INSTITUTE OF AVIATION10 N GREEN MONOPROPELLANT THRUSTER

Samantha Booth

Jordan Kenton

Patrick Nienhaus

Erich Zahn

• The number and frequency of past and future space missions

• Variation in satellite sizes and the availability of rocket engines for them

• Green fuels and current market fuels

MARKET ANALYSIS

HYDROGEN PEROXIDE

• Decomposes into steam and oxygen gas• spontaneous decomposition at high temperatures

or with catalyst• high exhaust temperatures, low molecular weights• safe

• Dpecific impulse increases with concentration• High density, non-toxic, non-corrosive, non-reactive• Easy to handle, inexpensive• Release response for HTP is to rinse with water• Lower specific impulse, higher density specific impulse• Storable?

• lowest storage hazard class

MONOPROPELLANT COMPARISON

• HTP has one of the largest densities.• Exemplifies the ideal green monopropellant

• only questionable area is the storability

• HTP is the recommended monopropellant.

CEA RESULTS

• Using tables from various websites, a list of materials and their compatibility with HTP was made.

• Eliminating all materials that did not

meet an excellent rating left these

materials.

• This is list was used to start finding

materials that could be used in

constructing the engine.

POTENTIAL MATERIALS

CLOSER LOOK AT MATERIALS

Steel 316 Inconel 625

Strength Strong Very Strong

Thermal Average High

Machining Easily formed Tough

Cost ~$4/Kg ~$15/Kg

Inconel 625 Material

Properties

Steel 316 Material

Properties

VALVES

• Many different applications:• Submarines

• Oil Piping

• Missiles

• Robots

• There are many different kinds of valves:• Poppet

• Spool

• Proportional

• Ball

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VALVE CHARACTERISTICS

• Thruster Valves• Before the Decomposition

Chamber

• Dual Redundant

• Continuous Duty• Doesn’t Overheat

• Current Drain• Amount Used

• Cv Factor • Units of Gal/Min• Given Temperature and Pressure

• Correction Factor• Multiple Flows• Manual Shutoff?

SOLENOID VALVE

• Controlled by a Solenoid

• Normally Closed/Open

• AC vs. DC

• Different types of solenoid valves

• Proportional

• Poppet

• Spool

POPPET VALVE

• Component covers internal passage blocking flow.

• They are self cleaning, simple, and can be normally closed.

www.europeanoilandgas.co.uk

VALVE

VENTURI NOZZLE

• Venturi nozzle was required to control the mass flow.• Research showed that an inlet angle of 30⁰ and an outlet angle of 20⁰ was appropriate.• Length was dependent on an inlet diameter of 3.9688 mm and an outlet diameter of 9 mm and the specified angles.• Will be connected to the valve at the inlet section and the decomposition chamber at the outlet section.

FACEPLATE DESIGN

• Distribute propellant evenly across the catalyst bed

• Since it’s a monopropellant no atomization is required

• Combustion chambers need atomization

• Shower head design

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SHOWER HEAD

SHOWER HEAD ANALYSIS (DISPLACEMENT)

SHOWER HEAD ANALYSIS (STRESS)

DESIGN PARAMETERS OF CATALYST BED

• Required diameter and length to obtain optimal decomposition of HTP (~95%)

• Obtained diameter of approximately 9 mm

DESIGN PARAMETERS OF CATALYST BED

• Length of approximately 30 mm was obtained through interpolation of the best fit line.

THERMAL AND STRUCTURAL ANALYSIS

• Using Bartz equation, an approximate heat load was found.

• The convection constraint is based on the properties of air.

• The temperature constraint is based on the properties of the decomposition of HTP.

• This was then applied to the test section to analyze the result.

THERMAL AND STRUCTURAL ANALYSIS

NOZZLE PARAMETERS

• The two most important nozzle parameters: Throat Area, Area Ratio (Exit to Throat)

• These can be found using the following relationships:

NOZZLE PARAMETERS

• CF is a property of the geometry.

• C* is a property of the propellant, H2O2.

Pc 8 Bar

Gamma 1.28 (constant)

c* 1015 m/s

c* efficiency 0.9 5

P∞ 1 Bar

Isp 130 s

ṁ 0.0078 kg/s (for 10N Thrust)

At 9.46 µm2 (1.74 mm radius)

0 10 20 30 40 50 60 70 800

2

4

6

8

10

12

14

16

18

20

Pressure Ratio Pc/Pe

Thru

st

(N)

Thrust vs Pressure Ratio for Different AR at Ambient 1 Bar

AR:1.5

AR:2

AR:3

AR:4

AR:10

NOZZLE PARAMETERS

• Choosing the Area Ratio

• For example, if ideal expansion is desired:

Chamber Pressure (bar)

Pressure RatioArea Ratio for Ideal

Expansion

6 6 1.563

8 8 1.843

10 10 2.108

NOZZLE CONTOUR

• Simple, 15o divergent half angle

• Easier to design/manufacture

• On large thruster, is inefficient, energy losses, non uniform exit flow

• For our purposes, for such a small thruster, this method is appropriate to save time, effort, and cost.

• Uses MoC to minimize length, therefore minimizing weight

• High initial divergent angle, levels off to a small exit divergent angle

• More efficient, less energy loss, uniform exit flow

• Harder to design/manufacture

Converging SectionDue to the low mach, low energy flow, the convergent section is simple. A convergent half angle of anywhere from 20o to 60o will work.

Conical Diverging Section Optimum Bell Diverging Section

NOZZLE CONTOUR

A 60% bell nozzle has a length that is 60% of a 15o conical nozzle.

CURRENT NOZZLE DESIGN

Covergent Half-Angle 50o

Divergent Half-Angle 12o

Throat Area 7.57 µm2 (1.55 mm Radius)

Exit Area 15.9 µm2 (2.25 mm Radius)

Area Ratio 2.11

FULL DESIGN

THANK YOU

QUESTIONS?