Nozzle Hole Diameter Research Articles

Probing into the Effects of Fuel Injection Pressure and Nozzle Hole Diameter on Spray Characteristics under Ultra-high Injection Pressures Using Advanced Breakup Model

In this article, non-evaporating and non-reacting diesel spray is modeled under ultra-high injection pressure using an Eulerian-Lagrangian scheme. This is accomplished in order to probe into the effects of injection pressure, nozzle diameter, and ambient density on spray characteristics. An advanced hybrid breakup model that takes into consideration the transient processes during spray injection has been added to the open source code OpenFOAM. Reynolds-Average Navier-Stokes (RANS) equations are solved using standard turbulence model and fuel droplet is tracked by a Lagrangian scheme. Published experimental data have been used for validation of spray characteristics at 15 kg/m3 ambient density and injection pressures of 100, 200 and 300MPa. Also, three nozzle diameters of 0.08, 0.12 and 0.16mm have been implemented for investigating the effect of this parameter on spray formation. Computed spray shape, jet penetration, spray volume, equivalent ratio along the injector axis and Sauter Mean Diameter (SMD) illustrate good agreement with experimental data of single hole nozzle and symmetric spray. The effects of fuel injection pressure, nozzle hole diameter and ambient density on main spray parameters are presented. It is concluded that numerical model presented here is quite suitable for accurately predicting diesel spray shapes under ultra-high injection pressures.

Investigation on the fuel injection quantity fluctuation of a common-rail fuel injection system using response surface methodology

Variations in the parameters affect the injection characteristics of a common-rail injection system and leads to fluctuation in the fuel injection quantity. This paper is aimed at combining the numerical modelling and design of experiments to investigate the significant effects of the interactions between the common-rail injector parameters on the fluctuation in the fuel injection quantity using response surface methodology. A numerical model of a common-rail injector was developed. The model was validated by comparing simulation results with experimental measurements, which showed that it can accurately predict the fuel injection quantity of the system. The design of experiments was performed using a two-level five-factor D-optimal design. The factors studied were the pre-tension of the control valve spring, the diameter of the outlet orifice, the diameter of the inlet orifice, the needle lift and the diameter of the nozzle holes. A quadratic response surface model was suggested by means of partial least-squares regression analysis. The distribution of the standardized residuals, the relation between the predicted fluctuation and the observed fluctuation in the fuel injection quantity, the coefficient R2 of determination and the adjusted coefficient [Formula: see text] of determination for the response surface model were analysed, which demonstrated the significance of the model. Analysis of the F value and the p value for the model terms at the 95% confidence level revealed that the interactions between the control valve spring pre-tension and the nozzle hole diameter, between the outlet orifice diameter and the nozzle hole diameter, between the inlet orifice diameter and the nozzle hole diameter and between the needle lift and the nozzle hole diameter had significant effects on the fluctuation in the fuel injection quantity of the system. Furthermore, the significant effects of the interactions between these parameters were analysed in detail.

연속 살균기의 온도제어 및 최적설계에 관한 연구

In this paper, we analyzed the problems of a batch-type sterilizer and design a continuous sterilizer to control the temperature deviation. The temperature deviation is analyzed with respect to design parameters such as a nozzle diameter, hole diameter, and nozzle length. The significant temperature parameters are optimized using the response surface methodology. An experimental apparatus is developed using the optimized design parameters. Using a field test, we show that the target temperature is obtained in about 7.3 minutes and the temperature deviation is improved about 0.84 . The optimized parameters from the test are ℃

Characteristics of the internal flow and the near-field spray of a single-hole injector and a multi-hole injector for diesel engines

The geometric structure of a diesel fuel injector plays a significant role in the injected spray behaviours. Furthermore, the characteristics of diesel fuel spray are well known to have a crucial impact on the combustion process and the resulting engine performance. A single-hole diesel injector is usually applied in fundamental internal flow, spray and combustion research. On the contrary, under most realistic operating conditions, an axisymmetric multi-hole injector is used to couple with the combustion chamber. In the present paper, a detailed experimental investigation of the diesel fuel spray emerging from a single-hole nozzle and a multi-hole nozzle and a computational study of the internal flow inside these two kinds of configuration are reported. Globally, the analysis mainly focused on the different injection processes (the injection rate) and the spray structures of the single-hole nozzle and the multi-hole nozzle, keeping the same sac configuration, the same nozzle hole diameter of 0.1 mm and the same hole length of 0.8 mm for an injection quantity of 2 mm3 per hole. High-speed images of the spray development were freeze captured by Mie scattering at 10,000 frames/s under the conditions where the rail pressure varies from 80 to 180 MPa, the ambient pressure is 1.5 MPa, the room temperature T = 298 K and there is an air environment. Image-processing algorithms were used to determine the fuel spray characteristics. The experimental results revealed that the spray of a multi-hole nozzle with 10 holes had a longer injection duration, a lower injection rate, a shorter spray tip penetration, a wider spray angle and a wider spray cone angle than those of a single-hole nozzle. The spray behaviours of the multi-hole nozzle were more sensitive to variation in the pressure than those of the single-hole nozzle. Moreover, aiming to correlate the observed spray properties to the internal flow phenomenon, computational fluid dynamics simulations were also carried out under the baseline conditions. The more complicated internal flow inside the multi-hole nozzle provided added insight into the different spray characteristics for these two nozzles.

English

In the present study an experimental work had been carried out to analyze the combustion parameters of B20 neem blend by varying injection pressure and nozzle hole diameter. The engine tests are conducted on kirloskar 4- stroke single cylinder 1500 rpm water cooled direct injection diesel engine with eddy current dynamometer with standard injection timing 23˚bTDC was maintained constant throughout the experiment. 3 different injection pressures such as 210 bar, 230 bar, 250 bar and 3 different nozzles such as (3×0.28mm), (4×0.23mm), (5×0.20mm) varied to analyze the combustion parameters. From the test results, it could be observed that among 3 different nozzles (3×0.28mm) nozzle gives higher Peak pressure rise as compared to 4 hole nozzle and 5 hole nozzle.

Ultrafast X-ray study of multi-hole GDI injector sprays: Effects of nozzle hole length and number on initial spray formation

Nozzle hole design factors, such as length, diameter, position and number of nozzle holes, significantly alter the near-field jet flow and following spray formation of fuel injection nozzles. This study investigates the effects of various nozzle hole design factors on near-field jet flow and spray formation of the multi-hole injectors for gasoline direct-injection (GDI) engines. The novelty of this study lies in intensive analysis in the near-field jet breakup, dynamics and droplet formation process that have rarely been characterized from previous studies by exploiting the potentials of synchrotron X-ray for near-field spray analysis. Among several nozzle hole design factors, the effects of the length and number of nozzle holes are investigated in the current paper as the first part. Four prototype injection nozzles, which have different lengths and numbers of nozzle holes with a substantially low needle lift of 35μm, were used for this fundamental study. Single- and multi-exposed X-ray phase-contrast images were used to characterize the jet breakup, dynamics and droplet formation process from the nozzle exit to 30mm downstream. The emerging jet flows from the multi-hole GDI injectors were highly turbulent and perturbed immediately from the nozzle exit. The decrease in nozzle hole length increased the axial and radial flow velocity of the emerging jet flow with an increased void fraction inside the nozzle hole at the nozzle exit. It promoted the jet breakup with formation of smaller and more circular liquid ligaments/droplets in the near-field when the nozzle hole length decreased, which accompanied the higher velocity decrease rate and turbulence strength along the spray axis. On the other hand, the increase in the number of nozzle holes decreased the axial and radial flow velocity of the emerging jet flow. It led to a slower breakup of the jet flow with a lower velocity decrease rate along the spray axis at larger number of nozzle holes.

증발 조건에서 초고압 분사와 노즐 홀 직경이 디젤 유량 및 분무 특성에 미치는 영향에 대한 연구

Experimental study was conducted to investigate the effects of ultra-high injection pressure and nozzle hole diameter on diesel flow and spray characteristics. Electronically controlled ultra-high pressure fuel injection system was made to supply the fuel of ultra-high pressure consistently. Three injection pressures, 80, 160, and 250MPa were applied. Four type of injec- tors with identical eight nozzle holes were used. The four injectors have nozzle hole diameters of 115, 105, 95, and 85μm respectively. Injection quantity and rate were measured to investigate flow characteristics according to injection pressures and nozzle hole diameters. Mie-scattering and shadowgraph were performed to visualize liquid and vapor phases of diesel spray in a constant volume combustion chamber (CVCC). Ambient conditions of high pressure and high temperature in a diesel engine were simulated by using CVCC.

G0700504 ディーゼル噴霧特性に及ぼす噴孔径の影響

G0700504 ディーゼル噴霧特性に及ぼす噴孔径の影響

Effect of nozzle hole size coupling with exhaust gas re-circulation on the engine emission perfomance based on KH-ACT spray model

To research an effective measure of reducing the Soot and NOx in engine at the same time, different nozzle hole diameters coupled with exhaust gas recirculation (EGR) were adopted in this study based on KH-ACT spray breakup model, which takes the aerodynamic-induced ,cavitation-induced and turbulence-induced breakup into account. The SAGE detailed chemistry combustion and the new atomization model used in the simulation have been verified with the experiment data from a YN4100QBZL engine. Different diesel nozzles was adopted in the study combined with different EGR rates ranging from 0% to 40%. The simulation results show that the NOx emission could be reduced effectively for both small(0.1mm) and large(0.15mm) diesel nozzle when increasing EGR ratio. The soot emission increases for the small nozzle hole size as the EGR increasing. However, when it comes to the large diesel nozzle, the emission increases slightly first and decrease quickly when the EGR rate above 20%.

Study of behavior characteristics of diesel fuel spray according to breakup models

The atomization of the injection fuel in the diesel engine directly affects on the combustion process of engine, and as a result, it is the main factor that determines the operating performance of the engine. In this study, the breakup process of the droplets by the atomization of the injected was investigated, using the breakup models (Reitz&Diwakar, CAB, ETAB and TAB) included in the commercial numerical analysis program. In order to select the optimum model for the droplet breakup interpretation, the results of spray tip penetration, Sauter mean diameter (SMD) and momentum length obtained as each breakup model were compared with the experimental data. In the case of changing of the spray tip penetration as the research results, TAB model was measured the shorter compared to the experimental measurements, and other models showed the similarity with the experimental value. In the case of SMD analysis, the use of Reitz&Diwakar model showed the best results. In addition, the frequency of breakup which is the microscopic spray behavior characteristics considering the impact of the coefficient of contraction in the nozzle was investigated in order to determine the diameter of initial particle in the fuel injection necessary to the numerical analysis. As a result, it was found that there is suitable initial droplet diameter in numerical analysis, in the case of nozzle-hole diameter 0.12mm of this study, it was the most appropriate that the diameter of the initial particle for the numerical analysis is about 0.06mm.

Experimental research on flash boiling spray of dimethyl ether

The high-speed digital imaging technique is applied to observe the developing process of flash boiling spray of dimethyl ether at low ambient pressure, and the effects of nozzle opening pressure and nozzle hole diameter on the spray shape, spray tip penetration and spray angle during the injection are investigated. The experimental results show that the time when the vortex ring structure of flash boiling spray forms and its developing process are determined by the combined action of the bubble growth and breakup in the spray and the air drag on the leading end of spray; with the enhancement of nozzle opening pressure, the spray tip penetration increases and the spray angle decreases. The influence of nozzle hole diameter on the spray tip penetration is relatively complicated, the spray tip penetration is longer with a smaller nozzle hole diameter at the early stage of injection, while the situation is just opposite at the later stage of injection. This paper establishes that the variation of spray angle is consistent with that of nozzle hole diameter.

English

In this study, the effects of fuel injection discharge curve and injection pressure onpower upgrade of heavy-duty diesel engine by simulation of combustion process in AVL-Fire software are discussed simultaneously. Hence, the fuel injection discharge curve is changed from semi-triangular to rectangular which is usual in common rail fuel injection system. Injection pressure with respect to amount of injected fuel and nozzle hole diameter are changed. Injection pressure is calculated by an experimental equation which is developed for heavy duty diesel engines with common rail fuel injection system. Power upgrade for 1000 and 2000 bar injection pressures are discussed. For 1000 bar injection pressure with 188 mg injected fuel and 3 mm nozzle hole diameter, power is upgraded about 19% in comparison to original state which is semi-triangular discharge curve with 139 mg injected fuel and 3 mm nozzle hole diameter, with no special change in cylinder pressure. On the other hand, both the NOX and the Soot emissions decreased about 30 and 6%, respectively. Compared with the original state, in the case of 2000 bar injection pressure, with injected fuel and nozzle diameter, 196 mg and 2.6 mm respectively, the power is upgraded about 22%, whereas cylinder pressure has been fixed, and the NOX and the Soot emissions are decreased to 36 and 20%, respectively.   Key words: Computational fluid dynamics (CFD) simulation, heavy-duty (HD) diesel engine, upgrading power, injection pressure, fuel injection discharge curve, combustion process.

Characterization of a Set of ECN Spray A Injectors: Nozzle to Nozzle Variations and Effect on Spray Characteristics

The Engine Combustion Network (ECN) is becoming a leading group concerning the experimental and computational analysis of Engine combustion. In order to establish a coherent database for model validation, all the institutions participating to the experimental effort carry out experiments at well-defined standard conditions (in particular at Spray A conditions: 22.8kg/m3, 900K, 0% and 15% O2) and with Diesel injectors having the same specifications. Due to the rising number of ECN participants and also to unavoidable damages, additional injectors are required. This raises the question of injector's characteristics reproducibility and of the appropriate method to introduce such new injectors in the ECN network. In order to investigate this issue, a set of 8 new injectors with identical nominal Spray A specification were purchased and 4 of them were characterized using ECN standard diagnostics. In particular, the measurements include the nozzle hole diameter, the rate of injection, the liquid and vapor penetrations, the auto-ignition delay and the lift-off length. Variations of ambient temperature, oxygen concentration and density have also been performed. In general the results show similar behavior to ECN standard injectors, confirming that this set of new injectors can be integrated into the pool of ECN injectors. However, discrepancies between spray characteristics were observed, although the injector specifications and the boundary conditions were sensibly the same. The sources of variations from injector to injector are analyzed in order to provide new information on the reproducibility of injectors characteristics, and improve the comparison methodology between experimental data and simulation.

Numerical Investigation of Aero Engine Afterburner Fuel Manifold

In this paper, Method of CFD is used to simulate afterburner fuel manifold for aero engine, and investigate the relationship between the boundary layer of nozzle hole and mass flow. At the same time the numerical simulation of permitted maximum and minimum of nozzle hole was carried out and mass flow for calculation was also compared with the design value. The calculation results show the effect of machining quality of nozzle holes on mass flow of afterburner fuel manifold, for which the diameter of nozzle hole is so small that the effects of machining precision and boundary layer thickness on mass flow is very large. Therefore the jet fuel must be machined according to tolerance level I so as to ensure that the mass flow meets the design requirements. Investigation of boundary layer of small hole shows that only the boundary layer factors are fully considered, the numerical calculation accuracy may be enhanced.

DME 커먼레일 시스템을 위한 인젝터 분사 유량 개선

In this study, injection flow rates and material of the solenoid sealing of the injectors were improved for the development of a di-methyl Ether(DME) common-rail system. To deliver the same amount of energy provided by injection pressure of diesel <TEX>$P_{inj}$</TEX> = 160 MPa, the DME injectors need to have larger diameter of nozzle hole and more No. of hole at low injection pressure of <TEX>$P_{inj}$</TEX> = 40~50 MPa. The simplified nozzle flow model, which takes account of nozzle geometry and injection condition, was employed in order to design the concept of a injector nozzle such as No. of hole, diameter of hole and diameter of needle seat, etc. Injection amount and rate were tested by diesel and DME test stand. As a result, the diameter of nozzle hole were enlarged by 0.25 mm. The diameter of the orifice in the high pressure line was increased by 1.0 mm to maintain hydraulic force in the nozzle. The material of the solenoid sealing was changed to HNBR, which was strong against the corrosive. Experimental results showed that the injection amount of the DME injector drastically increased by 191.9% comparison to that of diesel at <TEX>$P_{inj}$</TEX> = 40 MPa.

LARGE EDDY SIMULATION OF HIGH-VELOCITY FUEL SPRAYS: STUDYING MESH RESOLUTION AND BREAKUP MODEL EFFECTS FOR SPRAY A

Large eddy simulation (LES) of the nonreacting Spray A target conditions, as defined by the Engine Combustion Network, are carried out and compared to high-quality, experimental validation data. The investigated test case is characterized by a high injection pressure, small nozzle hole diameter, and inert ambient gas conditions at high-temperature and high-pressure. In the present study, implicit LES is used together with the Lagrangian particle tracking approach for the liquid phase to (i) investigate the effect of mesh resolution and (ii) study the influence of droplet breakup modeling on the local and global flow characteristics. Two breakup models are compared at four different mesh resolutions. The results are quantitatively analyzed with respect to integral spray quantities and validated against the experimental data. Qualitative characterization of the local velocities and mixture formation is presented. A good agreement of simulated and measured liquid/vapor penetration is achieved for both breakup models, given a sufficient mesh resolution. However, local differences in droplet diameter and vapor mass are observed between the breakup models in the nozzle vicinity. The overall mixture formation shows little dependency on the breakup modeling approach yet a strong dependency on the mesh resolution.

Optimization of diesel engine parameters using Taguchi method and design of evolution

The objective of this work is to optimize the control parameters of the direct injection (DI) single cylinder diesel engine with respect to NOx (Oxides of Nitrogen) and fuel emissions through experimental investigations and Taguchi method. A single cylinder 5.2 kW diesel engine was selected for this experiment. Five parameters such as clearance volume, valve opening pressure, nozzle-hole diameter, static injection timing and load torque were varied at four levels and the responses such as NOx emissions and fuel economy were recorded. The optimum values of the response variables could be predicted using S/N ratio and optimum combination of control parameters were specified. Results of confirmation tests showed good agreement with predicted results. Thus the relationship between the diesel engine operating parameters with NOx and b.s.f.c (brake specific fuel consumption) could be understood using Taguchi method of experimental design.

디젤 엔진의 인젝터 설계 변수가 노즐 코킹에 미치는 영향 분석

Recent common-rail injector of a diesel engine needs more smaller nozzle hole to meet the stringent emission regulation. But, small nozzle hole diameter can cause nozzle coking which is occurred due to the deposits of post-combustion products. Nozzle coking has a negative effect on the performance of fuel injector because it obstructs the fuel flow inside a nozzle hole. In this study DFSS (Design for six sigma) method was applied to find the effect of nozzle design parameter on nozzle coking. Total 9 injector samples were chosen and tested at diesel engine. The results show that nozzle hole diameter and K-factor have more effect on nozzle coking than A-mass and hole length. Large hole diameter and A-mass, small hole length and K-factor give more positive performance on nozzle coking in these experimental conditions. But, a performance about nozzle coking and exhaust gas emission shows the opposite tendency. Further study is needed to find the relation between nozzle coking and emission characteristic for the optimization of injector nozzle design.

An investigation of the effects of fuel injection pressure, ambient gas density and nozzle hole diameter on surrounding gas flow of a single diesel spray by the laser-induced fluorescence–particle image velocimetry technique

The characteristics of ambient gas motion induced by a single diesel spray were measured quantitatively by using a laser-induced fluorescence–particle image velocimetry technique under non-evaporating quiescent conditions. The effects of fuel injection pressure, ambient gas density and nozzle hole diameter on the ambient gas mass flow rate into the spray through the whole spray periphery (spray side periphery and tip periphery) were investigated quantitatively according to the gas flow velocity measurements. The results show that the captured gas mass flow rate through the spray tip periphery is prominent in the whole periphery and the proportion of the gas entrainment through the spray side periphery increases with spray development. The higher injection pressure significantly enhances the total gas mass flow rate through the whole periphery; however, the increase in the ratio of ambient gas and fuel mass flow rate becomes moderate gradually with the increase in the injection pressure. The higher ambient gas density results in a slight increase in ambient gas flow velocity along the spray side periphery and the tip periphery and a reduction of the spray volume; however, the ambient gas mass flow rate was apparently enhanced. The smaller nozzle hole diameter results in a significant decrease in the ambient gas mass flow rate and an increase in the ratio of the gas and fuel mass flow rate. Numerical simulation results provide more understanding of the spray-induced gas flow field and validate the measurement accuracy of the laser-induced fluorescence–particle image velocimetry results.

Characterization of spray and combustion processes of biodiesel fuel injected by diesel engine common rail system

The influence of injection pressure up to ultra-high value of 300MPa, nozzle hole diameters of 0.16 and 0.08mm and fuel properties such as boiling point, cetane number and oxygen content on spray, ignition and combustion characteristics of biodiesel fuel in diesel engine were investigated. Biodiesel from palm oil source (BDF) and for comparison the JIS #2 diesel fuel were utilized. The Mie-scattering technique was used for characterizing the evaporating spray formation processes while the OH chemiluminescence technique was used to determine the ignition and the lift-off length of the combusting flame. Furthermore, the two color pyrometry was applied to study the soot formation processes. The results obtained indicated that due to higher boiling point, the BDF produced longer liquid phase length as compared to diesel. It was observed that the ignition region was larger for the 0.16mm nozzle as compared to the 0.08mm. Due to the enhanced mixing processes, ignition delay decreased as the injection pressure increased from 100 to 300MPa respectively and also by reducing the nozzle hole diameter to 0.08mm. Higher cetane number and oxygen content of the BDF facilitated shorter ignition delay as compared to diesel. The percentage stoichiometry air entrained increased by decreasing the nozzle hole diameter. The BDF flame produced shorter lift-off length and lower percentage stoichiometry air. Under higher injection pressures and decreasing nozzle diameter, the BDF produced less soot as compared to diesel. The fuel oxygen content in the biodiesel fuel played a greater role in the soot formation processes.