### Contents of Journal of Mechanical Engineering *55,* 6 (2004)

DZIANIK, F., VAVRO, K.: Calculation of the separation efficiency
of cyclone apparatus 315
GUŽELA, Š., PECIAR, M., FEKETE, R.: Mixing of particulate
materials – experimental input power estimation 329
DOMANOVÁ, M., DZIANIK, F., JELEMENSKÝ, K.:
Study of tangential velocity component in helical (swirling)
annulus flow 341
VARCHOLA, M., KNÍŽAT, B., TÓTH, P., GOLHA, M.: Hydraulic design
of a spiral pump respecting the course of characteristics and radial
thrust on the rotor 356

# Abstracts

### Calculation of the separation efficiency of cyclone apparatus

FRANTIŠEK DZIANIK, KAROL VAVRO

There are a few definitions for the calculation of the separation
efficiency of cyclone apparatus. However, none of them is suitable for the
expression of the separation efficiency at specific operating conditions of
cyclones. The definition derived by Kelsall is the nearest one to achieve
correct evaluation of the separation efficiency at such operating conditions of
cyclones. A new definition of the separation efficiency was derived from
Kelsall's definition by the implementation of additional term. This term
considers possible variations of operating conditions of the cyclone apparatus
so that at the same time calculated values of the separation efficiency are
qualitatively comparable and they reflect the real status as exactly as
possible. The separation efficiency was expressed by the relative underflow of
the suspension and the relative underflow of the particles. Values of these
distribution ratios were obtained by measuring at various operating conditions
of the experimental hydrocyclone. Within a presentation of the results the
comparison between the evaluation of the separation efficiency according to the
new definition and according to Kelsall's definition was introduced. From
presented results it follows that the separation efficiency evaluation by the
new definition is more exact.

### Mixing of particulate materials – experimental input power estimation

ŠTEFAN GUŽELA, MARIÁN PECIAR, ROMAN FEKETE

Granular materials are treated in various branches of industry where
it is necessary to insure the moving objects (mixing elements) of various shapes
through batch of granular materials. The force effects of the mixed material on
the moving blade submerged in the granular material have been measured. Solution
starts with limit equilibrium stresses of the granular material described by
Mohr's circle. The experimental station in the shape of rectangular prism for
determining the effective force vector, i.e. the horizontal and vertical
components of force was used, which enables only uniform rectilinear motion of
the blending elements. A semi-empirical correlation based on elementary soil
mechanics theory is presented.

### Study of tangential velocity component in helical (swirling) annulus
flow

MARTINA DOMANOVÁ, FRANTIŠEK DZIANIK, KAROL JELEMENSKÝ

Increase in the transfer properties intensity at fluids flowing in
the devices is reachable by various means. Swirling motion of the fluid around
the equipment axis is ensured by entering the fluid through a tangential inlet
into the annular gap of the vertical heat exchanger model. This type of the flow
can be characterized as gradually decaying. The tangential component of velocity
is responsible for the increase in swirl intensity in this case. The degree of
swirl along the model length is properly described with non-dimensional
criterion *S* – swirl intensity or swirl number, by Gupta et al. defined as
the ratio of axial flux of swirl momentum and axial flux of axial momentum
multiplied by equivalent dimension. Measurements of average values of the axial
and tangential velocity components were realized with the laser, by the Laser
Doppler Anemometry method. From the specified criterion relations for mean and
local values of swirl intensity, obtained from measured data, the mean and local
values of tangential velocity component along the gap width for the specific
geometry and volume flow can be expressed.

### Hydraulic design of a spiral pump respecting the course of characteristics and
radial thrust on the rotor

MICHAL VARCHOLA, BRANISLAV KNÍŽAT, PETER TÓTH, MIROSLAV GOLHA

In the paper there is described the procedure and theoretical
background of a pump hydraulic design. Designed geometry is a basis for the
calculation of a possible pump characteristics and considers the losses in a
pump.
In the paper there is mentioned the principle of the losses calculation in a
pump, which is important for numerical solution of differential equations. The
result of the calculation is the pump Q-Y characteristics. In the paper there is
described the example of the calculation and its results are compared with
measured ones. This paper deals with a theoretical computation of the radial
thrust, which is induced by a non-uniformity of the static pressure and the
velocity distribution at the impeller outlet area, and due to non-uniformity of
the static pressure on the curved area of impeller shrouds. Paper shows the
comparison of calculated and measured values of the single impeller with
conventional spiral casing.