ArticlePDF Available

Experimental Study of Pneumatic Two-Stage Small-Size Radial Turbine

Authors:

Abstract

This work is aimed at experimental study of the influence of design variables of the first jet reaction stage on the properties of pneumatic two-stage small-size radial turbine. Kinematic layout of the considered turbine is presented, operating processes are described, the final target is formulated to reveal the influence of certain geometrical parameters of the first jet reaction stage which determine overall turbine efficiency. Criterion of nozzle efficiency is determined, variable parameters of multifactorial experiment are selected; experimental facility and procedure of data processing are described. The main experimental results are presented. It is established that the greatest influence on the turbine efficiency is exerted by supersonic nozzle expansion angle. Optimum combination of geometrical expansion extent and geometrical expansion angle of supersonic nozzle of the first jet reaction stage of two-stage small-size radial turbine has been experimentally determined.
Copyright © 2018 Authors. This is an open access article distributed under the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
International Journal of Engineering & Technology, 7 (4.38) (2018) 305-308
International Journal of Engineering & Technology
Website: www.sciencepubco.com/index.php/IJET
Research paper
Experimental Study of Pneumatic Two-Stage Small-Size Radial
Turbine
Yuri Pavlovich Kuznetsov1*, Lev Anatolevich Zakharov1, Sergey Nikolaevich Khrunkov1, Artem Aleksandrovich
Kraynov1, Aleksandr Evgenevich Zhukov1
1Nizhny Novgorod State Technical University n.a. R.E. Alekseev, Minin Str., 24, Nizhny Novgorod, 603950, Russia
*Corresponding author E-mail: kuznetsov.y.p@mail.ru
Abstract
This work is aimed at experimental study of the influence of design variables of the first jet reaction stage on the properties of pneumatic
two-stage small-size radial turbine. Kinematic layout of the considered turbine is presented, operating processes are described, the final
target is formulated to reveal the influence of certain geometrical parameters of the first jet reaction stage which determine overall
turbine efficiency. Criterion of nozzle efficiency is determined, variable parameters of multifactorial experiment are selected;
experimental facility and procedure of data processing are described. The main experimental results are presented. It is established that
the greatest influence on the turbine efficiency is exerted by supersonic nozzle expansion angle. Optimum combination of geometrical
expansion extent and geometrical expansion angle of supersonic nozzle of the first jet reaction stage of two-stage small-size radial
turbine has been experimentally determined.
Keywords: pneumatic drive, turbine drive, jet reaction turbine, Segner wheel, radial turbine, small-size turbine.
1. Introduction
Small-size turbines of various kinematic layouts are presently
used in engine manufacturing (superchargers) and in cryogenic
engineering (helium and hydrogen turboexpanders), in aircraft
engineering (cooling turbines, small-size gas turbine engines of
drones) and in power engineering (Zysin turbines, small-size
turbogenerators), in oil and gas industry (ball valve drive) and in
auxiliary mechanisms with pneumatic drive for spacecraft and
submersible vehicles, in commercial pneumatic tools.
Numerous designs of small-size turbines have been developed
according to various requirements but the most advantageous
designs both in terms of manufacturing and efficiency are
multistage radial turbines. Blade system of radial pneumatic
turbine can be manufactured in press mold by die casting of
plastics which significantly reduces its cost upon serial
production.
Aiming at manufacture of competitive pneumatic tool, the Chair
of power plants and thermal engines, Alekseev State Technical
University, Nizhny Novgorod developed and fabricated model
series of experimental manual pneumatic grinding machines.
Their main feature is the use of innovative two-stage radial turbine
where the first stage is comprised of radial jet reaction turbine,
and the second one - of radial centripetal turbine [1, 2, 3]. Both
stages are embodied on a single disk of operating wheel, which is
advantageous in terms of engineering and sizes of the design. This
kinematic layout provides efficient aerodynamic performances,
velocity and economic characteristics as well as possibility to
achieve almost any combination of power and rotation rate.
Kinematic layout of small-size two-stage radial turbine is
illustrated in Fig. 1.
Fig. 1: Kinematic layout of small-size two-stage radial turbine
As illustrated in the figure, working medium (compressed air) is
fed to the first stage (position 1) radially from the rotor center. In
fixed intermediate guiding apparatus (position 2) the flow gets
reversed and reaches the blade system of the second drive stage.
2. Analysis of Operation Processes
Predictions of variables of working medium flow along flowing
part of the two-stage pneumatic small-size turbine performed in
the scope of one-dimension stage theory have demonstrated that
the greatest contribution to the overall turbine efficiency is made
by the first stage: jet reaction rotating nozzle apparatus [4]. In jet
reaction turbine the reaction force is created only by
circumferential projection of outlet velocity [5, 6, 7]. With the
increase in angle between the outlet velocity vector C and
direction of tangent line to operating wheel in the outlet point, the
tangent component of reaction force and, hence, turbine efficiency
sharply drop. Therefore, in order to increase turbine efficiency in
terms of design, it is necessary to provide the minimum angle of
flow outlet. Triangles of velocity vectors at skewed nozzle outlet
are illustrated in Fig. 2.
International Journal of Engineering & Technology
306
Fig. 2: Schematic view of working medium outlet from turbine nozzle
Contradictory impact of various design nozzle parameters of the
first jet reaction stage (such as the ratio of inlet to outlet nozzle
surface areas, nozzle length, position of nozzle axial line and some
others) on the properties of pneumatic small-size radial turbine
requires for experimental studies. The necessity to study
efficiency of jet reaction turbine is also related with the
dimensions: in small-size turbines, due to high relative roughness
and relative gaps, operation processes can be described
insufficiently using conventional predictions of pneumatic
turbines.
3. Design of Experiment
Velocity factor of nozzle apparatus of jet reaction turbine (the
ratio of actual flow rate of working medium from nozzle to
isentropic flow rate from the same nozzle) was selected as the
target function. In order to reduce expenses for experiments, the
experimental design theory was applied. Variables (the considered
factors) of jet reaction turbine were selected on the basis of
analysis of a priori information on the influence of factors. Among
all geometric factors affecting turbine efficiency, such as
geometric angle of flow exit, expansion angle of supersonic
nozzle, length of nozzle sub- and supersonic portions, decrease
rate of air pressure in supersonic portion, the most significant ones
were selected. It is known that the variables of supersonic nozzle
have more significant influence on the efficiency of its operation
than the variables of subsonic portion. Hence, two factors were
selected for the experiments: geometrical expansion angle of
supersonic portion
γ
and geometrical channel expansion rate in
supersonic portion F/f, which was the ratio of outlet surface area
of the nozzle 1 to its critical surface area 2, Fig. 3. Other assumed
factors had either lower or known influence on the target function,
hence, they were assumed constant in the experiments.
Fig. 3: Factors for studying nozzle efficiency
The next task was determination of domain of the selected factors.
Expansion angle of supersonic portion can vary from γ = 0° to γ =
40°. These limits are of engineering character, since it is required
to install several nozzles on constrained surface of operating
wheel, leaving free segments in order to vary this factor. From the
same considerations, the domain boundaries of geometrical
channel expansion rate in supersonic portion F/f are from 1.0 to
1.6.
The design of the first series of two-factor experiment, according
to the steepest ascent method, included 5 combinations of factors.
They were comprised of one reference point (point «0») and 4
points in the vicinities, covering all 4 main possible directions of
gradient vector. In order to define correctly parameters of
reference point, a priori information was very important. From the
point of view of gas dynamics, the optimum values of the selected
factors for reference point were as follows: γ=8…12°, F/f=1,53 [8,
9, 10, 11, 12, 13, 14], Fig. 4. In the first experimental series the
step for geometrical expansion rate F/f was set to ΔF/f=0.1, and the
step of geometrical expansion angle of supersonic portion γ was
set to Δγ=2°. According to the experimental design, 5 operating
wheels were developed and manufactured for the first
experimental series. The wheels were manufactured by 3D
printing. Drawings and photos of the experimental operating
wheels are shown in Fig. 5.
Fig. 4: Reference point and region of factor variation
Fig. 5: Experimental operating wheels:
a) reference point, b, c), d), e) points 1–4, f) photograph of operating
wheels.
4. Experimental Facility
The main properties of experimental turbines were determined on
the experimental facility for stages and blade systems of small-
size turbines [15] illustrated in Fig. 6. The considered nozzle
apparatus 5 is mounted in the body 4 into the coupling of gas
static suspension 8 which, due to gas layer, prevents mechanical
contact with the fixed rim 7 thus improving the accuracy of
measurements. Air is supplied to the gas static suspension via the
tubes 2. The working medium is supplied to the considered nozzle
apparatus via 3 tubes, position 3, located radially to the receiver in
120° in the plane perpendicular to cylinder axis. The labyrinth
sealings 6 are intended for decrease in air leakage from air supply
system to the nozzle apparatus. The torque created by the nozzle
apparatus is transferred to the moving coupling of the gas static
suspension 8 and is detected by the torque strain sensor 10.
Fig. 6: Experimental facility for studying the nozzle apparatuses: 1
receiver; 2air inlet tube to gas static suspension; 3air inlet tube to the
considered nozzle apparatus; 4body for mounting of nozzle apparatus; 5
the considered nozzle apparatus; 6 labyrinth sealing;
7 static rim of gas static suspension; 8 coupling of gas static
suspension; 9flange of gas static suspension; 10torque strain sensor.
While measuring torque created by nozzle apparatus, the torque
sensor of the facility detects cumulative flow rate of working
medium (flow rate across the nozzle apparatus and leakages
through labyrinth sealing) at pressure P0. In order to prevent
leakage through labyrinth sealing during measurements of flow
rate across the nozzle apparatus, a special device is used for direct
supply of working medium to the nozzle apparatus bypassing
sealing of gas static suspension and the torque measuring unit
while retaining pressure before the nozzle apparatus.
The layout of supply system and measuring instruments of the
experimental facility are illustrated in Fig. 7, overall view of the
facility in Fig. 8. The manual tap, the air filter 2, and the
manometer 3 are installed in inlet channel of the supply system.
The supply system is subdivided into 2 lines separated from the
inlet channel by the electropneumatic valves 4 and 5 which protect
the facility against accidental starts with deactivated control
system. The first main line is intended for air supply to gas static
suspension, and the second one to the experimental facility. The
second pipeline is equipped with the electropneumatic converter 6,
which controls the experiments, and with the instruments to
measure air flow rate and temperature. Therefore, the facility can
307
International Journal of Engineering & Technology
measure toque created by the nozzle apparatus, as well as
pressure, temperature, and flow rate of working medium.
Fig. 7: Schematic view of supply system and measuring instruments of
the facility:
1 manual tap; 2 –K4-10-50 manometer; 3EAF6000 filter; 4,5 –
pneumatic valve; 6 ITV3050-21F4N electropneumatic converter with
pressure indication; 7PF2A703H-F10-28N flow meter; 8 air inlet
collector to torque measuring unit; 9DS18B20 temperature sensor.
Fig. 8: Overall view of experimental facility
Integral parameters of the nozzle apparatus were predicted as
follows. The circumferential component of absolute velocity at
outlet from the nozzle apparatus  is determined by equation of
flow torque in the nozzle apparatus:
 =
 , (1)
where M is the torque measured on the experimental facility; 
is the external radius of the centrifugal nozzle apparatus (in the
experiment: Rext=44 mm); G is the gas mass flow rate.
The radial component of absolute velocity  at outlet from the
nozzle apparatus is determined by the continuity equation:
 =
, (2)
where G is the mass flow rate; F is the surface area of nozzles
determined by outlet cross sections of nozzles; is the real gas
density in outlet cross sections of nozzles.
Since the gas density at outlet from the nozzle apparatus in
actual process is unknown, then the additional interrelations
between the flow variables should be used for determination of
.
Let us consider the following method of determination of integral
parameters. Since the initial parameters of isentropic and actual
processes coincide, then the loss in nozzles can be determined as
follows:
2*
1 1 01
( ) (1 )( )
is p is p is
ii СT T С T T
ζψ
=−= − =
,
hence:
=  1 + (1
ψ
)
 1, (3)
where
ζ
is the energy loss during actual expansion in the
nozzle apparatus;
1
i
is the enthalpy in final cross section of the
nozzle apparatus upon actual expansion ;
is
i
is the enthalpy in
final cross section of the nozzle apparatus upon isentropic
expansion;
p
С
is the air mass isobar heat capacity;
1
T
is the
temperature in the end of actual air expansion in nozzles;
is
T
is
the temperature in the end of isentropic air expansion in nozzles;
ψ
is the velocity factor.
The temperature in the end of isentropic air expansion in nozzles
is determined by the equation of adiabatic expansion:
 =

where T0
* is the air braking temperature before the nozzle
apparatus; pa is the air ambient pressure; p0
* is the initial total air
pressure before the nozzle apparatus; k is the adiabatic exponent.
From the equation of state for gas parameters in the nozzle outlet
cross section, let us determine the gas density at outlet from the
nozzle apparatus:
= 

where R is the gas constant, for air: R=287 J/kg·K.
Then, with consideration for Eqs. (3), (4), and (5), Eq. (2) is
rewritten as follows:
 = 
 

1 + (1ψ)(
 1).
By definition the nozzle velocity factor is:
ψ =


.
Finally, we have a set of 2 equations, Eqs. (6) and (7), with 2
unknown variables: ψ and . The set is solved by iterations.
Knowing the velocity projections, it is possible to predict the
angle between the vector of flow outlet velocity and the tangential
line to operating wheel at the flow outlet point.
5. Results
Taking into consideration the design requirements in the first
experimental series, the following combinations of geometric
variables of operating wheel were used, see Table 1. Table 2
summarizes the main results of the first experimental series. The
surface area of flow cross section of the nozzle apparatus for
various operating wheels was from 13.98 to 15.41 mm2, the air
temperature: +23°C, the ambient pressure: 0.100 MPa`, the
pressure before the nozzle apparatus: 0.321 MPa.
Table 1: F/f and γ factors for the first experimental series
Point No.
Adopted absolute F/f
Adopted absolute γ
0
1.3
7
1
1.2
9
2
1.4
9
3
1.4
5
4
1.2
5
Table 2: Main results of the first experimental series
No.
Air flow
rate through
nozzle
apparatus
(G, l/min)
Nozzle
apparatus
torque
(M0, N·m)
Velocity
factor of
nozzle
apparatus
(
ψ
)
Flow
exit
angle
(γ,°)
Flow
coefficient
of nozzle
apparatus
(µ)
0
740
0.095
0.785
33.286
0.968
1
705
0.098
0.825
30.586
0.973
2
715
0.090
0.748
30.842
0.974
3
675
0.085
0.749
31.094
0.977
4
715
0.089
0.787
36.600
0.974
On the basis of the obtained results, the regression equation of the
first order was derived. The linear response function was adopted
in the first experimental series:
cfFba ++= )/()γ(ψ
,
International Journal of Engineering & Technology
308
since such form was required and sufficient for determination of
the function gradient. The obtained regression equation was as
follows:
ψ 0.01075 (γ) 0.03075 ( / ) 0.7818Ff= ⋅− ⋅ +
The gradient of response function based on the results of the first
experimental series is illustrated in Fig. 8. In the considered
domain of parameters it is possible to conclude that the velocity
factor depends more on the geometrical expansion extent than on
the geometrical expansion angle of supersonic nozzle of jet
reaction turbine.
For subsequent specification of optimum geometrical variables of
the nozzle apparatus, it is required to consider the combinations of
variable factors in accordance with direction of the
aforementioned gradient of the response function, see Fig. 9. With
consideration for design requirements in the second experimental
series, the combinations of geometrical variables of operating
wheels in Table 3 were adopted.
Fig. 9: Gradient of factors and experimental points
All experimental lines were positioned on the gradient line, each
subsequent point at higher distance from the reference point "0",
Fig. 9. Surface area of the flow cross section of the nozzle
appratus for various operating wheels was in the range from 14.56
to 15.01 mm2, the air temperature: +20°C, the atmospheric
pressure: 0.101 MPa, the pressure between the nozzle apparatus:
0.320 MPa. The main experimental results of the second series are
summarized in Table 4.
Table 3: F/f and γ for the second experimental series
Point No.
Adopted absolute F/f
Adopted absolute γ
5
1.27
10
6
1.26
12
7
1.25
14
8
1.23
16
Table 4: Main results of the second experimental series
No.
Air flow rate
through
nozzle
apparatus (G,
l/min)
Nozzle
apparatus
torque (M
0
N·m)
Velocity
factor of
nozzle
apparatus
(ψ)
Flow
exit
angle
(γ,°)
Flow
coefficient of
nozzle
apparatus (µ)
5
715
0.097
0.798
30.534
0.968
6
695
0.102
0.832
26.550
0.970
7
725
0.096
0.779
30.518
0.972
8
710
0.093
0.766
29.868
0.975
Velocity factor of the nozzle apparatus increased up to point 6 and
then decreased. Therefore, while moving along the gradient
direction, the maximum of target function was passed and the
optimum combination of the considered geometric variables of
nozzle apparatus was determined.
6. Conclusion
While analyzing experimental data, it should be mentioned that
the greatest influence on the nozzle efficiency is exerted by
geometrical expansion angle of supersonic nozzle of jet reaction
turbine γ, this is indicated by the coefficients of appropriate
variables in regression equation. The obtained results agree with
the data of other researchers [16, 17, 18, 19, 20, 21] and provide
additional information. Herewith, the experimental point 6
provides the greatest efficiency of pneumatic two-stage small-size
radial turbine. Optimum combination of nozzle variables of the
first jet reaction stage of the considered turbine was determined
experimentally:
γ = 12°, F/f = 1.26.
References
[1] Y.P. Kuznetsov, V.L. Khimich, S.N. Khrunkov, et al., Radial two-stage
microturbine for pneumatic actuation, Russian Aeronautics 59(2) (2016)
283-286.
[2] V.L. Khimich, A.B. Chuvakov, V.A. Kikeyev, et al., Two-rimming
radial turbine for drive of manual pneumatic grinders, International
Journal of Applied Engineering Research 11(16) (2016) 8982-8986.
[3] V.L. Khimich, A.B. Chuvakov, S.N. Khrunkov, Maximum rotation
frequency regulators of high-velocity small-sized pneumatic actuators,
International Journal of Applied Engineering Research 11(18) (2016)
9256-9260.
[4] V.L. Khimich, A.B. Chuvakov, S.N. Khrunkov, et al., The influence of
aerodynamic characteristics of the elements of the flow range of the
radial two-row range of the radial two-row microturbine on its dynamic
characteristics, International Journal of Applied Engineering Research
11(23) (2016) 11501.
[5] I.I. Kirillov, A.I. Kirillov, Teoriya turbomashin [Theory of
turbomachines], Mashinostroenie, Leningrad, 1974.
[6] A.S. Natalevich, Vozdushnye mikroturbiny [Air microturbines],
Mashinostroenie, Moscow, 1979.
[7] M.E. Deich, Tekhnicheskaya gazodinamika [Engineering gas
dynamics], Energiya, Moscow, 1974.
[8] A.Yu. Fershalov, M.Yu. Fershalov, Yu.Ya. Fershalov, et al., Results of
the study rotor wheels supersonic microturbines with a large angle of
rotation of the flow, Applied Mechanics and Materials 752-753 (2015)
884-889.
[9] Yu.Ya. Fershalov, M.Yu. Fershalov, A.Yu. Fershalov, Energy
efficiency of nozzles for axial microturbines, Procedia Engineering 206
(2017) 499-504.
[10] A.Yu. Fershalov, M.Yu. Fershalov, Yu.Ya. Fershalov, et al., Research
data of turbine nozzles of 5-9 degree outlet angles, Applied Mechanics
and Materials 770 (2015) 547-550.
[11] A.Yu. Fershalov, M.Yu. Fershalov, Yu.Ya. Fershalov, et al., The design
of the nozzle for the nozzle box microturbines, Applied Mechanics and
Materials 789-790 (2015) 203-206.
[12] Yu.Ya. Fershalov, T.V. Sazonov Experimental research of the nozzles,
Advanced Materials Research 915-916 (2014) 345-348.
[13] T.V. Sazonov, Y.Y. Fershalov, M.Y. Fershalov, et al., Experimental
installation for the study of nozzles microturbines, Applied Mechanics
and Materials 635-637 (2014) 155-158.
[14] D. Ibragimov, A. Mochalov, Yu. Ilinskiy, Research Data of
Microturbine Nozzles with Outlet Angles under 9 Degree (Conference
Paper), International Conference on Industrial Engineering, ICIE 2017;
Saint-Petersburg; Russian Federation; 16 May 2017 to 19 May 2017;
Procedia Engineering 206 (2017) 493-498
[15] Yu.P. Kuznetsov, A.B. Chuvakov, Eksperimental'naya ustanovka dlya
issledovaniya malorazmernykh turbinnykh stupenei [Experimental
facility for investigation into small-size turbine stages], Izvestiya
VUZov. Mashinostroenie, 4 (2013) 58-64.
[16] V.I. Korenbaum, A.A. Tagiltsev, A.E. Kostiv, et al., A low-frequency
power-type pressure-gradient receiver for oceanological investigations,
Instruments and Experimental Techniques 60 (2017) 5.
[17] Fershalov, Yu. Fershalov, M. Fershalov, et al., Constructive and regime
factors influence on turbine wheel characteristics with large rotation
flow angle of blades, Polyarnaya mekhanika 3 (2016) 976-985.
[18] A.Yu. Fershalov, Yu.Ya. Fershalov, L.P. Tsigankova, The degree of
influence of constructive and regime factors on the characteristics
turbine wheel steps shoulder who are more angles of rotation, RECENT
ADVANCES in MATHEMATICS, Series "Mathematics and
Computers in Science and Engineering Series”, WSEAS Press,
Budapest, 2015, 130-133.
[19] A.Y. Fershalov, Y.Y. Fershalov, M.Y. Fershalov, et al., Analysis and
optimization of efficiency rotor wheels microturbines, Applied
Mechanics and Materials 635-637 (2014) 76-79.
[20] M.Y. Fershalov, Y.Y. Fershalov, A.Y. Fershalov, et al., Microturbines
degree of reactivity, Applied Mechanics and Materials 635-637 (2014)
354-357.
[21] Yu.Ya. Fershalov, Technique for physical simulation of gasodynamic
processes in the turbomachine flow passages, Russian Aeronautics 55(4)
(2012) 424-429.
ResearchGate has not been able to resolve any citations for this publication.
Article
Technical solutions for the construction of a two-component power-type pressure-gradient receiver are developed. The manufactured prototype with dimensions of 111 × ∅52 mm provides an acousticpressure sensitivity in a plane wave of 60–70 μV/Pa at a frequency of 100 Hz. A mathematical model for an approximate calculation of the sensitivity to the acoustic pressure and optimizing the parameters of the structure was developed. The performance characteristics of the hydroacoustic pressure-gradient receivers, which provide oceanological investigations at frequencies that are substantially lower than 1 kHz, were improved.
Article
Within the one-dimensional strip theory of turbomachines, the authors performed the computational studies of the effect of flow range parameters of the two-row radial microturbine with a jet-reactive centrifugal stage and a centripetal speed stage developed at the NSTU. The main characteristics of the proposed two-row microturbine were obtained, including the dependencies of the inlet and outlet speeds of the microturbine stages, dependencies of the energy performance of the individual stages and the microturbine as a whole on the U/C0 characteristic ratio. The quantitative assessment of the influence of aerodynamic perfection of the individual elements of the microturbine flow range on its efficiency was obtained. It was revealed that at the speed rate of microturbine operation, at the value of the characteristic ratio of circumferential speed U to the theoretical gas flow rate C0, determined by the available heat drop, U/C0 = 0.15 while reducing the speed ratio from 0.9 to 0.8 for all the elements of a flow range, the reduction in the efficiency of the microturbine as a whole will be caused by the influence of aerodynamic perfection of jet-reactive centrifugal stage by approximately 60%, by the influence of aerodynamic perfection of intermediate adjustable vane by approximately 30%, and by the influence of aerodynamic perfection of centripetal speed stage by approximately 10%.
Article
The problems of the development of maximum rotation frequency regulators and their use as a part of high-speed small-sized pneumatic actuators were considered. It is noted that widely used at the present time maximum rotation frequency regulators with mechanical frequency sensor are not sufficiently reliable at high rotation frequencies due to the presence of mutually moving elements. The authors developed a fundamentally new constructive scheme of maximum rotation frequency regulators, containing the elastic ring, which combines the functions of executive and sensitive elements. Regulators can be installed in the input and in the output section of the energy module of the pneumatic actuator. It is noted that maximum rotation frequency regulators installed in the output section can be used in conjunction with any known types of the energy module of pneumatic actuator. A structural scheme of the regulator for relatively low-speed machines, which implements the longitudinal deformation of the elastic ring, was proposed. The developed maximum rotation frequency regulators showed good sensitivity, reliability, performance and energy efficiency. The created regulators can be used in a wide range of operating parameters of pneumatic actuators.
Article
An innovative kinematic scheme of pneumatic turbine drive was proposed and the use of two-row centrifugal-centripetal turbine stage was justified. We proved the feasibility of the proposed kinematic scheme of the turbine drive in a variety of aircraft components by an example of the manual pneumatic grinding machine.
Article
The problem of the use of a turbine drive in the manual pneumatic grinders was considered. The substantiation of the use of turbines with two velocity stages in grindinders was provided. A fundamentally new design scheme of centrifugal centripetal turbine with two velocity stages was proposed, the features of the technology of manufacturing its components were described. The advantages of the developed constructive scheme compared to traditionally used two-stage axial turbines were substantiated. The modern methods of numerical simulation and visualization of aerodynamic processes implemented in ANSYS software complex were used in order to improve the nozzle unit channel. Comparative experiments have shown the advantages of the developed grinder compared with the machine of one of the world's leading manufacturers of pneumatic tools – Air Turbine Tools company (USA). The conclusion was made about good prospects and high competitiveness of the developed grinder.
Article
This paper presents the a mathematical regression model for the reactivity degree of microturbine stages depending on the constructed and model factors that have the greatest impact on the function value.
Article
Describes the experimental setup for studying the nozzles. Presents a methodology of the experiment and data processing of the results.
Article
Examined efficiency of axial rotor wheels microturbines. The mathematical models, regression-type, for efficiency rotor wheels and the exit angle of the working body from rotor wheels are presented. The technique of determining the gas-dynamic and structural characteristics of the flow part of the rotor wheels microturbines are also shown.
Article
The paper presents a comparative analysis of existing designs nozzle turbines. The advantages and disadvantages of existing designs nozzles. The description of the new nozzle design for axial microturbines. The analysis of the reasons for reducing the loss of kinetic energy of the flow of the working fluid in the nozzles of the proposed design offers.
Article
The article presents experimental data of microturbines nozzle boxes research. It describes mathematical models of nozzle outlet gas angle. Research results are analyzed and recommendations on design of nozzle boxes with small constructive outlet gas angle are given.