An In-Depth Overview of Turboshaft Engines: Principles, Components, and Applications

Turboshaft Engine Introduction

The turboshaft engine is the engine that produces the power of the shaft to run the machine instead of generating thrust to fly the aircraft. The turboshaft engine is common in small applications, for example, helicopters and other power units.

To produce the energy for the aircraft engine, the turboshaft uses the same principle which turbojet used to fly the aircraft, and the compressor will be incorporated.

The prime difference between a turbojet engine and a turboshaft engine is that it has a power av section. Additionally, it consists of an output shaft and turbine, which have been incorporated into the design.

Turboshafts Engine

Engines like the turboshaft are the same as turbojet engines and also, it is similar to turboprop engines, but there are a few differences between them. The heat gets pill from the exhaust and then transferred into the shaft of the output.

Many cases have been seen where the power turbine is not mechanically linked with the generator gas. This “free power turbine.” Permit the speed of the power turbine to be optimized for each entry, which will energize without any help from the reduction gearbox which is in the engine.

The power turbine removes most energy from the steam exhaust and transfers it to the output shaft.
The engine of the turboshaft is the same as the engine of the turboprop, and variants of these aircraft are available with many engine types.
From a turbine, a turboshaft engine is formed, which is gas-powered, and the turboprop engine operates the same as it also operates.

Propellers can’t be operated by the turboshaft engine it is used to provide or to generate the power to the rotor which is used in the helicopters.

The engine turboshaft is designed in such a way that it makes rotor speed rotate independently of the speed of the generator gas.
It will help the helicopter or make it capable of maintaining or managing the speed of the rotor constantly even when the speed of the gas generator is declined.
Generally, in helicopters, engines like the turboshaft are used most of the time. When the topic is on the difference between the turbojet engine and turboshaft engine, the difference is that the power used by the turbojet engine is used to turn the turbine instead of generating or producing force.
Both the turboshaft engine and turbojet engine are similar to each other, but the turbojet engine has a shaft that is long that connects to the front and the rear/backside.
Most of the engines which are used in the helicopter engine are turboshaft engines whose shaft is connected with the transmission of the rotor blades of the helicopter.
The components or the parts which are used in the engine of a turboshaft are mostly of turbojet engines or otherwise; it is similar to turbojet engines. The shaft gets fitted with the turbine, which will provide the power or energy to the transmission of the blade of the rotor.
Transmission of the rotor blade works to transfer the shaft rotation to the rotor blade. Piston engines are a little bigger than those turboshaft engines, but the weight of the turboshaft engine is higher than the weight of the piston engine.
The Turboshaft engine gear system, which is on the downside, is breakable easily.

These turboshaft engines are used by helicopters; the difference between turbojet and turboshaft engines is that they(turboshaft) engines use most of the power to turn the engine turbine instead of generating thrust.

Many people have questioned why turboshaft engines are used in helicopters. The answer is that the engines, which are light in weight, small engines like gas turbines, generate more power than engines like pistons, and that’s why these helicopters are capable of lift.

How Does a Turboshaft Engine Work?

The main function of the engine turboshaft is to produce shaft power. In a complex machine like a helicopter, the shaft engine produces the shaft power required to run the rotor.

The power shaft which will turn the engine rotor will receive power from the set of turbines. The turbine’s energy is absorbed by hot and high-pressure gas flowing over the blades.

The technology of the airfoil allows the turbine to turn the blade.
To guide the flow of the set of stator blades properly, they are fixed to
Engine cover. These stator blades also confirm whether sufficient velocity flow is maintained or not in the turbine row inlet.
Many of you think that how that high-energy gas gets generated is too simple: this high energy gets generated in the combustion chamber.
The fuel formed is mixed with medium temperature and high-temperature air.
A set of compression stages produces this air; after this, you can see that the compressor is fitted on the hollow shaft, which is not connected to the power shaft.
For the operation, the compressor requires energy; the energy which is required is provided by the set of new turbines which gets fitted on the same shaft hollow; the purpose behind the installation of a new turbine is to provide or supply energy to the compressor which is referred to as the turbine of the gas producer.
This process shows how the Gas turbine unit and power turbine unit rotate independently with the help of a coaxial shaft; that’s why synchronization of the combustion chamber compressor and turbine produces the necessary power output.
The centrifugal compressor gets introduced at the compressor section to compress the gas effectively.
These are the basic parts and workings of the turboshaft engine.
Principle of turboshaft engine
Jet engines are also known as gas turbine engines; they work on the same principle on which turboshaft engines work.
The aircraft engine sucks surrounding air into the engine at the front with the fan. The gas which burns expands and then blasts through the nozzle on the rear side of the engine.
As the jet engine leaves the gas in a backward direction, the aircraft engine thrusts the aircraft to fly in the forward direction.
Hot or warm air moves towards a nozzle and passes from another set of blades known as turbines.
The shaft on which the compressor is attached is the same shaft on which the turbine is also attached; as the turbine spins, the compressor also spins.

How Does Rotor Get Power from Engine of Aircraft?

With the help of the main Gearbox, power is transferred from the engine to the rotor that will change the power from the engine and send it to the transmission. After this process, RPM gets reduced in the transmission from 1000 TO 100 RPM, and the torque will increase.

The transmission will drive a stick that will give the rotation directly to the rotor in the engine. Again and again, the shaft will come out from the transmission to drive directly to the rotor tail.

Turboshaft Engine Stages

Combustion Chamber
Turbine
Nozzle
Gas Compressor
Gear Box

#1. Combustion Chamber

The internal energy of the gas increases due to the combustion process, which will then translate into an increase in pressure, temperature, and volume, which is dependent on the configuration.
Example: Combustor of a jet engine.
Pressure gets controlled, and it creates combustion, and volume increases.
Pressure increases, and it will use volume to do work.
In case the velocity of the gas changes, thrust gets generated.
Such as in the nozzle of the aircraft engine.

#2. Turbine

In simple language, a turbine is a turbo machine with one working part. That part is known as the rotor, which is also known as the shaft or drum, with the attached blades.

#3. Nozzle

The nozzle is the type of device which is made or designed to control or drive the direction/ characteristics of the flow of fluid as it exists with chambers that are enclosed or pipes.
Nozzles are frequently used to control the flow rate, mass, direction, speed, shape, and emerging steam pressure.
The velocity of the fluid increases in the nozzle at the expense of energy pressure.

#4. Gas compressor

The gas compressor is the device, or we can say that it is the mechanical device that increases the gas pressure by reducing the

volume. Compressor air is nothing but a specific type of compressor gas.

#5. Gear Box

The Gearbox is a type of transmission. This transmission is the machine that consists of a power source and system of power transmission in the Gearbox. Commonly, the transmission term is referred to as Gearbox.

The Gearbox used the gears and train gear to generate or produce the speed and the torque, which converted from a rotating power source to a different or another device.

Advantages and Disadvantages of Turboshaft Engine

Advantages of Turboshaft Engine

Turboshaft has a simple design, making it reliable and easy to service compared to piston engines.
Turboshaft is simple to control
The compressor has an available supply of air
The rate of specific weight is lower.
The rate of oil consumption in turboshaft engines is very low.

Disadvantages of Turboshaft Engines

Required high power while starting.
The manufacturing cost for the turboshaft engine is very high.
When the turboshaft engine is in low air, the fuel consumption is high.
Because the turboshaft has a low power level, there are inefficient operations.

Frequently Asked Questions (FAQ) about Turboshaft Engines

What is a turboshaft engine?

A turboshaft engine produces shaft power to run machinery rather than generating thrust to propel an aircraft. It is commonly used in applications like helicopters and other power units.

How does a turboshaft engine differ from a turbojet engine?

The primary difference is that a turboshaft engine has a power turbine section that extracts energy from the exhaust gases to drive an output shaft, while a turbojet engine uses exhaust gases to produce thrust.

How does a turboshaft engine work?

A turboshaft engine works by using hot, high-pressure gases from a combustion chamber to turn turbines. These turbines then drive an output shaft that provides mechanical power to run a rotor or other machinery.

What are the main components of a turboshaft engine?

The main components include the combustion chamber, turbine, nozzle, gas compressor, and gearbox.

Why are turboshaft engines commonly used in helicopters?

Turboshaft engines are lightweight, compact, and capable of generating more power than piston engines, making them ideal for helicopters which require high power for lift and maneuverability.

What are the advantages of turboshaft engines?

Advantages include a simple design, reliability, ease of service, low specific weight, low oil consumption, and simple control.

What are the disadvantages of turboshaft engines?

Disadvantages include high power requirements during startup, high manufacturing costs, high fuel consumption at low airspeeds, and inefficient operation at low power levels.

How is power transferred from the engine to the rotor in a helicopter?

Power is transferred from the engine to the rotor through the main gearbox, which reduces RPM from around 1000 to 100 and increases torque. The transmission then drives the rotor directly.

Can a turboshaft engine be used to operate propellers?

No, turboshaft engines are not used to operate propellers. Instead, they generate power for rotors, as seen in helicopters.

What is a “free power turbine” in a turboshaft engine?

A free power turbine is not mechanically linked to the gas generator. This allows the power turbine’s speed to be optimized for various applications without being dependent on the gas generator’s speed.