Vapor Penetration Length Research Articles

Investigating the effect of fuel properties and environmental parameters on low-octane gasoline-like fuel spray combustion and emissions using machine learning-global sensitivity analysis method

The gasoline compression ignition mode is an advanced combustion mode that achieves high efficiency with low emissions. This study constructs a global sensitivity analysis (GSA) by coupling machine learning (ML) algorithms and conducts a comprehensive investigation into the statistical correlations between research octane number (RON), fuel sensitivity (S), three initial ambient parameters, and the spray combustion characteristics of gasoline-like fuels. Eighty sets of CFD numerical simulation data were used for training the machine learning model. Results show liquid length (LL) is most sensitive to changes in ambient pressure while ambient temperature significantly influences vapor penetration length (VPL). Regarding combustion behaviors, ignition delay (ID) and flame lift-off length (LOL) show the highest sensitivity to ambient temperature. The occurrence of distinct ignition points in the domain also advances from 1.75 ms to 0.42 ms as the ambient temperature rises from 1000K to 1200K. Additionally, the ambient temperature has higher-order interaction effects with ambient pressure on LOL. The production of NOx in the field is also more closely correlated with ambient temperature, with higher temperatures promoting its generation. Furthermore, ambient temperature exhibits a positive interaction effect with both ambient pressure and oxygen concentration on NOx emissions.

Physics-based reduced-order modeling of flash-boiling sprays in the context of internal combustion engines

Flash-boiling injection is one of the most effective ways to accomplish improved atomization compared to the high-pressure injection strategy. The tiny droplets formed via flash-boiling lead to fast fuel–air mixing and can subsequently improve combustion performance in engines. While most of the previous studies related to the topic focused on modeling flash-boiling sprays using three-dimensional (3D) computational fluid dynamics (CFD) techniques such as direct numerical simulations (DNS), large-eddy simulations (LES), and Reynolds-averaged Navier–Stokes (RANS) simulations, the present work introduces a reduced-order cross-sectionally averaged spray (CAS) model with significantly reduced computational cost. The proposed CAS model incorporates several physical submodels in flash-boiling sprays such as those for air entrainment, drag, superheated droplet evaporation, flash-boiling induced breakup, and aerodynamic breakup models. The CAS model is then applied to different fuels to investigate macroscopic spray characteristics such as liquid and vapor penetration lengths under flash-boiling conditions. It is found that the newly developed CAS model captures the trends in global flash-boiling spray characteristics reasonably well for different operating conditions and fuels. Moreover, the CAS model is shown to be faster by up to four orders of magnitude compared with simulations of 3D flash-boiling sprays. The novelty of the present work lies in providing a reduced-order flash-boiling spray model that offers cost-effective computational representations of complex phenomena. The proposed model can be very valuable for applications, such as experimental design, fuel screening, and creating digital twins, thus playing a crucial role in the advancement of research and development in the field of spray combustion.

Comparative Spray Atomization and Evaporation Characteristics of Dimethyl Ether and Mineral Diesel

Abstract Dimethyl ether is a new-generation alternative fuel to mitigate cold-start issues in compression ignition engines. It has a higher cetane number and can efficiently lead to superior atomization and evaporation characteristics. This computational study compares Dimethyl ether and baseline diesel sprays in a constant-volume spray chamber. This simulation study compares spray and evaporation characteristics en-hancement due to Dimethyl ether adaptation. Fuel properties greatly influence spray atomization and evaporation characteristics. This study is based on the Eu-lerian-Lagrangian approach adopted in the Reynolds-averaged Navier-Stokes framework. The liquid spray penetration obtained by simulations matched well with the experimental results of Dimethyl ether and baseline diesel. Spray model con-stants were tuned for diesel and Dimethyl ether separately, as the fuel properties of both test fuels are completely different. These tuned models were used to simulate Dimethyl ether and diesel sprays at fixed fuel injection timings and ambient condi-tions. Results showed a lower spray penetration length for Dimethyl ether than die-sel because of the flash boiling of Dimethyl ether. Smaller diameter droplets formed due to Dimethyl ether's lower viscosity, density, surface tension, and higher evapora-tion rate. The reduction in Sauter mean diameter was quite sharp after the start of injection for the Dimethyl ether. Diesel spray showed retarded atomization and evaporation compared to Dimethyl ether. The vapour penetration length of both fuels was almost the same; however, the vapor mass fraction was higher for Dime-thyl ether than baseline diesel. Dimethyl ether spray showed superior spray atomi-zation and improved evaporation of Dimethyl ether droplets.

Limitations of cetane number to predict transient combustion phenomena in high-pressure fuel sprays

Fundamental understanding of in-cylinder processes in diesel engines is important to screen emerging biofuels and advanced combustion modes that can reduce greenhouse gas emissions and regulated pollutants including soot. In this study, the role of fuel properties on spray development and combustion is investigated by systematically isolating chemical and thermophysical effects. Three different fuels are considered, two with similar chemical properties and two with similar thermophysical properties with one fuel common to both groups. Experiments are performed in a constant-pressure flow chamber designed to provide stable test conditions and facilitate acquisition of at least 150 injections in quick succession for each fuel under reacting high-pressure, high-temperature ambient conditions using a modified conventional diesel engine injector. High speed optical diagnostics including rainbow schlieren deflectometry, OH* chemiluminescence, and a two-color pyrometry system are employed to simultaneously image the transient spray and reacting jets. Image analysis is performed to determine liquid length, vapor penetration length, timing and location of first stage and main ignition events, lift-off location, total soot mass, and more. Results show that fuels with similar chemical properties or cetane number (CN) exhibit similar delay times for first stage and main ignition events as may be expected, but very different liquid length, first stage and main ignition locations, lift-off length, apparent turbulent flame speed, and soot formation. As such, the ability to characterize candidate biofuels with CN or other parameters derived from simple flame configurations is called into question. In this study, thermophysical properties controlling the liquid length are identified as the main contributing factor for the observed differences.

Modeling Spray C and Spray D with FGM within the framework of RANS and LES

In this study, two different diesel-like igniting sprays are investigated: Engine Combustion Network (ECN) Spray C and D. In particular, this study focuses on the respective performances of the RANS and LES models to predict a turbulent, igniting spray using the OpenFOAM platform. The breakup model, discretization schemes, and case setups, including the combustion model, are kept constant in order to mitigate any potential effect on the simulation apart from intrinsic differences due to turbulence modeling. A classic κ-ε model is applied for the RANS approach, while a dynamic structure model is used to solve the momentum equation in the LES approach. The κ-ε model constants are tuned to obtain a suitable prediction of inert experiments. Both approaches exhibit a reasonable agreement with the inert experiments regarding the global spray characteristics, the liquid length, and the vapor penetration. However, the transient local properties, including the spatial distribution of mixture fraction variance and the species distributions, are not identical. For reacting conditions, the Flamelet Generate Manifold (FGM) model is adopted in both the LES and RANS simulations, using several enthalpy levels as the fourth dimension in the tabulation to account for local heat loss. The results show good agreement between the two turbulence models, in terms of liquid length, vapor penetration, and lift-off length, while a short ignition delay is registered for both sprays and turbulence frameworks. Turbulence–chemistry interaction (TCI) is considered by applying a presumed probability density function (β-PDF) to the mixture fraction, and is found to play a key role in the reproduction of species distribution in the domain.

Impact of Multi-Component Surrogates on the Performances, Pollutants, and Exergy of IC Engines.

Even though there is a pressing interest in clean energy sources, compression ignition (CI) engines, also called diesel engines, will remain of great importance for transportation sectors as well as for power generation in stationary applications in the foreseeable future. In order to promote applications dealing with complex diesel alternative fuels by facilitating their integration in numerical simulation, this paper targets three objectives. First, generate novel diesel fuel surrogates with more than one component. Here, five surrogates are generated using an advanced chemistry solver and are compared against three mechanisms from the literature. Second, validate the suggested reaction mechanisms (RMs) with experimental data. For this purpose, an engine configuration, which features a reacting spray flow evolving in a direct-injection (DI), single-cylinder, and four-stroke motor, is used. The RNG k-Epsilon coupled to power-law combustion models is applied to describe the complex in-cylinder turbulent reacting flow, while the hybrid Eulerian-Lagrangian Kelvin Helmholtz-Rayleigh Taylor (KH-RT) spray model is employed to capture the spray breakup. Third, highlight the impact of these surrogate fuels on the combustion properties along with the exergy of the engine. The results include distribution of temperature, pressure, heat release rate (HRR), vapor penetration length, and exergy efficiency. The effect of the surrogates on pollutant formation (, , ) is also highlighted. The fifth surrogate showed 47% exergy efficiency. The fourth surrogate agreed well with the maximum experimental pressure, which equaled 85 Mpa. The first, second, and third surrogates registered 400, 316, and 276 g/kg fuel, respectively, of the total CO mass fraction at the outlet. These quantities were relatively higher compared to the fourth and fifth RMs.

Study of Spray Behaviors to Correlate with Engine Performance and Emissions of a Diesel Engine Using Canola-Based Biodiesel

The use of renewable biodiesel fuel in diesel engines can reduce the demand for depleting fossil fuels and reduce harmful emissions to the environment. In this research, an engine simulation is conducted using ANSYS Forte software, which allows for visualization of the spray inside the combustion chamber. The results show that biodiesel has higher liquid and vapor penetration lengths, higher droplet mass and diameter, and a longer breakup length. Molecular images of fuel molecules show that the temperature of biodiesel molecules is 141 °C lower than diesel molecules at 709 degree crank angle (°CA). These characteristics result in an extended evaporation time for biodiesel, consequently leading to poorer performance. Additionally, increased penetration length can lead to carbon deposits inside the combustion chamber. Therefore, such inefficiencies of biodiesel spray properties lead to lower combustive performance than diesel. In terms of performance, on average, biodiesel produces 16.9% lower power and 19.9% higher brake specific fuel consumption. On average, the emissions of CO, CO2, and HC of biodiesel are 17.8%, 3.41%, and 23.5% lower and NOx is 14.39% higher than the corresponding values obtained for pure diesel, respectively. In-cylinder combustion analyses show that the peak pressure of biodiesel is 0.5 MPa lower, the peak cycle temperature is 36 °C lower, the ignition delay is 4 °CA longer, the peak heat release rate is 16.5 J/deg. higher, and the combustion duration is 5.96 °CA longer compared to diesel combustion.

Large-eddy simulation of the injection timing effects on the dual-fuel spray flame

Large-eddy simulations (LES) coupled with a partially-stirred reactor model and a finite-rate chemistry are carried out to investigate the effects of n-heptane injection timing on the methanol fueled dual-fuel (DF) combustion. Methanol is premixed with air in a constant volume chamber (T=1000 K, ρ=14.8 kg/m3) to form a homogeneous mixture (equivalence ratio ϕm of 0.3). Liquid fuel n-heptane is provided from a high pressure injector to mimic the pilot fuel injection in DF engines. First, mesh sensitivity analysis and LES model validation are conducted. The experimental data of Spray-H (n-heptane fueled) from the Engine Combustion Network is used for model validation. It is shown that the present mesh and LES model are capable of replicating the liquid and vapor penetration length, mixture fraction, temperature distribution, pressure rise profile and ignition delay time (IDT). Second, the effects of n-heptane injection timing are investigated, by varying the start of injection (SOI) time. The LES results reveal that there are three stage heat releases in the DF combustion. With the delay of SOI, the mass fraction of hydrogen peroxide in the ambient mixture increases, leading to an early formation of hydroxyl. Therefore, the two-stage IDTs of n-heptane decrease, while the ambient methanol IDT increases. Results also show the cool flame and high-temperature flame evolution after methanol auto-ignition. The cool flame disappears while the high-temperature flame is found near the injector nozzle, which leads to a relatively high heat release rate.

Gasoline spray characteristics using a high pressure common rail diesel injection system by the method of laser induced exciplex fluorescence

The liquid and vapor phases of gasoline sprays were investigated using a common rail diesel injection system in a constant volume vessel by laser induced exciplex fluorescence (LIEF) and compared with diesel sprays. The effects of injection pressure and ambient pressure on gasoline sprays were measured under evaporating conditions. The results reveal that: the liquid phase penetration has a little change as the fuel is injected, while the vapor phase penetration increases constantly with obvious branch-like structures generated at the downstream vapor phase. The spray volume and mass of entrained gas both increase roughly linearly versus the mass of injected fuel. Compared with diesel sprays in similar conditions, gasoline sprays display a significantly shorter liquid penetration, while a smaller difference between the vapor penetration lengths of gasoline and diesel sprays is observed. The maximum equivalence ratio of gasoline sprays is still more than 2 at selected conditions. As the ambient pressure increases, the penetration lengths of liquid and vapor phases both reduce, and the mean equivalence ratio also decreases with a drop of spray volume. Conversely, the mass of entrained gas rises continually. With the increase of injection pressure, the liquid phase penetration length maintains almost no change. However, the vapor penetration length shows a declined trend during the injection pressure rise at iso-injected fuel mass condition. The spray volume and mass of entrained gas give a slight reduction when the injection pressure enhances. Oppositely, the mean equivalence ratio presents an increased tendency with similar mass of injected fuel.

A combined rate-shaping-splitting injection strategy for regulating stratification characteristics of fuel sprays

Producing a desired level of fuel stratification has recently aroused much interest to improve performance of combustion systems. In the present work, an injection strategy is proposed by combining the rate-shaping (IRS) and split-injection approaches for regulating the level and quality of stratification. An Eulerian-Lagrangian numerical model is detailed and calibrated against available experiments to study the effect of the uniform and combined IRS-splitting strategy parameters on spray characteristics. The results are analyzed carefully to identify the connection between the liquid and vapor penetration lengths (LL and VL) and the stratification parameters. We also try to reveal the physics underlying the variation of these parameters by the change of common design variables, like the ambient temperature and pressure, as well as by the variables specific to the IRS-splitting strategy. It is proven that the stratification parameter is a better measure of mixture inhomogeneity than VL. For instance, the proposed combined strategy is able to achieve a 50% increase in stratification while keeping the VL variation limited to 3%. Finally, our results demonstrate that the stratification can be effectively controlled by the combined strategy by adjusting the number of split injections and flow-rate coefficients of the main and pilot injections.

Numerical investigation of the effect of multi-walled carbon nanotube additive on nozzle flow and spray behaviors of diesel fuel

The thermal-physical properties of multi-walled carbon nanotubes (MCNTs) and MCNT blended diesel fuel were analyzed. Internal flow in injector Spray A of Engine Combustion Network and spray in a constant-volume chamber with considering the effect of the turbulence-induced breakup were modeled for pure diesel fuel and MCNT blended diesel fuel. Nozzle flow simulation showed that the addition of MCNTs into diesel fuel increased the flow turbulence at the nozzle hole outlet. Spray simulation statistically coupled with nozzle flow modeling showed that during stable spray development, there were a positive linear relationship between the liquid penetration length and the MCNT content in diesel fuel and a negative linear relationship between the Sauter mean diameter of the droplets and the MCNT content; the addition of MCNTs reduced the liquid cone angle and had an insignificant influence on the vapor penetration length.

Coupled in-nozzle flow and spray simulation of Engine Combustion Network Spray-G injector

A coupled Eulerian-Lagrangian approach was employed to Engine Combustion Network (ECN) Spray-G simulations. The Eulerian in-nozzle flow simulation was conducted with a small plenum attached to the nozzles, and the results were fed to the Lagrangian spray simulation. For Eulerian simulation, the homogeneous relaxation model (HRM) coupled with the volume of fluid (VOF) method was used. HRM proved to be good at predicting the phase change phenomena due to vaporization mechanisms, that is, both cavitation and flash boiling. As a one-way coupling, quantities such as rate of injection (ROI), mass injected through each hole, discharge coefficient, spray plume angle and half cone angle predicted from the Eulerian simulations were used as the initial and boundary conditions for the subsequent Lagrangian spray simulations using the blob injection model. Non-flashing (Spray-G1) and flashing (Spray-G2) spray was simulated, and the results were validated quantitatively against the published data in terms of the liquid and vapor penetration lengths, and good agreements were obtained. Furthermore, the simulation predicted the liquid and gas axial velocity and sauter mean diameter for Spray-G1 condition in agreement with the droplet size and particle image velocimetry (PIV) measurements from literature.

Numerical studies on unstable oscillatory direct contact condensation (DCC) of oxygen vapor jets in subcooled flowing liquid oxygen

At the booster turbopump exit of a high pressure staged combustion cycle based cryogenic rocket engine, hot gaseous oxygen after driving the booster turbine mixes with subcooled liquid oxygen from the booster pump leading to a complex phenomena of direct contact condensation of hot oxygen gas. The aim of the present investigation is to numerically study the condensation of oxygen vapor jets in subcooled liquid oxygen using a two-fluid two-phase model in the Eulerian framework to understand the mixing process at the booster turbopump exit. The unstable nature of the oxygen plume shapes at cryogenic temperatures have been examined and the stable to unstable transition in an unstable direct contact condensation cycle have been analyzed. A detailed parametric study has been conducted using the Box-Behnken design and suitable correlations are developed for the critical design parameters viz., overall averaged heat transfer coefficient and dimensionless maximum vapor penetration length. Finally, the maximum pressure oscillation amplitudes associated with unstable oscillatory oxygen direct contact condensation are characterized. The results of the present investigation will be helpful in designing experimental set-up for studying the unstable direct contact condensation at cryogenic temperatures and will serve as preliminary guidelines for the design of an oxygen direct contact condenser, which hitherto is unavailable in the open literature.

Analysis of Performance and Emission of Diesel Engines Operating on Palm Oil Biodiesel

<div class="section abstract"><div class="htmlview paragraph">Fast consumption of fossil fuels is demanding researchers to find few potential alternative fuels that meet sustainable energy demand in the near future with least environmental impact. Future energy system needs to be cost-efficient, renewable, and safe to handle. Biodiesel is expected to be the future energy source that meets all the environmental norms. The use of biodiesel in Internal Combustion (IC) engines represents an alternative clean energy source compared to hydrocarbon fuels that generate emissions such as carbon dioxide (CO<sub>2</sub>), carbon monoxide (CO), nitrogen oxides (NO<sub>X</sub>), Sulfur Oxides (SO) and particulate matters (PM). This paper describes the importance of Palm Oil Diesel (POD) as an alternative fuel source for diesel engines. Simulations are carried out with ANSYS FORTE software with POD. The engine chosen is a 26-kW diesel-gen-set. The engine geometry is drawn in SOLIDWORKS using dimensions of the actual diesel engine. Then, the geometry is imported in ANSYS FORTE and simulations are carried out with diesel and compared with the experimental data which shows around 97% accuracy. Then, a CHEMKIN file is created to use POD in ANSYS FORTE. Thereafter, simulations are carried out with POD with standard engine settings and compared with diesel. The engine performances are lower with POD due to lower calorific value, higher viscosity, higher density and heavier molecules present in POD. POD has a higher cetane number which is beneficial from the combustion point of view. In-cylinder pressure, temperature and accumulated heat release vs. crank angle are plotted to find out the combustion characteristics of POD and compared with diesel. The liquid and vapor penetration length, droplet size and mass are also plotted and compared with diesel.</div></div>

Computational Fluid Dynamics Studies on Unstable Oscillatory Direct Contact Condensation of Subsonic Steam Jets in Water Cross-Flow

Abstract In the last decade, researchers working on direct contact condensation (DCC) have focused their attention on studying the effect of liquid cross-flow, in contrast to the conventional stagnant liquid pool condensers. Currently, the major applications of DCC in liquid cross-flow include the sterilization process of milk and the mixing of oxygen-rich turbine drive gas with liquid oxygen (LOX) at the booster turbopump exit of a typical staged combustion cycle-based rocket engine. In this work, attempt has been made to develop and validate a two-fluid two-phase model for predicting the complex phenomena of steam injection into a cross-flow of subcooled water. A correlation for interaction length scale has been developed for DCC cases. The correlation includes the effect of all the critical operating parameters such as liquid subcooling, steam mass flux, and liquid velocity, which hitherto has not been available in the literature. The unstable nature of steam plumes has been investigated, and critical Weber numbers for predicting stable to unstable transition in a DCC cycle have been computed. The associated pressure and temperature oscillations due to unstable nature of plume have been studied. The critical design parameters for direct contact condenser such as the heat transfer coefficients and dimensionless vapor penetration lengths have been quantified and analyzed.

Experimental and Computational Investigation of Diesel and Gasoline Injection in a Direct Injection Compression Ignition Engine

In this paper, the numerical simulation of the diesel and gasoline fuels injection in a constant volume chamber and in a cylinder under the operating conditions of a compression ignition (CI) engine is conducted. The simulation results are compared with the experimental data which derived from fast imaging techniques. In order to check out the possibility of using gasoline instead of diesel to increase the volumetric efficiency of the CI engine, the spray characteristics of the gasoline and diesel with injection pressures of 40 and 80 MPa, as well as temperatures of 243, 273 and 313 K, under cold start condition is investigated. The results show that under the same conditions, the vapor penetration length for the two fuels is approximately equal and due to the lower volatility of the diesel fuel, its liquid penetration length in 40 and 80 MPa injection pressures was found to be 7 and 9 mm higher than gasoline, respectively. In addition, the reduction in fuel temperature from 313 K to 243 K leads an increase in the penetration of gasoline and diesel liquids by 12 and 10 mm, respectively. Finally, the decrease in the evaporation rate causes a non-homogeneous mixture and results an increase in the unburned hydrocarbons and emissions.

Flame–spray interaction and combustion features in split-injection spray flames under diesel engine-like conditions

In compression ignition engines, split-injection strategy has shown great benefits in reducing pollutant emissions and improving combustion efficiency. Spray–flame interaction involving in split injections is significantly complex, which affects the ignition process and even pollutant emissions. Therefore, the objective of this study is to investigate how the flame–spray interaction affects the subsequent ignition process and combustion features in split injections under diesel engine-like conditions. In this work, large eddy simulation coupled with a 54-species mechanism for split injections of n-dodecane is performed to study the effect of injection duration and dwell times (DTs) on spray–flame interactions and the ignition mechanism. The numerical model gives a reasonable agreement with the experiments in terms of the vapor penetration length, ignition delay times, mixture fraction distributions and the flame structures. The present study revealed that combustion for split injections is a multi-stage process and the ignition processes for the first and second injections are controlled by different mechanisms, namely autoignition for the first injection, and the accelerating ignition for the second injection due to the intermediate species and heating effect formed in the first injection. Moreover, the increase in dwell time between individual injections reduces the subsequently promoting ignition effect for the second injection and thus weakens the interacting process between the two injections. Consumption of the fuel in the first injection leads to a temperature increase and production of different species, which in turn accelerates the ignition of the second injection. Finally, the competition between the local flow timescale and chemical timescale is investigated based on the chemical explosive mode analysis (CEMA) methods. A balance between reaction and mixing processes dominates the combustion of the quasi-steady spray in the second injection with a short DT. However, the flame is controlled by autoignition when a longer DT is used.

Experimental and analytical study on liquid and vapor penetration of high-reactivity gasoline using a high-pressure gasoline multi-hole injector

Spray penetration length is an important parameter which is of great interest to both experimentalists and modelers. As it affects engine efficiency and emissions, measurement and prediction of spray penetration can significantly benefit engine optimization under various operating conditions. In this study, penetration length was investigated in a pre-burn constant volume combustion chamber using a gasoline multi-hole injector with high reactivity gasoline-like fuel designed explicitly for gasoline compression ignition (GCI) engines. Diffused back illumination (DBI) and shadowgraph were implemented for liquid and vapor phase penetration measurements, respectively. Different pre-burn gas mixtures are compared to investigate the influence of ambient gas properties on gasoline spray penetration under evaporating conditions. The liquid penetration under the gas composition of higher molecular weight tends to be longer. However, the vapor penetration showed insignificant effect under different gas compositions. Ambient gas temperature and gas composition were found to be an essential parameter for liquid phase penetration. Pressure difference was found to affect the vapor penetration length while its influence on liquid phase steady state penetration length at high ambient gas temperature is marginal. Statistical analysis was performed for both liquid and vapor phase penetration lengths, and a prediction model was developed with good agreement to the data under all test conditions.

Effect of injection pressure and ambient density on spray characteristics of diesel and biodiesel surrogate fuels

This paper presents novel experimental investigations on the influence of varying injection pressure and ambient density on evaporating sprays of diesel, tetradecane (as a diesel surrogate) and methyl oleate (as a biodiesel surrogate) fuels. Evidently, adapting high injection pressure and ambient density would remarkably enhance the atomization process, and in return improve the engine combustion, performance, and emission characteristics. Measurements were carried out in a rapid compression and expansion machine (RCEM) working under diesel engine-like conditions. Furthermore, a shadowgraph optical technique was applied, using a high-speed camera to capture the spray development at 20,000 frames per second (fps) to obtain the vapor penetration length, liquid penetration length and spray cone angle. The tested fuel was injected into a pressurized nitrogen gas in a diesel engine-like condition without combustion where the injection pressure and ambient density were varied from 50 MPa to 150 MPa, and from15 kg/m3 to 25 kg/m3, respectively. Results indicated that injection pressure and ambient density have a significant effect on the spray characteristics. Increasing the injection pressure from 50 MPa to 150 MPa results in the increase of vapor penetration by up to 33.2%, 21.5% and 24.4% for diesel, tetradecane and methyl oleate, respectively. Besides, increasing the ambient density from 15 kg/m3 to 25 kg/m3 results in a wider spray cone angle by up to 9.6%, 11.8% and 13.8%, for diesel, tetradecane and methyl oleate, respectively and a shorter vapor penetration by up to 9.2%, 11% and 13.1%, respectively. It is noticed that high injection pressure causes the least reduction in spray cone angle for biodiesel. The present measurements are considered bench-mark for validation of high-fidelity numerical simulation of diesel and biodiesel sprays.

Experimental study on the non-reacting spray characterization of gasoline compression ignition fuel

Gasoline compression ignition (GCI) engines have recently become a topic of interest due to its potential for very high thermal efficiencies with significant pollution reduction. High reactivity gasoline-like fuels with shorter ignition delay and similar volatility compared to market gasoline have been identified as a viable option for the GCI engines. To fully realize the potential of gasoline-like fuels in GCI engines, spray characterization of the fuel is needed for developing a better understanding of these fuels’ behavior in perspective of GCI engine applications. In this study, the spray characteristics of high reactivity gasoline-like fuel specially designed for GCI engines were investigated and compared with commercial gasoline fuel under non-reacting conditions. The new GCI fuel of RON 77 and E10 market gasoline of RON 91 were tested using a high-pressure custom-made multi-hole injector. The rate of injection, liquid and vapor penetration lengths were measured for both the fuels. It was found that the spray characteristics of GCI fuel are similar to that of the commercial E10 gasoline under non-reacting conditions.