Flow Field Analysis and Nearfield Acoustic Signature Reduction of a Stationary Fan Blade Array

2020 ◽  
Author(s):  
Syed Qasim Zaheer ◽  
Peter Disimile
Keyword(s):  
Flow Field ◽  
Vortex Shedding ◽  
Leading Edge ◽  
Pressure Side ◽  
Validation Data ◽  
Array Configuration ◽  
Blade Cascade ◽  
Fan Blade ◽  
The Impact ◽  
Blade Leading Edge

Abstract A highly cambered and loaded stationary fan blade cascade of an in-service centrifugal fan is analyzed in this research work at flow conditions corresponding to design point operation of subject fan. The configuration of enclosed blade cascade includes upstream and downstream ducts. A preliminary analysis of flow variables and nearfield acoustic spectra is carried out experimentally which then provided boundary conditions and validation data for an extensive numerical analysis using Embedded Large Eddy Simulation turbulence model in ANSYS Fluent 19.0 ® environment. The comprehensive analysis of flow field and nearfield aeroacoustics of blade array configuration reveals vortex shedding from blade leading edge and its interaction with pressure side surface of adjacent blade becomes one of major source in the aeroacoustics signature of blade array. The vortex shedding frequency and the frequency of upstream turbulence interaction with blade leading edge are identified. A novel method of placing rectangular cavity on pressure side of blade array to suppress the impact of impingement of leading-edge vortex via cavity acoustic wave is explored. The numerical results reveal a reduction in noise by 6dB encouraging the efficacy of this method as a passive technique to reduce aeroacoustics signature of researched blade array configuration.

scholarly journals Influence of Blade Leading-Edge Shape on Rotating-Stalled Flow Characteristics in a Centrifugal Pump Impeller

2020 ◽  
Vol 10 (16) ◽  
pp. 5635
Author(s):  
Hongying Luo ◽  
Ran Tao ◽  
Jiandong Yang ◽  
Zhengwei Wang
Keyword(s):  
Flow Field ◽  
Centrifugal Pump ◽  
Incidence Angle ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Rotating Stall ◽  
Pump Impeller ◽  
The Impact ◽  
Centrifugal Pump Impeller ◽  
Blade Leading Edge

Rotating stall, which is a common phenomenon in turbomachinery, strongly relates to the flow rate condition. In centrifugal impellers, rotating stall was induced by the incidence angle on blade leading-edge at partial-load. The blade leading-edge shape also influences the rotating stall because of the subtle change of local flow-field. In this study, the influence of blade leading-edge shape on rotating-stalled flow characteristics was studied in a six-blade centrifugal pump impeller. The stall pattern was “alternating”: Three passages were stalled, three passages were well-behaved, and the stalled and well-behaved passages occurred alternately. The stalled flow characteristics can be studied without the interruption of stall cell movement. Four types of blade leading-edge (blunt, sharp, ellipse, and round) were numerically compared based on the initial typical impeller and the numerical–experimental verification. The numerical comparison shows that the leading-edge shape has a strong influence on the stalled flow pattern, velocity, pressure, turbulence kinetic energy, and flow-induced noise inside impellers. The blunt and sharp leading-edge impellers had a similar internal pattern; the ellipse and round leading-edge impellers were also similar in the internal flow-field. Pressure pulsation analysis showed more obvious differences among these impellers. The main frequency and the pulsation peak–peak values were completely different because of the slight leading-edge shape differences. It revealed the impact of leading-edge geometry on the transient flow-field change under the same incidence angle conditions. It also provided reference for influencing or controlling the rotating stall by blade profile design.

scholarly journals Aerothermal Investigations of Mixing Flow Phenomena in Case of Radially Inclined Ejection Holes at the Leading Edge

1999 ◽  
Author(s):  
Dieter E. Bohn ◽  
Karsten A. Kusterer
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Gas Turbines ◽  
Leading Edge ◽  
Suction Side ◽  
Pressure Side ◽  
Blade Surface ◽  
Cooling Fluid ◽  
Flow Phenomena ◽  
Vortex Systems

A leading edge cooling configuration is investigated numerically by application of a 3-D conjugate fluid flow and heat transfer solver, CHT-Flow. The code has been developed at the Institute of Steam and Gas Turbines, Aachen University of Technology. It works on the basis of an implicit finite volume method combined with a multi-block technique. The cooling configuration is an axial turbine blade cascade with leading edge ejection through two rows of cooling holes. The rows are located in the vicinity of the stagnation line, one row is on the suction side, the other row is on the pressure side. The cooling holes have a radial ejection angle of 45°. This configuration has been investigated experimentally by other authors and the results have been documented as a test case for numerical calculations of ejection flow phenomena. The numerical domain includes the internal cooling fluid supply, the radially inclined holes and the complete external flow field of the turbine vane in a high resolution grid. Periodic boundary conditions have been used in the radial direction. Thus, end wall effects have been excluded. The numerical investigations focus on the aerothermal mixing process in the cooling jets and the impact on the temperature distribution on the blade surface. The radial ejection angles lead to a fully three dimensional and asymmetric jet flow field. Within a secondary flow analysis it can be shown that complex vortex systems are formed in the ejection holes and in the cooling fluid jets. The secondary flow fields include asymmetric kidney vortex systems with one dominating vortex on the back side of the jets. The numerical and experimental data show a good agreement concerning the vortex development. The phenomena on the suction side and the pressure side are principally the same. It can be found that the jets are barely touching the blade surface as the dominating vortex transports hot gas under the jets. Thus, the cooling efficiency is reduced.

Internal Flow Analysis in a Two-Channel Pump Used for Salt Transportation

2018 ◽  
Author(s):  
Jiaqi Wang ◽  
Xianwu Luo ◽  
Wanming Li ◽  
Bin Ji
Keyword(s):  
Particle Concentration ◽  
Flow Analysis ◽  
Internal Flow ◽  
Leading Edge ◽  
Pressure Side ◽  
Operation Condition ◽  
Static State ◽  
Erosion Risk ◽  
Salt Particle ◽  
Blade Leading Edge

Two-channel pumps usually have very complicated flow field due to the special impeller geometry. The present paper treats the internal flow analysis based on numerical simulation so as to investigate the pumping performance and passage erosion for a two-channel centrifugal pump used for transporting salt particles. The static state flows are calculated by applying RANS method and k-omega SST turbulence model. The numerical results indicate that there are strong circulation flows near the impeller inlet and blade pressure side, and zones with high turbulent kinetic energy near impeller exit when the pump is operated under the designed flow rate i.e. Qd. Pressure decay is also found at the rear part of blade pressure side. At the operation condition of 1.3Qd, the internal flow becomes better. Further, the numerical analysis based on Eulerian-Lagrangian method shows the trajectory of salt particle, salt particle concentration and erosion rate in the pump. It is noted that the salt particles go smoothly in the flow passage due to the large section size of the pump, and there is severe erosion at the blade leading edge and the wall of volute casing due to strong impingement and high particle concentration. Thus, these areas such as blade leading edge and the wall of volute casing are the zones with high erosion risk in the two-channel pump.

Effects of Flow Injection From Outer Casing Upon Turbine Nozzle Vane Flow Field

2002 ◽  
Author(s):  
K. Funazaki ◽  
C. F. F. Favaretto ◽  
T. Tanuma
Keyword(s):  
Flow Field ◽  
Flow Injection ◽  
Three Dimensional ◽  
Leading Edge ◽  
Main Stream ◽  
Flow Angle ◽  
Aerodynamic Loss ◽  
Nozzle Vane ◽  
Design Variables ◽  
The Impact

In the present paper steady three-dimensional numerical calculations were performed in order to investigate the effects of flow injection from the outer casing upon turbine nozzle vane flow field. Several test cases were analyzed by applying different nozzle vane configurations such as the blade lean, injection slot width and distance from the leading edge. Numerical simulations were conducted considering the no injection case, 5% and 10% main stream flow injection from the outer casing. The impact of the flow injection design variables and the blade lean angle on the aerodynamic loss in terms of the energy loss coefficient and the outlet flow angle were analyzed through a parametric study.

An Impact of Various Shroud Bleed Slot Configurations and Cavity Vanes on Compressor Map Width and the Inducer Flow Field

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Subenuka Sivagnanasundaram ◽  
Stephen Spence ◽  
Juliana Early ◽  
Bahram Nikpour
Keyword(s):  
Flow Field ◽  
Incidence Angle ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Operating Conditions ◽  
Choked Flow ◽  
Recirculating Flow ◽  
Heavy Duty Diesel ◽  
Compressor Map ◽  
The Impact

This paper describes an investigation of map width enhancement and a detailed analysis of the inducer flow field due to various bleed slot configurations and vanes in the annular cavity of a turbocharger centrifugal compressor. The compressor under investigation is used in a turbocharger application for a heavy duty diesel engine of approximately 400 hp. This investigation has been undertaken using a computational fluid dynamics (CFD) model of the full compressor stage, which includes a manual multiblock-structured grid generation method. The influence of the bleed slot flow on the inducer flow field at a range of operating conditions has been analyzed, highlighting the improvement in surge and choked flow capability. The impact of the bleed slot geometry variations and the inclusion of cavity vanes on the inlet incidence angle have been studied in detail by considering the swirl component introduced at the leading edge by the recirculating flow through the slot. Further, the overall stage efficiency and the nonuniform flow field at the inducer inlet have been also analyzed. The analysis revealed that increasing the slot width has increased the map width by about 17%. However, it has a small impact on the efficiency, due to the frictional and mixing losses. Moreover, adding vanes in the cavity improved the pressure ratio and compressor performance noticeably. A detail analysis of the compressor with cavity vanes has also been presented.

Measurements of Hub Flow Interaction on Film Cooled Nozzle Guide Vane in Transonic Annular Cascade

2012 ◽  
Author(s):  
Lamyaa A. El-Gabry ◽  
Ranjan Saha ◽  
Jens Fridh ◽  
Torsten Fransson
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Film Cooling ◽  
Guide Vane ◽  
Leading Edge ◽  
Field Measurements ◽  
Co2 Concentration ◽  
Pressure Side ◽  
Trailing Edge ◽  
Nozzle Guide

An experimental study has been performed in a transonic annular sector cascade of nozzle guide vanes to investigate the aerodynamic performance and the interaction between hub film cooling and mainstream flow. The focus of the study is on the endwalls, specifically the interaction between the hub film cooling and the mainstream. Carbon dioxide (CO2) has been supplied to the coolant holes to serve as tracer gas. Measurements of CO2 concentration downstream of the vane trailing edge can be used to visualize the mixing of the coolant flow with the mainstream. Flow field measurements are performed in the downstream plane with a 5-hole probe to characterize the aerodynamics in the vane. Results are presented for the fully cooled and partially cooled vane (only hub cooling) configurations. Data presented at the downstream plane include concentration contour, axial vorticity, velocity vectors, and yaw and pitch angles. From these investigations, secondary flow structures such as the horseshoe vortex, passage vortex, can be identified and show the cooling flow significantly impacts the secondary flow and downstream flow field. The results suggest that there is a region on the pressure side of the vane trailing edge where the coolant concentrations are very low suggesting that the cooling air introduced at the platform upstream of the leading edge does not reach the pressure side endwall, potentially creating a local hotspot.

An Impact of Various Shroud Bleed Slot Configurations and Cavity Vanes on Compressor Map Width and the Inducer Flow Field

2011 ◽  
Author(s):  
Subenuka Sivagnanasundaram ◽  
Stephen Spence ◽  
Juliana Early ◽  
Bahram Nikpour
Keyword(s):  
Flow Field ◽  
Incidence Angle ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Operating Conditions ◽  
Choked Flow ◽  
Recirculating Flow ◽  
Heavy Duty Diesel ◽  
Compressor Map ◽  
The Impact

This paper describes an investigation of map width enhancement and a detailed analysis of the inducer flow field due to various bleed slot configurations and vanes in the annular cavity of a turbocharger centrifugal compressor. The compressor under investigation is used in a turbocharger application for a heavy duty diesel engine of approximately 400hp. This investigation has been undertaken using a CFD model of the full compressor stage which includes a manual multi-block structured grid generation method. The influence of the bleed slot flow on the inducer flow field at a range of operating conditions has been analysed, highlighting the improvement in surge and choked flow capability. The impact of the bleed slot geometry variations and the inclusion of cavity vanes on the inlet incidence angle have been studied in detail by considering the swirl component introduced at the leading edge by the recirculating flow through the slot. Further, the overall stage efficiency and the non-uniform flow field at the inducer inlet have been also analysed. The analysis revealed that increasing the slot width has increased the map width by about 17%. However, it has a small impact on the efficiency due to the frictional and mixing losses. Moreover, adding vanes in the cavity improved the pressure ratio and compressor performance noticeably. A detail analysis of the compressor with cavity vanes has also been presented.

scholarly journals Experimental measurements of the flow field around a film-cooled blade leading edge using particle image velocimetry

2018 ◽  
Vol 10 (10) ◽  
pp. 168781401880290
Author(s):  
José Omar Dávalos Ramírez ◽  
Juan Carlos García Castrejón ◽  
Francisco Carrillo Pereyra ◽  
Carlos Ponce Corral ◽  
Carlos Felipe Ramírez Espinoza ◽  
...  
Keyword(s):  
Particle Image Velocimetry ◽  
Flow Field ◽  
Particle Image ◽  
Leading Edge ◽  
Cooling Flow ◽  
Image Velocimetry ◽  
Secondary Vortices ◽  
Velocity Turbulence ◽  
Cooled Blade ◽  
Blade Leading Edge

In this article, particle image velocimetry studies were conducted in a low-speed wind tunnel to investigate the effects of blowing ratio and blade span in terms of the characteristics of the flow field around a film-cooled blade leading edge. The measurements were performed at 20%, 40%, 60%, and 80% of blade span and blowing ratios of M = 0.5, M = 0.75, M = 1, M = 1.5, and M = 2. Velocity, turbulence intensity, and structure of vortices during the interaction between cooling flow and mainstream were analyzed in detail. The analysis shows a significant increase in mainstream velocity at low blowing ratios, M < 1. Peaks of turbulence were observed at low- and high-span locations. Aerodynamical losses are expected at higher blowing ratios due to the formation of secondary vortices near the outgoing jet. These vortices were a consequence of velocity gradients at this zone.

Impact of Main and Splitter Blade Leading Edge Contour on the Performance of High Pressure Ratio Centrifugal Compressors

2014 ◽  
Author(s):  
Rodrigo R. Erdmenger ◽  
Vittorio Michelassi
Keyword(s):  
High Pressure ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Tip Clearance ◽  
Flow Coefficient ◽  
Centrifugal Compressors ◽  
Operating Range ◽  
High Pressure Ratio ◽  
The Impact ◽  
Blade Leading Edge

The impact of leading edge sweep in an attempt to reduce shock losses and extend the stall margin on axial compressors has been extensively studied, however only a few studies have looked at understanding the impact of leading edge contouring on the performance of centrifugal compressors. The present work studies the impact of forward and aft sweep on the main and splitter blade leading edge of a generic high flow coefficient and high pressure ratio centrifugal compressor design and the impact on its overall peak efficiency, pressure ratio and operating range. The usage of aft sweep on the main blade led to an increase of the pressure ratio and efficiency, however it also led to a reduction of the stable operating range of the impeller analyzed. The forward sweep cases analyzed where the tip leading edge was displaced axially forward showed a slight increase in pressure ratio, and a significant increase on operating range. The impact of leading edge sweep on the sensitivity of the impeller performance to tip clearance was also studied. The impeller efficiency was found to be less sensitive to an increase of tip clearance for both aft and forward sweep cases studied. The forward sweep cases studied also showed a reduced sensitivity from operating range to tip clearance. The studies conducted on the splitter leading edge profile indicate that aft sweep may help to increase the operating range of the impeller analyzed by up to 16% while maintaining similar pressure ratio and efficiency characteristics of the impeller. The improvement of operating range obtained with the leading edge forward sweep and splitter aft sweep was caused by a reduction of the interaction of the tip vortex of the main blade with the splitter tip, and a reduction of the blockage caused by this interaction.

Supersonic Through-Flow Fan Blade Cascade Studies: Part I — Baseline Cascade

2000 ◽  
Author(s):  
Christopher J. Chesnakas ◽  
Wing F. Ng
Keyword(s):  
Incidence Angle ◽  
Leading Edge ◽  
Navier Stokes ◽  
Nasa Lewis Research ◽  
Pressure Distributions ◽  
Blade Cascade ◽  
Viscous Losses ◽  
Through Flow ◽  
Wave Patterns ◽  
Fan Blade

An investigation has been performed of the flow in a supersonic through-flow fan blade cascade. The blade shapes are those of the baseline supersonic through-flow fan (STF) under investigation at the NASA Lewis Research Center. Measurements were made at an inlet Mach number of 2.36 over a 15° range of incidence. Flowfield wave patterns were recorded using spark shadowgraph photography and steady-state instrumentation was used to measure blade surface pressure distributions and downstream flowfield. From these measurements, the integrated loss coefficients are presented as a function of incidence angle along with analysis indicating the source of losses in the STF cascade. The results are compared with calculations made using a two-dimensional, cell-centered, finite-volume, Navier-Stokes code with upwind options. Good general agreement is found at design conditions, with lesser agreement at off-design conditions. Analysis of the leading edge shock shows that the leading edge radius is a major source of losses in STF blades. Losses from the leading edge bluntness are converted downstream into the blade wake, and are difficult to distinguish from viscous losses. Shock losses are estimated to account for 70% to 80% of the losses in the STF cascade.

Sign in / Sign up

Export Citation Format

Share Document