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    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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    <language>en-us</language>
    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
      <url>https://trid.trb.org/Images/PageHeader-wTitle.jpg</url>
      <link>https://trid.trb.org/</link>
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    <item>
      <title>Experimental study on the cavity evolution characteristics of the cylinder passing through the ice plate</title>
      <link>https://trid.trb.org/View/2608989</link>
      <description><![CDATA[This study experimentally investigates the vertical penetration of the cylinder through ice into water at different velocities using high-speed photography. The dynamic process was recorded, and image processing techniques were employed to extract parameters such as velocity of the cylinder, displacement, cavity evolution, and ice fragmentation morphology. The results revealed that the ice plate constrained cavity morphology and dimensions, The ice plate fragmentation process consumes the initial kinetic energy of the cylinder, reduces the initial expansion energy of the cavity, and forces the cavity to enter the collapse stage prematurely. The three-phase mixture (ice-water-air clusters) generated during ice penetration disrupted flow stability, accelerated cavity collapse, and exacerbated angular deflection and velocity attenuation. The crushed ice particles from ice plate fragmentation form a localized blocking effect in the low-pressure region at the tail of the cavitation bubble, and their collision with the cavity walls induces energy dissipation and localized rupture. Notably, with the increasing velocity progressively diminished the ice influence on cavity evolution and motion stability. The cavity evolution gradually approaches the characteristics of ice-free conditions, exhibiting enhanced integrity and reduced disturbances in the trailing wake. This demonstrates that hydrodynamic stability under high-speed conditions can effectively suppress the interference effects induced by the ice layer. Deflection of the cylinder angles decreased with higher velocities, and ice-induced velocity attenuation weakened significantly at elevated speeds. The research findings reveal the multiple influencing factors of cavity evolution under ice layer constraints, providing a theoretical basis for optimizing the water entry process of polar equipment.]]></description>
      <pubDate>Fri, 05 Dec 2025 14:08:32 GMT</pubDate>
      <guid>https://trid.trb.org/View/2608989</guid>
    </item>
    <item>
      <title>Measuring Rebound and Evaluating Pile Resistance During Installation Using Ultra-High Speed/Resolution Photogrammetry</title>
      <link>https://trid.trb.org/View/2553997</link>
      <description><![CDATA[The primary objectives of the study are: (1) provide equipment capable of monitoring pile rebound accurately, improving estimates of pile resistance and increasing safety during pile driving operations, and (2) evaluate the possibility of estimating pile resistance using high-speed cameras.]]></description>
      <pubDate>Fri, 16 May 2025 07:26:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/2553997</guid>
    </item>
    <item>
      <title>Direct Fuel Injector Temporal Measurements</title>
      <link>https://trid.trb.org/View/1830485</link>
      <description><![CDATA[The objective of this study is to measure high-frequency, short-duration, actual liquid fuel spray events using a simple photo detector and validate the results with high-speed camera measurements. This paper presents an optical approach for detecting bulk fuel injection's temporal characteristics, i.e., opening delay and duration times. A key component in the measurement system is a commercially available low-cost photo detector which is shown to be highly effective for detecting high frequency, short duration spray events. The paper provides an in-depth discussion of a photo detector based measurement system, a test fixture, and its validation. Test results with a two-stage pulse-width-modulation (PWM) current controlled approach are provided for various operation parameter settings. Its effectiveness is validated by comparing with the results obtained with a high-speed camera.]]></description>
      <pubDate>Mon, 25 Apr 2022 10:05:24 GMT</pubDate>
      <guid>https://trid.trb.org/View/1830485</guid>
    </item>
    <item>
      <title>Influence of Fuel Volatility on Evaporation Characteristics of Diesel Sprays in Various Low Temperature and Low Density Surrounding Conditions Like at Early Pilot or Late Post Injections</title>
      <link>https://trid.trb.org/View/1833564</link>
      <description><![CDATA[The diesel spray characteristics in early pilot and late post fuel injections in a constant volume chamber which can create the in-cylinder conditions of a diesel engine were visualized with high-speed video. At the early pilot and late post fuel injection, there was a longer penetration of the liquid phase fuel spray as well as slower evaporation. With normal heptane the impingement of liquid spray with early pilot and post fuel injections can be avoided due to a faster evaporation. The penetration of liquid phase fuel spray increases significantly at low IMEP and late post injection conditions with diesel fuel.]]></description>
      <pubDate>Tue, 22 Feb 2022 10:28:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1833564</guid>
    </item>
    <item>
      <title>Characteristics of Nozzle Internal Flow and Near-Field Spray of Multi-Hole Injectors for Diesel Engines</title>
      <link>https://trid.trb.org/View/1833547</link>
      <description><![CDATA[The combustion process, emission formation and the resulting engine performance in a diesel engine are well known to be governed mainly by spray behaviors and the consequent mixture formation quality. One of the most important factors that affect the spray development is the nozzle configuration. Originally, single-hole diesel injector is usually applied in fundamental research to provide insights into the spray characteristics. However, the spray emerging from a realistic multi-hole injector approaches the practical engine operation situation better. Meanwhile, previous research has shown that the reduced nozzle hole diameter is effective for preparing more uniform mixture. In the current paper, a study about the effects of nozzle configuration and hole diameter on the internal flow and spray properties was conducted in conjunction with a series of experimental and computational methods. Two multi-hole nozzles (10 holes) with different hole diameter (D=0.10 mm and 0.07mm) and another two referential single-hole nozzles were applied in Mie-scattering experiments. High-speed images of sprays from each nozzle were freeze-captured at 10000 and 100000 frames per second under the condition of 2.0 mm3/hole injection quantity, 120 MPa injection pressure, 1.5 MPa ambient pressure, room temperature, and air environment. The experimental results revealed that under D=0.10 mm condition, the multi-hole nozzle had lower injection rate, longer injection duration, shorter spray tip penetration, and wider spray angle and spray cone angle compared to those of the single-hole nozzle. However, under D=0.07 mm condition, the differences of injection rate, injection duration, spray tip penetration, and spray angle between two nozzles were quite small, although multi-hole nozzle still had a little wider spray cone angle. Moreover, aiming to correlate the observed spray characteristics to the internal flow phenomenon, CFD simulation was also conducted under the same condition, which provided additional explanations for the spray behaviors.]]></description>
      <pubDate>Tue, 22 Feb 2022 10:28:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/1833547</guid>
    </item>
    <item>
      <title>Proposal of Depth Estimation Method Using Deep Learning for Droplet Visualization</title>
      <link>https://trid.trb.org/View/1882955</link>
      <description><![CDATA[In the Urea-SCR system, two-dimensional visualization images of spray droplet taken by a high-speed camera are used for verification of atomization and measurement of droplet diameter. This paper describes the method for predicting the droplet diameter from visualization image with depth of field using deep learning to improve accuracy of measuring droplet size distribution. As a result from trained model, this method showed applicability to measure droplet within various depths.]]></description>
      <pubDate>Fri, 12 Nov 2021 17:23:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/1882955</guid>
    </item>
    <item>
      <title>Study on the Primary breakup of Fuel Spray in Multi-hole Injector for Direct Injection Gasoline engines</title>
      <link>https://trid.trb.org/View/1867230</link>
      <description><![CDATA[In recent years, Computational Fluid Dynamics (CFD) has been widely used in engine development, and it is known that the accuracy of the droplet breakup model has a great influence on the modeling of fuel sprays in CFD. In this laboratory, WAVE-MTAB model is used as a droplet breakup model for gasoline spray and its applicability is verified. However, WAVE-MTAB model was developed for diesel sprays, and it is reported to have limitations in its applicability to gasoline engines that inject relatively low pressure fuel. The purpose of this study is to elucidate the primary breakup form of the fuel spray in the multi-hole injector for direct gasoline injection, and to develop a breakup model that corresponds to the actual phenomenon. In order to visualize the primary breakup process of the fuel spray under low injection pressure conditions, the authors took enlarged images of the spray near the nozzle hole using a high-speed camera and microscope lens.]]></description>
      <pubDate>Mon, 27 Sep 2021 09:45:51 GMT</pubDate>
      <guid>https://trid.trb.org/View/1867230</guid>
    </item>
    <item>
      <title>Effects of nozzle hole configuration of a multi-hole type gasoline direct injector on spray development under flash boiling conditions</title>
      <link>https://trid.trb.org/View/1866112</link>
      <description><![CDATA[The flash boiling phenomenon is critically affected by not only injection conditions such as fuel temperature, ambient pressure and physical properties of fuel but also the nozzle hole configurations of the injector. In this research, two kinds of injectors, having different nozzle hole configurations (a closed type and a opened type) were used to analyze the influence of flash boiling. Near-field and far-field spray visualization was performed using a high-speed camera based on the Mie-scattering imaging technique. Test parameters were injection pressure, ambient pressure, and fuel temperature. The spray length, spray width, length-to-width ratio, and axial velocity of spray development depending on time were measured using the MATLAB program for quantitative and objective analysis. Finally, the prediction equation for the spray length was derived using the least-squares method based on the experimental results. In the case of the closed type injector, the spray center contained a wide overlapped region because of the strong links between plumes. On the other hand, with the opened type injector, there was a relatively narrow overlapped region between plumes due to weak interaction between plumes. As a result, the closed type injector had a narrow and long spray structure and the opened type injector had a partially long and wide spray structure. According to the prediction equation, the spray develops depending on time more linearly under flash boiling conditions than under non-flash boiling conditions. The influence of flash boiling was smaller in the closed type injector because the closed type injector has less variation of the spray structure with varying injection conditions, ranging from non-flash boiling conditions to non-flash boiling conditions.]]></description>
      <pubDate>Mon, 27 Sep 2021 09:45:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/1866112</guid>
    </item>
    <item>
      <title>Observations of Inversed-delta Fuel Injection Rate Diesel Combustion</title>
      <link>https://trid.trb.org/View/1846392</link>
      <description><![CDATA[The characteristics of diesel fuel spray are very important for diesel ignition and combustion process affecting significantly on engine performance and exhaust emissions. In this study, using the constant volume vessel, which can simulate the gas temperature and pressure at the time of the fuel injection in the direct injection diesel engine, and a high-speed video camera, the observations of diesel fuel spray and combustion process have been made. In the experiments, the injection system having a direct-acting piezo-actuator was used to get arbitrary injection rate profiles which cannot be realized with conventional injection system. This paper reports the effects of fuel injection rate on the diesel combustion. Especially, the study focused on the inversed-delta injection rate.]]></description>
      <pubDate>Mon, 31 May 2021 20:18:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/1846392</guid>
    </item>
    <item>
      <title>Experimental study of pre-chamber jet ignition in a rapid compression machine and single-cylinder natural gas engine</title>
      <link>https://trid.trb.org/View/1777380</link>
      <description><![CDATA[Pre-chamber jet ignition is a promising combustion technology to achieve fast combustion in natural gas engines. First, the ignition and combustion characteristics of mixtures in a pre-chamber system with different diameter orifices were studied under engine-relevant pressures and temperatures in a rapid compression machine. The tested fuels, CH₄/air stoichiometric mixtures, were diluted by different proportions of CO₂/N₂ to simulate the corresponding exhaust gas recirculation conditions in engines. High-speed photography was applied to visualize the jet ignition and combustion processes. The experimental results revealed that two ignition patterns existed in the pre-chambers depending on the diameter of orifices. Pre-chamber jet flame ignition pattern appeared when the orifice diameter of the pre-chamber exceeded a critical value, which produced jet flame and ignited the mixtures in the main chamber directly. Pre-chamber jet auto-ignition pattern produced jet which promoted the auto-ignition of mixture in the main chamber when the orifice diameter was smaller and presented much shorter combustion durations. Based on the experimental results in the rapid compression machine, a practical pre-chamber system was designed in a single-cylinder natural gas engine to investigate the combustion performance and emission characteristics. The experimental results indicated appropriate 0.8%–1.4% increases of indicated thermal efficiency were achieved by pre-chamber jet ignition due to the higher combustion efficiency and shorter combustion duration compared to conventional spark ignition. Lower total hydrocarbon and CO emissions but higher NOₓ emissions were produced by pre-chamber jet ignition due to the faster burning velocity and higher combustion temperature.]]></description>
      <pubDate>Fri, 26 Mar 2021 17:44:54 GMT</pubDate>
      <guid>https://trid.trb.org/View/1777380</guid>
    </item>
    <item>
      <title>A Study on Reduction of In-Cylinder Heat Loss Using High-Speed IR Camera</title>
      <link>https://trid.trb.org/View/1770692</link>
      <description><![CDATA[In order to clarify the in-cylinder wall heat loss phenomena, visualization of flame behavior and wall surface temperature distribution was attempted in a top-view optical engine. Infrared radiation from chromium coated quartz window surface was visualized by high-speed infrared camera. Heat flux sensor measurement and CFD simulation were also conducted to compared with infrared radiation and to consider the effect of wall material difference between quartz and metal. Furthermore, appropriate sensor layout was investigated from distributions of infrared radiation taken by high-speed infrared camera. The obtained high-speed infrared images successfully demonstrated the potential of the visualization technique for qualitative measurement of wall surface temperature distribution, which will be beneficial for fundamental understanding, model development and its validation of the wall heat transfer process. As for the sensor layout consideration based on high-speed infrared images, it was found that wall heat loss within φ30mm can be obtained by radially dividing the measurement area into three and using nine sensors.]]></description>
      <pubDate>Mon, 22 Mar 2021 10:36:05 GMT</pubDate>
      <guid>https://trid.trb.org/View/1770692</guid>
    </item>
    <item>
      <title>Influences of multi spark discharge on lean ignition for premixed propane/air mixtures under turbulent environment</title>
      <link>https://trid.trb.org/View/1704559</link>
      <description><![CDATA[Spark ignition experiments were conducted to investigate effects of multi discharges on ignition of a lean-turbulence mixture. Initial flame kernel developments were observed by Schlieren photography, and discharge characteristics were analyzed by high-speed photography and spectroscopic measurements. Results indicated that the MIE (Minimum Ignition Energy) of the single discharge was lower than that of the multiple one at 100 kPa, and higher at 500 kPa. Each discharge was generated independently when discharge interval was set to 1 ms at 500 kPa, while discharge was occurred continuously at 100 kPa. This discharge characteristics might be related to the ignition performance.       ]]></description>
      <pubDate>Fri, 19 Jun 2020 14:19:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/1704559</guid>
    </item>
    <item>
      <title>Gasoline Fuel Sprays Characterization at Very-High Injection Pressures</title>
      <link>https://trid.trb.org/View/1704503</link>
      <description><![CDATA[In the modern GDI systems, the optimization of the fuel injection process is essential to prepare an air-fuel mixture capable to promote efficient combustion and reduce fuel consumption and pollutant emissions. A key feature for a better atomization is the fuel injection pressure. The increasing of the injection pressure is considered a good way for particle number (PN) reduction due to improved spray atomization, faster evaporation and better mixture formation.         In this paper, a multi-hole GDI injector was tested to investigate the effects of very high injection pressures (IVHP), in addition to different ambient densities and temperatures, on the fuel spray morphology, in a cycle-resolved images analysis. Commercial gasoline was injected at the pressures ranging between 40.0 to 70.0 MPa, at gas densities varying between 1.12 to 11.5 kg/m3, and gas temperature up to 200°C. Sequences of liquid and vapor images of the injected fuel were captured by Mie-scattering and shadowgraph optical techniques on a high-speed C-Mos camera and the characteristic parameters of the jets, tip penetrations, cone-angles, and fuel spread were extracted for both the phases by a customized image-processing procedure developed in C#. The effects of the single parameters affecting the spray evolutions, remaining constant the residual parameters, are reported and analyzed.       ]]></description>
      <pubDate>Thu, 18 Jun 2020 09:43:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/1704503</guid>
    </item>
    <item>
      <title>Impact of Multiple Injection Strategies on Efficiency and Combustion Characteristics in an Optical PPC Engine</title>
      <link>https://trid.trb.org/View/1702136</link>
      <description><![CDATA[Partially premixed combustion (PPC) is a promising way to achieve high thermal efficiency and low emissions, especially by using multiple injection strategies. The mechanisms behind PPC efficiency are still to be explained and explored. In this paper, multiple injections have been used to affect the gross indicated efficiency in an optical PPC engine modified from a Volvo MD13 heavy-duty diesel engine. The aim is both to improve and impair the gross indicated efficiency to understand the differences. The combustion natural luminosity is captured by a high-speed camera, and the distribution of fuel, oxygen, and temperature during the combustion process has been further explored by CFD simulation. The results show that with the right combination of the pilot, main, and post injection the gross indicated efficiency can be improved. Using a post injection in a triple-injection case show to have less effect on the combustion phasing than pilot injection in a double-injection case, while it can significantly affect combustion efficiency. The later of the double-injection cases tested (c30/16), has less heat transfer losses since the high-temperature region transported away from the cylinder head and piston bowl wall, which can be seen in the CFD-simulations. The highest gross indicated efficiency among the tested cases is given by the triple-injection case d38/24/6 as it reaches the best balance between the mixing and the local temperature through the jet-jet interactions and combustion-jet interactions.       ]]></description>
      <pubDate>Fri, 29 May 2020 09:46:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/1702136</guid>
    </item>
    <item>
      <title>Experimental Investigation of the Compression Ignition Process of High Reactivity Gasoline Fuels and E10 Certification Gasoline using a High-Pressure Direct Injection Gasoline Injector</title>
      <link>https://trid.trb.org/View/1701409</link>
      <description><![CDATA[Gasoline compression ignition (GCI) technology shows the potential to obtain high thermal efficiencies while maintaining low soot and NOx emissions in light-duty engine applications. Recent experimental studies and numerical simulations have indicated that high reactivity gasoline-like fuels can further enable the benefits of GCI combustion. However, there is limited empirical data in the literature studying the gasoline compression ignition process at relevant in-cylinder conditions, which are required for further optimizing combustion system designs. This study investigates the temporal and spatial evolution of the compression ignition process of various high reactivity gasoline fuels with research octane numbers (RON) of 71, 74 and 82, as well as a conventional RON 97 E10 gasoline fuel. A ten-hole prototype gasoline injector specifically designed for GCI applications capable of injection pressures up to 450 bar was used. Vapor and liquid penetration from high speed optical visualizations, as well as combustion measurement were studied in an optically accessible constant volume spray and combustion chamber. Near simultaneous shadowgraph and Mie scattering images were captured to investigate the spray characteristics. OH* chemiluminescence and natural luminosity images were recorded simultaneously to characterize the ignition process through two high-speed cameras. The experiments were conducted under a wide range of ambient charge gas conditions, including temperatures from 900 to 1200 Kelvin, charge gas pressures from 50 to 100 bar, oxygen levels from 10-21% to represent 0-50% exhaust gas recirculation (EGR) levels. The fuel was injected at 300 and 450 bar injection pressure. Results show that vapor penetration of the E10 and high reactivity gasoline fuels are similar, and the liquid penetration is related to the fuel density. With the OH* chemiluminescence images analysis, the ignition delay decreases, and the flame lift-off length moves upstream towards the injector tip with increasing ambient temperature, increasing charge gas pressure, increasing cetane number and decreasing EGR level. A gasoline ignition delay correlation and a lift-off length correlation considering the charge gas conditions and the fuel properties have been achieved.       ]]></description>
      <pubDate>Tue, 26 May 2020 10:42:17 GMT</pubDate>
      <guid>https://trid.trb.org/View/1701409</guid>
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