31st Oct 2012, 22:58
permalink Post: 1692
593 smoke reduction
ref question from Joliste
As I was working my way from 1 to 85 I read the above which reminded of a paper I filed 35 years ago:
"Development of Pollution Controls for Rolls-Royce RB211 and Olympus 593 Engines" by A B Wassall. I have picked out stuff relevant to the question:
The engines of the day generated smoke in the primary zone and partially consumed it in the rest of the combustor.
It was easier to reduce the production than increase the consumption but leaning the primary zone had an adverse effect on relight capability which then needed its own corrective action as was done on the 211. Metal temperatures went up with the leaning (as intimated by Joliste)
The 593 did not have the leaning option as it had to maintain an over-rich primary zone at TO to ensure an adequate weak extinction margin when throttled back at completion of supersonic cruise when the combustor had to operate at A/F ratios over 180.
In addition to the smoke problem the combustor weight and pressure loss had to be reduced.
These other two requirements led to the annular combustor and vaporizers which also reduced the smoke substantially. These three benefits were expected based on Pegasus experience.
Quote:
|
why were the Olympus 593 s so smoky to start with, did they use excess fuel to help with cooling as some petrol engines do or was there some design feature which caused the smoke. It seeems to have been cured in later engines
rod |
"Development of Pollution Controls for Rolls-Royce RB211 and Olympus 593 Engines" by A B Wassall. I have picked out stuff relevant to the question:
The engines of the day generated smoke in the primary zone and partially consumed it in the rest of the combustor.
It was easier to reduce the production than increase the consumption but leaning the primary zone had an adverse effect on relight capability which then needed its own corrective action as was done on the 211. Metal temperatures went up with the leaning (as intimated by Joliste)
The 593 did not have the leaning option as it had to maintain an over-rich primary zone at TO to ensure an adequate weak extinction margin when throttled back at completion of supersonic cruise when the combustor had to operate at A/F ratios over 180.
In addition to the smoke problem the combustor weight and pressure loss had to be reduced.
These other two requirements led to the annular combustor and vaporizers which also reduced the smoke substantially. These three benefits were expected based on Pegasus experience.
23rd Feb 2013, 09:06
permalink Post: 1701
Quote:
| As a Chartered Engineer working on a multi-disciplinary rail project, I am amazed that a project as complex as this was managed across the Channel in the 1960's; how was the Systems Engineering managed - who drove the requirements for the Jet, potential carriers, engineers or politicians? |
Once it was decided to go, I would say that the system requirements were largely driven by the difficulty of the task - more a question of finding out how to make it work than of optimising. The overall aircraft requirements were driven by the engineers, but criticised by the potential customer airlines in regular meetings.
Safety requirements were specified in a completely new airworthiness code - a sort of comprehensive set of special conditions, which were generally more severe than the subsonic codes of the time. Concorde, for example, was, AFAIK , the first civil aircraft to be certificated against the requirements that now exist as 25.1309.
But nobody really knew what to write for supersonic flight and, in particular, the transition from subsonic, so to some extent one made it up as one went along, using prudent common sense and engineering judgement. Fuel system transfer rates for example had to match a requirement that it should be possible to abandon the acceleration at any point and return safely to subsonic conditions - and the deceleration was much quicker than the acceleration!
Quote:
| wind modelling played a big part in the development of the aerodynamics, how big did the models go? Did you have the luxury of testing a full-scale model? or maybe full-scale parts or sub assemblies? |
Supersonic testing mainly at 1/30 scale; low speed 1/18. The biggest model was a 1/6 scale half model used mainly for icing tests. Isolated intake tests, IIRC, about 1/10 scale, but we did have a full scale intake operating in front of an Olympus 593 at Mach 2.0 in Cell 4 at NGTE Pyestock.
23rd Oct 2013, 13:49
permalink Post: 1751
Quote:
| I know Concorde engines were FADEC. Were the Thrust levers gated like on Airbus? I noticesd cocncorde pilots shovved the levers forward for take off thrust..not the gentle easing forward like most other turbojets..why was there this need?Did they take too much time to spool up? |
I suspect the zero bypass Ol 593 would take less time to spool up than todays high bypass engines.
23rd Oct 2013, 14:20
permalink Post: 1752
CliveL;
Re, "I suspect the zero bypass Ol 593 would take less time to spool up than todays high bypass engines. "
Yes, I think so. The A333 (RB211s) had a specific technique at high-altitude airports to ensure the engines were stabilized at about 1.1EPR before taking the thrust levers into the FLEX/MCT or TOGA detent. The thrust levers were taken to their detents 'gently', even as FADEC did control the acceleration. Even then, some surging was experienced, again at high-altitude airports, (CYYC for example).
Re, "I suspect the zero bypass Ol 593 would take less time to spool up than todays high bypass engines. "
Yes, I think so. The A333 (RB211s) had a specific technique at high-altitude airports to ensure the engines were stabilized at about 1.1EPR before taking the thrust levers into the FLEX/MCT or TOGA detent. The thrust levers were taken to their detents 'gently', even as FADEC did control the acceleration. Even then, some surging was experienced, again at high-altitude airports, (CYYC for example).