DRed and Design Folders
Rob Bracewell
Saeema Ahmed
Rob Bracewell
Contents
• What is DRed?
• Availability and support in collaborating
companies
• What do the companies see as benefits
of using DRed?
• Recent applications in design and in
problem diagnosis
• What is DRed like to use?
What is DRed?
• Design Rationale editor
– a software tool to replace the designer’s notebook
– a derivative of the venerable IBIS concept
– rationale captured in series of planar graphs
– nodes of graph linked to associated files stored in an
on-line Design Project Folder
• “Live” use by aerospace designers from v0.1
– just three weeks software development in first release
• Gradual tool development and steadily
Rob Bracewell
antle igb - scavenge
in E:/sync/DRedfiles/dave_w/rhb
last mod 11:59 Tue 13 Jul 2004
Security classification: Unclassified
What measures can be used to improve scavenge / avoid oil leaks?Remove floor of IGB sump to allow SAGB to be new IGB sump
Separate LP/IP and HP oil chambers and scavenge
Design simplification / weight & cost reduction
Risk of high HTO as IGB oil must pass through vane 6.
Extra scavenge route required
Partial separation of chambers already achieved via IP / HP baffle previously designed/manufactured for Trent 500 development test
Spare scavenge pump capacity available
Previous piped scavenge arrangement may be useful starting point for designing new scavenge route
More windage if RDS is not shrouded May be possible to use
existing lower scav. plate as new sump floor
Use of fabricated vane inner shroud to provide thermal insulating air gap
Space may be limited to fit vane shroud in between vane wall and RDS Could be made using
existing casting (re-worked)
Could be made to connect with existing scav / shroud fittings on lower sump plate
Suggested by oil systems May be difficult to create
reliable seal between the two chambers.
IS THIS NEEDED? New cast iron-type seal arngtrequired as splines at greater diameter than quill shaft
Increasing the shaft diameter may help the whirl margin -(currently 27%, should be 30%). Risk of increased windage if RDS is left unshrouded 1: to
antle igb - scav - lower sump floor: I:1
2: to
antle igb design issues: A:2
Availability and support in
collaborating companies
• New users attend a 2.5 hour, “hands on”,
introductory training course
– around 200 designers have now attended
– course now given by in-house training personnel
• DRed currently installed on 130 LAN PCs
– imminent plans to double this
Rob Bracewell
What do the companies see
as benefits of using DRed?
• Helps to structure, review and present design
thought processes
• Improved rigour in design and design review
• Capture DR for future use
– avoid reinventing the wheel
– avoid repeating mistakes
– faster, deeper understanding of past designs
• Time saved writing design reports
Recent applications in design
and in problem diagnosis
• Antle Transmissions Design
• Adour flame breakout,
• Submarines Main Coolant Pump rundown problem,
• JSF 3BSN
• 7e7 Combustor prelim design
• 7e7 Fan annulus filler design
• T500 HP Turbine fir tree failure understanding
Rob Bracewell
What do designers think of it?
• Questionnaire by Saeema Ahmed of users in Rolls-Royce:
• Found to be easy to use
– 14 out of 19 responses found easy or very easy
• Some immediate improvements to design process:
– 10 out of 10 found improved or slightly improved overall view of
design process
– 7 out of 10 found improved or slightly improved keeping track of
design process
– 6 out of 10 found improved or slightly improved evaluating and
deciding between concepts
– No (!) negative feedback, 0 out of 10 said hindered/slightly hindered
design process
• Designers perceive future benefits. Main benefits:
What is DRed like to use?
• Mobile Arm Support design example
– used previously in 2003 DTM paper
Conclusions and Future Work
• Gradual expansion of use in companies,
driven by user recommendation,
suggests
:
– designers find DRed useful, and easy to use
– maps naturally to designers’ thought processes
• There is still need for empirical evaluation!!!
• Research required on retrieval mechanisms
• Link to parametric CAD and numerical
Rob Bracewell
Conclusions and Future Work
• Gradual expansion of use in companies,
driven by user recommendation,
suggests
:
– designers find DRed useful, and easy to use
– maps naturally to designers’ thought processes
• There is still need for empirical evaluation!!!
• Research required on retrieval mechanisms
• Link to parametric CAD and numerical
