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8th International Conference TUNNEL SAFETY AND VENTILATION

- New Developments in Tunnel Safety-

Open joint-stock company

“Lenmetrogiprotrans”St. Petersburg State

Mining University

USE OF VENTURI JETS LOCATED OUT OF TUNNELS

FOR THEIR VENTILATION DURING THE PERIODS OF

TUNNELING COMPLETION OR AT THEIR

RECONSTRUCTION

Gendler S. G., Savenkov E. A.

Russia

Graz, April 2016

LET ME GIVE YOU SOME BACKGROUND

In Russia safety norms prohibited to

use only the nature draft for

ventilation during of the tunnel

driving. In this connection in the

tunnel is being built barricade, in

which installed fan for ventilation

tunnel. Application of its ventilation

schemes does not seem rational as it

decreases mobility of the mining and

construction equipment.



Four years ago after 6th

International Conference in Graz

during in technical visit we

witnessed the fire test. Fan

located at some distance from

tunnel portal has been used for its

ventilation

2



The main objective of researches consisted in justification of a possibility of venturi

jet use when tunnel driving is completed and through-flow ventilation is introduced.

Task - to establish a functional relationship between the venturi jet performance

curves and air velocity in the tunnels.

Methods of investigation - physical and mathematical sumulation of aerodynamic

processes in tunnels with a venturi jet used as the draught source.

Layout of venturi jet in front of tunnel portal

Free jet edge

Fan Portal section Сross-section

projection of jet

Lloc

3



Frequency

convertor

Electric batteryImpellor

Layout and design of setup

up for model experiments

PHYSICAL SIMULATION

Test installation

4



Installation of flap in the tunnel model

Tunnel section without and with flag

Full aerodynamic drag factor of the model

Where local drag factor of the flap

5

- internal diameter of the fan hole (df)

- output air velocity (Vf),

- tunnel length (𝑳𝑻), - distance from the venturi jet location to the portal (Lloc),

- hydraulic diameter of the tunnel (Dт),

- air density (ρa);

- full aerodynamic drag factor of the tunnel (ζ Т): 𝜻𝑻 = (𝟏 + 𝝃𝒆𝒙𝒕 + 𝝀𝑻𝑳𝑻

𝑫𝑻) , 𝝀𝑻 is

the friction factor; ξext is the local drag coefficient of the tunnel intake section.



Factors that affect the air velocity in the tunnel (Uт)

Similarity criteria

𝒁𝟏 =𝟖

𝝅𝟐𝜻𝑻

𝒅𝒇𝟒

𝑫𝑻𝟒; Z2= Dт/df; Z3 = Lloc./df

Air velocity in the tunnel UT/vf

𝑼т/𝑽𝒇 = 𝑭 𝒁𝟏𝒙 ∙ 𝒁𝟐

𝒎 ∙ 𝒁𝟑𝒏

6



RESULTS OF PHYSICAL SIMULATION

0,05

0,10

0,15

0,20

0,25

0,30

0 5 10 15 20 25

Uт/vв

Y=Z11,1×Z2

3,7×Z30,6

3,00

3,50

4,00

4,50

5,00

5,50

6,00

6,50

7,00

0 20 40 60

Av

erag

e ai

r v

elo

city

in

mo

del

of

tun

nel

,m

/s

Distance between the fan and portal, cm

Lт=1,5 m, df=27 mm, Vf=27,7 m/s.

26,0

3

63,1

2

48,0

131,0/ ZZZVU fТ

7



MATHEMATICAL SIMULATION

Simulation model

Finite element grid

Boundary condition

8



RESULTS OF MATHEMATICAL SIMULATION

parameter Lfun, м Lloc, m Dfan, m Vfan, m/sHnatural draft,

Pa

numerical

value10; 25; 40

150; 320; 740; 1100;

2730

1,0;

1,6

35,6;

32,80; 10; 20

Recycling zone

9




0,05

0,10

0,15

0,20

0,25

0,30

0 2 4 6 8 10 12 14 16 18

U/vf

Y =Z11,0×Z2

4,3×Z30,1

Their correlation with the physical modelling data (Slide 7) shows

that the discrepancy does not exceed 15%.10

0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,0 1,0 2,0 3,0 4,0

U/Vf

Y=Z11,0×Z2

4,3×Z30,1×Z4

0,5

U/Vf =0,087 ·Z1-0,93 ·Z2

-4,0 ·Z3 -0,09 ·Z4

-0,47

Where Z4= hn.d./ρa·Vf2




With take account nature draft

11



U= 0,5 m/s

U=1,5 m/s

U=2,5 m/s

0

1

2

3

4

5

6

10 30 50 70 90

U, m/s

hn.d., Pа

Y1 (500м)

Y2 (1000м)

Y3 (2000м)

Practical application of research results

Determination of the natural draft critical values , in which the tunnel is not

provided desired ventilation mode (Y1, Y2, Y3 – length tunnel)

Nature draft is directed opposite of direction action free jet

12

- The performed complex theoretical and experimental studies justified

the possibility to use venturi jets located at the tunnel portal as the

draught source for tunnel ventilation during construction and assembly

operations provided a through air flow is present.

- The obtained dependences render it possible to determine the

aerodynamic parameters and rational location of the venturi jets with

reference to the tunnel portals.

CONCLUSIONS



13

Thank you very much for attention



Gendler S. G., Full professor, Doct. Eng., professor of department

Industrial Safety. Saint-Petersburg Mining University

E-mail: [email protected]

Savenkov E. A.,Team manager Department of sanitary engineering and

ventilation, Open Joint Company Scientific Research, Design and

Surveying Institute “Lenmetrogiprotrans”

E-mail: [email protected]

mailto:[email protected]

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