scholarly journals The Influence of Swirl on the Flow Characteristics of a Reciprocating Piston-Cylinder Assembly

1980 ◽  
Vol 102 (4) ◽  
pp. 478-480 ◽  
Author(s):  
A. Morse ◽  
J. H. Whitelaw ◽  
M. Yianneskis
Keyword(s):  
Cylinder Head ◽  
Swirling Flow ◽  
Laser Doppler Anemometry ◽  
Flow Characteristics ◽  
Laser Doppler ◽  
Mean Velocity ◽  
Velocity Fluctuations ◽  
Piston Cylinder ◽  
Orthogonal Components ◽  
Significant Compression

Measurements of three orthogonal components of mean velocity and the rms values of the corresponding velocity fluctuations have been obtained by laser-Doppler anemometry in the axisymmetric swirling flow in a motored piston-cylinder assembly. The crank was rotated at 200 rpm and the inlet arrangement, a simulated open valve inclined at 60 deg to the cylinder head, provided swirl numbers at entry of approximately 0.45 and 1.20. There was no significant compression. The present results and previous results without swirl are compared.

Turbulent Flow Measurements by Laser-Doppler Anemometry in Motored Piston-Cylinder Assemblies

1979 ◽  
Vol 101 (2) ◽  
pp. 208-216 ◽  
Author(s):  
A. P. Morse ◽  
J. H. Whitelaw ◽  
M. Yianneskis
Keyword(s):  
Cylinder Head ◽  
Laser Doppler Anemometry ◽  
Laser Doppler ◽  
Cylinder Wall ◽  
Mean Velocity ◽  
Flow Measurements ◽  
Piston Bowl ◽  
Piston Cylinder ◽  
Large Vortex ◽  
Strong Vortex

Laser-Doppler anemometry has been used to quantify the mean velocity and turbulence characteristics of the isothermal, incompressible flow within a piston-cylinder arrangement motored without compression at 200 rpm and with idealized inlet geometries corresponding to a pipe and to an annular port located in the centre of the cylinder head. The results indicate that the pipe entry gives rise to a strong vortex near the piston as the indrawn air is deflected radially along the piston face and cylinder wall; this, in turn, gives rise to a weaker, counter-rotating vortex near the cylinder head which grows appreciably as the piston approaches bottom-dead-centre. With the annular-port entry, the inlet jet is angled and results in a flow pattern with a large vortex occupying nearly all of the flow space with much smaller vortices at the corners between the wall and the piston and cylinder heads. The effect of a piston bowl was also investigated for the port entry and is shown to be small.

The Flow Characteristics of a Piston-Cylinder Assembly with an Off-Centre, Open Port

1980 ◽  
Vol 194 (1) ◽  
pp. 291-299 ◽  
Author(s):  
A. P. Morse ◽  
J. H. Whitelaw ◽  
M. Yianneskis
Keyword(s):  
Cylinder Head ◽  
Laser Doppler Anemometry ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Axial Flow ◽  
Circumferential Velocity ◽  
Piston Cylinder ◽  
Radial Profiles ◽  
Intake Stroke ◽  
Open Port

Laser-Doppler anemometry has been used to measure the mean and r.m.s. values of the velocity components of the flow in a reciprocating assembly containing an off-centre, open port in the cylinder head and a flat piston. The port was inclined at an angle of 60° to the head and gave rise to a three-dimensional flow with no significant compression. The rotational speed was 200 rev/min, ensuring fully turbulent flow. The measurements were restricted to the axial and circumferential velocity components and were made on three radial planes in order to describe the flow in sufficient detail. The results are presented in the form of radial profiles and vector diagrams in both the axial and cross-stream planes. The main flow pattern on the intake stroke is of the same general shape as that previously obtained with a symmetric port, a large vortex occupying the space bounded by the indrawn jet with a much smaller vortex in the corner between the cylinder head and wall. These vortices are however no longer symmetrical about the cylinder axis, but vary in both size and intensity with circumferential position. In the cross-stream plane, the primary vortex is characterized by the presence of a stress-induced swirling motion on either side of the plane of symmetry with velocities significantly greater than the circumferential velocity of the jet. At mid-stroke, these vortices rotate counter to the jet, but at 144° ATDC, the direction of rotation reverses over part of the length of the vortex and is in the same sense as the jet motion. On the exhaust stroke, the flow patterns are relatively simple with quasi-parallel axial flow and little swirl until the port is approached, when the outgoing jet accelerates and begins to rotate in a direction opposite to its motion on the intake stroke.

Investigation into the structure of a swirling flow in a model of a vortex combustion chamber by laser doppler anemometry

2013 ◽  
Vol 39 (1) ◽  
pp. 30-32 ◽  
Author(s):  
I. S. Anufriev ◽  
Yu. A. Anikin ◽  
A. I. Fil’kov ◽  
E. L. Loboda ◽  
M. V. Agafontseva ◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Swirling Flow ◽  
Laser Doppler Anemometry ◽  
Laser Doppler ◽  
Vortex Combustion

Axisymmetric Flow in a Motored Reciprocating Engine

1978 ◽  
Vol 192 (1) ◽  
pp. 213-223 ◽  
Author(s):  
A. D. Gosman ◽  
A. Melling ◽  
J. H. Whitelaw ◽  
P. Watkins
Keyword(s):  
Laser Doppler Anemometry ◽  
Axisymmetric Flow ◽  
Flow Characteristics ◽  
Small Scale ◽  
Mean Velocity ◽  
Inlet Velocity ◽  
Reciprocating Engine ◽  
Laminar And Turbulent Flow ◽  
Flow Through ◽  
The Mean

A study was made of axisymmetric, laminar and turbulent flow in a motored reciprocating engine with flow through a cylinder head port. Measurements were obtained by laser-Doppler anemometry and predictions for the laminar case were generated by finite-difference means. Agreement between calculated and measured results is good for the main features of the flow field, but significant small scale differences exist, due partly to uncertainties in the inlet velocity distribution. The measurements show, for example, that the mean velocity field is influenced more strongly by the engine geometry than by the speed. In general, the results confirm that the calculation method can be used to represent the flow characteristics of motored reciprocating engines without compression and suggest that extensions to include compression and combustion are within reach.

Investigation of turbulent flow field in a Kenics static mixer by Laser Doppler Anemometry

2013 ◽  
Vol 67 (9) ◽  
Author(s):  
Halina Murasiewicz ◽  
Zdzislaw Jaworski
Keyword(s):  
Reynolds Number ◽  
Energy Density ◽  
Laser Doppler Anemometry ◽  
Strong Dependence ◽  
Angular Position ◽  
Laser Doppler ◽  
Energy Spectra ◽  
Static Mixer ◽  
Measurement Point ◽  
Velocity Fluctuations

AbstractThe main purpose of the present paper was to apply the Laser Doppler Anemometry (LDA) technique to measure turbulent liquid flow in a Kenics static mixer. The LDA set-up was a one-channel backscatter system with argon-ion laser. Measurements in the static mixer were carried out for three values of the Reynolds number: 5000, 10000, and 18000. Water was used as the process liquid. Values of the axial and tangential components of the local, mean, and root mean square velocities were measured inside the static mixer. It was observed that the shape of the velocity profile depends strongly on the Reynolds number, Re, as well as on the axial, h, and radial, α, position of the measurement point. Strong dependence of the velocity fluctuations on the Reynolds number was found in the investigated range of Re and the measurement point position. Furthermore, one-dimensional energy spectra of the velocity fluctuations were also obtained by means of the Fast Fourier Transform. Fluctuation spectra of the axial and tangential velocities provided information about the energy density of velocity fluctuations in the observed range of Reynolds numbers. A study of the energy spectra led to the conclusion that the energy density increases with the increasing radial distance from the mixer walls at constant values of h, Re, and α. Minor variations in the mean value of the energy density, E, were observed together with variations of the measurement point angular position, α. In addition, it was observed that an increase of the Reynolds number causes significant increase of the power spectral density.

The laser-Doppler velocimeter and its application to the measurement of turbulence

1973 ◽  
Vol 60 (2) ◽  
pp. 321-362 ◽  
Author(s):  
William K. George ◽  
John L. Lumley
Keyword(s):  
Power Spectrum ◽  
Laser Doppler ◽  
Turbulent Velocity ◽  
Laser Doppler Velocimeter ◽  
Light Sources ◽  
Mean Velocity ◽  
Velocity Fluctuations ◽  
Theoretical Predictions ◽  
Laminar And Turbulent Flow ◽  
Scattering Volume

In 1964, Yeh & Cummins demonstrated that coherent light sources could be used for the measurement of steady fluid velocities by observing the Doppler shift in the frequency of light scattered from small particles moving with the fluid. Since 1964 many investigators have attempted to extend this technique to the measurement of turbulent velocity fluctuations.A fundamental limitation on this type of velocimeter is the Doppler ambiguity introduced by the finite transit time of particles through the scattering volume, turbulent velocity fluctuations across the scattering volume, mean velocity gradients and electronic noise. A unified account of the effect of the Doppler ambiguity on the measurement of the instantaneous velocities is presented and results are interpreted using the power spectrum. The influence of the ambiguity on the measurement of other statistical quantities is also examined.Limitations on the spatial and temporal resolution imposed by the finite sampling volume are examined using the power spectrum and criteria for optimization of the response are proposed.An operational laser-Doppler velocimeter is described and measurements of spectra in both laminar and turbulent flow are presented. The experimental results are seen to be in excellent agreement with theoretical predictions.

Velocity Characteristics of Confined Coaxial Jets With and Without Swirl

1980 ◽  
Vol 102 (1) ◽  
pp. 47-53 ◽  
Author(s):  
M. A. Habib ◽  
J. H. Whitelaw
Keyword(s):  
Stokes Equations ◽  
Swirling Flow ◽  
Laser Doppler Anemometry ◽  
Velocity Ratio ◽  
Equation Model ◽  
Navier Stokes ◽  
Recirculation Region ◽  
Jet Flows ◽  
Mean Velocity ◽  
Navier Stokes Equations

Measured values of the velocity characteristics of turbulent, confined, coaxial-jet flows have been obtained, without swirl, for ratios of maximum annulus to pipe velocities of 1.0 and 3.0 and with a swirl number of 0.23 for a velocity ratio of 3.0. They were obtained by a combination of pressure probes, hot-wire and laser-Doppler anemometry. The results are compared with calculations, based on the solution of finite-difference forms of the steady, Navier-Stokes equations, and an effective-viscosity hypothesis. The measurements allow the influence of confinement and swirl to be quantified and show, for example, the increased tendency towards centerline recirculation which results from both. The results with the three types of instrumentation allow a comparison within the corner recirculation region which reveals that serious errors of interpretation of mean-velocity measurements need not arise. The two-equation model, although able to represent the non-swirling flow is less appropriate to the swirling flow and the reasons are indicated.

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.

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