Study of new prototype pintle injectors for diesel engine application

Taghavifar

et al. 2020

Fuel

In the current paper, an investigation of the supersonic flow effect on shockwave generation and diesel spray penetration scaling has been performed. For this purpose, spray visualization tests have been carried out in a constant-pressure chamber at room temperature using shadowgraphy technique. Two working gases have been used: nitrogen, with similar thermodynamic characteristics to the engine environment, and sulfur hexafluoride, aimed at producing supersonic conditions at moderate injection pressure values. A total of 60 operating points, including different nozzle geometries, injection pressures and chamber densities have been studied. From the visualization study, two different kinds of shockwaves have been detected: normal or frontal, for moderate spray tip Mach (between 1 and 1.5); and oblique, when the Mach is higher than 1.5. The penetration results show that, for the same injection conditions in terms of injection pressure and chamber density, the spray propagation is equal for SF6 and N2 when the spray is on subsonic conditions, while penetration is higher for SF6 when supersonic velocity is reached. This behavior has been related to the density gradient appearing across the shockwave. A new methodology to extrapolate supersonic penetration from the well-known subsonic penetration law has been proposed, showing good agreement with the experimental results.

Section: Methodsmentioning

confidence: 99%

Scaling spray penetration at supersonic conditions through shockwave analysis

Salvador

Taghavifar

et al. 2020

Fuel

“…conditions, it has to be considered also that full spray evaporation is reached after a certain distance from the nozzle tip. This distance is called stabilized liquid length, and depends mostly on the orifice effective outlet diameter, the spray angle, the fuel properties and the ambient temperature [28][29][30][31][32].…”

Section: Uthmentioning

confidence: 99%

Experimental investigation of the effect of orifices inclination angle in multihole diesel injector nozzles. Part 2 – Spray characteristics

Payri

Salvador

et al. 2018

Fuel

Diesel spray development is a key research topic due to its impact on the combustion characteristics. On the current paper, the effect of the orifices inclination angle on the spray penetration characteristics is evaluated. For this purpose, three nozzles with included angles of 90, 140 and 155 degrees are selected. Visualization tests are performed on a room-temperature constant-pressure vessel pressurized with a high-density gas (SF6), in order to reproduce the density conditions inside the combustion chamber at the start of the injection event. Both frontal and lateral Mie-scattering visualization are used, depending on the particular nozzle configuration. Results show how the spray penetration is slower as the inclination angle increases, which is linked to its lower nozzle outlet 2 velocity. A statistical correlation of the spray penetration as a function of the area and velocity coefficients is obtained and discussed.

“…Diesel combustion is highly influenced by the fuel injection system performance. For this reason, significant research effort has been made into analyzing the influence of the injector nozzle geometry into the injector hydraulics [1][2][3], spray formation [4][5][6][7] and combustion [8][9][10]. In this sense, one of the aspects that can be explored is the shape itself of the nozzle orifices.…”

Section: Introductionmentioning

confidence: 99%

Impact of counter-bore nozzle on the combustion process and exhaust emissions for light-duty diesel engine application

Payri

International Journal of Engine Research

Monsalve‐Serrano

et al. 2018

Self Cite

This article describes the main results of an investigation about counter-bore injector nozzle impact on the combustion process in a modern Euro 6 diesel engine. First, hydraulic and spray visualization tests have been performed, showing a potential advantage of such nozzle design in fuel–air mixing efficiency. Then, combustion performance has been assessed on a GM-designed 1.6-L four-cylinder engine. The engine has been installed on a dynamometric test bench and instrumented with an AVL cylinder pressure transducer for heat release rate analysis, as well as HORIBA MEXA gas analyzer for exhaust emissions and AVL 415 Smoke Meter. Engine efficiency and emissions have been analyzed on four different part-load steady-state points, representative of New European Driving Cycle and Worldwide harmonized Light duty Test Cycle certification cycles, and covering engine speeds from 1250 to 2000 r/min and brake mean effective pressure between 0.2 and 1.4 MPa. Results of indicated analysis show that counter-bore nozzles have significant differences in terms of pilot injection combustion at low load points, which in turn lead to a better ignition and shorter combustion of the main injection. In addition, an improvement of diffusive combustion is observed as load increases. Because of both, fuel consumption is reduced by approximately 1% with respect to a standard nozzle. Finally, an appreciable decrease in engine exhaust emissions has been recorded, especially in terms of particulate matter and hydrocarbon emissions. This reduction has been linked to the improvement of fuel–air mixing promoted by the counter-bore nozzle previously observed.