SC 2004
GEWiTTS – GRID Enabled Wind Tunnel Test Service
SC 2004
Outline
• The GEWiTTS project
• Manchester University Transonic Wind Tunnel and PSP system
• GEWiTTS software architecture
• Firewalls
SC 2004
GEWiTTS
• Vision: Authenticated collaborative synergy between computational and experimental facilities
• GRID Enabled Wind Tunnel Test Service– Aim: Remote operation of wind tunnel data acquisition systems in a collaborative, virtual
organisational environment– PSP system used as a vehicle that supports high data rates, adaptability and remote processing of
results
• Addressing issues of:-– Remote collaborative control of experiments– Safety critical systems– Data confidentiality (https:)– Authentication– Firewalls
• Project partners– BAE Systems Advanced Technology Centre– BAE SYSTEMS (Warton) Air Systems– Manchester Uni – ARA
SC 2004
Manchester University TWT
-Suck-down tunnel-M = 0.3-0.8-1 minute runtime-15 minutes duty cycle-Hazardous environment
SC 2004
Beam Steering Mirrors
LASER
Polymer and dye
Substrate
•Organic dye dissolved in gas permeable polymer absorbs green photons
•Re-radiates at longer wavelength
•Oxygen molecules in the polymer can quench this process
•Relationship between emitted photons and air pressure
•Real time data msec & sec timescales•Configurable on-the-fly
•Equivalent to computational steering•High data rates•Class IV laser
SC 2004
Chemistry Stuff
Metalloporphyrins
Visible wavelength absorption bands - 532nm coincides with freq doubled Nd:Yag
Useful (easily measurable) phosphorescence- 650nm
Platinum meso-Tetra-(pentafluorophenyl) porphine, Pt(TfPP).
Siloxane polymer - rubbery coating, 20-30m thick, high gas permeability
Permeability = ƒ(T)
SC 2004
Decay Lifetime Measurement System
Return signal is close to an exponential
independent of initial excitationno paint thickness/uniformity effectsno sensitivity to surface curvaturedye concentration or uniformity has little effectambient light levels are irrelevant
Reference image/measurement not required
Application to high data rates
Sufficient data for simultaneous two variable extraction (P+T)
SC 2004
ARA Wind Tunnel Tests
• Large Transonic Wind
tunnel In UK
• Fully automatic operation
• Data on-line within 5-ish
seconds
• Edge detection routines
used for model location
SC 2004
Approximate area covered byzoomed scan below
Bracket
Upper Surface Tailplane at M=0.8, 10o
SC 2004
Client 1
Client n
Wind tunnel 1
Wind tunnel n
GEWiTTS scenario
SC 2004
GEWiTTS software
• Servers– PSP system server
• Can support multiple clients– Tunnel Control System server– Interlocks
• Client– Can support multiple servers– Performs processing and display of results
• Management application– Health & Safety– Security– Validation– Collaborative working process
Portal – real time
SC 2004
List of experimental sessions being run at
the facility
List of clients taking part in each session and the controller of
the experiment
List of PSP servers in each session
Interface with tunnel control system
Video output to clients
SC 2004
List of active sessions
Status of client
Client interface
SC 2004
Lessons learned(1)
• Collaborative working
– Overall control of experiment rests with facility operator (H&S concerns)
– Partial control can be delegated– SessionManager (or portal) is tightly bound to facility
– Very similar to the dynamics of a meeting– Designation of experiment leaders and viewers is critical– Access is granted and validated on a session-by-session basis
– A separate dialogue application (a chatter example) is vital
– Good visual feedback on application status is essential in real time applications
SC 2004
Lessons learned(2)
• User or client validation
– Essential– User ID must propagate through audit trail
• Certificates allow single sign-on use-anywhere• Are usually not time-bound
– Solution is to generate unique ID at use time• Fingerprint ID allows access to .exe created for that user only• Timestamps
Fingerprint ID
Browser
Compile client.exe
Database
HTTPS
SC 2004
Firewalls and other irritations
• BAE Systems and its partners operate strict firewall policies
– Traversing multiple firewalls is a difficult but unavoidable task– Connections can only be initiated on http or https– Security and user validation is essential
• Export licenses
– Remote execution of code and data traversing international boundaries create specific problems
• ISO9001/2
– Audit trails – confidence that repeat computations give identical results
SC 2004
Summary
• PSP system and a wind tunnel can be operated remotely in a real-time multi-user collaborative working scenario for integration within the CFD driven design process
• Dynamics of a collaborative working environment mimic those of a traditional meeting, and software has been developed to reflect this