Hypersonic Travel A Game-Changing Technology

Dora E. Musielak, Ph.D.

University of Texas at Arlington - UTA Aerospace Professional Speaker Series 28 September 2016

Contact Author: dmusielak@uta.edu

Hypersonic Transport

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 2

SST Mach 2.2 HST Mach 7

Hypersonic Missiles

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 3

60 miles per minute

Rapid response to time-critical targets. JP-fueled engine would enable a medium-size rapid response ISR vehicle with operationally- relevant range capability. Hypersonic missile offers advantage of flexible recall and en route re-direction. Global fast-reaction reconnaissance missions.

Lockheed HSSW

X-51A

Hypersonic Air-Breathing Flight: Highlights

• Hypersonic Air-Breathing Propulsion (HAP) Technology

– Dual-Mode Scramjet

• DARPA/USAF Military Programs

– From X-51A to HAWC and SR-72

• NASA Reusable SLV Concept: TSTO TBCC

• Europe: Skylon and HST

• Critical Technologies and Needed Breakthroughs

– Research Topics

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 4

Aerothermodynamics-Propulsion

Aerothermodynamic performance cannot be decoupled from propulsion performance due to shared surfaces and flow field interactions.

11/17/2016 5 High-Speed Air-Breathing Propulsion

Dora Musielak

Forebody Shaping, Shock Structure and Boundary-Layer State Impact Engine Mass Capture and Combustor Performance

Variable Geometry Dual-Mode Scramjet Operation

Exhaust Plume and Nozzle Expansion Impact Vehicle Pitching Moments and TPS

Exhaust Plume Interaction with Airframe, Control Surfaces

Mach 7 CFD Model Image: NASA

Scramjet Propulsion 5 < M < 15

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 6

Combustion

0

External

Compression

1

Internal

Compression

(Isolator)

3 4 8 9

Internal

Expansion External

Expansion

Expansion Compression

0 3 Adiabatic Compression

30 TT

3 4 Isobaric heat addition

43 TT

4 9 Adiabatic Expansion

94 TT

Freestream condition

Capture

area A0

0M 9AFuel injection

Air-breathing Engine No Turbo-compressor To produce static thrust, scramjet requires ram compression, i.e., forward flight speed

)( 090 VVmF

Air-Breathing Propulsion Challenge

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 7

Scramjet engine has a much more challenging task than rockets. Consider flight at an optimum dynamic pressure:

2

2

00

Vq

Mass flow ingested by inlet

0

000000

2

V

AqVAm

Inlet capture area A0 varies slightly with Mach number and angle of attack. As cruise velocity increases , mass flow decreases reducing thrust .

This is why scramjet engine has to occupy a large fraction of vehicle’s cross-section area.

Mach 10 vehicle needs ~ 80% of its frontal area to capture air (subsonic airliner needs only 25%, and Mach 3 airplane uses about 40%).

)( 090 VVmF

Air-breathing Propulsion Performance

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 8

X-51

X-43A

f

ABsp

mg

FI

0

Specific Impulse

)s(spI

090 VVmFAB

Scramjet Critical Elements of Feasibility

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 9

Compression and expansion processes are very critical to overall propulsion system performance. We estimate velocity ratios implied by Isp

fg

VVMa

fg

VVV

fmg

FI sp

0

0900

0

090

00

1/1/

For M0 > 5 scramjets operate ~ stoichiometrically. With H2 fuel f = 0.0293

sp

spI

MMa

gI

V

V

000

0

0

9 00096.00293.01

0V9V

0M

10

9 V

V

Fractional velocity change across engine is very small as M0 > 6. A small inefficiency in nozzle or inlet could have large consequences for overall scramjet engine performance. Efficient Inlets and nozzles are essential for scramjet propulsion

Compression Expansion

090 VVmF

Fuel Energy

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 10

Fuel is characterized by its energy content per unit mass. Heat of reaction hPR represents (ideal) fuel energy density, i.e., fuel thermal energy per unit mass of fuel.

Fuel hPR (BTU/lbm) hPR (kJ/kg)

Hydrogen, H2 51,571 119,954

Methane, CH4 21,502 50,010

Ethane, C2H6 20,416 47,484

Octane, C8H18 19,256 44,786

JP-4 18,400 42,798

JP-7 18,702 43,500 Rate at which chemical reactions make energy available to engine cycle is

PRf hmrateenergy Chemical

Overall efficiency of HAP cycle:

PRf hm

FV

0

0rateenergy Chemical

PowerThrust

Due to volume limitations, entirety of available hPR cannot be realized. Burner efficiency represents it

iPR

aPR

bh

h

,

,

Heat addition in burner:

PRbin hfhhq 34

)(HkJ/kg1014.1 2

5 inq

7)-(JPkJ/kg1013.4 4 inq

Fuel/Air Ratio, f

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 11

Fuel/air ratio, indicator of combustion conditions 0m

mf

f

General chemical equation for HCF + air indicates all carbon, hydrogen and oxygen atoms are consumed in chemical reaction, yielding as products carbon dioxide and water:

22222421

79

221

79

4N

yxOH

yxCONO

yxHC yx

yx

yx

m

mf

f

st

4103

336

0

For hydrogen fuel, x = 0 and y = 2, stoichiometric fuel/air ratio 0291.0stf

Ideal upper limit of fuel/air ratio is known as stoichiometric fuel/air ratio. It represents condition where complete combustion of oxygen and fuel takes place.

For JP-7 fuel, x = 12.5 and y = 26, stoichiometric fuel/air ratio 06745.0stf

Specific Impulse of Hypersonic Propulsion

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 12

111

2/1

00

0

0

t

inKEsp

h

qf

gf

VI

Overall propulsion kinetic energy efficiency

KEnozzlerKEcombustoKEinletKE 0

Heat added per unit mass fuel PRbin hfq

Curran, et al., 1991

Kinetic energy efficiency must be determined accounting for real gas effects and nonequilibrium chemical reaction effects, very important in both combustors and nozzles.

KEOK

Stoichiometric combustion

PRbin hfhhq 34

)(HkJ/kg1014.1 2

5 inq

7)-(JPkJ/kg1013.4 4 inq8 M

Engine-Vehicle Integration

• Proper aerodynamic integration of propulsion system with vehicle is required for efficient hypersonic flight. This includes integration of vehicle structures, material, thermal management, controls, and subsystems.

• To capture required airflow, it is necessary to use entire forebody underneath vehicle as compression surface, shaping it for high efficiency.

• Entire afterbody underneath vehicle must be used as a free expansion surface.

• Entire vehicle underside must be carefully designed to satisfy engine performance under all flight conditions. Bottom of vehicle becomes an integral part of propulsion system.

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 13

Shock Shock

Compression

Engine

Forebody/Inlet Afterbody/Exhaust

X-30 National Aerospace Plane (NASP) Studies 1987 - 1995

X-43A Hypersonic Experimental Vehicle

16 Nov. 2004, it reached a cruise speed of Mach 9.6 on H2 fuel. Total flight time: 12 seconds

X-51A Waverider

On May 1, 2013, it reached a cruise speed of Mach 5.1 on HC fuel. Total flight time: 210 seconds

Heritage HAP Technology

11/17/2016 14 High-Speed Air-Breathing Propulsion

Dora Musielak

HRE Program 1964 - 1974

Testing and Studies: Australia HyShot Russia CIAM •GASL projectile …….. .. more

NASA X-43A M10 Vehicle

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 15

Goal: Demonstrate, validate and advance technology for hypersonic aircraft powered by an airframe-integrated scramjet engine.

Flight History -Flight 1: Mach 7 Target, June 2, 2001 Booster Failure -Flight 2: Mach 6.91, March 27, 2004 Fully Successful -Flight 3: Mach 9.68, Nov. 16, 2004 Fully Successful

First Flight of scramjet powered vehicle. ─ Demonstrated H2 burn, attained high flight Mach number, non-symmetrical stage separation (required for TSTO)

WEIGHT: 3,000 lbs / 1400 kg Image: NASA

NASA X-43A Project

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 16

Mach 9.65 Flight Nov 2004

Three-flight Project (scaled Mach 10 cruiser) 2 at Mach 7, power-on test 11 seconds* 1 at Mach 10

Air launched on a highly modified Pegasus booster 7 year project (1996 – 2004) ~ $230 M investment Second flight demonstrated scramjets can ignite at Mach 6.83, fly at 94,000 ft (28.7 km) altitude. Third flight maximum Mach 9.68, ~ 7 seconds

Image: NASA

X-51 WaveRider Mach 5

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 17

Cruiser Length: 168 in ( 4.26 m), Max. Width: 23 in ( 0.58 m)

Stack Length: 301 in ( 7.6 m)

Pratt & Whitney Rocketdyne Scramjet SJY61, Ethylene and JP-7 Fuel

X-51A WaveRider Flight Test

18

X-51A scramjet-powered waverider made hypersonic history on 26 May 2010. Vehicle soared at Mach 5 for over 3 minutes, setting a new hypersonic world record.

Stack Length: 26 ft (7.6 m) Empty weight: 4,000 lb (1,814 kg) Scramjet: P&W Rocketdyne SJY61 Fuel: JP-7 (270 lbm) Maximum speed: Mach 7+

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak

Scramjet can produce 400 to 1000 lb of thrust, capable of accelerating more than 6437 km/h (4000 mph)

X-51A Scramjet Engine Demonstrator

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 19

Flight History 1st Flight – 26 May 2010: 143-second burn to Mach 5. Perfect flight would have lasted 100-sec more and accelerated cruiser to Mach 6. Thermal seal breach at nozzle interface caused hot gases to leak. 2nd Flight – 13 June 2011: Booster to Mach 5. Scramjet lit, failed to transition to full power 3rd Flight – 14 August 2012: Fin Failure 4th Flight – 1 May 2013: 210-second combustion to Mach 5.1 and Parameter ID Maneuvers (Glide)

Scramjet Inlet Design

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 20

Critical Aerothermodynamics

Viscous

Interaction

Aerodynamic

Heating

Shock Wave /

Boundary Layer

Viscous Interaction

(SWBLI) Inlet Unstart

Inlet Spillage/BL

Ingestion

Bow Shock/Cowl

Shock Interaction

Jet

Interaction

Entropy Layer

Swallowing

11/17/2016 21 High-Speed Air-Breathing Propulsion

Dora Musielak

Hypersonic Aerodynamic environment is extremely harsh and hypersonic vehicles function near edge of system capability.

Boundary Layer Transition

X-43A Coping with Aerodynamic Heating

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 22

At M < 7, horizontal tail leading edges 2600°F (1400 °C) and nose 2000°F (1090 C°) At Mach 10, Tw ~ 3600°F (1900°C)

Leading edge protection

Second X-43A vehicle, being mounted under right wing of B-52B launch aircraft. Source: NASA DFRC Photo.

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 23

Source: McClinton, 2006

Maximum working Temperatures Titanium alloys: 1600R (890 K) Superalloys: 1800R (1000 K) Metal matrix composites: 4500R Coated C-C composites: 5400R (3000 K)

Adiabatic wall temperatures in hypersonic flight can reach 5,000-15,000R (2778-8333 K)

TPS Cooling Requirements

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 24

For thermal protection system we need to know whether existing fuel flow rate is sufficient to satisfy total cooling requirements.

Total rate at which fuel can remove thermal energy

hfc is amount of thermal energy that can be absorbed by unit mass of fuel.

Assuming that most heat is due to turbulent flow, total rate at which heat must be removed from engine surfaces (required cooling)

Ratio of available fuel cooling to required fuel cooling:

For a balanced system

Physical heat absorption capacities of hydrocarbon aerospace fuels crucial for cooling

fcff hmQ

0

5/1

0

5/11

005/1

0

2

000

A

A

q

VmA

V

VVAqQ w

wwwr

w

fc

r

f

A

A

V

q

K

hf

Q

Q0

5/11

0

5/1

0

0

5/1

0

5/11

0

A

A

q

VKhf w

fc

Fuel Cooling Properties

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 25

Physical heat absorbed by standard aerospace fuels in going from tank conditions to 1000 K (1800 °R). In all cases, fuel is stored in liquid state and heated to vapor state before injecting into engine flowpath as a gas.

Hydrogen is best engine coolant for hypersonic vehicles. Costs and logistic complexities of cryogenic hydrogen, as well as exceedingly low density force us to consider conventional hydrocarbon fuels such as JP-7 for lower hypersonic flight regime. JP-7 has better heat absorption than JP-8, and produces more of gaseous products that reduce ignition times.

Fuel Liquid Density

lbm/ft3 (kg/m3)

fst Physical heat

absorption hfc

BTU/lbm (kJ/kg)

fsthfc

BTU/lbm (kJ/kg)

Hydrogen, H2 4.74 (75.9) 0.0291 6500 (15,100) 189 (440)

Methane, CH4 18.7 (300) 0.0583 1460 (3400) 85.1 (198)

JP-7, C12.5H26 49.5 (793) 0.0675 860 (2000) 58.0 (135)

Current HAP Military Programs

11/17/2016 High-Speed Air-Breathing Propulsion –

Dora Musielak 26

DARPA/USAF Hypersonic Air-breathing Weapon Concept (HAWC) flight demonstration of critical technologies for effective and affordable air-launched hypersonic cruise missiles, hydrocarbon scramjet-powered propulsion to enable sustained hypersonic cruise. Lockheed SR-72, unmanned, TBCC Mach 6 aircraft intended for intelligence, surveillance and reconnaissance envisioned to succeed SR-71 Blackbird.

USAF/Lockheed Martin’s High Speed Strike Weapon (HSSW) hypersonic missile. Image Credit: Lockheed Martin Co.

SR-72 twin-engine TBCC aircraft designed for a Mach 6 cruise. Image Credit: Lockheed Martin Co.

Spaceplanes: Ground to Orbit

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 27

Chemical Propulsion

28

Air Breathing

(Brayton Cycle)

Rockets (Brayton Cycle)

Gas Turbine Engines No Rotor Engines

Turbo- fan

Turbo- jet

Pulse- jet

Ramjet and Scramjet

All Rockets

Turbofan + AB

Turbojet + AB

Hybrid or Combined Cycle Engine

Turbofan + Ramjet

Turbojet + Ramjet

Turbo-Rocket

Ram-Rocket

Rocket-Scramjet

Pre-Cooled Air Cycle Engine Synergetic Air-Breathing and

Rocket Engine (SABRE)

Rocket

ee VmF

)(0 oe VVmF

Scramjet

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak

75% of weight at lift off was propellant, and of this, 83% was oxidant (mLOX= 1.3 million lbm)

Combined Cycle Propulsion

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 29

• TBCC

• Turbine-Based Combined Cycle (TBCC) use turbine engines (TE) to boost the vehicle to takeover (TO) speed.

• TEs are mounted in separate ducts to facilitate cocooning to isolate them from high enthalpy flow of hypersonic speeds. TBCC uses high specific impulse (Isp) TE booster for subsonic operation.

• Substantial data from testing, analysis, and conceptual studies.

• RBCC

• Rocket-Based Combined Cycle (RBCC) Engines have a rocket as primary propulsion element to boost the vehicle to TO speed.

• Ejector rockets behave both as a rocket for producing static thrust, and also as a ramjet because inlet air is compressed and burned with fuel to produce thrust.

• Fully integrated with one single flowpath.

• Limited data but substantial predictions based on conceptual studies.

NASA Two-Stage to Orbit (TSTO) TBCC

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 30

Booster: TBCC propulsion

Orbiter: all-rocket propulsion

0 < M < 3 Turbine w/rocket boost for takeoff 3 < M < 8 Dual-Mode Scramjet 8 < M < 10 for pull-up maneuver to staging point (orbiter release) cruise-back initially scramjet-powered with final portion as glider to terminal landing. NASA Image

NASA Baseline TSTO Mission Profile

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 31

Unmanned, fully reusable and sized to deploy (or retrieve) a 20,000 lb payload to a 100100 nmi., 28.5° inclination orbit.

Ref: Snyder, Robinson, and Ferlemann, (2010)

TBCC Issues

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 32

Issues: Dual integrated inlet operability and performance issues: unstart, inlet flow distortion effects, bleed requirement/control, and operability margins Propulsion mode transition: high-temperature turbine dual-mode scramjet Wide operating range variable geometry controls Integration/Interaction issues: Inlet/engine compatibility/unstart, etc.

SKYLON: SSTO Spaceplane

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 33

Cylindrical payload bay: L = 13 m (42 ft 8 in) D = 4.8 m (15 ft 9 in)

Body: carbon-fiber-reinforced polymer space frame Multiple layers of reflective foil thermal insulation

L = 82 m (269 ft), D = 6.3 m (21 ft)

LH2: 220 tonnes

GTOW = 275 tonnes

Source: REL Ltd.

Skylon Ascent Trajectory

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 34

TO M ~ 0.5

M ~ 5.2

Karman line 100 km

Source: REL Ltd.

SABRE Rocket

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 35

s800,20

gm

FI

f

sp

Source: REL Ltd.

SABRE Rocket: Air Breathing Mode

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 36

0 < M < 5.5 0 < h < 26 km (16 mi)

Air must be compressed to ~140 atm before injection into combustion chamber This raises air temperature so high that it would melt material walls. SABRE avoids this by first cooling air to −150 °C (−238 °F), using a pre-cooler heat exchanger until air is almost a liquid. Then a conventional turbo compressor compresses air to required pressure.

Excess air is passed down a spill duct which has a burner to recover some of drag losses.

Source: REL Ltd.

Hybrid Air-breathing Rocket

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 37

A simple translating axisymmetric shock cone inlet slows air to subsonic speeds using two shock reflections. Some air passes through a precooler into central core, and remainder goes directly through a ring of bypass ramjets. Central core behind precooler uses a turbo-compressor run from same gaseous helium loop which compresses air and feeds it into four high-pressure rocket combustion chambers.

Why a Curved nacelle? To help provide lift proportional to center of mass.

Civil Hypersonic Transport

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 38

European Space Agency LAPCAT II: LAPCAT-A2 Mach 5 airliner powered by a pre-cooled air-turbo ramjet, and Mach 8 airplane powered by a ramjet engine, both fueled by LH2

JAPAN’s Exploration Space Agency: Hytex, Mach 5 hypersonic airliner propelled by a pre-cooled turbojet engine

At Mach 5, air Tt ~ 1320K impractical to compress air due to work requirement and because resulting compressor delivery temperature would be too high.

GTOM: 400 tonnes, Fuel mass: 198 tonnes (LH2)

Issues for Hypersonic Airplanes

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 39

Environment: Lifetime of water vapor decreases exponentially, taking from 30 years at 25 km altitude to less than one year above 32 to 34 km. M8 LAPCAT 2 airliner will fly above 33 km to minimize environmental impact.

Sonic Boom: generates 160-db noise that travels to ground and permanently damage human ears. Hypersonic planes to fly over North Pole and cross Bering Strait, avoiding populated land; it will fly higher so its ground shock waves will be spread out and produce a smaller shock wave

Aerodynamic Heating: Plane travelling at M5+ will withstand surface temperatures ~1,000°C. Advanced materials required.

Fuel Consumption: M8 plane consumes two times more LH2 per second than a M4 plane. M8 plane gets to destination in half time so fuel consumed overall is ~ same

Hypersonic Propulsion Challenges

• Operating efficiently and reliably over an extraordinarily large range of flight conditions, including, 0 < M < 6, 0 < M < 10, and from sea level to orbital altitude.

• Accomplishing stable, efficient mixing and combustion of fuel and air within burner of reasonable size.

• Provide structural integrity necessary for reusable system despite hostile environmental conditions.

• Integrate multiple cycle engines into a single propulsion system capable of operating in multiple modes, e.g., turbojet-ramjet-scramjet-rocket, or rocket-scramjet-rocket.

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 40

We are improving analytical tools, ground and flight testing facilities, and developing technologies

to finally prove that hypersonic air-breathing propulsion systems are ready for routine operations.

Hypersonic Technologies

Advanced High Temperature Materials - new formulations and processes for metals and composite materials

Fuels and Injection Techniques

Structures – lightweight primary structures, reusable tanks for cryogenics

Optimization of High Performance Scramjets

Computational Fluid Dynamic (CFD) Methods and Algorithms – computer simulation

Heat Control – Cooling techniques and insulation, regenerative fuels, etc.

Ground and Flight Tests under realistic flight conditions

11/17/2016 41 High-Speed Air-Breathing Propulsion

Dora Musielak

www.grc.nasa.gov/WWW/StructuresMaterials/AdvMet/research/titanium.html

Structures, Materials, and Thermal Management

• A scramjet-powered vehicle will take a more leveled ascent trajectory.

• Due to low T/W scramjet needs more time to accelerate. This depressed trajectory implies that vehicle stays a long time in atmosphere at hypersonic speeds, so atmospheric friction is a huge problem.

• Heat addition produced by combustion at high velocities and temperatures is another significant factor.

• Materials for structure must have excellent properties and be adequate to deal with these and other hypersonic flow phenomena.

• Cooling of the engine’s structure by fuel or radiation is essential.

11/17/2016 42 High-Speed Air-Breathing Propulsion

Dora Musielak

Glass, et al, 2002

At M < 7, X-43A’s horizontal tail leading edges 2600°F (1400 °C) and nose 2000°F (1090 C°) At Mach 10, Tw ~ 3600°F (1900°C)

U.S. Hypersonic Ground Test Facilities

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 43

Hypersonic Scaling Laws

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 44

What scaled propulsion components and initial conditions must be tested to provide adequate scaling parameters with respect to various performance parameters of interest in order to obtain a desired level of performance at a particular scale of the hypersonic engine?

Numerical Methods for Hypersonic Flows

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 45

With limited ability to adequately represent hypersonic flow experimentally, hypersonic CFD predictions becomes even more difficult because we lack substantial experimental data for a variety of flow geometries and flight conditions.

Large-Eddy Simulation (LES) of HIFiRE scramjet

Hypersonic flow dynamics is complicated by interaction of boundary layer and shear layer with shock waves, leading to flow separation and instability not amenable to simple analysis. CFD aims to perform direct numerical simulation (DNS) for all aerodynamic flows of interest. High-speed reacting turbulent flows are challenging to simulate fully. Large eddy simulation (LES) allows for modeling of small scales of turbulence while resolving large-scale turbulent structures; currently limited to low Reynolds number flows.

HAP Technologies and R&D Topics

• Dual-Mode Combustors

• Materials and Structures light-weight, high-T, high-strength O2 compatible, CC

• CFD Modeling, Simulation, and Prediction

• Ground Testing diagnostics, scale, time

• Flight Testing infrastructure, telemetry

• Thermal Management TPS

• High-Energy Density Propellants

• TBCC Mach 4+ Turbine Acceleration

• Fuel Injection and Flameholding

• Design Optimization Methodology

• Hypersonic Aerothermodynamics

• Propulsion Flowpath Development

• Actuation Mechanism, Hot Valves, Seals

• TBCC Turbine/Scramjet Mode Transition

• TBCC Inlet Optimization

• RBCC Mode Transition Control

• Scaling Laws

• Combined and/or Hybrid Propulsion Cycles Dual-Mode Scramjet, Turbine/Scramjet/Rocket

• Design Optimization

• Boundary Layer Transition

• Combined Cycle Propulsion Mode Transition

• Airframe-Propulsion Integration Aerothermodynamic Performance

• Inlet Unstart Prediction/Control

• Combustor Flameout

• Shock Interaction Control

• Ignition/Flameout/Flameholding Testing, Modeling and Simulation

• Combustion Stability

• Combustor/Isolator Interaction

• RBCC and TBCC Mode Transition

• RBCC Inlet/Nozzle Integration

• TBCC and RBCC Flow Path Optimization

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 46

11/17/2016 High-Speed Air-Breathing Propulsion

Dora Musielak 47

The Race for Hypersonic Travel Has Begun …