Table of Contents
Why are there 3 spool engines?
Advantages of a 3-spool engine Allows for higher ratios of fan airflow to engine flow. This allows for increased thrust without a corresponding increase in jet velocity and reduction in propulsive efficiency leading to high SFC.
What are the 5 major sections in a turbofan engine?
Turbojets work by passing air through 5 primary sections of the engine:
- Step 1: Air Intake. The air intake is essentially a tube in front of the engine.
- Step 2: Compressor.
- Step 3: Combustion Chamber.
- Step 4: Turbine.
- Step 5: Exhaust (aka “I’m outta here!”)
How does a turbo shaft engine work?
As a variation of the gas turbine, turboshafts are very similar to turbojets. The operating principle is identical: atmospheric gases are ingested at the inlet, compressed, mixed with fuel and combusted, then expanded through a turbine which powers the compressor.
What is the principle of turbofan engine?
A turbofan engine, sometimes referred to as a fanjet or bypass engine, is a jet engine variant which produces thrust using a combination of jet core efflux and bypass air which has been accelerated by a ducted fan that is driven by the jet core.
What is a spool shaft?
“Spool” is engineering shorthand for the combination of an engine compressor and high-pressure turbine that drives it using a connecting drive shaft. In a single-spool engine, the high-pressure turbine drives the entire compressor.
What is the rpm of a 747 engine?
On large modern airliners, the jet engine fan runs at between 2500 and 4000 RPM. However, some parts of the engine spin many times faster….Examples of Jet Engine RPM.
| Engine Model | RPM | Application |
|---|---|---|
| Rolls-Royce RB211 | 3900 / 4500 RPM* | Boeing 747-400, 757, and 767 |
What drives the fan in a turbofan engine?
The fan (and booster stages) are driven by the low-pressure turbine, whereas the high-pressure compressor is powered by the high-pressure turbine.
Why are turbofans more efficient?
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 is the bypass ratio in turbofan?
Description. In a turbofan (bypass) engine, the bypass ratio is a comparison between the mass flow rate of air drawn into the engine through the fan disk that goes around the engine core with the mass flow rate of the air that goes through the engine core.
How much shaft play should a turbo have?
While there is always going to be shaft play in a journal bearing turbo, the allowable tolerances we’re talking about is 0.003″-0.010″ which isn’t much to really notice. If you have 0.020″ of shaft play, the bearings are worn and it’s going to wear at a much faster rate as opposed to bearings that are within tolerance.