Numerical and Experimental Investigations of the Three-Dimensional-Flow Structure of Tandem Cascades in the Sidewall Region

2014 ◽  
Vol 136 (7) ◽  
Author(s):  
Martin Böhle ◽  
Thomas Frey
Keyword(s):  
Three Dimensional ◽  
Experimental Investigations ◽  
Aerodynamic Load ◽  
Flow Topology ◽  
Three Dimensional Flow ◽  
Flow Losses ◽  
Spacing Ratio ◽  
Flow Phenomena ◽  
2D Flow ◽  
Tandem Cascades

Tandem blades can be superior to single blades, particularly when large turning angles are required. This is well documented in the open literature and many investigations have been performed on the 2D-flow of tandem cascades to date. However, much less information on the flow near the sidewalls is available. Thus, the question arises as to how the geometry of a tandem cascade should be chosen near the sidewall in order to minimize the flow losses for large turning angles. The present work examines the 3D-flow field in the region of the sidewall of two high turning tandem cascades. A large spacing ratio was chosen for the forward blade of the first tandem cascade ((t/l)1=1.92). The second tandem cascade possessed a smaller spacing ratio for the forward blades ((t/l)1=1.0). Both cascades had the same total spacing ratio of t/l=0.6. Flow phenomena, such as the corner stall of the 3D boundary layer near the sidewall, are examined using both numerical and experimental methods. The empirical correlations of Lieblein and Lei are applied. The flow topology of both tandem cascades is explained and the locations of loss onset are identified. In addition, oil pictures from experiments and streamline pictures of the numerical simulations are shown and discussed for the flow close to the sidewalls. Finally, design rules such as the aerodynamic load splitting and the spacing ratio of the forward- and aft-blades, etc. are taken into account. The examinations are performed for tandem cascades designed for flow turning of approximately 50 deg at a Reynolds number of 8×105. The tandem cascades consist of NACA65 blades with circular camber lines and an aspect ratio of b/l=1.0.

Flow Structure of Tandem Cascades in the Region of the Sidewalls

2013 ◽  
Author(s):  
Thomas Frey ◽  
Martin Böhle
Keyword(s):  
Flow Structure ◽  
Experimental Investigations ◽  
Flow Topology ◽  
Minimal Loss ◽  
Spacing Ratio ◽  
Flow Phenomena ◽  
2D Flow ◽  
The Individual ◽  
Individual Profiles ◽  
Tandem Cascades

Numerical and experimental investigations about tandem blades have often been performed for the 2D flow of tandem cascades. The open literature suggests that tandem blades may be superior to single blades, especially for large turning angles. However, the investigations up to now never involved the losses, arising at the sidewall. Less information about the flow structure near the sidewall are available. This raises the question whether the geometry that generates minimal losses for the 2D flow also generates minimal losses near the sidewall for large turning angles. This paper deals with the 3D flow in the region of the sidewall of a high turning tandem cascade with low aspect ratio. For the numerical and experimental investigation two tandem cascades were designed using empirical correlations of Lieblein and Lei. Starting with these tandem cascades the configuration of the individual profiles is determined that generates minimal loss at the wall. Based on the flow topology the loss generation is identified and explained. The images of the flow topology are created on the basis of numerical and experimental oil pictures. The procedure and results are discussed in detail. In particular the occurrence of flow phenomena like corner stall of the 3D boundary layer is discussed. Finally design rules for the spacing ratio of the forward and afterward blades as well as the percent pitch of the blades are given. The examinations are performed with tandem cascades turning the flow from approximately 50° at a Reynolds number of 8 · 105. In every cascade the load split is constant (50%). The profiles are NACA65 with circular camber lines.

Investigation of Vortex Reacting Flows in Asymmetric Meso Scale Combustor

2013 ◽  
Vol 388 ◽  
pp. 246-250 ◽  
Author(s):  
Mostafa Khaleghi ◽  
Mazlan A. Wahid ◽  
Mohsin M. Seis ◽  
Aminuddin Saat
Keyword(s):  
Flame Structure ◽  
Three Dimensional ◽  
Reacting Flows ◽  
Experimental Investigations ◽  
Flame Stability ◽  
Three Dimensional Flow ◽  
Asymmetric Vortex ◽  
Wide Range ◽  
Basic Characteristics ◽  
Exceptional Stability

In the current study computational and experimental investigations of a turbulent asymmetric vortex flame is presented. The three dimensional flow fields have been described using a computational methodology that impalements the kε turbulence model. The computational model is validated for isothermal flow. Moreover, the visible flame structure was captured by direct photography at a wide range of equivalence ratios in order to emphasize the exceptional stability of such flame. The mechanism of flame stability and interaction with the forced vortex field is preliminarily discussed. Finally, the basic characteristics of the asymmetric vortex flames are concluded.

Interferometric CT measurement of three-dimensional flow phenomena on shock waves and vortices discharged from open ends

Shock Waves ◽  
2003 ◽  
Vol 13 (3) ◽  
pp. 179-190 ◽  
Author(s):  
H. Honma ◽  
M. Ishihara ◽  
T. Yoshimura ◽  
K. Maeno ◽  
T. Morioka
Keyword(s):  
Shock Waves ◽  
Three Dimensional ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Flow Phenomena ◽  
Ct Measurement

Tomographic PIV in the Near Field of a Swirl-Stabilised Fuel Injector

2018 ◽  
Author(s):  
Adrian Spencer ◽  
Mark Brend ◽  
Daniel Butcher ◽  
David Dunham ◽  
Liangta Cheng ◽  
...  
Keyword(s):  
Near Field ◽  
Measurement Techniques ◽  
Three Dimensional ◽  
Isothermal Flow ◽  
Structure Identification ◽  
Experimental Investigations ◽  
Fuel Injector ◽  
Flow Topology ◽  
Tomographic Piv ◽  
Velocity Statistics

The isothermal flow fields of injectors have undergone several computational and experimental investigations using point and planar measurement techniques,. Within the swirl induced vortex breakdown region it is only LES that has been able to predict fully the presence of a three dimensional helical vortex structure for a particular injector, and in certain conditions (no central fuel jet), a precessing vortex core. These structures can be elucidated from point and planar measurements and favorable comparisons of velocity statistics between experiment and LES predictions strengthen these findings. However, volumetric, 3-component measurement of velocity data has not been widely available to provide conclusive evidence of the exact three dimensional nature of the vortex structures that exist. An experimental setup utilizing time resolved tomographic PIV on a water flow rig is described in this paper. This is used to provide as high-quality aerodynamic study as possible of a single stream radially-fed air swirl gaseous fuel injector. The level of accuracy of the tomographic PIV technique is demonstrated by calculating the divergence of the velocity field as well as validating the results against a comprehensive 2 and 3 component standard PIV velocity database and other measurement techniques and predictions. Structure identification methods have been employed to visualise and understand the complex flow topology within the near field of the injector. The change in topology with and without the stabilising central jet is further investigated and agrees with findings of planar PIV results. While the velocity error associated with the tomo-PIV results is higher than the planar results the data agree well within the identified uncertainty bounds and are complimentary in understanding the flow field structure. Thus a full volumetric aerodynamic survey is available for the first time on this isothermal flow case.

Explicit Algebraic Reynolds-stress Modeling of Pressure-induced Separating Flows in the Presence of Sidewalls

2021 ◽  
Author(s):  
Abdelouahab Mohammed Taifour ◽  
Julien Weiss ◽  
Louis Dufresne
Keyword(s):  
Reynolds Stress ◽  
Test Section ◽  
Three Dimensional ◽  
Wind Tunnel Test ◽  
Shear Stresses ◽  
Mean Flow ◽  
Flow Topology ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Good Agreement

Abstract RANS approach is used to simulate the steady state of a family of pressure-induced turbulent separation bubbles in the presence of sidewalls. Different turbulence models are employed with a specific emphasis on the BaSeLine Explicit Algebraic Reynolds Stress Model (BSL-EARSM) and the simulations are compared with experimental data. The separation and reattachment of a flat-plate turbulent boundary layer is generated through a combination of adverse and favorable pressure gradients (APG-FPG) by numerically reproducing the geometry of the wind-tunnel test section used for the experiments. Three cases are considered, a large (LB) and a medium (MB) bubble presenting mean backflow, and a small bubble (SB) without mean-flow reversal. This is achieved by varying the streamwise position of the APG/FPG transition. Good agreement between the BSL-EARSM-computed solutions and the experimental results are obtained for wall-pressure and skin-friction distributions on the centerline plane of the test section as well as for the overall three-dimensional flow topology. However, both detachment and reattachment are predicted too early and the bubble length is slightly overestimated for Cases LB and MB. For Case LB, the streamwise Reynolds stress is estimated fairly well but its production is somewhat delayed. Normal and shear stresses are in good agreement with the experiments in the upstream part of the bubble but are significantly over-estimated in the reattachment region. The k ?? ! Shear-Stress Transport (SST) model with the so-called reattachment modification performs better than the other tested linear-eddy-viscosity models but it is still unable to reproduce accurately the three-dimensional flow topology even for the 'simplest' case SB. Overall, the results suggest that BSL-EARSM is the most suitable turbulence model for this flow configuration.

Experimental and Numerical Investigation of Three-Dimensional Viscous Flows and Vortex Motion Inside an Annular Compressor Blade Row

1991 ◽  
Vol 113 (2) ◽  
pp. 198-206 ◽  
Author(s):  
H. E. Gallus ◽  
C. Hah ◽  
H. D. Schulz
Keyword(s):  
Numerical Investigation ◽  
Vortex Motion ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Compressor Cascade ◽  
Complex Flow ◽  
Three Dimensional Flow ◽  
Navier Stokes Equation ◽  
Dimensional Flow ◽  
Flow Phenomena

A detailed experimental and numerical investigation was carried out to examine the three-dimensional flow field, secondary flows, and vortex motion in an annular compressor cascade. Various flow visualizations near the blade surface and endwalls, wall static pressure and loss measurements, as well as hot-film and hot-wire measurements inside the blade boundary layers were performed at various flow rates to understand the complex flow phenomena. A Reynolds-averaged Navier–Stokes equation was solved to investigate the flow numerically. The detailed comparison between measurement and numerical prediction indicates that the complex three-dimensional flow phenomena (corner stall, vortex motion, radial mixing, etc.) are very well predicted with the numerical method.

Experimental Study on Hydrodynamic Performance of Mini-AUV in Non-Uniform Flow Field

2019 ◽  
Author(s):  
Jiayuan Zhuang ◽  
Jian Cao ◽  
Yumin Su ◽  
Lei Zhang ◽  
Xianzhao Yu
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Lateral Force ◽  
Uniform Flow ◽  
Hydrodynamic Performance ◽  
Experimental Investigations ◽  
Complex Flow ◽  
Three Dimensional Flow ◽  
Drift Angle ◽  
Current Profiler

Abstract Experimental investigations of hydrodynamic performance of mini-AUV in non-uniform flow field were conducted in the basin of Harbin Engineering University, the revolved body and flat body of mini-AUV model were tested respectively. The three dimensional flow fields were generated by local jet of the underwater pump, and circulated in the basin. The three dimensional velocity distributions at different positions were measured by a Doppler current profiler. The three component balance was used to measure the drag, lateral force and yawing moment acting on the mini-AUV models depending on drift angle in the flow field, and the influence of complex flow field to the hydrodynamic performance of mini-AUV indicated that drag was not sensitive to drift angle and yawing moment was increased obviously. The conducted experiments could supply reference to the maneuverability research of mini-AUV in real marine environments in the future.

scholarly journals Three-dimensional flow phenomena in a wire-wrapped 37-pin fuel bundle for SFR

2015 ◽  
Vol 47 (5) ◽  
pp. 523-533 ◽  
Author(s):  
Jae-Ho Jeong ◽  
Jin Yoo ◽  
Kwi-Lim Lee ◽  
Kwi-Seok Ha
Keyword(s):  
Three Dimensional ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Fuel Bundle ◽  
Flow Phenomena

Numerical Calculation of Wall Pressure Fluctuations in a Centrifugal Fan

2004 ◽  
Author(s):  
Sandra Velarde-Sua´rez ◽  
Rafael Ballesteros-Tajadura ◽  
Juan Pablo Hurtado-Cruz ◽  
Carlos Santolaria-Morros
Keyword(s):  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Power Spectra ◽  
Wall Pressure ◽  
Operating Conditions ◽  
Numerical Code ◽  
Experimental Investigations ◽  
Centrifugal Fan ◽  
Wall Pressure Fluctuations ◽  
Flow Phenomena

In this work, a numerical code has been applied in order to obtain the wall pressure fluctuations at the volute of an industrial centrifugal fan. The numerical results have been contrasted using previous experimental investigations carried out in the same machine. A three-dimensional numerical simulation of the complete unsteady flow on the whole impeller-volute configuration has been carried out using the computational fluid dynamics code FLUENT®. This code has been employed to calculate the time-dependent pressure both in the impeller and in the volute. In this way, the pressure fluctuations in some locations over the volute wall have been obtained. The power spectra of these fluctuations have been calculated, showing an important peak at the blade passing frequency. The amplitude of this peak presents the highest values near the volute tongue, but the spatial pattern over the volute extension is different depending on the operating conditions. The code has successfully simulated the volute pressure fluctuations due to the aerodynamic field, capturing the main flow phenomena such as the jet-wake effects and the impeller-volute interaction.

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