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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.
8th International Conference TUNNEL SAFETY AND VENTILATION
- New Developments in Tunnel Safety-
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
8th International Conference TUNNEL SAFETY AND VENTILATION
- New Developments in Tunnel Safety-
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
8th International Conference TUNNEL SAFETY AND VENTILATION
- New Developments in Tunnel Safety-
Frequency
convertor
Electric batteryImpellor
Layout and design of setup
up for model experiments
PHYSICAL SIMULATION
Test installation
4
8th International Conference TUNNEL SAFETY AND VENTILATION
- New Developments in Tunnel Safety-
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.
8th International Conference TUNNEL SAFETY AND VENTILATION
- New Developments in Tunnel Safety-
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
8th International Conference TUNNEL SAFETY AND VENTILATION
- New Developments in Tunnel Safety-
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
8th International Conference TUNNEL SAFETY AND VENTILATION
- New Developments in Tunnel Safety-
MATHEMATICAL SIMULATION
Simulation model
Finite element grid
Boundary condition
8
8th International Conference TUNNEL SAFETY AND VENTILATION
- New Developments in Tunnel Safety-
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
8th International Conference TUNNEL SAFETY AND VENTILATION
- New Developments in Tunnel Safety-
RESULTS OF MATHEMATICAL SIMULATION
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
8th International Conference TUNNEL SAFETY AND VENTILATION
- New Developments in Tunnel Safety-
RESULTS OF MATHEMATICAL SIMULATION
With take account nature draft
11
8th International Conference TUNNEL SAFETY AND VENTILATION
- New Developments in Tunnel Safety-
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
8th International Conference TUNNEL SAFETY AND VENTILATION
- New Developments in Tunnel Safety-
13
Thank you very much for attention
8th International Conference TUNNEL SAFETY AND VENTILATION
- New Developments in Tunnel Safety-
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]