Topic

# Patternation

About: Patternation is a research topic. Over the lifetime, 88 publications have been published within this topic receiving 1003 citations.

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Visteon

^{1}, General Motors^{2}, Ford Motor Company^{3}, Delphi Automotive^{4}, Siemens^{5}, Chrysler Group LLC^{6}, Bosch^{7}TL;DR: The recommended practices in SAE J2715 as discussed by the authors can be used by the spray laboratories of all automotive companies and injectors to obtain accurate and repeatable spray data for a combustion strategy such as gasoline direct injection.

Abstract: With increasingly stringent emissions regulations and concurrent requirements for enhanced engine thermal efficiency, a comprehensive characterization of the automotive gasoline fuel spray has become essential. The acquisition of accurate and repeatable spray data is even more critical when a combustion strategy such as gasoline direct injection is to be utilized. Without industry-wide standardization of testing procedures, large variablilities have been experienced in attempts to verify the claimed spray performance values for the Sauter mean diameter, Dv90, tip penetration and cone angle of many types of fuel sprays. A new SAE Recommended Practice document, J2715, has been developed by the SAE Gasoline Fuel Injection Standards Committee (GFISC) and is now available for the measurement and characterization of the fuel sprays from both gasoline direct injection and port fuel injection injectors. A primary motivation for the development of the standardized procedures for test configuration, data acquisition, data reduction and reporting was to achieve significant reductions in the test-to-test and laboratory-to-laboratory variabilities of such reported spray data. All of the major areas of fuel injector spray testing and characterization are addressed in detail in the document, including spray imaging, high-resolution patternation and drop sizing by both phase-Doppler interferometry and laser diffraction. Valuable lessons regarding the definitions and interpretations of commonly-used spray parameters were learned during the development of the J2715 document, and these are presented and discussed. Based upon the five years of committee discussions and consensus decisions, five key recommendations on fuel spray measurement and characterization are made to the worldwide automotive industry. The first, and most important, recommendation is that the Recommended Practices in SAE J2715 be utilized by the spray laboratories of all automotive companies and injector 2008-01-1068 Gasoline Fuel Injector Spray Measurement and Characterization – A New SAE J2715 Recommended Practice

123 citations

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01 Jan 2009

TL;DR: In this article, a large-eddy simulation of an atomizing spray issuing from a gas-turbine injector is performed, where a Lagrangian point-particle formulation with a stochastic model for droplet breakup is used for the liquid phase.

Abstract: Large-eddy simulation of an atomizing spray issuing from a gas-turbine injector is performed. The filtered Navier–Stokes equations with dynamic subgrid scale model are solved on unstructured grids to compute the swirling turbulent flow through complex passages of the injector. The collocated grid, incompressible flow algorithm on arbitrary shaped unstructured grids developed by Mahesh et al. ( J. Comp. Phys. 197 (2004) 215–240) is used in this work. A Lagrangian point-particle formulation with a stochastic model for droplet breakup is used for the liquid phase. Following Kolmogorov’s concept of viewing solid particle-breakup as a discrete random process, the droplet breakup is considered in the framework of uncorrelated breakup events, independent of the initial droplet size. The size and number density of the newly produced droplets is governed by the Fokker–Planck equation for the evolution of the pdf of droplet radii. The parameters of the model are obtained dynamically by relating them to the local Weber number and resolved scale turbulence properties. A hybrid particle-parcel is used to represent the large number of spray droplets. The predictive capability of the LES together with Lagrangian droplet dynamics models to capture the droplet dispersion characteristics, size distributions, and the spray evolution is examined in detail by comparing it with the spray patternation study for the gas-turbine injector. The present approach is computationally efficient and captures the global features of the fragmentary process of liquid atomization in complex configurations.

52 citations

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15 Jan 1996

TL;DR: In this article, a method is presented to correct for laser sheet extinction effects in performing Planar Liquid Laser Induced Fluorescence (PLLIF) in dense sprays, which assumes only that extinction occurs according to Beer's law.

Abstract: A method is presented herein to correct for laser sheet extinction effects in performing Planar Liquid Laser Induced Fluorescence (PLLIF) in dense sprays. The method involves sequential illumination of the spray by counterpropagating laser sheets, and assumes only that extinction occurs according to Beer's law. Spray symmetry is not jired. The method is experimentally evaluated us ig a hollow cone spray and a flat fan spray. Introduction For non-fluorescing fluids, a means of achieving Planar Liquid Laser Induced Fluorescence (PLLIF), is to dissolve a fluorescent dye in the fluid to be sprayed. When later illuminated as a spray with a laser sheet, the fluorescence intensity distribution can be related to the mass distribution in the plane of the sheet. This "optical patternation" can then be used as an alternative to more intrusive mechanical patternation techniques. In dense sprays, however, secondary scattering can introduce three primary sources of error: (a) extinction of the laser sheet; (b) illumination of particles outside the plane of the sheet by the scattered light and subsequent additional fluorescence from them; and (c) extinction of the fluorescence signal by particles in the path of the detector. A method is presented to correct for the first of these by making quantitative PLLIF measurements independent of laser sheet intensity. This paper is declared a work of the U.S. Government and is not subject to copyright protection in the United States. Outline of the approach To a first approximation, the gray level G registered by a pixel in a CCD array by the PLLIF technique can be related to the laser sheet intensity and the total spray mass per unit volume by the following derivation. Neglecting noise, the gray level in a given pixel will be proportional to the total number of photons received from some small solid angle in the optical field. Ideally, these photons will originate only from the region defined by the intersection of the finite thickness laser sheet with the small solid angle. This intersection defines a small volume element, SV, which can be approximated as the product of a cylinder of length h and cross sectional area 5A, i.e., SV = h6A. The total number of photons emitted from this volume is assumed to be proportional to the camera exposure time (or laser pulse period if that is exposure determining) At, the laser sheet intensity, /, and the average number of fluorescing molecules in 8V during the exposure period. If the dye concentration is constant and uniform (this implies that there is no vaporization), the latter quantity is proportional to the total average amount of liquid mass present at any time, m. An average measure of liquid mass concentration (mass per unit volume) can be defined as ~pm = Sm/SV. If A is sufficiently small and the statistical sample is sufficiently representative of the spray, then p>OT will approximate the true local liquid mass per unit volume, or dispersed phase density, p(x5ty,z), which is related to droplet statistics through the equation pm = p(x,y,z) = $ (1) where D is the droplet diameter, p, is the density of the pure liquid, and n(D\x,y,z) is the droplet size distribution, that is, n(D\x,y,z)dD is the number of droplets per unit volume with diameters between D and D + dD, as a function of position (x,y,z). However, the laser sheet intensity is rarely uniform over the thickness of the sheet. The more usual case is a Gaussian distribution if the original beam is Gaussian. It is then necessary to take into account an intensity distribution I(z), where z is the distance perpendicular to the sheet. Thus, when all of the above factors are considered, the gray level registered by a pixel element can be estimated from

38 citations

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TL;DR: The objective of the research was to understand and improve the unusual physical and atomization properties of the complexes/adhesives derived from the tapioca starch by addition of borate and urea by determining the effect of temperature, shear rate, and mass concentration of thickener/stabilizer on the complex viscosity, density, and surface tension.

Abstract: The objective of the research was to understand and improve the unusual physical and atomization properties of the complexes/adhesives derived from the tapioca starch by addition of borate and urea. The characterization of physical properties of the synthesized adhesives was carried out by determining the effect of temperature, shear rate, and mass concentration of thickener/stabilizer on the complex viscosity, density, and surface tension. In later stage, phenomenological analyses of spray jet breakup of heated complexes were performed in still air. Using a high speed digital camera, the jet breakup dynamics were visualized as a function of the system input parameters. The further analysis of the grabbed images confirmed the strong influence of the input processing parameters on full cone spray patternation. It was also predicted that the heated starch adhesive solutions generate a dispersed spray pattern by utilizing the partial evaporation of the spraying medium. Below 40°C of heating temperature, the radial spray cone width and angle did not vary significantly with increasing Reynolds and Weber numbers at early injection phases leading to increased macroscopic spray propagation. The discharge coefficient, mean flow rate, and mean flow velocity were significantly influenced by the load pressure but less affected by the temperature.

35 citations

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14 Nov 1988

TL;DR: In this article, a process and apparatus are disclosed to form fine patternation and alphanumeric characters of colored cocoa butter in a flush chocolate surface, where a printing sheet defining shallow indentations wherein cocoa butter patternation is deposited by screen printing without disfiguration, and an associated mold plate defining cavities to cast chocolate over the printing sheet indentations.

Abstract: A process and apparatus are disclosed to form fine patternation and alphanumeric characters of colored cocoa butter in a flush chocolate surface. The apparatus provides a printing sheet defining shallow indentations wherein cocoa butter patternation is deposited by screen printing without disfiguration, and an associated mold plate defining cavities to cast chocolate over the printing sheet indentations. The process comprises the steps of (1) screen printing colored cocoa butter in appropriate pattern on the surface of the printing plate indentations; (2) aging the configured cocoa butter; (3) aligning the mold matrices in adjacency with the printing sheet indentations; (4) filling the mold matrices with thermally plasticized settable chocolate; (5) aging the molded chocolate until set; and (6) removing the molded chocolate structure and embedded patternation for further disposition. The process produces well defined embedded patterns on smaller chocolate structures.

34 citations