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Cooling Fan Selection in Power Car Application: CFD/FEA Coupled Approach

Cummins Inc.-Mukesh Kumar, Vitthal Khandagale, Prashant Kelkar, Rohit Saha
  • Technical Paper
  • 2019-01-0900
To be published on 2019-04-02 by SAE International in United States
This paper describes the methodology used to select application based fan that has optimum operating characteristics in terms of cooling air flow rate, fan power, noise and structural strength. The process uses 1D one-way CFD-FEA coupling approach in highly non-uniform actual flow field inside application. As part of different fan evaluation, full rail coach Underhood simulations were carried out using steady state 3D computational fluid dynamics (CFD) approach. For each fan option fan power, air flow rate and surface acoustic power is evaluated. Pressure profiles on fan blades are studied to assess effect of non-uniform downstream air passage designs. Surface acoustic power is calculated using Broadband noise source model in Fluent. Finite Element Analysis simulation is done in Ansys. Surface pressure profiles over fan blades are imported from 3D CFD are used in finite element analysis (FEA) simulations. Analyses are carried out blade linear and non-linear properties. Equivalent fully reversed stress is calculated based on Goodman program. It can be concluded from simulation study that, CFD-FEA coupled approach can be used to predict and optimize…

An Interactive Vehicle Recommender System Based on Decision Trees and Multi-Armed Bandits

Carnegie Mellon University-Tong Yu, Ole Mengshoel
Ford Motor Company-Dominique Meroux, Zhen Jiang
  • Technical Paper
  • 2019-01-1079
To be published on 2019-04-02 by SAE International in United States
Recommender systems guide a user to useful objects in a large space of possible options in a personalized way. In this paper, we study how to make recommendations for vehicle purchases. This can effectively reduce the human labor in the traditional setting, where customers get recommended vehicles through conversations with the salesmen in dealerships. Comparing a vehicle recommender system to one in other application domains (movies, music, etc.), we identify two major challenges. First, customers usually only purchase a limited number of vehicles, compared to the number of movies or songs. Thus, it is difficult to obtain rich information about a user's purchase history. Second, the content information obtained about the users (demographic, vehicle preference, etc.) is also very limited during their short stay in the dealership. To address these two challenges, we propose an interactive vehicle recommender system based on the methods of decision tree classification and multi-armed bandit. The decision tree effectively selects important questions for the user and understands the user's preference. With these preference as prior information, the multi-armed bandit algorithm…

Driver’s response prediction using Naturalistic Data Set

Ohio State Univ-Dennis Guenther
Ohio State University-Venkata Raghava Ravi Lanka
  • Technical Paper
  • 2019-01-0128
To be published on 2019-04-02 by SAE International in United States
Evaluating the safety of Autonomous Vehicles (AV) is a challenging problem, especially in traffic conditions involving dynamic interactions. A thorough evaluation of the vehicle's decisions at all possible critical scenarios is necessary for estimating and validating its safety. However, predicting the response of the vehicle to dynamic traffic conditions can be the first step in the complex problem of understanding vehicle's behavior. This predicted response of the vehicle can be used in validating vehicle's safety. In this paper, models based on Machine Learning were explored for predicting and classifying driver's response. The Naturalistic Driving Study dataset (NDS), which is part of the Strategic Highway Research Program-2 (SHRP2) was used for training and validating these Machine Learning models. Various popular Machine Learning Algorithms were used for classifying and predicting driver's response, such as Extremely Randomized Trees and Gaussian Mixture Model based Hidden Markov Model, which are widely used in multiple domains. For classifying driver's response, longitudinal acceleration vs lateral acceleration plot (Ax-Ay plot) was divided into nine different classes and selected Machine Learning models were trained…

Constructing a Concept Vehicle Structure Optimized for Crashworthiness

Dassault Systemes Simulia Corp-Shawn Freeman, Fabien Letailleur
Dassault Systemes Simulia Corp.-Yangwook Choi
  • Technical Paper
  • 2019-01-0613
To be published on 2019-04-02 by SAE International in United States
Multi-disciplinary optimization (MDO) of a vehicle structure at the earliest stages of design is critical as OEMs are pressed to reduce the design time to respond to various demands from market. MDO for the three essential areas of performance of the vehicle structure (NVH, Crash, and Durability) needs the throughput for each of the key disciplines to be approximately in the same range of turn-around time. However, crashworthiness simulation typically takes significantly longer than the others; making it difficult to include crashworthiness in the MDO. There have been many approaches to address crash simulation in a shorter time. Lumped mass-spring method is one of the approaches but has not been widely accepted since it did not replicate the crash behavior accurately and it is hard to convert the results into real design of the structural components. In the paper, a workflow is presented to combine the lumped mass-spring method with paramet-ric optimization to provide solutions to the challenges mentioned.

HYDROGEN-DIESEL ENGINE: PROBLEMS AND PROSPECTS OF IMPROVING THE WORKING PROCESS

Bauman Moscow Technical University-Revaz Kavtaradze
Institute of Machine Mechanics-Tamaz Natriashvili
  • Technical Paper
  • 2019-01-0541
To be published on 2019-04-02 by SAE International in United States
The diesel engine with direct injection of hydrogen gas has clear advantages over the hydrogen engine with forced ignition of a hydrogen-air mixture. Despite of this, the concept of hydrogen-diesel engine has not investigated until now. In the paper, a detailed study of the working process of hydrogen-diesel engine carried out for the first time. Based on the results of the experimental studies and mathematical modeling, it has established that the behavior of thermophysical processes in the combustion chamber of hydrogen-diesel engine, in a number of cases, differs fundamentally from the processes that take place in the conventional diesel engines. There have been identified the reasons for their difference and determined the values of the operating cycle parameters of hydrogen diesel engine, which provide the optimal correlation between the indicator values and the environmental performance. For a single-cylinder hydrogen-diesel engine MAN (S/D=300/240 mm/mm) the concentration of nitrogen oxides in combustion products is: [NOx] = 920 ppm, the mean effective pressure pe=9.0 bar, and the indicator efficiency of hydrogen diesel engine ηi=0.48. Overall, it can be…

Effect of Turbulence-Chemistry Interaction on Spray Combustion: a Large Eddy Simulation Study

Dalian University of Technology-Ming Jia
Tianjin University-Junqian Cai, Tianyou Wang, Kai Sun, Zhen Lu, Gang Xiao, Shiquan Shen
  • Technical Paper
  • 2019-01-0203
To be published on 2019-04-02 by SAE International in United States
Although turbulence plays a critical role in engines operated within low temperature combustion (LTC) regime, its interaction with chemistry on auto-ignition at low-ambient-temperature and lean-oxygen conditions remains inadequately understood. Therefore, it is worthwhile taking turbulence-chemistry interaction (TCI) into consideration in LTC engine simulation by employing advanced combustion models. In the present study, large eddy simulation (LES) coupled with linear eddy model (LEM) is performed to simulate the ignition process in n-heptane spray under engine-relevant conditions, known as Spray H. With LES, more details about unsteady spray flame could be captured compared to Reynolds-averaged Navier-Stokes equations (RANS). With LEM approach, both scalar fluctuation and turbulent mixing on sub-grid level are captured, accounting for the TCI. A skeletal mechanism is adopted in this numerical simulation, including 41 species and 124 reactions. Validations is carried out and numerical results show good agreement with experimental data. It is found that, Damköhler number (Da) at the onset of high temperature reaction evidently decreases as ambient temperature and oxygen reduces. Consequently, combustion mode varies from flamelet regime to slow chemistry regime,…

Closed-Form Structural Stress Solutions for Spot Welds in Square Plates under Central Bending Conditions

University of Michigan-Shin-Jang Sung, Jwo Pan
  • Technical Paper
  • 2019-01-1114
To be published on 2019-04-02 by SAE International in United States
A new closed-form structural stress solution for a spot weld in a square thin plate under central bending conditions is derived based on the thin plate theory. The spot weld is treated as a rigid inclusion and the plate is treated as a thin plate. The boundary conditions follow those of the published solution for a rigid inclusion in a square plate under counter bending conditions. The new closed-form solution indicates that structural stress solution near the rigid inclusion on the surface of the plate along the symmetry plane is larger than those for a rigid inclusion in an infinite plate and a finite circular plate with pinned and clamped outer boundaries under central bending conditions. When the radius distance becomes large and approaches to the outer boundary, the new analytical stress solution approaches to the reference stress whereas the other analytical solutions do not. The Mode II stress intensity factor solution based on the new structural stress solution for a rigid inclusion under central bending conditions is improved by up to 3% for similar…

Model Order Reduction for x-In the Loop (xIL) Simulation of Automotive Transmissions

Ohio State University-Clayton Thomas, Punit Tulpule, Shawn Midlam-Mohler
  • Technical Paper
  • 2019-01-1042
To be published on 2019-04-02 by SAE International in United States
Increasing complexity of automotive systems along with growing safety and performance requirements, is causing development cycle costs to swell. A common solution is to use Model Based Design (MBD) approach, particularly use of x-In the Loop (xIL) simulation methods for Validation and Verification (V&V). MBD allows efficient workflow from off-line control design using high fidelity models to a real time V&V using Hardware In the Loop(HIL) simulations. It is very challenging to reduce the complex non-linear high fidelity models to real-time capable models for HIL simulation. Current literature does not provide a standard approach for obtaining the HIL capable reduced model for complex non-linear systems. In this paper we present an approach to perform model reduction in light of HIL level requirements. The approach is presented using an example of a 10 speed automated transmission. The system constitutes three subsystems - the hydraulic network, mechanical gearbox and torque converter. In the first step a high-fidelity model for each subsystem is built up from the component level using one-dimensional mechanics and zero-dimensional hydraulic fluid flow. Secondly,…

Multi-Objective Optimization of Gerotor Port Design by Genetic Algorithm with Considerations on Kinematic vs. Actual Flow Ripple

Purdue University-Andrew Robison, Andrea Vacca
  • Technical Paper
  • 2019-01-0827
To be published on 2019-04-02 by SAE International in United States
Gerotor pumps are common in low pressure automotive applications such as fuel delivery, lubrication, and automatic transmissions. Recent automotive trends, such as electrification, demand these units to perform in more demanding conditions, so modern design methodologies must be developed to meet these challenges. Previous work in gerotor gear geometry design used the kinematic flow ripple as an objective function during extensive profile optimization. Although more sophisticated methods exist for predicting the flow ripple, the kinematic flow ripple was used to reduce the computation time of optimizations. However, compressibility, internal leakages, and throttling effects have an impact on the performance of the pump and cause the flow ripple to deviate from the kinematic flow ripple. As a way to counter this phenomenon, the ports can be designed to account for fluid effects to reduce the outlet flow ripple, internal pressure peaks, and localized cavitation due to throttling while simultaneously improving the volumetric efficiency. The design of the ports is typically heuristic, but a more advanced approach can be to use a numerical fluid model for virtual…

Rapid Optimal Design of a Light Vehicle Hydraulic Brake System

Politecnico di Torino-Pier Giuseppe Anselma, Shirish Padmakar Patil, Giovanni Belingardi
  • Technical Paper
  • 2019-01-0831
To be published on 2019-04-02 by SAE International in United States
Automobile brake system design process is complex and time consuming as there are several components in the system as well as the system has to pass all the conflicting government regulations. With these constraints it is not easy to design an optimal configuration. This paper proposes a simple, intuitive and automated methodology that enables rapid optimal design of light vehicle hydraulic brake systems through an efficient exhaustive search of all the possible designs. Firstly, the system is modeled through cascaded analytical equations for each component. A large design space is then generated by varying the operational parameters of each component in its specific reasonable range. The system components under consideration include the brake pedal, the master cylinder, the vacuum-assisted booster, the brake line and the brake pistons. Successful system configurations are identified by implementing the requirements of the two most relevant safety homologation standards for light vehicle brake systems (US and EU legislations). Ergonomics constraints and the compensation for the fluid losses in the system complete the design requirements. The optimal design identification is carried…