Effect of viscosity, temperature and nozzle length-to-diameter ratio on internal flow and cavitation in a multi-hole injector

Nouri, J. M.; MacKenzie, Sophie; Gaskell, C.; Dhunput, Ashvin

doi:10.1533/9780857096043.7.265

Cited by 14 publications

(5 citation statements)

References 7 publications

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“…13,26 In a lubricant model investigation, 13 the increase in temperature resulted in decrease in oil film thicknesses, lubricant viscosities and advanced the initiation of the cavitation and enhanced its intensity. Similar results were obtained in a model multi-hole injector 26 using glycerol at different temperatures and showed that an increase in temperature had the effect of enhancing cavitation due to lower viscosity and weaker molecular bounding. So, the following images, Figure 13, show the difference in cavitation levels at different temperatures for the same lubricant (BP Castrol GTX 10w-40), at the same speed of 800 r/min and at the same CA.…”

Section: Resultsmentioning

confidence: 99%

“…It has been reported that cavitation is directly linked to the viscosity of lubricants/liquids and the viscosity is highly depended on the temperature. 13,26 In a lubricant model investigation, 13 the increase in temperature resulted in decrease in oil film thicknesses, lubricant viscosities and advanced the initiation of the cavitation and enhanced its intensity. Similar results were obtained in a model multi-hole injector 26 using glycerol at different temperatures and showed that an increase in temperature had the effect of enhancing cavitation due to lower viscosity and weaker molecular bounding.…”

Section: Resultsmentioning

confidence: 99%

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Cavitation between cylinder-liner and piston-ring in a new designed optical IC engine

Nouri

Vasilakos

Yan

2021

International Journal of Engine Research

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A new engine block with optical access has been designed and manufactured capable of running up to 3000 r/min with the same specification as the unmodified engine. The optical window allowed access to the full length of the liner over a width of 25 mm to investigate the lubricant flow and cavitation at contact point between the rings and cylinder-liner. In addition, it allowed good access into the combustion chamber to allow charged flow, spray and combustion visualisation and measurements using different optical methods. New custom engine management system with build in LabView allowed for the precise full control of the engine. The design of the new optical engine was a great success in producing high quality images of lubricant flow, cavitation formation and development at contact point at different engine speeds ranging from 208 to 3000 r/min and lubricant temperatures (30°C–70°C) using a high-speed camera. The results under motorised operation confirmed that there was no cavitation at contact points during the intake/exhaust strokes due to low in-cylinder presure, while during compression/expansion strokes, with high in-cylinder pressure, considerable cavities were observed, in particular, during the compression stroke. Lubricant temperatures had the effect of promoting cavities both in their intensity and covered ring area up to 50°C as expected. Beyond that, although the cavitation intensity increases further with temperature, its area reduces due to possible collapse of the cavitating bubbles at higher temperature. The change of engine speed from 208 to 800 r/min increased cavitating area considerably by 52% of the ring area and was further increased by 19% at 1000 r/min. After that, the results showed very small increase in cavitation area (1.3% at 2000 r/min) with similar intensity and distribution across the ring.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Cavitation between cylinder-liner and piston-ring in a new designed optical IC engine

Nouri

Vasilakos

Yan

2021

International Journal of Engine Research

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“…This agrees with the results of Saleh at al. [37], and Nouri et al in [38] where they also concluded that higher viscosity of fluid results in less formatted cavitation. At needle closing, cavitation vapor fraction dissipates (declines) later, so it was still visible on S6 and S7 at 1 ms after the injection starts, when the needle is almost closed.…”

Section: Influence Of Fuel Propertiesmentioning

confidence: 92%

Effect of the In-Cylinder Back Pressure on the Injection Process and Fuel Flow Characteristics in a Common-Rail Diesel Injector Using GTL Fuel

et al. 2021

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The presented paper aims to study the influence of mineral diesel fuel and synthetic Gas-To-Liquid fuel (GTL) on the injection process, fuel flow conditions, and cavitation formation in a modern common-rail injector. First, the influence on injection characteristics was studied experimentally using an injection system test bench, and numerically using the one-dimensional computational program. Afterward, the influence of fuel properties on internal fuel flow was studied numerically using a computational program. The flow inside the injector was considered as multiphase flow and was calculated through unsteady Computational Fluid Dynamics simulations using a Eulerian–Eulerian two-fluid approach. Finally, the influence of in-cylinder back pressure on the internal nozzle flow was studied at three distinctive back pressures. The obtained numerical results for injection characteristics show good agreement with the experimental ones. The results of 3D simulations indicate that differences in fuel properties influence internal fuel flow and cavitation inception. The location of cavitation formation is the same for both fuels. The cavitation formation is triggered regardless of fuel properties. The size of the cavitation area is influenced by fuel properties and also from in-cylinder back pressure. Higher values of back pressure induce smaller areas of cavitation and vice versa. Comparing the conditions at injection hole exit, diesel fuel proved slightly higher average mass flow rate and velocities, which can be attributed to differences in fluid densities and viscosities. Overall, the obtained results indicate that when considering the injection process and internal nozzle flow, GTL fuel can be used in common-rail injection systems with solenoid injectors.

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“…Suh and Lee 27 evaluated the impact of cavitation on diesel fuel atomization characteristics in enlarged nozzle replicas with various L/W ratios and calculated the droplet size, the velocity, and the counted fraction of detected droplets. Nouri et al 28 investigated the impacts of temperature, viscosity, and nozzle length-to-diameter ratio in two 3D six-hole transparent model injectors with complete optical access, which were 15 times bigger than the true size. The flow in a "two-stage" injector nozzle was studied in Ref.…”

Section: Introductionmentioning

confidence: 99%

Investigation of nozzle geometry and wall roughness effects on diesel injector flow

Zainab,

Syed

2023

AIP Advances

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The flow and design of fuel injector nozzles have a considerable influence on the spray and combustion characteristics of a diesel engine. In-cylinder combustion, atomization, and primary breakdown are all highly influenced by the cavitation and turbulence in the fuel injector nozzle. In this paper, the effect of the nozzle geometry parameters, wall roughness parameters, and pressure difference on the swirl number, mass flow rate, turbulent kinetic energy, and vapor volume fraction is explored. U-type nozzle hole geometry, a well-known benchmark for the injector nozzle flow, is used to evaluate mesh independence and model validation. Large-eddy simulations are performed to provide a precise presentation of the flow structures and turbulent eddies inside the nozzle. Multiphase flow is studied using the mixture model, whereas cavitation is studied using the Schnerr–Sauer model based on the Rayleigh–Plesset equation. We find that the wall roughness parameters have an exciting impact on the discharge coefficient, swirl number, and vapor volume fraction. Due to the non-monotonic dependence of nozzle flow characteristics on the pressure difference and the wall roughness parameters, we can always find such values of these input parameters that render optimal nozzle flow characteristics. In this way, these parameters provide good control of spray formation and consequently on the quality and rate of combustion in the diesel engine.

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Effect of viscosity, temperature and nozzle length-to-diameter ratio on internal flow and cavitation in a multi-hole injector

Cited by 14 publications

References 7 publications

Cavitation between cylinder-liner and piston-ring in a new designed optical IC engine

Cavitation between cylinder-liner and piston-ring in a new designed optical IC engine

Effect of the In-Cylinder Back Pressure on the Injection Process and Fuel Flow Characteristics in a Common-Rail Diesel Injector Using GTL Fuel

Investigation of nozzle geometry and wall roughness effects on diesel injector flow

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