1.0 Introduction
This document identifies some of the writer’s experiences with the TB and is based on operating experience, field tests and assessments. The information has not necessarily been formally approved by calculations or development activity.
It is not an exhaustive list because many of the answers provided to
questioners are not necessarily based on hard evidence. It is often a case of linking various remembered facts that may not documented anywhere but which enable a solution to be provided.
This document is part of three lever arch files of TB useful information which has been filed within the library system
Compiled By:
R W Kemp
Principal Engineer
2.0 Design Concept
The mathematical tools and material properties available during the design of the TB turbine were not as well advanced as they are today and therefore a conservative approach was made to stress and safety margins. Because of this many of the components within the turbine are quite tolerant of any deviations from the design intent.
The original design of the TB was made in the late 1960’s and it was conceived as a 3000 hp twin shaft turbine for both mechanical and electrical drive duties. In reality the first turbines built did not have an interduct and there were so many internal leak paths that only 2000 hp was produced.
An interduct was introduced between the ct and pt and the pt1 stator was reduced. This improved the flow characteristics and after most of the leak paths were eliminated the 3000 hp was achieved. Since that time the power has been increased three times to 4000 hp, 5000 hp and finally 5400 hp.
After the initial development modifications, there has been very little change in the mechanical arrangement since its conception.
The gas generator consists of a simple 13 stage compressor with C4 profiles and a two stage compressor turbine with shrouded rotor blades. The simple reverse flow combustion chambers are external to the pressure casing giving a shortened overall length for the engine and easy maintenance of the combustors. Following a departure with the SGT100 and 200 turbines this concept was resurrected for the 300 and 400 machines.
As a twin shaft machine the gas generator speed varies with load. It operates between about 7200 rpm when idling to about 10400 rpm at full load under ISO conditions.
Under some conditions the speed can be as high as 10900 rpm but this should be considered the maximum permissible.
The unshrouded two stage free power turbine is supported from the gear box casing which is effectively the fixed support for the turbine. All axial expansion is accommodated by the A frame supporting the compressor inlet.
The design speed for the power turbine is 7950 rpm but it can operate as low as 4000 rpm and up to a maximum permissible continuous speed of 9000 rpm. This top speed is inclusive of any matching allowance but the overspeed trip can be set to 9900 rpm; 10% above the max continuous.
This document identifies some of the writer’s experiences with the TB and is based on operating experience, field tests and assessments. The information has not necessarily been formally approved by calculations or development activity.
It is not an exhaustive list because many of the answers provided to
questioners are not necessarily based on hard evidence. It is often a case of linking various remembered facts that may not documented anywhere but which enable a solution to be provided.
This document is part of three lever arch files of TB useful information which has been filed within the library system
Compiled By:
R W Kemp
Principal Engineer
2.0 Design Concept
The mathematical tools and material properties available during the design of the TB turbine were not as well advanced as they are today and therefore a conservative approach was made to stress and safety margins. Because of this many of the components within the turbine are quite tolerant of any deviations from the design intent.
The original design of the TB was made in the late 1960’s and it was conceived as a 3000 hp twin shaft turbine for both mechanical and electrical drive duties. In reality the first turbines built did not have an interduct and there were so many internal leak paths that only 2000 hp was produced.
An interduct was introduced between the ct and pt and the pt1 stator was reduced. This improved the flow characteristics and after most of the leak paths were eliminated the 3000 hp was achieved. Since that time the power has been increased three times to 4000 hp, 5000 hp and finally 5400 hp.
After the initial development modifications, there has been very little change in the mechanical arrangement since its conception.
The gas generator consists of a simple 13 stage compressor with C4 profiles and a two stage compressor turbine with shrouded rotor blades. The simple reverse flow combustion chambers are external to the pressure casing giving a shortened overall length for the engine and easy maintenance of the combustors. Following a departure with the SGT100 and 200 turbines this concept was resurrected for the 300 and 400 machines.
As a twin shaft machine the gas generator speed varies with load. It operates between about 7200 rpm when idling to about 10400 rpm at full load under ISO conditions.
Under some conditions the speed can be as high as 10900 rpm but this should be considered the maximum permissible.
The unshrouded two stage free power turbine is supported from the gear box casing which is effectively the fixed support for the turbine. All axial expansion is accommodated by the A frame supporting the compressor inlet.
The design speed for the power turbine is 7950 rpm but it can operate as low as 4000 rpm and up to a maximum permissible continuous speed of 9000 rpm. This top speed is inclusive of any matching allowance but the overspeed trip can be set to 9900 rpm; 10% above the max continuous.
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