System Level Overview of the Hypergolic Gelled

Propellant Lab (GPL)

Purdue University

Maurice J. Zucrow Laboratories

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Dr. Timothée L. Pourpoint

Dr. Steve Heister

Dr. William Anderson

Dr. Robert Lucht

Dr. Steven Son

GPL Overview

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Oxidizer workstation

Fuel workstation

General use fume hood

Data acquisition system

Ventilation system

Workbenches

Test stand

LASER

• Dedicated laboratory space for NTO-based and hydrazine-based propellant studies

• Dedicated ventilation system (0.02" H2O P between laboratory and control room)

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2

3 4

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Capillary Rheometer

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Droplet Burning/Vaporization

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• Gelled MMH Droplet Combustion

• Objective:

• Improve fundamental understanding of the burning behavior of gelled

MMH droplets

• System Capabilities

• Variable chamber conditions

• Inert or oxidizing environment

• Max pressure: ~10 atm

• Max temperature: ~450 K

• Optical access from multiple angles

Droplet Burning/Vaporization

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1) MMH evaporates from the

droplet surface during

combustion

2) A semi-rigid shell of HPC is

formed

3) The HPC layer blocks diffusion

of the fuel vapor

4) A bubble of MMH vapor is

formed under the HPC layer

(Fig 1-3 )

5) The pressure of the bubble

ruptures the outer layer (Fig 4)

6) A jet of MMH vapor is expelled

from the ruptured area (Fig 4-6)

t = 0ms t = 32ms t = 34ms

t = 35ms t = 38ms t = 39ms

1) 2) 3)

6) 5) 4)

• Results:

Droplet is approximately 2 mm in diameter

MMH Droplet Combustion in a N2O4 Environment

Droplet Burning/Vaporization

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• Droplets of MMH with 3 wt.% HPC show

dependency between mass burning rate and

droplet surface area.

• Disturbances to the combustion process

caused by accumulation of the solid HPC

layer diminish during the combustion

process.

• Droplets with a liquid layer exhibit the

opposite behavior with increasing

disturbances as combustion progresses.

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0.5

1

1.5

0 0.2 0.4 0.6 0.8 1R

ed

uced

Vo

lum

e V

/Vi

Reduced Time t/tb

MMH with 3% HPC

MMH with 3%

Tetraglyme

R² = 0.9122

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4

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8

10

12

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2 4 6 8 10 12

Mass

bu

rn

ing

rate

m

g /

s

Di2 mm2

Droplet Burning/Vaporization

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• High Repetition Rate Laser Diagnostics

• Objective

• Obtain insight into dynamics of MMH droplet combustion, flame

structure and provide data needed for chemical kinetics modeling

• System Capabilities

• Variable chamber conditions

• Planar Laser Induced

Fluorescence (PLIF) imaging at

up to 5 kHz to observe short

duration combustion phenomena

• Tunable laser wavelength to

excite the OH radical

• High frequency 3-D imaging with

rotating mirror

Droplet Burning/Vaporization

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2mm

2mm

Pc = 103.4 kPa Pc = 413.7 kPa

Impingement point

2mm

• Results

• OH PLIF images of liquid MMH

droplets burning in air

• OH PLIF images of impinging jet

test of H2O2 – Tetraglyme/NaBH4

Droplet Burning/Vaporization

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• Hypergolic Droplet Contact Experiment

• Objective

• Explore fundamental combustion phenomena for contacting hypergolic

propellant droplets in a controlled environment

• System Capabilities

• Controlled environment

– Pressure

– Temperature

– Ambient gas composition and velocity

• Impact velocities

– Up to 10 m/s

• Optically accessible

– PLIF, thin filament pyrometry, absorption spectroscopy, etc.

Droplet Burning/Vaporization

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• Results

• Quantified pre-ignition explosion due

to rapid gas production with

MMH/RFNA

• Examined less toxic hypergolic

propellants

• DMAZ, TMEDA, TMEDA/DMAZ,

BMIMDCA, etc.

• Future Research

• Explore pre-ignition explosion at

higher impact velocities

• Shift toward less toxic hypergolic

propellants

MMH contacting RFNA

• Rheological Characterization of non-Newtonian Propellants

• Objective

• Investigate and quantify non-Newtonian fluid behavior at conditions

experienced by propellants during all stages of operation from low shear

storage up to high shear injection

Non-Newtonian Propellant Characterization

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• System Capabilities

• Low-intermediate shear rotational rheology

• Propellant yield stress, storage/loss

modulus, etc.

• High shear capillary rheology

• Safe testing of toxic propellants

• Controllable shear rate up to 106 1/s

• Remote operation at driving pressures

up to 3000 psia

Non-Newtonian Propellant Characterization

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Fuel Side of

Rheometer Cabinet Loading

Tube

Linear

Encoder

Piston

Rod

Waste

Collection Water Flush

Tank

Capillary Assembly

Capillary

Tube Pressure

Transducers

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Dashed lines represent viscosities

of liquid MMH and RP-1

Non-Newtonian Propellant Characterization

• Results are very similar for MMH and RP-1 gel

• Silica properties dominate rheological behavior

• Viscosity of the gel at high shear is much higher than that of the base fluid

• Direct impact on modeling efforts for gelled propellants

• Results

Spray Ignition/Combustion

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• Hypergolic Propellant Spray Ignition/Combustion

• Objective:

• Characterize and gain an understanding of the ignition and combustion

characteristics of hypergolic propellant sprays

• System Capabilities

• 60°Included Angle

• 360°Optically Accessible Chamber

• Variable chamber pressure and temperature

• Variable O/F, Rm, injection duration

• Highly repeatable injection conditions

• ~3 ms to steady state injection

• Pulsed operation

Spray Ignition/Combustion

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• Results:

• MMH/RFNA

• Less Toxic Hypergolic Propellants

• H2O2 – Triglyme/NaBH4

Pulse 1 Pulse 2 Pulsed Actuator Response

5 mm

5 mm 5 mm