scholarly journals Lagrangian and Eulerian pressure field evaluation of rod-airfoil flow from time-resolved tomographic PIV

2010 ◽  
Vol 50 (4) ◽  
pp. 1057-1070 ◽  
Author(s):  
Daniele Violato ◽  
Peter Moore ◽  
Fulvio Scarano
Keyword(s):  
Pressure Field ◽  
Field Evaluation ◽  
Time Resolved ◽  
Tomographic Piv ◽  
Airfoil Flow

Investigation of the 3D Unsteady Rotor Pressure Field in a HP Turbine Stage

2002 ◽  
Author(s):  
E. Valenti ◽  
J. Halama ◽  
R. De´nos ◽  
T. Arts
Keyword(s):  
Reynolds Number ◽  
Mach Number ◽  
Pressure Field ◽  
Pressure Ratio ◽  
Turbine Stage ◽  
Time Resolved ◽  
Mach Number Distribution ◽  
Rotor Surface ◽  
Exit Mach Number ◽  
Unsteady Pressure Measurements

This paper presents steady and unsteady pressure measurements at three span locations (15, 50 and 85%) on the rotor surface of a transonic turbine stage. The data are compared with the results of a 3D unsteady Euler stage calculation. The overall agreement between the measurements and the prediction is satisfactory. The effects of pressure ratio and Reynolds number are discussed. The rotor time-averaged Mach number distribution is very sensitive to the pressure ratio of the stage since the incidence of the flow changes as well as the rotor exit Mach number. The time-resolved pressure field is dominated by the vane trailing edge shock waves. The incidence and intensity of the shock strongly varies from hub to tip due to the radial equilibrium of the flow at the vane exit. The decrease of the pressure ratio attenuates significantly the amplitude of the fluctuations. An increase of the pressure ratio has less significant effect since the change in the vane exit Mach number is small. The effect of the Reynolds number is weak for both the time-averaged and the time-resolved rotor static pressure at mid-span, while it causes an increase of the pressure amplitudes at the two other spans.

scholarly journals Time-resolved velocity and pressure field quantification in a flow-focusing device for ultrafast microbubble production

2021 ◽  
Vol 6 (11) ◽  
Author(s):  
Sarah Cleve ◽  
Christian Diddens ◽  
Tim Segers ◽  
Guillaume Lajoinie ◽  
Michel Versluis
Keyword(s):  
Pressure Field ◽  
Flow Focusing ◽  
Time Resolved

A Zone-Interaction Method for the Outer Flow Analysis of a Separated Airfoil

1980 ◽  
Vol 24 (02) ◽  
pp. 123-127
Author(s):  
James W. White
Keyword(s):  
Solution Method ◽  
Pressure Field ◽  
Flow Analysis ◽  
Separated Flow ◽  
Outer Flow ◽  
Free Streamlines ◽  
Principal Value ◽  
Airfoil Flow ◽  
Parallel Strips ◽  
Massive Separation

The pressure distribution over a subsonic airfoil experiencing massive separation is analyzed by a zonal modeling approach. Important physics are included in the mathematical description of each zone, and the zones are allowed to interact until convergence of the overall flow is obtained. The separated region is modeled as a zone of uniform pressure, the magnitude of which is determined by the solution method. The elliptic effect of the separated flow on the pressure field over the airfoil is included by bounding the stalled zone by two free streamlines which are iteratively located. Influence of the wake on the airfoil flow is modeled by two parallel strips which allow the subambient pressure in the stalled zone to adjust continuously black to freestream conditions. A Cauchy principal-value integral equation is used to compute the potential flow with no restrictions on the airfoil contour. Unlike most complex-variable methods, no mappings are required and the numerical solution is obtained entirely in the physical (Z) plane.

scholarly journals Decomposition of time-resolved tomographic PIV

2012 ◽  
Vol 52 (6) ◽  
pp. 1567-1579 ◽  
Author(s):  
Peter J. Schmid ◽  
Daniele Violato ◽  
Fulvio Scarano
Keyword(s):  
Time Resolved ◽  
Tomographic Piv

Influence of Rim Seal Purge Flow on the Performance of an Endwall-Profiled Axial Turbine

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
P. Schuepbach ◽  
R. S. Abhari ◽  
M. G. Rose ◽  
J. Gier
Keyword(s):  
Static Pressure ◽  
Pressure Field ◽  
Leading Edge ◽  
Streamwise Vortex ◽  
Suction Side ◽  
Total Efficiency ◽  
Time Resolved ◽  
Axial Turbine ◽  
Baseline Case ◽  
Purge Flow

Nonaxisymmetric endwall profiling is a promising method to reduce secondary losses in axial turbines. However, in high-pressure turbines, a small amount of air is ejected at the hub rim seal to prevent the ingestion of hot gases into the cavity between the stator and the rotor disk. This rim seal purge flow has a strong influence on the development of the hub secondary flow structures. This paper presents time-resolved experimental and computational data for a one-and-1/2-stage high work axial turbine, showing the influence of purge flow on the performance of two different nonaxisymmetric endwalls and the axisymmetric baseline case. The experimental total-to-total efficiency assessment reveals that the nonaxisymmetric endwalls lose some of their benefit relative to the baseline case when purge is increased. The first endwall design loses 50% of the efficiency improvement seen with low suction, while the second endwall design exhibits a 34% deterioration. The time-resolved computations show that the rotor dominates the static pressure field at the rim seal exit when purge flow is present. Therefore, the purge flow establishes itself as jets emerging at the blade suction side corner. The jet strength is modulated by the first vane pressure field. The jets introduce circumferential vorticity as they enter the annulus. As the injected fluid is turned around the rotor leading edge, a streamwise vortex component is created. The dominating leakage vortex has the same sense of rotation as the rotor hub passage vortex. The first endwall design causes the strongest circumferential variation in the rim seal exit static pressure field. Therefore, the jets are stronger with this geometry and introduce more vorticity than the other two cases. As a consequence the experimental data at the rotor exit shows the greatest unsteadiness within the rotor hub passage with the first endwall design.

scholarly journals 3D pressure field reconstruction from time-resolved stereoscopic PIV measurements by relaxation of Taylor's hypothesis

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Dominique Fratantonio ◽  
John James Charonko
Keyword(s):  
Pressure Field ◽  
National Laboratory ◽  
Reconstruction Algorithm ◽  
Turbulent Channel Flow ◽  
Reconstruction Method ◽  
Time Resolved ◽  
Material Derivative ◽  
Stereoscopic Piv ◽  
Air Jet ◽  
Taylor’S Hypothesis

This work presents reconstructions of 3D pressure fields starting from 2D3C stereoscopic-PIV (SPIV) measurements. In Fratantonio et al. (2021), we presented a new reconstruction algorithm, the “Instantaneous convection” method, capable of producing 3D velocity fields from time-resolved SPIV measurements. For reconstructions in flows with strong shear layers and high turbulence intensity, this method is able to provide time-resolved 3D velocity volumes that are more accurate than those that can be obtained from the more frequently employed reconstruction method based on the Taylor’s hypothesis and on the use of a mean convective field. Here we investigate the possibility of reconstructing the 3D pressure field from the timeresolved series of reconstructed 3D velocity data. A pseudo-tracking method is employed for computing the velocity material derivative, and the pressure field is then reconstructed by solving the 3D Poisson equation. The velocity and pressure reconstructions are validated on the Direct Numerical Simulation data of the turbulent channel flow taken from the John Hopkins Turbulence Database (JHTDB), and an application to experimental SPIV measurements of an air jet flow in coflow carried out at the Turbulent Mixing Tunnel (TMT) facility at Los Alamos National Laboratory is presented.

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