Effect of the number and position of nozzle holes on in- and near-nozzle dynamic characteristics of diesel injection

Abstract

Despite the fact that all modern diesel engines use multi-hole injectors, single-hole injectors are frequently used to understand the fundamental properties of high-pressure diesel injections due to their axisymmetric design of the injector nozzles. A multi-hole injector accommodates many holes around the nozzle axis to deliver adequate amount of fuel with small orifices. The off-axis arrangement of the multi-hole injectors significantly alters the inter-and near-nozzle flow patterns compared to those of the single-hole injectors. This study compares the transient needle motion and near-nozzle flow characteristics of the single-and multi-hole (3-hole and 6-hole) diesel injectors to understand how the difference in hole arrangement and number affects the initial flow development of the diesel injectors. A propagation-based x-ray phase-contrast imaging technique was applied to compare the transient needle motion and near-nozzle flow characteristics of the single-and multi-hole injectors. The comparisons were made by dividing the entire injection process by three sub-stages: opening-transient, quasi-steady and closing-transient.

Injection systems in diesel engines and their theoretical-experimental study: a review

“…On the other hand there are works that follow the second approach as the work of Amin Yousefi [23] that models different types of injection for heavy services at low loads or that of Madjid Birouk [24] that analyzes the effect of the injection delay on the Emissions, both choose to follow the system of Navier-stokes equations, others like Pang Kar [25] choose to follow a Eurelian stochastic method to know how the ignition flame develops. In the case of the third approach we have works such as Rao [26], which measures the effect of post-injections on emissions in small diesel engines with optical exams to experimental designs or the work of Seoksu Moon [27] who opts for the use of x-rays to discover how the injector needle affects the flow through each orifice of the injector in single hole, 3-hole, and 6-hole injectors. In the fourth approach we find works such as Poorghasemi [28], which achieves a model that simulates 3D combustion and predicts emissions for direct injection (DI) and the controlled compression ignition method (RCCI) or Dezhi work Zhou [29] that studies the effect of injection timing on the start injection rate on emissions and combustion characteristics in a direct injection compression engine (DICI).…”

A Review of Engine Fuel Injection Studies Using Synchrotron Radiation X-ray Imaging

“…As shown in Fig. 16, ultrafast X-ray absorption and phase-contrast imaging can monitor the near-field spray liquid core morphology with high spatial and temporal resolution [40]. However, it is still challenging to obtain quantitative information from such spray morphology images to study the fuel spray characteristics.…”

“…The measurement setup is calibrated using cannulas of different diameters filled with n-heptane. Based on the density of n-heptane and the size of the cannulas, the Fuel spray morphology images obtained with ultrafast X-ray phase-contrast imaging [40] transmission coefficient can be calculated by applying the Lambert-Beer-Bonquer law. Figure 18b plots the X-ray transmission as a function of the thickness of the n-heptane samples.…”

Sensitivity analysis of the dynamic response of an electronic fuel injector regarding fuel properties and operating conditions

“…Electronic fuel injectors play an indispensable role in HPCR fuel injection systems and interest numerous researchers to improve their performance. A lot of work has been undertaken in the nozzle area, such as the nozzle structure types [1][2][3], the hole numbers and arrangements [4][5][6][7] and the internal cavitation [8][9][10][11] of orifices. They have been thoroughly studied because they have a direct effect on the fuel injection and atomisation.…”