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Technical Paper

An Experimental Study of the Impact of Underbody Roughness on the Instantaneous Wake Flow Topology behind a Truck Geometry

2018-04-03
2018-01-0714
The turbulent wake behind a truck is responsible for a considerable proportion of the total aerodynamic drag. There is evidence to suggest that the underbody flow affects the wake topology, although this interaction is not well understood. Typical truck trailer underbodies are geometrically very complex and have a range of bluff bodies - such as the wheel and axle assembly, structural beams or the secondary fuel tank for refrigerated trucks - attached. These components block the underbody flow and erode its momentum. However, most of the previous studies of the wake flow have used models with clean underbodies. It is thus uncertain whether the wake shapes found by these studies accurately represent the wake topology behind a real truck with a detailed underbody.
Technical Paper

Investigation and Development of Underbody Aerodynamic Drag Reduction Devices for Trailer Trucks

2018-04-03
2018-01-0707
It is well known that the underbody region of a tractor-trailer is responsible for up to 30% of the aerodynamic drag. This is the highest drag created by any region of a tractor-trailer. There are a number of underbody drag-reduction devices available on the market but they create a few operational issues, such as low ground clearance and ice collection, which inhibit their mass market appeal. In this paper, a novel concept of an underbody aerodynamic device is developed and investigated. The underbody device is a combination of a ramp and a side skirt; which are optimized simultaneously. In addition, the device is made collapsible to facilitate easy storage when not in use (i.e., city driving). NASA’s Generic Conventional Model (GCM); a 1/8th scale model of a generic class-8 tractor-trailer is used to evaluate and optimize the concept. The GCM allows the concept to be applicable to a wider range of tractor-trailers.
Technical Paper

Simplifications Applied to Simulation of Turbulence Induced by a Side View Mirror of a Full-Scale Truck Using DES

2018-04-03
2018-01-0708
In this paper, the turbulent flow induced by a production side-view mirror assembled on a full-scale production truck is simulated using a compressible k-ω SST detached eddy simulation (DES) approach -- the improved delayed DES (IDDES). The truck configuration consists of a compartment and a trailer. Due to the large size and geometric complexity of the configuration, some simplifications are applied to the simulation. A purpose of this work is to investigate whether the simplifications are suitable to obtain the reasonable properties of the flow near the side-view mirror. Another objective is to study the aerodynamic performances of the mirror. The configuration is simplified regarding two treatments. The first treatment is to retain the key exterior components of the truck body while removing the small gaps and structures. Furthermore, the trailer is shaped in an apex-truncated square pyramid.
Technical Paper

Investigation of Particle Number Emission Characteristics in a Heavy-Duty Compression Ignition Engine Fueled with Hydrotreated Vegetable Oil (HVO)

2018-04-03
2018-01-0909
Diesel engines are one of the most important power generating units these days. Increasing greenhouse gas emissions level and the need for energy security has prompted increasing research into alternative fuels for diesel engines. Biodiesel is the most popular amongst the alternatives for diesel fuel as it is biodegradable, renewable and can be produced domestically from vegetable oils. In recent years, hydro-treated vegetable oil (HVO) has also gained popularity due to some of its advantages over biodiesel such as higher cetane number, lower deposit formation, storage stability etc. HVO is a renewable, paraffinic biobased alternative fuel for diesel engines similar to biodiesel. Unlike biodiesel, the production process for HVO involves hydrogen as catalyst instead of methanol which removes oxygen content from vegetable oil.
Technical Paper

A Consolidated Investigation on LPG as an Alternative Fuel for Public Utility Jeepneys

2018-04-03
2018-01-0917
This paper presents the results of a two-phase Philippine study to determine the actual mileage (km/liter) of in-use diesel and LPG (liquefied petroleum gas or Auto-LPG) public utility jeepneys plying two separate Metro Manila urban routes using both on-road and chassis dynamometer tests. Measured average load factor in on-road tests was 60-70%. Dynamometer tests at 100% load factor utilized drive cycles derived from on-road speed data. A “diesel equivalent mileage” of actual LPG mileage, deemed indicative of LPG “fuel energy conversion efficiency” relative to diesel, was calculated (based solely on fuel heating values and densities) for comparing actual mileage from both fuels. The LPG actual mileage in both on-road and laboratory tests was lower than diesel mileage. In on-road tests, the LPG actual mileage was lower than diesel actual mileage by about the same percentage LPG heating value was lower than diesel’s per liter of fuel.
Technical Paper

Fuzzy PID Based Optimization of Starting Control for AMT Clutch of Heavy-duty Trucks

2018-04-03
2018-01-1166
Starting control has become a troublesome issue in the developing field of the control system for heavy-duty trucks, due to the complexity of vehicle driving and the variability of driver's intention. The too fast clutch engagement may result in serious impact, influence on the comfort and fatigue life, and even the engine flameout, while the too slow clutch engagement may lead to long time of friction, the increased temperature, and accelerated wear of friction pair, as well as influence on the power performance and fatigue life[1]. Therefore, the key technique of starting control is clutch engagement control, for which the fuzzy PID based optimization of starting control for AMT clutch is proposed, with the pneumatic AMT clutch of heavy-duty trucks as the research object.
Technical Paper

Development of a Pre-Chamber Ignition System for Light Duty Truck Engine

2018-04-03
2018-01-1147
In this article the development of a combustion system with a fuel-scavenged pre-chamber is described. Such a system is commonly used in large-bore engines operated with extremely lean mixtures. The authors implemented the scavenged pre-chamber into a light duty truck-size engine with a bore of 102 mm. The lean burn strategy is intended to achieve very low nitrogen oxide (NOx) emissions at low load. At full load a stoichiometric mixture strategy is applied to achieve sufficient power density while simultaneously enabling the use of a relatively simple three-way catalytic converter for exhaust gas aftertreatment. This work outlines the pre-chamber design features and introduces the results of an experimental investigation of the effect of pre-chamber ignition on a single cylinder testing engine.
Technical Paper

Infrared Borescopic Evaluation of High-Energy and Long-Duration Ignition Systems for Lean/Dilute Combustion in Heavy-Duty Natural-Gas Engines

2018-04-03
2018-01-1149
Natural gas (NG) is attractive for heavy-duty (HD) engines for reasons of cost stability, emissions, and fuel security. NG cannot be reliably compression-ignited, but conventional gasoline ignition systems are not optimized for NG and are challenged to ignite mixtures that are lean or diluted with exhaust-gas recirculation (EGR). NG ignition is particularly challenging in large-bore engines, where completing combustion in the available time is more difficult. Using two high-speed infrared (IR) cameras with borescopic access to one cylinder of an HD NG engine, the effect of ignition system on the early flame-kernel development and cycle-to-cycle variability (CCV) was investigated. Imaging in the IR yielded strong signals from water emission lines, which located the flame front and burned-gas regions and obviated image intensifiers. A 9.7-liter, six-cylinder engine was modified to enable exhaust-gas recirculation and to provide optical access.
Technical Paper

Development of 80- and 100- Mile Work Day Cycles Representative of Commercial Pickup and Delivery Operation

2018-04-03
2018-01-1192
When developing and designing new technology for integrated vehicle systems deployment, standard cycles have long existed for chassis dynamometer testing and tuning of the powertrain. However, to this day with recent developments and advancements in plug-in hybrid and battery electric vehicle technology, no true “work day” cycles exist with which to tune and measure energy storage control and thermal management systems. To address these issues and in support of development of a range-extended pickup and delivery Class 6 commercial vehicle, researchers at the National Renewable Energy Laboratory in collaboration with Cummins analyzed 78,000 days of operational data captured from more than 260 vehicles operating across the United States to characterize the typical daily performance requirements associated with Class 6 commercial pickup and delivery operation.
Technical Paper

Influences on Energy Savings of Heavy Trucks Using Cooperative Adaptive Cruise Control

2018-04-03
2018-01-1181
An integrated adaptive cruise control (ACC) and cooperative ACC (CACC) was implemented and tested on three heavy-duty tractor-trailer trucks on a closed test track. The first truck was always in ACC mode, and the followers were in CACC mode using wireless vehicle-vehicle communication to augment their radar sensor data to enable safe and accurate vehicle following at short gaps. The fuel consumption for each truck in the CACC string was measured using the SAE J1321 procedure while travelling at 65 mph and loaded to a gross weight of 65,000 lb, demonstrating the effects of: inter-vehicle gaps (ranging from 3.0 s or 87 m to 0.14 s or 4 m, covering a much wider range than previously reported tests), cut-in and cut-out maneuvers by other vehicles, speed variations, the use of mismatched vehicles (standard trailers mixed with aerodynamic trailers with boat tails and side skirts), and the presence of a passenger vehicle ahead of the platoon.
Technical Paper

Design and Development of Active On-Board Alcohol Detection System with Safety Features for Commercial Vehicles

2018-04-03
2018-01-0602
Drink & drive has caused the increased rate of commercial vehicle accidents in the world due to the slow response to judgment and reasoning. According to research study 70% accidents are happened due to drunk & drive, it causes loss of human life and economic damage. Research has proven that drunk drivers exhibit aggressive driving behavior and apply more force during braking. While public health awareness and legal restrictions can assist in educating and discouraging people from drunk & drive, a more fool-proof method is not available in the market for commercial vehicles. Currently, a low cost, fail-safe onboard alcohol detection, and vehicle safety system is the need of the hour. This paper deals with the design & development of a low cost active onboard breath alcohol detection system and it’s on vehicle validation. Further, it explains the type of alcohol detection sensor used, controller design, logic programming and system packaging.
Technical Paper

Optimization Design of Rear-Engine Bus Cooling System Based on 1D/3D Coupling Simulation

2018-04-03
2018-01-0771
This study investigated the effects of underhood structure parameters (two types of air ducts, two types of inlet grilles and the opening angle of inlet grilles) on the cooling characteristics of the rear-engine bus; then, the optimum design scheme of the underhood was determined. The air-side resistance load of the cooling system, which is based on fan performance, was selected as the optimization objective. Simulations were created based on a porous media model and standard a k-ε model. The next step was to build a 1D/3D coupling simulation to utilize the advantages of 1D simulation’s fast convergence speed and 3D simulation’s extensive research range. Besides, the use of 1D/3D coupling simulation can efficiently avoid the errors of simulation results which arise from the non-uniform airflow on the cooling module. Results show that the airflow rate of the rectangular air duct increased by 7 to 11percent.
Technical Paper

The Durability Test Setup of Test Rig for the Rear Axle of a LCV and Its Validation in Adams/View

2018-04-03
2018-01-1229
This paper deals with the durability life for the new development of the rear axle of a light commercial vehicle (LCV) which has been in the market. The test fixture has been constructed for the MTS bench tests. Simultaneously the ADAMS/View model of the rear axle has been created. The force-displacement graphs obtained from the bench tests and from the ADAMS/View simulation have been compared to each other. The fatigue tests have been performed at 2.5 g bump condition and it has been possible to simulate the low and high loads. The aim of this study has been to validate the test fixture and the test conditions.
Technical Paper

Working Load Measurement and Analysis of Bolted Joint under Off-road Vehicle Operation

2018-04-03
2018-01-1234
In this study, we propose a method of measuring and analyzing the load on bolted joints used in a machine under off-road vehicle operation. Working load measurement under actual machine operation and the results of its analysis are shown as load frequency diagrams. An example of the measurement analysis of a load (three types of load: axial force, bending moment, and torsional torque) added to a bolted joint shank during actual machine operation is shown. In this paper, we describe how to apply the results of load analysis to the load condition at the design and experimental development stages.
Technical Paper

Effects of Diesel Injection Parameters in a Heavy Duty Iso-Butanol/Diesel Reactivity Controlled Compression Ignition (RCCI) Engine

2018-04-03
2018-01-0197
Due to the higher combustion efficiency and fewer exhaust emissions in comparison with other diesel combustion strategies, RCCI combustion attracted lots of attention. Using two fuels with different reactivities lead to lower fuel consumption and considerably less NOx and PM emissions. An investigation has been carried out in order to examine the simultaneous effects of diesel injection pressure and single injection timing on the emissions formation and engine performance in a heavy duty single-cylinder butanol-diesel reactivity controlled compression ignition (RCCI) diesel engine. A reduced chemical n-heptane-n-butanol-PAH mechanism which consists of 76 species and 349 reactions has been used to simulate the combustion process of the dual-fuel diesel engine.
Technical Paper

Observations of Soot Optical Property Characteristics Using High-Speed, Multiple Wavelength, Extinction Imaging in Heavy-Duty Diesel Sprays

2018-04-03
2018-01-0233
Soot formation in high-pressure sprays of n-dodecane is quantified under conditions relevant to heavy-duty diesel engines. Sprays are injected from a single-hole diesel injector belonging to the family of Engine Combustion Network (ECN) Spray D injectors. Soot optical thickness and the total soot mass are quantified using a high-speed extinction imaging diagnostic with incident light wavelengths of 623 nm and 850 nm. The total soot mass is derived from the measured optical thickness using a non-dimensional extinction coefficient (ke) based on the Rayleigh-Debye-Gans approximation for fractal aggregates (RDG-FA). In a previous work, a near unity ke ratio was observed for extinction measurements using incident light at 406 nm and 520 nm-suggesting invariance in the complex refractive index (m = n + κi) of soot at these visible wavelengths; however, the present work demonstrates a significant difference in m for measurements with infrared incident light.
Technical Paper

Advanced Combustion for Improved Thermal Efficiency in an Advanced On-Road Heavy Duty Diesel Engine

2018-04-03
2018-01-0237
For internal combustion engines, the compression ratio (r) is defined as the ratio of volume at bottom dead center to the volume at top dead center and is a fundamental design parameter influencing the thermodynamic operation of the modern combustion engine. Thermodynamic cycle analysis can show that thermal efficiency increases as the compression ratio increases. An increase in the compression ratio changes the cycle such that peak compression pressure and temperatures are increased resulting in subsequent increases in the peak combustion pressure and temperature. Since the average temperature of heat addition is increased in the cycle, the thermal efficiency would theoretically increase as long as both cycles had the same heat rejection processes. These changes in peak pressure and temperature of the cycle must also be evaluated in terms of anticipated increases in engine friction and changes to the combustion duration respectively.
Technical Paper

An Optical Characterization of Dual-Fuel Combustion in a Heavy-Duty Diesel Engine

2018-04-03
2018-01-0252
Dual fuel (DF) combustion technology as a feasible approach controlling engine-out emissions facilitates the concept of fuel flexibility in diesel engines. The abundance of natural gas (90-95% methane) and its relatively low-price and the clean-burning characteristic has attracted the interest of engine manufacturers. Moreover, with the low C/H ratio and very low soot producing tendency of methane combined with high engine efficiency makes it a viable primary fuel for diesel engines. However, the fundamental knowledge on in-cylinder combustion phenomena still remains limited and needs to be studied for further advances in the research on DF technology. The objective of this study is to investigate the ignition delay with the effect of, 1) methane equivalence ratio, 2) intake air temperature and 3) pilot ratio on the diesel-methane DF-combustion. Combustion phenomenon was visualized in a single cylinder heavy-duty diesel engine modified for DF operations with an optical access.
Technical Paper

Videogrammetry in Vehicle Crash Reconstruction with a Moving Video Camera

2018-04-03
2018-01-0532
In an accident reconstruction, vehicle speeds and positions are always of interest. When provided with scene photographs or fixed-location video surveillance footage of the crash itself, close-range photogrammetry methods can be useful in locating physical evidence and determining vehicle speeds and locations. Available 3D modeling software can be used to virtually match photographs or fixed-location video surveillance footage. Dash- or vehicle-mounted camera systems are increasingly being used in light vehicles, commercial vehicles and locomotives. Suppose video footage from a dash camera mounted to one of the vehicles involved in the accident is provided for an accident reconstruction but EDR data is unavailable for either of the vehicles involved. The literature to date describes using still photos to locate fixed objects, using video taken from stationary camera locations to determine the speed of moving objects or using video taken from a moving vehicle to locate fixed objects.
Technical Paper

Introduction to Traffic Signal Data Loggers and their Application to Accident Reconstruction

2018-04-03
2018-01-0527
Each year in the United States, approximately 1 million collisions occur at signalized intersections, representing over 15% of all collisions and almost 9% of traffic fatalities. Engineers seeking to understand the roadway, vehicular, and driver factors related to these collisions are often asked to investigate and assess the traffic signal timing, right of way issues, and the signal indications displayed to involved drivers during the period of time leading up to and including the impact events. Until relatively recently, investigators were limited by the absence of any recording devices within the systems used for traffic signal phasing and timing. Accident reconstruction methods have long relied on the generalized signal phasing and timings programmed for that intersection by the responsible jurisdiction, combined with the vehicle dynamics calculated for the collision sequence in conjunction with witness testimony regarding signal indications and phase changes.
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