On the Ertel and Impermeability Theorems for Slightly Viscous Currents in Stratified Rotating Systems

Rotating systems components such as rotors, have dynamic characteristics that are of great importance to understand because they may cause failure of turbomachinery. Therefore, it is required to study a dynamic model to predict some vibration characteristics, in this case, the natural frequencies and mode shapes (both of free vibration) of a centrifugal compressor shaft. The peculiarity of the dynamic model proposed is that using frequency and displacements values obtained experimentally, it is possible to calculate the mass and stiffness distribution of the shaft, and then use these values to estimate the theoretical modal parameters. The natural frequencies and mode shapes of the shaft were obtained with experimental modal analysis by using the impact test. The results predicted by the model are in good agreement with the experimental test. The model is also flexible with other geometries and has a great time and computing performance, which can be evaluated with respect to other commercial software in the future.

Download Full-text

Unsteady Flow Phenomena in Rotating Centrifugal Impeller Passages

Journal of Engineering for Power ◽

10.1115/1.3445302 ◽

1970 ◽

Vol 92 (1) ◽

pp. 65-71 ◽

Cited By ~ 25

Author(s):

E. Lennemann ◽

J. H. G. Howard

Keyword(s):

Unsteady Flow ◽

Secondary Flow ◽

Centrifugal Impeller ◽

Bubble Flow ◽

Hydrogen Bubble ◽

Visualization Technique ◽

Rotating Systems ◽

Flow Phenomena ◽

Relative Flow ◽

Zero Flow

The phenomena of unsteady relative flow observed in a centrifugal impeller passage running at part capacity and zero flow are discussed. The mechanisms of passage stall for a shrouded and unshrouded impeller are investigated and a qualitative correlation is developed for the influence of secondary flow and inducer flow on the passage stall. The hydrogen bubble flow visualization technique is extended to higher velocities and rotating systems and provides the method for obtaining the experimental results.

Download Full-text

A new concept of active hydrodynamic bearing for application in rotating systems

Tribology International ◽

10.1016/j.triboint.2020.106592 ◽

2021 ◽

Vol 153 ◽

pp. 106592

Author(s):

D.J. Ramos ◽

G.B. Daniel

Keyword(s):

Hydrodynamic Bearing ◽

Rotating Systems

Download Full-text

Pattern Formation Phenomena in Contact Rotating Systems. 1st Report, Simplified Method for Stability Analysis and Prevention Measure by Using Energy Factor.

TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series C ◽

10.1299/kikaic.67.2121 ◽

2001 ◽

Vol 67 (659) ◽

pp. 2121-2128 ◽

Cited By ~ 2

Author(s):

Takahiro KONDOU ◽

Nobuyuki SOWA

Keyword(s):

Stability Analysis ◽

Pattern Formation ◽

Energy Factor ◽

Rotating Systems ◽

Prevention Measure ◽

Simplified Method

Download Full-text

Rotor Dynamics Analysis of Rotating Machine Systems Using Artificial Neural Networks

International Journal of Rotating Machinery ◽

10.1155/s1023621x0300023x ◽

2003 ◽

Vol 9 (4) ◽

pp. 255-262 ◽

Cited By ~ 5

Author(s):

M. Kalkat ◽

Ş. Yıldırım ◽

I. Uzmay

Keyword(s):

Neural Network ◽

Neural Networks ◽

Vertical Direction ◽

Rotor Dynamics ◽

Experimental Setup ◽

Dynamics Analysis ◽

Rotating Machine ◽

Rotating Systems ◽

Machine Systems ◽

Vibration Parameters

Adirect-coupled rotor system was designed to analyze the dynamic behavior of rotating systems in regard to vibration parameters. The vibration parameters are amplitude, velocity, and acceleration in the vertical direction. The system consisted of a machine analyzer, shaft, disk, master-trend software, and power unit. Four different points were detected and measured by the experimental setup. The vibration parameters were found and saved from master-trend software. These parameters were employed as the desired parameters of the network. A neural network is designed for analyzing a system's vibration parameters. The results showed that the network could be used as an analyzer of such systems in experimental applications.

Download Full-text

The Antonov problem for rotating systems

Nuclear Physics B ◽

10.1016/s0550-3213(03)00050-6 ◽

2003 ◽

Vol 654 (3) ◽

pp. 427-444 ◽

Cited By ~ 7

Author(s):

A. De Martino ◽

E.V. Votyakov ◽

D.H.E. Gross

Keyword(s):

Rotating Systems

Download Full-text

The macrodynamics of α-effect dynamos in rotating fluids

Journal of Fluid Mechanics ◽

10.1017/s0022112075000390 ◽

1975 ◽

Vol 67 (3) ◽

pp. 417-443 ◽

Cited By ~ 140

Author(s):

W. V. R. Maekus ◽

M. R. E. Proctor

Keyword(s):

Magnetic Fields ◽

Large Scale ◽

Magnetic Energy ◽

Finite Amplitude ◽

Small Scale ◽

Past Study ◽

Ohmic Loss ◽

General Will ◽

Rotating Systems ◽

Stellar Magnetic Fields

Past study of the large-scale consequences of forced small-scale motions in electrically conducting fluids has led to the ‘α-effect’ dynamos. Various linear kinematic aspects of these dynamos have been explored, suggesting their value in the interpretation of observed planetary and stellar magnetic fields. However, large-scale magnetic fields with global boundary conditions can not be force free and in general will cause large-scale motions as they grow. I n this paper the finite amplitude behaviour of global magnetic fields and the large-scale flows induced by them in rotating systems is investigated. In general, viscous and ohmic dissipative mechanisms both play a role in determining the amplitude and structure of the flows and magnetic fields which evolve. In circumstances where ohmic loss is the principal dissipation, it is found that determination of a geo- strophic flow is an essential part of the solution of the basic stability problem. Nonlinear aspects of the theory include flow amplitudes which are independent of the rotation and a total magnetic energy which is directly proportional to the rotation. Constant a is the simplest example exhibiting the various dynamic balances of this stabilizing mechanism for planetary dynamos. A detailed analysis is made for this case to determine the initial equilibrium of fields and flows in a rotating sphere.

Download Full-text

Simulation of Cooling Systems in Gas Turbines

Journal of Turbomachinery ◽

10.1115/1.2836640 ◽

1996 ◽

Vol 118 (2) ◽

pp. 301-306 ◽

Cited By ~ 2

Author(s):

G. Ebenhoch ◽

T. M. Speer

Keyword(s):

Gas Turbines ◽

Path Following ◽

Cooling Systems ◽

Turbine Engine ◽

Rotating Systems ◽

Entire Flow ◽

Flow Pressure ◽

The One ◽

Single Flow ◽

Flow Element

The design of cooling systems for gas turbine engine blades and vanes calls for efficient simulation programs. The main purpose of the described program is to determine the complete boundary condition at the coolant side to support a temperature calculation for the solid. For the simulation of convection and heat pick up of the coolant flow, pressure loss, and further effects to be found in a rotating frame, the cooling systems are represented by networks of nodes and flow elements. Within each flow element the fluid flow is modeled by a system of ordinary differential equations based on the one-dimensional conservation of mass, momentum, and energy. In this respect, the computer program differs from many other network computation programs. Concerning cooling configurations in rotating systems, the solution for a single flow element or the entire flow system is not guaranteed to be unique. This is due to rotational forces in combination with heat transfer and causes considerable computational difficulties, which can be overcome by a special path following method in which the angular velocity is selected as the parameter of homotopy. Results of the program are compared with measurements for three applications.

Download Full-text