Aerodynamics Study of a Linearly-Arranged 5-Swirler Array

In this experimental work, a series of tests have been conducted to further study the aerodynamics of linearly-arranged 5-swirler arrays, using Laser Doppler Velocimetry (LDV). Two major parameters have been investigated for the 5-swirler arrays in this work, including the inter-swirler spacing, and the end wall distance. An additional effect of dome recession was studied for a single swirler in order to provide some insight into the results for the 5-swirler arrays. The 5-swirler arrays with an inter-swirler spacing of 1.75D, 2D, 2.5D, and 2.75D were studied, where D is the diameter of swirler exit. For the inter-swirler spacing of 1.75D or 2D, the center swirler is shown to have a weak, large center toroidal recirculation zone (CTRZ). The swirlers next to the center swirlers have strong, compact CTRZs whereas the outer swirlers have weak, large CTRZs. Thus, starting from the center swirler, the CTRZs exhibit a large – small – large pattern in either direction. For the swirler spacing of 2.5D or 2.75D, the trend is reversed, with a strong CTRZ for the center swirler and a small – large – small CTRZ pattern. The end wall distances of 0.75D, 1D, 1.25D, and 2D cases were studied. The end wall distances are seen to affect the strength of each CTRZ and the corner swirling flow pattern, though the bulk flow structure did not change significantly. The dome recession shows a clear impact on the expansion of swirling flow generated by a single swirler. As the dome recession distance increases, the expansion angle of the swirling jet reduces significantly for the unconfined cases. A phenomenological description is discussed to understand the reason for the periodically alternating CTRZ pattern observed in the experimental results of the 5-swirler arrays.

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Downstream relaxation of velocity profiles in pipe-flow with swirl disturbances

tm - Technisches Messen ◽

10.1515/teme-2016-0029 ◽

2016 ◽

Vol 83 (12) ◽

Cited By ~ 4

Author(s):

Simon Graner ◽

Denis F. Hinz ◽

Christian Breitsamter

Keyword(s):

Cross Sections ◽

Pipe Flow ◽

Performance Indicators ◽

Laser Doppler Velocimetry ◽

Swirling Flow ◽

Flow Patterns ◽

Velocity Profiles ◽

Doppler Velocimetry ◽

Characteristic Shape ◽

And Performance

AbstractWe study characteristic flow patterns downstream of a standardized swirl disturbance generator using laser-Doppler velocimetry (LDV). To investigate the spatial development of flow patterns, we conduct LDV measurements in cross-sections located at various distances downstream from the swirl disturbance generator. Focusing on velocity profiles, decay of swirl, and performance indicators used to describe the characteristic shape of the velocity profiles, we systematically compare the experimental results with available references and various theories for decay of swirl disturbances. We find that the standardized swirl disturbance generator provides exponentially decaying swirling flow that is best captured by the theory of Steenbergen and Voskamp

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Experimental Investigation of the Flow Inside a Water Model of a Gas Turbine Combustor: Part 1—Mean and Turbulent Flowfield

Journal of Fluids Engineering ◽

10.1115/1.2817283 ◽

1995 ◽

Vol 117 (3) ◽

pp. 450-458 ◽

Cited By ~ 8

Author(s):

J. J. McGuirk ◽

J. M. L. M. Palma

Keyword(s):

Experimental Data ◽

Gas Turbine ◽

Laser Doppler Velocimetry ◽

Recirculation Zone ◽

Water Model ◽

Doppler Velocimetry ◽

Flow Conditions ◽

Gas Turbine Combustor ◽

High Turbulence ◽

The Mean

The present study examines the flow inside the water model of a gas turbine combustor, with the two main objectives of increasing the understanding of this type of flow and providing experimental data to assist the development of mathematical models. The main features of the geometry are the interaction between two rows of radially opposed jets penetrating a cross-flowing axial stream with and without swirl, providing a set of data of relevance to all flows containing these features. The results, obtained by laser Doppler velocimetry, showed that under the present flow conditions, the first row of jets penetrate almost radially into the combustor and split after impingement, giving rise to a region of high turbulence intensity and a toroidal recirculation zone in the head of the combustor. Part 1 discusses the mean and turbulent flowfield, and the detailed study of the region near the impingement of the first row of jets is presented in Part 2 of this paper.

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Effect of Dome Geometry on Swirling Flow Field Characteristics of a Counter-Rotating Radial-Radial Swirler

Volume 1B: Combustion, Fuels and Emissions ◽

10.1115/gt2013-95344 ◽

2013 ◽

Author(s):

Yi-Huan Kao ◽

Samir B. Tambe ◽

San-Mou Jeng

Keyword(s):

Flow Field ◽

Flow Structure ◽

Recirculation Zone ◽

Swirling Flow ◽

Aerodynamic Characteristics ◽

Sudden Expansion ◽

Reacting Flow ◽

Clockwise Rotation ◽

Expansion Angle ◽

Flow Field Characteristics

An experimental study has been conducted to study the effect of the dome geometry on the aerodynamic characteristics of a non-reacting flow field. The flow was generated by a counter-rotating radial-radial swirler consisting of an inner, primary swirler generating counter-clockwise rotation and an outer, secondary swirler generating clockwise rotation. The dome geometry was modified by introducing dome expansion angles of 60° and 45° with respect to the swirler centerline, in addition to the baseline case of sudden expansion (90°). The flow downstream of the swirler is confined by a 50.8mm × 50.8mm × 304.8mm (2″ × 2″ × 12″) plexiglass chamber. A two-component laser doppler velocimetry (LDV) system was used to measure the velocities in the flow field. The dome geometry is seen to have a clear impact on mean swirling flow structure near the swirler exit rather than the downstream flow field. For the configurations with 60° and 45° expansion, no corner recirculation zone is observed and the swirling flow structure is asymmetric due to the non-axisymmetric dome geometry. The cross-section area of central recirculation zone is larger for dome geometry with 60° expansion angle, as compared to the 90° and 45° cases. The configurations with 60° and 45° expansion have higher magnitudes of negative velocity inside the core of central recirculation zone, as compared to the configuration with 90° expansion angle.

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Investigation of the Behavior of Ventilated Supercavities

ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting: Volume 2, Fora ◽

10.1115/fedsm-icnmm2010-30984 ◽

2010 ◽

Cited By ~ 3

Author(s):

Ellison Kawakami ◽

Roger E. A. Arndt

Keyword(s):

Froude Number ◽

Direct Measurement ◽

Experimental Work ◽

Laser Doppler Velocimetry ◽

Cavitation Number ◽

Laser Doppler ◽

Doppler Velocimetry ◽

Flow Choking ◽

Ventilated Cavitation ◽

Supercavitating Vehicle

A study has been carried out at the Saint Anthony Falls Laboratory (SAFL) to investigate various aspects of the flow physics of a supercavitating vehicle. For the experimental work presented here, artificial supercavitation behind a sharp-edged disk was investigated for various model configurations. Results regarding supercavity shape, closure, and ventilation requirements versus Froude number are presented. Conducting experiments in water tunnels introduces blockage effects that are not present in nature. As a result, effects related to flow choking are also discussed. Various methods for computing ventilated cavitation number, including direct measurement of pressure, Laser Doppler Velocimetry, and use of previous numerical results, were compared. Results obtained are similar in character to previous results from various authors, but differ significantly in measured values. Supercavitation parameters, especially the minimum obtainable cavitation number are strongly affected by tunnel blockage.

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Experimental Investigation of Confined Swirling Flow and Its Interaction With a Bluff Body

Journal of Fluids Engineering ◽

10.1115/1.4044482 ◽

2019 ◽

Vol 142 (1) ◽

Author(s):

Zhang Tianxing ◽

Mohamed Alshehhi ◽

Lyes Khezzar ◽

Yakang Xia ◽

Nabil Kharoua

Keyword(s):

Flow Structure ◽

Pipe Flow ◽

Laser Doppler Velocimetry ◽

Bluff Body ◽

Swirling Flow ◽

Reynolds Numbers ◽

Working Fluid ◽

Doppler Velocimetry ◽

Mean Square ◽

The Mean

Abstract Detailed laser Doppler velocimetry (LDV) measurements of profiles of mean axial and tangential velocities and their corresponding root-mean-square (RMS) components in confined turbulent swirling pipe flow with and without the presence of a conical bluff body have been conducted. The working fluid was water and the Reynolds number based on the bulk velocity inside the pipe was equal to 40,850. The main focus of the study was to document the interaction between turbulent swirling flow inside a pipe and in the presence of a conical bluff body. The flow structure was found in all cases to be composed of a forced-free vortex. The swirl decay was exponential for Reynolds numbers of 40,850 and 14,450. The effect of the presence of the bluff body on the flow is limited to a short region upstream of it; so that the effect on the flow structure and strength of swirl upstream can be considered negligible. The flow around the bluff body adopts a different structure where the mean axial and tangential velocities tend to assume uniform profiles with turbulence activity limited to the region close to the surface of the bluff body.

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Effect of the Flare Expansion Angle on the Mean and Dynamic Behavior of Swirling Flow Generated by a Counter Rotating Radial-Radial Swirler Using a Water Test Rig

Volume 4B: Combustion, Fuels and Emissions ◽

10.1115/gt2015-43470 ◽

2015 ◽

Cited By ~ 2

Author(s):

Wessam Estefanos ◽

Samir Tambe ◽

San-Mou Jeng

Keyword(s):

Dynamic Behavior ◽

High Speed ◽

Recirculation Zone ◽

Swirling Flow ◽

Flow Instability ◽

Reverse Flow ◽

Test Rig ◽

Expansion Angle ◽

Water Test ◽

The Mean

A series of experiments have been conducted to study the effect of the flare expansion angle on the mean and unsteady behavior of the non-reacting swirling flow using a water test rig. The flow was examined in water using a 3X model of a counter rotating radial-radial swirler. Three flares having expansion angles of 30.9°, 35.9° and 40.9° with respect to the swirler centerline were tested. 2D high speed Particle Image Velocimetry (PIV) measurements were employed to study the instantaneous and mean velocity fields. Tests were conducted at a Reynolds number equivalent to an air pressure drop of 4% for the corresponding 1X model of the swirler under atmospheric conditions. The flare expansion angle was found to have a clear impact on the mean, turbulent and dynamic behavior of the swirling flow. With the increase in the flare expansion angle, the width of the Center Toroidal Recirculation Zone (CTRZ) increased. The length and width of the Corner Recirculation Zone decreased with increasing the flare angle. For the 30.9° flare, the high turbulence regions extended further axially compared to the other two flares. Strong flow instability was observed on the boundaries of the reverse flow zones. A temporal FFT approach was used to obtain the dominant frequencies of flow instability based on the instantaneous velocity data. The dominant frequency of this instability was slightly lower for the 30.9° flare angle. High turbulent kinetic energy (TKE) was located in the vicinity of the unstable shear layers originating from the CTRZ and CRZ. The TKE reached its maximum near the center for the 30.9° flare and near the walls for the 35.9° and 40.9° flares. The phase angle difference between the high TKE regions was 3.14 radians, indicating a circumferential mode of instability. The obtained results give a clear explanation on the mechanisms driving the flow instability and how these mechanisms change with the change in the flare angle. These results also serve as a tool to validate CFD models.

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