Influence of a Circumferential Exit Pressure Distortion on the Flow in an Impeller and Diffuser

1987 ◽  
Vol 109 (1) ◽  
pp. 48-54 ◽  
Author(s):  
M. Th. Sideris ◽  
R. A. Van den Braembussche
Keyword(s):  
Experimental Data ◽  
Static Pressure ◽  
Laser Doppler Anemometry ◽  
Theoretical Calculations ◽  
Interaction Model ◽  
Pressure Measurements ◽  
Velocity Measurements ◽  
Local Flow ◽  
Impeller Outlet ◽  
Theoretical Results

Detailed velocity measurements, using Laser Doppler Anemometry (LDA) and static pressure measurements in the vane/ess diffuser of a centrifugal compressor, are presented. They show the relation between the circumferential variation of the pressure and the local flow in the diffuser and at the impeller exit. Theoretical calculations using an impeller-diffuser interaction model have been made. A comparison between the theoretical results and experimental data allows an evaluation of the possibilities and shortcomings of such a calculation. It also illustrates the mechanisms by which the variation of the impeller outlet velocity is defined.

Validation of Surface Pressure Predictions for Nozzle Airfoil and Endwall Film Cooling Design Using Transonic Cascade Measurements

2013 ◽  
Author(s):  
Jason E. Dees ◽  
James A. Tallman ◽  
Michael A. Heminger ◽  
Daniel Wilde
Keyword(s):  
Surface Pressure ◽  
Film Cooling ◽  
Static Pressure ◽  
Experimental Studies ◽  
Tangential Direction ◽  
Maximum Deviation ◽  
Pressure Measurements ◽  
Local Flow ◽  
Cooling Design ◽  
Transonic Cascade

This study compares surface pressure measurements and predictions for a high pressure turbine first-stage nozzle vane. The surface pressure measurements were taken in a 3D annular cascade, consisting of four airfoils and five passages. The cascade was uncooled, axisymmetric at both inner and outer endwalls, and reproduced the design intent Reynolds and Mach numbers of the real engine component. Static pressure measurements were taken along the airfoil profile at 15, 50, and 85% span, with duplicate midspan measurements across the four airfoils for assessing the tangential periodicity of the flow. Static pressure measurements were also taken on the inner and outer endwall surfaces of the center airfoil passage, with 40 measurement points uniformly distributed over each endwall. Three methods of surface pressure prediction were compared with the data: (1) a 2D inviscid CFD solution of a single airfoil passage at fixed spanwise locations, (2) a 3D RANS CFD solution of a single airfoil passage, and (3) a 3D RANS CFD solution of the full five-passage cascade domain. Both of the single-passage solutions assumed flowfield periodicity in the tangential direction and compared favorably to the center passage airfoil data. This finding suggested that the cascade center passage was sufficiently representative of the full-annulus turbomachine environment and validated the cascade for further experimental studies. The adjacent airfoil pressure measurements quantified the passage-to-passage variation in the cascade flowfield, and the 3D full-cascade CFD compared favorably with the peripheral airfoil data. The full-cascade CFD also compared favorably with the data on both endwalls: with an average and maximum deviation of 0.5 and 2%, respectively. These findings provide confidence in the 3D CFD methods for use in determining local flow rates from cooling/leakage geometry, and serve as an important first step toward validating the methods for real-engine blockage effects like coolant and endwall contouring.

Velocity Measurements on the Forward Portion of a Cylinder

1990 ◽  
Vol 112 (2) ◽  
pp. 243-245 ◽  
Author(s):  
D. E. Paxson ◽  
R. E. Mayle
Keyword(s):  
Boundary Layer ◽  
Laminar Flow ◽  
Circular Cylinder ◽  
Vortex Shedding ◽  
Static Pressure ◽  
Free Stream ◽  
Stream Velocity ◽  
Pressure Measurements ◽  
Velocity Measurements ◽  
Flow Around A Cylinder

Velocity measurements in the laminar boundary layer around the forward portion of a circular cylinder are presented. These results are compared to Blasius’ theory for laminar flow around a cylinder using a free-stream velocity distribution obtained from static pressure measurements on the cylinder. Even though the flow is periodically unsteady as a result of vortex shedding from the cylinder, it is found that the agreement is excellent.

scholarly journals Collisions involving antiprotons and antihydrogen: an overview

2018 ◽  
Vol 376 (2116) ◽  
pp. 20170271 ◽  
Author(s):  
S. Jonsell
Keyword(s):  
Experimental Data ◽  
Theoretical Calculations ◽  
Research Project ◽  
Atoms And Molecules ◽  
Low Energies ◽  
Theoretical Results

I give an overview of experimental and theoretical results for antiproton and antihydrogen scattering with atoms and molecules (in particular H, He). At low energies ( 1 keV) there are practically no experimental data available. Instead I compare the results from different theoretical calculations, of various degrees of sophistication. At energies up to a few tens of eV, I focus on simple approximations that give reasonably accurate results, as these allow quick estimates of collision rates without embarking on a research project. This article is part of the Theo Murphy meeting issue ‘Antiproton physics in the ELENA era’.

Atomic Ionization Potentials Derived from Theoretical Calculations

1975 ◽  
Vol 53 (21) ◽  
pp. 2415-2420 ◽  
Author(s):  
Serafin Fraga ◽  
K. M. S. Saxena ◽  
Jacek Karwowski ◽  
Brian Bray
Keyword(s):  
Experimental Data ◽  
Predictive Value ◽  
Theoretical Calculations ◽  
Ground States ◽  
Theoretical Method ◽  
Ionization Potentials ◽  
Hartree Fock ◽  
Atomic Ionization ◽  
Total Energies ◽  
Theoretical Results

A table of all the ionization potentials of the elements lithium through krypton is presented.These values have been derived from the theoretical results obtained, within the Hartree–Fock method and including all the relativistic corrections, for the total energies of the ground states. The characteristics of the theoretical method are briefly outlined.Comparison with available experimental data establishes the excellent predictive value of the theoretical results.

scholarly journals The (K-, π+)Σ- - hypernuclear production in flight

2019 ◽  
Vol 3 ◽  
pp. 63
Author(s):  
Th. Petridou ◽  
C. Daskaloyannis
Keyword(s):  
Experimental Data ◽  
Interaction Model ◽  
Delta Function ◽  
Spin Orbit ◽  
Central Potential ◽  
Flight Data ◽  
Potential Depth ◽  
Square Well ◽  
Theoretical Results ◽  
Simple Interaction

The in-flight (K-,π+) Σ~-hypernuclear spectra are studied, using a simple interaction model with a square well central part and a delta function spin-orbit Σ-nuclearcore interaction. A comparison is made between the theoretical results and the in-flight (Α'~,π+) experimental data for 12Σ C, 16Σ Ο and 6Σ Li. A shallow potential, with a central potential depth of Vc = (-5 - il5)MeV and a spin-orbit depth of Vao = lbMeV, gives a satisfactory representation of the CERN and BNL in-flight data.

scholarly journals Mass spectra of one or two heavy quark mesons and diquarks within a nonrelativistic potential model

2021 ◽  
pp. 2150171
Author(s):  
L. X. Gutiérrez-Guerrero ◽  
Jesús Alfaro ◽  
A. Raya
Keyword(s):  
Experimental Data ◽  
Quantum Chromodynamics ◽  
Effective Potential ◽  
Mass Spectra ◽  
Potential Model ◽  
Theoretical Calculations ◽  
Interaction Model ◽  
Heavy Quarks ◽  
The Masses ◽  
Good Agreement

In this paper, the mass spectra of mesons with one or two heavy quarks and their diquarks partners are estimated within a nonrelativistic framework by solving Schrödinger equation with an effective potential inspired by a symmetry preserving Poincaré covariant vector–vector contact interaction model of quantum chromodynamics. Matrix Numerov method is implemented for this purpose. In our survey of mesons with heavy quarks, we fix the model parameter to the masses of groundstates and then extend our calculations for radial excitations and diquarks. The potential model used in this work gives results which are in good agreement with experimental data and other theoretical calculations.

Investigations Concerning Flow Patterns Within the Impeller Channels of Radial-Inflow Turbines, With Some Reference to the Influence of the Splitter Vanes

1967 ◽  
Vol 89 (4) ◽  
pp. 463-476 ◽  
Author(s):  
Ichiro Ariga ◽  
Ichiro Watanabe ◽  
Kunio Fujie
Keyword(s):  
Experimental Data ◽  
Relative Velocity ◽  
Static Pressure ◽  
Rotation Speed ◽  
Flow Patterns ◽  
Two Dimensional ◽  
Performance Parameters ◽  
Pressure Distributions ◽  
Theoretical Predictions ◽  
Theoretical Results

The experimental results of the relative velocity distributions together with the static pressure distributions within the impeller channels of radial-inflow turbines with and without splitter vanes are presented. The flow patterns within three stream surfaces (blade-to-blade surfaces) having different passage depths are shown using two performance parameters, i.e., nondimensional weight flow and nondimensional rotation speed. The impellers used were of purely radial type or of two-dimensional type. Further, theoretical predictions for the relative velocity distributions within the impeller channels having no splitter vanes were conducted, and comparisons of the theoretical results with experimental data were made.

MANUFACTURE INVESTIGATION OF CARTRIDGE WITH BOTTOM-MOST PART FLANGE BY DIRECT EXTRUSION WITH COUNTERPUNCH. REPORT 18. EXPERIMENTAL CHECK OF THEORETICAL RESULTS FOR DIFFERENT HOLLOW RADIUSES AND BOTTOM-MOST PART THICKNESSES

2020 ◽  
Vol 0 (9) ◽  
pp. 16-23
Author(s):  
A. L. Vorontsov ◽  
◽  
I. A. Nikiforov ◽  
Keyword(s):  
Strain Hardening ◽  
Theoretical Calculations ◽  
High Accuracy ◽  
Geometric Parameters ◽  
Strength Characteristics ◽  
Experimental Check ◽  
Hardening Material ◽  
Direct Extrusion ◽  
Theoretical Results

The results of an experimental check of the obtained theoretical formulae allowing us to determine the most important parameters of extrusion cartridges with a counterpunch for different hollow radiuses and bottom-most part thicknesses are presented. Characteristics of used tools, geometric parameters of extrusion experiments, strength characteristics of deformed materials and lubricants are described in detail. Both strain-hardening material and strain-unhardening material were studied. Methodology of the theoretical calculations is demonstrated in detail. High accuracy of the obtained design formulae was confirmed.

The Compliance of Solid, Wide-Faced Spur Gears

1990 ◽  
Vol 112 (4) ◽  
pp. 590-595 ◽  
Author(s):  
J. H. Steward
Keyword(s):  
Experimental Data ◽  
Contact Line ◽  
Load Distribution ◽  
3D Model ◽  
Spur Gear ◽  
Point Load ◽  
Spur Gears ◽  
Line Load ◽  
Gear Teeth ◽  
Theoretical Results

In this paper, the requirements for an accurate 3D model of the tooth contact-line load distribution in real spur gears are summarized. The theoretical results (obtained by F.E.M.) for the point load compliance of wide-faced spur gear teeth are set out. These values compare well with experimental data obtained from tests on a large spur gear (18 mm module, 18 teeth).

scholarly journals IV. On the dynamical theory of incompressible viscous fluids and the determination of the criterion

1895 ◽  
Vol 186 ◽  
pp. 123-164 ◽  
Keyword(s):  
Singular Solution ◽  
Physical State ◽  
Theoretical Calculations ◽  
Equations Of Motion ◽  
Dynamical Theory ◽  
Viscous Fluids ◽  
Linear Functions ◽  
Incompressible Viscous Fluids ◽  
Theoretical Results

1. The equations of motion of viscous fluid (obtained by grafting on certain terms to the abstract equations of the Eulerian form so as to adapt these equations to the case of fluids subject to stresses depending in some hypothetical manner on the rates of distortion, which equations Navier seems to have first introduced in 1822, and which were much studied by Cauchy and Poisson) were finally shown by St. Venant and Sir Gabriel Stokes, in 1845, to involve no other assumption than that the stresses, other than that of pressure uniform in all directions, are linear functions of the rates of distortion, with a co-efficient depending on the physical state of the fluid. By obtaining a singular solution of these equations as applied to the case of pendulums in steady periodic motion, Sir G. Stokes was able to compare the theoretical results with the numerous experiments that had been recorded, with the result that the theoretical calculations agreed so closely with the experimental determinations as seemingly to prove the truth of the assumption involved. This was also the result of comparing the flow of water through uniform tubes with the flow calculated from a singular solution of the equations so long as the tubes were small and the velocities slow. On the other hand, these results, both theoretical and practical, were directly at variance with common experience as to the resistance encountered by larger bodies moving with higher velocities through water, or by water moving with greater velocities through larger tubes. This discrepancy Sir G. Stokes considered as probably resulting from eddies which rendered the actual motion other than that to which the singular solution referred and not as disproving the assumption.

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