What is a single spool turbojet engine?
“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 single spool?
A single spool core means that all rotating components in the compressor and the gas generator are on one shaft and rotate at the same speed. In contrast, a dual spool core splits the compressor into two independently spinning rotors that are each powered by a separate gas generator turbine on concentric shafts.
How many spools does a turbojet have?
The hot gas generator employs two spools, like the turbojet shown in figure 10.1(a), and a third spool that is independent of the other two contains the fan and its own turbines. Fans of more than one stage have also been used, as have aft-mounted fans.
What are the advantages of a two spool over a single spool engine?
A Two-Spool Engine The reason for doing this is that the low-pressure stages are larger in diameter, so they have higher tip speed for a given rotational speed. At the same time, the temperature is lower, and so too is the speed of sound. So, to keep the flow subsonic, they are designed to rotate at a slower speed.
What is engine spool up?
Jet engines require time to accelerate, so the increase in thrust (known as spooling up) improves the ability to go around should it be necessary. Jet engines (U.S. certified) can require up to eight seconds to accelerate from idle to maximum thrust.
What is twin spool?
A twin spool design normally has the front compressors attached to the rear turbines using an inner shaft, with a higher pressure compressor and a higher pressure turbine connected with an outer shaft.
What is the purpose of a spool?
The function of the spool is to move within the sealed case and provide the function of either blocking or opening these ports depending on the position of the spool.
Are turbojets still used?
Turbojets were used on Concorde and the longer-range versions of the TU-144 which were required to spend a long period travelling supersonically. Turbojets are still common in medium range cruise missiles, due to their high exhaust speed, small frontal area, and relative simplicity.
What is the purpose of the diffuser section in a turbine engine?
Diffuser is one key component of the gas turbine combustor following the compressor. Its primary function is to slow down the air flow delivered by the compressor in order to promote efficient combustion and avoid large total pressure losses.
How do spool valves work?
Spool valves regulate the flow of fluid in hydraulic systems. Spool valves would slide backward and forward so that the fluid flow can be either in one direction or another around a circuit of pipes. Spool valves have two basic components, a cylindrical barrel in which slides a plunger or spool.
What’s the difference between a single spool and two spool jet engine?
A single spool jet engine is what is known as a turbojet engine. They have a single compressor rotor drum and its associated turbine. A two spool engine is what we call a low bypass ratio engine where you have two compressor stages.
What is the speed of a twin spool engine?
In a twin spool engine, the two shafts are known as low pressure compressor and high pressure compressor . The speed of low pressure compressor is denoted by N 1. The speed of high pressure compressor is denoted by N 2. In a typical twin spool jet engine the low pressure spool spins ( specially the compressor and turbines ) at a rpm of 9000.
How is a turbojet engine connected to a propeller?
The power turbine is connected to a propeller by means of a reduction gear. This system takes advantage of the relatively high efficiency of the propeller and the smoothness and light weight of the turbojet engine. In this configuration the thrust provided by the turbojet core engine is almost entirely used to drive the propeller.
How much does it cost to make a turbojet engine?
Although commercial and military jet engines are extremely expensive, a simple turbojet engine can be constructed utilizing a used turbocharger and other readily obtainable parts. The total cost should not exceed $500.00. No special skills or engineering knowledge are required, however they help.