Turbofan Engine: Working Principles, DIY Builds, and Common Uses

Have you ever wondered what makes the jets fly over the skies carrying heavy loads? Well! The secret lies in Turbofan engines. You can find turbofan engines from commercial airliners to military fighters, which makes them an integral part of modern aviation.

If you are an aspiring engineer or just curious, learning about the working principles of a turbofan jet engine can lead to innovative ideas. In this article, we’ll discuss what turbofan engines are, their features, the working principle, and common uses. Plus, we’ll also provide simple instructions for making a useful working model at home. So, come with us!

1) What is a Turbofan Engine?

A turbofan engine is a jet engine that uses a turbine to drive a fan, so that part of the air is directly discharged through the outer duct to generate thrust, and the other part of the air enters the inner duct to participate in combustion and work, thereby improving the efficiency and thrust of the engine.

It is mainly composed of the following parts: air inlet, fan, compressor, combustion chamber, turbine, tail nozzle. In addition to the above main components, the turbofan engine also includes auxiliary systems such as fuel system, lubrication system, control system, etc. to ensure the normal operation and performance optimization of the engine.

This makes it an extremely powerful air-breathing engine and provides a high thrust (the force which propels the aeroplane forward) to weight ratio, higher efficiency and quieter operations.

For this reason, it is mainly deployed for commercial and cargo aeroplanes and even military fighter jets.  Now, let us analyse some of the critical factors that enhance the fuel efficiency and usability of Turbofan engines in the real world!

• Key Features of a Turbofan Engine

• Dual Stream Configuration: A turbofan engine has two air streams in operation. The first one involves the core driving primary airflow, which moves through the engine to generate thrust. The second one is the bypassing secondary airflow, which does not aid in providing thrust but bypasses the core.  

With this dual stream arrangement, the power of the engine is increased while the power-to-weight ratio of the engine is very high.  

• Noise Reduction Features: Like all other machines, turbofan engines include features which seek to reduce the noise produced when an aircraft is in operation. They use smooth fan blades with chevron nozzles, which reduce noise. As a result, the takeoff noise is usually below 85 db.

• Consistent Power Throughout Flight Operations: Moreover, turbofan engines provide constant and reliable thrust from takeoff to landing while sustaining dependable thrust in every phase of flight. They adjust fuel and airflow in real-time, which ensures smooth climbs, stable flight, and safe descents while reducing issues with weather.

• Advanced Surveillance and Control Systems: Lastly, modern turbofan engines are under the control of FADEC systems, which adjust performance based on fan speed and temperature. This system optimally enhances safety and reliability while minimising failures, supporting scheduled maintenance, and sustaining robust engine operation.

2) How a Turbofan Engine Works?

A turbofan engine incorporates the principles of Newton’s 3rd Law of Motion (for every action there exists an equal and opposite reaction) and Bernoulli's (air speeds up as it exits, pressure decreases) principles of physics. Likewise, in a turbofan engine, thrust is created by the expulsion of exhaust gases in equal and opposite reaction.

In addition, Bernoulli’s principle helps in the acceleration of exhaust gases, and thus, effective thrust generation is achievable. However, understanding the workings of a turbofan engine requires knowing the major components first. Therefore, let’s take a closer look at those parts.

• Parts of a Turbofan Engine

• Fan: It consists of huge rotating blades which handle the pulling of air backwards or dividing it into bypass and core streams to maximise thrust and efficiency.

• Compressor: Consists of rotor and stator blades, which compress air to increase its pressure for more efficient combustion.

• Combustion Chamber: Compressed air is injected into a fuel line, then ignited to create high-energy gases.

• Turbine: Usually blades mounted on a shaft which extract energy from exhaust gases to turn the fan and compressor, automatically igniting.

• Nozzle: A hollow, tapered tube designed to accelerate exhaust gases above the frictional minimum velocity.

• Bypass Duct: Serves to reduce operational fuel consumption and decrease noise.

• The Working Process (Step-by-Step)

Step 1: Air Intake

The fan has a remarkable ability to capture great amounts of air, which is then split into two streams. One of the streams goes through the engine core while the other stream bypasses it.

Step 2: Compression  

After this, the compressor processes the core's air by moving it with the aid of rotating blades, which squeeze the air, increasing its pressure. This added pressure of fuel is used in the next stage, which is fuel combustion.  

Step 3: Fuel Combustion  

Inside the combustion chamber, the high-pressure air mixes with fuel and ignites. The explosion of the fuel-air mixture generates high-temperature, high-pressure gases, which expand rapidly.

Step 4: Turbine Action  

Now, gas flows without obstruction into the turbine, granting freedom to spin. The turbine receives the gas and is spun, and the exhaust gas will consume the turbine’s energy and extract energy.  

Step 5: Exhaust and Thrust Generation  

Finally, the hot gas, which is rotating the turbine at last, is still allowed to pass from the nozzle. The nozzle releases the gas at high acceleration, enabling the formation of air jets and then gives vibration in action, thrusting the aeroplane forward.

3) Turbojet vs Turbofan vs Turboprop: What's the Difference?

To help you appreciate the various aircraft engines, let us now discuss the differences between Turbojet, Turbofan and Turboprop engines.

4) What are the common uses of a Turbfan engine?

Due to their reliability, power and efficiency, turbofan engines have found applications in air transport, both commercially and in military use. Let us break down their functionality and impact on various sectors of aviation:  

• Commercial Airliners  

In commercial aviation, turbofan engines dominate long-range flights with large airliners such as the Boeing 777 and Airbus A380. These engines are optimised for cruising at 35,000 to 40,000 feet and supporting propulsion needs of 900 km/h (560 mph) cruise speed.

Moreover, because of their high bypass ratio, turbofan engines are fuel efficient, which is a necessity for airlines operating on long-haul routes due to operating expenses. This also maximises profits while being environmentally friendly.

• Cargo Planes

Furthermore, in the case of cargo planes like Boeing 747 Freighter, turbofan engines are equally important. These engines enable cargo aircraft to fly at high altitudes and cover great distances, ensuring that goods are delivered on schedule all over the world.

Just like commercial airliners, these engines help cargo planes lift huge payloads with fuel efficiency, even during soak periods. This economic power helps logistics companies meet deadlines while minimising costs.  

• Military Aircraft  

In military aviation, turbofan engines are no less important. F-22 Raptor and KC-135 Stratotanker are examples of aircraft that depend on a swift jet engine. With thrust capabilities between 20,000 and more than 100,000 pounds, military jets are able to perform high-speed combat missions and drag a plane jet for aerial refuelling.

• Private Jets

Additionally, Turbofan engines are also widely used in luxury privately-owned jets, like Gulfstream G650, in addition to commercial and military applications. As turbofan engines are quiet and reliable, they have become a necessity for people who require high standards in their private travels.

5) How to build a Turbofan engine? A DIY Guide

Creating a working model of a turbofan engine may indeed require complexity, but with the right materials, tools, and information, this task can be made quite simple; for instance, DIY turbofan engine kits provide all the required parts to assemble a simple model.  

In this part of the guide, I’ll give a concise and logical explanation of how to assemble the model of a DIY turbofan engine kit, and I hope you all find it useful.

• Basic Materials in a DIY Turbofan engine model Kit:

• Fan Blades: Simulate the rotation that pulls in air.

• Electric Motor: Drives the rotation of the fan blades

• Battery: Usually 9v or AA for the required electric current.

• Casing: Contains and holds the parts together.

• Compressor Blades: Optional, to replicate the air compression process.

• Exhaust Nozzle: Outlets and quickens thrust air.

• Wires: For connecting the engine and power supply.

• Mounting Set: Holds parts in fixed positions.

• Step-by-Step Construction Procedure

Step 1: Unbox your DIY Kit

The first step consists of listing all the components. You can match pieces within the kits, and taking inventory of each helps you name different parts. From here, we can proceed to the motor, the battery, the blades and casing, which are critical to the function of  Turbofan.

Step 2: Attach the Motor to the Fan Blades

Now, join the electrical motor with the fan blades. This step matters as the motor is going to spin the fan blades. For the first step in the engine's operation, the powered fan blades will simulate the intake of air.

Step 3: Incorporate the Component of the Engine

After securing the electric motor with the blades, insert the parts into the casing. Tighten the motor along with the fan using the mounting set, as the engine structure needs to hold firmly. The engine can now function without issues as the critical outer frame is put together.

Step 4: Install the Compressor Section

If your kit includes compressor blades, ensure to install them after the fan blades. These blades serve to better simulate the process which involves the compressing of air to increase its pressure.

Step 5: Fix the Exhaust Nozzle

In this stage, it is possible to fix the exhaust nozzle at the rear of the casing. The function of the nozzle is very important because it permits control of the exhausted air, thus simulating the thrust production. Depending on your kit, you may have some options for modifying the nozzle's diameter and thereby affecting airflow rate.

Step 6: Join the Motor to the Battery

All the wires are now attached to the battery and the motor. Position the battery where it can be easily turned on and off, the toggle should be easy to reach. The engine should already have been fixed in place on the chassis. You can turn on the power supply in this position to work on powering the Turbofan.

Step 7: Conduct Troubleshooting and Testing Tasks

Now, you have to to check all the operations. Make sure that the throttle is lifted before the vehicle starts the move. To cut inflow, place a thin sheet of paper which helps to cut into a concentrated measure while not fully blocking airflow. Cover the system’s air inlet while strategically adjusting the diameter of the controller's air exhaust.

Step 8:  Lastly, check that each part is aligned to make certain that the engine is stable. If the motor or fan blades feel wobbly, then take the steps to tight them securely within the casing.

If you wish to foster your creativity and want to create a working model of a turbofan engine at home. Then look no further than EngineDIY, we offer DIY kits of various engines, including Turbofan, Sterling engine and many more at affordable prices. So, contact us today!

6) Final Words

In short, Turbofan Engines are a beautiful mix of technology and innovation, used in aircraft, taught in engineering, and much more. To all enthusiasts, if you wish to create your very own model, there are plenty of DIY kits available at EngineDIY that cater to the inner mechanic in you.

Assembling a DIY kit promotes working with highly detailed components and direction manuals, which makes grasping the ideas that drive turbofan engines not just straightforward, but fun.

8) FAQs

i) What is the lifespan of a turbofan engine? 

With routine upkeep, a turbofan engine can have remarkably long flight hours, ranging anywhere from 20,000 to 30,000. Optimized performance rests heavily on periodic maintenance and overhauls.  

ii) What are the environmental impacts of operating a turbofan engine?

Turbofan engines, although more efficient than turbojets, still contribute to carbon emissions. Newer technologies focus on reducing emissions while increasing fuel efficiency, noise levels, and the overall environmental impact.

iii) What are the benefits of using turbofan engines in commercial aviation?  

Turbofan engines are the lead choice to be used in commercial aviation due to greater fuel efficiency, quieter operation, higher thrust-to-weight ratio, and reduced emissions all boasting their commercial strategic aviation advantages.