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The DR-61 was developed as an efficient, cost-effective, and reliable power turbine for the GE LM2500 gas generator. The DR-61 is an industrial, heavy duty, mechanical drive turbine with an output shaft design speed of 5500 rpm. The LM2500 is an industrial derivative of the CF6 high efficiency turbofan engine installed on wide body commercial aircraft.
The DR-61 is a two-stage power turbine that is bolted rigidly to the LM2500. The resulting short power turbine inlet diffuser reduces the total pressure loss and improves overall efficiency. To avoid thermal distortion, which can lower efficiency, all turbine casing components are symmetrical, unsplit rings from the gas generator discharge to the power turbine diffuser exhaust.
The two-stage rotor has cooled discs and tip shrouded blades for durability. In addition, the tip shrouds run against abradable honeycomb seals in the casing to minimize leakage and improve efficiency. All elements of the rotor have been designed for a creep life of over 100,000 hours at full load. The materials utilized are modern super-alloys specifically developed for service at the temperatures encountered.
The power turbine shaft is designed to insure the first bending critical speed of the rotor is well above the maximum operating speed. The shaft is supported in two tilting pad journal bearings. A tilting shoe thrust bearing in mounted in the same housing as the aft journal bearing.
An optional shaft driven accessory gearbox can be provided which is bolted to the coupling end on the bearing housing. The gearbox has three shafts that can be used for oil pumps or other accessory drives. The DR-61 package can be supplied with either a standard combustion system or a GE Dry Low Emissions system designed to reduce the amount of NOx, CO, and unburned hydrocarbons in the exhaust.
DR-61 Design Summary
Package
- GE LM2500 gas generator
- DLE or standard package
Power Turbine
- Heavy duty industrial design
- Oil film bearings
- Two-stage overhung rotor
- Tip shrouded blades
- Design life of 100,000 hours
DR-61 Performance Summary
| Design Speed: | 5,500 RPM |
| Maximum Continuous Speed: | 5,775 RPM |
| Power: | 31,000 HP 23,100 KW |
| Efficiency: | 37.5% |