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Technical Paper
2014-10-13
N. Karthikeyan, Anish Gokhale, Narendra Bansode
In scooters, the Continuously Variable Transmission(CVT) is used to transmit the power from the engine to the wheels. The CVT transmission consists of a two pulleys connected to each other through a belt . The change in the transmission ratio is achieved due to the change in the pulley diameters. A centrifugal clutch is attached to the rear pulley to transmit the power to wheels once the engaging engine speed is reached. The heat is generated due to the belt slippage and the engagement of the centrifugal clutch. Excessive heating may damage the belt ,clutch and deteriorate its performance. The cooling of the belt , pulleys and the clutch is thus important for its safe operation. The cooling is achieved by the centrifugal cooling fan which forces the air over the belt, pulley and clutch. A clear understanding of the cooling system is important in designing the air flow path for clutch cooling of CVT housing. The efficiency of the cooling system depends on the quantity and direction of flow .
Technical Paper
2014-10-13
Dhaminda Hewavitarane, Sadami Yoshiyama, Hisashi Wadahama, Xin Li
In our modern industrial civilization, the vast majority of mechanical work is produced by heat engines. While the efficiency of heat engines has improved over the years, they remain relatively inefficient, losing a significant portion of the input heat as waste heat. Waste heat recovery as a means of improving the overall efficiency of these engines in automotive applications has gained momentum in recent years. While many waste heat recovery (W.H.R) systems have been proposed and tested, the balance between, their efficiency, package size, the ease of being integrated to the drivetrain and most importantly cost, have made most nonviable. This paper introduces an alternative heat engine capable of harnessing waste heat, particularly for automotive applications. Theory: High temperature liquids held in a subcooled state are capable of storing energy and then explosively releasing this energy when depressurized, in a phase change process known as "Flashing". The rapid volume expansion that results from the flashing of superheated liquids to vapour has been harnessed to drive an expansion engine working on a cycle similar to the Rankine Cycle.
Technical Paper
2014-09-16
Daniel Schlabe, Jens Lienig
The reduction of aircraft weight, fuel consumption, and hence CO2 emissions is a major goal of future aircraft designs. Efficient and light aircraft systems can considerably contribute to this target which, amongst others, has led to the development of More Electric Aircraft (MEA) in the past. Due to the increased demand of electrical power and the reduced usage or even totally absence of bleed air from the engines, novel types of cooling technologies and hence thermal management systems have been considered. Thermal Management Architectures (TMA) encompass air cycle machines, ram air channels, circulation and distribution of air flow, vapor compression cycles, cooling loops, as well as alternative heat sinks like skin heat exchangers. Together with highly integrated and complex TMAs, there is an increased degree of freedom in controlling the system. Optimal controller signals provided by a Thermal Management Function (TMF) are essential to improve system efficiency and to reduce system weight.
Technical Paper
2014-09-16
Gene Tu, Wei Shih, Walter Yuen
Abstract To meet pulse power mode component cooling application needs, we developed, fabricated and tested a concept to use energy storage material and phase change material to enhance the heat dissipation of a conventional heat sink. Test results demonstrated the ESM/PCM heat sink has unique thermal performance. Under the same working condition, the peak temperature of ESM/PCM heat sink is 1.5°C lower than of a conventional heat sink. An optimized design can lead to a significant weight reduction for the heat sink in applications with high peak load and low duty power cycle power.
Technical Paper
2014-09-16
Fan Frank Wang
Meeting Challenges of Using COTS Component Thermal Data in Aerospace Application Frank Fan Wang Crane Aerospace & Electronics Lynnwood, WA 98046, USA 425-743-8478 frank.wang@crane-eg.com Extended Abstract This article is about the issue of published thermal data from commercial off the shelf (COTS) component manufacturer. Use of commercial electronic components for aerospace applications has the benefit of technical advancement, cost reduction and scheduling. Effectively using commercial electronic components will enhance the performance of aerospace products. In most cases, the benefits of using commercial components can be concluded in three words: cheaper, better, and faster. However, some of the published electrical component thermal data can be confusing and misleading. Use without thorough understanding is risky. The thermal related information from the COTS component datasheets is one of the major issues that has troubled many aerospace electronics equipment packaging engineers for years.
Technical Paper
2014-09-16
Noriko Morioka, Hidefumi Saito, Norio Takahashi, Manabu Seta, Hitoshi Oyori
Abstract Electrical power management is a key technology in the AEA (All-Electric Aircraft) system, which manages the supply and demand of the electrical power in the entire aircraft system. However, the AEA system requires more than electrical power management alone. Adequate thermal management is also required, because the heat generated by aircraft systems and components increases with progressive system electrification, despite limited heat-sink capability in the aircraft. Since heat dissipation from power electronics such as electric motors, motor controllers and rectifiers, which are widely introduced into the AEA, becomes a key issue, an efficient cooling system architecture should be considered along with the AEA system concept. The more-electric architecture for the aircraft has been developed; mainly targeting reduced fuel burn and CO2 emissions from the aircraft, as well as leveraging ease of maintenance with electric/electronic components. The AEA should pursue more efficient and eco-friendlier systems, which are easier to maintain than those of conventional aircraft/MEA (More-Electric Aircraft), to enhance benefits for passengers and operators.
Technical Paper
2014-09-16
Wei Wu, Yeong-Ren Lin, Louis C. Chow, Quinn Leland
W. Wu1, Y.R. Lin1, D. Zhao1, L.C. Chow1 and Q. Leland2 1 Department of Mechanical and Aerospace Engineering, University of Central Florida Orlando, FL 32816 2 Air Force Research Laboratory, Aerospace Systems Directorate Wright Patterson AFB, OH 45433 Background and Purpose The scaling laws of fans express basic relationships among the variables of volume flow rate, air density, rotational speed, fan diameter, and power. This makes it possible to compare the performance of geometrically similar fans in dissimilar conditions. The fan laws were derived from dimensionless analysis of the equations for volumetric flow rate, static pressure head, and power. The purpose of this study is to characterize a fan's performance characteristics at various rotational speeds and various ambient pressures, from 1 atm to 0.2 atm. The experimental results are compared to the fan scaling laws. Methodology A commercial brushless DC axial fan is chosen. It is run within a closed test loop. For various chosen ambient pressures and rotational speeds, the fan static pressure head, volumetric flow rate, and flow velocity were measured.
Technical Paper
2014-09-16
Jesse Miller, John Hoke, Frederick Schauer
An intercooler is a heat exchanger used to lower the temperature of compressed air exiting a turbocharger before entering the engine. Having an effective and reliable intercooler helps avoid engine knock while increasing engine power. An intercooler that does not transfer heat effectively or evenly, and has a high pressure drop causes inefficiencies and can damage the engine. This experiment tests two compact intercoolers designed for a small, high performance, knock limited engine. Both intercoolers use air-to-liquid cross flow heat exchangers with staggered fins. The intercoolers have one air entrance and four air exits as well as a water inlet and outlet. One intercooler uses internal baffles to help evenly distribute airflow. Two different setups are used to test the intercooler at steady versus unsteady airflow conditions. The first setup connects the four air outlets of the intercooler to a common restricted exit creating a constant back pressure which allows for steady airflow.
Technical Paper
2014-09-16
Stephen Emo, Jamie Ervin, Travis E. Michalak, Victor Tsao
Numerous previous studies have highlighted the potential efficiency improvements which can be provided to aircraft thermal management systems by the incorporation of vapor cycle systems (VCS), either in place of, or in conjunction with, standard air cycle systems, for providing the needed refrigeration effect for cooling of aircraft equipment and crews. This paper will present the results of a cycle-based VCS control architecture as tested using the Vapor Cycle System Research Facility (VCSRF) in the Aerospace Systems Directorate of the Air Force Research Laboratory at Wright-Patterson Air Force Base. The VCSRF is a flexible, dynamic, multi-evaporator VCS which incorporates electronic expansion valves and a variable speed compressor to improve the flexibility of the control schemes that can be tested. This facility was designed and fabricated to allow testing of various VCS components and control schemes with the goal of reducing the risk of incorporating VCS into the thermal management systems of future advanced aircraft.
Technical Paper
2014-09-16
Pedro Del valle, Pablo Blazquez Munoz
Advance thermal systems are being developed to optimise the energy balance within aircraft. This is being done in parallel to the concept of the More Electrical Aircraft (MEA) which has been developing throughout the last decades. The objective of such complex systems is to use efficiently the hot and cold sources available within the air vehicle to reduce the engine fuel consumption. A reduction of electrical power consumption, minimisation of weight, optimisation of aircraft aerodynamics (for example RAM inlets area minimisation) and the reduction of bleed air from engine all result in a fuel consumption saving. Any thermal management system to optimise energy consumption implies complex and advanced systems. These require a high engineering effort to be designed and integrated within an aircraft due to the large quantity of variables and interfaces that need to be taken into account. Models and simulations are essential from the beginning of the system development and design phase.
Technical Paper
2014-09-16
Mark Donovan, Pedro Del valle
As aviation enters the future, new technologies and philosophies are required to keep up with ever changing demands and increased market competition. Aircraft designers are required to come up with new and innovative ways to optimise systems and improve efficiencies. Onboard thermal management is an area that can take advantage of several new technologies to do just that. This paper is based on the development project “Advanced Thermal Management in Aeronautics” (ATMIA). Project ATMIA focuses on the use of Loop Heat Pipes (LHPs) in the aeronautical industry, specifically their onboard feasibility and the unique requirements found on an aeronautical platform such as those due to vibrations, gravitational forces and the need for disassembly due to maintenance. LHPs are passive two-phase devices that allow free-energy heat transportation between certain subsystems without needing additional power consumption. Their use in aeronautics is interesting as they can passively transport seemingly “waste” heat to areas where it can be reused.
Technical Paper
2014-09-16
Michael Ellis, William Anderson, Jared Montgomery
Under a program funded by the Air Force Research Laboratory (AFRL), Advanced Cooling Technologies, Inc. (ACT) has developed a series of passive thermal management techniques for cooling avionics. Many avionics packages are often exposed to environment temperatures much higher than the maximum allowable temperatures of the electronics. This condition prevents the rejection of waste heat generated by these electronics to the surrounding environment and results in significant ambient heat gain. As a result, heat must be transported to a remote sink. However, sink selection aboard modern aircraft is limited at best. Often, the only viable sink is aircraft fuel and, depending on mission profile, the fuel temperature can become too high to effectively cool avionics. As a result, the electronic components must operate at higher than intended temperatures during portions of the mission profile, which reduces component lifetime and significantly increases the probability of failure. To address this issue, ACT developed two passive thermal management approaches for avionics packages: heat pipe assemblies to reduce the internal temperature gradient and a Loop Heat Pipe (LHP) to transport thermal energy to alternative sinks.
Technical Paper
2014-09-16
Andrew Slippey, Michael Ellis, Bruce Conway, Hyo Chang Yun
Carbon fiber reinforced polymer (CFRP) composite material is a highly attractive structural material in applications where mass is critical. The carbon fiber matrix provides strength comparable to steel in a material with only about 25% of the density. In many instances, the CFRP sheet can also be made thinner than a metal sheet with similar mechanical properties, further increasing the mass savings. However, thermal challenges have arisen with the increased use of composites in applications where excess heat is being generated internally. In the area of electronics enclosures, traditional metal structures conduct and spread heat out over large external surfaces, but composites have poor thermal conductivity and act as insulators. The heat generated by components causes internal temperatures rise and has detrimental impact on the performance and reliability of the electronics. CFRP materials typically have thermal conductivities on the order of 5 W/m-K, while carbon steel is near 50 W/m-K and aluminum is near 200 W/m-K.
Technical Paper
2014-09-16
James H. Graham, Roger Dixon, Peter Hubbard, Ian Harrington
On future UAVs it is envisaged that the power requirements of all on-board electrical systems will increase. In most flight (mission) situations the installed power generation will have adequate capacity to operate the aircraft. It is possible that during abnormal situations the generators on-board may be forced to operate under very high load conditions. The main failure mechanism for a generator is overheating and subsequent disintegration of windings, hence the research problem being addressed here is to manage the loads upon the generator to prevent overheat. The research presented here summarises the modelling of the generator and formation of the load management system. Results are presented showing the system reallocating loads after a fault during flight, preventing overheat of the generators and successfully completing the mission.
Technical Paper
2014-09-16
Philip Abolmoali, Javier A. Parrilla, Awatef Hamed
Abstract The optimal integration of vehicle subsystems is of critical importance in the design of future energy efficient fighter aircraft. The INVENT (INtegrated Vehicle ENergy Technology) program has been dedicated to this endeavor through modeling/simulation of thermal management, power generation & distribution, & actuation subsystems. Achieving dual cooling & power generation capability from a single subsystem would be consistent with current efforts in system integration optimization. In this paper, we present a reconfiguration of an archetypal closed-loop air cycle system for a modern fighter as an open-loop gas generator cycle operating interchangeably between refrigeration and auxiliary power modes. A numerical model was developed within NPSS to assess maximum power extraction capabilities of a system originally designed for cooling purposes under different operating conditions. Presented results demonstrate variations in maximum power extraction, flow rates, and turbomachinery performance parameters over a range of flight altitudes and Mach numbers.
Technical Paper
2014-09-16
Matthew Dooley, NIcholas Lui, Robb Newman, Clarence Lui
Complex, high-powered electronics used on modern aircraft generate large amounts of heat, and the complexity and energy demands only grow with each new generation of electronics. Commensurate heats sink capable of absorbing this load are the crucial element in an aircraft’s thermal management system, and so the capacities of heat sinks must evolve with this electronics growth. This paper presents an industry survey of conventional heat sinks in current use and then introduces and discusses potential advances in heat sink technologies. These technologies show significant promise to increase the capacity of thermal management systems on future aircraft and thereby unlock the full performance of next generation electronics.
Technical Paper
2014-09-16
Alireza R. Behbahani, Alex Von Moll, Robert Zeller, James Ordo
Abstract Modern propulsion system designers face challenges that require that aircraft and engine manufacturers improve performance as well as reduce the life-cycle cost (LCC). These improvements will require a more efficient, more reliable, and more advanced propulsion system. The concept of smart components is built around actively controlling the engine and the aircraft to operate optimally. Usage of smart components intelligently increases efficiency and system safety throughout the flight envelope, all while meeting environmental challenges. This approach requires an integration and optimization, both at the local level and the system level, to reduce cost. Interactions between the various subsystems must be understood through the use of modeling and simulation. This is accomplished by starting with individual subsystem models and combining them into a complete system model. Hierarchical, decentralized control reduces cost and risk by enabling integration and modularity. This process involves defining, developing, and validating against requirements for key integrated propulsion, power, and thermal management system capabilities.
Technical Paper
2014-09-16
Wei Wu, Yeong-Ren Lin, Louis Chow
Abstract In this paper, we address the thermal management issues which limit the lifespan, specific power and overall efficiency of an air-cooled rotary Wankel engine used in Unmanned Air Vehicles (UAVs). Our goal is to eliminate the hot spots and reduce the temperature gradients in the engine housing and side plates by aggressive heat spreading using heat pipes. We demonstrate by simulation that, for a specific power requirement, with heat spreading and more effective heat dissipation, thermal stress and distortion can be significantly reduced, even with air cooling. The maximum temperature drop was substantial, from 231°C to 129°C. The temperature difference (measure of temperature uniformity) decreased by 8.8 times (from 159°C to 18°C) for a typical UAV engine. Our heat spreaders would not change the frontal area of the engine and should have a negligible impact on the installed weight of the propulsion assembly. We expect our approach could lead to a very significant reduction in thermal stress-induced warping which is primarily responsible for wear and high friction.
Technical Paper
2014-09-16
Matthew R. Cerny, Keith Joerger
This paper identifies critical and relevant variable/adaptive cycle turbine engine and propulsion subsystem technologies for future carrier-based naval aviation systems. A comprehensive evaluation of key technology drivers associated with the development and demonstration of advanced Adaptive Power and Thermal Management System (APTMS) technologies applicable to 6th Generation (Gen) DEW-capable platforms is addressed. Specifically, the paper explores energy optimization through dynamic mission based simulations of an advanced hybrid air cycle / vapor cycle APTMS architecture combining multiple traditionally federated subsystem functions including auxiliary power, environmental control, emergency power, and engine start. The Integrated Power Turbomachine (IPTM) under development by GE Aviation (GEA) is a critical component of the 6th Gen hybrid APTMS architecture, enabling a three-fold increase in design cooling capacity compared to current 5th Gen air dominance platforms, with a significant reduction in engine bleed extraction.
Technical Paper
2014-09-16
Shweta Sanjeev, Goutham Selvaraj, Patrick Franks, Kaushik Rajashekara
Abstract The transition towards More Electric Aircraft (MEA) architectures has challenges relating to integration of power electronics with the starter generator system for on-engine application. To efficiently operate the power electronics in the hostile engine environment at high switching frequency and for better thermal management, use of silicon carbide (SiC) power devices for a bi-directional power converter is examined. In this paper, development of a 50 kVA bi-directional converter operating at an ambient temperature of about 2000C is presented. The design and operation of the converter with details of control algorithm implementation and cooling chamber design are also discussed.
Technical Paper
2014-09-16
David Gras, Christophe Pautrel, Amir Fanaei, Gregory Thepaut, Maxime Chabert, Fabien Laplace, Gonzalo Picun
Abstract In this paper we present a set of integrated circuits specifically designed for high temperature power applications such as isolated power transistor drivers and high efficiency power supplies. The XTR26010 is the key circuit for the isolated power gate drive application. The XTR26010 circuit has been designed with a high focus in offering a robust, reliable and efficient solution for driving a large variety of high-temperature, high-voltage, and high-efficiency power transistors (SiC, GaN, Si) existing in the market. The XTR40010 is used for isolated data communication between a microcontroller or a PWM controller and the power driver (XTR26010). The isolated power transistor driver features a dual turn-on channel, a turn-off channel and a Miller Clamp channel with more than 3A peak current drive strength for each channel. The dV/dt immunity between XTR26010 and XTR40010 exceeds 50kV/μs. To demonstrate the performance and reliability at system level, a half-bridge driver test-board has been developed for driving SiC MOSFETs.
Technical Paper
2014-09-16
Michael L. Zierolf, Thomas Brinson, Andrew Fleming
Abstract Recent emphasis on optimization of engine technologies with ancillary subsystems such as power and thermal management has created a need for integrated system modeling. These systems are coupled such that federated design methods may not lead to the most synergetic solution. Obtaining an optimal design is often contingent on developing an integrated model. Integrated models, however, can involve combining complex simulation platforms into a single system of systems, which can present many challenges. Model organization and configuration control become increasingly important when orchestrating various models into a single simulation. Additionally, it is important to understand such details as the interface between models and signal routing to ensure the integrated behavior is not contaminated or biased. This paper will present some key learnings for model integration to help alleviate some of the challenges with system-based modeling.
Standard
2014-08-28
This SAE Recommended Practice is intended for use in testing and evaluating the performance of Light Duty automotive electric engine cooling fans. These Electric Cooling Fan (ECF) Assemblies are purchased by Light Duty Truck and Passenger Car OEM’s from suppliers. They are purchased as complete assemblies, consisting of the fan(s), motor(s), and shroud (see Figure 1); this Recommended Practice will only consider such complete assemblies. Some purchased assemblies using brush-type motors may also include control devices such as power resistors or pulse width modulation (PWM) electronics for speed control. In the case of brushless motor technology, the controller is an integral part of the motor where it also performs the commutation process electronically. The performance measurement would include fan output in terms of airflow and pressure, and fan input electric power in terms of voltage and current. This information could then be used to calculate the efficiency of the assembly, including aerodynamic efficiency of the fan and shroud and electrical efficiency of the motor.
WIP Standard
2014-08-06
This standard provides the testing and functional requirements guidance necessary for a leak detection device that uses any non-A/C refrigerant tracer gas, such as helium or a nitrogen-hydrogen blend, to provide functional performance equivalent to a refrigerant electronic leak detector. It explains how a non- refrigerant leak detector’s calibration can be established to provide levels of detection equal to electronic leak detectors that meet SAE J2791 for R-134a and SAE J2913 for R-1234yf.
Standard
2014-07-24
This SAE Recommended Practice applies to the use of generally available leak detection methods to service motor vehicle passenger compartment air conditioning systems.
Standard
2014-07-01
This SAE Aerospace Information Report (AIR) provides Nuclear, Biological and Chemical (NBC) protection considerations for environmental control system (ECS) design. It is intended to familiarize the ECS designer with the subject in order to know what information will be required to do an ECS design where NBC protection is a requirement. This is not intended to be a thorough discussion of NBC protection. Such a document would be large and would be classified. Topics of NBC protection that are more pertinent to the ECS designer are discussed in more detail. Those of peripheral interest, but of which the ECS designer should be aware are briefly discussed. Only radiological aspects of nuclear blast are discussed. The term CBR (Chemical, Biological, and Radiological) has been used to contrast with NBC to indicate that only the radiological aspects of a nuclear blast are being discussed. This is actually a more accurate term to describe the subject of this paper, but NBC has become more widely used in the aircraft industry.
Technical Paper
2014-06-30
Alessandro Zanon, Michele De Gennaro, Helmut Kuehnelt, Domenico Caridi, Daniel Langmayr
Abstract In hybrid and electrical vehicles new challenges in meeting the drivers' expectation with regards to acoustic comfort arise. The absence of the internal combustion engine noise enhances the passengers' perception of other noise sources, such as the Heating, Ventilation and Air-Conditioning (HVAC) system. Therefore efficient and reliable numerical models able to predict flow-induced broadband noise have become a major research topic in automotive industry. In this framework, the Zonal LES coupled with the Ffowcs Williams-Hawkings (FWH) acoustic analogy are capable to simulate broadband noise from low speed axial fan. As demonstrated in previous works from the authors, this approach is able to cope with the complexity of the physical phenomena involved (i.e. turbulent noise generation, laminar-to-turbulent transition, etc.), even though the numerical model requires a careful setup of the mesh topology, boundary conditions and simulation parameters. The aim of this article is to provide the scientific community with the latest developments of our research work on numerical modelling of broadband noise from axial fans, focusing on the performance of two different mesh topologies to locate and estimate the noise sources.
WIP Standard
2014-05-12
This SAE Recommended Practice is applicable to all liquid-to-air, liquid-to-liquid, air-to-liquid, and air-to-air heat exchangers used in vehicle and industrial cooling systems. This document outlines the tests to determine durability characteristics of the heat exchanger under thermal cycling. This document is to provide a test guideline for determining the durability of a heat exchanger under thermal cycle conditions.
Technical Paper
2014-05-10
Robert E Smith, Edward Lumsdaine
Since transient vehicle HVAC computational fluids (CFD) simulations take too long to solve in a production environment, the goal of this project is to automatically create a lumped-parameter flow network from a steady-state CFD that solves nearly instantaneously. The data mining algorithm k-means is implemented to automatically discover flow features and form the network (a reduced order model). The lumped-parameter network is implemented in the commercial thermal solver MuSES to then run as a fully transient simulation. Using this network a “localized heat transfer coefficient” is shown to be an improvement over existing techniques. Also, it was found that the use of the clustering created a new flow visualization technique. Finally, fixing clusters near equipment newly demonstrates a capability to track localized temperatures near specific objects (such as equipment in vehicles).
WIP Standard
2014-04-30
This SAE Recommended Practice is applicable to all liquid-to-gas, liquid-to-liquid, gas-to-gas, and gas-to-liquid heat exchangers used in vehicle and industrial cooling systems. This document outlines the test to determine durability characteristics of the heat exchanger from vibration-induced loading.
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