Three Dimensional Characteristics of Turbulent Wakes Behind Rotors of Axial Flow Turbomachinery

1976 ◽  
Vol 98 (2) ◽  
pp. 218-227 ◽  
Author(s):  
R. Raj ◽  
B. Lakshminarayana
Keyword(s):  
Three Dimensional ◽  
Axial Flow ◽  
Decay Rates ◽  
Experimental Investigations ◽  
Mean Velocity ◽  
Rotor Wake ◽  
Turbulent Wakes ◽  
Stress Maximum ◽  
Wake Model ◽  
Rotor Profiles

Analytical and experimental investigations of the characteristics of three-dimensional turbulent wakes downstream of a turbomachinery rotor are reported in this paper. An approximate quasi-three-dimensional turbulent wake model for turbomachinery rotor is developed and compared with the cascade and isolated airfoil wake models. The rotor wake model is capable of predicting the decay of mean component of radial and streamwise velocities as a function of rotor geometry, speed of rotation, and the turbulence properties of the flow field. A rotation parameter based on similarity analysis is derived. The velocity profiles in both the radial and cylindrical planes are coupled together. Measurement of mean velocities (U¯n, U¯s, U¯r), turbulent intensities and stresses (un2¯, us2¯, ur2¯, usun¯, unur¯, usur¯) is carried out using a triple sensor hot wire probe in a stationary system at various axial and radial locations downstream of the rotor. Profiles of mean and turbulent quantities are obtained. Semi-theoretical expressions for the decay rates of the defect in mean velocity, turbulence intensity, and Reynolds stress (maximum values) with distance downstream of the rotor are derived. The experimental data on the rotor wake are compared with that of an isolated airfoil and cascade of airfoils. The investigation suggests that rotor wake decays much faster than the cascade or an isolated airfoil wake.

Experimental Investigation of a Free Round Jet with Dean Vortices

2014 ◽  
Vol 9 (2) ◽  
pp. 128-135
Author(s):  
Maria Litvinenko ◽  
Yuriy Litvinenko ◽  
Grigory Kozlov ◽  
Valentin Vikhorev
Keyword(s):  
Experimental Investigation ◽  
Three Dimensional ◽  
Experimental Investigations ◽  
Acoustic Excitation ◽  
Hot Wire ◽  
Curved Channel ◽  
Mean Velocity ◽  
Round Jet ◽  
Smoke Visualization ◽  
Dean Vortices

Results of the experimental investigations of free round jet with Dean vortices formed in curved channel are presented. Hot-wire anemometry measurements of three-dimensional mean velocity profile were performed, smoke visualization pictures cross and longitudinal sections at nozzle exit and downstream were obtained. The features of jet development at acoustic excitation of 40 Hz are shown

scholarly journals Numerical Prediction of Wakes in Cascades and Compressor Rotors Including the Effects of Mixing: Part II — Rotor Passage Flow and Wakes Including the Effects of Spanwise Mixing

1991 ◽  
Author(s):  
N. Suryavamshi ◽  
B. Lakshminarayana
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Axial Flow ◽  
Radial Component ◽  
Navier Stokes ◽  
Mean Velocity ◽  
Compressor Rotor ◽  
Entire Flow ◽  
High Reynolds ◽  
Flow Compressor

The results of a numerical investigation to predict the flow field including wakes and mixing in axial flow compressor rotors has been presented in this paper. The wake behaviour in a moderately loaded compressor rotor has been studied numerically using a three-dimensional incompressible Navier-Stokes solver with a high Reynolds number form of the k–ε turbulence model. The equations are solved using a time dependent implicit technique. The agreement between the measured data and the predictions are good; including the blade boundary layer profiles, wake mean velocity profiles and decay. The ability of the pseudo-compressibility scheme to predict the entire flow field including the near and far wake profiles and its decay characteristics, effect of loading and the viscous losses of a three-dimensional rotor flow field has been demonstrated. An analysis of the passage averaged velocities and the pressure coefficients shows that the mixing in the downstream regions away from the hub and annulus walls is dominated by wake diffusion. In regions away from the walls, the radial mixing is predominantly caused by the transport of mass, momentum and energy by the radial component of velocity in the wake.

Numerical Prediction of Wakes in Cascades and Compressor Rotors Including the Effects of Mixing: Part II—Rotor Passage Flow and Wakes Including the Effects of Spanwise Mixing

1992 ◽  
Vol 114 (3) ◽  
pp. 617-626 ◽  
Author(s):  
N. Suryavamshi ◽  
B. Lakshminarayana
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Axial Flow ◽  
Radial Component ◽  
Navier Stokes ◽  
Mean Velocity ◽  
Compressor Rotor ◽  
Entire Flow ◽  
High Reynolds ◽  
Flow Compressor

The results of a numerical investigation to predict the flow field including wakes and mixing in axial flow compressor rotors has been presented in this paper. The wake behavior in a moderately loaded compressor rotor has been studied numerically using a three-dimensional incompressible Navier–Stokes solver with a high Reynolds number form of the k–ε turbulence model. The equations are solved using a time-dependent implicit technique. The agreement between the measured data and the predictions is good, including the blade boundary layer profiles, wake mean velocity profiles, and decay. The ability of the pseudocompressibility scheme to predict the entire flow field including the near and far wake profiles and its decay characteristics, effect of loading, and the viscous losses of a three-dimensional rotor flow field has been demonstrated. An analysis of the passage-averaged velocities and the pressure coefficients shows that the mixing in the downstream regions away from the hub and annulus walls is dominated by wake diffusion. In regions away from the walls, the radial mixing is predominantly caused by the transport of mass, momentum, and energy by the radial component of velocity in the wake.

scholarly journals Experimental Investigations of Airfoil- and Endwall Boundary Layers in a Subsonic Compressor Stage

1986 ◽  
Author(s):  
H. E. Gallus ◽  
H. Hoenen
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Boundary Layers ◽  
Three Dimensional ◽  
Axial Flow ◽  
Experimental Investigations ◽  
Turbulence Energy ◽  
Compressor Stage ◽  
Stator Blade ◽  
Flow Compressor

Criteria for the maximum diffusion allowable in a blade row without reaching stall play an important part in the design of highly loaded axial-flow compressors. Most of these criteria for maximum blade loading were derived from wind tunnel measurements of 2-d-steady cascade flow. As the flow field in turbomachines is extremely unsteady and of three-dimensional nature the boundary layers are influenced by these effects. The paper deals with the results of boundary layer measurements in a stator blade channel of a subsonic axial-flow compressor stage at various operating points between unthrottled and highly throttled flow (near stall). In front of the stator, the time-averaged velocity profiles as well as the fluctuations due to the unsteady flow field downstream of the rotor were measured. The growing of the separation zones inside the channel with increased blade load is studied in detail. Photos of flow visualization in the boundary layers by dye-injection and flow patterns derived from hot-wire measurements illustrate the physics of boundary layer behavior and separation due to increasing stator blade load. The investigations include measurements of the turbulence energy and a frequency analysis of the velocity fluctuations in the boundary layers.

Phase-Locked Investigation of Secondary Flows Perturbed by Passing Wakes in a High-Lift LPT Turbine Cascade

2015 ◽  
Author(s):  
Daniele Infantino ◽  
Francesca Satta ◽  
Daniele Simoni ◽  
Marina Ubaldi ◽  
Pietro Zunino ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Experimental Investigations ◽  
Turbine Cascade ◽  
Ensemble Averaging ◽  
Tangential Plane ◽  
Mean Velocity ◽  
High Lift ◽  
Passage Vortex

The present work describes the experimental investigations carried out at the Aerodynamics and Turbomachinery Laboratory of Genoa University aimed at characterizing the unsteady features of the secondary flows in a High-Lift Low Pressure Turbine cascade perturbed by incoming wakes. The investigations have been carried out at the nominal exit flow Reynolds number of 300000 in a 5-blade large-scale linear cascade. Hot-wire phase-locked ensemble-averaging technique has been applied to analyze in depth the time-dependent velocity and turbulence intensity distributions in a downstream tangential plane during a wake period. A multiple rotation technique has been used in order to measure the three velocity components as well as the Reynolds stress tensor terms. Acquired data are presented in terms of the phase-dependent mean velocity, turbulence and vorticity maps in order to distinguish between the contributions due to incoming wake velocity defect and those due to the turbulence carried by wakes on the phase-dependent secondary flow structures. Results clearly highlight a significant distortion and weakening of the passage vortex when the upstream wake passes through the measuring domain. Also an evident displacement of the passage vortex position has been observed in the wake period. This analysis allows understanding the difference in the three dimensional time mean structures of the exit flow field between the steady and unsteady operations.

Mean and Turbulence Characteristics of a Class of Three-Dimensional Wall Jets—Part 1: Mean Flow Characteristics

1991 ◽  
Vol 113 (4) ◽  
pp. 620-628 ◽  
Author(s):  
G. Padmanabham ◽  
B. H. Lakshmana Gowda
Keyword(s):  
Three Dimensional ◽  
Flow Characteristics ◽  
Experimental Investigations ◽  
Wall Jet ◽  
Mean Flow ◽  
Wall Jets ◽  
Mean Velocity ◽  
Turbulence Characteristics ◽  
Turbulent Wall ◽  
And Behavior

This paper reports experimental investigations on mean and turbulence characteristics of three-dimensional, incompressible, isothermal turbulent wall jets generated from orifices having the shapes of various segments of a circle. In Part 1, the mean flow characteristics are presented. The turbulence characteristics are presented in Part 2. The influence of the geometry on the characteristic decay region of the wall jet is brought out and the differences with other shapes are discussed. Mean velocity profiles both in the longitudinal and lateral planes are measured and compared with some of the theoretical profiles. Wall jet expansion rates and behavior of skin-friction are discussed. The influence of the geometry of the orifice on the various wall jet properties is presented and discussed. Particularly the differences between this class of geometry and rectangular geometries are critically discussed.

A three-dimensional wake model for low earth orbit

1983 ◽  
Author(s):  
I. KATZ ◽  
D. COOKE ◽  
D. PARKS ◽  
M. MANDELL ◽  
A. RUBIN
Keyword(s):  
Three Dimensional ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Wake Model

EXPERIMENTAL INVESTIGATION OF FLOW RESPONSE TO STATIONARY DISTURBANCE IN ROTATING-DISK FLOW

2019 ◽  
Vol XVI (2) ◽  
pp. 13-22
Author(s):  
Muhammad Ehtisham Siddiqui
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Flow ◽  
Three Dimensional ◽  
Rotating Disk ◽  
Careful Analysis ◽  
Laboratory Frame ◽  
Transition To Turbulence ◽  
Turbulent Regime ◽  
Mean Velocity ◽  
Layer Flow

Three-dimensional boundary-layer flow is well known for its abrupt and sharp transition from laminar to turbulent regime. The presented study is a first attempt to achieve the target of delaying the natural transition to turbulence. The behaviour of two different shaped and sized stationary disturbances (in the laboratory frame) on the rotating-disk boundary layer flow is investigated. These disturbances are placed at dimensionless radial location (Rf = 340) which lies within the convectively unstable zone over a rotating-disk. Mean velocity profiles were measured using constant-temperature hot-wire anemometry. By careful analysis of experimental data, the instability of these disturbance wakes and its estimated orientation within the boundary-layer were investigated.

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