Manipulating Tumble and Swirl Flows in Cylinder of a Motored Four-Valve Engine by Inlet Deflection Valve

AbstractEffects of the inlet-stream deflection on the temporal and spatial evolution processes of the in-cylinder flow structures (tumble/swirl) and turbulence intensities in the symmetry and diametral planes of a motored four-valve, four-stroke engine are diagnosed by using a particle image velocimeter. The inception, establishment, and evolution of the tumbling/swirling vortical flow structures during the intake and compression strokes in the engine cylinder with/without inlet-stream deflection are depicted and compared. Quantitative strengths of the rotating vortical flow motions are presented by dimensionless parameters (tumble and swirl ratios) which can represent the mean angular velocity of the vortices in the target plane. The turbulence intensity is calculated by using the measured time-varying velocity data. The results show that by deflecting the inlet air-stream the tumble and swirl ratios of the in-cylinder flow are appreciably increased by about 0.1 and the turbulence intensity is increased by about 5 ∼ 10%.

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Vortical Flow Structures Induced by Red Blood Cells in Capillaries

Microcirculation ◽

10.1111/micc.12693 ◽

2021 ◽

Author(s):

François Yaya ◽

Johannes Römer ◽

Achim Guckenberger ◽

Thomas John ◽

Stephan Gekle ◽

...

Keyword(s):

Red Blood Cells ◽

Blood Cells ◽

Vortical Flow ◽

Flow Structures

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Flow structures and particle deposition patterns in double-bifurcation airway models. Part 2. Aerosol transport and deposition

Journal of Fluid Mechanics ◽

10.1017/s0022112001003810 ◽

2001 ◽

Vol 435 ◽

pp. 55-80 ◽

Cited By ~ 79

Author(s):

J. K. COMER ◽

C. KLEINSTREUER ◽

C. S. KIM

Keyword(s):

Particle Deposition ◽

Air Flow ◽

Reynolds Numbers ◽

Companion Paper ◽

Stokes Number ◽

Vortical Flow ◽

Flow Structures ◽

Particle Distributions ◽

Deposition Patterns ◽

Inlet Conditions

The flow theory and air flow structures in symmetric double-bifurcation airway models assuming steady laminar, incompressible flow, unaffected by the presence of aerosols, has been described in a companion paper (Part 1). The validated computer simulation results showed highly vortical flow fields, especially around the second bifurcations, indicating potentially complex particle distributions and deposition patterns. In this paper (Part 2), assuming spherical non-interacting aerosols that stick to the wall when touching the surface, the history of depositing particles is described. Specifically, the finite-volume code CFX (AEA Technology) with user-enhanced FORTRAN programs were validated with experimental data of particle deposition efficiencies as a function of the Stokes number for planar single and double bifurcations. The resulting deposition patterns, particle distributions, trajectories and time evolution were analysed in the light of the air flow structures for relatively low (ReD1 = 500) and high (ReD1 = 2000) Reynolds numbers and representative Stokes numbers, i.e. StD1 = 0.04 and StD1 = 0.12. Particle deposition patterns and surface concentrations are largely a function of the local Stokes number, but they also depend on the fluid–particle inlet conditions as well as airway geometry factors. While particles introduced at low inlet Reynolds numbers (e.g. ReD1 = 500) follow the axial air flow, secondary and vortical flows become important at higher Reynolds numbers, causing the formation of particle-free zones near the tube centres and subsequently elevated particle concentrations near the walls. Sharp or mildly rounded carinal ridges have little effect on the deposition efficiencies but may influence local deposition patterns. In contrast, more drastic geometric changes to the basic double-bifurcation model, e.g. the 90°-non-planar configuration, alter both the aerosol wall distributions and surface concentrations considerably.

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Large Eddy Simulation of the Flow Around a Diffuser-Equipped Bluff Body in Ground Effect

Volume 6: Fluids and Thermal Systems; Advances for Process Industries, Parts A and B ◽

10.1115/imece2011-62673 ◽

2011 ◽

Cited By ~ 2

Author(s):

Lara Schembri Puglisevich ◽

Gary Page

Keyword(s):

Large Eddy Simulation ◽

Bluff Body ◽

Vortex Formation ◽

Ground Effect ◽

Vortical Flow ◽

Navier Stokes ◽

Flow Structures ◽

Eddy Simulation ◽

Large Eddy ◽

Flow Features

Unsteady Large Eddy Simulation (LES) is carried out for the flow around a bluff body equipped with an underbody rear diffuser in close proximity to the ground, representing an automotive diffuser. The goal is to demonstrate the ability of LES to model underbody vortical flow features at experimental Reynolds numbers (1.01 × 106 based on model height and incoming velocity). The scope of the time-dependent simulations is not to improve on Reynolds-Averaged Navier Stokes (RANS), but to give further insight into vortex formation and progression, allowing better understanding of the flow, hence allowing more control. Vortical flow structures in the diffuser region, along the sides and top surface of the bluff body are successfully modelled. Differences between instantaneous and time-averaged flow structures are presented and explained. Comparisons to pressure measurements from wind tunnel experiments on an identical bluff body model shows a good level of agreement.

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Experimental Analysis of the Impact of Injected Biofuels on In-Cylinder Flow Structures

SAE International Journal of Engines ◽

10.4271/2016-01-9043 ◽

2016 ◽

Vol 9 (2) ◽

pp. 1320-1348 ◽

Cited By ~ 2

Author(s):

Timo van Overbrueggen ◽

Marco Braun ◽

Michael Klaas ◽

Wolfgang Schroder

Keyword(s):

Experimental Analysis ◽

Flow Structures ◽

Cylinder Flow ◽

The Impact

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On the vortex dynamics of shear-driven deep cavity flows with asymmetrical walls

Canadian Journal of Physics ◽

10.1139/cjp-2016-0305 ◽

2016 ◽

Vol 94 (12) ◽

pp. 1344-1352 ◽

Cited By ~ 2

Author(s):

D. Cornu ◽

L. Keirsbulck ◽

F. Kerhervé ◽

F. Aloui ◽

M. Lippert

Keyword(s):

Physical Nature ◽

Wall Pressure ◽

Vortical Flow ◽

Flow Structures ◽

Cavity Flows ◽

Convective Structures ◽

Deep Cavity ◽

Image Velocimetry ◽

Flow Features ◽

Deep Cavities

The influence of the length-to-depth aspect ratio and of wall asymmetry on the main vortical flow structures evolving in rectangular two-dimensional deep cavities is studied experimentally using wall-pressure and particle image velocimetry (PIV) measurements. Wall-pressure and cavity flow statistics have been analyzed and shown that the flow features are strongly affected especially by the asymmetry. An emphasis is given concerning the behavior of the shear layer oscillations that are compared to the analytical deep-cavity model prediction proposed by P.J.W. Block (NASA Tech. Note. 1976). The results show good agreement with Block’s model if the value of the convection velocity is properly adjusted. Stochastic estimation of the cavity flows demonstrates that convective structures are involved downstream of the cavity along the wall and highlights the physical nature of the pressure-producing flow structures.

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Effects of Tumble and Swirl Flows on the Turbulence Scale Near the TDC in a 4-Valve S.I. Engine

Volume 2: In-Cylinder Processes: Fuel Spray, Flow, Ignition, Combustion, and Emission Formation ◽

10.1115/ices2001-119 ◽

2001 ◽

Cited By ~ 1

Author(s):

Ki Hyung Lee ◽

Chang Sik Lee ◽

Hyun Jong Park ◽

Dae Sik Kim

Keyword(s):

Flow Field ◽

Propagation Speed ◽

Turbulence Scale ◽

Iccd Camera ◽

Spark Plug ◽

Swirl Flows ◽

Intake Stroke ◽

Initial Flame ◽

Cylinder Flow ◽

Intake Flow

Abstract It has known that the in-cylinder flow field has a significant effect on the engine combustion. Especially, the turbulence scale at the ignition toning plays an important role in enhancing propagation speed of initial flame. Thus, in this study, various flow fields such as tumble and swirl flows were generated by intake flow control valves. The effects of tumble and swirl flows on the turbulence scale were experimentally investigated in a 4-valve S.I. engine. For the investigation of the flow field, the single frame PTV and the two color PIV techniques were developed to clarify in-cylinder flow pattern during intake stroke and turbulence intensity near the spark plug during compression stroke, respectively. The flame propagation was visualized by an ICCD camera and its images were analyzed to compare the flow field.

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