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Piston Bowl Geometry Effects on Combustion Development in a high-speed light-duty Diesel Engine

Ford Motor Company-Eric Kurtz
Sandia National Laboratories-Stephen Busch, Kan Zha
  • Technical Paper
  • 2019-24-0167
To be published on 2019-08-15 by SAE International in United States
In this work, we studied the effects of piston bowl design on combustion in a light-duty direct-injection diesel engine. Two bowl designs were compared: a conventional, omega-shaped bowl and a stepped-lip piston bowl. Experiments were carried out in the SNL single-cylinder optical engine facility, with a medium-load, mild-boosted operating condition featuring a pilot+main injection strategy. CFD simulations carried out with the FRESCO platform featuring full-geometric modeling of the engine, were validated against measured in-cylinder performance as well as soot natural luminosity images. Differences in combustion development were studied using the simulation results, and sensitivities to in-cylinder flow field (swirl ratio) and injection rate parameters were also analyzed. In-cylinder mixture formation analysis showed that ignition of the pilot injection mixture develops nearly as a homogeneous adiabatic reactor, being mostly advected, not mixed, by the bowl’s swirling motion, while its timing is influenced by the local flow field. Local in-cylinder flow is also more crucial than injection parameters to igniting the main injection’s premixed fuel, as it determines the relative overlap with the high-temperature pilot ignited mixture.…
 
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Optimal Pressure Relief Groove Geometry for Improved NVH Performance of Variable Displacement Oil Pumps

Ford Motor Company-Abdelkrim Zouani, Vidya Marri
Published 2019-06-05 by SAE International in United States
Variable Displacement Oil Pump (VDOP) is becoming the design of choice for engine friction reduction and fuel economy improvement. Unfortunately, this pump creates excessive pressure ripples, at the outlet port during oil pump shaft rotation, causing oscillating forces within the lubrication system and leading to the generation of objectionable tonal noises and vibrations. In order to minimize the level of noise, different vanes spacing and porting geometries are used. Moreover, an oil pressure relief groove can be added, at the onset of the high pressure port, to achieve this goal.This paper presents an optimization method to identify the best geometry of the oil pressure relief groove. This method integrates adaptive meshing, 3D CFD simulation, Matlab routine and Genetic Algorithm based optimization. The genetic algorithm is used to create the required design space in order to perform a multi-objective optimization using a large number of parameterized groove geometries. Results of this optimization method are discussed and a design guideline for the oil pressure relief groove is disclosed.
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Target Development for Transmission and Electric Motor NVH

Ford Motor Company-Justin Dech, Frederick Vanhaaften, Matthew Hettenhouse
FEV North America, Inc.-Todd Tousignant, Alex Ford, Kiran Govindswamy
Published 2019-06-05 by SAE International in United States
It is a common practice to conduct NVH fingerprinting and benchmarking assessments at the powertrain level, to understand source level noise and vibration. To assess the NVH influence of engine, e-motor, and transmission, sub-system testing is often conducted in addition to full powertrain testing. These powertrain or sub-system investigations provide valuable information regarding the status of “source” level excitations relative to targets and / or competitive powertrains. In the case of transmissions and e-machines, it is particularly important to understand source level tonal content and how this will be perceived at the vehicle level. However, variation in component design results in differences in order content, which complicates the process of objectively comparing multiple products.Multiple methods are presented here for characterizing tonal content of transmission and e-machines, based on assessments conducted in a component hemi-anechoic dynamometer test cell. Ultimately, sound quality is assessed by the customer at the vehicle level. Accordingly, the methods developed incorporate means of cascading results between component level and vehicle level. Furthermore, since the perception of tonal noise content is dependent upon…
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Augmenting Vehicle Production Audit with Objective Data and Sound Quality Metrics to Improve Customer Experience in a Changing Automotive Landscape

Ford Motor Company-Mark Sturgill
Bruel & Kjaer Sound and Vibration A/S-Brian Thom, Gabriella Cerrato
Published 2019-06-05 by SAE International in United States
Vehicle manufacturers face increasing challenges in auditing the build quality of their vehicles while considering increasing consumer demands regarding NVH performance. This effect is compounded with the rise in electric and hybrid vehicles. The ability to audit vehicles for a variety of noise types is becoming increasingly important; these include powertrain noise, road noise, and wind noise. An automated measurement system was developed with specific algorithms and sound quality metrics to not only audit vehicle production quality but to add objective data, pass-fail criteria, and trend analysis.
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Turbocharger Centrifugal Compressor Casing Treatment for Improved BPF Noise Using Computational Fluid Dynamics

Ford Motor Company-Ahsanul Karim, Chris Tiernan, Keith Miazgowicz, Ted Mull
Ford Powertrain Operations-Anthony Morelli
Published 2019-06-05 by SAE International in United States
The conventional ported shroud recirculation casing treatment elevates narrowband noise at blade pass frequency. A new ported shroud recirculating casing treatment was implemented in Ford’s 3.5L turbo gas engine as Noise Vibration and Harshness (NVH) counter measure to reduce whoosh (broadband flow noise) noise without elevating narrowband noise at blade pass frequency. The new ported shroud design incorporates holes between the main and secondary recirculating passage and a slight cross-sectional area reduction just upstream of the impeller. These design features reduce whoosh noise without elevating the first order and the sixth order tonal noise at blade pass frequency. The new ported shroud design decreases narrowband tonal noise sound pressure level by 3-6 dB in the low to mid flow region compared to the baseline design. Computational Fluid Dynamics (CFD) tools were used to develop this casing treatment design.
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Surge Prediction in a Single Sequential Turbocharger (SST) Compressor Using Computational Fluid Dynamics

Ford Motor Company-Ahsanul Karim, Robert Wade, Keith Miazgowicz, Brian Lizotte
Ford Powertrain Operations-Anthony Morelli
Published 2019-06-05 by SAE International in United States
The Single Sequential Turbocharger (SST) used in Ford’s 6.7L Scorpion Diesel is analyzed using Computational Fluid Dynamics (CFD) to draw conclusions about the compressor stability at low mass flows. The SST compressor concept consists of a double-sided wheel which flows in parallel fed by two separate inlets (front and rear), followed by a single vane-less diffuser, and a volute. CFD simulations for the full stage are performed at low mass flow rates Both, front and rear, sides have ported shroud casing-treatment (CT) in the inlet region. An objective of the analysis is to determine which side of the SST unit compressor (front or rear on the double-sided wheel) suffers flow break down first as the mass flow is reduced, and its impact on the overall stability of the SST compressor. Another objective is to better understand the interactions between the compressor inlet flow and the flow through the casing-treatment. It has been observed that these interactions reduce the effectiveness of the front ported shroud casing-treatment in the selected geometry. This leads to a breakdown of…
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Integrated Multi-Physics Simulation for Full-Vehicle Low Frequency NVH Optimization in HEVs

Ford Motor Company-Jack Liu
Gamma Technologies LLC-Llorenc Foraste Gomez, Jonathan Zeman
Published 2019-06-05 by SAE International in United States
The recent automotive industry trend towards electrification has created new challenges for NVH engineers. These challenges stem from new powertrain architectures and their complex interactions, the governing control strategies which aim to optimize energy management, and new unmasked sources of excitation. Additionally, vehicle manufacturers are attempting to reduce hardware testing in order to rapidly satisfy increasing production demand and to minimize its costs. Hence, to meet the above-mentioned challenges up front in the development process of Hybrid Electrical Vehicles (HEVs) while balancing competing design objectives of drivability, durability and NVH, a simulation-led design and optimization is required.NVH problems are often the result of mechanisms that originate through complex interactions between different physical domains (flow, electromagnetic, structural/mechanical, control logic, etc.) and the assembly of individual components into a complete system. Therefore, accurate system-level integrated models are becoming a requirement to solve modern NVH problems.Combining the optimal balance between simulation and experimental data, this article describes a joint effort between Ford and Gamma Technologies to develop a general methodology to perform full-vehicle low frequency NVH analysis. Using…
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Testing Methods and Signal Processing Strategies for Automatic Transmission Transient Multiplexed Pressure Data

Ford Motor Company-Steve Frait, Ram Sudarsan Devendran
Michigan Technological University-Mark Woodland, Jason Blough, Darrell Robinette, Carl Anderson
Published 2019-06-05 by SAE International in United States
Transmissions have multiple transient events that occur from gear shifting to torque converter clutch application. These transients can be difficult to capture and observe. A six speed front wheeled drive transmission was instrumented with pressure transducers to measure clutches and the torque converter. Due to size restrictions internal to the torque converter the data had to be multiplexed across three different transmitters. A method to capture a transient event through the use of multiplexed data was developed to create a data set with the transient event occurring on each channel. Once testing is completed, the data has to be split into individual channels and synced with the operational data. The data then can be used in both time and frequency domain analysis. It is important to understand that the data is not continuous and must be taken into consideration when post processing it for further results.
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Machine Learning Algorithm for the Prediction of Idle Combustion Uniformity

Xiaoqi Li
Ford Motor Company-Abdelkrim Zouani
Published 2019-06-05 by SAE International in United States
Combustion stability is a key contributor to engine shake at idle speed and can impact the overall perception of vehicle quality. The sub-firing harmonics of the combustion torque are used as a metric to assess idle shake and are, typically, measured at different levels of engine break mean effective pressure (BMEP). Due to the nature of the combustion phenomena at idle, it is clear that predicting the cycle-to-cycle and cylinder-to-cylinder combustion pressure variations, required to assess the combustion uniformity, cannot be achieved with the state of the art simulation technology.Inspired by the advancement in the field of machine learning and artificial intelligence and by the availability of a large amount of measured combustion test data, this paper explores the performance of various machine learning algorithms in predicting the idle combustion uniformity. The algorithms that are explored include Neural Network (NN), Support Vector Machine (SVM), Ensembles of Trees (EOT) and Gaussian Process (GP). The variables selected as inputs to these algorithms include BMEP, indicated mean effective pressure (IMEP), pumping mean effective pressure (PMEP), spark timing, crank…
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Improved Analytically Derived CO2 Prediction of Medium Duty Chassis-Certified Vehicles

Ford Motor Company-Mrudula Orpe, Thomas Megli, Patrick Phlips, William Ruona, Donnell Washington II
Published 2019-04-02 by SAE International in United States
Medium duty vehicles come in many design variations, which makes testing them all for CO2 impractical. As a result there are multiple ways of reporting CO2 emissions. Actual tests may be performed, data substitution may be used, or CO2 values may be estimated using an analytical correction. The correction accounts for variations in road load force coefficients (f0, f1, f2), weight, and axle ratio. The EPA Analytically Derived CO2 equation (EPA ADC) was defined using a limited set of historical data. The prediction error is shown to be ±130 g/mile and the sensitivities to design variables are found to be incorrect. Since the absolute CO2 is between 500 and 1,000 g/mi, the equation has limited usefulness. Previous work on light duty vehicles has demonstrated a linear relationship between vehicle fuel consumption, powertrain properties and total vehicle work. This relationship improves the accuracy and avoids co-linearity and non-orthogonality of the input variables. The proposed equation reduces the prediction error to ± 35 g/mile and gives correct sensitivities to design parameters.
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