scholarly journals Insights into Single Droplet Impact Models upon Liquid Films Using Alternative Fuels for Aero-Engines

2020 ◽  
Vol 10 (19) ◽  
pp. 6698
Author(s):  
Daniela F. S. Ribeiro ◽  
André R. R. Silva ◽  
Miguel R. O. Panão
Keyword(s):  
Alternative Fuels ◽  
Fossil Fuels ◽  
Liquid Droplet ◽  
Pure Water ◽  
Liquid Films ◽  
Drop Impact ◽  
Experimental Conditions ◽  
Fluid Properties ◽  
Aero Engines ◽  
The Impact

In aero-engines, the introduction of biofuels is among the best alternatives to fossil fuels, and this change is likely to affect the impact of droplets on interposed surfaces. Under this framework, this work reviews the main morphological hydrodynamic structures occurring upon the impact of a liquid droplet on a wetted surface, using jet fuel and biofuel mixtures as alternative fuels. The experiments performed allow investigating the effect of the liquid film thickness on the dynamic behavior of single drop impact, considering the relevancy of these phenomena to the optimization of engine operating parameters. Particular emphasis is given to the occurrence of crown splash, and the morphological differences in the outcomes of drop impact depending on the impact conditions and fluid properties. The four fluids tested included pure water (as reference), 100% Jet A-1, 75%/25%, and 50%/50% mixtures of Jet A-1 and NExBTL (Neste Renewable Diesel)—with the Weber impact number between 103 and 1625; Reynolds values 1411–16,889; and dimensionless film thicknesses of δ = 0.1, 0.5, and 1. The analysis on the secondary atomization for the different fluids evidences the predominance of prompt and crown splash, and jetting for alternative fuels. Finally, besides a systematic review of empirical correlations for the transition to splash, we investigate their universality by extrapolating the validation range to evaluate their ability to predict the outcome of impact accurately. One of the correlations studied show the highest degree of universality for the current experimental conditions, despite its limitation to thin liquid films (δ=0.1).

scholarly journals Emission estimates and air quality impacts from the use of alternative fuels by the Titan cement factory in Thessaloniki

2013 ◽  
Vol 14 (2) ◽  
pp. 218-224
Keyword(s):  
Alternative Fuels ◽  
Fossil Fuels ◽  
Alternative Fuel ◽  
Cement Industry ◽  
Partial Replacement ◽  
Limit Values ◽  
Cement Factory ◽  
Pollution Levels ◽  
Fuel Substitution ◽  
The Impact

Cement production is an energy-intensive process. Utilisation of fossil fuels is common practice in the cement industry around the world. Alternative fuel substitution rates increase every year. More specifically, 18 % of the fuel used by the European cement industry in 2006 consists of alternative fuels. This study aims to investigate the prospects for the partial replacement of conventional fossil fuels currently used in the TITAN cement factory in Thessaloniki, Greece, with alternative fuels, focusing on the impact of alternative fuel use on the emissions of air pollutants from co-incineration operations. Air emissions were estimated for both the conventional fuel and mixtures of conventional fuel with alternative fuels, based on emission factors found in the literature but also using the measurements conducted by TITAN in 2010. Emission estimates indicate that legislative limit values for all pollutants are not exceeded. Based on the emission estimates and measurements in the flue gas, the dispersion of the plume around the factory has been described with an appropriate numerical simulation model. Results suggest that the factory’s contribution to the air pollution levels in the surrounding area is very low for most regulated pollutants.

A comparative study of the effect of compression ratio on the efficiency and flame development angle in a Cooperative Fuel Research engine fueled with binary gasoline–alcohol blends

2019 ◽  
pp. 146808741985910 ◽  
Author(s):  
Guillermo Rubio-Gómez ◽  
Lis Corral-Gómez ◽  
David Rodriguez-Rosa ◽  
Fausto A Sánchez-Cruz ◽  
Simón Martínez-Martínez
Keyword(s):  
Comparative Study ◽  
Compression Ratio ◽  
Alternative Fuels ◽  
Internal Combustion Engines ◽  
Fossil Fuels ◽  
Combustion Process ◽  
Spark Ignition ◽  
Spark Ignition Engine ◽  
Flame Development ◽  
The Impact

In the last few years, increasing concern about the harmful effects of the use of fossil fuels in internal combustion engines has been observed. In addition, the limited availability of crude oil has driven the interest in alternative fuels, especially biofuels. In the context of spark ignition engines, bioalcohols are of great interest owing to their similarities and blend capacities with gasoline. Methanol and ethanol have been widely used, mainly due to their knocking resistance. Another alcohol of great interest is butanol, thanks to its potential of being produced as biofuel and its heat value closer to gasoline. In this study, a comparative study of gasoline–alcohol blend combustion, with up to 20% volume, with neat gasoline has been carried out. A single-cylinder, variable compression ratio, Cooperative Fuel Research-type spark ignition engine has been employed. The comparison is made in terms of fuel conversion efficiency and flame development angle. Relevant information related to the impact in the combustion process of the use of the three main alcohols used in blends with gasoline has been obtained.

Displacement Behavior of Wood in Boss Forming Using Open-Die Wood Forging

2012 ◽  
Vol 504-506 ◽  
pp. 1261-1266 ◽  
Author(s):  
Shohei Kajikawa ◽  
Takashi Iizuka ◽  
Keisuke Yamaishi
Keyword(s):  
Moisture Content ◽  
Deformation Behavior ◽  
Alternative Fuels ◽  
Fossil Fuels ◽  
Experimental Conditions ◽  
Forming Temperature ◽  
Biomass Materials ◽  
Displacement Behavior ◽  
The Difference ◽  
Open Die Forging

Biomass materials such as wood are attracting renewed attention as alternative fuels in order to help resolve environmental resources caused by the use of fossil fuels. In this study, the possibility of products being processed from wood bulk was investigated by means of boss forming using open-die forging. Additionally, the difference in formability and deformation behavior during forging was investigated by changing the experimental conditions, such as the moisture content of the wood billets used, the forming pressure, and the forming temperature. The experimental results showed that wood had enough liquidity to be forged, and that two sudden and large increases in displacement occur during forging. Finally, the conditions governing these displacements were summarized from these results

scholarly journals Multiple Impinging Jet Air-Assisted Atomization

2017 ◽  
Author(s):  
Mário Costa ◽  
Bruno Pizziol ◽  
Miguel Panao ◽  
André Silva
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Alternative Fuels ◽  
Fossil Fuels ◽  
Cross Flow ◽  
Liquid Sheet ◽  
Air Mass ◽  
Breakup Mechanism ◽  
The Impact

The growth of the aviation sector triggered the search for alternative fuels and continued improvements in thecombustion process. This work addresses the technological challenges associated with spray systems and theconcern of mixing biofuels with fossil fuels to produce alternative and more ecological fuels for aviation. This workproposes a new injector design based on sprays produced from the simultaneous impact of multiple jets, using anadditional jet of air to assist the atomization process. The results evidence the ability to control the average dropsize through the air-mass flow rate. Depending on the air-mass flow rate there is a transition between atomizationby hydrodynamic breakup of the liquid sheet formed on the impact point, to an aerodynamic breakup mechanism,as found in the atomization of inclined jets under cross-flow conditions. The aerodynamic shear breakupdeteriorates the atomization performance, but within the same order of magnitude. Finally, our experiments showthat mixing a biofuel with a fossil fuel does not significantly alter the spray characteristics, regarded as a stepfurther in developing alternative and more ecological fuels for aero-engines.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4737

scholarly journals Splashing of a very viscous liquid drop impacting onto a solid wall wetted by another liquid

2017 ◽  
Author(s):  
Hannah M Kittel ◽  
Ilia V Roisman ◽  
Cameron Tropea
Keyword(s):  
Viscous Liquid ◽  
Internal Combustion Engines ◽  
Solid Wall ◽  
Drop Impact ◽  
Viscous Liquids ◽  
Low Viscosity ◽  
Wall Film ◽  
Fluid Properties ◽  
The Impact ◽  
Maximum Spreading

In this experimental work the main focus is on the impact of a single drop of a very viscous liquid onto a thin,horizontal wall film of different liquid. Splashing resulting from drop impact onto a wetted wall occurs in many natural and engineering applications like in internal combustion engines and spray cooling. While the splashing threshold for low viscosity liquid drops has been extensively examined, impact of a very viscous drop is much less studied. The viscosities of drop and wall film liquids are varied up to kinematic viscosities of 100,000 mm²/s. The liquids used in the experiments are miscible.The impact outcome is determined by the impact parameters and fluid properties. The effect of very viscous liquids used as drop fluid and as wall film liquid on the kinematic of the corona expansion is investigated in the experiments. The results of drop impact onto solid walls are compared to obtain the limiting asymptotic values for the splashing threshold. Finally, a semi-empirical model for the splashing threshold, for the maximum spreading radius Dmax and for the maximum spreading times tmax viscous liquids.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4702

Bubble Formation at Impingement of a Liquid Droplet on a Solid Surface

2000 ◽  
Author(s):  
Hitoshi Fujimoto ◽  
Tomoyuki Ogino ◽  
Osamu Takahashi ◽  
Hirohiko Takuda ◽  
Natsuo Hatta
Keyword(s):  
Solid Surface ◽  
Liquid Droplet ◽  
Droplet Diameter ◽  
Bubble Formation ◽  
Liquid Droplets ◽  
Vapor Bubbles ◽  
Experimental Conditions ◽  
Video Cameras ◽  
The Moment ◽  
The Impact

Abstract The collision of liquid droplets with a solid has been studied experimentally. The time evolution of the liquid/solid contact area as well as the shape of droplets has been observed by means of a flash-photographic method using two video cameras. It has been found that some air between the solid surface and the incoming droplet is entrapped at the moment of impact. In the case where the solid temperature is high (= 450 °C), numerous vapor bubbles appear at the liquid/solid interface after the collision. The bubble formation due to the entrapment of air has been examined for various experimental conditions. Water, and ethanol are used as test liquid. The droplet diameter is 2.4 mm for water and 1.9 mm for ethanol. The impact velocity varies from 0.8 to 3.1 m/s. The entrapment of air has been observed for both liquids under all conditions in the present study.

Influence of Alternative Fuels on the Liner Metal Temperatures in a V2500 Combustor

2021 ◽  
Author(s):  
Lukas Schäflein ◽  
Ludovic de Guillebon ◽  
Marco Konle
Keyword(s):  
Boundary Condition ◽  
Thermal Radiation ◽  
Alternative Fuels ◽  
Soot Formation ◽  
Cooling System ◽  
Minor Importance ◽  
Radiation Emission ◽  
Detailed Simulation ◽  
Aero Engines ◽  
The Impact

Abstract To reach ambitious emission goals, the use of sustainable aviation fuels (SAFs) is a short-term option in current aero engines. The combustion of such fuels can, due to their low soot formation, have an impact on the thermal radiation inside the combustor. This in turn can affect the combustor liner temperatures, which are directly linked to the lifetime of the combustor. To study the impact of SAFs, the authors numerically simulated the flow inside a V2500 aero engine combustor using an OpenFOAM-based solver capable of capturing multi-physics phenomena such as combustion, conjugate heat transfer, thermal radiation and soot formation. The complex cooling system of the V2500 combustor makes the evaluation of the wall temperatures extremely challenging. To achieve results with the resources available, the authors replaced the densely packed pins inside the cooling channel with a boundary condition. This boundary condition was derived from a highly detailed simulation of a section of the cooling system. With this model reduction, the wall temperatures could be evaluated at four operating points. Back-to-back comparisons of the predicted wall temperatures with pictures of deteriorated combustor hardware out of the field operation reveals the plausibility of the numerical results. Finally, this numerical model was extended to include the effects of thermal radiation and soot formation. To predict the combustion of Jet-A, both models were used with settings derived from former validation simulations. The SAF combustion with extremely low sooting level was mimicked by deactivating the soot formation completely. The comparison of the radiation source term reveals — as expected — locally a higher radiation emission in areas where soot is formed in the combustor. As consequence, this leads to higher net radiative heat flux into the combustor liners. However, due to its minor importance in the overall energy balance, this change did not lead to significantly different liner temperatures.

scholarly journals Droplet impact on flowing liquid films with inlet forcing: the splashing regime

Soft Matter ◽  
2017 ◽  
Vol 13 (41) ◽  
pp. 7473-7485 ◽  
Author(s):  
Idris T. Adebayo ◽  
Omar K. Matar
Keyword(s):  
Liquid Films ◽  
Drop Impact ◽  
Droplet Impact ◽  
Impact Dynamics ◽  
Spatial Structures ◽  
P Waves ◽  
Flowing Liquid ◽  
The Impact

Waves! Spatial structures on flowing liquid films contribute immensely to drop impact dynamics and notably alter the impact outcomes.

scholarly journals The Use of Biodrying to Prevent Self-Heating of Alternative Fuel

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3039 ◽  
Author(s):  
Teresa Gajewska ◽  
Mateusz Malinowski ◽  
Maciej Szkoda
Keyword(s):  
Alternative Fuels ◽  
Fossil Fuels ◽  
Calorific Value ◽  
Alternative Fuel ◽  
The Self ◽  
Process Efficiency ◽  
Self Heating ◽  
Maximum Temperatures ◽  
Refuse Derived Fuels ◽  
The Impact

Alternative fuels (refuse-derived fuels—RDF) have been a substitute for fossil fuels in cement production for many years. RDF are produced from various materials characterized by high calorific value. Due to the possibility of self-ignition in the pile of stored alternative fuel, treatments are carried out to help protect entrepreneurs against material losses and employees against loss of health or life. The objective of the research was to assess the impact of alternative fuel biodrying on the ability to self-heat this material. Three variants of materials (alternative fuel produced on the basis of mixed municipal solid waste (MSW) and on the basis of bulky waste (mainly varnished wood and textiles) and residues from selective collection waste (mainly plastics and tires) were adopted for the analysis. The novelty of the proposed solution consists in processing the analyzed materials inside the innovative ecological waste apparatus bioreactor (EWA), which results in increased process efficiency and shortening its duration. The passive thermography technique was used to assess the impact of alternative fuel biodrying on the decrease in the self-heating ability of RDF. As a result of the conducted analyses, it was clear that the biodrying process inhibited the self-heating of alternative fuel. The temperature of the stored fuel reached over 60 °C before the biodrying process. However, after the biodrying process, the maximum temperatures in each of the variants were about 30 °C, which indicates a decrease in the activity of microorganisms and the lack of self-ignition risk. The maximum temperatures obtained (>71 °C), the time to reach them (≈4 h), and the duration of the thermophilic phase (≈65 h) are much shorter than in the studies of other authors, where the duration of the thermophilic phase was over 80 h.

The role of viscosity and surface tension in bubble entrapment during drop impact onto a deep liquid pool

2007 ◽  
Vol 578 ◽  
pp. 119-138 ◽  
Author(s):  
Q. DENG ◽  
A. V. ANILKUMAR ◽  
T. G. WANG
Keyword(s):  
Surface Tension ◽  
Capillary Number ◽  
High Speed ◽  
Impact Crater ◽  
Pure Water ◽  
Cone Angle ◽  
Drop Impact ◽  
Inviscid Limit ◽  
Main Body ◽  
The Impact

The phenomenon of liquid drop impact onto the surface of a deep pool of the same liquid is studied in the context of bubble entrapment, using high-resolution digital photography. Three liquids, pure water, glycerin/water mixtures, and silicon oil, have been used to investigate the effect of viscosity (μ) and surface tension (σ) on regular bubble entrapment, and the associated impact crater signatures. The global viscous effect is seen as a shift in the classical inviscid bubble entrapment limits, whereas, at the impact crater, the local effect is seen as a weakening of the capillary wave, which is responsible for bubble pinching, and a weakening of the intensity of crater rebound. Bubble entrapment, which results from a competition between concentric capillary pinching of the crater cusp and viscous damping, is captured well by the capillary number Ca (Ca = mu Viσ, where Vi is the drop impact velocity). The measured peak entrapped bubble size decreases exponentially as capillary number increases, with the cut-off capillary number for bubble entrapment estimated to be around 0.6. The critical crater cone angle for peak bubble pinch-off weakly increases with capillary number, with the measured value in agreement with theory in the inviscid limit (low Ca). Additionally, the growth of the main body of the high-speed thin jet, formed immediately following bubble pinch-off, is fitted to a power-law singularity model. This suggests that the thin jet is similar to the hydraulic jets produced by the collapse of free-surface standing waves.

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