A Very Short Introduction to Hypersonic Flight

Dr. Daning Huang

APUS Lab, apus.psu.edu

Aerospace multi-Physical and Unconventional Systems

Prepared for AERSP1, 09/16/2019

1

Outline

• What is hypersonics?

• How does (air-breathing) hypersonic flight work?

• What are the challenges?

• What’s next?

2© 2019 by Daning Huang

Mach number = Velocity / speed of sound

3Source: Computational Fluid Dynamics 2006

Supersonic:𝑀𝑎 > 1

Cylinder in hypersonic flow (M9.5) ©HyperFlowLab

Hypersonic: 𝑀𝑎 ≫ 1

Re > 105, 𝑀𝑎 ∼ 0.1

Subsonic:𝑀𝑎 < 1

© 2019 by Daning Huang

Hypersonic: Over five times speed of sound

𝑀𝑎𝑐ℎ 𝑁𝑜. =𝐹𝑟𝑒𝑒𝑠𝑡𝑟𝑒𝑎𝑚 𝑠𝑝𝑒𝑒𝑑

𝑆𝑝𝑒𝑒𝑑 𝑜𝑓 𝑠𝑜𝑢𝑛𝑑

4Source: NASA

© 2019 by Daning Huang

Airbreathing Hypersonic Flight

A scramjet (supersonic combustion ramjet) engine under testing

5© 2019 by Daning Huang

… for Rapid Global Access

Boeing Hypersonic Commercial Jet

6© 2019 by Daning Huang

… for Easier Access to Space

•More flexibleo Larger launch windowo All-weathero More basing options

•Cheapero Space shuttle: 10000$/lbo SpaceX: 2700$/lbo SSTO: <500$/lb

SSTO: Single-Stage-To-Orbit

7© 2019 by Daning Huang

The History of Hypersonics, Dr. R.P. Hallion

Historically speaking …

8Source: The Promise of Hypersonic Flight PhysicsWorld

Supersonic

Hypersonic

© 2019 by Daning Huang

So what are the differences?

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Source: NASA Hyper-X Project

© 2019 by Daning Huang

10

Source: The Promise of Hypersonic Flight PhysicsWorld

Source: Subsonic Aircraft Wikipedia

Subsonic jetsRelatively mature

Source: imgur.com

Supersonic jets• Different aerodynamics• Different design strategies• But manageable

Source: NASA Hyper-X Project

Hypersonic aircraft• Aerothermodynamics• Immature propulsion• Immature design

© 2019 by Daning Huang

Waverider: Make shockwave a friend

Source: ScienceDirect.net

Source: research.lifeboat.com

• Lift is generated by pressure differential

• Upper surface:• Expansion to near-vacuum• Limit of physics• 𝑝𝑢𝑝𝑝𝑒𝑟 ∼ 0

• Lower surface:• Compression using shock wave• 𝑝𝑙𝑜𝑤𝑒𝑟 ∼ 50𝑝∞

➢ High-lift configuration with low drag11© 2019 by Daning Huang

Scramjet: Light a match in Hurricane

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Engine size scaling

© 2019 by Daning Huang

Thermal Management: Song of ice and fire

Source: DARPA’s Materials Architectures and Characterization for Hypersonics (MACH) program

• Waverider generates high lift• But also external heat!

• Scramjet engine generates high thrust• But also internal heat!

➢ Thermal protection/management• ~2000 K• Material endurance• Structural robustness

13© 2019 by Daning Huang

The History of Hypersonics, Dr. R.P. Hallion14© 2019 by Daning Huang

•Maturing propulsion•Advanced materials•Supercomputers

Ups and downs in the past

15USAF SAB report “Why and Whither Hypersonic Research in the USAF”

Hypersonic Commercial Jet Image source: Boeing

SR-72Image source: Lockheed Martin

Res

earc

h e

ffo

rt

X-51 WaveriderImage source: Boeing

2020+

© 2019 by Daning Huang

Challenge: System-level Coupling – I

Structural dynamics

Aerothermodynamics

Thermoelasticity

Aeroelasticity

© 2019 by Daning Huang 16

Challenge: System-level Coupling – II

Aerothermoelasticity

© 2019 by Daning Huang 17

APUS Lab, apus.psu.edu

It’s happening!

• Missions and Vehicles• Operational Systems Aspects• Thermal Management Systems for Vehicles and all Subsystems• Propulsion Systems• Propulsion Components• Guidance and Control Systems• Materials and Structures for Vehicles and all Subsystems• Test and Evaluation• Computational Methods• Hypersonic Fundamentals and History

18© 2019 by Daning Huang

Opportunities for You

19Source: USAF SAB Report

• Background• Aging experts and workforce• Boosting hypersonic business

• Industry is looking for• Multi-disciplinary experts• Teamworkers• Quick learners

• I am also looking for young talents ☺• apus.psu.edu/join-us

© 2019 by Daning Huang

Thank you! Questions?