Experimental Study on the Three Dimensional Unsteady Flow in a Counter-Rotating Axial Flow Fan

An analysis is presented which treats the noise generation from an axial flow fan row by given forces including the effects of a moving medium. The linearization of Euler’s equations to yield tractable problems for fan noise is discussed. The three-dimensional problem is decomposed into several two-dimensional problems. Finally, full details are given of a two-dimensional analysis to predict the amounts of acoustic energy, at the blade passing frequency and its harmonics, radiated up and downstream of a blade row due to its interaction with a neighboring row.

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Modeling of three dimensional unsteady flow effects in axial flow turbine rotors

Mechanics Research Communications ◽

10.1016/s0093-6413(98)00003-2 ◽

1998 ◽

Vol 25 (1) ◽

pp. 15-24 ◽

Cited By ~ 1

Author(s):

Eui Soo Yoon ◽

Byung Nam Kim ◽

Myung Kyoon Chung

Keyword(s):

Unsteady Flow ◽

Three Dimensional ◽

Axial Flow ◽

Turbine Rotors ◽

Flow Effects

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Extensive Experimental Study of Circumferential Single Groove in an Axial Flow Compressor

Volume 2D: Turbomachinery ◽

10.1115/gt2014-26859 ◽

2014 ◽

Cited By ~ 5

Author(s):

Jichao Li ◽

Feng Lin ◽

Sichen Wang ◽

Juan Du ◽

Chaoqun Nie ◽

...

Keyword(s):

Experimental Study ◽

Unsteady Flow ◽

Axial Compressor ◽

Axial Flow ◽

Leakage Flow ◽

Tip Leakage Flow ◽

Good Tool ◽

Stall Margin ◽

Casing Treatment ◽

Tip Leakage

Circumferential single-groove casing treatment becomes an interesting topic in recent few years, because it is a good tool to explore the interaction between the groove and the flow in blade tip region. The stall margin improvement (SMI) as a function of the axial groove location has been found for some compressors, such a trend cannot be predicted by steady high-fidelity CFD simulations. Recent efforts show that to catch such a trend, multi-passage, unsteady flow simulations are needed as the stalling mechanism itself involves cross-passage flows and unsteady dynamics. This indicates a need to validate unsteady numerical simulation results. In this paper, an extensive experimental study of a total of fifteen single casing grooves in a low-speed axial compressor rotor is presented, the groove location varies from 0.4% to 98.3% of axial tip chord are tested. The unsteady pressure data both at casing and at the blade wake with different groove locations are measured and processed, including the movement of trajectory of tip leakage flow, the evolution of unsteadiness of tip leakage flow (UTLF), the unsteady spectrum signature during the stall process, and the outlet unsteady flow characteristic along the span. These data provide a case study for validation of the unsteady CFD results, and may be helpful for further interpretation on the stalling mechanism affected by circumferential casing grooves.

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Turbulent Flow Between Two Disks Contrarotating at Different Speeds

Journal of Turbomachinery ◽

10.1115/1.2836656 ◽

1996 ◽

Vol 118 (2) ◽

pp. 408-413 ◽

Cited By ~ 8

Author(s):

M. Kilic ◽

X. Gan ◽

J. M. Owen

Keyword(s):

Experimental Study ◽

Reynolds Number ◽

Unsteady Flow ◽

Turbulent Flow ◽

Boundary Layers ◽

Axial Flow ◽

Radial Component ◽

Velocity Measurements ◽

Type Flow ◽

Radial Outflow

This paper describes a combined computational and experimental study of the turbulent flow between two contrarotating disks for −1 ≤ Γ ≤ 0 and Reφ ≈ 1.2 × 106, where Γ is the ratio of the speed of the slower disk to that of the faster one and Reφ is the rotational Reynolds number. The computations were conducted using an axisymmetric elliptic multigrid solver and a low-Reynolds-number k–ε turbulence model. Velocity measurements were made using LDA at nondimensional radius ratios of 0.6 ≤ x ≤ 0.85. For Γ = 0, the rotor–stator case, Batchelor-type flow occurs: There is radial outflow and inflow in boundary layers on the rotor and stator, respectively, between which is an inviscid rotating core of fluid where the radial component of velocity is zero and there is an axial flow from stator to rotor. For Γ = −1, antisymmetric contrarotating disks, Stewartson-type flow occurs with radial outflow in boundary layers on both disks and inflow in the viscid nonrotating core. At intermediate values of Γ, two cells separated by a streamline that stagnates on the slower disk are formed: Batchelor-type flow and Stewartson-type flow occur radially outward and inward, respectively, of the stagnation streamline. Agreement between the computed and measured velocities is mainly very good, and no evidence was found of nonaxisymmetric or unsteady flow.

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Experimental and Computational Study of the Unsteady Flow in a 1.5 Stage Axial Turbine With Emphasis on the Secondary Flow in the Second Stator

Volume 1: Turbomachinery ◽

10.1115/98-gt-254 ◽

1998 ◽

Cited By ~ 14

Author(s):

Ralf E. Walraevens ◽

Heinz E. Gallus ◽

Alexander R. Jung ◽

Jürgen F. Mayer ◽

Heinz Stetter

Keyword(s):

Unsteady Flow ◽

Secondary Flow ◽

Computational Study ◽

Three Dimensional ◽

Cross Flow ◽

Axial Flow ◽

Time Dependent ◽

Flow Structures ◽

Mean Flow ◽

Dependent Flow

A study of the unsteady flow in an axial flow turbine stage with a second stator blade row is presented. The low aspect ratio blades give way to a highly three-dimensional flow which is dominated by secondary flow structures. Detailed steady and unsteady measurements throughout the machine and unsteady flow simulations which include all blade rows have been carried out. The presented results focus on the second stator flow. Secondary flow structures and their origins are identified and tracked on their way through the passage. The results of the time-dependent secondary velocity vectors as well as flow angles and Mach number distributions as perturbation from the time-mean flow field are shown in cross-flow sections and azimuthal cuts throughout the domain of the second stator. At each location the experimental and numerical results are compared and discussed. A good overall agreement in the time-dependent flow behaviour as well as in the secondary flow structures is stated.

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