A three-axis plot of laterally averaged film cooling effectiveness versus blowing rate and versus dimensionless distance
downstream is a sufficiently compact representation of film cooling effectiveness data for injection through a row of holes
or two rows of holes to enable easy, global comparisons among a variety of data sets. By plotting data from several film
cooling studies conducted at the University of Minnesota, the dominant roles played by density ratio, hole spacing, and
surface curvature become apparent. It is also seen that a slot-plate prediction/correlation from two-dimensional film cooling
studies makes an excellent standard of comparison for all film cooling studies, even though the more commonly encountered
(two-axis) comparisons using standardized nondimensional parameters do not usually suggest this.

L. D. Stone

R. J. Goldstein

Film Cooling Effectiveness Data for Simple Injection
Geometries: A Collection of Three-Axis Plots

Considerable improvements of machines can be expected in the near future through the use ofelectronics in combination with
control techniques. A key position will be held by the actuator systems that finally have to accomplish the controlled energy
transfer according to the objectives. For rotating machine parts this is usually done via the bearings. Basically, there are two
possibilities to transmit the controlled forces; contact free via magnetic fields (magnetic bearings) or the traditional way via
conventional bearings. To realize the regulating actions multiple physical effects can be employed. In this paper some of the
promising types of actuators and their advantages and disadvantages will be discussed, as well as how effectively to use these
active elements under different objectives. Questions concerning the practical realizations will be given high priority.

Heinz Ulbrich

Comparison of Different Actuator Concepts for
Applications in Rotating Machinery

Fluiddynamic interaction between rotor and stator generates local pressure fluctuation and can be a cause ofstructural vibration
of turbomachines. The interaction produces a spatial distribution of pressure fluctuation with a certain diametrical mode and
propagating speed, known as rotating pressure field. When the frequency and mode of a rotating pressure field coincide
with those of the structural vibration, a fluid-excited resonance takes place, leading to eventual severe structural damage. An
example of such damage is described in detail using the case of PLR pump failure of a BWR plant.

Hideo  Ohashi

Case Study of Pump Failure Due to Rotor-Stator Interaction

The problem of steam whirl is one of the technological limits that now prohibit the development of power-generating
turbomachinery substantially above GW. Due to steam flow, self-excited vibrations develop at high loads in the form of
stable limit cycles that, at even higher loads, deteriorate to chaotic vibration of high amplitude.A mathematical model is developed for stability analysis and for the development of a rational stability criterion to be
used at the design stage. The bearing nonlinearity is introduced in the form of high-order coefficients of a Taylor expansion of
the perturbation forces for fixed-arc slider bearings and employing nonlinear pad functions for the tilting pad bearings. The
flow excitation is introduced in the form of follower force gradients related to the flow and the power generated.The study of the stable and unstable limit cycles, and the stability of the system in the large, beyond the linear analysis
currently utilized, is done analytically for the De Laval rotor and numerically with finite element analysis of typical
turbomachinery rotors.The range of loads for which limit cycles exist was found to be substantial. This is important for the operation of
large machinery because such cycles permit the operation at loads much higher than the ones that correspond to the onset
of instability of the linearized system. The conditions for the limit cycle deterioration into chaotic orbit are investigated.
Analytical expressions have been obtained for the different stability thresholds for the De Laval rotor.

Andrew D. Dimarogonas

Julio C. Gomez-Mancilla

Flow-Excited Turbine Rotor Instability

The development of a wake flow downstream of a cylindrical rod within a curved channel under zero streamwise pressure
gradient is theoretically and experimentally investigated. The measured asymmetric wake quantities such as the mean velocity
and turbulent fluctuations in longitudinal and lateral directions as well as the turbulent shear stress are transformed from the
probe coordinate system into the curvilinear wake eigen-coordinate system. For the transformed nondimensionalized velocity
defect and the turbulent quantities, affine profiles are observed throughout the flow regime. Based on these observations and
using the transformed equations of motion and continuity, a theoretical framework is established that generally describes the
two-dimensional curvilinear wake flow. The theory also describes the straight wake as a special case, for which the curvature
radius approaches infinity. To demonstrate the general validity of theory, experimental results pertaining to curved wake as
well as straight wake flows are compared with the developed theory.

M. T. Schobeiri

K. Pappu

J. John

On the Development of Two-Dimensional Wakes within Curved 
Channels: Experimental and Theoretical Investigation

Experiments were conducted to investigate the effects of rotation and aspect ratio on the convective heat transfer of radially
outward air flows in rotating rectangular ducts with a uniform wall heat flux by using fiberglass duct walls lined with
separated film heaters. The duct hydraulic diameter, heater active length, and mean rotation radius were 4, 120, and 180 mm,
respectively. Ranges of parameters were through-flow Reynolds number, 1,000&#8211;15,000; rotation number, 0&#8211;0.32; rotational
buoyancy parameter, 0&#8211;1.2; and cross-sectional aspect ratio, 0.5, 1.0, and 2.0. The results showed that the higher the rotation
number, the greater the enhancement ofthe heat transfer rate especially at the pressure side. The rotational buoyancy parameter
decreases the heat transfer for low Re but enhances the heat transfer for high Re. The largest heat transfer enhancement is
seen for AR = 1.0, and the enhancement for AR = 0.5 is greater than that for AR = 2.0.

C. R. Kuo

G. J. Hwang

Aspect Ratio Effect on Convective Heat Transfer of Radially Outward Flow in 
Rotating Rectangular Ducts

Wen-Jei Yang

Editorial

About this journal

International Journal of Rotating Machinery publishes original research articles as well as review articles on all types of rotating machinery employing gas, vapor, particle, liquid, and their mixtures (including slurry) as the working substances.

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Chief Editor, Professor Amano, is based at the University of Wisconsin–Milwaukee and his research concentrates on the enhancement of energy production using wind, biomass, alternate fuels, and fossil energy sources.

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Databases and indexing

International Journal of Rotating Machinery - Table of contents 1994

International Journal of Rotating Machinery | Hindawi

title

International Journal of Rotating Machinery publishes original research articles as well as review articles on all types of rotating machinery employing gas, vapor, particle, liquid, and their mixtures (including slurry) as the working substances.

International Journal of Rotating Machinery