Refine Your Search

Topic

Author

Affiliation

Search Results

Technical Paper

A study on the effect of different glasses and its properties on vehicle cabin during soaking at hot ambient conditions using 1D simulation

2020-04-14
2020-01-0956
Increase in traffic conditions and global increase in the ambient temperature during the summer season, heat load in the vehicle cabin is also increasing, creating a huge thermal discomfort for the passengers. There are two scenarios in which these adverse conditions can be a problem, one is when driving the vehicle in traffic condition and another one is when the vehicle is parked in the open sun both during the summer season. While for the first scenario, at least the air conditioner can be switched on, for the soaking scenario the cabin temperature can reach alarming levels which may have serious discomfort and health effects on the human entering vehicle. Although there are options of remote switching on of air conditioners, they are restricted to vehicles having an automatic transmission only.
Technical Paper

IC engine internal cooling system modelling using 1D-CFD methodology

2020-04-14
2020-01-1168
Internal combustion engine gets heated up due to continuous combustion of fuel. To keep engine working efficiently and prevent components damage due to very high temperature, the engine needs to be cooled down. Based on power output requirement and provision for cooling system, every engine has it’s unique cooling system. Liquid based cooling systems are majorly implemented in automobile. It’s important to keep in mind that during design phase that, cooling the engine will lower the power to fuel consumption ratio. Therefore, during lower ambient conditions, the cooling system should be able to uniformly increase the temperature of the engine components, engine oil and transmission oil. This is achieved by circulating the coolant through cooling jacket, engine oil heater and transmission oil heater, which will be heated by the combustion heat.
Technical Paper

Assessing Thermomechanical Fatigue of a Cast Aluminum Alloy Cylinder Head of an Internal Combustion Engine

2020-04-14
2020-01-1077
Cast aluminum alloys are used for cylinder heads in internal combustion engines to meet low weight, high strength (lightweight) design requirements. In the combustion chamber, the alloy experiences harsh operating conditions; i.e., temperature variation, limitation of thermal expansion, chemical reaction, corrosion, oxidation, and chemical deposition. Under these conditions, thermomechanical fatigue (TMF) damage arises in the form of mechanical damage, environmental (oxidation) damage, and creep damage. In the present work, several important properties that influence the TMF life of the cylinder head have been identified through TMF and finite element analysis (FEA). The results show that improving the strength at high temperatures helps improve TMF life on the exhaust side of the head. On the other hand, improving strength and ductility lengthen TMF life at low temperature on the intake side.
Technical Paper

VIRTUAL METHOD FOR ELECTRONIC STOP-START SIMULATION & VDV PREDICTION USING MODIFIED DISCRETE SIGNAL PROCESSING FOR SHORT TIME SIGNALS

2020-04-14
2020-01-1270
Electronic Stop-Start (ESS) system automatically stops and restarts the engine to save energy, improve fuel consumption and reduce emissions when the vehicle is stationary during traffic lights, traffic jams etc. The start and stop events cause unwanted vibrations at the seat track which induce discomfort to the drivers and passengers in the vehicle. These events are very short duration events, usually taking less than a second. Time domain analysis can help in simulating this event but it is difficult to see modal interactions and root cause issues. Modal transient analysis also poses a limitation on defining frequency dependent stiffness and damping for multiple mounts. This leads to inaccuracy in capturing mount behavior at different frequencies. Most efficient way to simulate this event would be by frequency response analysis using modal superposition method.
Technical Paper

CAE Modeling Static and Fatigue Performance of Short Glass Fiber Reinforced Polypropylene Coupons and Components

2020-04-14
2020-01-1309
Fiber reinforced polypropylene (FRPP) is a typical anisotropic composite and its material properties highly depend on the fiber orientations within the material. To improve accuracy in prediction of durability performance of structures made of this kind of composite material, simulation of manufacturing process is necessary to obtain distribution of fibers and their orientations at every location of the structure. This paper describes a CAE modeling techniques to simulate 1) injection molding process, 2) static and fatigue performance of coupons and 3) static and fatigue performance of components made of 30% FRPP. Details of CAE model setup, analysis procedures and correlation between analysis and test results are presented. In this study, various fiber orientation (0, 20, 90 degrees & knit line), temperature (-40, 23 and 80 degree C) and mean stress (R=-1.0, -0.5, -0.2, 0.1 and 0.4) have been considered.
Technical Paper

Numerical Modeling of Direct-Oil-Cooled Electric Motor for Effective Thermal Management

2020-04-14
2020-01-1387
Electric motor performance is critically limited by amount of heat that can be effectively dissipated. Recent developments in electric motor cooling have been employing direct oil spray/splash based cooling for improved performance. Simulation of distinct two phase (air and oil) flow and associated heat transfer for such applications has been computationally very challenging, hence limited in modeling details. This paper describes a two phase numerical study in which oil flow and heat transfer within a direct-oil-cooled electric motor are analyzed using CFD software. This analysis determines the oil flow field around the electric motor and identifies potential hot spots. The temperature of motor components is predicted using a conjugate heat transfer approach. This method is used to generate a detailed temperature field of all the components of motor at different operating conditions. Numerical results are compared with the temperature measurements at discrete locations in motor.
Technical Paper

An Iterative Histogram-Based Optimization of Calibration Tables in a Powertrain Controller

2020-04-14
2020-01-0266
To comply with the stringent fuel consumption requirements, many automobile manufacturers have launched vehicle electrification programs which are representing a paradigm shift in vehicle design. Looking specifically at powertrain calibration, optimization approaches were developed to help the decision-making process in the powertrain control. Due to computational power limitations the most common approach is still the use of powertrain calibration tables in a rule-based controller. This is true despite the fact that the most common manual tuning can be quite long and exhausting, and with the optimal consumption behavior rarely being achieved. The present work proposes a simulation tool that has the objective to automate the process of tuning a calibration table in a powertrain model. To achieve that, it is first necessary to define the optimal reference performance.
Technical Paper

A Dynamic Programming Algorithm for HEV Powertrains Using Battery Power as State Variable

2020-04-14
2020-01-0271
One of the first steps in powertrain design is to assess its best performance and consumption in a virtual phase. Regarding hybrid electric vehicles (HEVs), it is important to define the best mode profile through a cycle in order to maximize fuel economy. To assist in that task, several off-line optimization algorithms were developed, with Dynamic Programming (DP) being the most common one. The DP algorithm generates the control actions that will result in the most optimal fuel economy of the powertrain for a known driving cycle. Although this method results in the global optimum behavior, the DP tool comes with a high computational cost. The charge-sustaining requirement and the necessity of capturing extremely small variations in the battery state of charge (SOC) makes this state vector an enormous variable. As things move fast in the industry, a rapid tool with the same performance is required.
Technical Paper

Development of a Novel Test System to Determine the Durability of RTV Gasket Material

2020-04-14
2020-01-1069
This paper describes a laboratory-based test system and procedure for determining the durability of RTV sealant with fretting movement. A test machine is described in which shear and tensile stress-generating displacements at room temperature and temperature of 100°C are produced to load an RTV seal. The test system utilizes an air pressurized hollow cylinder with a cap sealed by RTV sealant on a reciprocating test rig. An external air leakage monitoring system detects the health of the tested RTV seal. When air leakage occurs, the seal is determined to have failed. RTV sealant used in the test was fully cured at room temperature and then aged with engine oil. In the experiments, a total of 6 displacements were used to generate cycle/amplitude graphs for both shear and tensile modes. Failures were determined to be caused by the loss of adhesion in tensile mode, and by crack nucleation due to the special step design in shear mode.
Technical Paper

Assessing the Impact of Lubricant and Fuel Composition on LSPI and Emissions in a Turbocharged Gasoline Direct Injection Engine

2020-04-14
2020-01-0610
Downsized turbocharged gasoline direct injection (TGDI) engines with high specific power and torque can enable reduced fuel consumption in passenger vehicles while maintaining or even improving on the performance of larger naturally aspirated engines. However, high specific torque levels, especially at low speeds, can lead to abnormal combustion phenomena such as knock or Low-Speed Pre-Ignition (LSPI). LSPI, in particular, can limit further downsizing due to resulting and potentially damaging mega-knock events. Herein, we characterize the impacts of lubricant and fuel composition on LSPI frequency in a TGDI engine while specifically exploring the correlation between fuel composition, particulate emissions, and LSPI events. Our research shows that: (1) oil composition has a strong impact on LSPI frequency and that LSPI frequency can be reduced through a carefully focused approach to lubricant formulation.
Technical Paper

Thermal Modeling of DC/AC Inverter for Electrified Powertrain Systems

2020-04-14
2020-01-1384
A DC-to-AC main Power Inverter Module (PIM) is one of the key components in electrified powertrain systems. Accurate thermal modeling and temperature prediction of a PIM is critical to the design, analysis, and control of a cooling system within an electrified vehicle. PIM heat generation is a function of the electric loading applied to the chips and the limited heat dissipation within what is typically compact packaging of the Insulated Gate Bipolar Transistor (IGBT) module inside the PIM. This work presents a thermal modeling approach for a 3-phase DC/AC PIM that is part of an automotive electrified powertrain system. Heat generation of the IGBT/diode pairs under electric load is modeled by a set of formulae capturing both the static and dynamic losses of the chips in the IGBT module. A thermal model of the IGBT module with a simplified liquid cooling system generates temperature estimates for the PIM.
Technical Paper

Utilization of Bench Testing in Vehicle Thermal System Development for Extreme Cold Ambient Condition

2020-04-14
2020-01-1390
Automotive thermal systems are becoming complicated each year. The powertrain efficiency improvement initiatives are driving transmission and engine oil heaters into coolant network design alternatives. The initiatives of electrified and autonomous vehicles are making coolant networks even more complex. The coolant networks these days have many heat exchangers, electric water pumps and valves, apart from typical radiators, thermostat and heater core. Some of these heat exchangers, including cabin heaters deal with very small amount of coolant flow rates at different ambient conditions. This paper describes how viscosity can be a major reason for simulation inaccuracy, and how to deal with it for each component in the coolant network. Both experimental and computational aspects have been considered in this paper with wide range of ambient temperatures.
Technical Paper

Development of a Computational Algorithm for Estimation of Lead Acid Battery Life

2020-04-14
2020-01-1391
The performance and durability of the lead acid battery is highly dependent on the internal battery temperature. The changes in internal battery temperatures are caused by several factors including internal heat generation and external heat transfer from the vehicle under-hood environment. Internal heat generation depends on the battery charging strategy and electric loading. External heat transfer effects are caused by customer duty cycle, vehicle under-hood components and under-hood ambient air. During soak conditions, the ambient temperature can have significant effect on battery temperature after a long drive for example. Therefore, the temperature rise in a lead-acid battery must be controlled to improve its performance and durability. In this paper a thermal model for lead-acid battery is developed which integrates both internal and external factors along with customer duty cycle to predict battery temperature at various driving conditions.
Technical Paper

Battery Entropic Heating Coefficient Testing and Use in Cell-Level Loss Modeling for Extreme Fast Charging

2020-04-14
2020-01-0862
To achieve an accurate estimate of losses in a battery it is necessary to consider the reversible entropic losses, which may constitute over 20% of the peak total loss. In this work, a procedure for experimentally determining the entropic heating coefficient of a lithium-ion battery cell is developed. The entropic heating coefficient is the rate of change of the cell’s open-circuit voltage (OCV) with respect to temperature; it is a function of state-of-charge (SOC) and temperature and is often expressed in mV/K. The reversible losses inside the cell are a function of the current, the temperature, and the entropic heating coefficient, which itself is dependent on the cell chemistry. The total cell losses are the sum of the reversible and irreversible losses, where the irreversible losses consist of ohmic losses in the electrodes, ion transport losses, and other irreversible chemical reactions.
Technical Paper

Equivalence Factor Calculation for Hybrid Vehicles

2020-04-14
2020-01-1196
Within a hybrid electric vehicle, given a power request initiated by pedal actuation, a portion of overall power may be generated by fuel within an internal combustion engine, and a portion of power may be taken from or stored within a battery via an e-machine. Generally speaking, power taken from a vehicle battery must eventually be recharged at a later time. Recharge energy typically comes ultimately from engine generated power (and hence from fuel), or from recovered braking energy. A hybrid electric vehicle control system attempts to identify when to use each type of power, i.e., battery or engine power, in order to minimize overall fuel consumption. In order to most efficiently utilize battery and fuel generated power, many HEV control strategies utilize a concept wherein battery power is converted to a scaled fueling rate.
Technical Paper

Guidelines for SUV Bodywork Design Focused on Aerodynamic Drag Reduction Using the Generic AeroSUV Model

2020-04-14
2020-01-0478
SUV Aerodynamics has received increased attention as the stake this segments holds in the automotive market keeps growing year after year, as well as its direct impact on fuel economy. Understanding the key physics in order to accomplish both fuel efficient and aesthetic products is paramount, which indeed gave origin to a major initiative to foster collaborative aerodynamic research across academia and industry, the so-called DrivAer model. In addition to this sedan-based model, a new dedicated SUV generic model, called AeroSUV [1], has been introduced in 2019, also intended to provide a common framework for aerodynamic research for both experimental work and numerical simulation validation. The present paper provides an area of common ground for SUV bodywork design focused on aerodynamic drag reduction by investigating both Estate and Fast back configurations of the generic AeroSUV model.
Technical Paper

Sensitivity Analysis of Aerodynamic Drag Coefficient to EPA Coastdown Ambient Condition Variation

2020-04-14
2020-01-0666
The test cycle average drag coefficient is examined for the variation of allowable EPA coastdown ambient conditions. Coastdown tests are ideally performed with zero wind and at SAE standard conditions. However, often there is some variability in actual ambient weather conditions during testing, and the range of acceptable conditions is further examined in detail as it pertains to the effect on aerodynamic drag derived from the coastdown data. In order to “box” the conditions acceptable during a coastdown test, a sensitivity analysis was performed for wind averaged drag (CD¯) as well as test cycle averaged drag coefficients (CDWC) for the fuel economy test cycles. Test cycle average drag for average wind speeds up to 16 km/h and temperatures ranging from 5C to 35C, along with variation of barometric pressure and relative humidity are calculated. The significant effect of ambient cross winds on coastdown determined drag coefficient is demonstrated.
Technical Paper

Accelerated Sizing of a Power Split Electrified Powertrain

2020-04-14
2020-01-0843
Component sizing generally represents a demanding and time-consuming task in the development process of electrified powertrains. A couple of processes are available in literature for sizing the hybrid electric vehicle (HEV) components. These processes employ either time-consuming global optimization techniques like dynamic programming (DP) or near-optimal techniques that require iterative and uncertain tuning of evaluation parameters like the Pontryagin’s minimum principle (PMP). Recently, a novel near-optimal technique has been devised for rapidly predicting the optimal fuel economy benchmark of design options for electrified powertrains. This method, named slope-weighted energy-based rapid control analysis (SERCA), has been demonstrated producing results comparable to DP, while limiting the associated computational time by near two orders of magnitude.
Technical Paper

EGR Distribution in an Intake Manifold: Analysis, Dynamometer Correlation and Prediction

2020-04-14
2020-01-0840
Every passing year automotive engineers are challenged to attain higher fuel economy and improved emission targets. One widely used approach is to use Cooled Exhaust Gas Recirculation (CEGR) to meet these objectives. Apart from reducing emissions and improving fuel economy, CEGR also plays a significant role in knock mitigation in spark ignited gasoline engines. Generally, CEGR is introduced into the intake manifold in SI gasoline engine. Even though the benefits of using CEGR are significant, they can be easily negated by the uneven CEGR flow distribution between the cylinders, which can result in combustion instability. This paper describes the application of co-simulation between one and three dimensional tools to accurately predict the distribution of CEGR to the cylinders and the effect of its distribution on engine performance.
Technical Paper

Impact of Active-Grille Shutter Position on Vehicle Air-Conditioning System Performance and Energy Consumption in Real World Conditions

2020-04-14
2020-01-0947
Active grille shutter (AGS) in a vehicle provides aerodynamic benefit at high vehicle speed by closing the front-end grille opening. At the same time this causes lesser air flow through the cooling module which includes the condenser. This results in higher refrigerant pressure at the compressor outlet. Higher head pressure causes the compressor to work more, thereby possibly negating the aerodynamic benefits towards vehicle power consumption. This paper uses a numerical method to quantify the compressor power consumed in different scenarios and assesses the impact of AGS closure on total vehicle energy consumption. The goal is to analyze the trade-off between the aerodynamic performance and the compressor power consumption at high vehicle speeds and mid-ambient conditions. These so called real world conditions represent highway driving at mid-ambient temperatures where the air-conditioning (AC) load is not heavy.
X