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Technical Paper

A Non-Contact Technique for Vibration Measurement of Automotive Structures

2019-06-05
2019-01-1503
The automotive and aerospace industries are increasingly using the light-weight material to improve the vehicle performance. However, using light-weight material can increase the airborne and structure-borne noise. A special attention needs to be paid in designing the structures and measuring their dynamics. Conventionally, the structure is excited using an impulse hammer or a mechanical shaker and the response is measured using uniaxial or multi-axial accelerometers to obtain the dynamics of the structure. However, using contact-based transducers can mass load the structure and provide data at a few discrete points. Hence, obtaining the true dynamics of the structure conventionally can be challenging. Thus, researchers and test engineers seek for non-contact measurement techniques that do not induce mass loading effects and provide full field response.
Technical Paper

Driveline NVH integration of A NA truck program

2019-06-05
2019-01-1559
In current automotive industry, it is well known that the driveline subsystem and components are normally from different automotive suppliers for OEMs. In order to ensure proper system integration and successful development of driveline system NVH performances, collaboration efforts between OEMs and suppliers are very demanding and important. In this paper, a process is presented to achieve successfulness in developing and optimizing vehicle integration through effective teamwork between a driveline supplier and a major OEM. The development process includes multiple critical steps. They include target development and roll down, targets being specific and measurable, comprehension of interactions of driveline and vehicle dynamics, accurate definition of sensitivity, proper deployment of modal mapping strategy, which requires open data sharing; and system dynamics and optimization.
Technical Paper

Experimental Investigation of the Bi-stable Behavior in the Wake of a Notchback MIRA Model

2019-04-02
2019-01-0663
This paper reports an experimental investigation of the wake flow behind a 1/12 scale notchback MIRA model at Re=UL/ν=6.9×10^5(where U is free-stream velocity, L the length of the model and ν viscosity). Focus was placed on the flow asymmetry over the rear window and trunk of a notchback MIRA model. One hundred and three measurement points were used to map the pressure field, while the wake topology was investigated by means of 2D Particle Image Velocimetry. The analysis of the instantaneous pressure signals over the notch configuration clearly shows that the wake presents a bi-stable behavior in the horizontal direction, characterized by the switches between two preferred positions leading to a statically symmetric wake, but this phenomenon is not found in the vertical direction. The instantaneous wake dynamic highlights three forms that correspond to two bi-stable states and switch state respectively, confirming the analysis result of the instantaneous pressure signals.
Technical Paper

Optimisation of Image Processing Parameters for Flame Image Velocimetry (FIV) Measurement in a Single-Cylinder, Small-Bore Optical Diesel Engine

2019-04-02
2019-01-0719
High-speed soot luminosity movies are widely used to visualise flame development in optical diesel engines due to its simple setup and relatively low cost. Recent studies demonstrated the high-speed soot luminosity movies are not only effective in showing the overall distribution and temporal evolution of sooting flames but also flow fields within the flame through the application of combustion (or flame) image velocimetry. The present study aims to improve this imaging technique by systematically evaluating key image processing parameters based on high-speed soot luminosity movies obtained from a single-cylinder, small-bore optical diesel engine. The raw luminosity movies are processed in PIVlab – a Matlab-based open-source code widely used for particle image velocimetry (PIV) applications.
Technical Paper

Novel Metrics for Validation of PIV and CFD in IC Engines

2019-04-02
2019-01-0716
In-cylinder flow motion has a significant effect on mixture preparation and combustion. Therefore, it is vital that CFD engine simulations are capable of accurately predicting the in-cylinder velocity fields. High-speed planar Particle Image Velocimetry (PIV) experiments have been performed on a single-cylinder GDI optical engine in order to validate CFD simulations for a range of engine conditions. Novel metrics have been developed to quantify the differences between experimental and simulated velocity fields in both alignment and magnitude. The Weighted Relevance Index (WRI) is a variation of the standard Relevance Index that accounts for the local velocity magnitudes to provide a robust comparison of the alignment between two vector fields. Similarly, the Weighted Magnitude Index (WMI) quantifies the differences in the local magnitudes of the two velocity fields.
Technical Paper

Effects of the Wet Retroreflectivity and Luminance of Pavement Markings on Lane Departure Warning in Nighttime Continuous Rain with and without Glare Sources

2019-04-02
2019-01-1014
A common challenge for both machine vision (MV) systems based on visible-spectrum cameras and for human drivers is detection of pavement markings in nighttime rainy conditions. This occurs because a layer of water refracts the light differently than air, causing conventional markings to substantially retroreflect the light away from the driver or camera when the marking is immersed. This reduces the marking retroreflectivity in wet conditions, and thus the contrast in the image collected by the camera at longer viewing distances. MV lane departure warning (LDW) systems also depend on pixel data from shorter viewing distances; the contrast here also depends on the luminance (Cap Y (CIE)) of the marking, which typically is reduced if the marking is soiled or worn.
Technical Paper

Calibration and Stitching Methods of the Around View Monitor System of Articulated Multi-Carriage Road Vehicle for Intelligent Transportation

2019-04-02
2019-01-0873
The Around View Monitor (AVM) system of the long-body road vehicle with multiple articulated carriages usually suffers from the incomplete distortion correction of fisheye cameras on the side of the coach and the irregular image stitching area caused by the change of relative position of the cameras on different carriages while the vehicle is in motion. In response to these problems, a set of calibration and stitching methods of AVM are proposed. When the system is in the calibration mode, first a two-step optimization method is adopted to solve the polynomial radial distortion-based fisheye camera model. Then, a robust corner detection technique is proposed to extract all the chessboard corners and square vertexes in the system calibration scene. With the calibrated camera model and geometric information of the mounted system, the initial look-up table from the fisheye images to a top view of the vehicle is extrapolated.
Technical Paper

Security in Wireless Powertrain Networking through Machine Learning Localization

2019-04-02
2019-01-1046
This paper demonstrates a solution to the security problem for automotive wireless powertrain networking. That is, the security for wireless automotive networking requires a localization function before we allow a node to join the network. We explain why for powertrain wireless networking, this ability of identifying the precise location of a communicating wireless node is critical. In this paper, we explore existing methods that others have used to implement localization for wireless networking. Then, we apply machine-learning techniques to a dataset that has localization information associated with received signal strength indication. We reveal insights provided by our dataset though an exploration with statistics and visualization. We then present our problem in terms of pattern recognition via multiple techniques, including Naïve Bayes Classifier and Artificial Neural Networks.
Technical Paper

Optical experiments on strong knocking combustion in rapid compression machines with different fuels

2019-04-02
2019-01-1142
Knocking combustion has become the greatest bottleneck of internal combustion engines with advanced combustion technologies for pursuing thermal efficiency limits. Because of the complexities of combustion conditions, the mechanism for strong knocking combustion in engines under different combustion modes is still not fully understood. In this study, synchronization measurement through simultaneous pressure acquisition and high-speed direct photography was performed, and strong knocking combustion for premixed iso-octane/air mixture was studied in a high-strength optical rapid compression machine with flat piston design. First, strong knocking phenomena under both spark-ignition and compression-ignition conditions are identified through varying initial thermodynamic conditions.
Technical Paper

Multi-wavenlengths Michelson interferometer based spatial phase shift shearography with color camera

2019-04-02
2019-01-1269
The laser interferometric, optical full-field measurement method of digital shearography (DS) has already established for industrial NDT applications. The method with spatial phase shift (SPS), which can now be used qualitatively for the first time, allows the necessary phase information to be ob-tained in the video sequence, making dynamic investigations possible. SPS is linked to a reduced quality of the result, which is now largely compensated by the current state of camera technology. The simple, stable and cost-effective realization of SPS-DS using the carrier frequency method on the Michelson interferometer is particularly suitable for industrial use. The design can easily be ex-tended by a 4f system, allowing even large measuring areas to be inspected. In addition, applications with multi-wavelength illumination were implemented with the aim of recording the entire three-dimensional object deformation in the video sequence.
Technical Paper

Effect of Injection Pressure on Nozzle Internal Flow and Jet Breakup under Sub-Cooled and Flash Boiling Test Conditions

2019-04-02
2019-01-0286
Injection pressure plays a vital role in spray break-up and atomization. High spray injection pressure is usually adopted to optimize the spray atomization in gasoline direct injection fuel system. However, higher injection pressure also leads to engine emission problem related to wall wetting. To solve this problem, researchers are trying to use flash boiling method to control the spray atomization process under lower injection test conditions. However, the effect of injection pressure on the spray atomization under flash boiling test condition has not been adequately investigated yet. In this study, quantitative study of internal flow and near nozzle spray breakup were carried out based on a two-dimensional transparent nozzle via microscopic imaging and phase Doppler interferometery. N-hexane was chosen as test fluid with different injection pressure conditions. Fuel temperature varied from 112°C to 148°C, which covered a wide range of superheated conditions.
Technical Paper

Nozzle Flow Simulation of GDi for Measuring Near-Field Spray Angle and Plume Direction

2019-04-02
2019-01-0280
Experimental visualization of current gasoline direct injection (GDi) systems are even more complicated especially due to the proximity of spray plumes and the interaction between them. Computational simulations may provide additional information to understand the complex phenomena taking place during the injection process. Nozzle flow simulations with a Volume-of-Fluid (VOF) approach can be used not only to analyze the flow inside the nozzle, but also the first 2-5 mm of the spray. A methodology to obtain plume direction and spray angle from the simulations is presented. Results are compared to experimental data available in the literature. It is shown that plume direction is well captured by the model, whilst the uncertainty of the spray angle measurements does not allow to clearly validate the developed methodology.
Technical Paper

Imaging of Fuel-Film Evaporation and Combustion in a Direct-Injection Model Experiment

2019-04-02
2019-01-0293
Late-evaporating liquid fuel films within the combustion chamber are considered a major source of soot in gasoline direct-injection engines. In this study a direct-injection model experiment was developed to visualize and investigate the evaporation of fuel films and their contribution to soot formation with different diagnostic techniques. A mixture of isooctane (surrogate fuel) and toluene (fluorescent tracer) is injected by a multi-hole injector into a wind tunnel with an optically accessible test section. Air flows continuously at low speed and ambient pressure through the test section. Some of the liquid fuel impinges on the quartz-glass windows and forms fuel films. Combustion is initiated by a pair of electrodes within the fuel/air-mixture. The turbulent flame front propagates through the chamber and ignites pool fires near the fuel films, leading to locally sooting combustion.
Technical Paper

Study of Flash Boiling Spray Combustion in a Spark Ignition Direct Injection Optical Engine Using Digital Image Processing Diagnostics

2019-04-02
2019-01-0252
Flash boiling spray has been proven to be a useful method in providing finer fuel droplet and stronger evaporation in favor of creating a homogeneous fuel-air mixture. Combustion characteristics of flash boiling spray are thus valuable to be investigated systematically for aiding the development of efficient internal combustion system. An experimental study of flash boiling spray combustion in a SIDI optical engine under early injection has been conducted. The fuel, Iso-octane, was used across all tests. Three fuel spray conditions experimented in the study: normal liquid, transitional flash boiling and flare flash boiling sprays, within each case that Pa/Ps ratio was set in (>1), (0.3~1), and (<0.3) respectively. A small quartz insert on the piston enables optical access for observing combustion process; non-intrusive measurements on flame radicals has been carried out using a high-speed color camera.
Technical Paper

Visualization and Analysis of Gaseous Jet Process for an Outward-Opening Nozzle

2019-04-02
2019-01-0275
In this article, the effects on the jet process of natural gas through an outward-opening nozzle were analyzed at different pressure ratios (PR). The visualization and analysis of the jet process was based on Schlieren methods. High-speed Schlieren imaging was used to capture the growth of the transient gas jet in a constant volume vessel (CVV) under atmospheric conditions. The experimental results revealed an increase in the radial and axial penetrations in accordance with an increase in the PR. The jet process of the outward-opening nozzle can be divided into two stages, according to the ratio of the radial penetration to the axial penetration. The spread angle increased with the advancement of the gas jet at the initial phase of the jet process. After this phase, the spread angle decreased to a constant value. The appearance of the constant value is directly related to the PR. The peak velocity increased with an increase in the PR.
Technical Paper

Evaluation of Navigation in Mobile Robots for Long-Term Autonomy in Automotive Manufacturing Environments

2019-04-02
2019-01-0505
Thus far, the focus of autonomous mobile robot researchers has been primarily on developing the functionality and optimizing its performance. In recent times, a number of reference implementations of Simultaneous Localization and Mapping (SLAM) and navigation techniques have been made publicly available via the ROS Community. Several implementations have transitioned to commercial products (vacuum robots, drones, warehouse robots, etc.). However, in such cases, in being specialized and optimized for their specific domains of deployment, they became a “black box”. In particular, their success criteria have been based primarily on mission completion and safety of humans around them. In this light, deployment in any new operational design domain (ODD) requires at least a careful verification of performance and often re-optimization. We seek the technological gaps that need to be addressed to ensure the mobile robots are fit for automotive manufacturing environments.
Technical Paper

Geometric Description of the Soot Cake in a One-Dimensional Model of an Octo-Square Asymmetric Particulate Filter

2019-04-02
2019-01-0991
Asymmetric particulate filters (PF), where the inlet channel is wider than the outlet channel, are commonly used because of their greater ash capacity. Surprisingly, very few models for asymmetric PFs have been published. This paper considers how to model the soot cake in octo-square asymmetric PFs. Some previous studies have neglected the octahedral shape of the inlet channel and instead erroneously assumed that the inlet channels were square. As the correct approach for modelling the soot cake is not obvious, three options are considered. The calculation of soot-loaded channel perimeter and hydraulic diameter (which are important for heat and mass transfer), soot thickness and backpressure as a function of soot loading are given for each geometry. In option 1, the shape of the soot-loaded channel is assumed to be geometrically similar to the soot-free channel.
Technical Paper

Color and Height Characteristic of Surrogate Grass for the Evaluation of Vehicle Road Departure Mitigation System

2019-04-02
2019-01-1026
New vehicles equipped with roadway departure mitigation (RDM) systems have been introduced to the market in recent years. An earlier study showed that 56% of road edges in the U.S are grass. To support the standard objective evaluation of RDM system performance, the development of surrogate road edge grass with the representative property of real grass from the view of automotive sensors is needed. This paper is to describe the process for determining the color and height requirements of surrogate grass for a camera sensor. 824,957 road locations in the U.S. were randomly sampled. Then a stratified sub-sampling was conducted with the balancing consideration, which includes the geographic locations, road levels, and population densities. Finally, 901 randomly selected Google street-view images with grass road edges but without road markings or with poor road markings were gathered and analyzed.
Technical Paper

Generation and Oxidation of Soot Due to Fuel Films Utilizing High Speed Visualization Techniques

2019-04-02
2019-01-0251
For a better understanding of how soot is generated due to fuel films, a constant volume vessel was used together with four visualization techniques due to their high spatial (2D) and time resolution: Schlieren, natural luminosity, diffused back illumination and OH* chemiluminescence. The analysis was performed keeping the injection pressure at 30 bar and changing the plate temperature on which the spray impacts: 80, 120, 160 and 200 °C. The fuel is a mixture of iso-octane, hexane, toluene and 1-methylnaphthalene, which presents similar properties to commercial gasoline. Valuable insights were gained from the results that infer the real nature of the radiation observed during combustion events in gasoline direct injection (GDI) engines due to the presence of a fuel films which are conventionally described as “pool fires”. The results show that the highest quantity of soot is generated between plate temperatures of 80 and 120 °C.
Technical Paper

Internal fuel flow, near-field and far-field spray evolution, and mixture formation characteristics of diesel injectors - a comparison between multi- and single-hole injectors

2019-04-02
2019-01-0273
A comparison of spray characteristics was conducted between single- and multi-hole injectors. Both macroscopic and microscopic imaging was applied to observe the penetration, the spray angle, and the dispersion (spray cone) angle at the vicinity of the nozzle. Simulations using a commercial software (AVL FIRE) was conducted to reveal the internal flow inside the sac volume. Laser absorption scattering (LAS) technique was implemented for measuring the mixture concentration. The vapor penetration was greater for single-hole than that of multi-hole due to faster pressure build-up process inside the sac volume. The dispersion angle was higher for multi-hole injector than that of single-hole during the transient period, due to higher radial velocity term at the nozzle exit induced by the turbulent internal flow.
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