Flow Phenomena of Partially Enclosed Rotating Disks

1960 ◽  
Vol 82 (3) ◽  
pp. 539-549 ◽  
Author(s):  
L. A. Maroti ◽  
G. Deak ◽  
F. Kreith
Keyword(s):  
Flow Pattern ◽  
Side Wall ◽  
Rotating Disk ◽  
Reynolds Numbers ◽  
Frictional Torque ◽  
Gap Size ◽  
Rotating Disks ◽  
Disk Speed ◽  
Flow Phenomena ◽  
Source Flow

The flow of air in the space between a rotating disk and a stationary side wall placed parallel to its surface has been investigated over a range of Reynolds numbers from 3 × 105 to 6 × 106 at clearance-to-diameter ratios from 0.0125 to 0.0625. When the size of the stationary side wall was larger than the diameter of the rotating disk the flow in the gap was found to be periodic; several distinct and separate inflow and outflow regions were observed to rotate in the same direction as the disk, but at a slower speed. The number of flow regions was found to be a function of the disk speed and the gap size. The frictional torque on the housing was also measured and the effect of source flow on the flow pattern was studied qualitatively.

Mass and Heat Transfer From an Enclosed Rotating Disk With and Without Source Flow

1963 ◽  
Vol 85 (2) ◽  
pp. 153-162 ◽  
Author(s):  
Frank Kreith ◽  
E. Doughman ◽  
H. Kozlowski
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Rotating Disk ◽  
Reynolds Numbers ◽  
Correlation Equation ◽  
Rotating Disks ◽  
Transfer Coefficients ◽  
Transfer Rates ◽  
Smoke Visualization ◽  
Source Flow

The heat-transfer characteristics of a partially enclosed rotating disk have been investigated experimentally by means of a mass-transfer analog. Mass-transfer rates to air from naphthalene coated disks of 4 and 8 in. diameter were measured at speeds between zero and 10,000 rpm and the influence of the spacing between the rotating disk and its housing was investigated with and without source flow. From the experimental results a dimensionless correlation equation suitable for predicting average heat and mass-transfer coefficients for rotating disks with source flow in turbulent flow at rotational Reynolds numbers up to 4 × 105 was deduced. The flow pattern was investigated by means of a hot wire, a smoke visualization technique, and the china clay method.

Inward Flow Between Stationary and Rotating Disks

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Achhaibar Singh
Keyword(s):  
Laminar Flow ◽  
Flow Field ◽  
Velocity Distribution ◽  
Stokes Equations ◽  
Tangential Velocity ◽  
Rotating Disk ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Rotating Disks ◽  
Navier Stokes Equations

The present study predicts the flow field and the pressure distribution for a laminar flow in the gap between a stationary and a rotating disk. The fluid enters through the peripheral gap between two concentric disks and converges to the center where it discharges axially through a hole in one of the disks. Closed form expressions have been derived by simplifying the Navier– Stokes equations. The expressions predict the backflow near the rotating disk due to the effect of centrifugal force. A convection effect has been observed in the tangential velocity distribution at high throughflow Reynolds numbers.

Vibration Measurement and Monitoring of a Rotating Disk Using Contactless Laser Excitation

2013 ◽  
Author(s):  
Itsuro Kajiwara ◽  
Naoki Hosoya
Keyword(s):  
Laser Doppler Vibrometer ◽  
Rotating Disk ◽  
Disk Drive ◽  
Vibration Characteristics ◽  
Vibration Measurement ◽  
Testing System ◽  
Rotating Disks ◽  
Vibration Testing ◽  
Structural Surface ◽  
Theoretical Analyses

This paper proposes a contactless vibration testing system for rotating disks based on an impulse response excited by a laser ablation. High power YAG pulse laser is used in this system for producing an ideal impulse force on structural surface without contact. The contactless vibration testing system is composed of a YAG laser, laser Doppler vibrometer and spectrum analyzer. This system makes it possible to measure vibration characteristics of structures under operation, such as vibration measurement of a rotating disk. The effectiveness of this system is confirmed by experimental and theoretical analyses. In this paper, a platter of hard disk drive is employed as an experimental object. Vibration characteristics of a rotating and non-rotating platter are measured and compared with the results of theoretical analysis.

Experimental Investigation of Subsonic Turbulent Flow Over Single and Double Backward Facing Steps

1962 ◽  
Vol 84 (3) ◽  
pp. 317-325 ◽  
Author(s):  
D. E. Abbott ◽  
S. J. Kline
Keyword(s):  
Experimental Investigation ◽  
Velocity Profile ◽  
Flow Pattern ◽  
Reynolds Numbers ◽  
Area Ratio ◽  
Single Step ◽  
Reattachment Length ◽  
Double Step ◽  
Wide Range ◽  
Geometric Variables

Results are presented for flow patterns over backward facing steps covering a wide range of geometric variables. Velocity profile measurements are given for both single and double steps. The stall region is shown to consist of a complex pattern involving three distinct regions. The double step contains an assymmetry for large expansions, but approaches the single-step configuration with symmetric stall regions for small values of area ratio. No effect on flow pattern or reattachment length is found for a wide range of Reynolds numbers and turbulence intensities, provided the flow is fully turbulent before the step.

Magnetohydrodynamic lubrication flow between parallel rotating disks

1962 ◽  
Vol 13 (1) ◽  
pp. 21-32 ◽  
Author(s):  
W. F. Hughes ◽  
R. A. Elco
Keyword(s):  
Magnetic Field ◽  
Axial Magnetic Field ◽  
Load Capacity ◽  
Electrical Energy ◽  
Axial Current ◽  
Frictional Torque ◽  
Rotating Disks ◽  
Radial Magnetic Field ◽  
Electrically Conducting ◽  
Parallel Disks

The motion of an electrically conducting, incompressible, viscous fluid in the presence of a magnetic field is analyzed for flow between two parallel disks, one of which rotates at a constant angular velocity. The specific application to liquid metal lubrication in thrust bearings is considered. The two field configurations discussed are: an axial magnetic field with a radial current and a radial magnetic field with an axial current. It is shown that the load capacity of the bearing is dependent on the MHD interactions in the fluid and that the frictional torque on the rotor can be made zero for both field configurations by supplying electrical energy through the electrodes to the fluid.

Nonlinear Resonant Motion of Traveling Waves in Rotating Disks

2000 ◽  
Author(s):  
Albert C. J. Luo ◽  
Chin An Tan
Keyword(s):  
Traveling Waves ◽  
Rotation Speed ◽  
Rotating Disk ◽  
Disk Drive ◽  
Computer Memory ◽  
Rotating Disks ◽  
Resonant Wave ◽  
Linear And Nonlinear ◽  
Resonant Spectrum ◽  
Disk Drive Industry

Abstract The resonant conditions for traveling waves in rotating disks are derived. The nonlinear resonant spectrum of a rotating disk is computed from the resonant conditions. Such a resonant spectrum is useful for the disk drive industry to determine the range of operational rotation speed. The resonant wave motions for linear and nonlinear, rotating disks are simulated numerically for a 3.5-inch diameter computer memory disk.

Experimental Analysis of a NACA 0021 Airfoil Under Dynamic Angle of Attack Variation and Low Reynolds Numbers

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
D. Holst ◽  
B. Church ◽  
F. Wegner ◽  
G. Pechlivanoglou ◽  
C. N. Nayeri ◽  
...  
Keyword(s):  
Design Process ◽  
Surface Pressure ◽  
Wind Turbines ◽  
Full Range ◽  
Vertical Axis ◽  
Reynolds Numbers ◽  
Time Resolved ◽  
Pressure Distributions ◽  
Pressure Development ◽  
Flow Phenomena

The wind industry needs reliable and accurate airfoil polars to properly predict wind turbine performance, especially during the initial design phase. Medium- and low-fidelity simulations directly depend on the accuracy of the airfoil data and even more so if, e.g., dynamic effects are modeled. This becomes crucial if the blades of a turbine operate under stalled conditions for a significant part of the turbine's lifetime. In addition, the design process of vertical axis wind turbines needs data across the full range of angles of attack between 0 and 180 deg. Lift, drag, and surface pressure distributions of a NACA 0021 airfoil equipped with surface pressure taps were investigated based on time-resolved pressure measurements. The present study discusses full range static polars and several dynamic sinusoidal pitching configurations covering two Reynolds numbers Re = 140k and 180k, and different incidence ranges: near stall, poststall, and deep stall. Various bistable flow phenomena are discussed based on high frequency measurements revealing large lift-fluctuations in the post and deep stall regime that exceed the maximum lift of the static polars and are not captured by averaged measurements. Detailed surface pressure distributions are discussed to provide further insight into the flow conditions and pressure development during dynamic motion. The experimental data provided within the present paper are dedicated to the scientific community for calibration and reference purposes, which in the future may lead to higher accuracy in performance predictions during the design process of wind turbines.

Thermo-mechanical analysis and optimization of functionally graded rotating disks

2020 ◽  
Vol 55 (5-6) ◽  
pp. 159-171
Author(s):  
Hassan Mohamed Abdelalim Abdalla ◽  
Daniele Casagrande ◽  
Luciano Moro
Keyword(s):  
Finite Element ◽  
Equivalent Stress ◽  
Rotating Disk ◽  
Mechanical Analysis ◽  
Theory Of Elasticity ◽  
Functionally Graded ◽  
Rotating Disks ◽  
Maximum Equivalent Stress ◽  
Quadratic Programming Method ◽  
Stress Uniformity

The behavior of thermo-mechanical stresses in functionally graded axisymmetric rotating hollow disks with variable thickness is analyzed. The material is assumed to be functionally graded in the radial direction. First, a two-dimensional axisymmetric model of the functionally graded rotating disk is developed using the finite element method. Exact solutions for stresses are then obtained assuming that the plane theory of elasticity holds. These solutions are in accordance with finite element ones, thus showing the validity of the assumption. Finally, in order to reduce the maximum equivalent stress along the radius, the optimization of the material distribution is addressed. To avoid subsequent finite element simulations in the optimization process, which can be computationally demanding, a nonlinear constrained optimization problem is proposed, for which the solution is obtained numerically by the sequential quadratic programming method, showing prominent results in terms of equivalent stress uniformity.

scholarly journals Lattice Boltzmann simulation of two-sided lid-driven flow in deep cavities

2015 ◽  
pp. 157-168
Author(s):  
Natasa Lukic ◽  
Predrag Tekic ◽  
Jelena Radjenovic ◽  
Ivana Sijacki
Keyword(s):  
Aspect Ratio ◽  
Flow Pattern ◽  
Lattice Boltzmann ◽  
Reynolds Numbers ◽  
Critical Aspect ◽  
Symmetric Flow ◽  
Primary Vortex ◽  
Lattice Boltzmann Simulation ◽  
Boltzmann Method ◽  
Deep Cavities

The present study is concerned with two-sided lid-driven incompressible flow in rectangular, deep cavities applying lattice Boltzmann method. After validating the code for the square cavity, solutions for cavities with an aspect ratio 1.5 and 4 were obtained for the Reynolds numbers of 100, 400, 1000 and 3200. The influence of the Reynolds number and aspect ratio on the flow pattern and on the characteristics of vortices inside the cavity was studied. Symmetric flow pattern was obtained for all investigated cases. The middle of the cavity is mostly influenced by the increase in the aspect ratio. Critical aspect ratio, at which the birth of a primary vortex in the middle of the cavity takes place, was determined to be between 2.7 and 2.725.

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