Why LPT has more stages than HPT?
One of the reasons the low pressure region has more stages is because you want to avoid flow separation which cause a loss of energy to recirculation instead of providing thrust or power. The low pressure region is compressing; this causes an adverse pressure gradient.
How many stages are there in LP turbine?
Each LP Turbine (low-pressure turbine) is usually double-flow reaction turbine with about 5-8 stages (with shrouded blades and with free-standing blades of last 3 stages). LP turbines produce approximately 60-70% of the gross power output of the power plant unit.
Why LP turbine is double flow?
In a double flow rotor, the blades in each half face opposite ways, so that the axial forces negate each other but the tangential forces act together. This design of rotor is also called two-flow, double-axial-flow, or double-exhaust. This arrangement is common in low-pressure casings of a compound turbine.
What is HP and LP turbine?
HP and LP refer to ‘High-Pressure’ and ‘Low-Pressure’ shafts, and speeds. The pressures are “relative” pressures, one turbine operating at a higher pressure than the other, which is called the “low pressure” turbine (shaft). Some GE-design gas turbines have multiple shafts that spin at independent speeds.
What makes up the core of a turbofan engine?
In the turbofan engine, the core engine is surrounded by a fan in the front and an additional turbine at the rear. The fan and fan turbine are composed of many blades, like the core compressor and core turbine, and are connected to an additional shaft.
Why do un geared engines have more LP turbines?
The LP rotor of an un-geared engine runs at the same rotational velocity as the fan. Its optimal RPM for the turbine may be higher, and that can be accommodated by the geared fan.
Why are turbofan engines more fuel efficient than turboprops?
Because the fuel flow rate for the core is changed only a small amount by the addition of the fan, a turbofan generates more thrust for nearly the same amount of fuel used by the core. This means that a turbofan is very fuel efficient. In fact, high bypass ratio turbofans are nearly as fuel efficient as turboprops.
What kind of blades are in a turbofan engine?
The fan and fan turbine are composed of many blades, like the core compressor and core turbine, and are connected to an additional shaft. All of this additional turbomachinery is colored green on the schematic. As with the core compressor and turbine, some of the fan blades turn with the shaft and some blades remain stationary.