An axisymmetric ‘fluidic’ nozzle to generate jet precession

1998 ◽  
Vol 370 ◽  
pp. 347-380 ◽  
Author(s):  
G. J. NATHAN ◽  
S. J. HILL ◽  
R. E. LUXTON
Keyword(s):  
Flow Visualization ◽  
Large Scale ◽  
Three Dimensional ◽  
Fast Response ◽  
Surface Flow ◽  
Sudden Expansion ◽  
Pressure Transducers ◽  
Acoustic Coupling ◽  
Response Pressure ◽  
Surface Flow Visualization

A continuously unstable precessing flow within a short cylindrical chamber following a large sudden expansion is described. The investigation relates to a nozzle designed to produce a jet which achieves large-scale mixing in the downstream field. The inlet flow in the plane of the sudden expansion is well defined and free from asymmetry. Qualitative flow visualization in water and semi-quantitative surface flow visualization in air are reported which identify this precession within the chamber. Quantitative simultaneous measurements from fast-response pressure transducers at four tapping points on the internal walls of the nozzle chamber confirm the presence of the precessing field. The investigation focuses on the flow within the nozzle chamber rather than that in the emerging jet, although the emerging flow is also visualized.Two flow modes are identified: a ‘precessing jet’ mode which is instantaneously highly asymmetric, and a quasi-symmetric ‘axial jet’ mode. The precessing jet mode, on which the investigation concentrates, predominates in the geometric configuration investigated here. A topologically consistent flow field, derived from the visualization and from the fluctuating pressure data, which describes a three-dimensional and time-dependent precessing motion of the jet within the chamber is proposed. The surface flow visualization quantifies the axial distances to lines of positive and negative bifurcation allowing comparison with related flows involving large-scale precession or flapping reported by others. The Strouhal numbers (dimensionless frequencies) of these flows are shown to be two orders of magnitude lower than that measured in the shear layer of the jet entering the chamber. The phenomenon is demonstrated to be unrelated to acoustic coupling.

The Effect of Vane Clocking on the Unsteady Flowfield in a One and a Half Stage Transonic Turbine

2007 ◽  
Author(s):  
O. Schennach ◽  
R. Pecnik ◽  
B. Paradiso ◽  
E. Go¨ttlich ◽  
A. Marn ◽  
...  
Keyword(s):  
Laser Doppler Velocimetry ◽  
Three Dimensional ◽  
Fast Response ◽  
Navier Stokes ◽  
Doppler Velocimetry ◽  
Pressure Transducers ◽  
Wake Interactions ◽  
Transonic Turbine ◽  
Response Pressure ◽  
Vane Clocking

The current paper presents the results of numerical and experimental clocking investigations performed in a high-pressure transonic turbine with a downstream vane row. The objective was a detailed analysis of shock and wake interactions in such a 1.5 stage machine while clocking the vanes. Therefore a transient 3D-Navier Stokes calculation was done for two clocking positions and the three dimensional results are compared with Laser-Doppler-Velocimetry measurements at midspan. Additionally the second vane was equipped with fast response pressure transducers to record the instantaneous surface pressure for 20 different clocking positions at midspan.

An Experimental Investigation of the Flow Through an Axial-Flow Pump

1995 ◽  
Vol 117 (3) ◽  
pp. 485-490 ◽  
Author(s):  
W. C. Zierke ◽  
W. A. Straka ◽  
P. D. Taylor
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Axial Flow ◽  
Fast Response ◽  
Complex Flow ◽  
Penn State ◽  
Response Pressure ◽  
Axial Flow Pump ◽  
Scale Experiment ◽  
High Reynolds

The high Reynolds number pump (HIREP) facility at ARL Penn State has been used to perform a low-speed, large-scale experiment of the incompressible flow of water through a two-blade-row turbomachine. The objectives of this experiment were to provide a database for comparison with three-dimensional, turbulent flow computations, to evaluate engineering models, and to improve our physical understanding of many of the phenomena involved in this complex flow field. This summary paper briefly describes the experimental facility, as well as the experimental techniques—such as flow visualization, static-pressure measurements, laser Doppler velocimetry, and both slow- and fast-response pressure probes. Then, proceeding from the inlet to the exit of the pump, the paper presents highlights of experimental measurements and data analysis, giving examples of measured physical phenomena such as endwall boundary layers, separation regions, wakes, and secondary vortical structures. In conclusion, this paper provides a synopsis of a well-controlled, larger scope experiment that should prove helpful to those who wish to use the database.

Centrifugal Compressor Impeller Aerodynamics: An Experimental Investigation

1990 ◽  
Author(s):  
H. David Joslyn ◽  
Joost J. Brasz ◽  
Robert P. Dring
Keyword(s):  
Flow Visualization ◽  
Centrifugal Compressor ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Companion Paper ◽  
Surface Flow ◽  
Navier Stokes ◽  
Pressure Distributions ◽  
Compressor Impeller ◽  
Surface Flow Visualization

The ability to acquire blade loadings (surface pressure distributions) and surface flow visualization on an unshrouded centrifugal compressor impeller is demonstrated. Circumferential and streamwise static pressure distributions acquired on the stationary shroud are also presented. Data was acquired in a new facility designed for centrifugal compressor aerodynamic research. Blade loadings calculated with a blade–to–blade potential flow analysis are compared with the measured results. Surface flow visualization reveals some complex aspects of the flow on the surface of the impeller blading and hub. In a companion paper, Dorney and Davis (1990), a state–of–the–art, three–dimensional, time–accurate, Navier Stokes prediction of the flow through the impeller is presented.

Unsteady Velocity- and Turbulence Measurements With a Fast Response Pressure Probe

1990 ◽  
Author(s):  
G. Ruck ◽  
H. Stetter
Keyword(s):  
Dynamic Behaviour ◽  
Three Dimensional ◽  
Mechanical Damage ◽  
Axial Compressor ◽  
Fast Response ◽  
Pressure Probe ◽  
Pressure Transducers ◽  
Rotating Blade ◽  
Response Pressure ◽  
Probe Head

To investigate the three-dimensional unsteady flow and the turbulence intensities behind rotating blade rows of turbomachines, a procedure using a fast-response pressure probe has been developed. The integration of the cylindrical miniature pressure transducers into the probe head minimizes the risk of mechanical damage. The dynamic behaviour of the probe was analyzed. The application of the probe to the rotor exit flow of an axial compressor is described and results are presented.

The Effect of Vane Clocking on the Unsteady Flow Field in a One-and-a-Half Stage Transonic Turbine

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
O. Schennach ◽  
R. Pecnik ◽  
B. Paradiso ◽  
E. Göttlich ◽  
A. Marn ◽  
...  
Keyword(s):  
Laser Doppler Velocimetry ◽  
Three Dimensional ◽  
Fast Response ◽  
Navier Stokes ◽  
Doppler Velocimetry ◽  
Pressure Transducers ◽  
Wake Interactions ◽  
Transonic Turbine ◽  
Response Pressure ◽  
Vane Clocking

The current paper presents the results of numerical and experimental clocking investigations performed in a high-pressure transonic turbine with a downstream vane row. The objective was a detailed analysis of shock and wake interactions in such a 1.5-stage machine while clocking the vanes. Therefore, a transient 3D Navier–Stokes calculation was done for two clocking positions, and the three-dimensional results are compared with laser-Doppler-velocimetry measurements at midspan. Additionally, the second vane was equipped with fast response pressure transducers to record the instantaneous surface pressure for 20 different clocking positions at midspan.

Measurements of turbulent crossflow separation created by a curved body of revolution

2007 ◽  
Vol 589 ◽  
pp. 353-374 ◽  
Author(s):  
P. A. GREGORY ◽  
P. N. JOUBERT ◽  
M. S. CHONG
Keyword(s):  
Flow Visualization ◽  
Skin Friction ◽  
Cross Sections ◽  
Separated Flow ◽  
Surface Flow ◽  
The Body ◽  
Body Of Revolution ◽  
Outer Flow ◽  
Friction Measurements ◽  
Surface Flow Visualization

Using the method pioneered by Gurzhienko (1934), the crossflow separation produced by a body of revolution in a steady turn is examined using a stationary deformed body placed in a wind tunnel. The body of revolution was deformed about a radius equal to three times the body's length. Surface pressure and skin-friction measurements revealed regions of separated flow occurring over the rear of the model. Extensive surface flow visualization showed the presence of separated flow bounded by a separation and reattachment line. This region of separated flow began just beyond the midpoint of the length of the body, which was consistent with the skin-friction data. Extensive turbulence measurements were performed at four cross-sections through the wake including two stations located beyond the length of the model. These measurements revealed the location of the off-body vortex, the levels of turbulent kinetic energy within the shear layer producing the off-body vorticity and the large values of 〈uw〉 stress within the wake. Velocity spectra measurements taken at several points in the wake show evidence of the inertial sublayer. Finally, surface flow topologies and outer-flow topologies are suggested based on the results of the surface flow visualization.

The Effect of the Operating Point on the Pressure Fluctuations at the Blade Passage Frequency in the Volute of a Centrifugal Pump

2002 ◽  
Vol 124 (3) ◽  
pp. 784-790 ◽  
Author(s):  
Jorge L. Parrondo-Gayo ◽  
Jose´ Gonza´lez-Pe´rez ◽  
Joaquı´n Ferna´ndez-Francos
Keyword(s):  
Centrifugal Pump ◽  
Pressure Fluctuations ◽  
Fast Response ◽  
Strong Increase ◽  
Flow Rates ◽  
Blade Passage ◽  
Pressure Transducers ◽  
Leading Role ◽  
Dynamic Forces ◽  
Response Pressure

An experimental investigation is presented which analyzes the unsteady pressure distribution existing in the volute of a conventional centrifugal pump with a nondimensional specific speed of 0.48, for flow-rates from 0% to 160% of the best-efficiency point. For that purpose, pressure signals were obtained at 36 different locations along the volute casing by means of fast-response pressure transducers. Particular attention was paid to the pressure fluctuations at the blade passage frequency, regarding both amplitude and phase delay relative to the motion of the blades. Also, the experimental data obtained was used to adjust the parameters of a simple acoustic model for the volute of the pump. The results clearly show the leading role played by the tongue in the impeller-volute interaction and the strong increase in the magnitude of dynamic forces and dipole-like sound generation in off-design conditions.

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