Averaging Methods for Determining the Performance of Large Fans from Field Measurements

1981 ◽  
Vol 103 (2) ◽  
pp. 345-347 ◽  
Author(s):  
P. M. Gerhart
Keyword(s):  
Pressure Rise ◽  
Field Measurements ◽  
Ideal Gas ◽  
Correction Factors ◽  
Flow Properties ◽  
State Equations ◽  
One Dimensional ◽  
Performance Variables ◽  
Definition Of ◽  
Velocity Pressure

When testing large fans in the field, it is often necessary to make measurements at locations where the distributions of gas velocity, pressure, and temperature are highly irregular. When this occurs the fan pressure rise or fan specific energy is usually expressed in terms of average values of pressure, density, and temperature. This paper proposes criteria for the definition of such averages and develops defining equations for them. The averages proposed allow the continuity, energy, and ideal gas state equations to be written in simple one-dimensional form without correction factors. Performance variables such as total pressure are defined in the customary way from the averages of the fundamental flow properties.

Sizing Safety Valve Vent Pipes for Saturated Steam

1982 ◽  
Vol 104 (1) ◽  
pp. 247-251
Author(s):  
H. E. Brandmaier
Keyword(s):  
Ideal Gas ◽  
Gas Analysis ◽  
Saturated Steam ◽  
Flow Conditions ◽  
Flow Properties ◽  
Pipe Length ◽  
One Dimensional ◽  
Choked Flow ◽  
Pipe Outlet ◽  
Orifice Valve

An earlier one-dimensional ideal gas analysis was changed to incorporate equilibrium properties of steam as given by the 1967 ASME steam tables. A generalized procedure based on pressure and entropy as independent variables is used to calculate choked flow conditions at the valve orifice, valve pipe outlet and vent pipe outlet. At the third location, the results are independent of whether flow in the vent pipe is supersonic or subsonic. An integral method is used to calculate the vent pipe length required to choke the flow. Computed data are compared with ideal gas data. The vent pipe size, to prevent blowback into the powerplant, is less conservative using real steam data. The flow properties, particularly specific volume, are significantly different.

scholarly journals Significance of Slippage and Electric Field in Mucociliary Transport of Biomagnetic Fluid

Lubricants ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 48
Author(s):  
Sufian Munawar
Keyword(s):  
Shear Stress ◽  
Flow Direction ◽  
Pressure Rise ◽  
Physical Parameters ◽  
Slippage Effect ◽  
Channel Surface ◽  
Electro Osmosis ◽  
Biomagnetic Fluid ◽  
Velocity Pressure ◽  
Metachronal Waves

Shear stress at the cilia wall is considered as an imperative factor that affects the efficiency of cilia beatings as it describes the momentum transfer between the fluid and the cilia. We consider a visco-inelastic Prandtl fluid in a ciliated channel under electro-osmotic pumping and the slippage effect at cilia surface. Cilia beating is responsible for the stimulation of the flow in the channel. Evenly distributed cilia tend to move in a coordinated rhythm to mobilize propulsive metachronal waves along the channel surface by achieving elliptic trajectory movements in the flow direction. After using lubrication approximations, the governing equations are solved by the perturbation method. The pressure rise per metachronal wavelength is obtained by numerically integrating the expression. The effects of the physical parameters of interest on various flow quantities, such as velocity, pressure gradient, pressure rise, stream function, and shear stress at the ciliated wall, are discussed through graphs. The analysis reveals that the axial velocity is enhanced by escalating the Helmholtz–Smoluchowski velocity and the electro-osmosis effects near the elastic wall. The shear stress at the ciliated boundary elevates with an increase in the cilia length and the eccentricity of the cilia structure.

The combined effect of lattice’s uniaxial strains and electron–phonon interaction’s screening on TBEC of the intersite bipolarons

2016 ◽  
Vol 30 (26) ◽  
pp. 1650186
Author(s):  
B. Yavidov ◽  
SH. Djumanov ◽  
T. Saparbaev ◽  
O. Ganiyev ◽  
S. Zholdassova ◽  
...  
Keyword(s):  
Ideal Gas ◽  
Einstein Condensation ◽  
Chain Model ◽  
One Dimensional ◽  
Electron Phonon Interaction ◽  
Model Lattice ◽  
Experimental Values ◽  
Bose Einstein ◽  
Derivatives Of ◽  
The Ideal

Having accepted a more generalized form for density-displacement type electron–phonon interaction (EPI) force we studied the simultaneous effect of uniaxial strains and EPI’s screening on the temperature of Bose–Einstein condensation [Formula: see text] of the ideal gas of intersite bipolarons. [Formula: see text] of the ideal gas of intersite bipolarons is calculated as a function of both strain and screening radius for a one-dimensional chain model of cuprates within the framework of Extended Holstein–Hubbard model. It is shown that the chain model lattice comprises the essential features of cuprates regarding of strain and screening effects on transition temperature [Formula: see text] of superconductivity. The obtained values of strain derivatives of [Formula: see text] [Formula: see text] are in qualitative agreement with the experimental values of [Formula: see text] [Formula: see text] of La[Formula: see text]Sr[Formula: see text]CuO4 under moderate screening regimes.

scholarly journals Introduction of an Universal Scale-Up Method for the Efficiency of Axial and Centrifugal Fans

2014 ◽  
Author(s):  
Peter F. Pelz ◽  
Stefan S. Stonjek
Keyword(s):  
Test Data ◽  
Scale Up ◽  
Pressure Rise ◽  
Flow Coefficient ◽  
Total Efficiency ◽  
Scaling Method ◽  
Centrifugal Fans ◽  
Axial Fans ◽  
Definition Of ◽  
Acceptance Tests

Acceptance tests on large fans to prove the performance (efficiency and total pressure rise) to the customer are expensive and sometimes even impossible to perform. Hence there is a need for the manufacturer to reliably predict the performance of fans from measurements on down-scaled test fans. The commonly used scale-up formulas give satisfactorily results only near the design point, where inertia losses are small in comparison to frictional losses. At part- and overload the inertia losses are dominant and the scale-up formulas used so far fail. In 2013 Pelz and Stonjek introduced a new scaling method which fullfills the demands ( [1], [2]). This method considers the influence of surface roughness and geometric variations on the performance. It consists basically of two steps: Initially, the efficiency is scaled. Efficiency scaling is derived analytically from the definition of the total efficiency. With the total derivative it can be shown that the change of friction coefficient is inversely proportional to the change of efficiency of a fan. The second step is shifting the performance characteristic to a higher value of flow coefficient. It is the task of this work to improve the scaling method which was previously introduced by Pelz and Stonjek by treating the rotor/impeller and volute/stator separately. The validation of the improved scale-up method is performed with test data from two axial fans with a diameter of 1000 mm/250mm and three centrifugal fans with 2240mm/896mm/224mm diameter. The predicted performance characteristics show a good agreement to test data.

A Study of a Sharp 90 Degree Curved Flow

1992 ◽  
Author(s):  
R. H. Kim
Keyword(s):  
Turbulence Model ◽  
Ideal Gas ◽  
Radius Of Curvature ◽  
Dimensional Theory ◽  
One Dimensional ◽  
Algebraic Stress Model ◽  
Finite Difference Technique ◽  
Curved Tube ◽  
Kinetic Energy Loss ◽  
The Ideal

Abstract An investigation of air flow along a 90 degree elbow-like tube is conducted to determine the velocity and temperature distributions of the flow. The tube has a sharp 90 degree turn with a radius of curvature of almost zero. The flow is assumed to be a steady two-dimensional turbulent flow satisfying the ideal gas relation. The flow will be analyzed using a finite difference technique with the K-ε turbulence model, and the algebraic stress model (ASM). The FLUENT code was used to determine the parameter distributions in the passage. There are certain conditions for which the K-ε model does not describe the fluid phenomenon properly. For these conditions, an alternative turbulence model, the ASM with or without QUICK was employed. FLUENT has these models among its features. The results are compared with the result computed by using elementary one-dimensional theory including the kinetic energy loss along the passage of the sharp 90 degree curved tube.

Magneto-thermo hydrodynamic peristaltic flow of Eyring-Powell nanofluid in asymmetric channel

2018 ◽  
Vol 7 (2) ◽  
pp. 83-90 ◽  
Author(s):  
Saima Noreen
Keyword(s):  
Pressure Rise ◽  
Peristaltic Flow ◽  
Asymmetric Channel ◽  
Convective Boundary Conditions ◽  
Convective Boundary ◽  
Long Wavelength ◽  
Basic Equations ◽  
Velocity Pressure ◽  
Biot Numbers ◽  
Parameters Of Interest

Abstract This research is devoted to the peristaltic flow of Eyring-Powell nanofluid in an asymmetric channel. Robins-type (convective) boundary conditions are employed in the presence of mixed convection and magnetic field. The basic equations of Eyring-Powell nanofluid are modeled in wave frame of reference. Long wavelength and low Reynolds number approach is utilized. Numerical solution of the governing problem is computed and analyzed. The effects of various parameters of interest on the velocity, pressure rise, concentration and temperature are discussed and illustrated graphically. Brownian motion parameter and thermophoresis parameter facilitates the increase in temperature of fluid. Biot numbers serve to reduce the temperature at channel walls.

Assessment of Certainty of Ventilation Processes Mathematical Modeling

2015 ◽  
Vol 725-726 ◽  
pp. 1255-1260
Author(s):  
Tamara Daciuk ◽  
Vera Ulyasheva
Keyword(s):  
Mathematical Modeling ◽  
Turbulent Flows ◽  
Turbulence Models ◽  
Field Measurements ◽  
Heat Emission ◽  
Emission Sources ◽  
Wide Range ◽  
Calculation Results ◽  
Definition Of ◽  
Semiempirical Models

Numerical experiment has been successfully used during recent 10-15 years to solve a wide range of thermal and hydrogasodynamic tasks. Application of mathematical modeling used to design the ventilation systems for production premises characterized by heat emission may be considered to be an effective method to obtain reasonable solutions. Results of calculation performed with numerical solution of ventilation tasks depend on turbulence model selection. Currently a large number of different turbulence models used to calculate turbulent flows are known. Testing and definition of applicability limits for semiempirical models of turbulence should be considered to be a preliminary stage of calculation. This article presents results of test calculations pertaining to thermal air process modeling in premises characterized by presence of heat emission sources performed with employment of different models of turbulence. Besides, analysis of calculation results and comparison with field measurements data are presented.

Influence of an inclined magnetic field on heat and mass transfer of the peristaltic flow of a couple stress fluid in an inclined channel

2017 ◽  
Vol 14 (1) ◽  
pp. 7-18 ◽  
Author(s):  
Ajaz Ahmad Dar ◽  
K. Elangovan
Keyword(s):  
Magnetic Field ◽  
Mass Transfer ◽  
Pressure Gradient ◽  
Couple Stress ◽  
Pressure Rise ◽  
Peristaltic Flow ◽  
Inclined Magnetic Field ◽  
Content Type ◽  
Inclined Channel ◽  
Velocity Pressure

Purpose This paper aims to intend for investigating the influence of an inclined magnetic field on the peristaltic flow of a couple stress fluid through an inclined channel with heat and mass transfer. Design/methodology/approach Long wavelength and low Reynolds number methodology is actualized for simplifying the highly nonlinear equations. Mathematical expressions of axial velocity, pressure gradient and volume flow rate are obtained. Pressure rise, frictional force and pumping phenomenon are portrayed and symbolized graphically. Exact and numerical solutions have been carried out. The computed results are presented graphically for various embedded parameters. Temperature and concentration profile are also scrutinized and sketched. Findings Results from the current study concluded that the fluid motion can be enhanced by increasing the inclination of both the magnetic field and the channel. Originality/value The elemental characteristics of this analysis is a complete interpretation of the influence of couple stress parameter and inclination of magnetic field on the velocity, pressure gradient, pressure rise and frictional forces.

Statistical mechanics of one-dimensional solitary-wave-bearing scalar fields: Exact results and ideal-gas phenomenology

1980 ◽  
Vol 22 (2) ◽  
pp. 477-496 ◽  
Author(s):  
J. F. Currie ◽  
J. A. Krumhansl ◽  
A. R. Bishop ◽  
S. E. Trullinger
Keyword(s):  
Solitary Wave ◽  
Statistical Mechanics ◽  
Scalar Fields ◽  
Ideal Gas ◽  
Exact Results ◽  
One Dimensional

Mathematical Analysis for Off-Design Performance of Cryogenic Turboexpander

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Subrata K. Ghosh ◽  
R. K. Sahoo ◽  
Sunil K. Sarangi
Keyword(s):  
Pressure Ratio ◽  
Expansion Ratio ◽  
Flow Conditions ◽  
Flow Properties ◽  
Dimensional Solution ◽  
One Dimensional ◽  
Design Performance ◽  
Fluid Properties ◽  
The Mean ◽  
Inlet Conditions

A study has been conducted to determine the off-design performance of cryogenic turboexpander. A theoretical model to predict the losses in the components of the turboexpander along the fluid flow path has been developed. The model uses a one-dimensional solution of flow conditions through the turbine along the mean streamline. In this analysis, the changes of fluid and flow properties between different components of turboexpander have been considered. Overall, turbine geometry, pressure ratio, and mass flow rate are input information. The output includes performance and velocity diagram parameters for any number of given speeds over a range of turbine pressure ratio. The procedure allows any arbitrary combination of fluid species, inlet conditions, and expansion ratio since the fluid properties are properly taken care of in the relevant equations. The computational process is illustrated with an example.

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