BACKGROUND OF THE INVENTION

This application relates to a geared turbofan gas turbine engine, wherein the low and high pressure spools rotate in the same direction relative to each other.

Gas turbine engines are known, and typically include a fan delivering air into a compressor section, and outwardly as bypass air to provide propulsion. The air in the compressor is delivered into a combustion section where it is mixed with fuel and burned. Products of this combustion pass downstream over turbine rotors, driving them to rotate. Typically there are low and high pressure compressors, and low and high pressure turbines.

The high pressure turbine typically drives the high pressure compressor as a high spool, and the low pressure turbine drives the low pressure compressor and the fan. Historically, the fan and low pressure compressor were driven at a common speed.

More recently, a gear reduction has been provided on the low pressure spool such that the fan and low pressure compressor can rotate at different speeds. It desirable to have more efficient engines that have more compact turbines to limit efficiency loses.

SUMMARY

In a featured embodiment, a gas turbine engine turbine comprises a high pressure turbine configured to rotate with a high pressure compressor as a high pressure spool in a first direction about a central axis. A low pressure turbine is configured to rotate in the first direction about the central axis. A fan is connected to the low pressure turbine via a gear reduction and will rotate in the first direction. The engine is configured to have a ratio of a thrust provided by the engine, to a volume of a turbine section including both the high pressure turbine and the low pressure turbine, that is greater than or equal to about 1.5 and less than or equal to about 5.5 lbf/in3. The thrust is sea level take-off, flat-rated static thrust.

In another embodiment according to the previous embodiment, guide vanes are positioned upstream of a first stage in the low pressure turbine to direct gases downstream of the high pressure turbine as the gases approach the low pressure turbine.

In another embodiment according to any of the previous embodiments, a mid-turbine frame supports the high pressure turbine.

In another embodiment according to any of the previous embodiments, the guide vanes are positioned intermediate the mid-turbine frame and the low pressure turbine.

In another embodiment according to any of the previous embodiments, there is an intermediate section, and the intermediate turbine section drives a compressor rotor.

In another embodiment according to any of the previous embodiments, the gear reduction is positioned intermediate the fan and a compressor rotor driven by the low pressure turbine.

In another embodiment according to any of the previous embodiments, the gear reduction is positioned intermediate the low pressure turbine and a compressor rotor driven by the low pressure turbine.

These and other features may be best understood from the following drawings and specification.

