The Evolution of Jet Engines: Efficiency and Power

🔧Jet engines have evolved to become more efficient and powerful over the past 50 years.

🌬️Turbofans with low bypass ratios are commonly used in fighter jets to improve cruising efficiency and increase range.

🚀Moving more air or moving the air faster can increase the thrust and efficiency of jet engines.

🔄Modern engines use multiple compressor and turbine wheels to increase efficiency by operating at different speeds.

🚁Counter-rotating shafts in some engines cancel out gyro effects, improving maneuverability at low speeds.

What is the main difference between turbojets and turbofans?

—The main difference is that turbojets rely on the jet of expanding gases for all the thrust, while turbofans have some of the air bypassed around the engine, reducing fuel consumption and noise.

How do bypass ratios affect engine performance?

—Bypass ratios indicate how much air bypasses the engine core. Higher bypass ratios, like in commercial turbofans, improve efficiency and reduce fuel consumption, while lower bypass ratios, like in low bypass turbofans, provide more thrust but lower fuel efficiency.

What is the advantage of using multiple compressor and turbine wheels?

—Multiple wheels allow each wheel to operate at its peak efficiency, increasing overall engine efficiency and power. They also help in a more incremental increase of pressure.

Why do some engines have counter-rotating shafts?

—Counter-rotating shafts cancel out the gyro effects of the engine, improving maneuverability at low speeds and reducing resistance to changes in aircraft position.

How do low bypass turbofans achieve higher thrust?

—Low bypass turbofans achieve higher thrust by moving the air faster rather than moving more air. This is achieved by increasing the temperature of the exhaust gases through the use of afterburners.

00:00Introduction to the evolution of jet engines and comparison to piston engines.

01:35Explanation of why some air is bypassed around the engine in turbofans.

03:30The concept of moving more air or moving the air faster to increase thrust and efficiency.

05:06Comparison of high bypass and low bypass turbofans, with a focus on low bypass turbofans.

06:28The limitations of moving more air and the advantages of moving the air faster.

07:34The use of afterburners in low bypass turbofans to achieve supersonic speeds.

08:32The efficiency benefits of two shafts and multiple compressor and turbine wheels in modern engines.

09:43The use of counter-rotating shafts to cancel out gyro effects and improve maneuverability.