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2017-06-05
Technical Paper
2017-01-1765
Albert Allen, Noah Schiller, Jerry Rouse
Corrugated-core sandwich structures with integrated acoustic resonator arrays have been of recent interest for launch vehicle noise control applications. Previous tests and analyses have demonstrated the ability of this concept to increase sound absorption and reduce sound transmission at low frequencies. However, commercial aircraft manufacturers often require fibrous or foam blanket treatments for broadband noise control and thermal insulation. Consequently, it is of interest to further explore the noise control benefit and trade-offs of structurally integrated resonators when combined with various degrees of blanket noise treatment in an aircraft-representative cylindrical fuselage system. In this study, numerical models were developed to predict the effect of broadband and multi-tone structurally integrated resonator arrays on the interior noise level of cylindrical vibroacoustic systems.
2017-06-05
Technical Paper
2017-01-1808
Francis Nardella
In a previous report, it was shown that power transmission through the camshaft reduced the first mode natural frequency of the powertrain and translated its convergence with dominant engine excitatory harmonics to a lower engine speed resulting in a marked reduction in torsional vibration for geared 6 cylinder compression ignition engines 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). Four and 6 cylinder engines were modeled as opposed boxer engines and 8, 10 and 12 cylinder engines were modeled as 180-degree V-engines. Mass-elastic models of the different engine power train configurations were modeled using the torsional vibration module in Shaft Designer obtained from SKF (Svenska Kullagerfabriken). Crankshaft, camshaft, gearing, pistons, piston pins and connecting rods with bolts were modeled in Solidworks.
2017-06-05
Technical Paper
2017-01-1766
Dirk von Werne, Stefano Orlando, Anneleen Van Gils, Thierry Olbrechts, Ivan Bosmans
Methodology to secure cabin noise and vibration targets is presented. Early in the design process, typically in the Joint Definition Phase, Targets are cascaded from system to component level to comply to the overall cabin noise target in various load cases. During the Detailed Design Phase, 3D simulation models are build up to further secure and refine the vibro-acoustic performance of the cabin noise related subsystems. Noise sources are estimated for the target setting based on analytical and empirical expressions from literature. This includes various types of engine noise – fan, jet, and propeller noise – as well as turbulent boundary layer noise. For other noise sources, ECS and various auxiliaries, targets are set such as to ensure the overall cabin noise level. To synthesize the cabin noise, these noise sources are combined with estimates of the noise transfer through panels and the cavity effect of the cabin. This part is again based on analytical and empirical formulations.
2017-06-05
Technical Paper
2017-01-1764
Himanshu Amol Dande, Tongan Wang, John Maxon, Joffrey Bouriez
The demand for quieter interior cabin spaces among business jet customers has created an increased need for more accurate prediction tools. In this paper the authors will discuss a collaborative effort between Jet Aviation and Gulfstream Aerospace Corporation to develop a Statistical Energy Analysis (SEA) model of a large commercial business jet. To have an accurate prediction, it is critical to accurately model the structural and acoustic subsystems, critical noise transmission paths and dominant noise sources on the aircraft. The geometry in the SEA model was developed using 3D CAD models of major airframe and interior cabin components. The noise transmission path was characterized through extensive testing of various aircraft components in the Gulfstream Acoustic Test Facility. Material definitions developed from these tests became input parameters in the SEA model.
2017-03-28
Technical Paper
2017-01-1347
Jianhua Zhou, Min Xu, Bao Wang
Abstract Conventionally, the engines are calibrated under the assumption that engines will be made exactly to the prints, and all the engines from the same batch will be identical. However, engine-to-engine variations do exist which will affect the engine performances, and part-to-part variations, i.e., the tolerance, is an important factor leading to engine-to-engine variations. There are researches conducted on the influence of dimensional tolerances on engine performance, however, the impact of straightness, which is an important geometric tolerance, on lubrication is an unsolved issue. This study presents a systematic method to model the straightness and to analyze its effects on the friction loss. The bearing model is built based on elastohydrodynamic (EHD) theory. Meanwhile a novel modeling method to represent any form of straightness in three-dimensional space is proposed.
2017-03-28
Technical Paper
2017-01-1592
Jingdong Cai, Saurabh Kapoor, Tushita Sikder, Yuping He
Abstract In this research, active aerodynamic wings are investigated using numerical simulation in order to improve vehicle handling performance under emergency scenarios, such as tight cornering maneuvers at high speeds. Air foils are selected and analyzed to determine the basic geometric features of aerodynamic wings. Built upon the airfoil analysis, the 3-D aerodynamic wing model is developed. Then, the virtual aerodynamic wings are assembled with the 3-D vehicle model. The resulting 3-D geometry model is used for aerodynamic analysis based on numerical simulation using a computational fluid dynamics (CFD) software package. The CFD-based simulation data and the vehicle dynamic model generated are combined to study the effects of active aerodynamic wings on handling performance of high-speed vehicles. The systematic numerical simulation method and achieved results may provide design guidance for the development of active aerodynamic wings for high-speed road vehicles.
2017-03-28
Journal Article
2017-01-0204
Gaurav Gosain, Billy Holland, Thomas McKinley
Abstract Understanding customer usage space and its impact on engine, after treatment, and vehicle duty cycles poses challenges in terms of data noise, data variability and complex interrelations. Moreover, humans are only able to concurrently visualize at most 2 to 3 dimensions, limiting the number of engine parameters that can be considered. Previous studies in this field have been limited to understanding trends in data based on single duty cycle, comparatively short application period and time domain segmented clustering analysis. These techniques have been used to determine representative cycles for specific applications. In this paper, K-Means Clustering is used to classify customer usage space based on tens of dimensions, for multiple duty cycles, and over years of operation. The clusters are evaluated based on system, sub-system, and component-based metrics on a day based unsegmented engine parameter values.
2017-03-28
Journal Article
2017-01-1512
Fuliang Wang, Zhangshun Yin, Shi Yan, Jia Zhan, Heinz Friz, Bo Li, Weiliang Xie
Abstract The validation of vehicle aerodynamic simulation results to wind tunnel test results and simulation accuracy improvement attract considerable attention of many automotive manufacturers. In order to improve the simulation accuracy, a simulation model of the ground effects simulation system of the aerodynamic wind tunnel of the Shanghai Automotive Wind Tunnel Center was built. The model includes the scoop, the distributed suction, the tangential blowing, the moving belt and the wheel belts. The simulated boundary layer profile and the pressure distribution agree well with test results. The baseline model and multiple design changes of the new Buick Excelle GT are simulated. The simulation results agree very well with test results.
2017-03-28
Journal Article
2017-01-1546
Joshua Newbon, David Sims-Williams, Robert Dominy
Abstract The effect of the upstream wake of a Formula 1 car on a following vehicle has been investigated using experimental and computational methods. Multiple vehicle studies in conventional length wind tunnels pose challenges in achieving a realistic vehicle separation and the use of a short axial length wake generator provides an advantage here. Aerodynamic downforce and drag were seen to reduce, with greater force reductions experienced at shorter axial spacings. With lateral offsets, downforce recovers at a greater rate than drag, returning to the level for a vehicle in isolation for offsets greater than half a car width. The effect of the wake was investigated in CFD using multiple vehicle simulations and non-uniform inlet boundary conditions to recreate the wake. Results closely matched those for a full two-vehicle simulation provided the inlet condition included unsteady components of the onset wake.
2017-01-10
Technical Paper
2017-26-0279
Onkar P Bhise, S Ravishankar
Abstract Polytetrafluoroethylene (PTFE) is used extensively as the inner tube material in various Aerospace and Industrial hose constructs. The fluoropolymer exhibits various unique mechanical properties from other fluoropolymers including chemical inertness, non-adhesiveness and low friction coefficient making it an attractive solution for hose applications. PTFE material can be modeled using various material modeling approaches including linear-elastic, hyperelastic and viscoplastic depending on the level of accuracy required in predicting material response. Fluoropolymers, like PTFE, are considered viscoelastic-viscoplastic materials. In other words, the material exhibits both viscous and elastic characteristics when undergoing deformation but also possesses behavior in which the deformation of the material also depends on the rate by which loads are applied.
2016-11-08
Technical Paper
2016-32-0006
Ran Amiel, Leonid Tartakovsky
Abstract This paper provides an analysis of the effect of a flight altitude on knock occurrence in reciprocating SI turbocharged engines. It presents results of the computational study aimed at investigating reasons leading to knock occurrence and methods of alleviating the knock tendency of small aircraft engines. Turbochargers are frequently used to improve the performance of aviation platforms at high altitudes. Although a turbocharger provides the benefits of increased power, improved BSFC and a downsized engine, it can result in engine knock because of increasing the intake air temperature, due to a rise in the compression ratios as the air density drops. Aerial platforms experience environmental conditions that can change drastically in a matter of a few minutes. Therefore, it is important to be aware of the combined effects of altitude, initial ground temperature, humidity, flight velocity and fuel octane numbers on the emergence of knock following takeoff.
2016-10-25
Technical Paper
2016-36-0293
Eloy Martins de Oliveira Junior, Marcelo Lopes de Oliveira e Souza
Abstract Cyber-physical systems are joint instances of growing complexity and high integration of elements in the information and physical domains reaching high levels of difficulty to engineer an operate them. This happens with satellites, aircraft, automobiles, smart grids and others. Current technologies as computation, communication and control integrate those domains to communicate, synchronize and operate together. However, the integration of different domains brings new challenges and adds new issues, mainly in real time distributed control systems, beginning with time synchronization. In this paper, we present a discussion on time synchronization and their effects in distributed cyber-physical control systems. To do that, we review the literature, discuss some time synchronization techniques used in cyber-physical systems, and illustrate them via model and simulation of a system representative of the aerospace area.
2016-10-25
Technical Paper
2016-36-0282
Suely M. C. Romeiro, Marcelo L. de Oliveira e Souza
Abstract Modeling and Simulation - M&S is recently gaining more importance and emphasis as an essential method for developing engineering systems especially for aerospace and automotive systems, due to their complexity, integration and even human involvement. The main reasons for M&S having that important role nowadays are: 1) M&S can predict system behavior and possible problems. Therefore, it can reduce time and cost for developing systems, it can avoid future corrections into systems, as well. 2) M&S can be used for conception, training, maintenance, etc., requiring less expensive tools and previously preparing people to the real scenario. 3) When it comes to situations that involve aerospace or other products, where high costs are involved, mistakes can be avoided or at least minimized. Summarizing, M&S can reduce project cost and schedule, and improve quality.
2016-10-25
Technical Paper
2016-36-0377
Alain Giacobini Souza, Luiz Carlos Gadelha Souza
Abstract In designing of the Attitude Control System (ACS) is important take into account the influence of the structure’s flexibility, since they can interact with the satellite rigid motion, mainly, during translational and/or rotational maneuver, damaging the ACS pointing accuracy. In the linearization and reduction of the rigid-flexible satellite mathematic model, usually one loses some important information associated with the satellite true dynamical behavior. One way to recovery this information is include to the ACS design parametric and not parametric uncertainties of the system. The H infinity control method is able to take into account the parametric uncertainty in the control law design, so the controller becomes more robust. This paper presents the design of a robust controller using the H infinity control technique to control the attitude of a rigid-flexible satellite.
2016-10-25
Technical Paper
2016-36-0437
Gustavo de Carvalho Bertoli, Geraldo José Adabo, Gefeson Mendes Pacheco
Abstract A method for conceptual design of Solar Powered Unmanned Aircraft System (UAS) is presented. This method is based on traditional design methodology - wing loading estimation for preliminary sizing - modified for Solar Powered UAS case. Based on past works on Solar Powered UAS design, proposes a method that considers payload power consumption and therefore its impact on battery sizing. This battery sizing composes vehicle conceptual sizing equation. This method is useful for an assessment of Solar Powered UAS use in specific missions and serving as a start point for a more detailed design. A user interface was developed to automate the design process based on this method proposed.
2016-10-25
Technical Paper
2016-36-0402
Jairo Cavalcanti Amaral, Marcelo Lopes de Oliveira e Souza
Abstract Switching controls are those that can switch between control or plant modes to perform their functions. They have the advantage of being simpler to design than an equivalent control system with a single mode. However, the transients between those modes can introduce steps or overshootings in the state variables, and this can degrade the performance or even damage the control or the plant. So, the smoothing of such transients is vital for their reliability and mantainability. This is can be of extreme importance in the aerospace and automotive fields, plenty of switchings between manual and autopilot modes via relays, or among gears via clutches, for example. In this work, we present a first strategy for smoothing transients in switching controls of aerospace and automotive systems.
2016-10-17
Technical Paper
2016-01-2274
Paul V. Harvath, Shaelah Reidy, Jonathan Byer
Abstract The amount of acidic material in used engine oil is considered an indicator of the remaining useful life of the oil. Total acid number, determined by titration, is the most widely accepted method for determining acidic content but the method is not capable of speciation of individual acids. In this work, high molecular weight residue was isolated from used engine oil by dialysis in heptane. This residue was then analyzed using pyrolysis-comprehensive two dimensional gas chromatography with time-of-flight mass spectrometry. Carboxylic acids from C2-C18 were identified in the samples with acetic acid found to be the most abundant. This identification provides new information that may be used to improve the current acid detection methodologies for used engine oils.
2016-09-27
Technical Paper
2016-01-2087
Hunter O'Folan, Peter B. Zieve
Abstract There is an ever-present risk for the lower ram on a riveting machine to suffer a damaging collision with aircraft parts during automated fastening processes. The risk intensifies when part frame geometry is complex and fastener locations are close to part features. The lower anvil must be led through an obstructive environment, and there is need for crash protection during side-to-side and lowering motion. An additional requirement is stripping bolt collars using the downward motion of the lower ram, which can require as much as 2500 pounds of pulling force. The retention force on the lower anvil would therefore need to be in excess of 2500 pounds. To accomplish this a CNC controlled electromagnetic interface was developed, capable of pulling with 0-3400 pounds. This electromagnetic safety base releases when impact occurs from the sides or during downward motion (5 sided crash protection), and it retains all riveting and bolting functionality.
2016-09-27
Technical Paper
2016-01-2090
Sergey Lupuleac, Margarita Petukhova, Julia Shinder, Alexander Smirnov, Mariia Stefanova, Nadezhda Zaitseva, Tatiana Pogarskaia, Elodie Bonhomme
Abstract The paper is devoted to description of features and functionalities of special software complex aimed at global simulation of junction process using efficient numerical algorithms. The paper presents the concept of developed software and its structure. Types of problems, which the complex is applicable for, are enumerated.
2016-09-27
Technical Paper
2016-01-2097
Sylvain Laporte, Cosme De Castelbajac, Mathieu Ladonne
Abstract The Vibration Assisted Drilling (VAD) process has been implemented in Automated Drilling Equipment (ADE) on an industrial scale since 2011. Today more than 11000 ADEs are currently used on aircraft assembly lines. As well as drawing up a short report on the use of this new process, the authors make an assessment on new challenges that VAD has to face up. Indeed production rates are increasing and ADE manufacturers improve their technologies, one of the most recent and major development concerning the electrical motorization of the machines. These evolutions are as many opportunities for the VAD provided you have a clever understanding as well as an expert knowledge of the process. Thus the authors propose a new dynamic model of the whole VAD system which integrates the behavior of the part, cutting tool/material pair and the machine. The confrontation of model results and experimental validation tests demonstrates the relevance of the works.
2016-09-27
Technical Paper
2016-01-2124
Sara Nilsson, Jonas Jensen, Mats Björkman, Erik Sundin
Abstract Carbon fiber-reinforced plastic (CFRP) is one of the most commonly used materials in the aerospace industry today. CFRP in pre-impregnated form is an anisotropic material whose properties can be controlled to a high level by the designer. Sometimes, these properties make the material hard to predict with regards to how the geometry affects manufacturing aspects. This paper describes eleven design rules originating from different guidelines that describe geometrical design choices and deals with manufacturability problems that are connected to them, why they are connected and how they can be minimized or avoided. Examples of design choices dealt with in the rules include double curvature shapes, assembly of uncured CFRP components and access for non-destructive testing (NDT). To verify the technical content and ensure practicability, the rules were developed by, inter alia, studying literature and performing case studies at SAAB Aerostructures.
2016-09-27
Journal Article
2016-01-2126
Ali Mohamed Abdelhafeez, Sein Leung Soo, David Aspinwall, Anthony Dowson, Dick Arnold
Abstract Despite the increasing use of carbon fibre reinforced plastic (CFRP) composites, titanium and aluminium alloys still constitute a significant proportion of modern civil aircraft structures, which are primarily assembled via mechanical joining techniques. Drilling of fastening holes is therefore a critical operation, which has to meet stringent geometric tolerance and integrity criteria. The paper details the development of a three-dimensional (3D) finite element (FE) model for drilling aerospace grade aluminium (AA7010-T7451 and AA2024-T351) and titanium (Ti-6Al-4V) alloys. The FE simulation employed a Coupled Eulerian Lagrangian (CEL) technique. The cutting tool was modelled according to a Lagrangian formulation in which the mesh follows the material displacement while the workpiece was represented by a non-translating and material deformation independent Eulerian mesh.
2016-09-20
Technical Paper
2016-01-2047
K. Suresh, Rajkumar Dhande, Udupi Ananthakrishna Acharya
Abstract Reducing the amount of physical testing is of importance in the aeronautical industry, where each physical test represents a significant cost. Apart from the cost aspect, it may also be difficult or hazardous to carry out physical testing. Specific to the aeronautic industry are also the relatively long development cycles, implying long periods of uncertainty during product development. In any industry a common viewpoint is that of verification, validation, and uncertainty quantification using simulation models are critical activities for a successful development of a product. In Aeronautical application, the design of store's structural equipments needs to be certified in accordance with MIL-T-7743F [1]. This paper focuses on a case study for shock analysis, whereby an attempt has been made to reduce the cost of certification by way of replacing the actual physical testing by a reliable high fidelity FE simulation.
2016-09-20
Technical Paper
2016-01-1979
William D. Bertelsen
Abstract Technology to create a VTOL for general aviation that is fast, efficient, easy to fly, and affordable, has proven elusive. Bertelsen Design LLC has built a large research model to investigate the potential of the arc wing VTOL to fulfill these attributes. The aircraft that is the subject of this paper weighs approximately 145 kg (320 lbs) and features coaxial, dual-rotating propellers, diameter 1.91 m (75 inches). Power is from an MZ 202 two-cycle, two-cylinder engine. Wingspan is 1.82 m (72 inches). The arc wing differentiates this aircraft from previous deflected-slipstream prototypes, which suffered from pitch-trim issues during transition. This paper will present configuration details of the Bertelsen model, showing how it is possible to generate high lift from a short-span wing system. The Bertelsen model can hover out of ground effect using just two arc-wing elements: a main wing and a “slat”.
2016-09-20
Technical Paper
2016-01-1985
Fei Gao, Serhiy Bozhko, Patrick Wheeler
Abstract The paper will deal with the problem of establishing a desirable power sharing in multi-feed electric power system for future more-electric aircraft (MEA) platforms. The MEA is one of the major trends in modern aerospace engineering aiming for reduction of the overall aircraft weight, operation cost and environmental impact. Electrical systems are employed to replace existing hydraulic, pneumatic and mechanical loads. Hence the onboard installed electrical power increases significantly and this results in challenges in the design of electrical power systems (EPS). One of the key paradigms for future MEA EPS architectures assumes high-voltage dc distribution with multiple sources, possibly of different physical nature, feeding the same bus(es). In our study we investigate control approaches to guarantee that the total electric load is shared between the sources in a desirable manner. A novel communication channel based secondary control method is proposed in this paper.
2016-09-20
Technical Paper
2016-01-1989
Qiong Wang, Rolando Burgos, Xuning Zhang, Dushan Boroyevich, Adam White, Mustansir Kheraluwala
Abstract In modern aircraft power systems, active power converters are promising replacements for transformer rectifier units concerning efficiency and weight. To assess the benefits of active power converters, converter design and optimization should be carefully done under the operation requirements of aircraft applications: electromagnetic interference (EMI) standards, power quality standards, etc. Moreover, certain applications may have strict limits on other converter specifications: weight, size, converter loss, etc. This paper presents the methodology for performance optimization of different active power converters (active front-ends, isolated DC/DC converters and three-phase isolated converters) for aircraft applications. Key methods for power converter component (e.g. inductors, semiconductor devices, etc.) performance optimization and loss calculation are introduced along with the converter optimization procedure.
2016-09-20
Technical Paper
2016-01-1991
Syed J. Khalid
Abstract Aircraft subsystems essential for flight safety and airworthiness, including flight controls, environmental control system (ECS), anti-icing, electricity generation, and starting, require engine bleed and power extraction. Predictions of the resulting impacts on maximum altitude net thrust(>8%), range, and fuel burn, and quantification of turbofan performance sensitivities with compressor bleed, and with both high pressure(HP) rotor power extraction and low pressure(LP) rotor power extraction were obtained from simulation. These sensitivities indicated the judicious extraction options which would result in the least impact. The “No Bleed” system in Boeing 787 was a major step forward toward More Electric Aircraft (MEA) and analysis in this paper substantiates the claimed benefits.
2016-09-20
Technical Paper
2016-01-1994
Wei Wu, Yeong-Ren Lin, Louis Chow, Edmund Gyasi, John P. Kizito, Quinn Leland
Abstract For aircraft electromechanical actuator (EMA) cooling applications using forced air produced by axial fans, the main objective in fan design is to generate high static pressure head, high volumetric flow rate, and high efficiency over a wide operating range of rotational speed (1x∼3x) and ambient pressure (0.2∼1 atm). In this paper, a fan design based on a fan diameter of 86 mm, fan depth (thickness) of 25.4 mm, and hub diameter of 48 mm is presented. The blade setting angle and the chord lengths at the leading and trailing edges are varied in their suitable ranges to determine the optimal blade profiles. The fan static pressure head, volumetric flow rate, and flow velocity are calculated at various ambient pressures and rotational speeds. The optimal blade design in terms of maximum total-to-total pressure ratio and efficiency at the design point is obtained via CFD simulation.
2016-09-20
Technical Paper
2016-01-1997
Wei Wu, Yeong-Ren Lin, Louis Chow, Edmund Gyasi, John P. Kizito, Quinn Leland
Abstract The aircraft electromechanical actuator (EMA) cooling fan is a critical component because an EMA failure caused by overheating could lead to a catastrophic failure in aircraft. Fault tree analysis (FTA) is used to access the failure probability of EMA fans with the goal of improving their mean time to failure (MTTF) from ∼O(5×104) to ∼ O(2.5×109) hours without incurring heavy weight penalty and high cost. The dual-winding and dual-bearing approaches are analyzed and a contra rotating dual-fan design is proposed. Fan motors are assumed to be brushless direct current (BLDC) motors. To have a full understanding of fan reliability, all possible failure mechanisms and failure modes are taken into account.
2016-09-20
Technical Paper
2016-01-1996
David R. Markham, J. Michael Cutbirth
Abstract Modern military electronics systems are generating increasingly higher heat loads, necessitating larger capacity thermal management systems (TMSs). These high-capacity TMSs must meet the strict size and weight requirements of these advancing platforms. Commercially available compressor technology can generate sufficient cooling for these systems; however, they are too heavy and expansive. Mainstream Engineering Corporation has developed a compact, lightweight, high-speed screw compressor that can provide a large cooling capacity with a small package envelope. The compressor housing material is light-weight with a low coefficient of thermal expansion (CTE), allowing a wide operating temperature range. The compressor, with a nominal cooling capacity from 20 kW to 60 kW, was tested over a range of saturated suction conditions, pressure ratios, rotational speeds, and oil lubrication conditions.
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