Effect of Annulus Flow Conditions on Turbine Rim Seal Ingestion

2019 ◽  
Author(s):  
Donato M. Palermo ◽  
Feng Gao ◽  
John W. Chew ◽  
Paul F. Beard
Keyword(s):  
Velocity Ratio ◽  
Axial Flow ◽  
Passive Scalar ◽  
External Flow ◽  
Rotor Blades ◽  
Flow Structures ◽  
Flow Conditions ◽  
Sealing Performance ◽  
Annulus Flow ◽  
The Mean

Abstract A systematic study of sealing performance for a chute style turbine rim seal using URANS methods is reported. This extends previous studies from a configuration without external flow in the main annulus to cases with a circumferentially uniform axial flow and vane generated swirling annulus flow (but without rotor blades). The study includes variation of the mean seal-to-rotor velocity ratio, main annulus-to-rotor velocity ratio, and seal clearance. The effects on the unsteady flow structures and the degree of main annulus flow ingestion into the rim seal cavity are examined. Sealing effectiveness is quantified by modeling a passive scalar, and the timescales for the convergence of this solution are considered. It has been found that intrinsic flow unsteadiness occurs in most cases, with the presence of vanes and external flow modifying, the associated flow structures and frequencies. Some sensitivities to the annulus flow conditions are identified. The circumferential pressure asymmetry generated by the vanes has a clear influence on the flow structure but does not lead to higher ingestion rates than the other conditions studied.

Improvement of Stalling Characteristics of an Axial-Flow Fan by Radial-Vaned Air-Separators

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Nobuyuki Yamaguchi ◽  
Masayuki Ogata ◽  
Yohei Kato
Keyword(s):  
Solid Wall ◽  
Axial Flow ◽  
Internal Flow ◽  
Rotor Blades ◽  
Relative Location ◽  
Flow Conditions ◽  
Axial Flow Fan ◽  
Light Load ◽  
Stall Prevention ◽  
Air Separator

An improved construction of air-separator device, which has radial-vanes embedded within its inlet circumferential opening with their leading-edges facing the moving tips of the fan rotor-blades so as to scoop the tip flow, was investigated with respect to the stall-prevention effect on a low-speed, single-stage, lightly loaded, axial-flow fan. Stall-prevention effects by the separator layout, relative location of the separator to the rotor-blades, and widths of the openings of the air-separator inlet and exit were parametrically surveyed. As far as the particular fan is concerned, the device together with the best relative location has proved to be able to eliminate effectively the stall zone having existed in the original solid-wall characteristics, which has confirmed the promising potential of the device. Guidelines were obtained from the data for optimizing relative locations of the device to the rotor-blades, maximizing the stall-prevention effect of the device, and minimizing the axial size of the device for a required stall-prevention effect, at least for the particular fan and possibly for fans of similar light-load fans. The data suggest the changing internal flow conditions affected by the device conditions.

An initial assessment of bed destabilization risk past vegetation patches using instrumented particles

2021 ◽  
Author(s):  
Yi Xu ◽  
Valyrakis Manousos ◽  
Panagiotis Michalis
Keyword(s):  
Initial Assessment ◽  
Flow Structures ◽  
Clear Water ◽  
Flow Conditions ◽  
Flow Parameters ◽  
Water Conditions ◽  
The Mean ◽  
Acoustic Doppler Velocimetry ◽  
Patch Density ◽  
Vegetation Patches

<p>Instream vegetation may alter the mean and turbukent flow fields leading to destabilizing riverbed surface, under certain flow conditions. In particular, recent research on instream vegetation hydrodynamics and ecohydrogeomorphology has focused on how energetic flow structures and bulk flow parameters downstream a vegetation may result in riverbed destabilization. This study, demonstrated the application of a 20mm novel instrumented particle in recording entrainment rates downstream simulated vegetation patches of distinct densities, at various distances downstream these. A patch of 6mm acrilic cylinders is used to simulate the emergent vegetation having the same diameter (12cm) and different porosities or densities (void volume equal to 1.25%, 3.15%, 6.25%, 11.25%, and 17.25%). The flow velocity near the instrumented particle is recorded using acoustic Doppler velocimetry (ADV) with appropriate seeding, under clear water conditions. Preliminary results are presented with focus on the effect of vegetation patch density on the flow field and subsequent effects on particle entrainment rates and implications for bed surface destabilisation.</p>

Presentation of a Blade-Design Method for Axial-Flow Turbines, Including Design and Test Results of a Typical Axial-Flow Stage

1960 ◽  
Vol 82 (1) ◽  
pp. 19-26
Author(s):  
F. Baumgartner ◽  
R. Amsler
Keyword(s):  
Design Method ◽  
Axial Flow ◽  
Rate Of Change ◽  
Rotor Blades ◽  
Test Results ◽  
Blade Loading ◽  
Blade Row ◽  
Consistent Manner ◽  
The Mean ◽  
Typical Design

A method is presented to determine the shape of stationary nozzle blades and rotor blades for an axial-flow-type turbine in a generally consistent manner based on the concept of aerodynamic blade loading. The mean blade load is a typical design parameter which predominantly determines the blade curvature. It depends in particular on the rate of change of momentum across the blade row. By applying the design method, airfoil shapes are obtained which satisfy the momentum requirements regardless of what blade-load distribution is assumed as long as the mean blade load remains constant. A specific application of the design method is described and test data are presented which show that good agreement between design goal and test results was achieved.

scholarly journals Wall-Modelled Large Eddy Simulations of Axial Turbine Rim Sealing

2020 ◽  
Author(s):  
Donato M. Palermo ◽  
Feng Gao ◽  
Dario Amirante ◽  
John W. Chew ◽  
Anna Bru Revert ◽  
...  
Keyword(s):  
Eddy Viscosity ◽  
Passive Scalar ◽  
Rotor Blades ◽  
Computational Time ◽  
Scalar Concentration ◽  
Large Eddy ◽  
Annulus Flow ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes ◽  
Good Agreement

Abstract This paper presents WMLES simulations of a chute type turbine rim seal. Configurations with an axisymmetric annulus flow and with nozzle guide vanes fitted (but without rotor blades) are considered. The passive scalar concentration solution and WMLES are validated against available data in the literature for uniform convection and a rotor-stator cavity flow. The WMLES approach is shown to be effective, giving significant improvements over an eddy viscosity turbulence model, in prediction of rim seal effectiveness compared to research rig measurements. WMLES requires considerably less computational time than wall-resolved LES, and has the potential for extension to engine conditions. All WMLES solutions show rotating inertial waves in the chute seal. Good agreement between WMLES and measurements for sealing effectiveness in the configuration without vanes is found. For cases with vanes fitted the WMLES simulation shows less ingestion than the measurements, and possible reasons are discussed.

Wall-Modelled Large Eddy Simulations of Axial Turbine Rim Sealing

2021 ◽  
Author(s):  
Donato Maria Palermo ◽  
Feng Gao ◽  
Dario Amirante ◽  
John W. Chew ◽  
Anna Bru Revert ◽  
...  
Keyword(s):  
Eddy Viscosity ◽  
Passive Scalar ◽  
Rotor Blades ◽  
Computational Time ◽  
Scalar Concentration ◽  
Large Eddy ◽  
Annulus Flow ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes ◽  
Good Agreement

Abstract This paper presents WMLES simulations of a chute type turbine rim seal. Configurations with an axisymmetric annulus flow and with nozzle guide vanes fitted (but without rotor blades) are considered. The passive scalar concentration solution and WMLES are validated against available data in the literature for uniform convection and a rotor-stator cavity flow. The WMLES approach is shown to be effective, giving significant improvements over an eddy viscosity turbulence model, in prediction of rim seal effectiveness compared to research rig measurements. WMLES requires considerably less computational time than wall-resolved LES, and has the potential for extension to engine conditions. All WMLES solutions show rotating inertial waves in the chute seal. Good agreement between WMLES and measurements for sealing effectiveness in the configuration without vanes is found. For cases with vanes fitted the WMLES simulation shows less ingestion than the measurements, and possible reasons are discussed.

Currentmeter Errors under Pulsating flow Conditions

1967 ◽  
Vol 9 (1) ◽  
pp. 45-54 ◽  
Author(s):  
P. Jepson
Keyword(s):  
Unsteady Flow ◽  
Theoretical Approach ◽  
Axial Flow ◽  
Pulsating Flow ◽  
Flow Conditions ◽  
Mean Velocity ◽  
Registration Errors ◽  
Flow Fluctuations ◽  
The Mean ◽  
Flow Pulsations

The paper deals with the effect of unsteady flow on the velocity registration of current-meters. In the first section of the paper, experiments are described which show that axial flow pulsations cause currentmeters to over-estimate and that flow fluctuations transverse to the mean velocity generally cause under-registration by amounts depending on the flow and meter parameters. From these tests general comments are made concerning the choice of metering station and to a lesser extent meter design. The second section is theoretical and deals with the effects of axially pulsating flows. It has been possible, using simple aerodynamic principles, to show how the meter design can be improved to minimize registration errors. The agreement between this theoretical approach and the registration errors obtained from experiment is fair.

The Turbulent Incompressible Jet in a Curved Coflow

1996 ◽  
Vol 118 (2) ◽  
pp. 300-306 ◽  
Author(s):  
M. V. O¨tu¨gen ◽  
F. Girlea ◽  
P. M. Sforza
Keyword(s):  
Turbulence Intensity ◽  
Velocity Ratio ◽  
Axial Flow ◽  
Streamwise Velocity ◽  
Half Width ◽  
Outer Side ◽  
Mean Velocity ◽  
Streamline Curvature ◽  
The Mean ◽  
Pronounced Peak

The effects of small streamline curvature on the growth and axial flow development of a turbulent incompressible jet in a curved coflow was investigated experimentally. The jet streamline curvature was achieved by introducing the initially round jet tangentially into a stream flowing through a curved channel of square cross-section. The jet issued from a straight pipe and had a fully developed velocity profile at the exit plane. The jet Reynolds number and the coflow-to-jet-velocity ratio were 4300 and 0.11, respectively. A single component laser Doppler anemometer was used to measure the streamwise velocity. Axial mean velocity and turbulence intensity profiles were measured at various streamwise locations in both the plane of curvature and the surface perpendicular to the plane of curvature. The results indicate that the jet growth and turbulence intensity are influenced by the small streamline curvature. The growth rate of the curved jet in the plane of curvature is slightly increased compared to that of a straight jet. However, the growth of the same curved jet is suppressed in the plane perpendicular to the plane of curvature. In the plane of curvature, the inner jet half-width is larger than the outer jet half-width. The mean velocity profiles in this plane are nearly Gaussian when the lateral distance is normalized by the respective inner and outer side jet half-widths. The axial turbulence intensity profiles show asymmetry in the plane of curvature with a pronounced peak on the outer side of the jet.

scholarly journals Forensic Investigation of Four Monitored Green Infrastructure Inlets

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1787
Author(s):  
Leena J. Shevade ◽  
Franco A. Montalto
Keyword(s):  
Measurement Uncertainty ◽  
Green Infrastructure ◽  
Stormwater Management ◽  
Catchment Area ◽  
Low Flow ◽  
Inflow Rate ◽  
Forensic Investigation ◽  
Flow Conditions ◽  
The Mean

Green infrastructure (GI) is viewed as a sustainable approach to stormwater management that is being rapidly implemented, outpacing the ability of researchers to compare the effectiveness of alternate design configurations. This paper investigated inflow data collected at four GI inlets. The performance of these four GI inlets, all of which were engineered with the same inlet lengths and shapes, was evaluated through field monitoring. A forensic interpretation of the observed inlet performance was conducted using conclusions regarding the role of inlet clogging and inflow rate as described in the previously published work. The mean inlet efficiency (meanPE), which represents the percentage of tributary area runoff that enters the inlet was 65% for the Nashville inlet, while at Happyland the NW inlet averaged 30%, the SW inlet 25%, and the SE inlet 10%, considering all recorded events during the monitoring periods. The analysis suggests that inlet clogging was the main reason for lower inlet efficiency at the SW and NW inlets, while for the SE inlet, performance was compromised by a reverse cross slope of the street. Spatial variability of rainfall, measurement uncertainty, uncertain tributary catchment area, and inlet depression characteristics are also correlated with inlet PE. The research suggests that placement of monitoring sensors should consider low flow conditions and a strategy to measure them. Additional research on the role of various maintenance protocols in inlet hydraulics is recommended.

scholarly journals Quantifying the Effects of Wave—Current Interactions on Tidal Energy Resource at Sites in the English Channel Using Coupled Numerical Simulations

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3625
Author(s):  
Jon Hardwick ◽  
Ed B. L. Mackay ◽  
Ian G. C. Ashton ◽  
Helen C. M. Smith ◽  
Philipp R. Thies
Keyword(s):  
Wave Model ◽  
Tidal Energy ◽  
English Channel ◽  
Flow Conditions ◽  
Mean Flow ◽  
Radiation Stress ◽  
Large Wave ◽  
Stress Gradients ◽  
The Mean ◽  
Flow Power

Numerical modeling of currents and waves is used throughout the marine energy industry for resource assessment. This study compared the output of numerical flow simulations run both as a standalone model and as a two-way coupled wave–current simulation. A regional coupled flow-wave model was established covering the English Channel using the Delft D-Flow 2D model coupled with a SWAN spectral wave model. Outputs were analyzed at three tidal energy sites: Alderney Race, Big Roussel (Guernsey), and PTEC (Isle of Wight). The difference in the power in the tidal flow between coupled and standalone model runs was strongly correlated to the relative direction of the waves and currents. The net difference between the coupled and standalone runs was less than 2.5%. However, when wave and current directions were aligned, the mean flow power was increased by up to 7%, whereas, when the directions were opposed, the mean flow power was reduced by as much as 9.6%. The D-Flow Flexible Mesh model incorporates the effects of waves into the flow calculations in three areas: Stokes drift, forcing by radiation stress gradients, and enhancement of the bed shear stress. Each of these mechanisms is discussed. Forcing from radiation stress gradients is shown to be the dominant mechanism affecting the flow conditions at the sites considered, primarily caused by dissipation of wave energy due to white-capping. Wave action is an important consideration at tidal energy sites. Although the net impact on the flow power was found to be small for the present sites, the effect is site specific and may be significant at sites with large wave exposure or strong asymmetry in the flow conditions and should thus be considered for detailed resource and engineering assessments.

scholarly journals Effect of Mean Velocity-to-Critical Velocity Ratios on Bed Topography and Incipient Motion in a Meandering Channel: Experimental Investigation

Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 883
Author(s):  
Nargess Moghaddassi ◽  
Seyed Habib Musavi-Jahromi ◽  
Mohammad Vaghefi ◽  
Amir Khosrojerdi
Keyword(s):  
Experimental Investigation ◽  
Critical Velocity ◽  
Velocity Ratio ◽  
Scour Depth ◽  
Incipient Motion ◽  
Mean Velocity ◽  
Straight Path ◽  
Meandering Channel ◽  
Bed Topography ◽  
The Mean

As 180-degree meanders are observed in abundance in nature, a meandering channel with two consecutive 180-degree bends was designed and constructed to investigate bed topography variations. These two 180-degree mild bends are located between two upstream and downstream straight paths. In this study, different mean velocity-to-critical velocity ratios have been tested at the upstream straight path to determine the meander’s incipient motion. To this end, bed topography variations along the meander and the downstream straight path were addressed for different mean velocity-to-critical velocity ratios. In addition, the upstream bend’s effect on the downstream bend was investigated. Results indicated that the maximum scour depth at the downstream bend increased as a result of changing the mean velocity-to-critical velocity ratio from 0.8 to 0.84, 0.86, 0.89, 0.92, 0.95, and 0.98 by, respectively, 1.5, 2.5, 5, 10, 12, and 26 times. Moreover, increasing the ratio increased the maximum sedimentary height by 3, 10, 23, 48, 49, and 56 times. The upstream bend’s incipient motion was observed for the mean velocity-to-critical velocity ratio of 0.89, while the downstream bend’s incipient motion occurred for the ratio of 0.78.

Sign in / Sign up

Export Citation Format

Share Document