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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" />
    <description></description>
    <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>Impact of innovative boot-electronically controlled injector on the performance of marine low-speed engines</title>
      <link>https://trid.trb.org/View/2724600</link>
      <description><![CDATA[Injection rate shaping is one of the key measures to achieve energy saving and emission reduction in diesel engines. To apply this technology to marine low-speed engines, an innovative Boot-Electronically Controlled Injector (Boot-ECI) has been proposed. This new type of injector, featuring innovative injection rate shaping technology, effectively compensates for the shortcomings of traditional methods in terms of economic efficiency and operational stability, making it particularly suitable for application in marine low-speed engines. Based on the established models of the injector and a single-cylinder low-speed engine, this study thoroughly investigates the impact of switching delay time (tsd) and strat of injection (SOI) of the Boot-ECI on the indicated specific fuel consumption (ISFC) and NOₓ emissions of the engine. Through comparative analysis, the study reveals the differences in the roles of Boot-ECI and Traditional Electronically Controlled Injector (TECI) during the combustion process in engine and further discusses the specific impact of low lift of the Boot-ECI selection on engine performance. The results indicate that for Boot-ECI, employing a larger tsd offers a more pronounced advantage in reducing NOₓ concentration per unit increase in ISFC under low-load conditions compared to delaying SOI. When Boot-ECI performs a boot-shaped injection, there is an inflection point in the apparent heat release rate (AHRR) during the rise phase, which is associated with the transition from a low injection rate in state I to a high injection rate in state II during the boot-shaped injection. Compared to TECI, Boot-ECI demonstrates superior performance in managing the trade-off between NOₓ emissions and ISFC. Furthermore, as the needle low lift of the Boot-ECI increases, the contribution of SOI to NOₓ concentration reduction per unit increase in ISFC remains constant, while the contribution of tsd increases, especially at 25% load.]]></description>
      <pubDate>Wed, 23 Sep 2026 15:56:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/2724600</guid>
    </item>
    <item>
      <title>Influence of needle-geometry design on in-nozzle flow characteristics for fuel flexibility on marine engines</title>
      <link>https://trid.trb.org/View/2724599</link>
      <description><![CDATA[The design and positioning of the needle are crucial factors that determine the morphology and dynamics of the flow within the nozzle flow of modern fuel injectors. Their optimization is crucial for enhancing the quality of the air-fuel mixture and ensuring compliance with stringent international emission regulations for marine powertrains. This study compares three needle-tip geometries with a reference design utilized in marine injectors. Numerical simulations were employed to analyze the flow characteristics induced by these needle geometries at two needle-lift positions. These correspond to two operational modes typically employed to ensure fuel flexibility: low-lift for dual-fuel mode and high-lift for Diesel-only mode. A multiphase model coupled with thermodynamic closure derived via the Perturbed Chain Statistical Associating Fluid Theory (PC-SAFT) Equation of State (EoS) was utilized. In order to minimize the computational cost associated with this EoS, the thermodynamic and transport properties of the fuel were computed beforehand and saved in a structured table. The results demonstrated strong predictive capability with computational costs typically accepted for industrial design time scales. In low-lift positions, the flow was attached to the inner surfaces, due to the high velocity imposed by the narrow flow area of the needle seat. The base needle design exacerbates cavitation, but two of the proposed designs significantly reduce the cavitation intensity. This led to a significant decrease in the amount of fuel vapor forming inside the injector compared to the base design. Furthermore, one design relocates most of the cavitation area beyond the spray hole. At higher-lift positions, the designs can be categorized into two groups regarding the overall flow structure. The first one exhibits flow patterns similar to the base design and the second one exhibits reduced nozzle flow coefficients.]]></description>
      <pubDate>Wed, 23 Sep 2026 15:56:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/2724599</guid>
    </item>
    <item>
      <title>Structural sensitivity analysis and multi-objective optimization of liquid nozzle performances with the internal cavitation flow</title>
      <link>https://trid.trb.org/View/2724598</link>
      <description><![CDATA[The transient cavitation flow within the nozzle of a high-pressure micro-size injector is characterized by high turbulence and multi-phase. The inception and development of this flow are markedly affected by the nozzle geometries, which exert a direct influence on the injector nozzle reliability and the spray characteristics. This study presents a comprehensive evaluation of nozzle performance in terms of flow coefficient, spray patterns and cavitation erosion, with a particular focus on the sensitivity of the nozzle parameters using a combination of optical experiment, numerical simulation, and machine learning. According to the sensitivity analysis, the parameters of hole taper coefficient, needle lift and the combined needle lift and hole height have the most significant influence on the nozzle performances. Furthermore, a multi-objective optimization of the parameters of a nine-hole marine nozzle was conducted based on the Radial Basis Function neural network and the Non-dominated Sorting Genetic Algorithms-II genetic algorithm. Results present that the flow coefficient of the fitness-optimal nozzle shows an approximately 25% increase, while the near-nozzle liquid phase diffusion angle simultaneously demonstrates a marked increase exceeding 70%, and the cavitation erosion risk is sharply reduced.]]></description>
      <pubDate>Wed, 23 Sep 2026 15:56:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/2724598</guid>
    </item>
    <item>
      <title>Numerical simulation and optimization of injector and nozzle pattern of an opposed-piston two-stroke diesel engine</title>
      <link>https://trid.trb.org/View/2706079</link>
      <description><![CDATA[Opposed-Piston Two-Stroke (OP2S) diesel engine shows high-power density, low heat transfer loss and good balance performance. However, side-mounted injectors must be used because of their special architecture, which makes it necessary to redesign the injector. In this paper, the effects of injector nozzles arrangement, including the number of injectors, the number of nozzles and their installation position, on the mixing and combustion performance were studied by using CFD simulation. Results show that the distribution of the equivalence ratio was significantly influenced by the effects of in-cylinder swirl and injection pattern. This swirl-induced interaction among gaseous fuel, leading to their aggregation, subsequently affects the combustion rate. An adequate space among the injector nozzles is essential for improving air utilization and combustion process. Altering the injector mounting angle allowed for the exploitation of in-cylinder micro-tumble, which could enhance droplet breakup and subsequently improved the mixing and combustion processes, and the Indicated Mean Effective Pressure (IMEP) could be increased by 6.42% compared to the prototype engine, yet with fewer injectors.]]></description>
      <pubDate>Thu, 13 Aug 2026 17:07:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/2706079</guid>
    </item>
    <item>
      <title>Development of a Riemann variables-based technique for on-line fuel injected mass evaluation in direct injection systems</title>
      <link>https://trid.trb.org/View/2689376</link>
      <description><![CDATA[On-line evaluation of injected fuel mass based on physical principles offers the potential for accurate and rapid feedback on actual injection quantities. High-accuracy pressure transducers are commonly used as primary sensors to provide inputs for model-based virtual flowmeters. While increasing the number of transducers allows for a more comprehensive analysis of elementary waves within the system, balancing measurement accuracy and economic efficiency is essential for industrial applications. In this study, a physics-based technique requiring only a single pressure sensor on the injector-feeding pipe is proposed, considering two elementary waves. The algorithm employs a predefined signal that exploits quasi-constant Riemann variables propagating from the rail to the injector, enabling accurate estimation of the flow-rate and mass entering the injector. Correlation relationships are then used to convert the entering mass into the injected mass. This approach achieves an estimation accuracy within 2 mg for single injection events. The proposed method is benchmarked against a previously developed flowmeter utilizing two pressure sensors, demonstrating that comparable accuracy can be obtained with a more economical single-sensor setup. The algorithm is applicable across a wide range of injection sizes and working conditions, offering a practical solution for real-time injected mass evaluation and control in high-pressure fuel systems.]]></description>
      <pubDate>Fri, 31 Jul 2026 09:23:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/2689376</guid>
    </item>
    <item>
      <title>Effects of Retrofitting Diesel Engine Injector Nozzles, Focusing on Engine Performances</title>
      <link>https://trid.trb.org/View/2581428</link>
      <description><![CDATA[This experimental study investigates the impact of enlarging diesel injector nozzles on engine performance. The nozzle size was increased from 0.184 mm to 0.270 mm. Measurements conducted on a lab test bench under varied operating conditions reveal that larger nozzles enhance power output. This study provides new insights into the combustion dynamics with different nozzle dimensions, highlighting practical implications for optimizing diesel engine performance while meeting emissions regulations.]]></description>
      <pubDate>Mon, 13 Jul 2026 10:46:16 GMT</pubDate>
      <guid>https://trid.trb.org/View/2581428</guid>
    </item>
    <item>
      <title>Alcohol Diffusive Combustion Technique as an Alternative Diesel Combustion (Third Report)</title>
      <link>https://trid.trb.org/View/2684155</link>
      <description><![CDATA[In this study, we prototyped a dual-fuel high-pressure pump and a dual-fuel injector that controls two fuels using a single needle valve and injects them through the same nozzle orifice. In-cylinder observations revealed that a pilot injection with a high diesel fuel content ignites the main injection of an ethanol–diesel mixture, thereby achieving diffusive combustion. Experiments were conducted at engine speeds of 1000 and 2000 rpm under low-load conditions, with coolant temperatures of 80 °C and 40 °C. The optimum pilot injection timing and quantity were experimentally determined using a single-cylinder direct-injection diesel engine, with the objective of minimizing combustion noise, smoke, and CO emissions.]]></description>
      <pubDate>Tue, 23 Jun 2026 13:53:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2684155</guid>
    </item>
    <item>
      <title>Effects of injector configurations on RCCI mode of combustion in a light-duty diesel engine</title>
      <link>https://trid.trb.org/View/2679094</link>
      <description><![CDATA[Reactivity controlled compression ignition (RCCI) is a promising low temperature combustion technique that reduces nitrogen oxides (NOₓ) and soot emissions simultaneously in diesel engines. This experimental study examines the impact of injector configurations on combustion, performance and emissions of a light-duty diesel engine using compressed natural gas (CNG)-diesel RCCI combustion. Injectors with six, seven and eight holes were tested across low load using a single injection strategy and intermediate loads with a double-injections strategy at 1500 and 2800 rpm, with a start of injection (SOI) sweep. The work aims to address key fundamental questions such as (a) how injector configurations affect combustion phasing, engine-out emissions and associated trade-offs, (b) how single and double injection strategies influence above mentioned outcomes; and (c) whether the performance be further improved while preserving the inherent advantage of low NOₓ and soot emissions in the RCCI strategy. The six-hole injector showed higher peak heat release rates at low loads, while the eight-hole injector showed higher peak heat release rates at intermediate loads. The six-hole injector exhibited the shortest ignition delay and advanced combustion phasing, with a longer combustion duration compared to the seven-hole and eight-hole injectors. The eight-hole injector had higher combustion efficiency at low loads but underperformed at intermediate loads. Carbon monoxide and unburned hydrocarbons emissions were higher for the six-hole injector at low loads and for the eight-hole injector at intermediate loads. NOₓ and soot emissions were decreased with increase in injector hole numbers.]]></description>
      <pubDate>Thu, 11 Jun 2026 09:33:33 GMT</pubDate>
      <guid>https://trid.trb.org/View/2679094</guid>
    </item>
    <item>
      <title>Influence of alternative fuel from waste plastic oil on the macroscopic spray parameters utilising a single injection strategy in a piezoelectric diesel injector</title>
      <link>https://trid.trb.org/View/2663669</link>
      <description><![CDATA[An alternative way to utilise waste plastics is to use waste plastic oil (WPO) in diesel engines. One way to explore the potential of WPO as an alternative fuel in diesel engines is by determining the spray macroscopic parameters. The present research will study the spray macroscopic characteristics utilising WPO and ultra-low sulphur diesel (ULSD) as the fuel baseline. To do so, the spray macroscopic parameters will be characterised in a constant volume chamber under non-evaporative and non-reactive conditions and using injection pressures (pᵣₐᵢₗ) of 80, 100 and 120 MPa and a back pressure (pb) of 5 MPa. Among the main results reached, it can be highlighted that the spray tip penetration, spray cone angle, and spray area values of WPO are lower than those of ULSD in all injection pressure levels at the same time intervals after the start of injection. Moreover, analysing all macroscopic spray parameters and under the operating conditions studied, it can be concluded that the mixing process of WPO is faster than ULSD. Thus, WPO shows potential as an alternative fuel for diesel engines. Lastly, the present research provides useful information that may be used to support simulations of the injection process using WPO.]]></description>
      <pubDate>Tue, 28 Apr 2026 17:06:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/2663669</guid>
    </item>
    <item>
      <title>Numerical study of the atomization performance of coaxial and porous injectors in rocket engine applications</title>
      <link>https://trid.trb.org/View/2647094</link>
      <description><![CDATA[The numerical study involved in comparing the atomization performance of coaxial and porous injectors using the coupled volume of fluid and discrete phase CFD model (coupled VOF-DPM). The study focuses on the primary atomization region of the injection. The investigation is done to study the effect of water-air mass flow ratios on droplet parameters such as droplet size (SMD), axial and radial velocity, and the number of droplets at different injection times. Pore-level simulations are performed to study the performance of the porous injectors. It is observed that increasing the water-air mass flow ratio in both types of injectors leads to an increase in droplet size. The results showed that the droplet size produced by the coaxial injector is larger than that of the porous injector. Moreover, the number of droplets produced by the coaxial injector is lower than that produced by the porous injector. The smaller droplet size and larger number of droplets indicate better atomization in the porous injector.]]></description>
      <pubDate>Mon, 30 Mar 2026 08:56:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/2647094</guid>
    </item>
    <item>
      <title>Nonlinear characteristics of fuel injection quantity for a high-pressure common rail fuel injector</title>
      <link>https://trid.trb.org/View/2647131</link>
      <description><![CDATA[Based on a validated AMESim simulation model of the high-pressure common rail injector, the nonlinear characteristics of the fuel injection quantity were investigated in this article. The nonlinear relationship between the fuel injection quantity and the fuel injection pulse width was described quantitatively through the definition of the fuel injection quantity nonlinearity (FIQN). D-optimal experimental design and partial least squares regression were employed to construct response surface models for the FIQN under varying rail pressures. Then the analysis of variance (ANOVA) was conducted based on these predictive models to determine the significance of all factors by evaluating whether their p-values were less than 0.05. Additionally, correlation analysis was performed to reveal the degree and trend of influence each factor has on the FIQN. The results indicate that, under identical working conditions, single-factor effects are more significant on the FIQN compared to the interaction factors. The interactions of parameters themselves contribute little to the FIQN. While some parameter interactions do influence the nonlinear characteristics of the fuel injection quantity, the leading interaction factors vary across different rail pressures. Specifically, at 60 MPa rail pressure, the correlation coefficient of the interaction between the inlet orifice diameter and outlet orifice diameter is 0.50, which is the only interaction factor strongly related to the FIQN. When the inlet orifice diameter is at a high level and the outlet orifice diameter is at a low level, the nonlinear relationship between the fuel injection quantity and injection pulse width can be significantly improved.]]></description>
      <pubDate>Fri, 27 Mar 2026 10:14:18 GMT</pubDate>
      <guid>https://trid.trb.org/View/2647131</guid>
    </item>
    <item>
      <title>Multifactorial mechanisms of cavitation and spray atomization in diesel injector nozzles: A comprehensive review</title>
      <link>https://trid.trb.org/View/2647125</link>
      <description><![CDATA[Fueled by global environmental policies and energy transition initiatives, new energy vehicles are undergoing rapid development. However, internal combustion engines, particularly diesel-powered vehicles, continue to dominate the global automotive market. Owing to their high energy density and extended range, diesel engines are anticipated to remain critical, long-distance transportation, and industrial machinery for a long time to come. Therefore, optimizing diesel engine systems’ emission and combustion performance is crucial for enhancing energy efficiency and reducing global pollutant emissions. This review systematically examines the influence of nozzle geometry, operating conditions, and fuel properties on in-nozzle cavitation and near-field spray atomization in diesel injectors, culminating in proposed optimization strategies.]]></description>
      <pubDate>Tue, 27 Jan 2026 09:19:18 GMT</pubDate>
      <guid>https://trid.trb.org/View/2647125</guid>
    </item>
    <item>
      <title>Thermal effects on the cavitation flow characteristics in the control valve for the diesel injector</title>
      <link>https://trid.trb.org/View/2612388</link>
      <description><![CDATA[The control valve is a critical actuator component of the diesel injector, and the fuel flow characteristics within its millimeter-scale microchannels directly determine the dynamic response of the injector. The fuel within the control valve is highly prone to cavitation, accompanied by intense transient thermal effects, which in turn influence the cavitation flow. In this paper, to reveal the coupling mechanisms between thermal effects and cavitation in the control valve, the modified turbulence and cavitation model incorporating thermal effects were proposed, and a three-dimensional simulation study of the fuel flow characteristics was conducted. The results show that the fuel temperature inside the ball valve chamber increases significantly and unevenly, with the highest temperature rise of up to 115 K occurring near the surface of the ball valve chamber. The cavitation within the ball valve chamber also exhibits an uneven distribution, and it is influenced by the temperature rise distribution. Thermal effects influence cavitation in two ways. On the one hand, the temperature rise reduces fuel density, creating a large density gradient between the surface of the ball valve chamber and the central flow region. This gradient generates strong vorticity, increasing dynamic pressure and reducing static pressure, which promotes cavitation. On the other hand, the temperature rise raises the critical cavitation pressure, making cavitation more likely to occur. On the surfaces of the ball and the ball seat, the changes in temperature rise and cavitation are influenced by both position and pressure difference.]]></description>
      <pubDate>Mon, 29 Dec 2025 09:37:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/2612388</guid>
    </item>
    <item>
      <title>Establishment and calibration of performance simulation model for hydrogen injector of fuel cell</title>
      <link>https://trid.trb.org/View/2598286</link>
      <description><![CDATA[In order to meet the demand of the PEMFC digital prototype for high-precision simulation models of its key components, based on the analysis of the structure and working principle of the hydrogen injector, the mathematical model of the hydrogen injector was established according to the continuity equation and energy equation of gas flow. On this basis, the one-dimensional performance simulation model of the hydrogen injector was developed using Python computer language; a test bench for nozzle injection characteristics was setup. Compressed air was used to replace hydrogen. The nozzle injection characteristics were tested under different inlet and outlet pressures, and the test data of nozzle gas mass flow were obtained; through the test data and nozzle gas flow model, the orifice flow coefficient was determined to be 0.89, and the one-dimensional performance simulation model of hydrogen injector was calibrated; the accuracy of the one-dimensional performance simulation model of hydrogen injector is verified through various working conditions, and the accuracy of the simulation data can reach 97%, which lays a foundation for the development of the digital prototype of PEMFC.]]></description>
      <pubDate>Fri, 21 Nov 2025 08:46:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2598286</guid>
    </item>
    <item>
      <title>Thermal Efficiency Improvement for a High-compression-ratio HD Diesel Engine by Utilizing an Offset Orifice Nozzle</title>
      <link>https://trid.trb.org/View/2603808</link>
      <description><![CDATA[It has been necessary to investigate into combustion phenomena and fuel spray characteristics aiming to achieve thermal efficiency improved commercial heavy-duty diesel engines. This study focuses on the simultaneous improvement in cooling loss and indicated thermal efficiency by means of an offset orifice nozzle presented in the former study, and investigates further into combustion and emission characteristics of a high-compression-ratio heavy-duty diesel engine equipped with offset orifice nozzles. Internal nozzle flow analysis by numerical simulation and observation of fuel spray were also carried out to identify the cause of significantly different combustion phenomena.]]></description>
      <pubDate>Thu, 20 Nov 2025 17:07:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/2603808</guid>
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