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2017-11-13
Tech Insights
TI-0002
While all-electric aircraft remain at the bleeding edge of the aviation industry, incorporating technologies like proton exchange membrane fuel cells into existing aircraft can result in considerable auxiliary capability with low environmental impact. However, proper consideration must be given to supporting systems to achieve a reliable balance of plant-especially when those systems interface with existing aircraft architectures. The scope of the BoP is to manage and condition the reactant flows to and from the fuel-cell module and to provide power to system components.
2017-10-25
White Paper
WP-0002
The environmental impact of hydrocarbon-burning aircraft, both from the perspective of gas emissions and that of noise, is one of the main motivations for the move to electric propulsion. The added benefit from this shift to electric propulsion is that it has resulted in lowering the costs of electrical components such as motors, power electronic (PE) circuits, and batteries that are essential to this technology. This white paper seeks to explore the history, architecture, electrical components, and future trends of electric flight technology.
2017-10-08
Technical Paper
2017-01-2408
Lei Zhou, Hongxing Zhang, Zhenfeng Zhao, Fujun Zhang
Abstract The Opposed Piston Two-Stroke (OPTS) engine has many advantages on power density, fuel tolerance, fuel flexibility and package space. A type of self-balanced opposed-piston folded-crank train two-stroke engine for Unmanned Aerial Vehicle (UAV) was studied in this paper. AVL BOOST was used for the thermodynamic simulation. It was a quasi-steady, filling-and-emptying flow analysis -- no intake or exhaust dynamics were simulated. The results were validated against experimental data. The effects of high altitude environment on engine performance have been investigated. Moreover, the matching between the engine and turbocharger was designed and optimized for different altitude levels. The results indicated that, while the altitude is above 6000m, a multi-stage turbocharged engine system need to be considered and optimized for the UAV.
2017-10-08
Technical Paper
2017-01-2215
Mingming Ma
Abstract A lubricating system modeling method based on flight test data is proposed in this paper. ANN model based on a large number of flight test data is trained and validated, and models of 6 lubricating system parameters in all engine operation settings and whole flight envelope are established. Model results are in good agreement with flight test results, which shows feasibility and effectiveness of the presented modeling method. The model results are packaged in dynamic link library, and the coordination between calculating model and GDAS is accomplished. Comparison of model and flight test results in real-time monitoring of flight test comes true, thus on-line trend monitoring of oil parameters is implemented and applied. Additionally, input parameters are gradually decreased as new input parameter group of ANN structure. Oil parameter model is trained and validated again with the new group of parameters, until leading to unacceptable bias between model and flight test results.
2017-10-08
Technical Paper
2017-01-2318
Xiaoxu Jia, Zhong Huang, Dehao Ju, Zhen Huang, Xing-cai Lu
Abstract Combustion instability often occurs inside the combustion chamber of aero engine. Fuel atomization and evaporation, one of the controlling processes of combustion rate, is an important mechanism of the combustion instability. To tackle combustion instability, it challenges a deep understanding of the underlying mechanism of fuel atomization and evaporation. In this paper, acoustic field was established to simulate the pressure oscillation. Transient spray images of ethanol and kerosene were recorded using high-speed camera. The obtained images were processed by MATLAB to extract and analyze the related data. Spatial fuel atomization characteristics was analytically examined by multi-threshold image method to analyze the effect of the high frequency acoustic field on the fuel break-up and disintegration. The results show that the half spray cone angle on the side with speaker is suppressed by the presence of the imposed acoustic field compared with the case without speaker.
2017-10-08
Journal Article
2017-01-2293
Jim Barker, Jacqueline Reid, Sarah Angel Smith, Colin Snape, David Scurr, Graham Langley, Krina Patel, Anastarsia Carter, Cris Lapthorn, Frank Pullen
Abstract Studies of diesel system deposits continue to be the subject of interest and publications worldwide. The introduction of high pressure common rail systems resulting in high fuel temperatures in the system with the concomitant use of fuels of varying solubilizing ability (e.g. ULSD and FAME blends) have seen deposits formed at the tip of the injector and on various internal injector components. Though deposit control additives (DCAs) have been successfully deployed to mitigate the deposit formation, work is still required to understand the nature and composition of these deposits. The study of both tip and internal diesel injector deposits (IDID) has seen the development of a number of bench techniques in an attempt to mimic field injector deposits in the laboratory. One of the most used of these is the Jet Fuel Thermal Oxidation Tester or JFTOT (ASTM D3241).
2017-09-19
Technical Paper
2017-01-2029
Thibaut BILLARD, Cedric Abadie, Bouazza Taghia
Abstract The present paper reports non-electrically intrusive partial discharge investigations on aeronautic and electric vehicle motors fed by SiC inverter drive under variable environmental conditions. A representative test procedure and experimental set-up based on operating aeronautic conditions are essential to ensure the accuracy and reliability of partial discharge test on aircraft systems to make informed decisions on insulation system design choice. The aim of this paper is to demonstrate the feasibility of partial discharge test of the insulation system on a different type of motor under such conditions, both electrically and environmentally. To do so, the paper will start by detailing the innovative experimental set-up to be used in the study. It mainly consists in a high-voltage (1000V) inverter drive using SiC components to provide fast rise time surges.
2017-09-19
Technical Paper
2017-01-2033
Minh-khoa. Lam, Christopher Buterhaugh, Luis Herrera, Bang Tsao
Abstract The amount of electrical power required for future aircraft is increasing significantly. In this paper, a comprehensive model of a drive shaft with multiple degrees of freedom was developed and integrated to detailed engine and electrical network models to study the impact of higher electrical loads. The overall system model is composed of the engine, shafts, gearbox, and the electric network. The Dynamic Dual Spool High Bypass JT9D engine was chosen for this study. The engine was modeled using NASA’s T-MATS (Toolbox for the Modeling and Analysis of Thermodynamic Systems) software. In the electrical side, one generator was connected to the Low Pressure (LP) shaft and the other to the High Pressure (HP) shaft. A modified model of the shafts between the engine and the accessory gearbox was created.
2017-09-19
Technical Paper
2017-01-2030
Benjamin Cheong, Paolo Giangrande, Patrick Wheeler, Pericle Zanchetta, Michael Galea
Abstract High power density for aerospace motor drives is a key factor in the successful realization of the More Electric Aircraft (MEA) concept. An integrated system design approach offers optimization opportunities, which could lead to further improvements in power density. However this requires multi-disciplinary modelling and the handling of a complex optimization problem that is discrete and nonlinear in nature. This paper proposes a multi-level approach towards applying random heuristic optimization to the integrated motor design problem. Integrated optimizations are performed independently and sequentially at different levels assigned according to the 4-level modelling paradigm for electric systems. This paper also details a motor drive sizing procedure, which poses as the optimization problem to solve here. Finally, results comparing the proposed multi-level approach with a more traditional single-level approach is presented for a 2.5 kW actuator motor drive design.
2017-09-19
Technical Paper
2017-01-2039
Michael Sielemann, Changsoo Lee, Victor-Marie LeBrun, Chiwoo Ahn, Arnaud Colleoni, Dongkyu Lee, JeongSeok Lee, Anh Nguyen, Katrin Proelss, Hyon Min Yoon
Abstract Thermal management on aircraft has been an important discipline for several decades. However, with the recent generations of high performance aircraft, thermal management has evolved more and more into a critical performance and capability constraint on the whole aircraft level. Fuel continues to be the most important heat sink on high performance aircraft, and consequently the requirements on thermal models of fuel systems are expanding. As the scope of modeling and simulation is widened in general, it is not meaningful to introduce a new isolated modeling and simulation capability. Instead, thermal models must be derived from existing model assets and eventually enable integration across several physical domains. This paper describes such an integrated approach based on the Modelica Fuel System Library and the 3DExperience Platform.
2017-09-19
Technical Paper
2017-01-2042
Matthew Diggs
Abstract A newly-invented "X"-configuration engine utilizing the Scotch yoke mechanism renders potential for the best power/weight ratio of any piston engine. Due to its inherent space and weight efficiency, low stress levels on critical components and low bearing pressures, this new configuration can be designed for aircraft applications using high-pressure 4-stroke diesel cycle with large numbers of cylinders - as many as 24 or 32 cylinders - to minimize engine weight and cross-sectional area. Given the efficiency advantage of 4-stroke turbo-diesel cycle over turbine engines, a study reveals that diesel X-engines may be a preferable solution to turbine engines for airplanes, helicopters and UAVs up to approximately 60000 lbs max. weight @takeoff. Calculations using existing turbine-powered aircraft as a baseline indicate potential for 35 to 50% lower fuel consumption with no compromise to maximum takeoff weight, payload, range, cruise speed, maximum speed or takeoff power.
2017-09-19
Technical Paper
2017-01-2043
Pejman Akbari, Lucas Bermudes
Abstract Reducing the scale of the power engines, pose problems that are not encountered at large scale. Several effects, which are negligible at large scale, prove to dominate these viscous forces driven flows. Particularly, it is useful to investigate unsteady machines at small scales when subject to pressure waves. In this paper, the effects of scale on the propagation of shock waves in narrow shock tubes are studied using analytical and numerical modeling approaches. It is discussed how the size scale can become a decisive factor in governing the behavior of these small-scale devices. The results, in agreement with previous studies, suggest that the wall viscous stresses and heat conduction lead to deviation in flow characteristics compared to ideal shock wave behaviors observed in larger scales. The numerical results show shock-wave attenuation along the length of a narrow shock tube, in accordance with the developed analytical models.
2017-09-19
Technical Paper
2017-01-2048
Bryan Shambaugh, Patrick Browning
Abstract In this research, the magnetoplasmadynamic (MPD) effects of applying a toroidal magnetic field around an ionized exhaust plume were investigated to manipulate the exhaust profile of the plasma jet under near vacuum conditions. Tests for this experiment were conducted using the West Virginia University (WVU) Hypersonic Arc Jet Wind Tunnel. A series of twelve N52 grade neodymium magnets were placed in different orientations around a steel toroid mounted around the arc jet’s exhaust plume. Four different magnet orientations were tested in this experiment. Two additional configurations were run as control tests without any imposed magnetic fields surrounding the plume. Each test was documented using a set of 12 photographs taken from a fixed position with respect to the flow. The photographic data was analyzed by comparing images of the exhaust plume taken 10, 20, and 30 seconds after the plasma jet was activated.
2017-09-19
Technical Paper
2017-01-2044
Mithilesh Kumar Sahu, Tushar Choudhary, Sanjay Y
Abstract Aircraft engines powering propulsion of the aircraft is the key component of the system. In aircraft industry it is desirable that an aircraft engines should supply high speeds (for military fighters) with low maintenance (for civil airplanes). In this regard an integration of gas turbine engines with traditional propeller has been introduced and termed as turboprop engine. In present work, a gas turbine with cooled blading has been proposed to be the turboprop engine which has been exergoeconomically analyzed to assess the performance and economics related to the proposed turboprop engine. Exergo-economic analysis is a tool which combines thermodynamic analysis and economic principles to provide information that is helpful to predict thermodynamic performance and total cost of the engine (thermal system). The methodology includes energy, exergy and cost balance equations for component-wise modelling of whole system.
2017-09-19
Technical Paper
2017-01-2045
Shivam Mishra, Sanjay Y
Abstract Air-film cooled gas turbine is widely used in aero-derivative gas turbines. The present paper reviews previously developed air-film blade cooling models. The article further proposes a new blade cooling model for estimating blade coolant mass fraction which takes into account the effect of radiative heat transfer from hot flue gases to aero-derivative gas turbine blade surface. Various possibilities to achieve enhanced performance from aero-derivative gas turbine have been enumerated namely effect of advanced design philosophies, thermal barrier coatings, advancement in blade material. Also adoption of advanced design philosophies such as 3-D CFD would lead to improved component design. Further use of advanced blade material specifically for gas turbine blade application including single-crystal blade, directionally solidified blade material being nickel-chrome-molybdenum alloys may be explored.
2017-09-19
Technical Paper
2017-01-2046
Pejman Akbari, Ian Agoos
Abstract The Wave Disk Engine (WDE) is a novel engine that has the potential for higher efficiency and power density of power-generation systems. A recent version of wave disk engine architecture known as the two-stage WDE has been studied to address existing challenges of an existing WDE. After describing the engine operation, a cold air-standard thermodynamic model supporting the physical phenomena occurring inside the device is introduced to evaluate performance of the engine. The developed model is general and does not depend on the shape of the wave rotor, it can be applied to radial and axial combustion wave rotors integrated with turbomachinery devices. The analysis starts with predicting internal waves propagating inside the channels of the engine and linking various flow states to each other using thermodynamics relationships. The goal is to find analytical expressions of work output and efficiency in terms of known pressure and temperature ratios.
2017-09-19
Technical Paper
2017-01-2062
Tushar Choudhary, Mithilesh Sahu, Shreya KRISHNA
Abstract Gas turbine technology has traditionally been used by the aviation industry for powering the aircraft including acting as APU. Operational unmanned aerial vehicle (UAV) has a gas turbine which is used as Auxiliary Power Unit (APU) which generically have overall efficiency not exceeding 35% which limits the range in terms of time in the air for the same APU fuel carried onboard. Gas turbine exhaust heat energy is largely wasted and there is scope of its utilization by thermally coupling it with a solid-oxide fuel cell (SOFC). By coupling SOFC with the gas turbine (GT) based power system, a hybrid SOFC-GT based APU system has been proposed for thermodynamic analysis, and the thermal efficiency of the proposed system can be enhanced by 77%. This paper focuses on a thermodynamic cycle analysis of an internal reformed solid oxide fuel cell which is integrated with the gas turbine to form a hybrid APU system for an UAV.
2017-09-19
Technical Paper
2017-01-2063
Patrick Browning, Bryan Shambaugh, Joseph Dygert
Abstract The dielectric barrier discharge (DBD) has been studied significantly in the past two decades for its applications to various aerodynamic problems. The most common aerodynamic applications have been stall/separation control and boundary layer modification. Recently several researchers have proposed utilizing the DBD in various configurations to act as viable propulsion systems for micro and nano aerial vehicles. The DBD produces stable atmospheric-pressure non-thermal plasma in a thin sheet with a preferred direction of flow. The plasma flow, driven by electrohydrodynamic body forces, entrains the quiescent air around it and thus develops into a low speed jet on the order of 10-1 to 101 m/s. Several researchers have utilized DBDs in an annular geometric setup as a propulsion device. Other researchers have used them to alter rectangular duct flows and directional jet devices. This study investigates 2-D duct flows for applications in micro plasma thrusters.
2017-09-19
Technical Paper
2017-01-2065
Sebastian Bandycki, Michele Trancossi, Jose Pascoa
Abstract This paper presents a comparison between different hypotheses of propulsion of a spherical UAS. Different architectures have been analyzed assessing their specific aerodynamic, energetic, and flight mechanics features. The comparison has been performed assuming the robustness of flight control in different wind conditions, defining for each the specific operative ranges, mission profiles, and energy assessment. An effective energy assessment and comparison against a commercial UAS has been produced. Even if the paper considers a preliminary simplified configuration, it demonstrates clearly to be competitive against traditional quadcopters in a predefined reference mission.
2017-09-19
Technical Paper
2017-01-2141
Fengmei Li, Peng Ke
Abstract For the ice protection of the engine air induction part manufactured with low thermal conductivity composite material, the combined heating method using interior impingement and exterior air film has certain advantages. To study the influence of the external jet air film on the impingement characteristics of droplets, the numerical simulation method of three dimensional water droplet impingement based on Eulerian method was developed and verified by experimental data from references. The droplets impingement characteristics under three different blowing ratios and two different velocities were then investigated based on the configuration of 3D cylinder with two parallel jet holes.
2017-09-19
Technical Paper
2017-01-2123
Violet Leavers
Abstract The need to maintain aircraft in remote, harsh environments poses significant challenges. For example, in desert assignments or on-board carrier vessels where frequent rotation of staff with variable levels of skill and experience requires condition monitoring equipment that is not only robust and portable but also user friendly and requiring a minimum of training and skill to set up and use correctly. The mainstays of any on-site aircraft maintenance program are various fluid and particulate condition monitoring tests that convey information about the current mechanical state of the system. In the front line of these is the collection and analysis of wear debris particles retrieved from a component’s lubricating or power transmission fluid or from magnetic plugs. It is standard practice within the specialist laboratory environment to view and image wear debris using a microscope.
2017-09-19
Technical Paper
2017-01-2124
Violet Leavers
Abstract Within the aviation industry analysis of wear debris particles recovered from magnetic plugs and lubricating fluids is an essential condition monitoring tool. However, in large organisations, high staff turnover in remote work environments often leaves dangerous gaps in on-site support and background knowledge. The current work develops interactive software for wear debris particle classification, root cause diagnosis and serviceability prognostics. During the research several hundred wear debris particle images were collected, analysed and classified by a number of experts. At each stage of the analysis the experts were questioned about the knowledge and experience used to make their diagnoses and prognoses. The end result is an extensive knowledge base representing the combined expertise of a number of highly trained engineers, each with decades of hands-on experience.
2017-09-19
Technical Paper
2017-01-2130
Yucheng Liu, Thomas Sippel, Ge He
Abstract Oven and flame tests were designed and conducted to evaluate the heat resistance of a ceramic coating material, Cerakote C-7700Q, and evaluate its viability to replace the intumescent coating as one painting material for helicopter engine cowlings. The test results showed that the currently used painting scheme of the engine cowlings failed the 220°C oven test while after replacing the epoxy seal coat with the Cerakote, the new painting system passed the 220°C test in regards to painting bubbling. This study explained why serious appearance defects occurred in the inner skin of the engine cowling when the aircraft is hovering and suggested that one most time- and cost-effective solution is to repaint the current engine cowlings with a new three coating system of Cerakote, surface protection HS7072-622, and intumescent paint as a fireproof lacquer.
2017-09-19
Journal Article
2017-01-2036
William Schley
Abstract Of all aircraft power and thermal loads, flight controls can be the most challenging to quantify because they are highly variable. Unlike constant or impulsive loads, actuator power demands more closely resemble random processes. Some inherent nonlinearities complicate this even further. Actuation power consumption and waste heat generation are both sensitive to input history. But control activity varies considerably with mission segment, turbulence and vehicle state. Flight control is a major power consumer at times, so quantifying power demand and waste heat is important for sizing power and thermal management system components. However, many designers sidestep the stochastic aspects of the problem initially, leading to overly conservative system sizing. The overdesign becomes apparent only after detailed flight simulations become available. These considerations are particularly relevant in trade studies comparing electric versus hydraulic actuation.
2017-08-01
Journal Article
2017-01-9283
Peter R. Hooper
Abstract This paper reports on the research and development challenges experienced from dynamometer testing of a spark ignition UAV engine operating on heavy fuel. The engine is a segregated scavenging two stroke engine with air charge delivery by means of integral stepped pistons overcoming durability issues of conventional crankcase scavenged engines. A key element of the experimental study builds upon performance development to address the need for repeatable cold start on low volatility fuel thereby eliminating gasoline from UAV theatres of deployment. Lubrication challenges normally associated with crankcase scavenged two stroke engines are avoided by the integrated re-circulatory lubrication system. The fuel explored in this study is kerosene JET A-1.
2017-06-29
Journal Article
2017-01-9000
Teresa Donateo, Antonio Ficarella
Abstract The design of a hybrid electric powertrain requires a complex optimization procedure because its performance will strongly depend on both the size of the components and the energy management strategy. The problem is particular critical in the aircraft field because of the strong constraints to be fulfilled (in particular in terms of weight and volume). The problem was addressed in the present investigation by linking an in-house simulation code for hybrid electric aircraft with a commercial many-objective optimization software. The design variables include the size of engine and electric motor, the specification of the battery (typology, nominal capacity, bus voltage), the cooling method of the motor and the battery management strategy. Several key performance indexes were suggested by the industrial partner. The four most important indexes were used as fitness functions: electric endurance, fuel consumption, take-off distance and powertrain volume.
2017-06-05
Technical Paper
2017-01-1808
Francis Nardella
Abstract In a previous report, it was shown that power transmission through the camshaft reduced the first mode natural frequency of the power train and translated its convergence with dominant engine excitatory harmonics to a lower engine speed resulting in a marked reduction in torsional vibration while achieving 2/1 gear reduction for a 4-stroke 6-cylinder compression ignition (CI) engine for aviation. This report describes a sweep though 2 and 4-stroke engines with differing numbers of cylinders configured as standard gear reduction (SGRE) and with power transmission through the camshaft (CDSE) or an equivalent dedicated internal driveshaft (DISE). Four and 6-cylinder 4-stroke engines were modeled as opposed boxer engines. Four and 6-cylinder 2-stroke engines and 8, 10 and 12-cylinder 2-stroke and 4-stroke engines were modeled as 180° V-engines. All 2-stroke engines were considered to be piston ported and configured as SGRE or DISE.
2017-03-28
Technical Paper
2017-01-1311
Suman Mishra, Nagesh Gummadi, Lloyd Bozzi, Neil Vaughn, Rob Higley
Abstract Air rush noise is exhaust gas driven flow-induced noise in the frequency range of 500-6500 Hz. It is essential to understand the flow physics of exhaust gases within the mufflers in order to identify any counter measures that can attenuate this error state. This study is aimed at predicting the flow physics and air rush noise of exhaust mufflers in the aforementioned frequency range at a typical exhaust flow rate and temperature. The study is performed on two different muffler designs which show a significant air rush noise level difference when tested on the vehicle. The transient computational study was performed using DES with 2nd order spatial discretization and 2nd order implicit scheme for temporal discretization in StarCCM+. To compare with test data, a special flow test stand is designed so that all high and low frequency contents emanating from the engine are attenuated before the flow enters the test part.
2017-03-14
Journal Article
2017-01-9276
Joseph K. Ausserer, Marc D. Polanka, Jacob A. Baranski, Keith D. Grinstead, Paul J. Litke
Abstract The rapid expansion of the market for remotely piloted aircraft (RPA) includes a particular interest in 10-25 kg vehicles for monitoring, surveillance, and reconnaissance. Power-plant options for these aircraft are often 10-100 cm3 internal combustion engines. Both power and fuel conversion efficiency decrease with increasing rapidity in the aforementioned size range. Fuel conversion efficiency decreases from ∼30% for conventional-scale engines (>100 cm3 displacement) to <5% for micro glow-fuel engines (<10 cm3 displacement), while brake mean effective pressure decreases from >10 bar (>100 cm3) to <4 bar (<10 cm3). Based on research documented in the literature, the losses responsible for the increase in the rate of decreasing performance cannot be clearly defined.
2017-01-10
Technical Paper
2017-26-0336
Ganesh Liladhar Yewale, Abhishek Tapkire, D Radhakrishna, Popat Shejwal, Kaushal Singh, Gaurav Panchal
Abstract VRDE has developed Wankel type rotary engine to achieve high power output & fuel efficiency for indigenization programme of UAVs. This engine is meeting all performance parameters needed for intended aerial vehicle. This paper describes the testing methodology followed by development engineers to prove the endurance and reliability of UAV engine for airworthiness certification. This paper gives the brief about testing carried out on the Wankel engine, failures faced during endurance testing and their rectification to enhance the life of the engine to achieve hundred test cycle mark. This paper also briefs about the test set up, endurance test cycles simulating the practical operating conditions.
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