Literature review

The experiment research of high-pressure air blowing ballast tanks

Liu Ruijie,Xiao Changrun,Liu Yihan

Naval University of Engineering,Wuhan 430033,China

Naval University of Engineering,Wuhan 430033,China

PetroChina Oil and Gas Pipeline Control Center,Beijing 100007,China

[email protected]

[email protected]

[email protected]

Key words: submarine self-propelled model;CFD;ballast tanks;high-pressure gas

Abstract.In order to test and verify the accuracy and reasonable of the mathematical model of the

high-pressure air blowing the main ballast tanks, the paper design a submarine self-propelled model

with the system of high-pressure air blowing the ballast tanks.Through the experiment without

propulsion, the paper obtains drainage performance and key performance parameters of

motion.Through the comparing of CFD, the result shows the ability to describe correctly the process

of high-pressure air blowing ballast tanks.

The submarine is one of most important strategic weapons. As it walks under water , it is easily

damaged. But there are many methods to take on emergency salvage action,like abandoning

ballast ,adjusting the water warehouse to get balance,manipulating rudders to get buoyancy and

adjustment of velocities. But the high pressure gas afford buoyancy and moment by removing water

of main tanks must be carried on when the cabins flooded , great diving angles , damage of pressure

tanks . And on the other hand ,it is required to take the action of removing water of main by high

pressure gas tanks when the submarine comes up to avoid mines or any other attack. In a extreme

situation , the submarine sits in the seabed , the high pressure gas afford buoyancy and moment by

removing water of main tanks acts as the crucial role.

This article focus on the high pressure gas . And we built a submarine self-propelled model to

carry on the experiment. Through the experiment we analyses the related factors of depth , time ,

heading angle , angle of trim and heeling angle.

The submarine self-propelled model with the high pressure gas.

There are two ways to study the movement of the submarine . One is through the full-scale ships.

The other is through submarine self-propelled model. Although dimensions of the submarine

self-propelled model certainly limits the accuracy , the submarine self-propelled model is still the

best replacement of full-scale trial of submarine. In fig.1 below , how the primary equipments is

arranged is showed . In the middle of the submarine model , there are 5 rectangles. They are the

water ballast tanks we mainly introduced in the article.

Fig.1 Construction of the Submarine Self-propelled Model

Applied Mechanics and Materials Vols. 411-414 (2013) pp 3010-3015 Online available since 2013/Sep/03 at www.scientific.net © (2013) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/AMM.411-414.3010

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bbbb RTmVp =

1.1 Coordinate system and the basic space motion equation of the submarine

The blow picture shows the coordinate system built for this text for convenience.E-εηζ is the

earth coordinate system and G-xyz is the coordinate system fixed on the submarine self-propelled

model.X , Y, Z in the photograph are the forces along the direction of x, y, z. And K, M, N are the

moment along the direction of x, y, z. ]1[

Fig.2 Fixed Coordinate System and Moving Coordinate System

Submarine emergence surfacing motion is a high mobility and shows nonlinear . Horizontal

movement is strongly coupling with planar motion, and it leads to trimm angle and heeling angle.

So six-degree-of-freedom motion equation must be used in the research. U.S. Navy Ships Taylor

Research and Development Center discovered a six-degree-of-freedom space motion equation. The

equation can be the basic motion equation here. But the equation will not detailed described here for

sake of article's length.

1.2 The model with high pressure gas ]2[

When happens to submarine emergency floating maneuverability , high-pressure gas is from the

high pressure cylinder. And it goes into water ballast tanks. Because of the high pressure and fast

speed of gas here , we consider the mixture of water and gas as a isothermal process. And because

heat exchanging process is quite slow , we consider the process as a adiabatic process. At the first

20~30s, pressure and temperature are unchanged , so it is a adiabatic expansion process. Compared

to the volume of water ballast tank , we think that the pressure of the high pressure cylinders is

never changed . In the picture below , c p

is the pressure of the high pressure cylinder; c T

is the

temperature of the gas in the high pressure cylinder; b p

is the pressure of gas in the water ballast

tanks; b V

is the volume of the water ballast tanks; b T

is the temperature of the gas in the water ballast

tanks; s A

is the area of water outlet; s v

is the drainage speed.

Fig.3 Structure Model with High-pressure Gas

1.3 Description of experiment

We created the submarine self-propelled model according to a submarine. And we did the

experiment in a lake about 25m deep. In order to get a brief overview , we took notes of the

relationship with pressure . We did the experiment at different depths . And we recorded attitude.

Applied Mechanics and Materials Vols. 411-414 3011

) )(2

(B ∑∑∑ −

=== ••

i

wbi Hibi

i

bi

i

pp ACq

iB ρ

shb ACq

s v=

ρ )(2

wb s

pp v

− =

))()(( 1

2 12

k

k

F

bk

F

b FF

P

P

P

P

k

k PAC

Fm +•

− −

•= ρ

1

1 1

) 1

2 ( −

+•

+ = k

k

F

P

k k

RT

CA

F Fm

b

b bb

b

b

V

dt

dV pRT

dt

dm

dt

dp −

=

We did the some simulation by CFD software. The results correspond well.

Fig.4 Picture of Experiment

2 Mathmatical Model of Blow

2.1 Generation of buoyancy force

This process produces great buoyancy force for the whole submarine self-propelled model. And

the magnitude of force can be expressed by volume of water expelled from the water ballast tanks.

But the speed of water expelled from the water ballast tanks changes according to the pressure of

the water ballast tanks and outside. So we can calculate the s v

.

(1)

w p

is the instantaneous environmental pressure; ρ

is the density of sea water.

(2)

b q

is the quantity of flow; h C

is the loss factor , and h C

=0.7 in this article.

(3)

B •

is the change rate of frequency ; i is the quantity of water ballast tanks.

1.2.2 Pressure of the water ballast tanks

(4)

b m

is the weight of gas in the water ballast tanks;R is a constant number,R=287.1 J/(kg•K); b T

is a constant.

Derivation of (4) is blow:

(5)

2.2 Gas flow released from the high pressure cylinder

1) Early stage of release

(6)

Fm •

is gas flow released from cylinder; 1 A

is the area of nozzle;C is the tank value; k=1.4

2) Middle stage

At this stage ,

1

k

1

2 (1 −

+ ≥≥ k

F

b

kP

P ） and pressure decreases .

(7)

3012 Information Technology Applications in Industry II

0

1

0

0

0

)(, F

k

F

F FF

k

F

F F

T m

m TP

m

m P •=•



   

 = −

3) Last stage

Gas is out of the high pressure cylinder , so Fb PP =

.

(8)

0F m

is the initial quantity of gas in the cylinder ; 0F P

is the initial pressure in the cylinder; 0F T

is the initial temperature.

3 Examination Result and Analysis

3.1 Depthkeeping and zero speed

In fig.5 , it shows us the relationship between depth and time . The exact data is recorded in the

form 1. The pressure of the high pressure cylinder is always two atmos compared to the volume of

water in the tanks. It is easy to see that it spends more time at deeper depth. But fig.5 shows the

nonlinearity. The ratio between depth and time is not nonlinear. It is because the deeper the depth

is ,the pressure is so the slower the drainage speed is .

Fig.5 The Rise Time under Different Depth

3.2 Depthkeeping and main ballast tank blowing

The experiment is carried out at 4m depth. The biggest water ballast tank blew and other four

smaller tanks without any action. The main ballast tanks is about 30L. Propeller is fixed. Depth ,

trim , heel and heading angle is recorded in fig. 6.

Fig.6 Experiment Data with Main Ballast Tank Blowing

From the fig.6 , we can see that the submarine self-propelled model lifted its stern when it began

to blow but heading angle is not very big. After about 50s, the model went up quickly and the

heading angle began to change fast. The model rose to the surface with the biggest heading angle at

about 82s. Heel is small at the process.

3.3 Depthkeeping and three tanks blowing

4L and 2L tanks at the head of model and the best 30L tank blew in this process at 4m

depth.Propeller is fixed . Depth , trim , heel and heading angle is recorded in fig.7.

Through the analysis of the process,we can get the following conclusion. After about 45s ,trim ,

heel and heading angle are stable . Trim angle is bigger than fig.7 but heading angle is much

smaller . Heel angle is still very small , but it is a little bigger . This is because there are more tanks

blowing and when the gas went into the water tanks , it will leads to nondirectional rock. And the

time to get to the surface is much sooner , about 25s earlier.

Applied Mechanics and Materials Vols. 411-414 3013

Fig.7 Experiment Data with Three Tanks Blowing

3.4 Simulation with CFD

We did some simulations with CFD softwares. To simplify the simulation, we only built a cuboid

according to the shape of the main water ballast tank to simulate submarine self-propelled model's

motor process. We can see from the results that CFD results fit well with experiment data. So

simulation has good accuracy. We simulate the time for water ballast tank to drain emptily.And here

the paper show the change of pressure distribution. The depth of cuboid simulated was 1m , 2.9m

and 4.3m. The time simulated is blow 8% difference.

Table. 1 Time to drain

Depth/m

Time/s

Experiment

data

Simulation

data

1.09 220 209

2.88 273 251

4.3 475 498

Fig.8 Phase Diagram of Pressure Changing

4 Conclusion

On the basis of our experimental condition , we discussed the system of submarine high-pressure

air blowing main ballast tanks . We built a submarine self-propelled model to study . Law of motion

from static condition without propulsion is discuss in the article. But the system of air blowing main

ballast tanks is mainly used at the volley. So we will discuss the system with propulsion later.

The simulation in this paper is only about main water ballast tank. It ignored the interaction

between the model shape and water, and also the influence of rudders. Further study of simulation

will do with full-scale model.

3014 Information Technology Applications in Industry II

References:

[1] Shi Shengda.Submarine Maneuverability[M].Beijing:National Defence Industry Press,1995.In

Chinese.

[2] Chen Sheng-chun , Liu Hui ,Li Qi-xin. Reseratch on submarine emergency floating

maneuverability with flooded compartment . Ship and Ocean engineering,2012,41(4):168-171.In

Chinese.

[3] Li Qi-xiu , Liu Hui , Wu Xiang-jun. The simulation research of high pressure air blowing the

main ballast tank based on CFD.Ship Science and Technology,2012,34(9):56-60.In Chinese.

Applied Mechanics and Materials Vols. 411-414 3015

Information Technology Applications in Industry II 10.4028/www.scientific.net/AMM.411-414 The Experiment Research of High-Pressure Air Blowing Ballast Tanks 10.4028/www.scientific.net/AMM.411-414.3010

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