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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
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
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
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
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
Gene Tu, Wei Shih, Walter Yuen
In electronic systems, a heat sink is a necessary passive heat exchanger that cools a device by dissipating heat into the surrounding medium. For example, in computers, heat sinks are used to cool central processing units or graphics processors. Heat sinks are used with high-power semiconductor devices such as power transistors and optoelectronics such as lasers and light emitting diodes (LEDs), where the heat dissipation ability of the basic device is insufficient to moderate its temperature. A heat sink is designed to maximize its surface area in contact with the cooling medium surrounding it, such as the air. Air velocity, choice of material, protrusion design and surface treatment are factors that affect the performance of a heat sink. Currently, relatively simple design methods are available for the design of conventional heat sink, determining the needed thermal resistance, material, fin efficiency for a specific heat duty. For practical applications, heat sinks are generally designed based on peak duty.
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
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
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 efficiency. 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) and continues the analysis of the previous papers. 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 aircrafts have areas that produce excess heat that needs to be rejected and areas that require heat.
Technical Paper
2014-09-16
Philip Abolmoali, Javier A. Parrilla, Awatef Hamed
The optimal integration of vehicle subsystems is of critical importance in the design of future energy efficient fighter aircraft, characterized by megawatt-class thermal loads & power requirements1. The INVENT (INtegrated Vehicle ENergy Technology) program has been dedicated to this endeavor by modeling/simulation and optimization of thermal management, power generation & distribution, & actuation subsystems. Of these subsystems, the Thermal Management System (TMS) is responsible for supporting air & liquid-based cooling for avionics, cockpit, and miscellaneous thermal loads.. Electric power generation & distribution is provided by the Robust Electric Power System (REPS). Both subsystems operate in a highly complex, integrated environment. A reduction in overall system complexity by leveraging components from connected subsystems would be consistent with the spirit of intelligent systems integration and progress the state-of-the-art. In this paper, we present a reconfiguration of an archetypal closed-loop air cycle system for a modern fighter as an open-loop Brayton cycle gas generator that may operate interchangeably between refrigeration and auxiliary power modes.
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
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
Andre Hessling
Abstract Advanced technologies in LED's have the potential to reduce maintenance and improve aircraft safety. Aircrafts need adequate illumination for night time landing. New technology such as high-power LEDs allow for better suited light distributions, more whitish light compatible for mesopic lighting conditions and reduced glare in adverse weather conditions. LEDs and the associated electronics are more susceptible to harsh environmental conditions and this needs to be accounted for in the design of the equipment. Highly conductive metal core PCBs (MCPCB) allow for adequate cooling in a mirror telescopic optical arrangement when coupled with robust active cooling. Closed loop optical feedback of output flux ensures constant performance over the lifetime of the light unit and allows for indication of remaining useful life to the operator to plan maintenance activities. Parylene coating inhibits premature degradation of the LEDs induced by water vapor and corrosive gases.
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
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
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
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.
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.
Article
2014-08-28
Visteon Corp. claims its in-car wireless device charging system is an industry first in that it complies with both of the main standards: Power Matters Alliance (PMA)/Powermat and Wireless Power Consortium (WPC)/Qi. 
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.
Article
2014-08-27
With the recent publishing of four technical reports, SAE International now offers a series of recommended practices designed to enhance overall ambulance safety in several areas, including patient compartments and occupant restraint.
WIP Standard
2014-08-26
This SAE Aerospace Information Report (AIR) describes two classes of lubricants which, when properly applied, can be used in oxygen systems and components.
Magazine
2014-08-22
SMACing the automotive industry: from concept to consumer Technology is making a more significant impact on today's auto industry. Perhaps one of the most notable examples is the development of connected technologies coupled with social, mobile, analytics, and cloud (SMAC) technologies. The 3i paradigm: India's story The concept of ideation, incubation, and implementation is enhancing the growth of the Indian automotive industry. Virtualization for automotive IVI systems As the demand for modern in-vehicle infotainment systems grows, automakers are increasingly looking toward virtualization as a solution to bridge the gap between consumer and automotive electronics. Command Center: Securing connected cars of the future automotive An architectural approach to minimize connectivity interfaces acts as a secure, intelligent gateway between the car and external devices/networks to better guard against malicious or sensitive data from being compromised.
Article
2014-08-20
Redstone Defense Systems selected Northrop Grumman Corp. to supply and integrate mission avionics equipment for a digital cockpit upgrade of the U.S. Army's UH-60L Black Hawk helicopters. Northrop Grumman will provide a scalable, fully integrated mission equipment package for the UH‑60L cockpit and will replace the older analog gauges with digital electronic instrument displays.
WIP Standard
2014-08-20
This document describes the CAD model data available from SAE for the two-dimensional H-point template (HPM-1).
Article
2014-08-12
AC17 test reporting begins in 2015. Initially it "gifts" applicable CAFE A/C efficiency credits, but leads to mandatory use. Industry also looks to reduce A/C-induced EV range loss from solar loading using films, glass, pre-ventilation.
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