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Viewing 181 to 210 of 8579
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
2016-01-1999
Debabrata Pal, Frank Feng
Abstract In 3-phase AC application, there is additional heat dissipation due to skin effects and proximity effects in bus bars. In addition, when the 3- phase AC is used to drive a motor at high fundamental frequency, for example between 666 Hz and 1450 Hz, there are higher bus bar losses due to presence of higher frequency harmonic content. High frequency current carrying bus bars in aircraft power panels are typically cooled by natural convection and radiation. In this paper a thermal and electrical finite element analysis (FEA) is done for a bus bar system. For electrical loss modeling, 3D electromagnetic FEA is used to characterize losses in three parallel bus bars carrying AC at various frequencies. This loss analysis provides correlation of heat loss as function of frequency. A method is presented where this AC loss is incorporated using computational fluid dynamics (CFD) based thermal model.
2016-09-20
Technical Paper
2016-01-1998
Michele Trancossi, Jose Pascoa, Carlos Xisto
Abstract Environmental and economic issues related to the aeronautic transport, with particular reference to the high-speed one are opening new perspectives to pulsejets and derived pulse detonation engines. Their importance relates to high thrust to weight ratio and low cost of manufacturing with very low energy efficiency. This papers presents a preliminary evaluation in the direction of a new family of pulsejets which can be coupled with both an air compression system which is currently in pre-patenting study and a more efficient and enduring valve systems with respect to today ones. This new pulsejet has bee specifically studied to reach three objectives: a better thermodynamic efficiency, a substantial reduction of vibrations by a multi-chamber cooled architecture, a much longer operative life by more affordable valves. Another objective of this research connects directly to the possibility of feeding the pulsejet with hydrogen.
2016-09-20
Technical Paper
2016-01-2000
Mark Bodie, Thierry Pamphile, Jon Zumberge, Thomas Baudendistel, Michael Boyd
Abstract As technology for both military and civilian aviation systems mature into a new era, techniques to test and evaluate these systems have become of great interest. To achieve a general understanding as well as save time and cost, the use of computer modeling and simulation for component, subsystem or integrated system testing has become a central part of technology development programs. However, the evolving complexity of the systems being modeled leads to a tremendous increase in the complexity of the developed models. To gain confidence in these models there is a need to evaluate the risk in using those models for decision making. Statistical model validation techniques are used to assess the risk of using a given model in decision making exercises. In this paper, we formulate a transient model validation challenge problem for an air cycle machine (ACM) and present a hardware test bench used to generate experimental data relevant to the model.
2016-09-20
Journal Article
2016-01-2023
Timothy Deppen, Brian Raczkowski, Marco Amrhein, Jason Wells, Eric Walters, Mark Bodie, Soumya Patnaik
Abstract Future aircraft systems are projected to have order of magnitude greater power and thermal demands, along with tighter constraints on the performance of the power and thermal management subsystems. This trend has led to the need for a fully integrated design process where power and thermal systems, and their interactions, are considered simultaneously. To support this new design paradigm, a general framework for codifying and checking specifications and requirements is presented. This framework is domain independent and can be used to translate requirement language into a structured definition that can be quickly queried and applied to simulation and measurement data. It is constructed by generalizing a previously developed power quality analysis framework. The application of this framework is demonstrated through the translation of thermal specifications for airborne electrical equipment, into the SPecification And Requirement Evaluation (SPARE) Tool.
2016-09-20
Journal Article
2016-01-2054
Deniz Unlu, Federico Cappuzzo, Olivier Broca, Pierpaolo Borrelli
Abstract This paper presents the activities foreseen on the Leonardo Aircraft Division EIS (Entry In Service) 2020 derivative aircraft performed in the frame of the FP7 European research project TOICA (Thermal Overall Integrated Concept of Aircraft). On board air systems for conventional aircraft are fed by the bleed off-take which penalizes the amount of power available to the turbine of jet or turboprop engines. In order to minimize such operating penalties and optimize the energy efficiency of the overall aircraft, it is of major interest to support trade-offs at aircraft level including aircraft systems as early as possible in the development cycle. The study presents the Virtual Integrated Aircraft methodology and associated simulation activities relying on the system simulation platform LMS Imagine.Lab. This methodology is also relying on concept of flexible model and pyramid of models developed in the context of TOICA.
2016-09-20
Journal Article
2016-01-1995
Patrick McCarthy, Nicholas Niedbalski, Kevin McCarthy, Eric Walters, Joshua Cory, Soumya Patnaik
Abstract As the cost and complexity of modern aircraft systems increases, emphasis has been placed on model-based design as a means for reducing development cost and optimizing performance. To facilitate this, an appropriate modeling environment is required that allows developers to rapidly explore a wider design space than can cost effectively be considered through hardware construction and testing. This wide design space can then yield solutions that are far more energy efficient than previous generation designs. In addition, non-intuitive cross-coupled subsystem behavior can also be explored to ensure integrated system stability prior to hardware fabrication and testing. In recent years, optimization of control strategies between coupled subsystems has necessitated the understanding of the integrated system dynamics.
2016-09-20
Technical Paper
2016-01-1978
Philippe Coni, Sylvain Hourlier, Xavier Servantie, Laurent Laluque, Aude Gueguen
Abstract A 3D Stereoscopic Head-Up Display (HUD) using direct projection on a transparent screen is presented. Symbol incrustation in conformity with the landscape is performed through the use of simulated collimation offering a large eye-box, in excess of conventional HUD. The use of spectral glasses for our transparent screen was decided as most commonly used polarizing or active glasses were not adapted. Furthermore it gave ususeful green laser attack protection.
2016-09-18
Technical Paper
2016-01-1920
Deaglan O'Meachair, Stamatis Angelinas, Matthew Crumpton, Antonio Rubio Flores, Juan Garcia, Pablo Barles
Abstract Bentley Motors Ltd. has developed a Carbon Silicon Carbide (CSiC) brake system for its Mulsanne product, introduced at 17MY. The CSiC brake system is conceived as a performance brake system, and as such offers notable improvements in brake performance. In developing the brake system, particular focus was placed on meeting the refinement levels required for a premium product, and indeed as the flagship model for Bentley Motors, NVH refinement of the brake system was of particular concern. This paper intends to discuss the technical performance of the brake system and review the NVH performance of the brakes. Particular attention is given to the methodology employed by Bentley Motors Ltd. and IDIADA Automotive Technology S.A. in identifying NVH concerns, and proposing and validating solutions in the field, through extensive NVH endurance runs. The performance of the system is benchmarked against similar systems offered by Bentley Motors.
2016-09-18
Technical Paper
2016-01-1935
Binyu Mei, Xuexun Guo, Gangfeng Tan, Ming Chen, Bo Huang, Longjie Xiao
Abstract With the continuous increasing requirements of commercial vehicle weight and speed on highway transportation, conventional friction brake is difficult to meet the braking performance. To ensure the driving safety of the vehicle in the hilly region, the eddy current retarder (ECR) has been widely used due to its fast response, lower prices and convenient installation. ECR brakes the vehicle through the electromagnetic force generated by the current, and converted vehicle mechanical energy into heat through magnetic field. Air cooling structure is often used in the traditional ECR and cooling performance is limited, which causes low braking torque, thermal recession, and low reliability and so on. The water jacket has been equipped outside the eddy current region in this study, and the electric ECR is cooled through the water circulating in the circuit, which prolongs its working time.
2016-09-18
Technical Paper
2016-01-1941
Tie Wang, Gangfeng Tan, Xuexun Guo, Shengguang Xiong, Zhiwei Zhang, Xin Gao
Abstract Vehicle hydraulic retarders are applied in heavy-duty trucks and buses as an auxiliary braking device. In traditional cooling systems of hydraulic retarders, the working fluid is introduced into the heat exchanger to transfer heat to the cooling liquid in circulation, whose heat is then dissipated by the engine cooling system. This prevents the waste heat of the working fluid from being used effectively. In hydraulic retarder cooling system based on the Organic Rankine Cycle, the organic working fluid first transfers heat with the hydraulic retarder working fluid in Rankine cycle, and then outputs power through expansion machine. It can both reduce heat load of the engine cooling system, and enhance thermal stability of the hydraulic retarder while recovering and utilizing braking energy. First of all, according to the target vehicle model, hydraulic retarder cooling system model based on Rankine cycle is established.
2016-09-18
Journal Article
2016-01-1929
Nimrod Kapas, Ajith Jayasundera
Abstract There is an increasing interest in transient thermal simulations of automotive brake systems. This paper presents a high-fidelity CFD tool for modeling complete braking cycles including both the deceleration and acceleration phases. During braking, this model applies the frictional heat at the interface on the contacting rotor and pad surfaces. Based on the conductive heat fluxes within the surrounding parts, the solver divides the frictional heat into energy fluxes entering the solid volumes of the rotor and the pad. The convective heat transfer between the surfaces of solid parts and the cooling airflow is simulated through conjugate heat transfer, and the discrete ordinates model captures the radiative heat exchange between solid surfaces. It is found that modeling the rotor rotation using the sliding mesh approach provides more realistic results than those obtained with the Multiple Reference Frames method.
2016-06-17
Journal Article
2016-01-9144
Pengfei Zang, Zhe Wang, Chenle Sun
Abstract The linear internal combustion engine-linear generator integrated system (LICELGIS) is an innovative structure as a range-extender for the hybrid vehicles, which contains two opposed free piston engines and one linear generator between them. The LICELGIS is a promising power package due to its high power density and multi-fuel flexibility. In the combustion process of linear engines, the top dead center (TDC) position is not stable in different cycles, which significantly affects system operations. Otherwise, pistons move away from the TDC with high-speed because of the tremendous explosive force, which incurs the short residence time of pistons around the TDC and rapid decrease of in-cylinder temperature, pressure and the combustion efficiency. In order to address this problem, a scientific simulation model which includes dynamic and thermodynamic models, is established and a combustion optimization control strategy is proposed.
2016-06-15
Technical Paper
2016-01-1814
Maxime Legros, Jean Michel Ville, Solène Moreau, Xavier Carniel, Christophe Lambourg, Guillaume Stempfel
Abstract The new requirements during the first stages of the conception of a HVAC prompt the designer to integrate the acoustic problematic increasingly upstream. The designer needs to select a coherent components’ choice in order to comply with the specifications in terms of aeraulic and acoustic performances. A tool has been created to guide the designer’s choices based on an acoustic synthesis which is a design and/or diagnosis approach used to analyze and predict the acoustic behavior of a complex system. The synthesis is developed in order to propose an approach which considers the integration effects and some interaction effects. The acoustic synthesis results are the starting point of a psycho-acoustic study providing audio samples of the prediction and indications of the HVAC acceptance by the prospective user. Also, one may compare the results of different acoustic synthesis projects to study the influence of the parameters on the acoustic prediction.
2016-06-15
Technical Paper
2016-01-1851
Arnaud Duval, Minh Tan Hoang, Valérie Marcel, Ludovic Dejaeger
Abstract The noise treatments weight reduction strategy, which consists in combining broadband absorption and insulation acoustic properties in order to reduce the weight of barriers, depends strongly on surface to volume ratio of the absorbing layers in the reception cavity. Indeed, lightweight technologies like the now classical Absorber /Barrier /Absorber layup are extremely efficient behind the Instrument Panel of a vehicle, but most of the time disappointing when applied as floor insulator behind the carpet. This work aims at showing that a minimum of 20 mm equivalent “shoddy” standard cotton felt absorption is requested for a floor carpet insulator, in order to be able to reduce the weight of barriers. This means that a pure absorbing system that would destroy completely the insulation properties and slopes can only work, if the noise sources are extremely low in this specific area, which is seldom the case even at the rear footwells location.
2016-06-15
Technical Paper
2016-01-1853
Timo Hartmann, Gregor Tanner, Gang Xie, David J. Chappell
Abstract Car floor structures typically contain a number of smaller-scale features which make them challenging for vibro-acoustic modelling beyond the low frequency regime. The floor structure considered here consists of a thin shell floor panel connected to a number of rails through spot welds leading to an interesting multi-scale modelling problem. Structures of this type are arguably best modelled using hybrid methods, where a Statistical Energy Analysis (SEA) description of the larger thin shell regions is combined with a finite element model (FEM) for the stiffer rails. In this way the modal peaks from the stiff regions are included in the overall prediction, which a pure SEA treatment would not capture. However, in the SEA regions, spot welds, geometrically dependent features and directivity of the wave field are all omitted. In this work we present an SEA/FEM hybrid model of a car floor and discuss an alternative model for the SEA subsystem using Discrete Flow Mapping (DFM).
2016-06-15
Technical Paper
2016-01-1800
Xavier Carniel, Anne Sanon
Abstract The control of sound fields radiated by vibrating structures in a passenger compartment, (especially structures connected to different organs like the engine powertrain, the fan motor unit, seats, the steering column, electrical motors more and more, etc.) is among the functions of the automotive manufacturers. The absence of physical prototypes in the development phase systems led OEMs1 to use tests results obtained on benches following technical specifications from manufacturers. The transition "bench to vehicle" for vibro- acoustic behaviour sets many challenges that this standard intends to clear up. This standard specifies the experimental method to transpose the dynamic forces generated by the global movements of an active component between the vehicle and a test bench. The efforts are first measured on test benches and then transposed from test bench towards the vehicle. The standard is now a French standard (XP R 19-701) and is submitted to ISO process [1].
2016-06-15
Technical Paper
2016-01-1780
Francesca Ronzio, Theophane Courtois
Abstract In automotive acoustics, body NVH design is traditionally carried out without considering the acoustic trim parts. Nevertheless, the vibro-acoustic interaction of body structure and insulation trim cannot be neglected in the middle frequency range, where structure borne propagation might still be dominating and where classical statistical approaches are generally not able to represent the influence of local changes in stiffness and damping. This, together with the market requirement of lightweight and more efficient sound package solutions, is leading the CAE engineers to evaluate new design approaches dedicated to vehicle components such as dash or floor systems, for which the multi-physics interaction between damping, body stiffness and trim impedance is important.
2016-06-15
Technical Paper
2016-01-1841
Peter R. Hooper
Powertrain system duplication for hybrid electric vehicles and range-extenders presents serious cost challenges. Cost increase can be mitigated by reducing the number of cylinders but this usually has a negative impact on noise, vibration and harshness (NVH) of the vehicle system. This paper considers a novel form of two-stroke cycle engine offering potential for low emissions, reduced production cost and high potential vehicle efficiency. The engine uses segregated pump charging via the use of stepped pistons offering potential for low emissions. Installation as a power plant for automotive hybrid electric vehicles or as a range-extender for electric vehicles could present a low mass solution addressing the drive for vehicle fleet CO2 reduction. Operation on the two-stroke cycle enables NVH advantages over comparable four-stroke cycle units, however the durability of conventional crankcase scavenged engines can present significant challenges.
2016-06-15
Technical Paper
2016-01-1812
Saad Bennouna, Solène Moreau, Jean Michel Ville, Olivier Cheriaux
Abstract The noise radiated inside the car cabin depends on many sources such as the embedded equipments like the Heating, Ventilation and Air Conditioning (HVAC) module. An HVAC is a compact and complex system composed of several elements: blower, flaps, thermal exchangers, ducts… Air provided by an HVAC is blown by a blower passing through different components and then distributed to car cabin areas. Interactions between airflow and the HVAC fixed components generate noises that emerge in the car cabin. CEVAS project, managed by the automotive equipment manufacturer Valeo, is aiming to develop a prediction tool which will provide HVAC noise spectrum and sound quality data. The tool is based, in particular, on aeroacoustic characterization of individual elements and associations of elements.
2016-06-15
Technical Paper
2016-01-1810
Marie Escouflaire, Nicolas Zerbib, David Mas, Nicolas Papaxanthos, Saad Bennouna, Emmanuel Perrey-Debain, Boureima Ouedraogo, Solène Moreau, Jean Michel Ville
Abstract In the framework of noise reduction of HVAC (Heating, Ventilating and Air Conditioning) systems designed for cars, the present study deals with the numerical prediction of aeroacoustics phenomena encountered inside such devices for industrial purposes, i.e. with a reasonable CPU time. It is then proposed in this paper to assess the validity of the chaining, via Lighthill-Curle analogy, of a DES (Detached Eddy Simulation) resulting from the CFD code OpenFOAM (ESI Group) versus a RANS-LES (Large Eddy Simulation) and a BEM calculation resulting from the Vibro/Aeroacoustics software VA One (ESI Group) on an academic case of air passing through a rectangular diaphragm at a low Mach number. The BEM code being parallelized, the performances of DMP (Distributed Memory Processing) solution will also be assessed.
2016-06-15
Journal Article
2016-01-1778
Gesche Fender, Steffen Marburg, Fabian Duddeck
Abstract One method to lower noise in a cabin is to position damping layers on vibrating panels, thereby reducing their radiated power. To assess the damping effect, criteria like the ERP (equivalent radiated power) are widely employed, which estimate the radiated sound power of a panel without taking into account the actual complex system. Advantageously only a part of the structure has to be modeled, but the optimal solution found on the simplified model then often fails for the complete, coupled system, especially if several variants of a cabin have to be considered. Hence, it is proposed to use the structure-only optimization for identification of a set of candidate solutions for optimal positioning of damping layers. These candidate solutions used as initial designs for the coupled investigations should be well distributed in the design space to avoid being wrongly stuck in an optimum with inferior coupled performance.
2016-06-15
Journal Article
2016-01-1808
Manfred Kaltenbacher, Andreas Hüppe, Aaron Reppenhagen, Matthias Tautz, Stefan Becker, Wolfram Kuehnel
Abstract We present a recently developed computational scheme for the numerical simulation of flow induced sound for rotating systems. Thereby, the flow is computed by scale resolving simulations using an arbitrary mesh interface scheme for connecting rotating and stationary domains. The acoustic field is modeled by a perturbation ansatz resulting in a convective wave equation based on the acoustic scalar potential and the substational time derivative of the incompressible flow pressure as a source term. We use the Finite-Element (FE) method for solving the convective wave equation and apply a Nitsche type mortaring at the interface between rotating and stationary domains. The whole scheme is applied to the numerical computation of a side channel blower.
2016-05-18
Journal Article
2016-01-9110
Jignesh Vaghela
Abstract This study involves the experimental aspects of R134a Automobile Air Conditioning (AAC) system with & without Liquid Suction Heat Exchanger (LSHX). To evaluate the performance of an Automobile Air Conditioning system, an experimental system consisting of original components from an R134a Automobile Air Conditioning system has been set up and instrumented. An additional Liquid Suction Heat Exchanger is used in conventional Automobile Air Conditioning system. Effect of evaporator temperature variation & compressor speed variation on R134a Automobile Air Conditioning system performance is evaluated. From experimental evaluation, it is derived that there is a Coefficient of Performance (COP) improvement in Automobile Air Conditioning system with Liquid Suction Heat Exchanger compared to Automobile Air Conditioning system without Liquid Suction Heat Exchanger. Performance of an R134a Automobile Air Conditioning system degrades with increase in compressor speed.
2016-05-01
Journal Article
2015-01-9148
Saeed Asgari, Shailendra Kaushik
Abstract A linear parameter varying (LPV) reduced order model (ROM) is used to approximate the volume-averaged temperature of battery cells in one of the modules of the battery pack with varying mass flow rate of cooling fluid using uniform heat source as inputs. The ROM runs orders of magnitude faster than the original CFD model. To reduce the time it takes to generate training data, used in building LPV ROM, a divide-and-conquer approach is introduced. This is done by dividing the battery module into a series of mid-cell and end-cell units. A mid-cell unit is composed of a cooling channel sandwiched in between two half -cells. A half-cell has half as much heat capacity as a full-cell. An end-cell unit is composed of a cooling channel sandwiched in between full-cell and a half-cell. A mass flow rate distribution look-up-table is generated from a set of steady-state simulations obtained by running the full CFD model at different inlet manifold mass flow rate samples.
2016-04-05
Technical Paper
2016-01-0008
Johnathan Putrus, Stanley Jones, Badih Jawad, Giscard Kfoury, Selin Arslan, Peter Schihl
Thermal management systems (TMS) of armored ground vehicle designs are often incapable of sustained heat rejection during high tractive effort conditions and ambient conditions. During these conditions, which mainly consist of high torque low speed operations, gear oil temperatures can rise over the allowable 275°F limit in less than twenty minutes. This work outlines an approach to temporarily store excess heat generated by the differential during high tractive effort situations through the use of a passive Phase Change Material (PCM) retrofit thereby extending the operating time, reducing temperature transients, and limiting overheating. A numerical heat transfer model has been developed based on a conceptual vehicle differential TMS. The model predicts the differential fluid temperature response with and without a PCM retrofit. The developed model captures the physics of the phase change processes to predict the transient heat absorption and rejection processes.
2016-04-05
Technical Paper
2016-01-0646
Pablo Olmeda, Jaime Martin, Antonio Garcia, Diego Blanco, Alok Warey, Vicent Domenech
Abstract Regulated emissions and fuel consumption are the main constraints affecting internal combustion engine (ICE) design. Over the years, many techniques have been used with the aim of meeting these limitations. In particular, exhaust gas recirculation (EGR) has proved to be an invaluable solution to reduce NOx emissions in Diesel engines, becoming a widely used technique in production engines. However, its application has a direct effect on fuel consumption due to both the changes in the in-cylinder processes, affecting indicated efficiency, and also on the air management. An analysis, based on the engine Global Energy Balance, is presented to thoroughly assess the behavior of a HSDI Diesel engine under variable EGR conditions at different operating points. The tests have been carried out keeping constant the conditions at the IVC and the combustion centering.
2016-04-05
Technical Paper
2016-01-0647
Azmi Osman, M. Khairul Arif Muhammad Yusof, Mohammad Rafi
Abstract Additional fuel consumption reduction during the NEDC test cycle and real life driving can be effectively achieved by quickly raising the temperatures of the powertrain’s parts, oils and coolant closer to the optimal operating temperatures. In particular, the engine cooling system today must play a bigger role in the overall thermal management of the powertrain’s fluids and metals during warm-up, idle and severe operating conditions. In responding to these additional requirements, the previously proposed cost effective split cooling system has been further evolved to expedite the powertrain’s warming up process without compromising the overall heat rejection performance during severe operating conditions. In achieving these warming and cooling functions, the coolant flow rate in the cylinder head is almost stagnant when the single thermostat is closed and at its maximum when the thermostat is fully opened.
2016-04-05
Technical Paper
2016-01-0657
T Sethuramalingam, Chandrakant Parmar, Sashikant Tiwari
Abstract DFSS is a disciplined problem prevention approach which helps in achieving the most optimum design solution and provides improved and cost effective quality products. This paper presents the implementation of DFSS method to design a distinctive cooling system where engine is mounted in the rear and radiator is mounted in the front of the car. In automobile design, a rear-engine design layout places the engine at the rear of the vehicle. This layout is mainly found in small, entry level cars and light commercial vehicles chosen for three reasons - packaging, traction, and ease of manufacturing. In conventional Passenger cars, a radiator is located close to the engine for simple packaging and efficient thermal management. This paper is about designing a distinctive cooling system of a car having rear mounted engine and front mounted radiator.
2016-04-05
Technical Paper
2016-01-0255
Yinhua Zheng
This paper addresses R1234yf A/C system performance impacted by condenser airflow passage blockages of nonhotspot and hotspot objects. With the modern vehicle design trend, more and more chances exist in blocking condenser airflow passages by objects such as TOC (transmission oil cooler) or fine grills etc. These objects create hotspots and narrowed airflow passages to the condenser and result in A/C performance degradation. It is important to understand the specific area of the condenser which is most impacted by a blockage so this area can be avoided in the design/packaging of front end components. In addition, it is important to understand the magnitude of performance loss associated with the specific areas of blockage. As a result of this understanding, optimal design locations for these blockages (including hotspots and grilles) can be proposed in order to mitigate the impact on A/C cooling performance.
Viewing 181 to 210 of 8579