Nozzle Hole Diameter Research Articles

Experimental investigation into simulated aging effects of common-rail injector nozzles: Influences on injection rate, spray characteristics, and engine performance

Emission performance of combustion engines has gained outstanding importance with both legislators and customers over the past years. Injector aging, such as nozzle wear or coking, results in the deterioration of injection and emission parameters. In this study, the influences of aging effects on injection rate, fuel spray as well as engine performance and emissions were assessed. Nozzles, which had previously been operated in a vehicle engine and were likely to have suffered from aging, showed no aging-induced characteristics during injection rate and spray measurements and were not investigated further. Therefore, nozzles with different nozzle hole diameters were utilized to simulate the different aging effects. Injection rate measurements demonstrated, that for smaller energizing times, a nozzle with smaller nozzle holes can deliver a higher injected mass than a nozzle with bigger nozzle holes. The adaptation of energizing time or injection pressure demonstrated the potential to compensate the change in engine load due to smaller or bigger nozzle holes. For bigger nozzle holes, the adaptation of injection pressure in order to restore the target load returned lower NOx emissions, whereas the adaptation of the energizing time always yielded lower soot emissions compared to the reference nozzle. For small nozzle holes, the optimization of the start of energizing reduced specific NOx emissions without increasing specific soot emissions. The comparison of measured injection rate and fuel spray characteristics to the ones reported in literature confirms the possibility of simulating nozzle wear by increased nozzle holes and coking by smaller nozzle holes. The results of this study are of vital interest to the research of aging effects and add useful knowledge about compensation methods for nozzle aging.

Effects of Injection Pressure and Nozzle Diameter on Flame Structure of Diesel Spray of Agriculture Machine.

Due to the mixing process of fuel and air in diesel engine, various diesel spray devices have been developed. More than one hundred years of development have made these diesel engines controllable and efficient, resulting in cleaner performance and enhanced fuel consumption. Still series of features: engine geometries, fuels, chemical-kinetics, in-cylinder flow, combustion process, sprays and fuel-air mixture formation must be investigating to reduce engine emissions, and increase performance of the engine. Alteration in fuel droplet and fuel-air mixture is one of the advanced elucidations in diesel engine. The injection pressure, ambient temperature and nozzle diameter can alter the fuel droplet and flame during combustion. The effects of injection pressure and nozzle hole diameter on flame structure and of impinging diesel spray were investigated. CFD software ANSYS IC Engine (Fluent) V-18 was employed to investigate such effects. For the injector nozzle having 0.18 mm diameter, injection pressure (140 MPa) with ambiet temperature 500 °K generates appreciably larger flame structure. Impinging spray flame of nozzle hole 0.1 mm shows much smaller size. The movement of the high velocity region was demonstrated to be at the injector tip in the beginning of injection period (340° CA) which accompanied with the high pressure region. That satisfy the fact which is as spray cone be larger, the spray generates more and more swirl dominant flow that lead to higher evaporation rate. Furthermore, the maximum velocity of injection under 70 MPa was decreased by 15.1093% than its value under 140 MPa. That satisfies the physical concept of pressure to velocity relation for compressible flow. Also, the maximum velocity of flow field with 0.1mm, injector diameter, was decreased by 26.5425% than its value in the case of 0.18 mm diameter. Keywords: Agriculture Diesel Spray Machine, Combustion Chamber, Flame Structure, Injection Pressure, Nozzle Diameter, Velocity Contours

Modeling diesel spray tip and tail penetrations after end-of-injection

Zero-dimensional (0-D) modeling of spray development plays increasingly significant roles in the model-based optimization of parameter designs and control strategies in diesel engine systems. Partially premixed low temperature diesel combustion that has been deemed essential in simultaneous reductions in the nitrogen oxides (NOx) and soot emissions usually features ignition occurrence after the end of fuel injection (EOI). However, so far modeling of the spray development after the EOI is far from adequate. Particularly, a theoretical model for the spray tail penetration is still absent. The objective of this paper is therefore to develop the 0-D model for both diesel spray tip and tail penetrations. The model of spray tip penetration after the EOI is based on the existing models, and the model constant is further developed. The mathematical expression of spray tail penetration is newly deduced with the discrete control volume method. These models are validated against the experimental spray data with varied ambient densities, injection pressures and nozzle hole diameters using the high-speed shadowgraphy and the constant volume chamber. The calculated results by the models agree very well with the experimental ones. The spray tip penetration exhibits a t dependence at the initial stage of injection, a t1/2 dependence at the later stage, and a (t−ti)1/4 dependence after about two injection durations from the start of injection (SOI). While the spray tail penetration is independent of the fuel injection pressures, it exhibits a (t−ti)1/2 dependence. Since the spray tail penetration rate is rather slower than the spray tip, the spray development after the EOI shows a trend with remarkable length extension, causing the quick fuel-air over mixing. These results are believed to be valuable reference for researchers or engineers who are considering the model-based design and control strategy development for diesel engine systems.

Visualization Investigation of the Influence of Chamber Profile and Injection Parameters on Fuel Spray Spreading in a Double-Layer Diverging Combustion Chamber for a DI Diesel Engine

The double-layer diverging combustion chamber (DLDC chamber) aims to improve the fuel–air mixing formation and promote in-cylinder air utilization by changing fuel spray spreading characteristics. In order to investigate how the DLDC chamber profile and injection parameters affect the fuel spray spreading, visualization of fuel injection and impingement tests were carried out on two different DLDC chambers with different fuel injection parameters. The visualization test results showed that double-layer fuel spray spreading was obtained in the two DLDC chambers and the peripheral top clearance of each chamber was utilized efficiently. The DLDC chamber with a 50% upper layer volume provided a larger fuel spray distribution region after the start of injection. The DLDC chamber with a 70% upper layer volume obtained a larger fuel spray distribution region with better top clearance utilization at the later stage of injection. The injection parameters mentioned in this research showed significant effects on the fuel spray spreading in the DLDC chamber. Increasing the injection pressure provided a larger fuel spray distribution area at the beginning of injection. Decreasing the nozzle hole diameter had a positive influence on obtaining a larger fuel spray distribution. Advancing the injection timing enabled the enlarging of the fuel distribution region.

Experimental investigation of the combustion characteristics of Mahua oil biodiesel-diesel blend using a DI diesel engine modified with EGR and nozzle hole orifice diameter

Engine modification through reducing nozzle hole diameter (NHD) (i.e., from the base value of 0.28 to the modified value of 0.20 mm) has been shown as an effective strategy in improving engine performance, combustion, and emission parameters. However, it has also led to substantial increases in NOx emission as a major shortcoming. In light of that, the present study was aimed at overcoming this challenge through the application of a partially-cooled exhaust gas recirculation (EGR) system. More specifically, Mahua oil biodiesel-diesel blend (B20) and neat diesel were tested on a modified single cylinder diesel engine under five different engine loads (i.e., 2.46, 4.92, 7.38, 9.84, and 12.3 kg) and in the presence of varying EGR rates (i.e., 10, 20, and 30%). The results obtained revealed that the performance, combustion, and emission characteristics of the modified engine (3-hole nozzle with an orifice diameter of 0.20 mm) were improved for both neat diesel and B20 except in the case of NOx, in comparison with those of the conventional diesel engine (3-hole nozzle with an orifice diameter of 0.28 mm). The considerable increases in NOx emissions caused by the smaller orifice NHD could be successfully compensated for through the implementation of the partially-cooled EGR. Overall and based on the findings of the present study, the proposed engine modification in the presence of partially-cooled EGR rate of 10% could be recommended as efficient combustion conditions for 20% blend of Mahua oil biodiesel and diesel. However, further increments in the EGR rate and in particular at higher loads, adversely affected the performance and emission characteristics of the modified engine due to the recirculation of high amounts of unburnt soot, CO2, H2O, as well as of O2 deficiency.

Scaling fuel sprays for different size diesel engines

Diesel engines are widely used not only for heavy-duty vehicles such as ships and trucks but also for light-duty passenger cars, with a wide range of bore diameters. Since development of a new diesel engine is usually expensive and time consuming, the ability to accurately predict engine performance from existing models can reduce the resources and time required in the engine development procedure. However, so far knowledge on scaling diesel engines is far from adequacy, particularly for spray combustion processes. In this paper, two injectors with nozzle hole diameters of 0.11 mm and 0.14 mm are adopted for scaling fuel sprays under the non-evaporating conditions based on the three similarity rules. Firstly, the existence of similarity is theoretically analyzed in diesel fuel sprays of both free injection and impinging upon a wall. Then, the similarity of diesel injection rate is experimentally verified by using the Bosch long tube method. Finally, the similarity of spray angle, tip penetration length, excess air ratio and impinging spray characteristics are investigated under various injection pressures and ambient densities in an optically accessible constant volume vessel by the high-speed shadowgraphy. The theoretical analysis and experimental results reveal that the similarity rule keeping the injection pressure constant is more preferable for scaling the spray angle, tip penetration length and excess air ratio, while the other two similarity rules with reduced injection pressure result in narrowed spray angle and increased spray tip penetration length. With respect to the post-impingement behavior, although the spray from the large-hole nozzle impinges upon the wall later than those of the small-hole nozzles with the speed rule and the lift-off rule, the rebound height of the large-hole nozzle is higher than those by the small holes with the speed and the lift-off rule. The mechanism of the above phenomena is discussed in depth.

Influence of different nozzle hole orifice diameter on performance, combustion and emissions in a diesel engine

In this article, the experimental tests were carried out to explore the performance, combustion and emissions by modifying the different nozzles hole size injectors such as (3 holes × Ø = 0.20 mm (modified)), (3 holes × Ø = 0.28 mm (Base)) and (3 holes × Ø = 0.20 mm (modified)). The experiments are performed on Kirloskar 4-stroke computerised solitary cylinder diesel engine fuelled with diesel at 1500 rpm, water-cooled direct injection diesel engine with eddy current dynamometer with the standard injection timing of 23° bTDC with an injection pressure of 210 bar was maintained constant throughout the experiment. From the results, it was pointed out that in all the three different nozzles (3 holes × Ø = 0.20 mm (modified)) improves the vaporisation, atomisation and air-fuel mixing are resulting in a shorter duration. The impressive results are seen in the performance, combustion and emissions. The only negative aspect is the NOx increasing with small orifice Nozzle Hole Diameter.

Experimental study effect of diameter and number of spray nozzle holes on counterflow cooling tower to improve cooling effectiveness

The cooling system is an essential part of the production process within the plant. In the cooling system using cooling tower, efficiency can be improved by increasing the effectiveness of cooling through nozzle modification. This study aims to determine the effect of diameter and number of nozzle holes on cooling effectiveness. The data were taken from the experiments using prototype of counterflow cooling tower with dimension of high x cross-sectional area are 120 cm x 40 cm x 40 cm. Diameter varied by 1; 1.5; and 2 mm, while the number of nozzle holes 4; 8; 16. The results show that the highest cooling effectiveness was achieved at nozzle diameter 1.5 mm with the number of holes 8 that is 38.77%.

Experimental Investigation on the Integration of Raceway Pond and Airlift Pump for Microalgal Cultivation

This work proposed an integration of raceway pond and airlift pump (RWPAP) for microalgae cultivation. Therefore, the proposed reactor was evaluated under various configurations of liquid depth in the raceway reactor, air flow rates, two riser airlift pump diameter and two nozzle hole diameter. The minimum air flow rate necessary for circulating medium in the RWPAP reactor in addition to the liquid velocity in the reactor was investigated. These parameters as well as the power consumption were determined in order to achieve the maximum efficiency and effectiveness configuration. The maximum effectiveness configuration of the RWPAP system was achieved at the water depth 40 cm, air flow rate 0.83 L min -1 , injector hole diameter 0.5 mm and tube diameter 0.75 inch that produced the maximum ratio velocity to power consumption with near one tenth of power consumption of the maximum efficiency configuration. At these configurations, the microalga Dunaliella Salina was cultivated in the natural culture medium from the Maharlu Salt Lake, southeast of Shiraz, Iran in order to achieve commercialization and reduce cultivation cost and the results showed that the effectiveness configuration had better biomass productivity, CO 2 utilization efficiency, power consumption and water evaporation rate compared to another configuration. The effectiveness configurations gave comparable batch biomass productivity (0.096 g L -1 day -1 ) and 25.37% CO 2 utilization efficiency, but around five-times higher biomass productivity per unit power input (2.21 g W -1 day -1 ) than reported for the modified airlift reactors. Furthermore, the β-carotene content and composition of fatty acids were evaluated.

High-resolution X-ray tomography of Engine Combustion Network diesel injectors

The flow inside direct-injection diesel nozzles is strongly influenced by the local geometry. Deviations from the design geometry and nonuniformities along the fuel’s flow path can alter the expected spray behavior. The influence of small-scale variations in the internal geometry is not well understood due to a lack of data available to experimentalists and modelers that resolve such features. To address the need for more accurate geometry measurements that also quantify the error bounds on manufacturing variability, the 7-BM beamline of the Advanced Photon Source at Argonne National Laboratory has been customized to obtain high-resolution X-ray tomography of injection nozzles. In this article, we present results for several diesel injectors provided by the Engine Combustion Network. The imaging setup was optimized to measure dense metallic samples at high signal-to-noise ratio using projection imaging. To improve contrast, multiple images were recorded at each rotation angle. Phase shifting effects, which amplify the uncertainty in locating nozzle boundaries, were minimized by reducing the propagation distance of the X-rays between the nozzle and detector. Such improvements to the imaging technique enabled the nozzle hole diameter to be measured with an accuracy of 1.8 µm, which takes into account the pixel resolution as well as the properties of the imaging setup and the geometric analysis. The high spatial resolution allows the nozzle hole inlet corner radius to be azimuthally resolved. For the sample set under consideration, these new measurements reveal that non-hydroground injectors have a distribution of radii which typically vary by more than a factor of two. An azimuthally varying radius of curvature at the hole inlet is expected to result in highly asymmetric cavitation. Skeletal wireframe models of the nozzle hole geometries suitable for computational fluid dynamics mesh generation have been developed, in addition to full three-dimensional isosurfaces; these data have been made publicly available online.

A CFD simulation study of air-lift artificial upwelling based on Qiandao Lake experiment

The application of artificial upwelling technology could increase the primary marine productivity by bringing nutrient-rich subsurface water to surface. Although the artificial upwelling has been extensively studied, few numerical simulation studies on artificial upwelling device parameters, such as nozzle type, injection depth and injection hole diameter, have been conducted. This paper establishes a computational fluid dynamics (CFD) model to theoretically analyze how the upwelling efficiency were influenced by injection nozzle type, diameter of injection hole and injection depth. The comparison between the simulation results and the corresponding experimental data obtained in Qiandao Lake experiments firstly proves the accuracy of the predictions of CFD model in terms of upwelling efficiency via changing the parameters of the artificial upwelling device; secondly, it also indicates that the circular type of an air injection nozzle installed in deeper water depth with larger injection holes brings more deep water to the surface. It is believed that this study may shed some light on the improved design of an artificial air-lift upwelling device.

The effect of hydrogen injection parameters on the quality of hydrogen–air mixture formation for a PFI hydrogen internal combustion engine

To research the quality of the hydrogen–air mixture formation and the combustion characteristics of the hydrogen fueled engine under different hydrogen injection timings, nozzle hole positions and nozzle hole diameter, a three-dimensional simulation model for a PFI hydrogen internal combustion engine with the inlet, outlet, valves and cylinder was established using AVL Fire software. In the maximum torque condition, research focused on the variation law of the total hydrogen mass in the cylinder and inlet and the space distribution characteristics and variation law of velocity field, concentration field and turbulent kinetic energy under different hydrogen injection parameters (injection timings, nozzle hole positions and nozzle hole area) in order to reveal the influence of these parameters on hydrogen–air mixture formation process. Then the formation quality of hydrogen–air mixture was comprehensively evaluated according to the mixture uniformity coefficient, the remnant hydrogen percentage in the inlet and restraining abnormal combustion (such as preignition and backfire). The results showed that the three hydrogen injection parameters have important influence on the forming quality of hydrogen–air mixture and combustion state. The reasonable choice of the nozzle hole position of hydrogen, nozzle hole diameter and the hydrogen injection time can improve the uniformity of the hydrogen–air mixing in the cylinder of the hydrogen internal combustion engine, and the combustion heat release reaction is more reasonable. At the end of the compression stroke, the equivalence ratio uniform coefficient increased at first and then decreased with the beginning of the hydrogen injection. When hydrogen injection starting point was with 410–430°CA, equivalence ratio uniform coefficient was larger, and ignition delay period was shorter so that the combustion performance index was also good. And remnant hydrogen percentage in the inlet was less, high concentration of mixed gas in the vicinity of the inlet valve also gathered less, thus suppressing the preignition and backfire. With the increase of the distance between the nozzle and the inlet valve, the selection of the hydrogen injection period is narrowed, and the optimum hydrogen injection time was also ahead of time. The results also showed that it was favorable for the formation of uniform mixing gas when the nozzle hole diameter was 4 mm.

Influential factors’ correlation analysis upon common rail system fuel injection quantity for diesel engines

The coherence of the fuel injection quantity determines the working stability of the common rail system. The variations in the parameters of the common rail injector have significant influence on coherence of the fuel injection quantity of the system. The bond graphs for the main components of the common rail injector were proposed, respectively, based on the bond graph methodology in this article. The fuel injection quantities of the system at different rail pressures and injection pulse widths had been obtained by numerically solving and programming the obtained state equations in MATLAB. The predicted results of the fuel injection quantity by the model are in excellent agreement with the experimental measurements which were obtained from a test bench. Through the correlation analysis of the influential factors on the fuel injection quantity, the correlation coefficients between the fuel injection quantity and the single influential factor and quadratic influential factor at different rail pressures and injection pulse widths were obtained, respectively. Moreover, the variation characteristics of correlation between the fuel injection quantity and its influential factors had been analyzed in detail. The results show that the nozzle hole diameter and the inlet orifice diameter are the main influential factors on the fuel injection quantity among the selected parameters. The quadratic factors under the action of the parameter itself and the quadratic factors under the interaction between the delivery chamber diameter and nozzle hole diameter, needle seat semi-angle and needle cone semi-angle, nozzle hole diameter and inlet orifice diameter and inlet orifice diameter and outlet orifice diameter have significant effect on the fuel injection quantity, and they are the main influential factors on the fuel injection quantity among the quadratic factors.

Study on LTC for light duty engines – Part 2 – Spray enhancements

This paper presents the 2nd part of a study on low temperature diffusive combustion in a small HSDI (High Speed Direct Injection) engine with the objective of avoiding simultaneously NOX and soot formation, aiming to extend the range of operation conditions where this combustion strategy has been achieved and. Also, it was intended to reduce CO and HC emissions, considered very high in the 1st part of the tests. New hardware configuration was chosen in order to improve air entrainment in the lift-off length such as increasing injection pressure, reducing fuel injection rate and nozzle hole diameter. Also, a parametric study on the behavior of in-cylinder air thermodynamic characteristics towards the diffusion-flame low temperature combustion was also carried out in order to evaluate the important aspects of each one and observe how the LTC range has been extended.The strategy is based mainly in a significant reduction of the equivalence ratio at the lift-off length cross section and the combustion temperature, maintaining the conventional mixing controlled diesel jet structure. In this 2nd part of the study, injection pressure was increased and new nozzles with reduced holes were used to enhance air entrainment and the injection rate was reduced to extend the duration of diffusion-flame combustion phase.The new proposal allowed extending Diffusion-flame LTC range, being possible to achieve this combustion modality with higher air temperature which lead to considerable reduction in HC, CO and combustion noise while NOx and Soot remained insignificant.

A comprehensive study on the factors affecting near-nozzle spray dynamics of multi-hole GDI injectors

In order to improve the engine thermal efficiency with reduced emissions, substantial studies have been carried out to investigate the factors affecting the fuel spray characteristics such as nozzle geometry, fuel property, and injection and ambient conditions. However, most of the previous studies have focused on the macroscopic structures of the fuel sprays, but detailed structures of internal spray dynamics have not been thoroughly investigated, especially in the near-nozzle region. In this study, the effects of critical injection parameters such as injection pressure, ambient density, fuel, nozzle hole diameter and length on the near-nozzle spray dynamics of multi-hole gasoline-direct-injection injectors were investigated using X-ray phase-contrast imaging and visible light imaging. Then, the scaling potential of the near-nozzle spray dynamic structure under various injection parameters was surveyed based on the gas jet theory. The results showed that the density ratio of the fuel and surrounding gas and spray angle are the governing factors of the near-nozzle spray dynamic structure. By introducing the governing factors as the scaling variables, the near-nozzle spray dynamic structure under various injection parameters can be scaled with near 90% correlation performance. However, the scaled dynamic path in the near-nozzle region is different with that of the gas jets that requires modifications of conventional gas-jet-based dynamics models for application to the near-nozzle region.

Investigation of the combustion process of hydrogen jets under argon-circulated hydrogen-engine conditions

The feasibility of argon-circulated hydrogen engines for use in vehicles was recently investigated. The substitution of the noble gas argon (Ar) as the working gas in a hydrogen engine led to the realization of a zero-emission, high-efficiency engine that allows low-ignitability hydrogen to ignite instantaneously after injection. The objective of this study was to investigate the combustion processes of hydrogen jets under argon-circulated hydrogen-engine conditions. Experiments were conducted in a constant-volume combustion vessel under varying conditions with respect to atmosphere, oxygen concentration, injection pressure, ambient temperature, and nozzle-hole diameter. Furthermore, the ignition characteristics and the combustion processes of the hydrogen jets were observed using high-speed shadowgraph images. Under short ignition delay conditions, the experimental results for the Ar–O2 atmosphere indicated a lower heat-release rate, which continued to the end of the injection and resulted in a longer combustion period, whereas the heat-release rate under the air (N2–O2) atmosphere terminated simultaneously with the end of the injection. The ignition delay for the hydrogen jet under an Ar–O2 atmosphere increased with decreasing ambient temperature, similar to the behaviour observed under the air atmosphere. Other fundamental characteristics that may help control the operation of argon-circulated hydrogen engines were obtained and discussed.

Influence of nozzle hole diameter and orifice diameter on dme spray to get the similar heat value with diesel spray using the constant volume chamber

Low heating value (LHV) of di-methyl ether (DME) is lower than that of diesel. To get the similar heat value with diesel from the diesel engine operation, single injection quantity of DME should be increased. This investigation was tried to increase the injection quantity of DME by the modified diesel injector and investigated the penetration length and spray angle of DME spray. DME was injected by using three-type modified diesel injectors those nozzle-hole diameters (Injector 1: 1.66 mm, Injector 2 and 3: 0.25 mm) and orifice diameters were different (Injector 1 and 2: 0.6 mm, Injector 3: 1 mm). Spray characteristics of DME was investigated with a various ambient pressures (2.5, 5.0 MPa) in the constant volume chamber and a fuel was injected by varied injection pressure from 35 to 70 MPa by interval of 5 MPa using a DME common rail fuel injection system. The result shows that DME injection quantity by Injector 3 was 1.69 ~ 2.02 times larger than that of diesel injection quantity by Injector 1. In this case, DME spray got the similar heat value compared with diesel spray. The penetration speed of DME spray by Injector 3 was the fastest, thus when the spray development was end, the penetration length of DME spray by Injector 3 was the longest compared with the other cases. In case of the spray angle, Injector 2 and 3 had the similar spray angle and these were larger than that of diesel and DME sprays by Injector 1. As the result, Injector 3 was the solution for how to solve the low heating value of DME.

Analysis upon fuel injection quantity variation of common rail system for diesel engines

Fuel injection quantity variation of common rail system has effect on the stability and reliability of diesel engines. For purpose of investigating the influence rule and mechanism of fuel injection quantity variation caused by parameters, taking account of the influence of fuel physical properties on dynamic injection characteristics of the system, a bond graph model of common rail injector has been proposed based on bond graph methodology and the state equations of the system are obtained. Comparisons between calculated fuel injection quantities by the numerical model and experimental measurements at different rail pressures and injection pulse widths indicate that the developed model can reasonably predict the fuel injection quantity characteristic of the system. Fuel injection quantity variation characteristics caused by the parameters of common rail injector have been analyzed in entire operating conditions. The selected parameters are delivery chamber diameter, needle seat semi-angle, needle cone semi-angle, ball valve seat semi-angle, nozzle hole diameter, inlet orifice diameter and outlet orifice diameter. The variation rules of quantitative percentages are obtained by quantitative analysis upon fuel injection quantity variation influential factors. It is concluded that ball valve seat semi-angle, nozzle hole diameter, inlet orifice diameter and outlet orifice diameter have the most significant effect on fuel injection quantity variation, and the followed are delivery chamber diameter and needle seat semi-angle. In addition, needle cone semi-angle also results in the variation of fuel injection quantity, but the effect is insignificant.

Effect of injector parameters on the injection quantity of common rail injection system for diesel engines

In this paper, the bond graph model of common rail injector was proposed in consideration of the effects of variable liquid capacitance and fuel physical property on the injection characteristics of the injector. State equations were derived based on the model, which were numerically solved by programming in Matlab. Comparisons between the simulation results and the experimental data show that the numerical model can effectively predict the injection quantity of the system. Effect of variation of delivery chamber diameter, needle seat semi-angle, needle cone semi-angle, ball valve seat semi-angle, nozzle hole diameter, inlet orifice diameter and outlet orifice diameter on fuel injection quantity had been analyzed. The influence rules of various parameters on the fuel injection quantity had been established. The experiments were conducted using face centered central composite design. A second order polynomial response surface model had been developed for predicting fuel injection quantity, as a function of the independent variables. Analysis of variation was used to determine the significance interactions which primarily affect the fuel injection quantity. It had been concluded that six interaction factors including delivery chamber diameter with nozzle hole diameter, needle seat semi-angle with needle cone semi-angle, needle seat semi-angle with nozzle hole diameter, needle cone semi-angle with nozzle hole diameter, nozzle hole diameter with inlet orifice diameter, and nozzle hole diameter with outlet orifice diameter have significant effect on the fuel injection quantity of the system.

함정용 디젤엔진의 노즐 직경 변화가 매연 발생에 미치는 영향

Legislative and regulatory actions regarding the exhaust gas from ships are being strengthened by both international organizations and national governments, to protect human health and the environment. Exhaust gas traps are excluded from exhaust gas regulation applications, but, recently, the United States, Britain, and other developed countries have examined a variety of ways to improve the system, including the introduction of electric propulsion systems to prevent air pollution generated by naval ships. This study investigates a large number of smoke problems of naval diesel engines to verify the effect of improving the nozzle characteristics. An exhaust gas emission measurement method to determine the quality of pollutant exhaust gas generated during low-load operation is proposed through the research methodology of the smoke problem. It was confirmed that the emissions value is improved by decreasing the nozzle hole diameter and increasing the injection pressure. At the same time, the flow rate decrease equation and setting up a test memo based on the nozzle diameter confirmed that the fuel consumption, to which the nozzle diameter in the flow path is related, is reduced.