Internal and Near-Nozzle Flow in a Multi-Hole Gasoline Injector Under Flashing and Non-Flashing Conditions

Moulai, Maryam; Grover, Ronald O.; Parrish, Scott; Schmidt, David P.

doi:10.4271/2015-01-0944

Cited by 65 publications

(38 citation statements)

References 40 publications

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“…Alternatively, the diffuse interface approach attempts to model the behavior of the interface rather than resolve it. These types of models have been extremely successful in simulating diesel sprays [44,29,50,13,36,17,12], and recently they have been applied to GDI sprays by Moulai et al [23], Saha et al [35,34], and Strek et al [43]. These four works all similarly modeled GDI internal nozzle flow and near field flashing and non-flashing sprays through the spray G Engine Combustion Network (ECN) injector.…”

Section: Literature Review: Computationalmentioning

confidence: 99%

“…The use of these libraries provides a well-parallelized code with intrinsic polyhedral mesh support, as well as access to a wide variety of RANS and LES turbulence models and a multitude of pre and post processing utilities. The code has been well validated in many prior publications in applications ranging from channel flow [38], condensing two-phase injector flow [9], cavitating diesel flows [16], and flash-boiling GDI flow [23,43].…”

Section: Model Descriptionmentioning

confidence: 99%

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String flash-boiling in gasoline direct injection simulations with transient needle motion

Baldwin

Grover

Parrish

et al. 2016

International Journal of Multiphase Flow

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A computational study was performed to investigate the influence of transient needle motion on gasoline direct injection (GDI) internal nozzle flow and near-field sprays. Simulations were conducted with a compressible Eulerian flow solver modeling liquid, vapor, and non-condensable gas phases with a diffuse interface. Variable rate generation and condensation of fuel vapor were captured using the homogeneous relaxation model (HRM). The non-flashing (spray G) and flashing (spray G2) conditions specified by the Engine Combustion Network were modeled using the nominal spray G nozzle geometry. Transient needle lift and wobble were based upon ensemble averaged X-ray imaging preformed at Argonne National Lab. The minimum needle lift simulated was 5 µm and dynamic mesh motion was achieved with Laplacian smoothing. The results were qualitatively validated against experimental imaging and the experimental rate of injection profile was captured accurately using pressure boundary conditions and needle motion to actuate the injection. Low needle lift is shown to result in vapor generation near the injector seat. Finally, the internal injector flow is shown to be highly complex, containing many transient and interacting vortices which result in perturbations in the spray angle and fluctuations in the mass flux. This complex internal flow also results in intermittent string flash-boiling when a strong vortex is injected and the resulting swirling spray contains a thermal * Corresponding author

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Section: Literature Review: Computationalmentioning

confidence: 99%

Section: Model Descriptionmentioning

confidence: 99%

String flash-boiling in gasoline direct injection simulations with transient needle motion

Baldwin

Grover

Parrish

et al. 2016

International Journal of Multiphase Flow

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“…A range of models for injector internal and 45 near-nozzle flow continue to be developed, including volume-of-fluid methods [54,55], mixed-fluid models [56,57], and others. Recent simulations of Spray G suggest that complex transients in the vorticity of the sac flow play an important role in dictating the unsteadiness of the exit flow conditions and the mass balance between the plumes [58].…”

mentioning

confidence: 99%

Internal and near nozzle measurements of Engine Combustion Network “Spray G” gasoline direct injectors

Duke

Kastengren

Matusik

et al. 2017

Experimental Thermal and Fluid Science

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Gasoline direct injection (GDI) sprays are complex multiphase flows. When compared to multi-hole diesel sprays, the plumes are closely spaced, and the sprays are more likely to interact. The effects of multi-jet interaction on entrainment and spray targeting can be influenced by small variations in the mass fluxes from the holes, which in turn depend on transients in the needle movement and small-scale details of the internal geometry. In this paper, we present a comprehensive overview of a multi-institutional effort to experimentally characterize the internal geometry and near-nozzle flow of the Engine Combustion Network (ECN) Spray G gasoline injector. In order to develop a complete picture of the near-nozzle flow, a standardized setup was shared between facilities. A wide range of techniques were employed, including both x-ray and visible-light diagnostics. The novel aspects of this work include both new experimental measurements, and a comparison of the results across different techniques and facilities. The breadth and depth of the data reveal phenomena which were not apparent from analysis of the individual data sets. We show that plume-to-plume variations in the mass fluxes from the holes can cause large-scale asymmetries in the entrainment field and spray structure.Both internal flow transients and small-scale geometric features can have an effect on the external flow. The sharp turning angle of the flow into the holes also causes an inward vectoring of the plumes relative to the hole drill angle, which increases with time due to entrainment of gas into a low-pressure region between the plumes. These factors increase the likelihood of spray collapse with longer injection durations.

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“…There are several numerical studies on flash boiling for GDI injectors available in the literature [3,4,5,6,7]. Moulai et al [6] used the OpenFOAM ® CFD package to simulate the flash boiling condition by using a velocity boundary condition calculated from the rate of injection (ROI) data from experiments. Recently, Baldwin et al [7] used the OpenFOAM ® package to simulate the flash boiling under transient needle motion.…”

Section: Internal and Near Nozzle Flow Simulations Of Gasoline Multi-mentioning

confidence: 99%

Internal and Near Nozzle Flow Simulations of Gasoline Multi-Hole Injector (ECN Spray G) with Transient Needle Motion

Mohan¹,

Jaasim²,

Perez³

et al. 2018

Proceedings of the 10th International Symposium on Cavitation (CAV2018)

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In this work, the effect of transient needle motion on gasoline multi-hole injector's internal and near nozzle flow was studied. Spray G nozzle, an eight hole counter-bore injector from the Engine Combustion Network (ECN), was considered as the fluid domain. Simulations considered the effect of turbulence, cavitation, flash-boiling, compressibility and non-condensable gases under transient needle lift. To model the two phase flow inside and outside the nozzle, the Homogeneous Relaxation Model (HRM) coupled with the Volume of Fluid (VOF) approach was used. HRM model is used in this study because it uses an empirical timescale to reproduce a range of vaporizations mechanisms i.e. both cavitation and flash boiling mechanisms. To model turbulence, the RNG k − ε model was used. Simulations were performed with two different boundary conditions for the outlet domain to investigate non-flashing and evaporative (Spray-G) and flashing (Spray-G2) conditions. The simulation results were qualitatively validated against the experimental images and quantitatively against the experimental rate of injection (ROI) profile. The liquid plume angle showed good agreement with that of experimental measurement. The results show that the simulation is capable of capturing the ROI accurately with upstream pressure boundary condition and transient needle lift profile. Furthermore, the results show that the hole-to-hole variation in the total injected mass was not very significant. The simulation was also able to capture the cavitation phenomena inside the nozzles and flash boiling in the near nozzle region.

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Internal and Near-Nozzle Flow in a Multi-Hole Gasoline Injector Under Flashing and Non-Flashing Conditions

Cited by 65 publications

References 40 publications

String flash-boiling in gasoline direct injection simulations with transient needle motion

String flash-boiling in gasoline direct injection simulations with transient needle motion

Internal and near nozzle measurements of Engine Combustion Network “Spray G” gasoline direct injectors

Internal and Near Nozzle Flow Simulations of Gasoline Multi-Hole Injector (ECN Spray G) with Transient Needle Motion

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