scholarly journals A Method of Predicting the Energy Losses in Vaneless Diffusers of Centrifugal Compressors

1989 ◽  
Author(s):  
Huashu Dou
Keyword(s):  
Experimental Data ◽  
Energy Loss ◽  
Total Energy ◽  
Wall Friction ◽  
Energy Losses ◽  
Flow Conditions ◽  
Centrifugal Compressors ◽  
Flow Losses ◽  
Vaneless Diffusers ◽  
Good Agreement

The flow losses in the veneless diffusers of centrifugal compressors is investigated. It is found that the total energy loss in vaneless diffusers is a function of Bsin2 α0 when inlet flow conditions and radius ratio between inlet and outlet are given. A wall friction coefficient equation is derived and a method of predicting the total energy loss excepting mixing loss is presented. A comparison is made between results obtained from this method and experimental data generated by the author as well as data from the literature. Good agreement is obtained.

On the Comparison Between Lubrication Theory, Including Turbulence and Inertia Forces, and Some Existing Experimental Data

1975 ◽  
Vol 97 (3) ◽  
pp. 439-448 ◽  
Author(s):  
V. N. Constantinescu ◽  
S. Galetuse ◽  
F. Kennedy
Keyword(s):  
Experimental Data ◽  
Thin Films ◽  
Reynolds Numbers ◽  
Lubrication Theory ◽  
Incoming Flow ◽  
Flow Conditions ◽  
Film Rupture ◽  
Inertia Forces ◽  
Proper Consideration ◽  
Good Agreement

The results obtained by using lubrication theory, including inertia forces, are checked against experimental data concerning flows in relatively thin films at moderate and large Reynolds numbers. It is shown that a reasonably good agreement is obtained provided that the peculiar features of the experimental flow are properly taken into account; namely, proper consideration of the type of flow (laminar, transition, turbulent), proper evaluation of the region where lubrication flow prevails, entrance flow conditions (relating the flow into the film to the incoming flow), conditions for film rupture, cavitation or separation.

Grain Flow for Rough Surfaces Considering Grain/Grain Collision Elasticity

2005 ◽  
Vol 127 (4) ◽  
pp. 837-844 ◽  
Author(s):  
Yeau-Ren Jeng ◽  
Hung-Jung Tsai
Keyword(s):  
Experimental Data ◽  
Grain Size ◽  
Energy Loss ◽  
Collision Energy ◽  
Surface Characteristics ◽  
Roughness Effects ◽  
Lubrication Equation ◽  
Grain Flow ◽  
Mathematical Formulas ◽  
Good Agreement

Previous work by this group on an average lubrication equation for grain flow with roughness effects is extended to include grain-grain collision elasticity ranging from perfectly elastic to perfectly inelastic. The average lubrication equation is based on Haff’s grain flow theory, with flow factors from Patir and Cheng and Tripp’s use of perturbation. The derived flow factors are obtained as functions of rough surface characteristics, grain size, and collision pattern. As collision energy loss approaches zero, the inelastic results approach those for perfectly elastic grain collision. The mathematical formulas for flow factors, grain/grain collision elasticity, grain size, and roughness are presented and discussed. Predicitons for the elastic and inelastic cases are graphically demonstrated and compared. The derived average lubrication equation for grain flow shows good agreement with the theoretical and experimental data of Yu, Craig, and Tichy [J. Rheol., 38(4), 921 (1994)].

scholarly journals Investigation of the effects of main geometric parameters and flow characteristics on secondary flow losses in a turbine cascade

2021 ◽  
Vol 2131 (3) ◽  
pp. 032081
Author(s):  
M Mesbah ◽  
V G Gribin ◽  
K Souri
Keyword(s):  
Mach Number ◽  
Aspect Ratio ◽  
Total Energy ◽  
Flow Characteristics ◽  
Numerical Results ◽  
Energy Losses ◽  
Inlet Flow ◽  
Flow Angle ◽  
Flow Losses ◽  
Exit Mach Number

Abstract This paper presents numerical simulation results of a three-dimensional (3D) transitional flow in a stator cascade of an axial turbine. The influences of the main geometric parameters and flow characteristics including, the blade aspect ratio, pitch-to-chord ratio, inlet flow angle, and exit Mach number, on secondary flows development and end-wall losses, were studied. The numerical results were validated by the results of experiments conducted in the laboratory of the steam and gas turbine faculty of the Moscow Power Engineering Institute. The maximum difference between computed and experimental results was 2.4 %. The total energy losses decrease by 20 % when the exit Mach number changes from 0.38 to 0.8. Numerical results indicated that the blade aspect ratio had the most effect on secondary flow losses. The total energy losses increase by 46.6 % when the aspect ratio decreases from 1 to 0.25. The total loss of energy by 13.2 % decreases by increasing the inlet flow angle from 60 degrees to 90 degrees. Then by increasing the inlet flow angle from 90 to 110 degrees, the total loss rises by 3.6%. As the pitch-to-chord ratio increases from 0.7 to 0.75, the total energy losses are reduced by 12.2 %. Then by increasing the pitch-to-chord ratio from 0.75 to 0.8, the total energy losses increase by 6 %. As with experimental data, the numerical results showed that the optimal inlet flow angle and relative pitch for the cascade are 90 degrees and 0.75, respectively.

scholarly journals The Energy Loss Distributions of 1 MeV Electrons in Aluminium Foils

1955 ◽  
Vol 8 (1) ◽  
pp. 98 ◽  
Author(s):  
JA McDonell ◽  
MA Hanson ◽  
PR Wilson
Keyword(s):  
Energy Loss ◽  
Multiple Scattering ◽  
Energy Losses ◽  
Loss Distributions ◽  
Good Agreement

The energy loss distributions for 1 MeV electrons traversing aluminium foils of various thicknesses have been investigated experimentally. Several of the foils were of thicknesses such that the distributions were expected to show considerable effects due to multiple scattering. It was found that the most probable energy losses were in good agreement with those predicted by the calculations of Hebbard and Wilson (1955).

IONIZATION LOSS BY COSMIC-RAY MU-MESONS IN ARGON

1959 ◽  
Vol 37 (2) ◽  
pp. 189-202 ◽  
Author(s):  
Georges Hall
Keyword(s):  
Experimental Data ◽  
Energy Loss ◽  
Ionization Chamber ◽  
Cosmic Ray ◽  
Statistical Distribution ◽  
Experimental Curve ◽  
Energy Losses ◽  
Ionization Loss ◽  
Electron Collection ◽  
Probable Loss

The ionization of argon by cosmic-ray mu-mesons of minimum specific ionization has been studied by means of a calibrated pressure-ionization chamber using electron collection. Corrections which are shown to be necessary have been applied to the experimental data. The shape of the experimental curve of statistical distribution of energy loss agrees with the theoretically predicted shape, for energy losses greater than the most probable loss (300 kev).

Energy loss of protons passing through hydrogen

1955 ◽  
Vol 232 (1190) ◽  
pp. 423-434 ◽  
Keyword(s):  
Experimental Data ◽  
Energy Loss ◽  
Total Energy ◽  
Detailed Analysis ◽  
Cross Sections ◽  
Atomic Hydrogen ◽  
Heavy Particle ◽  
Stopping Power ◽  
Particle Collisions ◽  
Hydrogen Atoms

The cross-sections of processes involving protons and hydrogen atoms calculated by Bates, Dalgarno and Griffing using the Bom approximation are employed to make a detailed analysis of the contributions of excitation, ionization and capture to the stopping power of a gas of atomic hydrogen for a beam consisting initially of protons. A range of beam energies from 10 keV to 3 MeV is covered. The computed total energy loss is compared with experimental data and the accuracy of the Bom approximation for heavy particle collisions is discussed.

Losses in Vaneless Diffusers of Centrifugal Compressors and Pumps: Analysis, Experiment, and Design

1966 ◽  
Vol 88 (1) ◽  
pp. 49-60 ◽  
Author(s):  
J. P. Johnston ◽  
R. C. Dean
Keyword(s):  
Experimental Data ◽  
Centrifugal Compressor ◽  
Friction Loss ◽  
Sudden Expansion ◽  
Centrifugal Compressors ◽  
One Dimensional ◽  
Complex Theory ◽  
Loss Analysis ◽  
Analysis Experiment ◽  
Vaneless Diffusers

Two simple analyses are developed to predict losses in centrifugal compressor (or pump) vaneless diffusers: (a) One-dimensional, axisymmetric friction loss and (b) sudden-expansion mixing to account for losses in the diffuser caused by wakes of separated impeller blades. It is shown that these theories may be substituted for the more complex theory of Dean and Senoo [5]. Some experimental data are included to show the validity of the friction-loss analysis. Finally, the utility of the analyses in design is demonstrated.

REGRESSION ANALYSIS OF THE COEFFICIENTS OF VIBRATION ENERGY LOSSES IN GAS-DISCHARGE SYSTEMS OF POWER PLANTS

Akustika ◽  
2021 ◽  
pp. 115-118
Author(s):  
Aleksandr Chukarin ◽  
Alexey Fedenko ◽  
Aleksandr Shashurin ◽  
Viktoriia Vasilyeva
Keyword(s):  
Experimental Data ◽  
Regression Analysis ◽  
Standard Deviation ◽  
Energy Loss ◽  
Frequency Dependence ◽  
Power Plants ◽  
Vibration Energy ◽  
Energy Losses ◽  
Experimental Values ◽  
Approximate Result

Within the framework of this article, an experiment was conducted to determine the coefficient of energy loss of oscillatory motion. The analysis of the behavior of the frequency dependence of the coefficient showed that the approximation by a polynomial of degree 7 gives the most approximate result to the experimental values. The standard deviation of the experimental data from the polynomial is consistent with the error of the experimental data.

Investigation of the Prediction of Losses in Radial Vaneless Diffusers

1991 ◽  
Author(s):  
Huashu Dou
Keyword(s):  
Friction Loss ◽  
Wall Friction ◽  
Performance Parameters ◽  
Flow Angle ◽  
Flow Losses ◽  
Diffusion Loss ◽  
Small Width ◽  
Flow Loss ◽  
Vaneless Diffusers ◽  
The Stability

The non-dimensional width B and the inlet flow angle αi are the important parameters influencing the losses and the stability of radial vaneless diffusers. Their effects on diffuser losses are analyzed in this paper. The portions of the various flow losses change with the variation of non-dimensional width parameter B and flow angle αi. In a diffuser with small width B, the loss is primarily due to wall friction loss. In a diffuser with large B, the wall friction loss becomes a small part of the total loss, especially when αi is large. Comparison with experimental data shows that it is better to calculate the performance parameters of radial vaneless diffusers by using Dou’s method than by Senoo’s method in the design of centrifugal compressors. Senoo’s method is found to be only suitable for the conditions of small B values because it calculates simply the wall friction loss and the secondary flow loss and neglects diffusion loss.

Energy Levels and Electromagnetic Transition of 90-94mo Nuclei Using Ibm-1

2020 ◽  
pp. 149-152
Keyword(s):  
Experimental Data ◽  
Transition Probability ◽  
Energy Levels ◽  
Dynamical Symmetry ◽  
Interacting Boson Model ◽  
Excitation Energies ◽  
Electromagnetic Transition ◽  
Boson Model ◽  
Energy States ◽  
Good Agreement

The energy states for the J , b , ɤ bands and electromagnetic transitions B (E2) values for even – even molybdenum 90 – 94 Mo nuclei are calculated in the present work of "the interacting boson model (IBM-1)" . The parameters of the equation of IBM-1 Hamiltonian are determined which yield the best excellent suit the experimental energy states . The positive parity of energy states are obtained by using IBS1. for program for even 90 – 94 Mo isotopes with bosons number 5 , 4 and 5 respectively. The" reduced transition probability B(E2)" of these neuclei are calculated and compared with the experimental data . The ratio of the excitation energies of the 41+ to 21+ states ( R4/2) are also calculated . The calculated and experimental (R4/2) values showed that the 90 – 94 Mo nuclei have the vibrational dynamical symmetry U(5). Good agreement was found from comparison between the calculated energy states and electric quadruple probabilities B(E2) transition of the 90–94Mo isotopes with the experimental data .

Sign in / Sign up

Export Citation Format

Share Document