Fluid-Induced Rotordynamic Instability in Rotary Atomizers

1989 ◽  
Vol 111 (2) ◽  
pp. 318-324
Author(s):  
J. Colding-Jorgensen
Keyword(s):  
Fluid Flow ◽  
Flow Rate ◽  
High Speed ◽  
Test Stand ◽  
Design Parameters ◽  
Rotordynamic Coefficients ◽  
Fluid Properties ◽  
Flow Through

A theory is presented for the calculation of rotordynamic coefficients for the fluid-rotor interaction in rotary atomizers, based on calculation of the fluid flow through a whirling atomizer wheel. The theory predicts potentially unstable rotor whirl in high-speed rotary atomizers. The whirl frequency can be that of the first critical forward or the first critical backward precession of the rotor, depending on atomizer wheel geometry, speed, fluid properties, and flow rate. The predicted whirl phenomena have been produced in an atomizer test stand. Both forward and backward precession have been observed to become unstable. The observed whirl directions and amplitudes are consistent with the calculated coefficients. Some design parameters are identified that can help control and suppress the whirl.

Study of fluid flow through a channel deformed by piezoelement

2018 ◽  
Vol 13 (3) ◽  
pp. 1-10 ◽  
Author(s):  
I.Sh. Nasibullayev ◽  
E.Sh Nasibullaeva ◽  
O.V. Darintsev
Keyword(s):  
Fluid Flow ◽  
Pressure Drop ◽  
Boundary Conditions ◽  
Flow Rate ◽  
Contact Surface ◽  
Piezoelectric Element ◽  
Neumann Boundary ◽  
Differential Pressure ◽  
Physical Parameters ◽  
Flow Through

The flow of a liquid through a tube deformed by a piezoelectric cell under a harmonic law is studied in this paper. Linear deformations are compared for the Dirichlet and Neumann boundary conditions on the contact surface of the tube and piezoelectric element. The flow of fluid through a deformed channel for two flow regimes is investigated: in a tube with one closed end due to deformation of the tube; for a tube with two open ends due to deformation of the tube and the differential pressure applied to the channel. The flow rate of the liquid is calculated as a function of the frequency of the deformations, the pressure drop and the physical parameters of the liquid.

scholarly journals The Importance of Nanoparticles Addition in a Base Fluid Flow through a Porous Medium

2013 ◽  
Vol 8-9 ◽  
pp. 225-234
Author(s):  
Dalia Sabina Cimpean
Keyword(s):  
Porous Medium ◽  
Fluid Flow ◽  
Boundary Conditions ◽  
Mixed Convection ◽  
Mathematical Models ◽  
Base Fluid ◽  
Porous Matrix ◽  
Fluid Properties ◽  
Flow Through ◽  
Energy Equations

The present study is focused on the mixed convection fluid flow through a porous medium, when a different amount of nanoparticles is added in the base fluid. The nanofluid saturates the porous matrix and different situations of the flow between two walls are presented and discussed. Alternatively mathematical models are presented and discussed. A solution of a system which contains the momentum, Darcy and energy equations, together with the boundary conditions involved, is given. The behavior of different nanofluids, such thatAu-water, Ag-waterandFe-wateris graphically illustrated and compared with the previous results.The research target is to observe the substantial increase of the thermophysical fluid properties, when the porous medium issaturated by a nanofluid instead of a classical Newtonian fluid.

Numerical Analysis of Flare Gas Recovery Ejector

2014 ◽  
Author(s):  
Arihant Sonawat ◽  
Abdus Samad ◽  
Afshin Goharzadeh
Keyword(s):  
Fluid Flow ◽  
Flow Rate ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Gas Industry ◽  
Gas Recovery ◽  
System A ◽  
Primary Fluid ◽  
Recovery System ◽  
Flow Through

Flaring and venting contributes significantly to greenhouse gas emissions and environmental pollution in the upstream oil and gas industry. Present work focuses on a horizontal flow, multiphase ejector used for recovery of these flared gases. The ejector typically handles these gases being entrained by high pressure well head fluid and a comprehensive understanding is necessary to design and operate such recovery system. A CFD based analysis of the flow through the ejector has been reported in this paper. The flow domain was meshed and the mass and momentum equations for fluid flow were solved using commercial software CFX (v14.5). Euler-Euler multiphase approach was used to model different phases. The entrainment behavior of the ejector was investigated and compared for different fluid flow conditions. It was observed that for a fixed primary fluid flow rate, the entrained or secondary flow rate decreased linearly with an increase in pressure difference between exit and suction pressure. The higher was primary flow rate, the greater was the suction created ahead of the primary nozzle and greater was the amount of energy added to the entrained fluid.

Experimental Measurement of Fluid Flow Through the Grinding Zone

1992 ◽  
Vol 114 (1) ◽  
pp. 61-66 ◽  
Author(s):  
F. Engineer ◽  
C. Guo ◽  
S. Malkin
Keyword(s):  
Fluid Flow ◽  
Flow Rate ◽  
Depth Of Cut ◽  
Grinding Wheel ◽  
Surface Porosity ◽  
Test Rig ◽  
Useful Flow Rate ◽  
Useful Flow ◽  
Nozzle Position ◽  
Flow Through

An experimental test rig was developed to measure the amount of grinding fluid which flows through the grinding zone in straight plunge grinding. Proportional relationships were generally obtained between the flow rate from the nozzle and the useful flow rate of fluid passing through the grinding zone. The percentage of applied fluid passing through the grinding zone was found to depend mainly on the bulk porosity of the grinding wheel and the nozzle position. Wheel dressing has only a secondary influence, which is attributed to its influence on the surface porosity of the wheel. The workspeed and wheel depth of cut have virtually no influence.

Pulsatile flow in rigid tubes

1965 ◽  
Vol 20 (5) ◽  
pp. 1078-1082 ◽  
Author(s):  
Robert G. Linford ◽  
Norman W. Ryan
Keyword(s):  
Fluid Flow ◽  
Pressure Gradient ◽  
Flow Rate ◽  
Pulsatile Flow ◽  
Fluid Velocity ◽  
Fluid Flow Rate ◽  
Tube Radius ◽  
Low Frequencies ◽  
Time Relationship ◽  
Fluid Properties

The purpose of this study was to examine critically the theoretical equations derived for pulsatile laminar flow in rigid straight tubes. These equations, presented in their most useful form by J. R. Womersley in 1955, give the fluid flow rate as a function of the pressure gradient-time relationship, pulse frequency, fluid properties, and tube radius, and they give the fluid velocity as a function of the above quantities and the radial position in the tube. A pulsatile flow apparatus was constructed which would allow measurement of all the variables mentioned above, and a computer program based on Womersley's equations was used to calculate the fluid flow rate and velocity profile from the pressure gradient-time relationship, fluid properties, and tube radius. Thus a comparison between measured and calculated values of flow and velocity could be made. Calculations and data agree within the estimated experimental error, thus providing evidence of the applicability of the theoretical equations to actual flow with large pulse amplitudes. The analog computer “pressure gradient technique” of D. Fry and associates was compared with the exact solution for straight rigid tubes and found to deviate less than 20% in amplitude and phase except at very low frequencies. hydrodynamics, pulsatile flow; blood flow, arterial; hemodynamics, pulse characteristics Submitted on April 6, 1964

Hydraulic Resistance and Permeability in Human Lumbar Vertebral Bodies

2002 ◽  
Vol 124 (5) ◽  
pp. 533-537 ◽  
Author(s):  
Ruth S. Ochia ◽  
Randal P. Ching
Keyword(s):  
Fluid Flow ◽  
Hydraulic Resistance ◽  
High Speed ◽  
Lumbar Vertebrae ◽  
Pressure Flow ◽  
Flow Rates ◽  
Flow Through ◽  
Vertebral Bodies ◽  
The Mean ◽  
The Creation

Hydraulic resistance (HR) was measured for ten intact human lumbar vertebrae to further understand the mechanisms of fluid flow through porous bone. Oil was forced through the vertebral bodies under various volumetric flow rates and the resultant pressure was measured. The pressure-flow relationship for each specimen was linear. Therefore, HR was constant with a mean of 2.22±1.45kPa*sec/ml. The mean permeability of the intact vertebral bodies was 4.90×10−10±4.45×10−10m2. These results indicate that this methodology is valid for whole bone samples and enables the exploration of the effects of HR on the creation of high-speed fractures.

Fluid flow through the hydraulic resistance with a dynamically variable geometry

2017 ◽  
Vol 12 (1) ◽  
pp. 59-66 ◽  
Author(s):  
I.Sh. Nasibullayev ◽  
E.Sh. Nasibullaeva
Keyword(s):  
Fluid Flow ◽  
Hydraulic Resistance ◽  
Flow Rate ◽  
Dynamic Change ◽  
Variable Geometry ◽  
Transverse Compression ◽  
Flat Channel ◽  
Channel Geometry ◽  
Flow Through ◽  
Through Hole

In this paper the fluid flow in a flat channel with a hydraulic resistance is studied for two cases of a dynamic change in the channel geometry: transverse compression of the opening of the hydraulic resistance (the flow is caused by a pressure drop applied to the layer) and longitudinal movement of the hydraulic resistance along the channel (the flow is caused by this movement). It is obtained that in a geometry with transverse compression the flow is laminar without the formation of vortices. In a geometry with longitudinal movement of the hydraulic resistance the flow rate of the liquid remains constant with the formation of stable vortices that move along the channel at the rate of motion of the hydraulic resistance. On the base of the modeling results an analytical model that takes into account the flow rate of the fluid from the width of the through hole of the resistance is constructed. This model contains four interpolation parameters and it can be used as an element of a computational stand for determining the generalized flow of liquid in the system under consideration.

A Numerical Study of Natural Convection Inside an Automobile Compartment Due to Solar Radiation

2009 ◽  
Author(s):  
Md. Faisal Kader ◽  
Yong-du Jun ◽  
Kum-bae Lee
Keyword(s):  
Fluid Flow ◽  
Solar Radiation ◽  
Numerical Study ◽  
Three Dimensional ◽  
Scale Model ◽  
Design Parameters ◽  
Three Dimensional Model ◽  
Flow And Heat Transfer ◽  
Flow Through ◽  
Paper Address

In summer, the temperature of a parked automobile compartment increases extremely high under a sunny condition. Investigation of this fluid flow and heat transfer characteristics is very important for controlling the effect of major design parameters. This paper address the behavior of fluid flow through convection and air temperature inside a car parked in the sun. The numerical solution was done by a new and operation friendly CFD code – SC/Tetra with a full scale model of a SM3 car and turbulence was modeled by the standard k-ε equation. It can be seen that solar radiation is an important parameter to raise the compartment temperature above the ambient temperature during summer. Numerical analysis of the three-dimensional model predicts a detailed description of fluid flow and temperature distribution driven by the incoming solar radiation (insoaltion) in the passenger compartment.

Leakage Performance and Rotordynamic Characteristics of Bump Floating Ring Seals for Turbopump

2014 ◽  
Author(s):  
Yong-Bok Lee ◽  
Kyoung-Wook Kim ◽  
Sol-Ji Ryu ◽  
Jin Taek Chung
Keyword(s):  
Frequency Ratio ◽  
High Speed ◽  
Foil Thickness ◽  
Design Parameters ◽  
Rotor Speed ◽  
Damping Force ◽  
Rotating Speed ◽  
Rotordynamic Coefficients ◽  
Attitude Angle ◽  
Ring Seal

Floating ring seal with bump foil (BFRS) was newly proposed and tested. BFRS which has a thickness of bump (0.076, 0.1 and 0.12 mm) are separately tested for pressure-drops of 3.0, 5.0 and 7.0 MPa and rotor-speed up to 24,800 rpm. The measured data included leakage performance, attitude angle, lock-up eccentric ratio, and rotordynamic coefficients such as stiffness, damping and equivalent whirl frequency ratio to decide the whirling stability of seal were compared with floating ring seal. When the thickness of bump floating ring seals is increasing, leakage flow rate somewhat increases. Also, the lock-up eccentric ratio of the bump floating ring seal with large thickness is lower than that of the floating ring seal or small thickness of bump foil. The attitude angle increases linearly with the operating speeds in both cases. The direct damping coefficients increase significantly with the increments in bump-foil thickness and hydrostatic pressure-drop, but diminish with the rising rotor-speed. Especially, Coulomb friction damping force between the bump foil and housing surface contributes to the enhancement of direct damping coefficient value. Whirl frequency ratio of the floating ring seal without bump shows somewhat small in low speed ranges. When bump foil thickness is 0.074mm or 0.1mm, WFR is insensitive in rotating speed and pressure. But BFRS (0.12mm) shows up more stable tendency according to decreasing whirl frequency ratio in high speed ranges. The design parameters determined from these test results will be used to enhance the stability in high pressure and high speed turbomachinery seals.

scholarly journals Effect of Swirl on Rotordynamic Forces Caused by Front Shroud Pump Leakage

2002 ◽  
Vol 124 (4) ◽  
pp. 1005-1010 ◽  
Author(s):  
Yun Hsu ◽  
Christopher E. Brennen
Keyword(s):  
Fluid Flow ◽  
Flow Rate ◽  
Leakage Flow ◽  
Unsteady Forces ◽  
Low Leakage ◽  
Leakage Path ◽  
Leakage Flow Rate ◽  
Inlet Swirl ◽  
Flow Through ◽  
Rotordynamic Forces

Unsteady forces generated by fluid flow through the impeller shroud leakage path of a centrifugal pump were investigated. The effect of leakage path inlet swirl (pump discharge swirl) on the rotordynamic forces was re-examined. It was observed that increasing the inlet swirl is destabilizing both for normal and tangential rotordynamic forces. Attempts to reduce the swirl within the leakage path using ribs and grooves as swirl brakes showed benefits only at low leakage flow rate.

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