LM 6000 Dual Compressor


Thread Starter


Can anyone briefly describe why we use LP and HP compressor and LP and HP turbine in LM6000?

I want to preface this by saying I'm not very familiar with the LM6000 engine or packages, of which there are several. But, this is my understanding based on limited exposure and experience with a couple of LM6000 packages.

The LM6000 is an aircraft derivative unit, meaning that the "gas generator" (GG) section of the unit is exactly what you would find on the wing of many airplanes. The GG is where the fuel is combusted to produce the hot combustion gases that are then expanded through turbines--or on many aircraft engines--used to produce thrust to propel the airplane.

This GG section is then bolted to a power turbine--usually called the LP turbine, because the pressure of the hot combustion gases entering the LP turbine section is the lowest in the unit.

The GG of the LM6000 is a dual-shaft gas turbine. Why? Because the designers determined that this was necessary to optimize the power-to-weight ratio of the GG section. The two shafts rotate at different speeds independently of each other. There are two turbine sections, each connected to a compressor. <i>When one is speaking ONLY about the GG section, there is an HP and an LP.</i> When one is speaking about the entire LM6000 unit, including the power turbine, the LP section of the GG is re-termed to be the IP section of the unit (the GG and power turbine).

As for why the GG has two compressors--again, that's a design consideration and was likely chosen to be able to flow the most air into the HP axial compressor.

Hope this helps!

Hashem Alkhasawneh

I can add one point....In case of dual shaft gas turbine the start up system will be more simple and small because you just want to rotate the light shaft (HP). In many application or location will not be easy to have a big and strong starter like big starter motor what will be heavy and need big place and also need to much power. But in case of dual shaft Aeroderivative, gas turbine may be a simple pneumatic or hydraulic starter will be enough to start your turbine. So that will help you if you have shortage in the space or shortage of power available so it will be much better for black start as well. and this will be very useful in offshore application or aircraft application. other reason is when you have two shaft your control will be better against the ambient temperature variation.