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.

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.

scholarly journals A spectral analysis of laser Doppler anemometry turbulent flow measurements in a ship air wake

2015 ◽  
Vol 229 (12) ◽  
pp. 2309-2320 ◽  
Author(s):  
R Bardera-Mora ◽  
MA Barcala-Montejano ◽  
A Rodríguez-Sevillano ◽  
G González de Diego ◽  
M Ruiz de Sotto
Keyword(s):  
Spectral Analysis ◽  
Turbulent Flow ◽  
Laser Doppler Anemometry ◽  
Laser Doppler ◽  
Flow Measurements

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.

scholarly journals A Rotating Laser-Doppler Anemometry System for Unsteady Relative Flow Measurements in Model Centrifugal Impellers

1993 ◽  
Author(s):  
M. Abramian ◽  
J. H. G. Howard
Keyword(s):  
Laser Doppler Anemometry ◽  
Fluid Dynamic ◽  
Rotating Stall ◽  
Secondary Flows ◽  
Operating Conditions ◽  
Laser Doppler ◽  
Low Flow ◽  
Centrifugal Impeller ◽  
Flow Measurements ◽  
Relative Flow

The behaviour of the relative flow in centrifugal turbomachines is extremely complex due to the existence of various fluid dynamic phenomena and their interaction. At design and off-design operating conditions, the relative flow is subject to stationary unsteadiness which includes the flow separation and wakes associated with passage pressure gradients, secondary flows, and boundary layer stability. It is also subject to periodic unsteadiness from the rotating stall and the cyclic flow phenomena induced by the casing. This paper describes the mechanical and optical design of a rotating laser-Doppler anemometry system which allows direct measurement of the relative flow by means of an optical de-rotator. By isolating the impeller rotational frequency from the sampling frequency, it allows direct time-average measurements of the stationary behaviour of the relative flow along with the ensemble (phase)-average measurements of its periodic behaviour. Its success is demonstrated with measurements conducted in a low specific speed centrifugal impeller fitted with a single volute. Sample results of the time-averaged blade-to-blade variation of total relative velocities along with their associated turbulence intensities are reported. The (periodic) cyclic variations of the impeller exit flow, induced by the volute at low flow rates, are also presented for the suction and pressure sides.

A Rotating Laser-Doppler Anemometry System for Unsteady Relative Flow Measurements in Model Centrifugal Impellers

1994 ◽  
Vol 116 (2) ◽  
pp. 260-268 ◽  
Author(s):  
M. Abramian ◽  
J. H. G. Howard
Keyword(s):  
Laser Doppler Anemometry ◽  
Fluid Dynamic ◽  
Rotating Stall ◽  
Secondary Flows ◽  
Operating Conditions ◽  
Laser Doppler ◽  
Low Flow ◽  
Centrifugal Impeller ◽  
Flow Measurements ◽  
Relative Flow

The behavior of the relative flow in centrifugal turbomachines is extremely complex due to the existence of various fluid dynamic phenomena and their interaction. At design and off-design operating conditions, the relative flow is subject to stationary unsteadiness, which includes the flow separation and wakes associated with passage pressure gradients, secondary flows, and boundary layer stability. It is also subject to periodic unsteadiness from the rotating stall and the cyclic flow phenomena induced by the casing. This paper describes the mechanical and optical design of a rotating laser-Doppler anemometry system, which allows direct measurement of the relative flow by means of an optical derotator. By isolating the impeller rotational frequency from the sampling frequency, it allows direct time-averaged measurements of the stationary behavior of the relative flow along with the ensemble (phase)-averaged measurements of its periodic behavior. Its success is demonstrated with measurements conducted in a low specific speed centrifugal impeller fitted with a single volute. Sample results of the time-averaged blade-to-blade variation of total relative velocities along with their associated turbulence intensities are reported. The (periodic) cyclic variations of the impeller exit flow, induced by the volute at low flow rates, are also presented for the suction and pressure sides.

Spatiotemporal Characterization of a Conical Swirler Flow Field Under Strong Forcing

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
A. Lacarelle ◽  
T. Faustmann ◽  
D. Greenblatt ◽  
C. O. Paschereit ◽  
O. Lehmann ◽  
...  
Keyword(s):  
Flow Field ◽  
Swirling Flow ◽  
Flow Instability ◽  
Laser Doppler Anemometry ◽  
Helical Structure ◽  
Mean Velocity ◽  
Flow Measurements ◽  
Natural Flow ◽  
Flow Frequency

In this study, a spatiotemporal characterization of forced and unforced flows of a conical swirler is performed based on particle image velocimetry (PIV) and laser Doppler anemometry (LDA). The measurements are performed at a Reynolds number of 33,000 and a swirl number of 0.71. Axisymmetric forcing is applied to approximate the effects of thermoacoustic instabilities on the flow field at the burner inlet and outlet. The actuation frequencies are set at the natural flow frequency (Strouhal number Stf≈0.92) and two higher frequencies (Stf≈1.3 and 1.55) that are not harmonically related to the natural frequency. Phase-averaged measurement are used as a first step to visualize the coherent flow structures. Second, proper orthogonal decomposition (POD) is applied to the PIV data to characterize the effect of the actuation on the fluctuating flow. Measurements indicate a typical natural flow instability of helical nature in the unforced case. The associated induced pressure and flow oscillations travel upstream to the swirler inlet where generally fuel is injected. This observation is of critical importance with respect to the stability of the combustion. Harmonic actuation at different frequencies and amplitudes does not affect the mean velocity profile at the outlet, while the coherent velocity fluctuations are strongly influenced at both the inlet and outlet. On one hand, the dominant helical mode is replaced by an axisymmetric vortex ring if the flow is forced at the natural flow frequency. On the other hand, the natural flow frequency prevails at the outlet under forcing at higher frequencies and POD analysis indicates that the helical structure is still present. The presented results give new insight into the flow dynamics of a swirling flow burner under strong forcing.

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