Witt&Sohn AG Aug-11
Banana JetBanana Jet ®®The Revolution in Jet Fan Design
BananaBanana JetJet ®®
The Revolution in Jet Fan Design
Witt&Sohn AG Aug-11Banana Jet ®
Basic Jet fan principle
� Air flow forced by:� shock impulse of the jet fan airstream
� Relation of� thrust T (jet fans)
and� pressure Dp (axial fans)
Witt&Sohn AG Aug-11Banana Jet ®
Basic laws of physics in tunnels
� A short explanation:
c
ζζζζin ζζζζoutζζζζfriction
zzzzpiston
tunneltotalgrosrequiredtotal
dyn
winddynoutpistonfrictionintotal
ApT
AQ
cp
ppp
⋅∆=
⋅=⋅=∆
∆+∆⋅+++=∆
,,
22
22with
)(
ρρ
ζζζζ
DDDDpwind
Witt&Sohn AG Aug-11Banana Jet ®
Losses by tunnel design – Wall effect
� Impulse loss - “Wall effect” (Kempf)� Distance of fan axis to one boundary
Thrust, still air
Thrust, incl. losses
Losses
Traditional Jet
~9% losses
Traditional JetTraditional Jet
~13% losses ~15% losses
5.1DZ = 0.1
DZ = 7.0
DZ =
Z
D
Witt&Sohn AG Aug-11Banana Jet ®
Losses by tunnel design – Exit portal profil
� Impulse loss - Profile at portal
acc. to I.E. Idelchik - “Handbook of hydraulic resistance”
zzzz = 3.67Asymmetric
zzzz = 1.55 to 2.0Parabolic
zzzz = 1Uniform
Resistance CoefficientPictureProfile Typesat Exit Portal
Witt&Sohn AG Aug-11Banana Jet ®
Increasing efficiency by reducing avoidable losses
To reduce losses by different friction effects, guide vans are often used to direct the airstream towards the tunnel centre and away from the ceiling or walls.But guides vanes have at least negative impact on the generated sound level.
There for Witt & Sohn considered bending the silencers at an angle of 5-10°
The Banana Jet design was created!
Traditional Jet Banana JetBanana Jet ®®
Witt&Sohn AG Aug-11Banana Jet ®
Increasing thrust efficiency
� Technical� Increased thrust efficiency in the tunnel
Banana JetBanana Jet ®®
Traditional Jet
KempfCoanda
Backgroung velocity
by reductionof losses
Witt&Sohn AG Aug-11Banana Jet ®
Banana Jet advantages regarding the wall effect
� Reduction due to „No“ wall effect(depending on type of installation)
~2-5%~0%~0%Loss of thrust,Banana JetBanana Jet ®®
- (18-30%)- (15 - 25%)- (5 - 15%)Reduction of required thrust
20-35%15-25%5-15%Loss of thrust, Traditional Jet
K1
1−≈2
K1
1
−≈3
K1
1
−≈
Witt&Sohn AG Aug-11Banana Jet ®
Net outlet vel. cout, n
Background velocity - Effects on the jet impuls
� Impulse loss - Background velocity� Reduces gross outlet velocity
(to increase average tunnel speed)
Gross outlet vel. cout, g
Background vel. cBG
cBG
cout, g
cout, ncBG
=
-
Witt&Sohn AG Aug-11Banana Jet ®
� Different profiles:� Traditional Jet Fan
� Inhomogeneous air profile
� High velocity at wall/ ceiling
� Banana Jet ®® Fan� Homogeneous air profile
� Reduced velocity at wall/ ceiling (~80%)
0 20 40 60 80 100 air velocity [%]
road
Traditional Jet
tunnel ceiling
road0 20 40 60 80 100 air velocity [%]
Banana JetBanana Jet ®®
tunnel ceiling
Background velocity - Effects on the jet impuls
Witt&Sohn AG Aug-11Banana Jet ®
Effects - Geometry
� Losses by tunnel (case-to-case)� Geometry e.g. curves, slope� Obstacles close to the jet fan outlet
� niches, traffic signs, etc.
Traditional Jet
Witt&Sohn AG Aug-11Banana Jet ®
Effects - Geometry
� The Banana JetBanana Jet ®®:� NO losses by wall effect� Reduced losses by obstacles
Banana JetBanana Jet ®®
Witt&Sohn AG Aug-11Banana Jet ®
� Impulse loss - Profile at portal:� Short distance of last jet fan battery to exit portal (< 100m) due to cost
savings for cables
Effects- Portal
Traditional Jet
tunnel ceiling
portal
road
Banana JetBanana Jet ®®
tunnel ceiling
portal
road
zzzz = 1.02 to 1.05zzzz = 1.08 to 1.25
Witt&Sohn AG Aug-11Banana Jet ®
Why BJ gains higher efficiency - First summary
� 5 main effects(1) explain higher efficiency(2): � Flow/ friction losses due to
� Coanda effect
� No Impulse losses due to� Background velocity
� Wall effect (Kempf)
� Tunnel discharge profile at portal
� Influence of tunnel geometry
(1) no congestion, no piston,no chimney effect
(2) compared to Traditional Jet Fan
Witt&Sohn AG Aug-11Banana Jet ®
Increasing efficiency – Saving money
� Commercial aspect:� Higher efficiency of the TVS
(Tunnel Ventilation System):
� Smaller fans or lower number of fans can be used� Lower costs of investment, installation, operation, maintenance
el
BGTVS P
c~
Ση
Witt&Sohn AG Aug-11Banana Jet ®
Reducing electrical consumption
BananaBanana JetJet ®®
Traditional JetINPUT: Pel
OUTPUT: cBG, TJ = cBG, BJBJ
cBGINPUT: Pel
ηTVS, BJBJ > η η η η TVS, TJ
INPUT: Pel, TJ > Pel, BJBJ
INPUTOUTPUT=η
el
BGTVS P
c~η
Witt&Sohn AG Aug-11Banana Jet ®
Test in Tunnels - Results
� Comparative tests in 3 tunnels
Uznaberg West Tunnel
Switzerland
Collombey Tunnel Switzerland
Krohnstieg TunnelGermany
Witt&Sohn AG Aug-11Banana Jet ®
Test in Tunnels - Results
� Test set-up:� Banana JetBanana Jet ®® Fan :
� Modified to Traditional Jet Fan:
Witt&Sohn AG Aug-11Banana Jet ®
Test in Tunnels - Results
� Test set-up:
� same quantity
� same size
� same performance
same INPUT
Witt&Sohn AG Aug-11Banana Jet ®
Test in Tunnels - Results
� Test procedure:Grid-measurement of air velocity 1)
1) acc. to Log-Tchebycheff-Method
Witt&Sohn AG Aug-11Banana Jet ®
Test in Tunnels - Results
� Hypothesis:
„With same INPUT the Banana Jet ® fan
� has higher effective thrust, i.e.
� produce higher tunnel air velocity, i.e.
provides higher „OUTPUT“
Witt&Sohn AG Aug-11Banana Jet ®
Test in Tunnels - Results
� Results of air velocity profiles (3D)
Ref. chart: velocity [m/s]
0.0 15.012.03.0 6.0 9.0
BananaBanana JetJet ®® FanFan
Witt&Sohn AG Aug-11Banana Jet ®
Banana Jet ®
Trad. Jet
Test in Tunnels - Results
� Results of performance in tunnel
Effective thrust
T in % of Traditional Jet Fan
0 25 50 75 100 125 150
Tunnel air velocity
cBG in m/s
0 1 2 3 4 5 6 7 8
UznabergUznaberg
CollombeyCollombey
KrohnstiegKrohnstieg
Banana Jet ®
Trad. Jet
Banana Jet ®
Trad. Jet
Witt&Sohn AG Aug-11Banana Jet ®
Test in Tunnels - Results
� Reference: Bypass Schmerikon
Location Switzerland, Kanton St. GallenLength 1 x 1318 m + 2 x 940 mTraffic bidirectional + unidirectionalRealized 2003Tests Banana effect proven by
independent measurements
115100%Tunnel average velocity
%
kW
kW
N
N
-
132100Total thrust tunnel
548.1 (85%)640.5 (100%)Pelectric total
26.130.5Pelectric per fan
16170 (80%)20286 (100%)Thrust, total
770 (80%)966 (100%)Thrust per fan
2121Quantity of fans
Realized with Banana Jet ®Design schedule
Source: Witt & Sohn analysis
Witt&Sohn AG Aug-11Banana Jet ®
Test in Tunnels - Results
� Reference: Tunnel AubingLocation Motorway ring (Munich)Length 2 x 1950 mTraffic unidirectionalRealized 2005 - 2006Tests Banana effect proven by
independent measurements
144100%Total thrust tunnel
120100%Tunnel average velocity
kW
kW
N
N
-
1003 (80%)1254 (100%)P electric total
20.920.9P electric per fan
24768 (80%)30960 (100%)Thrust, total
516516Thrust per fan
48 (80%)60 (100%)Quantity of fans
Realized with Banana Jet ®Design schedule
Source: Witt & Sohn analysis
Witt&Sohn AG Aug-11Banana Jet ®
CFD-Simulation
� Results – vector diagrams
6.T/B : Round tunnel profile, 1 Fan @ centre, size 1250
9.T/B : Square tunnel profile, 1 Fan @ centre, size 1250
Witt&Sohn AG Aug-11Banana Jet ®
CFD-Simulation
� Results – air velocity, empty tunnel
1.T/B : Square tunnel profile, 1 Fan @ centre, size 710:
4.T/B : Square tunnel profile, 2 Fans @ corner, size 710:
9.T/B : Square tunnel profile, 1 Fan @ corner, size 1250:
TJ
BJ
TJ
BJ
TJ
BJ
Witt&Sohn AG Aug-11Banana Jet ®
CFD-Simulation
� Results – air velocity, traffic jam
� Losses by cars: -2 .. -12% � -6%(compared to empty tunnel)
1.T/B : Square tunnel profile, 1 Fan @ centre, size 710:
2.T/B : Square tunnel profile, 1 Fan @ corner, size 710:
TJ
BJ
TJ
BJ
Witt&Sohn AG Aug-11Banana Jet ®
33 %
23 %
30 %27 %24 %21 %18 %15 %
34 %31 %28 %25 %21 %19 %
42 %39 %37 %34 %32 %29 %27 %
48 %45 %42 %39 %37 %35 %33 %
50 %48 %45 %43 %40 %38 %35 %
56 %53 %50 %47 %44 %41 %38 %
55 %52 %50 %47 %45 %43 %41 %
60 %57 %55 %52 %50 %47 %45 %
CFD-Simulation
� Prediction for Banana Banana JetJet ®®-advantage
8 m/s7 m/s6 m/s5 m/s4 m/s3 m/s2 m/s
Thrust improvement [%] 1 towards TJat different tunnel air speeds [ m/s]
Configuration
1 tolerances: +/- 10%
Preliminary
� Actual measurements of tested tunnel
Bold � Results of CFD analysis
Rest � Predicted values
Witt&Sohn AG Aug-11Banana Jet ®
CFD-Simulation
Configuration
Losses by the 3 sides of the niche reduced
Losses by the 2 sides of the corner reduced
Niche acts as BJ � Coanda effect reducedBJ reduces interaction between both fans
Less interaction of both fans
Niche acts as BJ � Coanda effect reduced
Air is not travelling down the side walls
Mainly Coanda effect
Coanda effect + less interaction of both fans
Preliminary
Reasons for BananaBanana JetJet ®®-advantage
Witt&Sohn AG Aug-11Banana Jet ®
Commercial benefits
� Cost SAVINGS � Case A:
Smaller size / same quantity of fans
�Less CONSTRUCTION costs
�Less INVESTMENT costs
�Less RUNNING costs
�Smaller POWER SUPPLY PLANT
Witt&Sohn AG Aug-11Banana Jet ®
Commercial benefits
� Cost SAVINGS
� Case B:Less quantity/ same size of fans�Less CONSTRUCTION costs�Less INVESTMENT costs�Less RUNNING costs �Smaller POWER SUPPLY PLANT�Less INSTALLATION costs�Less MAINTENANCE costs
Witt&Sohn AG Aug-11Banana Jet ®
Benefits – General Contractor
� Cost SAVINGS:1. CONSTRUCTION:
�Smaller cross section/ excavation
�No performance losses by� Obstacles (e.g. traffic signs, lights)� Use of niches
! ! ! !
Standard Jet
HDVHDV CAR
BANANA Jetwith niches
CAR
Witt&Sohn AG Aug-11Banana Jet ®
(1) E90-cable costs: 25 – 58 €/m (incl. installation)(2) discount rate: 10%
Benefits – E&M Contractor
2. INVESTMENT:� Smaller size or reduced quantity
(FANS and CABLES)
Krohnstieg
Collombey
Uznaberg
Krohnstieg
Collombey
Uznaberg
~ 18 %~ 18 %~ 25 %~ 25 %
~ 29 %
~ 23 %
~14 %
~ 11 %
~ 10 %
BananaBanana JetJet ®®
~ 13 %~ 13 %
Fans (2)
~~ 41 %41 %Cables (1)
~~ 34 %34 %
~ 22 %~ 22 %
~ 15 %~ 15 %
Standard Jetin % of total costs
Savings for Fan & Cables
~ 30 %
Witt&Sohn AG Aug-11Banana Jet ®
~86+5 (1)2.0D: -12~93
~86+4 (1)1.5D: -10~92
with silencersincreased level(battery)
silencer‘sattenuation
w/o. silencers
~86+5 (1)1.5D: -10~91
Benefits – E&M Contractor
2. INVESTMENT: � Shorter/smaller SILENCER
� Same total SOUND level(*)
� Table:Sound pressure levels, 3m, 45°, ff [dB(A)]:
(*): with same total thrust (1): experienced values
Savings for shorter silencers
~ 15 to 40 %
Witt&Sohn AG Aug-11Banana Jet ®
Benefits – Client
3. RUNNING costs:� Less unit power consumption or
reduced quantity
(1) basis:operation time: 1000h p.a.energy cost: € 0,1 kW/h
~ 35 %~ 35 %
~ 33 %
~ 38 %
Banana JetBanana Jet ®®
~ 53 %Uznaberg
~ 53 %Krohnstieg
~ 44 %Collombey
Standard Jetin % of total costs
Savings for Running costs
~ 30 %
Witt&Sohn AG Aug-11Banana Jet ®
Benefits – all parties
� Total SAVINGS (investment + running)
running costs
cable costs
investment costs
Ban
ana
Ban
ana
Jet
Jet®®
Tra
ditio
nal J
et
Ban
ana
Jet
Ban
ana
Jet®®
Tra
ditio
nal J
et
Ban
ana
Jet®
Tra
ditio
nal J
et
Savings of 20 years
Total Project Costs
~ 30 %
Witt&Sohn AG Aug-11Banana Jet ®
4. Installation (mounting):� E.g. directly under ceiling
�No wall effect (Kempf)
�Less space consumption�Simple mounting structure�Less quantity of fans (Case B)
Benefits – E&M Contractor
ceiling
Banana JetBanana Jet ®®
ceiling
Traditional JetTraditional Jet
Witt&Sohn AG Aug-11Banana Jet ®
5. Environment:
� Pollution: 550g CO2 / kWh (1) (or higher)
� ~ 30 % CO2-reductio (in line with reduced power consumption)
� Fulfilment of latest UN-report, part 3 (climate crisis)
Benefits – Environment
(1) based on 60% fossil, 30% nuclear, 10% renewable(German Energy Mix/ Power Generation Standards)
Witt&Sohn AG Aug-11Banana Jet ®
References
6. References - worldwide:
1
9
13
4
2
3
1
4
Tunnels
Portugal
Norway
Germany
France
China
Chile
Austria
Australia
Country
1Venezuela
56
1
1
8
1
5
1
1
Total
UK
U.A.E.
Swizerland
Sweden
Spain
Singapore
Russia
TunnelsCountry
15.03.2011
Witt&Sohn AG Aug-11Banana Jet ®
Banana Jet advantages - Summary
� 20-60% higher effective thrust with Banana Jets (samefan size)
� Easy selection� Comfortable integration into tunnel concept� Great benefits (cost savings) for all parties� Helps to reduce CO2
� Proven in over 50 tunnels WORLDWIDE
Banana JetBanana Jet ®®
PPatentatent No. No. 10506841050684