Analysis of Efficiency of Full-submerged Archimedes Screws of

Rotary-screw Propulsion Units of Snow and Swamp-going

Amphibious Vehicles

Svetlana Karaseva

1a

, Vladimir Belyakov

1b

, Vladimir Makarov

1c

and Dmitry Malahov

2d

1

Nizhny Novgorod State Technical University n.a. R.E. Alekseev, Minin Str., 24, Nizhny Novgorod, Russian Federation

2

Moscow Automobile and Road Construction State Technical University, Leningradsky prospect, 64,

Moscow, Russian Federation

Keywords: Rotary-screw Propulsion Unit, Full-submerged Archimedes Screw, Propulsive Characteristics, Snow and

Swamp-going Amphibia, Geometrical Parameters of Archimedes Screw, Performance Curves, Overwater

Characteristics, Computer Simulation.

Abstract: The paper presents results of the numerical analysis of propulsive characteristics of full-submerged

Archimedes screws of rotary-screw propulsion units of snow and swamp-going amphibious vehicles with the

most typical geometric characteristics for this class of vehicles. The received performance curves and the

pictures of visualization of interaction between water environment and Archimedes screws with different

helix angles are given. The maximum available values of efficiency determinants of Archimedes screws for

cruising and mooring modes are determined. The results of comparative analysis of efficiency of Archimedes

screws and propellers with the same operation conditions are considered. The ways to increase the efficiency

of rotary-screw propulsion units of snow and swamp-going amphibious vehicles according to the results

received are designated. The results and the conclusions obtained as part of the study could be used by

developers of amphibian with rotary-screw propulsion units to estimate and provide the overwater

characteristics.

1 INTRODUCTION

The traditional designing of water propulsion units in

shipbuilding intends the realization of specific

procedure, the main part of which is to determine the

geometrical parameters of the working body of water

propulsor with the help of performance curves of

systematical series based on results of tests in

hydrodynamic laboratories. For example, when

designing the amphibia moving afloat by the medium

of propellers the performance curves of public Troost

or Kaplan series got by shipbuilders are usually used.

The developers of amphibian vehicles with rotary-

screw propulsion units (RSP) havenβt got such

possibility. This is due to the mild interest of

shipbuilders in rotary-screw propulsors (because of

a

https://orcid.org/0000-0002-1666-777X

b

https://orcid.org/0000-0003-0203-9403

c

https://orcid.org/0000-0002-4423-5042

d

https://orcid.org/0000-0002-5706-9557

their low propulsive characteristics in comparison

with propellers) and the lack of attention of

developers and researches of amphibian with RSP to

vehicle overwater characteristics. Among the last one

it is definitely necessary to point the experimental

works of Cole (1961) and theoretical studies of Sogin

and Shapkin (2006); however, they did not conduct

full systematic studies of the RSP hydrodynamics.

2 COMPUTER SIMULATION OF

PROPELLER

To get the full relevant view of afloat performance of

the rotary-screw propulsor it is essential to perform

the enough amount of physical or simulation

438

Karaseva, S., Belyakov, V., Makarov, V. and Malahov, D.

Analysis of Efο¬ciency of Full-submerged Archimedes Screws of Rotary-screw Propulsion Units of Snow and Swamp-going Amphibious Vehicles.

DOI: 10.5220/0011096700003191

In Proceedings of the 8th International Conference on Vehicle Technology and Intelligent Transport Systems (VEHITS 2022), pages 438-444

ISBN: 978-989-758-573-9; ISSN: 2184-495X

Copyright

c

ξ 2022 by SCITEPRESS β Science and Technology Publications, Lda. All rights reserved

experiments with different input parameters and wide

range of values of them, meanwhile the results of

computer simulation demand the verification more

than other one. Further it is planned to create the stand

to get the verification data based on the results of

physical model tests of Archimedes screws, but at this

stage of research it was decided to use computer

simulation for preliminary estimation. To estimate the

adequacy and accuracy of the results obtained it

would be a good idea to compare them with the data

of Cole research but he used too small physical model

in his experiments which always leads to inevitable

impact of scale effects, moreover, the water tests were

performed in mooring mode only, and the small

dimensions of test basin relatively to the model of

Archimedes screw led to presence of reverse flows

which skewed the results of experiment (Shapkin,

2017). Cause of this the computer model was

processed and tested on Troost series propeller with

close topology and similar performance conditions

(Figure 1).

For verification the five-blade propeller with

maximum disk-area ratio of series was selected to

provide the adequate comparison. Such selection is

defined by the specificity of design of rotary-screw

propulsion unit which has rather high disk-area ratio,

in other words, the ratio of an expanded area πΉ

ξ―ξ―

of all

elements of blade system to area of circle with

diameter equal to propeller diameter:

πξ΅

4π§ β πΉ

ξ―ξ―

πβπ·

ξ¬Ά

(1

)

Propeller parameters are given in the Table 1.

Here pitch ratio is the ratio of propeller pitch β the

distance traveled by propeller in one full revolution in

translational direction β to propeller diameter; hub

ratio is the ratio of hub diameter to propeller diameter

(Basin, 1977).

Figure 2 shows performance curves conforming

to the propeller selected (Bernitsas, 1981). The

diagrams show the correspondences of non-

dimensional coefficients built in relative coordinates.

Figure 1: Propeller B 5.105.1.4 (the visualization pattern of computer simulation: v=4 m/sec, n=500 rpm).

Table 1: Propeller parameters.

Parameter

Designation

Value

Diameter, mm

D

800

Blade number, pcs

z

5

Pitch ratio

H/D

1.4

Hub ratio

d/D

0.325

Disk-area ratio

ΞΈ

1.05

Analysis of Efο¬ciency of Full-submerged Archimedes Screws of Rotary-screw Propulsion Units of Snow and Swamp-going Amphibious

Vehicles

439

Thrust coefficient:

πΎ

ξ―

ξ΅

π

π

βπ

ξ¬Ά

βπ·

ξ¬Έ

(2)

Torque coefficient:

πΎ

ξ―

ξ΅

π

π

βπ

ξ¬Ά

βπ·

ξ¬Ή

(3)

Propulsive coefficient (efficiency):

π

ξ¬΄

ξ΅

π½

2π

β

πΎ

ξ―

πΎ

ξ―

(4)

Advance ratio:

π½ξ΅

π£

ξ―

πβπ·

(5)

In the above formulas π ξ΅ 1000 ππ/π

ξ¬·

is water

density, π is propeller thrust (N), π is torque of

propeller shaft (Nβ’m), π is propeller rotational speed

(rpm) and π£

ξ―

is speed of water flow (m/sec).

Performance curves essentially characterize the

performance of the particular propeller moving with

the particular rotation speed. For all geometrically

similar propellers their hydrodynamical

characteristics shown in such correspondences are

identical. The advance ratio characterizing the

performance mode uniquely determines thrust and

torque coefficients. The correspondence of

propulsive coefficient becomes equal to zero in two

end points: in the first instance there is no speed, in

the second β no thrust; the function runs up to

extremum with specific correlation of all data which

forms the range of recommended values of

parameters for even particular propeller

(https://studwood.ru, 2022/01/17).

As a result of computer simulation there were

procured the correspondences of thrust and torque of

propeller in open water when the flow speed is 4

m/sec in the range of rotation speed from 200 to 600

rpm. The diagrams (figure 3) show that the maximum

divergence of values of thrust and torque got during

physical and computer modelling is not more than 5

and 2 percent respectively. Such inaccuracy is

thoroughly acceptable for comparative analysis.

3 COMPUTER SIMULATION OF

ROTARY-SCREW

PROPULSION UNITS

Parameters of RSP modelled were determined

according to the results of analysis of existing snow

and swamp-going amphibious vehicles (Kolotilin,

2015; Danilov, 2011; Kulyashov and Kolotilin, 1993;

Nikolaev and Kulyashov, 1973).

The comparative estimation of geometrical

parameters showed that their values for the most part

of amphibian are in the particular ranges (table 2).

One of the main factors determining the dynamical

characteristics of RSP in afloat motion is the helix

angle of Archimedes screw Ο. This parameter

essentially effects on thrust and torque of propulsor

Figure 2: Performance curves of the propeller.

VEHITS 2022 - 8th International Conference on Vehicle Technology and Intelligent Transport Systems

440

Π°

)

Pro

p

eller tor

q

ue

b

)

Pro

p

eller thrust

Figure 3: Comparison of the results of computer simulation and the results of model testing of propeller in test basin.

Table 2: Value ranges of geometrical parameters of RSP.

Parameter

Designation

Value

Diameter, mm

D

600...1000

Blade number, pcs

z

1...3

Pitch ratio

H/D

1.46...2.83

Hub ratio

d/D

0.7...0.9

Disk-area ratio

ΞΈ

1.2...2.5

Helix angle, Β° Ο 24...42

Table 3: Geometrical parameters of Archimedes screw models researched.

Parameter

Model β1

Model β2 Model β3

D

800

800 800

z

3

3 3

H/D

1.4

1.8 2.5

d/D

0.8

0.8 0.8

ΞΈ

3.48

2.91 2.35

Ο 24 30 39

and when the angular speed is permanent these

characteristics grow while angle Ο increases. For the

preliminary estimation of RSP efficiency in afloat

motion in full-submerged mode three models with

end and middle values of angle Ο were created (table

3).

Besides the evident, geometrical, parameters

impacting on the hydrodynamical characteristics of

propulsor the other factors should be noted,

specifically the performance peculiarities of rotary-

screw propulsion units of snow and swamp-going

amphibious vehicles in afloat motion essentially

determining the efficiency of RSP water moving

(Karaseva, 2021). These include the performance of

Archimedes screws of the most part of amphibian in

semi-submerged mode, the interaction between RSP

Archimedes screws and amphibia hull and the joint

action of Archimedes screws of amphibious vehicles

with tandem RSP as the most widespread design. At

this stage the aim was to simulate the performance of

single RSP apart from the vehicle in full-submerged

mode; however, in further research for development

of the calculation procedure of optimal parameters of

rotary-screw propulsion units while afloat

performance it is necessary to take into account all

factors.

Analysis of Efο¬ciency of Full-submerged Archimedes Screws of Rotary-screw Propulsion Units of Snow and Swamp-going Amphibious

Vehicles

441

Computer simulation for variations of Archimedes

screw design considered was done for travelling mode

(π£ξ΅4 π/π ππ, π ξ΅ 200 β¦ 1000 πππ) and mooring

mode (π ξ΅ 200 β¦ 600 πππ).

As a result, the large data set was got. Some

visualization patterns of the computer simulation

results are shown in the Figure 4.

Π°) Helix angle Ο=24Β°

b) Helix angle Ο=30Β°

c) Helix angle Ο=39Β°

Figure 4: Visualization patterns of computer simulation of hydrodynamics of full-submerged Archimedes screw of RSP (v=4

m/sec, n=500 rpm).

VEHITS 2022 - 8th International Conference on Vehicle Technology and Intelligent Transport Systems

442

4 COMPARATIVE ANALYSIS

Figure 5 gives the performance curves of three

variations of rotary-screw propulsors and of propeller

of Troost series in relative coordinates got as a result

of computer simulation. The analysis of curves

received shows that in travelling mode in the range of

values of advance ratio simulated Archimedes screws

with geometrical parameters peculiar to RSP of snow

and swamp-going amphibian have the maximum

efficiency values range from 0.16 to 0.22 growing

while increasing of helix pitch (increasing of helix

angle Ο). In the mooring mode the efficiency of using

of input power is usually characterized by relative

quality coefficient (Vasilβev, 2006)

π

ο±

ξ΅

π

1,16

οΊ

ππ·

ο»

ξ¬Ά/ξ¬·

(6)

Here π is shaft power (kW), and π

ο±

lies in the

range 0.31β¦0.38. The model with helix angle 30

degrees has the maximum efficiency in all range of

rotational speeds.

Therefore, the limiting efficiency of Archimedes

screws is essentially inferior to the same of propellers

in open water; efficiency of the last ones in the range

covered can reach 0.7 and relative quality coefficient

lies in the range 0.86β¦0.98. Comparably low

efficiency of Archimedes screws is determined

foremost by the presence of massive hub which

resistance is essentially grows with increase of both

movement speed and rotation speed. One more factor

reducing efficiency is the nonuniformity of the

distribution of thrust forces along the helixes of

Archimedes screws graphically illustrated by the

patterns of dynamical pressures shown in the

Figure 4.

Π°

)

Thrust coefficient

b

)

Tor

q

ue coefficient

c) Efficienc

y

d

) Relative quality coefficient

Figure 5: Characteristics of propeller and rotary-screw propulsion units.

Analysis of Efο¬ciency of Full-submerged Archimedes Screws of Rotary-screw Propulsion Units of Snow and Swamp-going Amphibious

Vehicles

443

When designing of rotary-screw propulsion units

of snow and swamp-going amphibious vehicles it

should be considered that:

1. The efficiency of using of input power for full-

submerged Archimedes screws of RSP in

mooring mode and in typical range of moving

modes is one-third of that of propellers with the

same diameter.

2. The maximum efficiency of RSP Archimedes

screws in travelling modes realises in the

advance ratio range 0.6β¦1.0 (the higher values

conforming to better overwater characteristics

correspond to larger helix angles). When

advance ratio is less than 0.5 Archimedes screws

have non-typical for propellers reduction of

thrust coefficient because of increasing of

resistance of massive hub during growing of

induced velocities.

3. The area of induced velocities along the

Archimedes screw (according to the result of

analysis of visualization patterns) which are 10

and more percent greater than velocity of

approaching flow has diameter equal to

1.1β¦1.2 diameters of Archimedes screw. To

reduce negative effects of interaction between

Archimedes screw and amphibia hull it is

necessary to locate Archimedes screws of RSP

at the appropriate distance from the hull.

5 CONCLUSIONS

Archimedes screws of existent RSP perform in

complex interaction with hull and appendages of

amphibia and between each other, moreover, the

semi-submerged mode is peculiar to snow and

swamp-going amphibious vehicles. The aspects

pointed require special research, nevertheless, the

performance curves of Archimedes screws in open

water received allow to determine the maximum

speed of afloat motion in the early stages of designing

when engine power and geometrical parameters of

Archimedes screws are set by land performance

conditions, and to correct these characteristics to

improve overwater performance.

ACKNOWLEDGEMENTS

The results of the given study have been obtained

with financial support of the grants of the President of

the Russian Federation β MK-336.2022.4.

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