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77 Horváth Gábor, Körmöczi Andor, Vass Csaba, Geretovszky Zsolt LASER JOINING IN AVIATION: MAKING THE BATTERY PACKS OF THE ELECTRIC DRIVETRAIN This review provides a detailed overview on bonding techniques used for the assembly of battery packs of modern hybrid and full electric vehicles that are appearing in aviation with special attention towards the more modern laser techniques. We introduce conventional and modern welding and brazing procedures and compare them thoroughly. Among the available alternatives laser based techniques seem to be exceptionally promising due to their reliability, reproducibility and ease of automation, which we will also corroborate in this review. Our work is being supported by the EFOP project, entitled Research and development of disruptive technologies in the area of e-mobility and their integration into the engineering education. Keywords: Electric and hybrid aircraft, Lithium-ion battery cells, Battery assembly, Laser joining, Laser welding INTRODUCTION Nowadays, environmental friendly solutions are gaining more and more attention in every field of technology and research. Engineers and scientists are looking for new types of energy sources, mainly due to the dwindling supplies of fossil fuels and posing a smaller strain on nature. As a result, modern vehicles have alternative power sources, instead of conventional combustion engines, the most common of these constructions are hybrid or full electric drive systems. As of today we already see these trends in the car industry (Tesla Motors, Nissan, BMW, etc.) with the appearance of full electric automobiles even in the premium sector. This beginning trend is inevitably expanding and soon full or partially electric (hybrid) vehicles will take over the entire market. This change is present in aviation too, but the process is considerably slower, mainly due to the limited performance of energy storage units (accumulators) and the more critical importance of safety issues. Therefore currently hybrid drive systems are more common in the aviation sector with the full electric versions lagging behind. Hybrid vehicles usually have a conventional (combustion) drive system with an auxiliary low power electric motor, which works the same way as the full electric drive system. A simplified schematic electric drive scheme of a currently existing and operational full electric airplane (VUT 051 RAY) can be seen in Figure 1 [1]. Due to the above reasons these machines have a very limited flight time (typically less than an hour) and weight carrying capacity (around few hundred kilograms), but they fulfill 2 seater models perfectly, e.g. for the educational purposes of pilots [2]. Regarding the power source of the electric motor, the best engineering practice dictates to create the large capacity battery pack of several small capacity cells connected in parallel and/or in series instead of using one single large capacity unit. Using this method we gain a cost effective (the large scale production of small cells provides reduced costs), highly customizable (custom voltage and amperage values based on construction) and modular system which is exceptionally important given the fact that battery life of individual cells can be very different. These large capacity battery assemblies are produced using the multi-level production scheme presented in Figure 2 [3].

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147 Foroozan Zare, Árpád Veress PRELIMINARY INTRODUCTION TO VIRTUAL PROTOTYPING OF JET ENGINE COMPONENTS BY MEANS OF AERODYNAMIC DESIGN The goal of the present paper is to provide a short introduction about the ongoing research project in conjunction with virtual prototyping of jet engine components. Several sampling phases can be omitted by computational technology and so significant amount of cost, time and capacity can be saved. Although the steps of the presented process are performed for the components belong to different applications, it can be extended and used for certain engine and its parts also. A concentrated parameter distribution-type method has been developed and implemented to analyse the thermodynamic characteristics of a jet engine by considering the expected specification. Mass and energy balance with realistic thermodynamic conditions are applied in the analytical approach. Mean line design of the compressor and turbine unit can be performed, by which the geometrical sizes of the compressor and turbine will be the output of the method following the 3D extension of the blading. Based on the available dimensions, including the other components, the 3D model of the gas turbine can be prepared in a CAD software.following the verification of the design, CFD analyses can help to crosscheck the differences between the expected and the computed characteristics of the engine. The results of the simulations can be compared with the available measured and/or previously calculated data for validation and verification purposes and conclusions can be drawn about the accuracy and the efficiency of the used analytical and numerical methods.inverse design method is a preferable tool to increase static pressure rise, the mass flow rate per unit length in the vanned diffuser of the compressor unit. The results of the inverse design method can be verified by a commercial CFD code via specific test case. Keywords: Low-sized jet engine, engine design, CAD modelling, CFD, validation INTRODUCTION Many leading technologies are established in the aeronautical sector, wide spectrum of research and development are in progress in that areas [1][2], in which the propulsion systems of the aircrafts are also included. Todays, the application of the gas turbine engines has increased significantly. This is especially true for the jet engines, which are the only relevant propelling systems of the high power commercial and military airplanes today. ВД-7Б single spool turbojet engine from Rybinsk Motors are shown in Figure 1. Additionally, the gas turbines are utilized also in the other sectors as oil and gas in energy production. In spite of the fact that those engines in comparison with piston ones don t have similar level of thermal efficiency, they have substantial advantages in powerfulness, power density (power of the engine/mass of the engine), compactness, streamlining, simplicity and low maintenance cost demand. These engines are less sensitive for the overloads; they produce less vibration due to the well balanceable and rather axisymmetric rotational components. The gas turbines have high availability (97%) and reliability (> 99%), they have low emission (there is no lubricant in the combustion chamber and no soot during transient loads) they contain less moving parts and represent less sensitivity for the quality of the fuel compared to the piston engines. Additionally,

148 there is no need for liquid-based cooling system, but the maximum allowable temperature ( 1500 C) at the turbine inlet section must be limited due to the metallurgical reasons. Figure 1. Photo of the ВД-7Б single spool turbojet engine from Rybinsk Motors, Russia [3] Beside the technical characteristics of the gas turbines and its components today, certain amounts of potentials are available for improving their efficiencies, performances and emissions over the wider range of operational conditions [4][5]. Although the experiences and the know-how of the gas turbine manufacturers increasing continuously, the different mathematical models with using of optimum choice and form of the most dominant processes can significantly contribute to decrease the cost, time and capacity in the early phase of gas turbine design and developments. The main goal of the present ongoing research is to introduce a design procedure and analysis of a jet engine and its components by means of virtual prototyping. DEVELOPMENTS OF A CONCENTRATED PARAMETER-DISTRIBUTION TYPE METHOD A thermodynamic model has been developed and implemented in MATLAB environment for determining the main characteristics of single spool, dual spool turbofan, and triple spool turbojet engines w/wo afterburner at start position. The mass, energy balance and the real thermo dynamical processes are used in the concentrated parameter distributions type model. Ambient conditions, incoming air mass flow rate, pressure ratio of the compressor, turbine inlet total temperature, the length and diameter of the engine is used as available input parameters of the analyses. The material properties as specific heats and the ratio of the specific heats are depends on the temperature and component mass fraction and so they are determined by iteration cycles. Mechanical, isentropic and burning efficiencies, pressure losses, the bleed air ratio for technological reasons, air ratio for blade cooling, fan and intermediate compressor pressure ratios (if they are the cases), the afterburner temperature and power reduction rate of the auxiliary systems are involved as unknown parameters in the specifications. Hence, nonlinear constraint optimization is applied for determining the mentioned values by means of fitting the calculated thrust and thrust specific fuel consumption to the known parameters, which are available in the technical documents. The results of the optimization show that available and the resulted thrusts and thrust specific fuel consumptions are close to each other, the differences between them are below 5% as it is shown in the Table 1 for the engines ВД-7 and РД-9Б for example. The thermodynamic cycle of the specific engines can be plotted in T-s diagram (see Figure 2 for the ВД-7 engine). The processes between the engine-states denoted by numbers are plotted by

258 CARBONDIOXIDE AS THE MOST IMPORTANT ADVERSARY WE FACE OR WHAT IS THE ROLE OF "CORSIA" ESTABLISHED BY ICAO IN THIS BATTLE Unfortunately, the aviation by the combusted fuel produces a lot of the pollutants released into the atmosphere. Considering climate change, the most serious problem is the carbon dioxide emissions. This amount can be reduced only by burning less fuel, but considering the predicted growth rate of aviation, the amount of CO 2 will increase by three times in the next 30 years without further action. In light of this, ICAO and its Member States, with relevant organizations, would work together to strive to achieve a collective medium term global aspirational goal of keeping the global net CO 2 emissions from international aviation from 2020 at the same level (so-called "carbon neutral growth from 2020"). In this paper, we deal mainly with one of the branches of these measures, the so-called Market Based Measures (MBM), namely the CORSIA (Carbon Offsetting and Reduction Scheme of International Aviation). Keywords: international aviation industry, climate change, carbon dioxide emission, ICAO, CORSIA, Market Based Measures, Carbon Offsetting Varga Béla (PhD) Egyetemi docens Nemzeti Közszolgálati Egyetem Hadtudományi és Honvédtisztképző Kar Katonai Repülő Intézet Sárkány-hajtómű Tanszék varga.bela@uni-nke.hu orcid.org/ Tóth József (MSc, MBA) gyakorlati oktató Nemzeti Közszolgálati Egyetem Hadtudományi és Honvédtisztképző Kar Katonai Repülő Intézet Repülő Sárkány-hajtómű Tanszék toth.jozsef@uni-nke.hu orcid.org/ Varga Béla (PhD) Associate professor National University of Public Service Faculty of Military Science and Officer Training Institute of Military Aviation Department of Aircraft and Engine varga.bela@uni-nke.hu orcid.org/ Tóth József (MSc, MBA) Practical instuctor National University of Public Service Faculty of Military Science and Officer Training Institute of Military Aviation Department of Aircraft and Engine toth.jozsef@uni-nke.hu orcid.org/ A GINOP A légiközlekedés-biztonsághoz kapcsolódó interdiszciplináris tudományos potenciál növelése és integrálása a nemzetközi kutatás-fejlesztési hálózatba a Nemzeti Közszolgálati Egyetemen VOLARE című projekt az Európai Unió támogatásával, az Európai Regionális Fejlesztési Alap társfinanszírozásával valósul meg. A kutatás a fenti projekt AVIATION_FUEL nevű kiemelt kutatási területén valósult meg. 041b061a72