Squish and Swirl-Squish Interaction in Motored Model Engines

1983 ◽  
Vol 105 (1) ◽  
pp. 105-112 ◽  
Author(s):  
C. Arcoumanis ◽  
A. F. Bicen ◽  
J. H. Whitelaw
Keyword(s):  
Laser Doppler Anemometry ◽  
Axial Flow ◽  
Turbulent Energy ◽  
Toroidal Vortex ◽  
Complex Flow ◽  
Ic Engine ◽  
Solid Body Rotation ◽  
Piston Bowl ◽  
Flow Configurations ◽  
Turbulence Generation

Measurements of the three components of velocity and their corresponding fluctuations have been obtained by laser-Doppler anemometry mainly near TDC of compression in a model IC engine motored at 200 rpm with compression ratio of 6.7. The flow configurations comprised an axisymmetric cylinder head with and without upstream induced swirl and each of a flat piston and two centrally located, cylindrical and re-entrant, bowl-in-piston arrangements. In the absence of swirl and squish, the intake-generated mean motion and turbulence decayed considerably by the end of compression. The two piston-bowl configurations, however, resulted in a compression-induced squish motion with consequent formation of a toroidal vortex occupying the whole bowl space. Interacton of swirl, carried from intake and persisting through compression, with squish generated near TDC profoundly altered the axial flow structure. In the case of the cylindrical bowl, the sense of the vortex was reversed by swirl and, in the reentrant bowl, increased the number of vortices to two. The swirling motion inside the cylindrical bowl was close to solid body rotation while the re-entrant bowl gave rise to more complex flow patterns. Squish, in the presence or absence of swirl, did not augment the turbulent energy inside the cylindrical bowl contrary to the reentrant configuration where turbulence generation was observed.

Effects of Flow and Geometry Boundary Conditions on Fluid Motion in a Motored IC Model Engine

1982 ◽  
Vol 196 (1) ◽  
pp. 1-10 ◽  
Author(s):  
C Arcoumanis ◽  
A F Bicen ◽  
N S Vlachos ◽  
J H Whitelaw
Keyword(s):  
Boundary Conditions ◽  
Cylinder Head ◽  
Laser Doppler Anemometry ◽  
Fluid Motion ◽  
Axisymmetric Flow ◽  
Ic Engine ◽  
Piston Cylinder ◽  
Wide Range ◽  
Inlet Geometry ◽  
Flow Configurations

Measurements of ensemble-averaged axial velocities and the r.m.s. of the corresponding fluctuations, obtained by laser-Doppler anemometry, are reported for axisymmetric flow in a non-compressing piston-cylinder assembly motored at 200 rev/min simulating an IC engine. The inlet geometry comprised an open valve, located centrally and flush with the cylinder head, with seat angles of 30° and 60° and incorporating 30° swirl vanes. Results are presented for bore-to-stroke ratios of 0.83 and 1.25 and swept-to-clearance volume ratios of 2,3 and 9. The results indicate strong similarities between the flow structures for different stroke and clearance; a system of vortices is formed with a large vortex occupying most of the flow space and with smaller vortices in the corners between the wall, piston and cylinder head. The influence of valve seat angle is more pronounced and results, for the 30° angle, in adherence of the incoming jet to the cylinder head with increase of the overall turbulence levels and creation of stronger and longer living vortices. Previous results obtained in related compressing and non-compressing flow configurations are reviewed and, together with the present results, enable the influence of a wide range of possible geometric and flow boundary conditions to be quantified.

Intake Valve and In-Cylinder Flow Development in a Reciprocating Model Engine

1986 ◽  
Vol 200 (2) ◽  
pp. 143-152 ◽  
Author(s):  
C Vafidis ◽  
J H Whitelaw
Keyword(s):  
Flow Field ◽  
Laser Doppler Anemometry ◽  
Axial Flow ◽  
Normal Stresses ◽  
Intake Valve ◽  
Inlet Valve ◽  
Piston Bowl ◽  
Flow Development ◽  
Model Engine ◽  
Cylinder Flow

Measurements of three velocity components have been obtained by laser Doppler anemometry at the exit plane of the intake valve and inside the cylinder of a model engine motored at 200 r/min with a compression ratio of 7.7 and both axisymmetric and off-centre valves with flat and bowl-in-piston configurations. The results indicate that during early intake the valve flow is influenced by piston geometry and its proximity to the cylinder head. With the flat piston the TDC flow field is influenced by the intake-generated axial flow pattern but not by the tangential motion, induced by the off-centre valve, which decays around inlet valve closure. The breakdown of the intake-generated vortices is accompanied by redistribution of the normal stresses which, during compression, tend towards homogeneity. Inside the piston bowl, a vortex is induced during early intake and decays later in the induction stroke to a uniform flow field which is transformed during late compression by the squish effect.

Intake Turbulence Generated by a Steady Valve-Cylinder Flow

2002 ◽  
Author(s):  
Gearle Bailey ◽  
John Kuhlman
Keyword(s):  
Laser Doppler Anemometry ◽  
Axisymmetric Flow ◽  
Valve Lift ◽  
Intake Port ◽  
Intake Valve ◽  
Toroidal Vortex ◽  
Velocity Measurements ◽  
Mean Velocity ◽  
Cylinder Flow ◽  
Turbulence Generation

Axial and swirl velocities have been measured for steady axisymmetric flow in a cylinder past a fixed intake valve located on the cylinder centerline, for two different intake port geometries and two valve lifts, in order to study the effects of swirl and valve lift on turbulence generation. Both Laser Doppler Anemometry (LDA) and Constant Temperature Anemometry (CTA) velocity measurements were obtained. The cylinder diameter was 82.6 mm, cylinder height was 114.3 mm, and the centrally located valve had a diameter of 41.9 mm. The LDA mean axial velocity data indicated a conical jet issuing from the valve, and a recirculating toroidal vortex above the valve for each case. Also, for the swirl intake cases, the swirl mean velocity in the toroidal vortex increased linearly with radius. Axial fluctuation velocities were about 1 m/sec away from the conical jet, for both valve lifts and both inlet flow geometries. In the conical jet, axial fluctuation velocities of 2–2.5 m/sec were observed. The swirl fluctuation was consistently lower than the axial fluctuation. The swirl inlet increased the magnitude of the swirl fluctuation in the conical jet.

Numerical Prediction of Fluid Flow and Diesel Combustion in a Pre-Chamber and Main Chamber

2005 ◽  
Author(s):  
Bassem H. Ramadan ◽  
Prashant Ahire
Keyword(s):  
Fluid Flow ◽  
Diesel Combustion ◽  
Cylinder Pressure ◽  
Main Chamber ◽  
Ic Engine ◽  
Piston Bowl ◽  
Air Mixing ◽  
Model Fluid ◽  
Computational Fluid Dynamics Cfd ◽  
Turbulence Generation

In this study computational fluid dynamics (CFD) was used to model fluid flow and diesel combustion in an IC engine that uses a pre-chamber and a main-chamber. The pre-chamber is located in the cylinder head and a bowl in the piston serves as the main chamber. The study considers the effect of diesel combustion in the pre-chamber on turbulence generation and hence fuel-air mixing and combustion in the piston-bowl. Diesel fuel was injected directly into the pre-chamber and the piston bowl at different times. In order to better determine the effect of pre-chamber combustion on the main chamber combustion, various pre-chamber injection timings were considered. The results show that pre-chamber combustion caused the average cylinder pressure to increase by up to 20% in some cases.

scholarly journals Study of Pumping Capacity of Pitched Blade Impellers

10.14311/380 ◽  
2002 ◽  
Vol 42 (4) ◽  
Author(s):  
I. Fořt ◽  
T. Jirout ◽  
R. Sperling ◽  
S. Jambere ◽  
F. Rieger
Keyword(s):  
Laser Doppler Anemometry ◽  
Radial Profile ◽  
Axial Flow ◽  
Power Input ◽  
Vessel Diameter ◽  
Energetic Efficiency ◽  
Turbulent Regime ◽  
Flat Bottom ◽  
Mean Velocity ◽  
Liquid Suspensions

A study was made of the pumping capacity of pitched blade impellers in a cylindrical pilot plant vessel with four standard radial baffles at the wall under a turbulent regime of flow. The pumping capacity was calculated from the radial profile of the axial flow, under the assumption of axial symmetry of the discharge flow. The mean velocity was measured using laser Doppler anemometry in a transparent vessel of diameter T = 400 mm, provided with a standard dished bottom. Three and six blade pitched blade impellers (the pitch angle varied within the interval a Îá24°; 45°ń) of impeller/vessel diameter ratio D/T = 0.36, as well as a three blade pitched blade impeller with folded blades of the same diameter, were tested. The calculated results were compared with the results of experiments mentioned in the literature, above all in cylindrical vessels with a flat bottom. Both arrangements of the agitated system were described by the impeller energetic efficiency, i.e, a criterion including in dimensionless form both the impeller energy consumption (impeller power input) and the impeller pumping effect (impeller pumping capacity). It follows from the results obtained with various geometrical configurations that the energetic efficiency of pitched blade impellers is significantly lower for configurations suitable for mixing solid-liquid suspensions (low impeller off bottom clearances) than for blending miscible liquids in mixing (higher impeller off bottom clearances).

Automatic Hex-Dominant Mesh Generation for Complex Flow Configurations

2018 ◽  
Vol 11 (6) ◽  
pp. 615-624
Author(s):  
Nihar Sawant ◽  
Soji Yamakawa ◽  
Satbir Singh ◽  
Kenji Shimada
Keyword(s):  
Mesh Generation ◽  
Complex Flow ◽  
Flow Configurations

An Overview of Stochastic Tools for Modeling Transport of Tracers in Heterogeneous Media

2003 ◽  
Author(s):  
Yoram Rubin
Keyword(s):  
Spatial Variability ◽  
Heterogeneous Media ◽  
Breakthrough Curves ◽  
Velocity Shear ◽  
Numerical Dispersion ◽  
Complex Flow ◽  
Advection Dispersion ◽  
Arbitrary Dimensions ◽  
Flow Configurations ◽  
Small Solute

Spatial variability and the uncertainty in characterizing the flow domain play an important role in the transport of contaminants in porous media: they affect the pathlines followed by solute particles, the spread of solute bodies, the shape of breakthrough curves, the spatial variability of the concentration, and the ability to quantify any of these accurately. This chapter briefly reviews some basic concepts which we shall later employ for the analysis of solute transport in heterogeneous media, and also points out some issues we shall address in the subsequent chapters. Our exposition in chapters 8-10 on contaminant transport is built around the Lagrangian and the Eulerian approaches for analyzing transport. The Eulerian approach is a statement of mass conservation in control volumes of arbitrary dimensions, in the form of the advection-dispersion equation. As such, it is well suited for numerical modeling in complex flow configurations. Its main difficulties, however, are in the assignment of parameters, both hydrogeological and geochemical, to the numerical grid blocks such that the effects of subgrid-scale heterogeneity are accounted for, and in the numerical dispersion that occurs in advection-dominated flow situations. Another difficulty is in the disparity between the scale of the numerical elements and the scale of the samples collected in the field, which makes the interpretation of field data difficult. The Lagrangian approach focuses on the displacements and travel times of solute bodies of arbitrary dimensions, using the displacements of small solute particles along streamlines as its basic building block. Tracking such displacements requires that the solute particles do not transfer across streamlines. Since such mass transfer may only occur due to pore-scale dispersion, Lagrangian approaches are ideally suited for advection-dominated situations. Let us start by considering the displacement of a small solute body, a particle, as a function of time. “Small” here implies that the solute body is much smaller than the characteristic scale of heterogeneity. At the same time, to qualify for a description of its movement using Darcy’s law, the solute body also needs to be larger than a few pores. The small dimension of the solute body ensures that it moves along a single streamline and that it does not disintegrate due to velocity shear.

Instabilities of the von Kármán Boundary Layer

2015 ◽  
Vol 67 (3) ◽  
Author(s):  
R. J. Lingwood ◽  
P. Henrik Alfredsson
Keyword(s):  
Boundary Layer ◽  
Three Dimensional ◽  
Rotating Disk ◽  
Direct Numerical Simulations ◽  
Layer Model ◽  
Complex Flow ◽  
Von Karman ◽  
Dimensional Boundary ◽  
Flow Configurations ◽  
Von Kármán

Research on the von Kármán boundary layer extends back almost 100 years but remains a topic of active study, which continues to reveal new results; it is only now that fully nonlinear direct numerical simulations (DNS) have been conducted of the flow to compare with theoretical and experimental results. The von Kármán boundary layer, or rotating-disk boundary layer, provides, in some senses, a simple three-dimensional boundary-layer model with which to compare other more complex flow configurations but we will show that in fact the rotating-disk boundary layer itself exhibits a wealth of complex instability behaviors that are not yet fully understood.

An Experimental Investigation of the Flow Through an Axial-Flow Pump

1995 ◽  
Vol 117 (3) ◽  
pp. 485-490 ◽  
Author(s):  
W. C. Zierke ◽  
W. A. Straka ◽  
P. D. Taylor
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Axial Flow ◽  
Fast Response ◽  
Complex Flow ◽  
Penn State ◽  
Response Pressure ◽  
Axial Flow Pump ◽  
Scale Experiment ◽  
High Reynolds

The high Reynolds number pump (HIREP) facility at ARL Penn State has been used to perform a low-speed, large-scale experiment of the incompressible flow of water through a two-blade-row turbomachine. The objectives of this experiment were to provide a database for comparison with three-dimensional, turbulent flow computations, to evaluate engineering models, and to improve our physical understanding of many of the phenomena involved in this complex flow field. This summary paper briefly describes the experimental facility, as well as the experimental techniques—such as flow visualization, static-pressure measurements, laser Doppler velocimetry, and both slow- and fast-response pressure probes. Then, proceeding from the inlet to the exit of the pump, the paper presents highlights of experimental measurements and data analysis, giving examples of measured physical phenomena such as endwall boundary layers, separation regions, wakes, and secondary vortical structures. In conclusion, this paper provides a synopsis of a well-controlled, larger scope experiment that should prove helpful to those who wish to use the database.

Influence of Induction Swirl and Piston Configuration on Air Flow in a Four-Stroke Model Engine

1984 ◽  
Vol 198 (2) ◽  
pp. 71-79 ◽  
Author(s):  
C Vafidis
Keyword(s):  
Velocity Distribution ◽  
Laser Doppler Anemometry ◽  
Stroke Model ◽  
Piston Bowl ◽  
Vortex Pattern ◽  
Swirl Velocity ◽  
Cyclic Variations ◽  
Model Engine ◽  
Cylinder Flow ◽  
Dead Centre

Measurements of ensemble-averaged mean, r.m.s. and cycle resolved instantaneous swirl velocities, obtained by laser—Doppler anemometry, are reported for the in-cylinder flow in a four-stroke model engine motored at 200 r/min. Variable induction swirl was created by 30° and 60° vanes located in axisymmetric and off-centre intake ports with flat and re-entrant bowl piston configurations. The results showed that the main features of the initial swirl velocity distribution, which are determined by the intake port/valve geometry, persist through the compression stroke. The swirl centre performed in all cases a helical motion whose development was a function of the clearance volume at top dead centre; the weakness of this motion made it susceptible to cyclic variations which were significantly reduced with the re-entrant piston bowl. High induction swirl resulted in lower turbulence intensity at top dead centre of compression, in the flat piston case, and more complex vortex pattern inside the re-entrant piston bowl. The angular momentum decay from inlet valve closure to top dead centre of compression was shown to depend on initial swirl ratio and velocity distribution and calculated to be about 30 and 45 per cent for the flat and re-entrant bowl piston, respectively.

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