scholarly journals Using PIV Measurements to Determine the Role of the In-Cylinder Flow Field for Stratified DISI Engine Combustion

2014 ◽  
Vol 7 (2) ◽  
pp. 615-632 ◽  
Author(s):  
Wei Zeng ◽  
Magnus Sjöberg ◽  
David Reuss
Keyword(s):  
Flow Field ◽  
Piv Measurements ◽  
Engine Combustion ◽  
Cylinder Flow

Systematic Multi-Index Validations of SIDI Engine Flow Field LES Computations Using Crank Angle-Resolved PIV Measurements

2019 ◽  
Author(s):  
Mengqi Liu ◽  
Fengnian Zhao ◽  
Xuesong Li ◽  
Min Xu ◽  
Zongyu Yue ◽  
...  
Keyword(s):  
Flow Field ◽  
Flow Fields ◽  
Model Verification ◽  
Piv Measurements ◽  
Multi Index ◽  
Global Indices ◽  
Comparison Results ◽  
Crank Angle ◽  
Flow Field Characteristics ◽  
Cylinder Flow

Abstract In-cylinder flow fields make significant impacts on the fuel atomization, fuel mixture formation, and combustion process in spark ignition direct injection (SIDI) engines. In recent years, model-based simulation approaches are preferred in regard to investigating the transient in-cylinder flow field characteristics. Most commonly, the simulation models are validated using single representative flow field at a typical crank angle measured by particle image velocimetry (PIV). However, it provides only limited knowledge about the flow field which is highly three-dimensional and of transient nature. In this study, crank angle-resolved PIV measurements are conducted on three distinct planes inside the cylinder to capture the transient process of flow field characteristics which vary with the crank angle. These three planes consist of one tumble plane through the spark plug tip, one tumble plane along two intake ports, and one swirl plane at 30 mm below the cylinder head. Large eddy simulation (LES) is employed for the numerical computations using the CONVERGE codes. On the basis of large datasets for both temporal and spatial domains, a multi-index systematic validation approach is conducted. Crank angle-resolved calculations of global indices and local indices are implemented using the flow fields velocity data obtained from both PIV and LES on select planes. Global indices reveal the trends in similarities of different crank angle degrees and locations, while local indices give the detail comparison results. In summary, with the systematic multi-index validation approach, the crucial crank angle degrees and locations for model verification will be detected. Furthermore, the corresponding critical flow features are analyzed. Practical guideline of flow field validation is proposed.

scholarly journals Hydrodynamics can determine the optimal route for microswimmer navigation

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Abdallah Daddi-Moussa-Ider ◽  
Hartmut Löwen ◽  
Benno Liebchen
Keyword(s):  
Flow Field ◽  
Hydrodynamic Interactions ◽  
Optimal Trajectories ◽  
Optimal Route ◽  
Active Particles ◽  
Navigation Strategy ◽  
Navigation Strategies

AbstractAs compared to the well explored problem of how to steer a macroscopic agent, like an airplane or a moon lander, to optimally reach a target, optimal navigation strategies for microswimmers experiencing hydrodynamic interactions with walls and obstacles are far-less understood. Here, we systematically explore this problem and show that the characteristic microswimmer-flow-field crucially influences the navigation strategy required to reach a target in the fastest way. The resulting optimal trajectories can have remarkable and non-intuitive shapes, which qualitatively differ from those of dry active particles or motile macroagents. Our results provide insights into the role of hydrodynamics and fluctuations on optimal navigation at the microscale, and suggest that microorganisms might have survival advantages when strategically controlling their distance to remote walls.

Experimental and Numerical Investigations of a Turbulent Flow Behavior in Isolated and Nonisolated Conical Diffusers

2011 ◽  
Vol 133 (1) ◽  
Author(s):  
F. Aloui ◽  
E. Berrich ◽  
D. Pierrat
Keyword(s):  
Turbulent Flow ◽  
Flow Behavior ◽  
Piv Measurements ◽  
Numerical Investigations ◽  
Image Velocimetry ◽  
Sst Model ◽  
Proper Orthogonal ◽  
Hydraulic Circuits

In some industrial processes, and especially in agrofood industries, the cleaning in place mechanism used for hydraulic circuits plays an important role. This process needs a good knowledge of the hydrodynamic flows to determinate the appropriate parameters that assure a good cleaning of these circuits without disassembling them. Generally, different arrangements are present in these hydraulic circuits, such as expansions, diffusers, and elbows. The flow crossing these singularities strongly affects the process of cleaning in place. This work is then a contribution to complete recent studies of “aliments quality security” project to ameliorate the quality of the cleaning in place. It presents experimental and numerical investigations of a confined turbulent flow behavior across a conical diffuser (2α=16 deg). The role of a perturbation caused by the presence of an elbow in the test section, upstream of the progressive enlargement, was studied. The main measurements were the static pressure and the instantaneous velocity fields using the particle image velocimetry (PIV). Post-processing of these PIV measurements were adopted using the Γ2 criterion for the vortices detection and the proper orthogonal decomposition (POD) technique to extract the most energetic modes contained in the turbulent flow and to the turbulent flow filtering. A database has been also constituted and was used to test the validity of the most models of turbulence, and in particular, a variant of the shear stress transport (SST) model.

Numerical Analysis of Swirl Control Strategies in a Four Valve HSDI Diesel Engine

2004 ◽  
Author(s):  
S. Fontanesi ◽  
E. Mattarelli ◽  
L. Montorsi
Keyword(s):  
Flow Field ◽  
Control Strategies ◽  
Cfd Simulations ◽  
Full Load ◽  
Partial Load ◽  
Swirl Intensity ◽  
Port Design ◽  
Current Production ◽  
Hsdi Diesel Engine ◽  
Cylinder Flow

Recent four value HSDI Diesel engines are able to control the swirl intensity, in order to enhance the in-cylinder flow field at partial load without decreasing breathing capabilities at full load. Making reference to a current production engine, the purpose of this paper is to envestiage the influence of port design and flow-control strategies on both engine permeability and in-cylinder flow field. Using previously validated models, 3-D CFD simulations of the intake and compression strokes are performed in order to predict the in-cylinder flow patterns originated by the different configurations. The comparison between the two configurations in terms of airflow at full load indicates that Geometry 2 can trap 3.03% more air than Geometry 1, while the swirl intensity at IVC is reduced (−30%). The closure of one intake valve (the left one) is very effective to enhance the swirl intensity at partial load: the Swirl Ratio at IVC passes from 0.7 to 2.6 for Geometry 1, while for Geometry 2 it varies from 0.4 to 2.9.

Flow Measurements in a Nozzle Guide Vane Passage With a Low Aspect Ratio and Endwall Contouring

2000 ◽  
Author(s):  
Steven W. Burd ◽  
Terrence W. Simon
Keyword(s):  
Aspect Ratio ◽  
Flow Field ◽  
Guide Vane ◽  
Flow Measurements ◽  
Vast Number ◽  
Aspect Ratios ◽  
Nozzle Guide Vane ◽  
Endwall Contouring ◽  
Nozzle Guide

The vast number of turbine cascade studies in the literature has been performed in straight-endwall, high-aspect-ratio, linear cascades. As a result, there has been little appreciation for the role of, and added complexity imposed by, reduced aspect ratios. There also has been little documentation of endwall profiling at these reduced spans. To examine the role of these factors on cascade hydrodynamics, a large-scale nozzle guide vane simulator was constructed at the Heat Transfer Laboratory of the University of Minnesota. This cascade is comprised of three airfoils between one contoured and one flat endwall. The geometries of the airfoils and endwalls, as well as the experimental conditions in the simulator, are representative of those in commercial operation. Measurements with hot-wire anemometry were taken to characterize the flow approaching the cascade. These measurements show that the flow field in this cascade is highly elliptic and influenced by pressure gradients that are established within the cascade. Exit flow field measurements with triple-sensor anemometry and pressure measurements within the cascade indicate that the acceleration imposed by endwall contouring and airfoil turning is able to suppress the size and strength of key secondary flow features. In addition, the flow field near the contoured endwall differs significantly from that adjacent to the straight endwall.

Time-resolved PIV measurements of the flow field in a stenosed, compliant arterial model

2013 ◽  
Vol 54 (5) ◽  
Author(s):  
P. H. Geoghegan ◽  
N. A. Buchmann ◽  
J. Soria ◽  
M. C. Jermy
Keyword(s):  
Flow Field ◽  
Time Resolved ◽  
Piv Measurements ◽  
Arterial Model

PIV Measurements of Propeller Flow Field in a Large Cavitation Tunnel

2011 ◽  
Author(s):  
Takayuki Mori ◽  
Risa Kimoto ◽  
Kenji Naganuma
Keyword(s):  
Flow Field ◽  
Velocity Profiles ◽  
Marine Propeller ◽  
Measured Velocity ◽  
Piv Measurements ◽  
Tip Vortices ◽  
Systems Research ◽  
Tracer Particles ◽  
Cavitation Tunnel ◽  
Blade Tip

Flow field around a marine propeller was measured by means of PIV technique in a large cavitation tunnel of the Naval Systems Research Center, TRDI/Ministry of Defense, Japan. Test section of the tunnel is 2m(W) × 2m(H) × 10m(L) and it contains 2000m3 of water. 2-dimensional PIV (2-D PIV) and stereo PIV (SPIV) measurements were made for a five-bladed highly skewed marine propeller. In the case of 2-D PIV measurements, high spatial resolution measurements were possible by seeding relatively small amount of tracer particles. Phase-averaged flow fields showed details on evolution of tip vortices. In the case of SPIV measurements, much larger amounts of tracer particles were required, and it was difficult to perform high resolution measurements. Phase averaged velocity profiles from SPIV measurements showed good agreement with 2-D PIV-measured results. PIV-measured results were compared with results of LDV measurements. Although PIV-measured velocity profiles showed fairly good agreements with LDV-measured results, some discrepancies were found at the blade tip region.

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