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A Passive Solution to Differential Transient Cooling Issues Using Phase Change Materials

US Army TACOM-Peter Schihl
Lawrence Technological University-Badih Jawad, Giscard Kfoury, Selin Arslan
Published 2016-04-05 by SAE International in United States
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. It will be used to evaluate the effectiveness of proposed candidate implementations and provide input for TMS evaluations.Parametric studies of the heat transfer model have been conducted to establish desirable structural morphologies and PCM thermophysical properties.…
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Experimental Validation and Combustion Modeling of a JP-8 Surrogate in a Single Cylinder Diesel Engine

SAE International Journal of Fuels and Lubricants

US Army TACOM-Eric Sattler, Peter Schihl
Wayne State Univ.-Amit Shrestha, Umashankar Joshi, Ziliang Zheng, Tamer Badawy, Naeim Henein
  • Journal Article
  • 2014-01-1376
Published 2014-04-01 by SAE International in United States
This paper presents the results of an experimental investigation on a single cylinder engine to validate a two-component JP-8 surrogate. The two-component surrogate was chosen based on a previous investigation where the key properties, such as DCN, volatility, density, and lower heating value, of the surrogate were matched with those of the target JP-8.The matching of the auto-ignition, combustion, and emission characteristics of the surrogate with JP-8 was investigated in an actual diesel engine environment. The engine tests for the validation of the surrogate were conducted at an engine speed of 1500 rpm, a load of 3 bar, and different injection timings. The results for the cylinder gas pressure, ignition delay period, rate of heat release, and the CO, HC, and NOx emissions showed a good match between the surrogate and the target JP-8. However, the engine-out particulate matter for the surrogate was lower than that for the JP-8 at all tested conditions. These findings are presented and discussed in the paper.Additionally, a reduced surrogate fuel model was constructed and was implemented in three-dimensional CFD…
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Role of Volatility in the Development of JP-8 Surrogates for Diesel Engine Application

SAE International Journal of Fuels and Lubricants

US Army TACOM-Eric Sattler
Wayne State Univ.-Ziliang Zheng, PO-I Lee, Amit Shrestha, Tamer Badawy, Ming-Chia Lai, Naeim Henein
  • Journal Article
  • 2014-01-1389
Published 2014-04-01 by SAE International in United States
Surrogates for JP-8 have been developed in the high temperature gas phase environment of gas turbines. In diesel engines, the fuel is introduced in the liquid phase where volatility plays a major role in the formation of the combustible mixture and autoignition reactions that occur at relatively lower temperatures. In this paper, the role of volatility on the combustion of JP-8 and five different surrogate fuels was investigated in the constant volume combustion chamber of the Ignition Quality Tester (IQT). IQT is used to determine the derived cetane number (DCN) of diesel engine fuels according to ASTM D6890. The surrogate fuels were formulated such that their DCNs matched that of JP-8, but with different volatilities. Tests were conducted to investigate the effect of volatility on the autoignition and combustion characteristics of the surrogates using a detailed analysis of the rate of heat release immediately after the start of injection. In addition, the effect of volatility on the spray dynamics was investigated by Schlieren imaging in an optically accessible rapid compression machine (RCM). The images supported…
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Effect of Intake Pressure and Temperature on the Auto-Ignition of Fuels with Different Cetane Number and Volatility

US Army TACOM-Eric Sattler
Wayne State University-Chandrasekharan Jayakumar, Ziliang Zheng, Umashankar Joshi, Walter Bryzik, Naeim Henein
Published 2012-04-16 by SAE International in United States
This paper investigates the effect of boost pressure and intake temperature on the auto-ignition of fuels with a wide range of properties. The fuels used in this investigation are ULSD (CN 45), FT-SPK (CN 61) and two blends of JP-8 (with CN 25 and 49). Detailed analysis of in-cylinder pressure and rate of heat release traces are made to correlate the effect of intake pressure and injection strategy on the events immediately following start of injection leading to combustion. A CFD model is applied to track the effect of intake pressure and injection strategy on the formation of different chemical species and study their role and contribution in the auto-ignition reactions. Results from a previous investigation on the effect of intake temperature on auto-ignition of these fuels are compared with the results of this investigation.
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Advanced Diesel Engine 42% Brake Thermal Efficiency Technology Demonstrators

US Army TACOM-Milad H. Mekari
Advanced Engines Development Corp.-Nicholas R. Hirsch
Published 2011-04-12 by SAE International in United States
Battlefield delivered fuel (jet and diesel) with required security, storage, transport, and dispensing equipment is estimated to cost $418/gallon [ 1 ], thus the need for very fuel efficient light weight engines for repower and future vehicles is critical. The U.S. Army RDECOM TARDEC Small Business Innovative Research (SBIR) Program funded Advanced Engines Development Corporation (AED) for the exploration, development and application of advanced diesel engine technologies and to incorporate these technologies into demonstrator engines, a 4-cylinder and V-8's. AED based these demonstrators on current production GM gasoline engine diesel conversions employing commercial-off-the-shelf (COTS) advanced diesel systems and engine components. Using an iterative process of analysis, design, fabrication, and dyno testing a 2.2/2.4 liter displacement and 6.5 liter engines incorporating the latest technology in: high pressure common-rail fuel injection; high combustion charge air density utilizing a supercharger and turbocharger in-series with inter- and after-cooling; and a highly turbulent combustion system were developed. A series of three increasingly advanced 2.2/2.4 liter diesel engines were built and dyno tested. All engine systems and operations were electronically managed…
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Mathematical Modeling Software Series of Vehicle Propulsion System Vehicle Road Wheel/Sprocket Tractive Effort

US Army TACOM-Bashir Mekari
TACOM/RDECOM/TARDEC/GVPM/Engine Research-Milad H. Mekari
Published 2010-10-05 by SAE International in United States
To overcome a vehicle's tractive resistances and accelerate its gross weight, the propulsion system must have enough energy available at the diameter of its traction road wheel/sprocket-track as tractive effort. The tractive effort of the wheel/sprocket must balance or exceed that of vehicle's tractive resistances. The tractive resistances are comprised of wheel-terrain rolling friction, also called rolling resistance, R R , ambient air/wind resistance, R A , vehicle mass-slopped terrain gradient resistance, R G , and additional accelerating force demand from the propulsion engine to overcome the rotating element masses of the engine transmission gear and wheel inertia forces. Each of the mentioned tractive resistances and the rotating elements' inertia shall be fully studied and will be the subject of the next papers in this series.
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Shape Memory Effect of TiNi Short Fiber on Mechanical Properties of TiNi/Al6061 Composite

US Army TACOM-B. Raju
Noveltech-C. L. Xie, M. Hailat, Z. Abedin
Published 2005-04-11 by SAE International in United States
A composite of an aluminum matrix reinforced by short TiNi shape memory alloy (SMA) fibers was fabricated. The processing and thermomechanical behaviors of the composite TiNi/Al6061 were investigated experimentally and analytically. Optimal hot-pressing conditions of TiNi/Al6061 processing were identified. The shape memory effect (SME) was activated by prestraining the composite at the temperature between Ms and As, followed by heating up to Af. SME on mechanical properties, such as microhardness, yield stresses of the composite, were investigated. A computational model for the strengthening mechanism of the short fiber metal matrix composite was utilized to analyze SME on yield stress of the composite. Yield stress of the composite as a function of prestrain was predicted numerically and verified experimentally.
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A Strength-enhanced, High Efficiency Carbon Foam Radiator

US Army TACOM-Jeffrey Kozierowski, Wsewolod Hnatczuk
Florida Atlantic University-X. A. Zhu, C. T. Tsai
Published 2005-04-11 by SAE International in United States
There is a need for high efficiency radiators in liquid cooled military vehicles. It is obvious that the new system should be better than the current Al radiators in terms of thermal performance, military robustness, size, weight and easiness of mass production.For the last ten to fifteen years, a search for new materials has been ongoing. One of the best current candidates is a pitch-based carbon foam that exhibits a superior thermal performance, but with inferior mechanical performance.While developing carbon foam systems, with the intent of overcoming its seriously low mechanical strength, it was also discovered that another serious concern emerged, namely the difficulty in joining, bonding and sealing the carbon foam to the same, or dissimilar material, such as metal or ceramic.This paper presents results of our first stage effort in strengthening carbon foam under an SBIR program funded by the National Automotive Center (NAC) at TACOM, Warren, MI.
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Logistics and Capability Implications of a Bradley Fighting Vehicle with a Fuel Cell Auxiliary Power Unit

US Army TACOM-Heather McKee
Delphi Corporation-Joseph Conover, Harry Husted, John MacBain
Published 2004-03-08 by SAE International in United States
Modern military ground vehicles are dependent not only on armor and munitions, but also on their electronic equipment. Advances in battlefield sensing, targeting, and communications devices have resulted in military vehicles with a wide array of electrical and electronic loads requiring power. These vehicles are typically designed to supply this power via a main internal combustion engine outfitted with a generator. Batteries are also incorporated to allow power to be supplied for a limited time when the engine is off. It is desirable to use a subset of the battlefield electronics in the vehicle while the engine is off, in a mode called “silent watch.” Operating time in this mode is limited, however, by battery capacity unless an auxiliary power unit (APU) is used or the main engines are restarted. Integration of a solid oxide fuel cell (SOFC) auxiliary power unit into a military vehicle has the potential to greatly extend silent watch operating time and capabilities while significantly reducing fuel use.In this paper the results of a study are presented which show the fuel…
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Human Modeling: Controlling Misuse and Misinterpretation

US Army TACOM-Kyle Nebel
Lear Corporation-Scott A. Ziolek
Published 2003-06-16 by SAE International in United States
Human models are viable methods of introducing human factors and ergonomic objectives into the design process at an early stage. Used correctly, they allow users to simulate and analyze potential human-machine interactions saving time and money. As with any model, mistakes can be made. The primary sources of error stem from incorrect use and misinterpretation of the results by the analyst. The development of three-dimensional human modeling software has only compounded these issues by adding a digital subject, itself a human model. This complicates the interpretation and use of these tools by layering one human model on top of another. The purpose of this paper is to highlight common categories of misuse and misinterpretation of digital human models as well as to propose a method for improving user understanding of human models through formal documentation of critical components.
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