RUSTON GAS TURBINE TB5000 TB5400 DETAILED COMPONENT PERFORMANCE

DETAILED COMPONENT PERFORMANCE

Compressor and Diffuser

The performance of the engine compressor,

following the clearance adjustments, was found

to be very close to the rig measured results.

The basic parameters of engine measured mass

flow, efficiency and pressure ratio are

superimposed on the rig measured results in

Figure 5.

The reason for the starting ease is

apparent from Figure 5 where the surge line is

noted to be almost straight, therefore

offering a constant surge margin with speed.

 Compressor blade vibration characteristics

have been measured over a wide operating speed

range. Figure 6 shows the predicted Campbell

diagram for the first stage rotor blade with

the ratio of maximum measured dynamic strains

relative to the allowable super-imposed.

The compressor exit diffuser is also

observed to be performing close to design with

a recovery of .68 being achieved relative to

the expected level of .65. Figure 7 shows the

predicted pressure recovery along the diffuser

using STAR CD prediction code.

Turbine Cooling
Cooling validation on the turbine is
carried out on both engine and rigs, the
methods are well described in Reference 3 Figure 8 shows the installation of 0.25 mm
diameter thermocouples on the HP stator
blades. These thermocouples are used to
measure blade temperature and in conjunction
with gas temperature measurements via fixed
rakes the cooling effectiveness of the blading
is established. Figure 9 shows the measure-
ment of cooling effectiveness of the blade
relative to design predictions. The
results confirm the blade to be well cooled
with the leading and trailing edges being

close to prediction while the bulk of the

blade is slightly overcooled.

Similarly, measurements for the HP rotor

blade using infra-red optical pyrometry

measurement techniques confirmed that metal

temperatures were below 800°C as required to

achieve the required 40,000 hours creep rupture

life.

Turbine Blade Vibration

The two turbine rotor blades have been

subjected to an extensive design-validation

route to ensure their integrity. A full 3D

Finite Element model of the blades, including

cooling geometry, has been generated allowing

stress and vibration characteristics to be

established. Figure 10 compares the finite

element predicted vibration displacement modes

with the laser holographic measurements. To

establish the actual dynamic stress level,

however, engine strain gauge measurements are

essential where the effects of forcing,

damping and temperature are realised.

As with the compressor, radio telemetry, as

shown in Figure 11, is used to transmit the

signals from the rotor. Having overhung

turbine wheels allows simple access for wiring

from both discs and blades. Cooling of the

telemeter is essential, however, and

temperatures in the telemeter housing are

maintained below 100°C to protect the

electronic transmitters and batteries.

Figure 12 shows a typical spectrum

analysis of the HP rotor blade. The clarity

of the signal is evident from the trace. To

ensure all conditions are fully simulated the

engine was run at various loads and speeds and

transient operations including load shedding

and accepting. From the results the Campbell

diagrams can be produced as shown in Figure

13. To establish the maximum strains the FE

vibration model is used to relate the strain

gauge measurements to other areas of the blade

The interesting aspects of the HP rotor

blade are that the first natural frequency is

relatively high at 2625 Hz, therefore,

avoiding any low engine orders. Stator blade

interferences 40x and 52x, HP and LP res-

pectively, occur below running speed on the

4th and 6th modes. The stress levels, even

for these modes, are relatively low and do not

cause concern.

Rotor Dynamics

The dynamic performance of the gas turbine

rotor has been shown to be extremely robust

and stable with levels of vibrations well

within the required API levels. The rotor

bearing system has also been shown to be

relatively insensitive to bearing clearances.

Tests using a wide range of clearances on both

bearings gave an unchanged result in terms of

synchronous and subsynchronous levels. The

rotor operates between the second rigid body

mode and the first bending lateral. Figure 14

shows the unfiltered vibration amplitudes

results over the full speed range.

Combustion and Emissions

The development engines have been tested

on both natural gas and fuel oil over their

entire load range. Traverse measurements and

metal temperatures of the combustors and

transition ducts were taken at several points

in the load range. Figure 15 shows the

traverse at entry to the nozzle guide vanes.

Emission measurements of NOx and CO have also

been taken at several load conditions. With

water or steam injection the levels of No can

be significantly reduced as shown by Figure

16. Levels of CO rise with increased water

injection rates and an optimum water fuel

ratio is found to be around 0.7:1.

Package and System Tests

The Typhoon has also been tested, on a

development basis, against a generator, as

shown in Figure 17, to allow the control

zw system to be finely tuned. The test facility

has the ability to apply or reject the full 4

MW block load thereby allowing the response of

wxcv the engine to be established. Figure 18 shows

a typical recovery following a full load

rejection. The speed change is noted to be

within the 4% droop of the governor and the

recovery within one second interval.

Other features tested during the package

development are the systems including lub oil,

fuel, starting, fire and gas and acoustic

COMBUSTERS enclosure.

Cyclic Endurance

Having established that the engine per-

forms to specification the ultimate test is

to simulate field operation via an accelerated

cyclic programme. The severity of the cyclic

programmes are devised to reduce the test

time. In this particular case the number of

transients which the engine has been subjected

to is considered to be equivalent to 40,000

hours field operation for a typical

installation.To provide information

stability and other major

simple cycle, as shown in

applied. This cycle entails

speed with a rapid application

The engine is then allowed

minutes at full temperature

down and being spun at relatively

quench the engine.The cycle shown in Figure 19b has been

devised, principally, to thermally cycle the

hot end of the engine including combustor,

turbine blading and stator support systems.

This cycle commences in a similar manner to

the first with a start to full speed and a

rapid load application. Following the initial

warm up half load changes are carried out to

simulate large electric motors being brought

on line.

These two cyclic programmes were carried

out on core 3 over a four month period with

the final tally as shown in Table 2. 

The stripdown of the engine following the

endurance programme revealed the engine to be

in excellent condition. Figure 20 shows some

of the components following the stripdown.

The only area to show some distress was a

honeycomb tip rim seal which had sections of

fatigued honeycomb due to the proximity of the

seal track relative to the edge. In this case

the solution was to re-position the seal

slightly downstream.

Following the endurance programme the

engine has been rebuilt with all the original

parts including the honeycomb seal and was

subsequently used for the package tests.