ESR 1: Onur Baran (CITY)
Onur earned his bachelor’s degree and master’s degree in Aerospace Engineering from Middle East Technical University (METU), Turkey. His studies mainly focused on experimental fluid dynamics and CFD analysis. He wrote his master thesis on the title “Experimental and Numerical Investigation of Coaxial Pressure Swirl Injectors”. He also worked as a research engineer at TUBITAK SAGE (Ankara) at the propulsion systems division. Since November 2020, Onur works as an Early Stage Researcher of EDEM project and pursues his PhD at the City, University of London.
Project Title: In-nozzle flow and near-nozzle atomisation characterisation in optical injector nozzles
Objectives: (1) To develop an experimental facility to visualize within and at the outlet region of real-size and enlarged orifices (2) To quantity the effect on in-nozzle phase change on spray atomisation and dynamics
Onur Baran is a PhD student at City, University of London. He is working on “In-nozzle flow and near nozzle atomisation characterization in optical injector nozzles”, under the supervision of Dr. Ioannis Karathanasis and Professor Manolis Gavaises.
Visualization of cavitation within the diesel injector nozzle is a challenging task since injection lasts in the order of milliseconds and the modern nozzle orifice diameters are less than 0.2 mm. Moreover, highly turbulent two-phase flow induces optical difficulties. These conditions make cavitation visualisation a challenging task. To overcome these challenges state-of-art visualisation techniques are needed to be utilized. In his research different imaging techniques are employed to investigate both in-nozzle flow and the near-nozzle spray characteristics.
Cavitating flow within a real-size optical single hole injector nozzle and real size optical multi-hole injector nozzle had been visualised simultaneously using high-speed diffuse-backlight illumination and Schlieren imaging. To elucidate the link between cavitation and the spray. The cavitating area and spray cone angle are calculated for every frame throughout the injection using recorded images.
Figure 1 shows the isometric and the section view of the multi-hole injector nozzle that used in the experiments.
Video 1 shows the cavitating real-size multi-hole injector nozzle and the calculated spray cone angle throughout the injection.
Video 2 shows the raw and post-processed images of the multi-hole injector in-nozzle flow side by side. The videos presented here were obtained using speed diffuse-backlight illumination, With post-process, binarised images of the raw images are obtained to calculate cavitating area.
Figure 1: Isometric and section views of the multi-hole injector (dimensions in mm)
ESR 2: Alexander Lauterkorn (BRUNEL)
Alexander earned his bachelor’s degree in Engineering in Nuremberg, Germany, in 2017, and he wrote his bachelor’s thesis „Thermal calculation of a radiator battery” within the Siemens AG. In 2019 he completed his master’s studies. The title of his master’s thesis, which he wrote within the Continental AG, is „Machine learning for an R744 circulatory system”. Since March 2020 he works as an Early Stage Researcher of the EDEM project and pursues his PhD at the Brunel University London.
Project Title: Optical measurements for injection and fuel mixing in transparent ICE
Objectives: (1) To visualise the in-cylinder mixture formation and combustion processes in a dual fuel engine with advanced injection strategies (2) To investigate the effect of premixed fuel properties on the dual fuel combustion processes
Alexander Lauterkorn comes from Germany and has been recruited by Brunel University (UK) to work on:„Optical measurements for injection and fuel mixing in transparent Internal Combustion Engine ICE”. Let’s have a look at the equipment he uses for his project.
Alexander and his research team are using a single cylindric optical engine to visualise the in-cylinder mixture formation and combustion processes in a dual fuel engine with advanced injection strategies and to investigate the effect of premixed fuel properties on the dual fuel combustion processes.
Figure 1 shows the side view of the engine on the left and the front view on the right. In the side view a 45⁰ angled mirror, located below an elongated piston with a silica window at the top, can be seen. This grants optical access to the combustion chamber in order to observe the Spray distribution as well as combustion events.
Figure 2 shows the elongated piston with the silica window. The experiments include Mie scattering and Laser Induced Fluorescence (LIF) to investigate the fuel distribution and mixture as well as combustion events.
Figure 1: Ricardo hydra optical engine
Figure 2: Elongated Piston with silica window in the top
ESR 3: Hamidreza Fajri (FAU)
Hamidreza studied Mechanical Engineering at Khajeh Nasir Toosi University of Technology, Iran, in the field of Vehicle Powertrain System. His master thesis was about the simulation of reactivity controlled compression ignition (RCCI) engines. During his master of science, he joined Irankhodro Powertrain Company, Iran, and pursued his studies in several majors including internal combustion engine, air flow field and engine 3D simulation. He also worked as a technical advisor for several master and Ph.D. students. He is currently enrolled in a PhD program at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), in collaboration with Perkins Engines Co Ltd, UK, and CPT Group GmbH, Germany, working on combustion and spray of dual fuel engines.
Project Title: Optical measurements for fuel mixing in CVC
Objectives: (1) To characterize the mixing process of the directly injected diesel with the ambient gas for different fuel and ambient gas compositions. (2) To quantify the effect of the intake gaseous stream thermodynamic properties on the mixing process with the pilot fuel
Hamidreza Fajri comes from Iran and currently is working as an EDEM researcher and a Ph.D. candidate at Friedrich-Alexander-Universität Erlangen-Nürnberg under Professor Michael Wensing’s supervision. His project is “Optical Measurements for Fuel Mixing in Constant Volume Chamber (CVC)” which is a part of the EDEM project.
There are two objectives of his project, the first is to investigate spray mixing of liquid pilot fuel (Diesel) in a gaseous environment within a CVC and the second is to characterize the ignition and combustion processes occurring in the CVC for natural gas/diesel mixtures at different substitution ratios.
Hamidreza is working at the Institute of Engineering Thermodynamics of FAU University, in his research team, they work with a constant volume combustion chamber of an inner volume of 10 Litres which is permanently scavenged with gas freely adjustable in its composition from air to pure nitrogen. The gas temperature and pressure can be varied independently from 298 K to 1000 K for temperature and from 30 kPa to 10 MPa for pressure. This chamber is variably equipped with different common rails and injectors. At five sides of the cubic chamber body, window flanges are mounted, while a flange with an injector housing is built in at the bottom side. The fuel temperature in the nozzle tip can be controlled in a range from 243 to 373 K via a thermostat and the maximum fuel pressure of 400 MPa can easily be adjusted.
All optical and laser measurements including Schlieren Photography, Mie Scattering, OH* Chemiluminescence, Natural Luminosity, Laser Induced Fluorescence and Raman Spectroscopy could be applied to detect spray development and combustion initiation and propagation.
Constant Volume Combustion Chamber (CVC):
ESR 4: Rafael Clemente Mallada (FAU)
Rafael took a degree in Aerospace Engineering with an Aerospace Prolusion concentration at the Technical University of Madrid (UPM-ETSIAE) in 2018. As bachelor’s Final Project he collaborated in an experimental study about passive scalars transportation in confined flows at laminar regime. A test rig was built and a series of experiments using the Particle Image Velocimetry technique were carried on. The results were published in a research article of the journal “Experimental Thermal and Fluid Science”. He pursued his studies at UPM and now he holds a MSc in Aeronautical Engineering. In 2019 he benefited from a collaboration within ETSIAE’s Thermo-fluid Dynamics Systems and Microsystems Research Group implementing a 2D9Q LBM code.
Currently he is enrolled to an EID partnered by Perkins Engines and Caterpillar Fuel Systems at Friedrich Alexander Universität, working within a leading research group in experimental investigation of high-pressure flows and laser diagnostic procedures in engine combustion.
Project Title: Optical measurements for ignition and combustion in RCM
Objectives: (1) To characterize the ignition and combustion processes of the pilot diesel with the gaseous-fuel primary under engine relevant conditions in a rapid compression machine (RCM). (2) To compare the RCM results to CVC results (collaboration with ESR3) and the results on emissions NOx and unburnt HC measured in engine test (collaboration with ESR2) in order to identify a possible correlation between RCM results and engine exhaust emissions database.
I am Rafa. I took a Bachelor’s degree in Aerospace Engineering and a Master’s degree in Aeronautics, both with an Aerospace Prolusion concentration, at the Technical University of Madrid (UPM-ETSIAE). Currently I am enrolled to an EID partnered by Perkins Engines and Caterpillar Fuel Systems at EDEM ITN as ESR 4, pursuing my PhD in DFICE at Friedrich Alexander Universität while working within a leading research group in experimental investigation of high-pressure flows and laser diagnostic procedures in engine combustion under the supervision of Prof. Dr.-Ing. Michael Wensing.
My project’s title is “Optical measurements for ignition and combustion in Rapid Compression Machine”. A RCM is an experimental device used to simulate the conditions in an ICE combustion chamber after the compression stroke. It is equipped to record the bulk gas pressure and the piston displacement. it is optically accessible as well, which makes it possible to film natural flame luminosity and OH radical chemiluminescence. Among other things, the output data can be used to analyse chemical kinetics, ignition delay, flame propagation and unburnt methane and soot emissions.
My tasks are the characterization of pilot fuel auto ignition and flame propagation under engine relevant conditions in a RCM. Both aiming to provide useful data to the simulation segments of the project and comparing RCM results with the project’s members in charge of the Combustion Chamber and optically accessible engines.
ESR 5: Raffaele Bellini (CITY)
Raffaele earned his bachelor’s degree in Mechanical Engineering and his master’s degree in Aeronautical Engineering from Politecnico di Milano, Italy. He has research experience in the numerical study of “FEM analysis relevant to Formula 1, Rally and NASCAR brake callipers” (Brembo S.p.A.), and of “the breakup of Aluminum Oxide in a multiphase and supersonic flow inside a Solid Rocket Motor” (Space Propulsion LABoratory, Politecnico di Milano). Raffaele is now pursuing his PhD at CITY in collaboration with Woodward L’Orange.
Project title: DNS for collapsing bubble dynamics and surface erosion for fuel mixtures
Objectives: (1) To develop an algorithm capable of resolving the collapse of a single and a cloud of bubbles (2) To validate the solver against published and newly obtained data. (3) To develop a sub-grid model for cavitation-induced erosion
Raffaele Bellini comes from Italy. He obtained both his BSc in Mechanical Engineering and his MSc in Aeronautical from Politecnico di Milano. After some time in the corporate world, he decided to pursue a PhD and he has been recruited by City, University of London (UK) to work on “DNS for collapsing bubble dynamics and surface erosion for fuel mixtures”.
Raffaele and his team are using @OpenFOAM as main software to perform their simulations, and the solver they implemented can be simply described as follows: an explicit density-based solver of the compressible Euler equations for multicomponent flows suitable for cavitation simulations (tabFoam) using the tabulated PC-SAFT energy Equation of State (EoS) for different fuels. Since EDEM is a very collaborative project, the tabulated data are provided by my colleague and friend @Vangelis Geber.
During his Project, Raffaele, has to carry out basically 3 objectives:
- To develop an algorithm capable of resolving the collapse of a single and a cloud of bubbles.
- To validate the solver against published and newly obtained data..
- To develop a sub-grid model for cavitation-induced erosion.
Figure 1, 2, 3, and show how Raffaele and his colleagues managed to resolve the collapse or a single bubble and a cloud of bubble and to validate the solver agains publised data.
ESR 6: Yu Jiao (TUM)
Yu Jiao earned his bachelor’s degree at China University of Mining and Technology in 2017. In 2020 he completed his master’s degree at Tianjin University, China. His research (related to the indirect air-cooling tower) won the National 1st Prize of a contest on Energy Saving & Emission Reduction, in the year 2015. His numerical studies (flow control and heat transfer enhancement) were published in International Journal of Heat and Mass Transfer(2019, 2020) and International Journal of Thermal Sciences(2020). Since 2016 he has been awarded twice the highest Chinese student honor “National Scholarship”, and he gained a full scholarship from Japan Science and Technology Agency to attend the “Japan-Asia Youth Science and Technology Exchange Program” in 2018. He currently works as an Early Stage Researcher of the EDEM project, pursuing a PhD at Technische Universität München.
Project title: DNS for fuel atomisation from dual-fuel injectors
Objectives: (1) To develop a numerical algorithm capable of handling spray/jet interaction and compressibility of all involved phases. (2) To Simulate fuel atomisation (primary break-up) for conditions relevant to dual-fuel engine conditions.
Our original in-house open source code CATUM has been validated many times in solving compressible two phase flow phenomena and turbulent flows, including the injection, cavitation and other cases. We will continue to develop CATUM to do high resolution simulation of the fully compressible multi-component flow with the opportunity to use LRZ computing system. And we expect to improve calculation efficiency through calculation optimization (MPI and shared memory programming OpenMP) or combining new robust algorithms.
ESR7: Hesham Gaballa (IFPEN)
Hesham earned a Bachelor of Science in Aerospace engineering from Cairo University, Egypt, in July 2018, achieving distinction with honours. He pursued a master’s degree in Fluid Mechanics and Energetics at Grenoble Institute of Technology (Grenoble INP), France, in September 2018. He carried out his six-month master’s internship at the department of aerodynamics and propulsion at ISAE-Supaero in Toulouse, France. The internship focused on the performance improvement of mini-aerial vehicles using the energy harvesting flight technique. The master’s thesis work relied on CFD simulations and wind-tunnel tests. He earned his master’s degree with distinction in September 2019. In January 2020, he joined IFP Energies Nouvelles in Rueil-Malmaison, France as a PhD student in the framework of the EDEM project.
Project title: Modelling of Dual-fuel jet breakup, phase-change, and mixing
Objectives:(1) To adapt suitable EoS for the prediction of short-chain alcohol flashing atomization. (2) Simulation of fuel atomization (primary break-up) for liquid/liquid fuel stream interaction relevant to dual-fuel engine conditions.
Hesham GABALLA is a Ph.D. student at IFP energies Nouvelles in France, working on “modeling of dual-fuel jet break-up, phase change and mixing” as a part of the EU “EDEM” project.
The main goal of the current work is to develop a multi-component two-phase flow model, which considers the real-fluid thermodynamics, phase change phenomenon, and primary atomization in dual-fuel configurations.
To this goal, the current work is based on the real-fluid model (RFM) developed at IFPEN and implemented in CONVERGE v3 CFD code. In the present work, the RFM two-phase flow model, closed by a thermodynamic equilibrium tabulation approach, is further developed to handle ternary mixtures as those encountered in dual-fuel engines.
As a first step, the RFM model has been applied to investigate the evaporation of n-dodecane droplets in a bi-component ambient (methanol + nitrogen) relevant to dual-fuel through highly resolved simulations (see video below). These simulations allow us to understand better the evaporation process and mixing of such ternary systems considering the real-fluid thermodynamics. In addition, they can serve as a reference for further development of droplet evaporation models for dual-fuel configurations.
The second step of this work aims to investigate the atomization, phase change of fuel jets in dual-fuel conditions. In this step, the RFM model will be coupled with a primary atomization model based on the surface density approach to investigate the atomization process in dual-fuel engines.
ESR8: Matteo Calabresi (AVL)
Matteo is a M.Sc. Aeronautical Engineer. In 2018 he graduated from La Sapienza – University of Rome, Italy, summa cum laude, presenting the thesis “Modelling turbulent flows in porous media”, which was partially carried out in Germany. He has been working in CFD since then, ranging over several applications and professional realities. Since the beginning of 2019, he has been employed by AVL – initially, by one of its affiliates – as software developer, involved in combustion modeling, and is currently an external PhD student at City University of London. He has mostly dealt with AVL Tabkin™, an FGM-based chemistry solver which generates thermo-chemistry tables looked-up on the fly by the CFD solver.
Project Title: Tabulated chemistry for dual-fuel combustion simulations.
Objectives: (1) Developing a formulation of the FGM model which allows the coexistence of multiple fuels in an IC engine (2) Building up a database of thermo-chemistry tables, using the dedicated model, accounting for a wide range of gaseous and liquid fuels which will be used for the further development of the project
Matteo Calabresi is an M.Sc. Aeronautical Engineer who has been recruited by AVL GmbH in Graz, Austria. In the meantime, he is enrolled at the CITY University of London to achieve a PhD in turbulent combustion. In the framework of the EDEM project he is working on the topic: “Tabulated chemistry for dual-fuel combustion simulations”.
The advantages of generating thermochemical lookup tables lie in the fact that, since the combustion time scales are significantly shorter that the fluid flow ones, chemistry can be solved in advance, populating the lookup table which will be only interpolated during the fluid dynamic simulation runtime. This allows for relevant calculation speedups, regardless of the degree of detail of the chemical mechanism used to generate the table (which can retain more than 15’000 chemical reactions).
Throughout the project, he will develop a novel methodology to account for multiple fuel streams and different combustion regimes, occurring inside a dual-fuel engine. The original model will be validated with experimental data provided by the other EDEM ESRs and other open-source databases.
The animation below depicts the temperature field and spray parcels of the well-known ECN Spray A testcase, solved with AVL FIRE™ coupled with the table generation tool AVL TABKIN™.
ESR9: Mehmet OZGUNOGLU (CHALMERS)
Mehmet earned his master’s degree in Defense Technologies from Istanbul Technical University. During his studies, turbulent combustion interaction in a reverse flow combustor is numerically investigated using LES methodology. He is currently an Early Stage Researcher and PhD student at Chalmers University of Technology within the concept of the EDEM project. Computational Fluid Dynamics applications of the Turbulent Flows are one of his main interests. His PhD project concerns computationally modelling of the cavitation-induced erosion phenomena for the dual-fuel injection systems.
Project Title: Simulation for erosion & durability of dual-fuel injection systems.
Objectives: (1) Implement an approach for the prediction of cavitation-induced erosion (2) Investigate cavitation erosion in injectors under dual-fuel operating conditions (3) Assess the effect of needle wobble on cavitation and cavitation erosion
Mehmet Ozgunoglu comes from Turkey and currently an Early-Stage Researcher and PhD student at Chalmers University of Technology within the concept of the EDEM project. Computational Fluid Dynamics (CFD) applications of the Turbulent Flows are one of his main interests. His PhD project concerns computationally modelling of the cavitation-induced erosion phenomena for the dual-fuel injection systems.
The ability to perform cavitation erosion assessment at the initial stage of the design process is highly advantageous. This allows for an early and cost-efficient detection of problematic design features. We are here evaluating the use of CFD methods. Besides the potential cost benefit, the additional flow details accessible through CFD improves the possibility of making good design changes.
As an initial step, an injector type test geometry is numerically investigated and compared with the existing experiments. Then, the simulations are further extended to see turbulence dynamics effects for this type of flow configuration. Cavitation erosion mechanisms are predicted with open-source CFD package OpenFOAM. In this modelling approach, “collapse detector algorithm” is selected as a primary tool to assess cavitation erosion. Here, the maximum surface pressure values are recorded on the solid boundaries, that are prone to cavitation erosion.
A picture below shows the maximum surface pressure values together with the vortical structures on the jet impingement region of test geometry.
Having modelling experience from aforementioned test study, high-speed industrial type of nozzles will be numerically investigated. High-fidelity simulations of these industrial nozzles will comprise two different (fixed) needle positions at the first stage, then the effect of the needle wobble motion will be included.
As a results of these studies, application of cavitation-induced erosion models with relevance to dual-fuel operating mode is going to be validated with experimental data.
Figure 1: Maximum surface pressure contour and vortical structures
ESR11: SARAH FEHÉR (IFPEN)
Sarah studied energy engineering at RWTH Aachen University, Germany, where she wrote her bachelor’s thesis about the modeling of confined rotating turbulent flows by large eddy simulation. She graduated in December 2020, after completing her master’s thesis on uncertainty analysis in life cycle optimization models with highest honors. She has also earned an engineering diploma with a specialization in propulsion systems from Ecole Centrale de Nantes, France, where she studied as a participant in the TIME double degree program.
During her studies, she has interned as a CFD engineer at PSA, developing aerothermal simulations for the prediction of fogging in automobile passenger cabins, and at Safran Aircraft Engines, where she researched the simulation of injection and atomization of two-phase fuel sprays.
Project Title: Modelling of Dual-Fuel Combustion by Large-Eddy Simulation
Objectives: (1)To propose an advanced modelling for dual-fuel combustion based on the Thickened Flame LES model (2) To apply the adapted TFLES model to various dual-fuel configurations including academic validations and industrial cases
Sarah is a PhD student working at IFP Energies Nouvelles and enrolled at Université Paris Saclay.
Dual fuel internal combustion engines present complex physics with multiple combustion regimes: A highly reactive pilot fuel spray is injected in a gaseous mixture of a low-reactivity fuel and air. The pilot fuel spray auto-ignites and in turn ignites the surrounding low-reactivity fuel mixture, leading to the propagation of a flame in the gaseous fuel mixture.
Simulating this combustion process is challenging but essential to predict the efficiency and environmental impact of dual-fuel engine concepts. However, available combustion models apply only to one specific combustion regime and are unable to handle the transition from auto-ignition of a spray to the propagation of a flame in a premixed gaseous fuel. Therefore, Sarah’s research focuses on the development of new combustion models suitable to capture multiple combustion regimes in the presence of two fuels.
Her approach is based on the Thickened Flame Model (TFM) for premixed flame propagation implemented in Converge v3 CFD code. The model will be developed at IFPEN using highly resolved DNS and LES simulations and validated against experimental data provided by other early stage researchers in the EDEM EU Project.
The resulting model will be applied to perform LES of large industrial combustion engines at Caterpillar, US, to estimate the environmental impact and reduction potential of dual-fuel concepts.
ESR12: Evangelos Geber (CITY)
Evangelos studied Mechanical Engineering at the National Technical University of Athens (NTUA), Greece, and graduated in 2019. Having chosen specialization in Air and Ground Transport Vehicles, he worked on numerous group projects regarding fluid dynamics, CFD analysis as well as general mechanical design. His diploma thesis focused on modern applications of CFD analysis, investigating external wind protection and wind comfort offered by a porous fence through numerical simulations. In addition, he was a member of the Formula Student team Prom Racing for 3 years, working on CFD simulations and aerodynamic design of a prototype race car. During the time, his team attended multiple international competitions and won numerous prices. He currently works as an EDEM Early Stage Researcher, pursuing his PhD at City University of London.
Project Title: Thermodynamics of fuel mixtures, their properties and modelling using the PC-SAFT EoS
Objectives: (1) To formulate a general fuel-property prediction methodology for high-pressure/temperature conditions (2) To formulate a numerical algorithm coupling the PC-SAFT EoS with a fluid flow solver
Hi my name is Vangelis Geber, I am half Greek and half German and have been recruited by CITY University (UK) as ESR12.
The title of my work is “Thermodynamics of fuel mixtures, their properties and modelling using the PC-SAFT EoS”. This probably sounds very confusing, so let’s explain it in a simple way.
I work on thermodynamics of fuels and fuel mixtures, like for example diesel and gasoline/ethanol blends. Because these fuels are too complicated to be modeled directly I use fuel surrogates, which are simpler single or multicomponent mixtures, designed to replicate the fuel properties. Using the PC-SAFT equation of state, combined with a Vapor-Liquid Equilibrium code and a transport property model, all the thermodynamic and transport properties of these surrogates are calculated. The results can be stored in a table like the one shown in Figure 1.
This information can later be used in CFD simulations of fuel injectors, providing the necessary precision in thermodynamic properties that is needed to capture jet characteristics as well as cavitation phenomena inside the injector nozzle. An example of such a simulation is shown in Figure 2
Figure 1: Fuel density as a function of pressure and temperature
Figure 2: Density field in a CFD simulation of a fuel jet
ESR13: Daniel Costero (POLIMI)
Daniel studied Aerospace Engineering at the Technical University of Madrid (UPM), Spain, with a major in Aerospace Vehicles. He pursued a dual master’s degree: at the UPM, with a major on Aerospace Propulsion, and at the ISAE-ENSMA (Poitiers) with a major on Combustion.
He worked as a research assistant at the Fluid Mechanics department at UPM applying Machine Learning techniques to geothermic problems. He completed his final thesis at ISAE-SUPAERO (Toulouse) working on the modelling of compressible effects on transonic flows with Deep Learning techniques, and he continued working there as a graduate researcher for 6 months. Currently, he is enrolled to a PhD program at Politecnico di Milano, in collaboration with Perkins Engines, working on the handling of dynamic meshes with topological changes and its application to Immersed Boundary Methods in order to accelerate the simulation of flows inside Internal Combustion engines.
Project Title: Methodology for automatic mesh refinement; application to simulation of combustion in dual-fuel engines
Objectives: (1) To test state-of-the-art methodologies for automatic mesh refinement to generate and treat dynamic grids in computational domains resembling dual-fuel engine geometries (2) To implement a novel methodology based on overset grids and automatic mesh refinement for efficient handling of dynamic grids with relevance to dual-fuel mixing and combustion simulations.
My name is Daniel Costero and I am a PhD student at Politecnico di Milano, in Italy, under the supervision of Prof. Piscaglia (He has linkedin so maybe you can tag him…). My PhD thesis is called “Development of CFD Methodologies for Dynamic Mesh Handing and Application to the simulation of Combustion in Dual-Fuel Engines” and is part of the EDEM project.
The first step in any CFD simulation is the creation of a mesh, discretizing the fluid in small parts on which the problem can be solved more easily. The quality of the mesh is a very important factor as it can introduce a large error in the solution. However, any engineer would take a lot of time to create this high-quality mesh, which is usually the most time-consuming task of the whole CFD process. This is why the first part of my work is to implement and validate an Automatic Mesh Generator able to provide a high-quality grid in a few seconds with very little user time.
If one wants to simulate the fluid inside an Internal Combustion Engine, the mesh must be continuously deformed to adapt to the movement of the boundaries, in this case the piston and the opening/closing of the valves. However, the high quality of the mesh bust be preserved during the whole engine cycle where the volume of the cylinder will change in a ratio around 20:1. The traditional way to deal with these large deformations is to stretch all the cells of the mesh, reducing the overall quality of the mesh.
To improve this aspect, the second part of my work aims to develop new ways of handling mesh deformation without deteriorating the mesh quality. We focus on a technique called dynamic layering or layer addition/removal that is shown in the video. Here, only a layer of cells is deformed and when its volume is bigger/smaller than a threshold value, a layer of cells is added/removed from the mesh, changing the total number of cells of the mesh. This methodology maintains a high-quality grid during the whole engine cycle but poses some challenges that I will try to overcome during the final part of my PhD.
In particular, the first challenge is to extend the methodology to high-order temporal schemes, as a discontinuity is introduced each time that a layer is added or removed. Then, some other techniques can be extended to work with dynamic layering. In particular, we will focus on adaptive mesh refinement (AMR) (shown in a video below) and Chimera grids, that improve the accuracy of the simulations in the most important regions without deteriorating the overall mesh.
ESR14: Marija Stipic (AVL)
Marija earned her master’s degree in Mechanical Engineering from the University of Zagreb, Croatia, with the highest honours in December 2019. During her studies in the Faculty of Mechanical Engineering and Naval Architecture, she completed internships at BMW in Munich and at Siemens in Hamburg. In the final year of her study she conducted the master’s thesis in the field of computational fluid dynamics. Since March 2020, she is pursuing her PhD studies as an Early Stage Researcher of the EDEM project at AVL Graz with the degree granted by the Technical University of Munich.
Project Title: Scalable simulation of engine emissions for a wide range of fuels and operating points
Objectives: (1) Coupling of URANS simulations and LES with detailed dual-fuel chemical kinetics (2) Extension of URANS models for auto-ignition/flame propagation transition in dual-fuel combustion utilising the flame thickening approach
Marija Stipic is pursuing her PhD studies as an Early Stage Researcher of EDEM Project at AVL GmbH in Graz with the degree granted by the Technical University of Munich. The topic of her PhD thesis is: “Scalable simulation of engine emissions for a wide range of fuels and operating points.”
In order to offer more thorough elucidation of interactions between turbulent mixing and chemical reactions during dual-fuel combustion Marija is performing Large Eddy Simulations (LES) and Partially Averaged Navier Stokes (PANS) simulations for the coupled in-nozzle flow, spray plume development, mixing and combustion in dual-fuel engines. The research is performed in several steps to get reliable and accurate approach for modeling turbulence and combustion processes in dual-fuel engine. Firstly, LES and PANS turbulence models should be coupled with detailed dual-fuel chemical kinetics, more specifically with the flamelet-generated-manifold (FGM) chemistry methodology for dual-fuel combustion. Secondly, LES and PANS models will be extended for autoignition/flame propagation transition in dual fuel-combustion utilizing the flame thickening approach (FTA). Finally, PANS approach will be compared to RANS and LES. This hybrid RANS/LES approach has a high chance to provide the optimum engine solution, e.g. proper turbulence/flame interactions, cycle-to-cycle variations etc. However, there are still some uncertainties in this modelling approach especially when it comes to definition of the cut-off resolution parameter. This will be thoroughly investigated. Figure displays instantaneous flow situation in a cut-plane across the cylinder axis at BDC for a number of selected engine cycles. In all engine cycles the structure and intensity of tumbling motion superimposed by smaller-scale vortex structures can be observed.
ESR15: Marilia Gabriela Justino Vaz (L’ORANGE)
Marilia Gabriela earned her bachelor’s degree in Metallurgical and Materials Engineering from Universidade Federal de Minas Gerais (UFMG) in Brazil, in 2015. During her undergraduate studies, she worked with CFD applied to ethanol engines and participated in two international exchange programs, in Portugal, and in France. Being keen on internal combustion engine development, she remained at UFMG and in 2018 she earned a master’s degree in Mechanical Engineering. In 2019 she worked on a contract basis for eleven months at Hochschule Heilbronn as a research engineer with numerical simulations and thermodynamic testing of variable compression ratio engines. Currently, she works at Woodward L’Orange in the EDEM project and is an external PhD student at CITY, University of London.
Project Title: Dual-fuel engine design concepts through effective CFD simulation tools.
Objectives: (1) To propose design concepts for novel dual-fuel engines for heavy-duty and marine dual-fuel engines (2) To optimize injection timing based on load and fuel mixture composition for maximum engine performance with reduced emissions
Gabriela Vaz comes from Brazil and has been recruited by Woodward L’Orange (Germany) for an industrial PhD under supervision of Dr. Foivos Koukouvinis from CITY, University of London. Her PhD topic is “Dual-fuel engine design concepts through effective CFD simulation tools”.
As part of the EDEM project, she is applying the advanced numeric models developed by the other ESRs to optimize the nozzle design for dual-fuel application. The geometry parameter of the nozzle influences directly the in-nozzle flow, jet break-up and fuel mixing, directly impacting on the combustion process, engine performance and emissions. Thus, these simulations tools help improve the fuel spray modelling for high-pressure systems, understanding better the phase-change phenomenon and fuel mixing in internal combustion engine.
One point already implemented is the real-fluid modelling via thermodynamic tabulation approach using the Perturbed Chain Statistical Associating Fluid Theory (PC-SAFT) equation of state (EoS). PC-SAFT predictions are more accurate to thermodynamics and transport fuel properties in comparison to cubic EoS, and the tabulation approach reduces considerable its computational cost.
ESR 16 Shenol Kyupeli (CITY)
Shenol earned his bachelor’s degree in Naval Architecture and Marine Engineering from Yildiz Technical University, Turkey. He pursued his master’s degree in Aerospace Engineering at University of Stuttgart, Germany, focusing on CFD analysis. He completed his master’s thesis at Von Karman Institute in Brussels, Belgium:“Integration of rotating detonation engines with HP-Turbines”.
He works as an Early-Stage Researcher of the EDEM project since August 2022 and pursues his PhD at City, University of London.
Project title: Hydrogen dual fuel injection