Fuel Injection Nozzle Research Articles

On-machine evaluation of micro-EDM process signature in radio frequency (RF) domain: A step towards cost-effective data collection in a multiphysical process

In the growing age of digitization, there is a need for cost-effective data collection techniques to enable manufacturing data collection of production processes in small and medium scale enterprises (SMEs). This goes further where electrophysical processes, such as micro electrical discharge machining (micro-EDM) are employed in high-end micro-components such as fuel injection nozzles and precision components for automotive and aerospace sectors. There have been several efforts to get process information using electrical and acoustic monitoring, AI-based and multiphysics models, and fundamental physics experiments. All aforementioned techniques have contributed to improving understanding of the discharge behaviour in micro-EDM processes. However, they are all expensive and invasive in nature, thereby limiting their application for SMEs in enabling digitalisation of process-chain involving micro-EDM process.To address this gap, this paper investigates micro-EDM process signature in radio frequency (RF) domain and hence RF-based strategy is proposed as a low-cost and non-invasive process monitoring technique. Research is conducted to investigate the radiation sources and potential influencing factors during the EDM process. First, the RF mechanism in EDM is examined by analysing the monitored RF signals across different discharge stages of various pulse waveforms. From this analysis, the corresponding equivalent RF radiation models are established. Second, through an experimental design, the impact of different machining parameters, dielectric fluids, discharge states, monitoring equipment, and workpiece materials on RF signals are explored in both the time and frequency domains. The results indicate that only parameters related to breakdown voltage and gap current affect RF intensity, however, machining parameters show to be not significant on the radiation spectrum. The influence of dielectrics and workpiece materials on radiation behaviour is primarily associated with their corresponding equivalent resistance. Notable differences in both discharge pulses and antenna devices in monitoring RF signals are observed. Additionally, the monitorability of RF strategy is also evaluated under two application scenarios. By investigating the RF signals in EDM, it is expected to provide a non-invasive, interference-free, and low-cost method for discharge state monitoring.

The influence of the design features of the fuel injector atomizer on the process of diesel fuel injection

Abstract. Problem. Increasing the demands for the technical and economic characteristics and the resource of modern augmented diesel engines requires finding ways and approaches to improve their design and systems, in particular, their fuel supply system. Changing the design parameters of the fuel injector atomizer allows to influence the conditions of fuel injection, its atomization in the combustion chamber, and the efficiency of the engine. The number and mutual arrangement of the nozzle holes of the fuel injector atomizer and their diameter are chosen by manufacturers based on the design features of the engine, in particular, the configuration of the combustion chamber and the conditions for filling the cylinder with fresh air. Goal. The purpose of the work was to carry out comparative numerical modelling to assess the influence of the number and diameter of the nozzle holes of the fuel injector atomizer on the diesel fuel injection process. Methodology. The problem is considered in a three-dimensional non-stationary setting. For numerical modelling, the geometry of the flow part of the fuel injector atomizer was formed, taking into account its design features (standard and modernized versions). The standard version has 7 nozzle holes with a diameter of 0.25 mm (evenly arranged relative to the axis of the atomizer, and the modernized version has 4 holes with a diameter of 0.3 mm in the standard place, evenly arranged relative to the axis of the atomizer and, additionally, 4 holes with a diameter of 0.2 mm from above (in the area of the closing cone) evenly arranged relative to the axis of the atomizer, but with a rotation around the axis of the atomizer by 45 degrees relative to the lower holes. To describe the process of the diesel fuel flow in the flow part of the fuel injector atomizer, the k - ε turbulence model is used, and to describe the process of phase transition from a liquid state to a vapour state – a mixture model is used. Results. The obtained results showed that the use of two rows of nozzle holes of different diameters for the atomizer of the fuel injector of the transport diesel engine allows to effectively organize the fuel injection process. For the atomizer nozzle of the modernized design, the volumetric fuel consumption is 30% for the upper holes and 70% for the lower ones. Originality. The scientific novelty of the work lies in determining the influence of the number and diameter of the nozzle holes of the fuel injector nozzle on the conditions of diesel fuel injection, taking into account cavitation effects. Practical value. The total area of the nozzle holes in the modernized version was increased by 20%, which makes it possible to increase the cycle supply of diesel fuel. It is especially important when using new types of fuel with a lower paraffin content and, accordingly, lower caloric content

Diesel Fuel Injector Nozzle Reclamation

Diesel engines are integral to various industries due to their efficiency and durability. A key component of these engines is the fuel injector nozzle, which can degrade over time due to contaminants, carbon deposits, and mechanical wear. This paper examines the reclamation process for diesel fuel injector nozzles, highlighting its benefits, challenges, and the validation of reclaimed nozzles. Reclamation offers cost savings, environmental benefits, and extended component life, but requires stringent quality control and adaptation to technological advances. The paper underscores the importance of meticulous reclamation procedures and robust validation methods, such as dyno and on-road testing, to ensure the performance of reclaimed nozzles meets or exceeds original specifications. As diesel technology evolves, the reclamation industry must continuously adapt to maintain its relevance and efficacy.

Primary breakup of a jet coupled with vortex-induced string cavitation in a fuel injector nozzle

Fuel jet primary breakup strongly depends on the in-nozzle cavitation phenomena found in the high-pressure fuel injector nozzle. Nevertheless, limited attention has been paid to the mechanism of fuel jet primary breakup induced by in-nozzle vortex-induced string-type cavitation. This study involves simulations of in-nozzle string cavitating flow and simultaneously near-nozzle jet primary breakup process using large eddy simulation and volume of fluid, aiming at revealing the effects of string cavitation on jet primary breakup. The numerical results are in good agreement with experimental data in terms of string cavitation intensity, interfacial topology of jet, and spray spreading angle. The numerical investigations indicate that the external surface of the jet experiences Kelvin–Helmholtz instabilities, which results in the development of circumferential and axial surface waves at the fuel film surface. Subsequently, the fuel film surface undergoes progressive wrinkling, resulting in its breakup into multiple ligaments and large droplets. On the internal side of the jet, back-suction of air caused by negative pressure and its interaction with cavitation vapor at the core of the jet lead to the collapse of vapor bubbles. The resulting pressure waves and micro-jets facilitate the detachment of liquid sheets from the internal surface of the jet. Analysis of the enstrophy transport equation indicates that the driving mechanism behind string cavitation jet breakup further downstream is the baroclinic torque term, which is responsible for the generation of a cascade of smaller vortical structures. This effect dominates over vortex stretching and dilatation terms.

Performance enhancement of diesel engine using Karanja oil methyl ester as a fuel blend with diesel by variable injector nozzle hole

Diesel engines may run on biodiesel, a sustainable fuel that can be made from a variety of feedstocks using various alcohols and catalysts. The type of alcohol has a direct impact on the biodiesel’s fuel qualities. Variations in fuel qualities can lead to variations in diesel engine performance, combustion, and injection characteristics. Using blends of 10%, 20%, 30%, and 40% with Karanja oil and regular diesel fuel separately, experimental tests were conducted to assess the performance and emissions of a direct injection, water-cooled Kirloskar diesel engine at 1500 rpm with variable load. The 3-hole and 5-hole fuel injectors are the subjects of this investigation. Because Karanja methyl esters (KME) have a lower calorific value than diesel, their value increases with the proportion of KME in the mix. For a 20% blend, this means that brake-specific fuel consumption increases. As the amount of KME in the gasoline increases, the brake thermal efficiency falls. At a 20% mix, Brake thermal efficiency is almost identical to diesel fuel. For all blends, CO and HC emissions rise with load and fall with the fraction of KME in the mix. For every combination of KME, the density of smoke rises as the load increases. Smoke density falls as the fraction of mixes containing KME rises. It has been observed that when nozzle holes are increased from three to five, brake thermal efficiency rises with load. When comparing a 5-hole to a 3-hole with load, the Brake-specific fuel consumption (BSFC) will fall. Nozzles have an influence on emissions in that as nozzle holes grow, so do CO, HC, and smoke opacity. According to the findings, a 20% KME blend for a 5-hole fuel injector nozzle is a good substitute for diesel.

Visual coating inspection framework via self-labeling and multi-stage deep learning strategies

AbstractAn instantaneous and precise coating inspection method is imperative to mitigate the risk of flaws, defects, and discrepancies on coated surfaces. While many studies have demonstrated the effectiveness of automated visual inspection (AVI) approaches enhanced by computer vision and deep learning, critical challenges exist for practical applications in the manufacturing domain. Computer vision has proven to be inflexible, demanding sophisticated algorithms for diverse feature extraction. In deep learning, supervised approaches are constrained by the need for annotated datasets, whereas unsupervised methods often result in lower performance. Addressing these challenges, this paper proposes a novel deep learning-based automated visual inspection (AVI) framework designed to minimize the necessity for extensive feature engineering, programming, and manual data annotation in classifying fuel injection nozzles and discerning their coating interfaces from scratch. This proposed framework comprises six integral components: It begins by distinguishing between coated and uncoated nozzles through gray level co-occurrence matrix (GLCM)-based texture analysis and autoencoder (AE)-based classification. This is followed by cropping surface images from uncoated nozzles, and then building an AE model to estimate the coating interface locations on coated nozzles. The next step involves generating autonomously annotated datasets derived from these estimated coating interface locations. Subsequently, a convolutional neural network (CNN)-based detection model is trained to accurately localize the coating interface locations. The final component focuses on enhancing model performance and trustworthiness. This framework demonstrated over 95% accuracy in pinpointing the coating interfaces within the error range of ± 6 pixels and processed at a rate of 7.18 images per second. Additionally, explainable artificial intelligence (XAI) techniques such as t-distributed stochastic neighbor embedding (t-SNE) and the integrated gradient substantiated the reliability of the models.

Критическая толщина упрочняющего покрытия на рабочих поверхностях деталей распылителя форсунки

Motor vehicles and tractors operate in conditions of high dustiness. The main reason for the short service life of precision parts of fuel equipment (FI) is the abrasive wear of working surfaces. The innovative CVD method of obtaining coatings by thermal decomposition of chromium hexacarbonyl with subsequent deposition of chromium carbides significantly increases the wear and corrosion resistance of the injector nozzle parts of diesel engines. To increase the service life of the sprayer, the authors propose to apply a hardening coating to both working surfaces of the parts - the needle (steel R6M5) and the inner surface of the housing (steel 12KH2N4А). In order to minimize costs in the manufacture of new precision parts, the authors determined the critical (minimum) coating thickness, ensuring its load-bearing capacity. They also obtained analytical relationships between the minimum required coating thickness depending on its microhardness and the size of quartz and corundum particles, as well as regression equations and response function graphs. It has been established that in order to ensure the bearing capacity of the hardening coating on the fuel injector nozzle parts of the diesel engine, its critical thickness a should be not less than 3 microns at a microhardness of 18.9 GP.

INVESTIGATION OF THE EFFECTS OF VORTEX-INDUCED STRING CAVITATION ON FLOW AND SPRAY CHARACTERISTICS WITHIN DIESEL FUEL INJECTION NOZZLES

The diesel fuel injection system relies heavily on the precise operation of the fuel injection nozzle, universally recognized as its foundational component. A key factor significantly affecting both flow capacity and injection performance is the internal flow characteristics of the nozzle. This study investigates the vortex-induced string cavitation within fuel injector nozzles by incorporating high-speed imaging, particle image velocimetry techniques, and numerical simulations. The results demonstrate that an increase in injection pressure precipitates an escalation in string cavitation intensity, thus reducing the effective flow area and compromising internal flow capacity. Importantly, our study confirms that, despite its intensified occurrence under higher pressure, string cavitation does not cause significant erosion damage. Instead, it plays a pivotal role in promoting fuel atomization by injecting it into a rotational state, facilitated by the cyclonic action within the nozzle. Furthermore, our observations reveal a notable distinction between needle-hole string cavitation and hole-hole string cavitation. Specifically, needle-hole string cavitation produces more extensive spray angles compared to hole-hole string cavitation. However, it is crucial to note that the former exhibits reduced uniformity in the distribution of velocity fields and a weakening of the jet atomization effect. In conclusion, this comprehensive study provides valuable insights into the intricate mechanisms of string cavitation. Through an exhaustive exploration of flow characteristics, erosion effects, and atomization processes, our work significantly contributes to the field of fuel injection system engineering.

Comparison of the Flame Dynamics of a Liquid-Fueled Swirl-Stabilized Combustor for Different Degrees of Fuel-Air Premixing

Abstract This study investigates the flame dynamics of lean premixed kerosene combustion for two different degrees of fuel–air premixing using a swirl stabilized burner with an axially movable twin fluid fuel injection nozzle. Thermal power, equivalence ratio, and atomizing air mass flow are varied systematically for both nozzle positions investigated. Measurements of the droplet size distribution at the nozzle exit are provided for all operation points. NOx emission measurements and OH*-chemiluminescence flame images show that stationary combustion characteristics significantly change with the nozzle position. Flame Transfer Functions (FTFs) are presented and interpreted for all operation points. The FTFs for the two configurations differ most in the low frequency range where the influence of the droplet dynamics is expected to be highest. For both configurations, a change in thermal power does not affect droplet size, flame shape, NOx emissions, and FTF. The observed trends in response to changes in equivalence ratio and atomizing air mass flow are opposite for both configurations. NOx emissions and flame shape are independent of the atomization air mass flow in the highly premixed configuration but not in the partially premixed configuration. In contrast to this, the FTF is affected by changes of the atomization air mass flow in both configurations, but again the trends are opposite. The observed trends for the highly premixed configuration are modeled and reproduced by a change in the phase relation between the equivalence ratio fluctuations and other instability driving mechanisms.

Investigation of nozzle geometry and wall roughness effects on diesel injector flow

The flow and design of fuel injector nozzles have a considerable influence on the spray and combustion characteristics of a diesel engine. In-cylinder combustion, atomization, and primary breakdown are all highly influenced by the cavitation and turbulence in the fuel injector nozzle. In this paper, the effect of the nozzle geometry parameters, wall roughness parameters, and pressure difference on the swirl number, mass flow rate, turbulent kinetic energy, and vapor volume fraction is explored. U-type nozzle hole geometry, a well-known benchmark for the injector nozzle flow, is used to evaluate mesh independence and model validation. Large-eddy simulations are performed to provide a precise presentation of the flow structures and turbulent eddies inside the nozzle. Multiphase flow is studied using the mixture model, whereas cavitation is studied using the Schnerr–Sauer model based on the Rayleigh–Plesset equation. We find that the wall roughness parameters have an exciting impact on the discharge coefficient, swirl number, and vapor volume fraction. Due to the non-monotonic dependence of nozzle flow characteristics on the pressure difference and the wall roughness parameters, we can always find such values of these input parameters that render optimal nozzle flow characteristics. In this way, these parameters provide good control of spray formation and consequently on the quality and rate of combustion in the diesel engine.

Measurement of micropore by resonant probe with microsphere

A micro–nano coordinate measuring machine (CMM) is an instrument for high-precision measurement of micro-precision parts. The top of its probe is a microsphere with a diameter of tens to hundreds of micrometres. When the probe microsphere touches the part for measurement, its accuracy is affected by the surface morphology of the microsphere. A tuning fork resonant probe used for micro–nano CMMs is used to measure the contour of the micropore in automotive fuel injection nozzles in this study. Combined with the self-made optical fiber microsphere cross-sectional circle parameters at the top of the tuning fork probe, precise measurement of micropore diameter and roundness is achieved. During the experiment, the microsphere and micropore were measured by two independent systems, and thus, the error caused by the initial measurement angle of the microsphere and micropore is evaluated. The experimental results indicate that the measured micropore diameter is 194.542 µm and the roundness is 2.551 µm. The error caused by the initial measurement angle evaluated by the cubic Hermitian interpolation method can be ignored relative to the measurement results. The micropore structure parameters are precisely measured by the resonant probe combined with the morphology information of its top microsphere in this study, providing a research method for improving the measurement accuracy of micro–nano CMMs by combining microsphere morphology features.

Effects of Nozzle Diameter and Holes Number on the Performance and Emissions of a Gasoline Direct Injection Engine

The goal of the current study is to estimate how a gasoline direct injection (GDI) engine's performance and emissions are affected by the fuel injector nozzle diameter and hole number of its injectors. A thermodynamic mathematical modelling has been created utilizing a software program written in the MATLAB language to simulate the two-zone combustion process of a four-stroke direct injection engine running on gasoline at (Rotation Engine Speed 3000 revolution per minute (rpm), 40 MPa injection pressure, compression ratio 9.5, and spark timing 145°). The first law of thermodynamics, equation of energy, mass conserving, equation of state, and mass fraction burned were all used in the creation of the software program. The study was carried out at five different nozzle diameters (0.250, 0.350, 0.450, 0.550, and 0.650 mm) and nozzle hole numbers (4,6,8,10,12). The results show that the GDI engine's performance and emissions are significantly influenced by variations in nozzle hole diameter and number. It was shown that engine power, heat transfer, cylinder pressure, and temperature increased with increasing nozzle hole diameter and number of nozzle holes and the maximum value was seen with nozzle hole diameter 0.650 mm and (12) holes. The lowest value for the nozzle hole diameter and number of holes was found to be 0.250 mm and 4 nozzle holes, which resulted in the lowest emissions of carbon monoxide CO and nitrogen monoxide NO. The study was also conducted for different operating conditions (Rotation Engine speed of 1000, 2000, 3000, 4000, 5000 rpm ,35 MPa injection pressure , compression ratio of 11.5 , and spark timing of 140° ) and the same nozzle diameters and nozzle holes number mentioned previously to estimate the maximum values for temperature, pressure, power , heat transfer and emissions . The results of the second part of the study showed that the highest of maximum values of temperature, pressure, and emissions were at of 1000 rpm, a nozzle diameter of 0.650 mm, and (12) holes. The highest values for maximum power at 4000 rpm, a nozzle diameter of 0.650 mm and (12) holes, while the highest maximum values for heat transfer are at 5000 rpm, a diameter of 0.65mm and (12) holes.

Numerical study on the effects of viscous heating and random rough surface on cavitating flow in fuel injection nozzles

A transient numerical model was developed to investigate cavitating flow in fuel injection nozzles, incorporating the effects of viscous heating and latent heat of phase change. A three-dimensional Gaussian rough surface generated by Monte Carlo simulation was compared to a wall function correction-based roughness model to assess the impact of surface roughness on both flow and thermal fields. Results demonstrated that viscous heating increased fuel temperature significantly near the nozzle wall, whereas latent heat had minimal effect due to the diesel fuel's low thermal sensitivity. The random rough surface performed better than the wall function correction-based model in inducing local cavitation, reflecting sub-micron scale roughness, and revealing significant randomness in velocity, temperature, and cavitation fields. Roughness height and correlation length were found to be critical factors characterizing surface roughness, where an increase in roughness height and a decrease in correlation length predicted a rougher surface and enhanced effect of viscous heating. The ratio of these two parameters showed a clear linear relationship with temperature rise. Geometric and localized cavitation were observed, leading to temperature increases caused by cavity evolution and collapse. These insights are valuable for improving fuel atomization and combustion efficiency.

Study of an Indirect Injection Diesel Engine Using Pure Coconut Oil, Pure Tamanu Oil and B-20 as Fuel for Smart Microgrid Applications. Part I: Laboratory Testing

Smart Microgrid (SMG) is a hybrid system based on renewable energy which can use biofuel, taking advantage of local resources, as one of its energy sources. This study was conducted to determine the effect of using pure tamanu oil and pure coconut oil on engine performance, emissions, as well as their effects on particular components before and after endurance testing. The experiments were done using a diesel engine at speeds of 2200 rpm. In this study, engine performance and emission tests were done before and after the accelerated endurance tests, with loads of 800 W to 4000 W. The dimensions of the fuel injector nozzle needle and plunger pump were also measured. The fuel performance and emissions results showed slight differences between, before, and after endurance testing. The emissions tests also showed that the two biofuels, especially tamanu, are cleaner than B-20 and have better dimensional measurement results, compared to B-20. Therefore, these biofuels are feasible for replacing B-20, as shown in laboratory testing

Influences of injector geometry parameters on fuel injection characteristics and parameters of a diesel engine

Internal combustion engines (ICEs), especially diesel engines, continue to play a huge role in the development of the global economy. The research trends to improve combustion is still the main research direction in recent years with the help of 3D simulation tools. In this study, a 3D-model of a four-stroke, single-cylinder diesel engine was built using AVL Fire software to evaluate the influence of injector geometry parameters on engine characteristics. The results have shown that, with the injection pressure reaching 3000 (bar), and the turbocharger pressure maintained at 0.15 (MPa), the engine achieves the maximum power and the minimum brake fuel consumption when the angle between the axis of the nozzle hole and the axis of the fuel injection nozzle is 150 degrees. However, at this angle value, the soot emission value is the lowest but the nitrogen oxides (NOx) value is close to reaching the maximum. Hydrocarbon (HC) and carbon monoxide (CO) emissions are the lowest value at 155 degrees of the angle between the axis of the spray hole and the axis of the fuel injection nozzle. Besides, the study also evaluated the engine's parameters when changing the injector hole diameter. With an injection hole diameter of 0.24 (mm), the maximum engine power increased by 5.3%, and the brake-specific fuel consumption decreased by 7.2% compared to other values of injection hole diameter. However, the engine emissions are not the best values in this case.

Investigations of string cavitation and air back suction during injection duration in the scaled-up diesel fuel injection nozzle

The flow inside the diesel fuel injector nozzle is directly associated with the subsequent jet atomization and fuel–air mixture performance, and finally affects the combustion efficiency and emission. In this study, high-speed microscope imaging technology is applied to capture the complex multiphase flow and near-field spray during the process of fuel injection. Besides normal optical experiments for nozzle internal flow and spray, the submerged jet experiment for comparison is also carried out to investigate the phenomenon of air back suction. Combined with the simulation of a three-component multiphase model, the difference between air and cavitation vapor is analyzed. Results show that the submerged jet experiment will not change the internal flow field but can eliminate the influence of air. The shaded area in the hole obtained by the shadow method may be the sucked air or vapor generated by string-type cavitation phase change. Both can coexist in the hole and are closely related to the swirling intensity and the spray structure, respectively. When the needle lift is low, the internal flow field has larger swirling intensity resulting in a kind of hollow spray. The low-pressure region exists in the vortex core, nearly at the axis of the nozzle orifice. The ambient air will be sucked into the orifice to form an air column under the action of pressure difference, which is also easy to occur under low injection pressure. When the needle lift is high, the weak swirl intensity leads to hole-to-hole string cavitation which has weak cavitation intensity and obvious periodicity. At this time, the results of non-submerged and submerged jet experiments are basically the same. In addition, the cavitation bubble near the orifice outlet was observed, for the first time, to move upstream under the action of the pressure difference inside and outside the orifice in the submerged jet experiment. It can be predicted that in the non-submerged jet experiment, the ambient air will be sucked into the orifice to form an air column.

Модернизация CVD-установки для осаждения карбида хрома на внутренних поверхностях корпуса распылителя форсунки дизельных двигателей

Fuel injector nozzle parts tend to wear out due to abrasive particles of quartz and aluminum oxide penetrating into the fuel. The hardness of quartz abrasive particles exceeds the hardness of work surfaces in 1.4 times, and that of aluminum oxide – in 2.7 times. Strengthening one part of the fuel injector nozzle does not increase the service life sufficiently, so it is necessary to harden both parts of the precision pair. The CVD method is the most promising technology of wear-resistant coating deposition on steel machine parts. It produces carbide-chrome coating with microhardness up to 19 GPa (in vacuum conditions of 100 to 0.001 Pa) at temperatures above 200°C. The analysis of available devices and the review of patents of known solutions on the coating deposition from a steam phase have shown the impossibility of using these devices for restoration of the nozzle body. In this respect, the author developed a new reactor design and a scheme of the CVD unit for the coating deposition on the inner hard-to-reach surfaces of the nozzle body. The developed CVD unit takes into account the factors affecting chromium carbide deposition: thermodynamic conditions, reagent feed, deposition duration, unit parameters, adhesion and coating properties. The CVD unit upgrade results in making chromium carbide coating on the inner surfaces of the nozzle sprayer body, achieving thermodynamic equilibrium of chemical reaction of chromium hexacarbonyl decomposition at temperatures below 200°C (below the low tempering level of 18Х2Н4ВА, 12Х2Н4А and 40ХН2МА steel), and ensuring a controlled supply of a reaction medium to hard-to-reach areas, where refractory metal coatings are formed.

The comparative study of the influence of the parameters of the technological process of abrasive flow machining of the nozzle holes of the fuel injectors on the performance of the injection system

Improving the performance of automobiles is achieved by ensuring the optimal spraying characteristics of the mixture in the combustion chamber, which is achieved by changing the geometric parameters of the fuel flow of the fuel fluid through the nozzle. To obtain good energy performance of thermal engines in order to reduce pollution, it is used as processing operation (finishing and rounding) of the entrance to the fuel injector nozzle hole, erosion processing. Hydroerosion processing is carried out by removing the material to the erosive particles that are suspended in a working fluid, as a carrier. From the analysis of this process it follows that the reduction of cavitation, the rounding of the nozzle inlet can reduce the wear caused by the diesel flow when the injection system is in operation and implicitly the reduction of the impact of pollution on the environment.

Configuration effects of liquid fuel flameless combustion characteristics in a forward flow laboratory-scale furnace

ABSTRACT This paper presents the experimental results of a cylindrical combustor under flameless combustion with liquid fuel (LF) for three different configurations. The three flow field configurations constituted varying combinations of tangential air inlet ports and a central atomizing fuel injection nozzle to examine their effects on the FC characteristics of LF. They include optimal configuration (case 1) and two other configurations (case 2 and 3). The results for the three configurations are compared based on temperature distribution visual observation, and emissions. The combustor operated with ethanol in the range of thermal inputs of 21 to 11.3 kW with constant air (5.66 g/s) at ambient conditions. Low NOx and CO emissions, better temperature uniformity, and invisible flame have been observed in the flameless mode for the three configurations compared to the conventional flame. Whereas case 1 recorded lower NOx and CO emissions and higher temperature uniformity over the entire volume of the combustor as compared to the other two cases and referred to an optimal configuration for the present combustor.

Passive cavitation imaging in fuel injector nozzles

Modern fuel injection systems operate at high pressures and flow velocities. Injectors can be pressurized in excess of 10 MPa, resulting in fuel velocities on the order of hundreds of meters/second in the mm and sub-mm internal confines of a fuel injector. Subsequent ejection velocities at the nozzle yield characteristic atomization droplet size distributions and spread angles. Studies have shown or inferred the presence of cavitation in such fuel injectors, typically beneficially decreasing ejection droplet sizes while increasing the spray spreading angle. While beneficial for fuel atomization, it is known that bubble collapse near a solid surface produces a strong jet which impinges on the surface and causes erosion. In this study, Fourier based image reconstruction is used to perform Passive Cavitation Imaging (PCI) in laboratory nozzles to detect, characterize, and most importantly localize inertial cavitation. [Work funded by DOE.]