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University of Patras Department of Electrical and Computer Engineering Electric Power Systems High Voltage Laboratory

5th and  6th  MARINELIVE  Workshop    

Simulation of Lightning Effects on Metallic Ships G. D.  Peppas  1,  A.  G.  Telonis  1,  E.  P.  Nicolopoulou2,  ,  I.  F.  Gonos2,  E.  C.  Pyrgio=1,    I.  A.  Stathopulos2    1  Electrical  and  Computer  Engineering,  U.  Patras,  Greece   2  School  of  Electrical  and  Computer  Engineering  ,Nat.  Tech.  U.  Athens,  Greece  

hEp://www.hvl.ece.upatras.gr/


Introduc;on Data  collec;on    

• Regula=ons and  standards  are  collected  regarding   lightning  striking  ships,  and  the  safety  risks  for  humans  and   vessels    

•  Historic  data  on  lightning  

The High  Voltage  Laboratory  of   University  of  Patras  has  been  collec=ng   such  data  for  a  long  period.   hEp://www.hvl.ece.upatras.gr/  


Lightning Strike  Current   Ιmax k τ1 τ2

peak current correction factor front time constant tail time constant

Lightning current  waveshape   10

⎛ t ⎞ ⎜⎜ ⎟⎟ t − I max ⎝ τ 1 ⎠ τ2 I (t ) = ⋅ ⋅ e 10 k ⎛ t ⎞ 1 + ⎜⎜ ⎟⎟ ⎝ τ 2 ⎠

Simula=on model  of  a  lightning     hEp://www.hvl.ece.upatras.gr/  


Does lightning  hit  the  sea?  

Annual strikes  per  km2   h6p://geology.com/ar:cles/lightning-­‐map/  

Global lightning  maps,  strikes/km2/year   h6p://science.nasa.gov/science-­‐news/science-­‐at-­‐nasa/2001/  

hEp://www.hvl.ece.upatras.gr/


Does lightning  hit  the  sea?   Snapshot  of  live  lightning  detec=on   maps  in  Southwest  Europe  

• Lightning strikes  hit  the  sea   • Ships  are  possible  lightning   strike  targets  

www.Blitzortung.org/Webpages/index.php

hEp://www.hvl.ece.upatras.gr/


Goals of  current  Simula=on   •  Using  Opera  3d  →  Simula:on  of  lightning  effects  on   metallic  ships   •  2  ships  with  different  dimension   •  4  points  of  lightning  strike  in  each  ship   •  Results  of  the  current  density  J  (A/m2)  

hEp://www.hvl.ece.upatras.gr/


Opera 3d  Cobham   Ø OPera=ng  environment  for  Electromagne=c   Research  and  Analysis   –  Pre-­‐Processor   –  Modeller   –  Post-­‐Processor  

hEp://www.hvl.ece.upatras.gr/


Opera 3d  Cobham   Ø FEM  (Finite  Element  Method)    -­‐  is  used  to  obtain  solu=ons  to  integral  equa=ons  that  can  not  be  solved  by  

analy=c method    -­‐  division  of  the  structure  into  small  volumes    -­‐  applicable  to  any  type  of  non-­‐linearity    

Ø   The  Tosca  Algorithm   •   Sta=onary  electrosta=c      

hEp://www.hvl.ece.upatras.gr/


Opera 3d  Cobham   Ø The  Tosca  Algorithm   Faraday  

Poisson

Sta=onary electrosta=c    fields    

Sta=onary magne=c   fields  

Laplace

Magnetic Fields Tangential Magnetic Normal Magnetic

Boundary Conditions Field Symmetry H·n=0 H×n=0

Scalar Potential ∂φ/∂n=0 φ= constant

Electric Fields or Current Flow

Field Symmetry

Scalar Potential

Tangential Electric

E·n=0

∂V/∂n=0

Normal Electric

H×n=0

V=constant

H: magnetic field intensity(Α/m) Ε: electrical field intensity(V/m)

hEp://www.hvl.ece.upatras.gr/


Ship Models   USS  Somerset  

HMS Albion  

Ships

USS Somerset

HMS Albion

Difference

Length (m)

118

175

57

Beam (m)

12.5

29

16.5

Height (m)

15

28

13

hEp://www.hvl.ece.upatras.gr/


Ship material  proper=es  

 

Hull

Carbon steel  (Stainless  Steel,   Aluminium)   Rela=ve  permi]vity  →  107   Conduc=vity  →  6,99·∙106  S/m  

Salt Water  

Rela=ve permi]vity  →  85   Conduc=vity  →  4,8  S/m    

Discon:nuity, imperfect  joints  and  material   changes  were  not  included  in  the  analysis     hEp://www.hvl.ece.upatras.gr/  


Generate Surface  Mesh  

• Different mesh  in  surfaces   with  different  interest     accuracy↑   • Mesh↑                errors↓      =me  ↑     • Mesh  ↓    =me  ↓  

hEp://www.hvl.ece.upatras.gr/


Lightning Approach   Peak  Current  

Impact Surface  (0,2m)x(0,2m)  

hEp://www.hvl.ece.upatras.gr/


Lightning Approach  

•  Points  decision  based  on  maximum   lightning  strike  probability     •   4  points  in  each  ship    (stern,  top1,  top2,  bow)   Choose  Surface  →  Set  Boundary  Condi=ons  →    →  Current  Source  →  100.000A  

hEp://www.hvl.ece.upatras.gr/


Post-­‐Processor Ø Current  density  J  (A/m2)    

• Surface colored  contours   • Vectors  

hEp://www.hvl.ece.upatras.gr/


USS Somerset  Stern   Ships Length (m)

USS Somerset 118

HMS Albion 175

Beam (m)

12.5

29

Height (m)

15

28

First Point  of  lightning  strike  →  Stern  

Peak Current  Density  →  J=2.5·∙106A/m2   (Jds=I→J·∙0.2m·∙0.2m=100kA)    ↓                                          same  result  in  all  cases  studied  

hEp://www.hvl.ece.upatras.gr/


Point of  lightning  strike  →  Ship1  Stern  

Current Density    500A/m2  ≤  J  ≤  2500A/m2     Vectors  show  direc=on  of  J   Size  of  vectors  show  volume  of  J   hEp://www.hvl.ece.upatras.gr/  


USS Somerset  Top  1   • Point  of  lightning  strike  →  first  top   • Height  =  13m   • Vectors  show  the  point  of  the   lightning  strike  and  the  direc:on  of   current  density  

hEp://www.hvl.ece.upatras.gr/


Point of  lightning  strike  →Ship1  Top  1  

Ship with  mesh  

 

Current Density  +  Vectors  

Current  Density  values:    200A/m2  ≤  J  ≤  5000A/m2    

hEp://www.hvl.ece.upatras.gr/  


Point of  lightning  strike  →  Ship1  Top  1   LN(J)  

8103 A/m2  

2980 A/m2  

1096 A/m2  

403 A/m2  

148  A/m2  

54  A/m2  

LN(J)=10 →  J=e10=22026.5  A/m2     LN(J)=4      →  J=e4=54.598  A/m2       LN(J)  gives  detailed  perspec;ve  

Ship  with  mesh  

hEp://www.hvl.ece.upatras.gr/


USS Somerset  Top  2  

Peak Current  Density   J=2.5·∙106A/m2    

• Point of  lightning  strike  →  second  top   • Height  =  15m   • Highest  point  of  USS  Somerset   • Vectors  show  the  point  of  the  lightning   strike  and  the  direc:on  of  current  density  

hEp://www.hvl.ece.upatras.gr/


Point of  lightning  strike  →Ship1  Top  2  

Current Density   500A/m2  ≤  J  ≤  1500A/m2  

Ø  Similar  results  to  Top  1  

Ship  with  mesh  

hEp://www.hvl.ece.upatras.gr/


Point of  lightning  strike  →Ship1  Top  2  

8103 A/m2  

2980 A/m2  

1096 A/m2  

403 A/m2  

LN(J)=10 →  J=e10=22026.5  A/m2       LN(J)=5      →  J=e5=148.413  A/m2      

LN(J) gives  more  detailed  perspec;ve     than  specific  range  of  values  

hEp://www.hvl.ece.upatras.gr/


USS Somerset  Bow  

•  Point  of  lightning  strike  →  Bow  (front)   •   Vectors  show  -­‐the  point  of  the  lightning  strike                        -­‐the  direc;on  of  Current  Density                        -­‐the  volume  of  Current  Density   hEp://www.hvl.ece.upatras.gr/  


Point of  lightning  strike  →Ship1  Bow  

 

  Current  Density  values   200A/m2  ≤  J  ≤  3000A/m2  

Ship  with  mesh  

hEp://www.hvl.ece.upatras.gr/


Point of  lightning  strike  →  Ship  1  Bow  

8103 A/m2  

2980 A/m2  

1096 A/m2  

403 A/m2  

148 A/m2  

Current Density  Values   LN(J)=10  →  J=e10=22026.5  A/m2       LN(J)=4      →  J=e4=54.598  A/m2    

hEp://www.hvl.ece.upatras.gr/


HMS Albion   Ships Length (m)

USS Somerset 118

HMS Albion 175

Beam (m)

12.5

29

Height (m)

15

28

•  4  points  chosen  for  lightning  strikes   •   100  kA  Boundary  Condi=on   •   Surface  of  strike  (0.2m)x(0.2m)  

hEp://www.hvl.ece.upatras.gr/


HMS Albion  Stern   First  Point  of  lightning  strike  →  S    tern      

Current Density  values   50A/m2  ≤  J  ≤  1500A/m2  

Ship  with  mesh  

hEp://www.hvl.ece.upatras.gr/


Point of  lightning  strike  →Ship  2  Stern  

Current Density  Values   LN(J)=7      →  J=e7=1096.63  A/m2       LN(J)=4      →  J=e4=54.598  A/m2     hEp://www.hvl.ece.upatras.gr/  


HMS Albion  Top  1   •     Lightning  strike  at  second   highest  point   • Height=27m   •   Possible  antennas  in  Top  1  

hEp://www.hvl.ece.upatras.gr/


Point of  lightning  strike  →Ship  2  Top  1  

Current Density  Values   10000A/m2  ≤  J  ≤  70000A/m2  

Peak Current  Density  →  J=2.5·∙106A/m2   hEp://www.hvl.ece.upatras.gr/  


Point of  lightning  strike  →Ship  2  Top  1  

Current Density  Values  +  Vectors   100A/m2  ≤  J  ≤  5000A/m2  

Ship  with  mesh  

hEp://www.hvl.ece.upatras.gr/


Point of  lightning  strike  →Ship  2  Top  1  

Ship  with  mesh  

Current Density  Values   LN(J)=10  →  J=e10=22026.5  A/m2       LN(J)=4      →  J=e4=54.598  A/m2     hEp://www.hvl.ece.upatras.gr/  


HMS Albion  Top  2   Current  Density  Values   100A/m2  ≤  J  ≤  8000A/m2   •   Possible  antennas  at  Top   2   •   Highest  point  of  the  ship   •   Height=29m  

Difficult to  show  volumes  of  current   density  for  the  whole  ship  

hEp://www.hvl.ece.upatras.gr/


Point of  lightning  strike  →  Ship  2  Top  2  

8103 A/m2  

2980 A/m2  

403 A/m2  

148  A/m2  

54  A/m2  

Current Density  Values   LN(J)=10  →  J=e10=22026.5  A/m2       LN(J)=3      →  J=e3=20.086  A/m2    

•  LN(J)  gives  detailed   perspec;ve  for  the  whole  ship   hEp://www.hvl.ece.upatras.gr/  


HMS Albion  Bow  

•   Final  point  of  possible  lightning   strike→  Bow  (front)   •   Different  geometry  of  vectors    in   comparison  with  stern  

hEp://www.hvl.ece.upatras.gr/


Point of  lightning  strike  →  Ship  2  Bow   Current  Density   100A/m2  ≤  J  ≤  1500A/m2  

USS Somerset   HMS  Albion   Strike  point   J  at  stern  

Bow

Bow

<200A/m2

<600A/m2

hEp://www.hvl.ece.upatras.gr/


Point of  lightning  strike  →  Ship  2  Bow   Current  Density  Values   LN(J)=10  →  J=e10=22026.5  A/m2       LN(J)=3      →  J=e3=20.086  A/m2     8103  A/m2  

2980 A/m2  

1096 A/m2  

403 A/m2  

148  A/m2  

54  A/m2  

hEp://www.hvl.ece.upatras.gr/


Conclusion •  Results  of  Simula=on    -­‐Different    current  density  volumes    resulted  in  ships  with  different  dimensions  and  

geometric shapes    -­‐Similar  route  was  observed  for  current  density  (J)  of  both  ships    -­‐Metallic  ships  give  lightning  a  faster  conduc=ve  way  to  sea  water  

•  Lightning

Antennas, electronic  devices  and  external   equipment  are  exposed  to  direct  lightnings   Possible  threat  when  people  are  working   exposed  on  the  deck    

•  Protec;on  against  direct  lightning  for  external  equipment  with  lightning  rods   and  with  use  of  SPD’s  

There is  need  for  a  comprehensive  research  and  set  of  guidelines  to  protect  the   equipment  and  structures  of  naval  ship,  ,  against  direct  and  indirect  effects  of   lightning.   hEp://www.hvl.ece.upatras.gr/  


Further Inves=ga=on   Ø     It  is  substan=al  to  study  the  modeled  ship,  stressed  with  a  full  wave  

lightning strike  in  order  to  simulate  the  electromagne=c  fields    in  =me   domain.   Ø   Addi=onal  research  is  running  concerning  joints,  glass  surfaces  and   discon=nui=es  for  more  detailed  and  accurate  model  analysis.  

hEp://www.hvl.ece.upatras.gr/


5th and  6th  MARINELIVE  Workshop  

This research  has  been  co-­‐financed  by  the  European  Union  (European  Social  Fund  –  ESF)   and   Greek   na=onal   funds   through   the   Opera=onal   Program   "Educa=on   and   Lifelong   Learning"   of   the   Na=onal   Strategic   Reference   Framework   (NSRF)   -­‐   Research   Funding   Program:   THALES:   Reinforcement   of   the   interdisciplinary   and/or   inter-­‐ins=tu=onal   research  and  innova=on  

hEp://www.hvl.ece.upatras.gr

Simulation of lightning effects on metallic ships  
Simulation of lightning effects on metallic ships  
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