion mechanism and law, do corrosion test of nozzlematerial GCr15in sulphuric acid medium of different concentration, comparing thecorrosion resistance between45carbon steel and304stainless steel. The results showthat the low temperature corrosion do greater damage to nozzle, the nozzletemperature is better to be controled at120℃to180℃, choose the hardness stainlesssteel material. （3）The erosion mechanism is discussed and the erosion corrosion under thecondition of cavitation flow inside the nozzle is conducted the numerical simulationand analysis by Fluent software, the two-dimensional tube model of pintle nozzles isestablished, the flow state inside the nozzle hole is simulated and the change rule ofwall shear stress is analyzed respectively under the condition of different fuel oilviscosity, inlet pressure, back pressure and the entry rounded.（4）Analyzing the effect of corrosion on spray performance of the diesel enginenozzle. The results show that the low temperature corrosion would produce greatnegative influence on diameter and roughness of spray nozzle hole, seriouslyinfluencing the spray characteristics of nozzle. Erosion corrosion is a long and slowprocess, but the influence on roughness of wall material should not be ignored.