Supersonic Through-Flow Fan Blade Cascade Studies

2003 ◽  
Vol 125 (5) ◽  
pp. 796-805 ◽  
Author(s):  
Christopher J. Chesnakas ◽  
Wing F. Ng
Keyword(s):  
Incidence Angle ◽  
Leading Edge ◽  
Navier Stokes ◽  
Pressure Distributions ◽  
Blade Cascade ◽  
Viscous Losses ◽  
Through Flow ◽  
Wave Patterns ◽  
Loss Coefficients ◽  
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). Measurements were made at an inlet Mach number of 2.36 over a 15 deg 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 convected 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.

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.

scholarly journals Effects of a Single Blade Incidence Angle Offset on Adjacent Blades in a Linear Cascade

Processes ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1974
Author(s):  
Jiří Fürst ◽  
Martin Lasota ◽  
Jan Lepicovsky ◽  
Josef Musil ◽  
Jan Pech ◽  
...  
Keyword(s):  
High Speed ◽  
Static Pressure ◽  
Incidence Angle ◽  
Blade Loading ◽  
Linear Cascade ◽  
Pressure Distributions ◽  
Blade Cascade ◽  
Loading Function ◽  
Stationary Approach ◽  
Dimensional Section

The paper presents a numerical and experimental investigation of the effect of incindence angle offset in a two-dimensional section of a flat blade cascade in a high-speed wind tunnel. The aim of the current work is tp determine the aerodynamic excitation forces and approximation of the unsteady blade-loading function using a quasi-stationary approach. The numerical simulations were performed with an in-house finite-volume code built on the top of the OpenFOAM framework. The experimental data were acquired for regimes corresponding to the numerical setup. The comparison of the computational and experimental results is shown for the static pressure distributions on three blades and upstream and downstream of the cascade. The plot of the aerodynamic moments acting on all five blades shows that the adjacent blades are significantly influenced by the angular offset of the middle blade.

Boundary layer leading-edge receptivity to sound at incidence angles

2001 ◽  
Vol 444 ◽  
pp. 383-407 ◽  
Author(s):  
ERCAN ERTURK ◽  
THOMAS C. CORKE
Keyword(s):  
Acoustic Waves ◽  
Stokes Equations ◽  
Incidence Angle ◽  
Leading Edge ◽  
Quantitative Agreement ◽  
Navier Stokes ◽  
Angle Of Incidence ◽  
Sound Waves ◽  
Nose Radius ◽  
Navier Stokes Equations

The leading-edge receptivity to acoustic waves of two-dimensional parabolic bodies was investigated using a spatial solution of the Navier–Stokes equations in vorticity/streamfunction form in parabolic coordinates. The free stream is composed of a uniform flow with a superposed periodic velocity fluctuation of small amplitude. The method follows that of Haddad & Corke (1998) in which the solution for the basic flow and linearized perturbation flow are solved separately. We primarily investigated the effect of frequency and angle of incidence (−180° [les ] α2 [les ] 180°) of the acoustic waves on the leading-edge receptivity. The results at α2 = 0° were found to be in quantitative agreement with those of Haddad & Corke (1998), and substantiated the Strouhal number scaling based on the nose radius. The results with sound waves at angles of incidence agreed qualitatively with the analysis of Hammerton & Kerschen (1996). These included a maximum receptivity at α2 = 90°, and an asymmetric variation in the receptivity with sound incidence angle, with minima at angles which were slightly less than α2 = 0° and α2 = 180°.

Investigation of G4-73 Centrifugal Fan Airfoil Stall Characteristics

2011 ◽  
Vol 383-390 ◽  
pp. 4221-4226
Author(s):  
Song Ling Wang ◽  
Zhe Liu ◽  
Lei Zhang
Keyword(s):  
Stokes Equations ◽  
Incidence Angle ◽  
Leading Edge ◽  
Suction Side ◽  
Navier Stokes ◽  
Centrifugal Fan ◽  
Reliable Operation ◽  
Safe Operation ◽  
Navier Stokes Equations ◽  
Strong Vortex

It’s of great significance for safe and reliable operation of fan to research on the stall characteristics of the airfoil. The 2D non-compressible Reynolds-Averaged Navier-Stokes equations was built to simulate the flow around the airfoil of G4-73No.8D centrifugal fan, a detailed numerical simulation under different angles has been carried out which based on the Realizable turbulence model with Fluent. The numerical results show that the smaller of the flow rate, the bigger incidence angle is, when the incidence angle is bigger than the critical incidence angle, the suction side stall appears. According simulation the airfoil stall appears when the incidence angle is -28°, with the increasing of the negative incidence angle, the separation point gradually moves to the leading edge. There is a strong vortex which locates at suction side =0.5,the alternating stress on the blade which caused by vortex will make the blade fatigue. If the incidence angle is less than -20°,there is no flow separation, therefore, to ensure the safe operation of the fan, the incidence angle should be less than -20°.

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.

Optimization of a Fan Blade Cascade Using the Parametric Flow Solver Turb’Opty

2006 ◽  
Author(s):  
S. Moreau ◽  
S. Aubert ◽  
G. Grondin ◽  
P. Ferrand
Keyword(s):  
Stokes Equations ◽  
Lift Coefficient ◽  
Taylor Series Expansion ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Flow Solver ◽  
Free Jet ◽  
Engine Cooling ◽  
Blade Cascade ◽  
Fan Blade

The parameterized CFD solver Turb’Opty™, based on a Taylor series expansion to high order derivatives of the solution of the discretized Navier-Stokes equations, has been successfully applied to the full geometric and flow parameterization of an engine cooling fan blade cascade. The coupling of a recently developed genetic algorithm and the post-processor Turb’Post™ has also yielded a multi-objective optimization of the original Valeo airfoil. A representative geometry of the Pareto front has then been prototyped and tested. Significant improvement of the lift coefficient has been obtained at all incidences. Comparisons with direct Turb’Flow™ cascade results have validated the accuracy of the parameterized solutions and shown the same trend as the free-jet measurements.

Parametic Study of a Fan Blade Cascade Using a New Parametric Flow Solver Turb’Opty

2003 ◽  
Author(s):  
S. Moreau ◽  
S. Aubert ◽  
M. N’Diaye ◽  
P. Ferrand
Keyword(s):  
Stokes Equations ◽  
Taylor Series Expansion ◽  
Navier Stokes ◽  
Reference Solution ◽  
Navier Stokes Equations ◽  
Flow Solver ◽  
Engine Cooling ◽  
Blade Cascade ◽  
Order Expansion ◽  
Fan Blade

The newly developed parameterized CFD solver Turb’Opty™, based on a Taylor series expansion to high order derivatives of the solutions of the discretized Navier-Stokes equations, has been successfully applied to the turbulent incompressible flow field of an engine cooling fan blade cascade. Comparisons with the classical CFD results have validated the accuracy of the parameterized solutions obtained by a simple polynomial reconstruction around a reference solution with respect to two different flow parameters for two different cases: a fifth order expansion with respect to these coupled parameters for a frozen turbulence and a first order expansion with respect to each parameter for a variable turbulence. The latter is found to have a better accuracy and a larger range of application. Starting from a reference solution obtained with another commercial code has also been successfully tested. Finally, further industrial perspectives of turbomachinery global optimization are finally demonstrated by coupling this method with a simple genetic algorithm.

The Interaction Between the Impeller and Casing in a Small-Size Turbo-Compressor

2002 ◽  
Author(s):  
D.-W. Kim ◽  
Youn J. Kim
Keyword(s):  
Static Pressure ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Reference Method ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Pressure Distributions ◽  
Loss Coefficients ◽  
Compressible Turbulent Flow ◽  
Turbo Compressor

The effects of casing shape on the performance and the interaction between the impeller and casing in a small-size turbo-compressor are investigated. Numerical analysis is conducted for the compressor with circular and single volute casings from inlet to discharge nozzle. In order to predict the flow pattern inside the entire impeller, vaneless diffuer and casing, calculations with multiple frames of reference method between the rotating and stationery parts of the domain are carried out. For compressible turbulent flow fields, the continuity and three-dimensional time-averaged Navier-Stokes equations are employed. To evaluate the performance of two types of casings, the static pressure and loss coefficients are obtained with various flow rates. Also, static pressure distributions around casings are studied for different casing shapes, which are very important to predict the distribution of radial load. To prove the accuracy of numerical results, measurements of static pressure around casing and pressure difference between the inlet and outlet of the compressor are performed for the circular casing. Comparison of these results between the experimental and numerical analyses are conducted, and reasonable agreement is obtained.

scholarly journals Boundary Layer and Navier-Stokes Analysis of a NASA Controlled-Diffusion Compressor Blade

1990 ◽  
Author(s):  
Y. K. Ho ◽  
G. J. Walker ◽  
P. Stow
Keyword(s):  
Boundary Layer ◽  
Turbulence Modeling ◽  
Separation Bubble ◽  
Leading Edge ◽  
Adverse Pressure Gradient ◽  
Compressor Blade ◽  
Navier Stokes ◽  
Laminar Separation ◽  
Controlled Diffusion ◽  
Pressure Distributions

Performance calculations for a NASA controlled-diffusion compressor blade have been carried out with a coupled inviscid-boundary layer code and a time-marching Navier-Stokes solver. Comparisons with experimental test data highlight and explain the strengths and limitations of both these computational methods. The boundary layer code gives good results at and near design conditions. Loss predictions however deteriorated at off-design incidences. This is mainly due to a problem with leading edge laminar separation bubble modelling; coupled with an inability of the calculations to grow the turbulent boundary layer at a correct rate in a strong adverse pressure gradient. Navier-Stokes loss predictions on the other hand are creditable throughout the whole incidence range, except at extreme positive incidence where turbulence modeling problems similar to those of the coupled boundary layer code are observed. The main drawback for the Navier-Stokes code is the slow rate of convergence for these low Mach number cases. Plans are currently under review to address this problem. Both codes give excellent predictions of the blade surface pressure distributions for all the cases considered.

Supersonic Through-Flow Fan Blade Cascade Studies: Part II — Riblet Effects

2000 ◽  
Author(s):  
Todd Ninnemann ◽  
Wing F. Ng
Keyword(s):  
Pressure Profile ◽  
Virginia Tech ◽  
Loss Coefficient ◽  
Test Case ◽  
Control Case ◽  
Flow Conditions ◽  
Equivalent Thickness ◽  
Blade Cascade ◽  
Through Flow ◽  
Fan Blade

An experimental study to determine the effects of riblets on the performance of the Supersonic Throughflow Fan (STF) cascade blades was performed. The unique flow conditions of the STF provided a new application of using riblets to reduce aerodynamic losses. The cascade was tested in the Virginia Tech intermittent wind tunnel facility, where the Mach and Reynolds (based on chord) numbers were 2.36 and 4.8 × 106, respectively. The riblet sheets were symmetric v-grooved type and were applied onto the blade surfaces. Three different riblet heights were tested: 0.023, 0.033, and 0.051 mm. Riblet testing was conducted at design incidence as well as at off-design conditions (incidence angles: +5, −10 deg). To evaluate the performance of the riblets on the blades, a Pitot-static probe was used to measure the wake profile downstream of the cascade. The resultant total pressure profile was then integrated to obtain an overall mass-averaged loss coefficient. This loss coefficient was compared with a control test case where an equivalent thickness of smooth material is applied to the blade. Results show that at the design incidence, the riblet sheet with a height of 0.033 mm provides the optimal benefit, with a reduction of 8.5% in loss coefficient compared to the control case. Smaller effects were measured at the off-design conditions.

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