Nozzle Flow Simulation of GDi for Measuring Near-Field Spray Angle and Plume Direction

2019 ◽  
Author(s):  
Raul Payri ◽  
Jaime Gimeno ◽  
Pedro Marti-Aldaravi ◽  
María Martínez
Keyword(s):  
Near Field ◽  
Flow Simulation ◽  
Spray Angle ◽  
Nozzle Flow

WAVELET-BASED POSTPROCESSING OF JET LES DATA FOR ACOUSTIC FAR-FIELD EXTRAPOLATIONS

2013 ◽  
Vol 21 (04) ◽  
pp. 1350017
Author(s):  
RAMIN KAVIANI ◽  
VAHID ESFAHANIAN ◽  
MOHAMMAD EBRAHIMI
Keyword(s):  
Large Scale ◽  
Stokes Equations ◽  
Near Field ◽  
Flow Simulation ◽  
Computational Time ◽  
Jet Flows ◽  
Small Scale ◽  
Frequency Noise ◽  
Far Field ◽  
Noise Sources

The affordable grid resolutions in conventional large-eddy simulations (LESs) of high Reynolds jet flows are unable to capture the sound generated by fluid motions near and beyond the grid cut-off scale. As a result, the frequency spectrum of the extrapolated sound field is artificially truncated at high frequencies. In this paper, a new method is proposed to account for the high frequency noise sources beyond the resolution of a compressible flow simulation. The large-scale turbulent structures as dominant radiators of sound are captured in LES, satisfying filtered Navier–Stokes equations, while for small-scale turbulence, a Kolmogorov's turbulence spectrum is imposed. The latter is performed via a wavelet-based extrapolation to add randomly generated small-scale noise sources to the LES near-field data. Further, the vorticity and instability waves are filtered out via a passive wavelet-based masking and the whole spectrum of filtered data are captured on a Ffowcs-Williams/Hawkings (FW-H) surface surrounding the near-field region and are projected to acoustic far-field. The algorithm can be implemented as a separate postprocessing stage and it is observed that the computational time is considerably reduced utilizing a hybrid of many-core and multi-core framework, i.e. MPI-CUDA programming. The comparison of the results obtained from this procedure and those from experiments for high subsonic and transonic jets, shows that the far-field noise spectrum agree well up to 2 times of the grid cut-off frequency.

Coupled in-nozzle flow and spray simulation of Engine Combustion Network Spray-G injector

2020 ◽  
pp. 146808742096061
Author(s):  
Balaji Mohan ◽  
Jihad Badra ◽  
Jaeheon Sim ◽  
Hong G Im
Keyword(s):  
Cone Angle ◽  
Flow Simulation ◽  
Published Data ◽  
Nozzle Flow ◽  
Piv Measurements ◽  
Injection Model ◽  
Image Velocimetry ◽  
Spray Plume ◽  
Engine Combustion ◽  
Phase Change Phenomena

A coupled Eulerian-Lagrangian approach was employed to Engine Combustion Network (ECN) Spray-G simulations. The Eulerian in-nozzle flow simulation was conducted with a small plenum attached to the nozzles, and the results were fed to the Lagrangian spray simulation. For Eulerian simulation, the homogeneous relaxation model (HRM) coupled with the volume of fluid (VOF) method was used. HRM proved to be good at predicting the phase change phenomena due to vaporization mechanisms, that is, both cavitation and flash boiling. As a one-way coupling, quantities such as rate of injection (ROI), mass injected through each hole, discharge coefficient, spray plume angle and half cone angle predicted from the Eulerian simulations were used as the initial and boundary conditions for the subsequent Lagrangian spray simulations using the blob injection model. Non-flashing (Spray-G1) and flashing (Spray-G2) spray was simulated, and the results were validated quantitatively against the published data in terms of the liquid and vapor penetration lengths, and good agreements were obtained. Furthermore, the simulation predicted the liquid and gas axial velocity and sauter mean diameter for Spray-G1 condition in agreement with the droplet size and particle image velocimetry (PIV) measurements from literature.

GDi Skew-Angled Nozzle Flow and Near-Field Spray Analysis using Optical and X-Ray Imaging and VOF-LES Computational Fluid Dynamics

2013 ◽  
Author(s):  
Bizhan Befrui ◽  
Andreas Aye ◽  
Peter Spiekermann ◽  
Daniel L. Varble ◽  
Mark A. Shost ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Near Field ◽  
Nozzle Flow ◽  
X Ray ◽  
X Ray Imaging

Effect of Ambient Pressure on the Behavior of Single-Component Fuels in a Gasoline Multi-Hole Injector

2019 ◽  
Author(s):  
Lorenzo Nocivelli ◽  
Junhao Yan ◽  
Kaushik Saha ◽  
Gina M. Magnotti ◽  
Chia-Fon Lee ◽  
...  
Keyword(s):  
Ambient Pressure ◽  
Light Attenuation ◽  
Flow Simulation ◽  
Nozzle Flow ◽  
Numerical Representation ◽  
Air Mixing ◽  
Nominal Condition ◽  
Flash Boiling ◽  
Characteristic Features ◽  
Attenuation Profiles

Abstract The injection characteristics of neat ethanol and pure iso-octane are studied under different ambient pressure and temperature conditions. Injection under flash-boiling conditions can enhance liquid atomization and evaporation, providing the possibility of improvement in the fuel/air mixing. These super-heated conditions often introduce phenomena that are not taken into account in the standard modeling of sprays for engine applications. The present work proposes a numerical investigation of the behavior of Engine Combustion Network’s 8-hole spray-G injector, starting at the subcooled nominal condition and reducing the ambient pressure at constant low temperature to reach the flare flash-boiling condition. To initialize the properties of the injected fuel, the flow in the nozzle is simulated with a Eulerian approach, handling the two phases with a mixture model and the phase change, due to cavitation and flash boiling, with the Homogenous Relaxation Model. A map of the mixture’s kinematic and thermal behavior is obtained at the interface between the injector and the chamber to initialize the Lagrangian simulations. A literature-based vaporization model is implemented to obtain the proper description of the characteristic features of a multi-hole spray under super-heated conditions, like plume-plume interaction. The numerical representation of the spray is validated in terms of penetration and radial spreading on DBI images, reproducing the light attenuation profiles caused by the presence of the liquid spray. Simulations show that coupled nozzle flow and spray calculations capture the spray morphology and shape better compared to calculations performed without considering the nozzle flow simulation details, especially under flare flash conditions.

High-temperature effect of a gas jet of reacting components on an inclined plate

2021 ◽  
Author(s):  
I.S. Partola ◽  
A.S. Kudinov ◽  
I.I. Yurchenko ◽  
A.G. Klimenko ◽  
S.A. Fedorov
Keyword(s):  
High Temperature ◽  
Near Field ◽  
Pressure Ratio ◽  
Flow Simulation ◽  
Normal Pressure ◽  
Heat Fluxes ◽  
Inclined Plate ◽  
Reacting Mixtures ◽  
Good Agreement ◽  
High Temperature Effect

The purpose of the research was to experimentally and computationally study the distribution of pressures and heat fluxes when near-design jets of high-temperature reacting mixtures on the oxygen-kerosene, oxygen-methane, oxygen-ethanol components act on an inclined plate in the near field of the jet within the distance equal to nozzle exit diameter for pressure ratio The paper introduces the results of these studies. They were carried out with jets flowing with total temperatures of into ambient environment with normal pressure and temperature. The level of heat fluxes created by the jet on the plate was in range within Calculations in the SolidWorks Flow Simulation environment for the effect of a high-temperature flow for a perfect gas with parameters corresponding to the chemical composition in a model combustion chamber showed good agreement with experimental data.

Experimental and Numerical Investigation of Near-Nozzle Flow Behaviour Under Flash Boiling Conditions

2017 ◽  
Author(s):  
Bo Wang ◽  
Xinyu Zhang ◽  
Yuying Yan ◽  
Jean-Paul Kone
Keyword(s):  
High Speed ◽  
Flow Behavior ◽  
Near Field ◽  
Air Entrainment ◽  
Nozzle Flow ◽  
Ambient Conditions ◽  
Fuel Temperature ◽  
Long Distance ◽  
Significant Difference ◽  
Flash Boiling

Precise control of the spray behavior is key to fully realize the potential benefits of modern GDI engines. Flash boiling is known to alert the spray behavior significantly; and thus, a complete understanding of its mechanism is essential. In this work, a study of the effect of the fuel properties on the near-nozzle flow characteristics of a single-hole GDI injector under the flash boiling conditions is presented. The performance of hexane and a typical gasoline surrogate iso-octane has been studied both experimentally and numerically. Fuel temperature varied from 20 and 100 °C with ambient pressures of 20, 50 and 100 kPa. For the experiment, microscopic imaging was conducted with a high-speed camera coupled with a long-distance microscope; and a convex lens was used to provide enough illumination to the interested area. The numerical studies were performed at the maximum needle lift using OpenFOAM, an open-source Computational Fluid Dynamics (CFD) code. Phase change was captured with the Homogeneous Relaxation Model (HRM); and turbulence was modeled using RNG k–ε model. The results have shown that while the near-field flow behavior of hexane and isooctane was similar under ambient conditions, a significant difference was observed between the two under the flash boiling conditions. The onset and development of flash boiling of isooctane was retarded compared to hexane due to its much lower vapor pressure. Spray contraction has been observed in the down-stream due to fuel vaporization and air entrainment. The CFD results were shown to agree well with the experimental data.

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