Search Results

Over the last two decades, engine research has been mainly focused on reducing fuel consumption in view of compliance with stringent homologation targets and customer expectations. As it is well known, the objective of overall engine efficiency optimization can be achieved only through the improvement of each element of the efficiency chain, of which mechanical constitutes one of the two key pillars (together with thermodynamics). In this framework, the friction reduction for each mechanical subsystems has been one of the most important topics of modern Diesel engine development. In particular, the present paper analyzes the lubrication circuit potential as contributor to the mechanical efficiency improvement, by investigating the synergistic impact of oil circuit design, oil viscosity characteristics (including new ultra-low formulations) and thermal management. For this purpose, a combination of theoretical and experimental tools were used.

In a typical ground vehicle, airflow enters engine compartment through grille and carries heat from the engine, cabin and other auxiliaries through heat exchangers such as radiator, condenser, oil cooler and charge air cooler respectively. The amount of airflow entering the engine compartment is governed by their individual resistances, the grille and engine compartment resistances. Also, this flow adds to drag and deteriorates overall aerodynamic efficiency. It is known as cooling drag which contributes to 8 to 12 percent of overall drag. Aerodynamics and Front End Air Flow (FEAF) development happens through CFD and it demands accurate heat exchanger pressure drop data which is usually obtained from supplier at very early stages of a vehicle development. Historically, this data is found to have significant variations compared to in-house test data.

Substituting alternative materials for conventional materials in automotive applications is an important strategy for reducing environmental burdens over the entire life cycle through weight reduction. Strong, light carbon composites and lightweight metals can potentially be used for components such as body structure, chassis parts, brakes, tie rods, or instrument panel structural beams. There are also proposed uses in conventional and alternative powered vehicles for other advanced materials, including synthetic graphite, titanium, and metals coated with graphite composite, that have special strength, hardness, corrosion resistance, or conductivity properties. The approach used in this paper was to compare the environmental life cycle inventory of parts made from carbon fiber-thermoplastic composites, synthetic graphite, titanium, and graphite coated aluminum, with parts made from conventional steel or aluminum.

Non-circular ducts with strong curvature is commonly used in automobile HVAC system. The geometric cross section of the duct along with the bend angle plays a significant role in pressure drop. The present work aims at computationally analyzing the effect of eight different geometric cross-section ducts with different bend angles ranging from 0 degree to 135 degree on flow and pressure drop characteristics. A comparative study with different duct geometry and the bend angle is performed using fluent code. The effect of duct geometric cross section on secondary velocity and the total pressure loss coefficient for various duct geometries are discussed in detail. It is observed that the curvature of outer wall, slope of top wall and bottom wall plays a significant role in total pressure drop. It is found that the Rectangle-B and Triangle ducts are more sensitive to bend angle whereas Rectangle-A and Semicircle-A are least sensitive to bend angle in terms of total pressure drop.

Sixteen participants aged 55–65yrs provided deBoer scale ratings of discomfort glare for a vehicle with horizontally swiveling HID headlamps and a vehicle with the same headlamps that did not swivel in eight scenarios staged in a darkened parking lot. Participants, who were seated in the driver’s position of a stationary vehicle and instructed when to look, viewed the oncoming test vehicles in scenarios of 180m left turn, 180m right turn, 80m left turn, 80m right turn, left turn beside participant vehicle, crossing left in front of participant vehicle, right turn beside participant vehicle, and straightaway, in counterbalanced presentation orders. The swiveling headlamp vehicle provided statistically lower glare ratings in both 180m curves and the 80m right curve and statistically lower or similar in the intersection scenarios than the fixed headlamp vehicle.

Software development tools can be used in conjunction with test automation tools to validate controller software. Test automation tools must have an open architecture to interface with all the different software and hardware components, within a control validation project. Therefore software development tools like Matlab/Simulink will be able to exchange data via real time interface software with test automation tools. The test automation tool must be flexible to pass data back and forth from/to Microsoft standard software programs like Excel.

To replicate on-road brake test cycle of cooling or heating through Computational Fluid Dynamics (CFD) simulations, the vehicle model with brake assembly must be solved in transient mode. However, such simulations require significant computational time owning to the physics involved in computing the variation of temperature with time. A methodology developed using commercial CFD tools to predict the Heat Transfer Coefficient (h), Cooling Coefficient (b) and rotor temperatures is described in this paper. All the three modes of heat transfer: conduction, convection and radiation are considered in the current method. Heat transfer coefficients from the CFD simulations are exported to Computer Aided Engineering (CAE) tools to validate the Brake Rotor Thermal Coning caused by high thermal gradients in brake rotor.

The objective of the paper is to outline a CFD based lumped parameter method that compares the thermal performance of brake rotors, predicts the transient temperatures and brake lining wear in vehicle. A two-pronged approach was developed for this purpose. A rotor stand-alone model was used to predict rotor performance curves. Simultaneously heat transfer coefficients of the brake rotor were computed corresponding to the rotor performance curves and the appropriate heat transfer correlations were established. The second part of this approach involved developing a brake model in a vehicle and solving for the air flow through rotors in different vehicles at various speeds. These rotor flows were cross-referenced with the rotor performance curves, generated earlier for that rotor, to compute the heat transfer coefficients in the vehicle.

Aerodynamic performance of on-road vehicle can be improved by using portable enablers on rear portion of the vehicle which can be attached or detached by the owner himself. Objective of this study is to explore the possibility of using such portable enablers to substantially reduce the drag of the vehicle. Enablers with specific convex shapes are created on various positions of rear portion of vehicle and simulated with CFD solver FLUENT. Compact sedan vehicle was considered in this study. Preprocessing is performed and specific fluid domains are captured. Generally, aerodynamic enablers are integrated parts of the vehicle. This paper emphasizes on consideration of portable enablers which can be used while cruising for longer distances. Drag improvement of ΔCD = 0.006~0.009 was achieved by introducing the specific enabler based on its position, shape and dimension. This paper also suggests methods of attachment of portable enabler to the vehicle.