🤖 AI Summary
Overview
This episode dives into the fascinating engineering behind jet engines, exploring how they operate at temperatures exceeding the melting points of their materials. It unpacks the physics, materials science, and manufacturing innovations that make modern jet engines possible, focusing on turbine blades and their ability to withstand extreme conditions.
Notable Quotes
- To keep a turbine blade whole and unaffected within an engine is like putting an ice cube inside your oven, turning it up to max, leaving for work, and coming back after an eight-hour shift to find it still frozen.
– Rolls Royce Engineer, on the challenge of turbine blade durability.
- You're always on a knife edge, pushing every material, every process to the limit to build an engine that can do the seemingly impossible—run hotter than its own melting point.
– Derek Muller, on the ingenuity of jet engine design.
- Frank, it flies!
– That was bloody well what it was designed to do, wasn’t it?
– Frank Whittle, on the first successful jet engine flight.
🚀 How Jet Engines Work
- Jet engines operate by compressing air, mixing it with fuel, and igniting it to produce high-pressure, high-temperature gas.
- The turbines extract energy from this gas to power the engine's fan and compressors, with the fan generating 80% of the thrust.
- Efficiency is achieved by pushing large volumes of air backward at low velocity, minimizing wasted energy.
🔥 The Extreme Environment Inside Jet Engines
- Combustion chambers reach temperatures of 1500°C, far beyond the melting points of most metals.
- Turbine blades endure immense stress: spinning at 12,500 RPM, with forces equivalent to 20 metric tons pulling on each blade.
- Dust and pollutants in the atmosphere exacerbate wear by clogging cooling systems and eroding protective coatings.
🧪 Materials Science: Nickel Superalloys and Gamma Prime
- Early jet engines used steel, but modern engines rely on nickel superalloys, which maintain strength at high temperatures.
- Gamma prime phases in these alloys resist dislocation movement, making them incredibly strong but also brittle.
- Engineers balance gamma and gamma prime phases to optimize strength and ductility.
🧵 Single-Crystal Turbine Blades
- Single-crystal blades eliminate grain boundaries, the weak points in traditional metals, drastically improving resistance to creep and thermal fatigue.
- These blades are grown using a precise casting process involving a helical mold to ensure only one crystal survives.
- The result is a blade that can withstand extreme conditions for tens of thousands of flight hours.
🌡️ Cooling and Coatings: The Final Defense
- Internal cooling channels and film cooling holes circulate air to reduce blade temperatures.
- Ceramic coatings provide an additional thermal barrier, keeping the metal beneath up to 170°C cooler.
- Engineers are developing new coatings to resist molten dust, further extending blade life.
AI-generated content may not be accurate or complete and should not be relied upon as a sole source of truth.
📋 Video Description
How does a jet engine not melt? Sponsored by KiwiCo - Use code VERITASIUM to get 50% off your first monthly KiwiCo Crate! https://www.kiwico.com/VERITASIUM
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0:00 How a jet engine works
3:18 Why are jet engines so big?
5:17 The Inside of a Jet Engine
8:49 Edge Dislocation
11:11 The First Jet Engine
12:48 Inside the Rolls-Royce Precision Casting Facility
17:07 Nickel Superalloys - Gamma Prime
23:58 Crystal Structure
25:38 Making a Turbine Blade
32:22 Why don’t turbine blades melt?
35:30 Throwing Sand Into a Jet Engine
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A big thanks to Ben Todd, James Banks, Ben Fifoot, Doug Smith, Stefan Wagner, Rumaanah Hoosen and the rest of the team at Rolls-Royce.
A huge thanks also to Professor Howard Stone and Dr George Wise from the University of Cambridge.
We’re also incredibly grateful to Professor Jaafar A. El-Awady, Dr Karen A Thole, Professor Cathie Rae, Professor Paul Withey, Professor Pedro Patrício, Professor José Tavares and Ryan Moreman for their time and expertise.
Thanks to Institute for Materials, Ruhr University Bochum, SFB Transregio 103 for the animation showing the microstructure of the nickel superalloy. Full youtube video here - https://www.youtube.com/watch?v=wYHch5QIWTQ
Thanks to Professor Hongbiao Dong for the animation showing the grain selection in a single crystal turbine blade. Full youtube video here: https://www.youtube.com/watch?v=br9iaeYYxSM
References: https://ve42.co/JetEngineRefs
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Writers - Emilia Gyles, Casper Mebius & Derek Muller
Producer & Director - Emilia Gyles
Presenters - Derek Muller & Henry Van Dyck
Editor - Trenton Oliver
Camera Operators - Jack Coathupe, Justin Wood, Emilia Gyles, Henry Van Dyck & Derek Muller
Animators - Mike Radjabov, Emma Wright & Fabio Albertelli
Additional Editors - James Stuart & Peter Nelson
Researcher - Aakash Singh Bagga
Thumbnail Designers - Ren Hurley, Ben Powell & Abdallah Rabah
Production Team - Josh Pitt, Matthew Cavanagh, Anna Milkovic & Katy Southwood
Executive Producers - Casper Mebius & Derek Muller
Additional video/photos supplied by Getty Images, Storyblocks
Music from Epidemic Sound