Project Pulse-Jet
Group 4
Jeffrey Dennen
Justin Marriott
Brian Melo
Matthew Skillin
What is Project Pulse–Jet?
▫ Project Pulse – Jet
 is an analytical study of how a pulse-jet engine works.
▫ Our Goals
 To design, build and test a pulse-jet engine.
▫ Plan of Action
 Research and design a prototype of a pulse-jet engine.
 Build the prototype based on our design.
 Test the prototype against the theoretical analysis.
History of the pulsejet
• The pulsejet engine was first invented in the early 1900 by a Swedish inventor
Martin Wiberg
• Paul Schmidt, who engineered the first production pulsejet during the Second
World War with his flying bomb, the Argus V1.
▫ Nicknamed the “buzz” bomb because of the low hum it admitted during flight.
▫ Used by the Germans to bomb London from 1944-1945
▫ Over 9,000 V-1 were fired on England during WW2
• The pulsejet took a backseat in the engineering world when the turbofan jet
engine was invented
• Has returned to the engineering scene as
of late because of the interest in
Pulse Detonation Engines (PDE).
How does it work?
• A pulsejet engine is a very simple jet engine consisting of very little
to no moving parts. The combustion cycle comprises five or six
phases: Induction, Compression, (in some engines) Fuel Injection,
Ignition, Combustion, and Exhaust.
• The rapidly expanding gasses exit out of the engine and as this
happens a vacuum is created in the combustion chamber which
pulls in a fresh new air charge fro m the atmosphere, and then the
whole cycle repeats itself.
Combustion Cycle
Types of Pulse Jets
• There are two basic types of pulsejets.
▫ valve or traditional pulsejet
▫ valve-less pulsejet.
• The Argus V1 Schmidt was a valve pulsejet
• Most of the development work for the valve-less engines are done by
two American engineers Lockwood and Hiller.
• Types of Valves
▫ Petal
▫ High Efficiency Petal
▫ Valve Grid
Design Research
• The Lenoir cycle is an idealized
thermodynamic cycle often used to model
a pulse-jet engine.
• Comprises of 3 cycles:
▫ Heat added at constant volume.
▫ Adiabatic Expansion.
▫ Exhaust of the hot gasses at a
constant pressure.
• Thrust can be directly calibrated on the
basis that
the cycle is completed over two working
strokes.
Design Research
• C.E. Tharratt
▫ Discovered a surprising result that the ratio of duct
volume to effective length had a linear relationship to
the maximum static thrust or:
 V/L = 0.00316F
▫ This relationship has been compared to all known
pulse-jets from the large V-1 “flying bomb” of over 500
lb. thrust to the miniature Dyna-jets of 4-5 lbs. thrust.
 Thrust = 2.2 x Cross-Sectional area or F = 2.2A
Sample Calculations
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Pulse-Jet Body Design
Pulse-Jet Body Exploded
Taper
Combustion
Chamber
Exhaust Pipe
Valveless
Petal Valve
Valve Grid
Design Matrix for valves
• Ranked on a 1 to 10 scale (1 being the worst and 10
being
theEFFICIENCY
best) MACHINABILITY FUNCTIONALITY WEIGHT AESTETICS TOTALS
COST
Valve-less
10
5
10
10
10
4
39
Petal Valve
5
6
8
6
6
9
40
High
Efficiency
Petal Valve
5
8
6
8
6
9
42
Valve grid
2
10
4
4
4
7
31
Valve Design
• Sample Calculation.
▫ Valve area = (0.23 x mean cross-sectional area) /
0.6 assuming the valves are going to be
60% efficient.
▫ Valve Area = (0.23 x 7.72)/0.6 = 2.96 in
Valve Design
Valve Component Explode
Valve Body
Diffuser
Reed Valve
Final Design
Final Design Exploded
Valve Assembly
Body Assembly
Building and Testing
• Materials
▫ Pulse-Jets Main body.
 Rolled and seem welded using 0.063” Stainless Steel
Sheet Metal.
 Stainless Selected because of its higher resistance to heat
then mild steel.
▫ Valve Body
 CNC machined (Mill and Lathe) from 6061
Aluminum.
 Aluminum used for its light weight and its machinability.
▫ Reed Valve
 0.006” Spring Steel.
 low alloy, medium carbon steel or high carbon steel with
a very high yield strength. This allows objects made
of spring steel to return to their original shape despite
significant bending or twisting.
Combustion Chamber Drawing
Benchman Verification
Fuel and Fuel Delivery
• Fuel
▫ Propane
 Easily obtained.
 Boiling Point below room temperature.
 Being a gas allows for easier starting.
• Fuel Delivery System
▫
▫
▫
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Propane Tank
Propane lines
Gas Fitting Nozzle
Needle Valve
Testing
• Prototype will be tested to verify thrust output.
• Test Stand will be constructed to secure PulseJet safely.
• Digital scale will be attached to frame to
calculate thrust
Budget
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Stainless steel sheet metal, with labor: $150
Valve Body: $0 on hand
Reed Valves with machining labor: $25
Propane Tank: $0, on hand
Fuel Delivery System: $0 on hand
Instrumentation: $0 on hand
Test stand material: $0 on hand
Fuel: $50
Total: $175
Project’s Future
• Continue testing on prototype to gain further
knowledge of its operating cycle.
• Construct larger Jet using the knowledge
gained from this smaller prototype.
• Use larger engine to power to propel a
manned vehicle.
Thank You
• Group 4 would like to thank
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Professor Roberts
Professor Rourke
Mechanology Inc. (Attleboro, MA)
Wayne’s Sheet Metal
Paul’s Custom Exhaust
Project’s Lab Staff
Machine Shop Staff
Bibliography
• Simpson Bruce “The Enthusiasts'
Guide to Pulsejet Engines”
• http://www.aardvark.co.nz/pjet/
• http://www.zachmiers.com/pulsejetbo
ok/
• http://www.pulse-jets.com/
• Roy, Gabriel “Combustion processes in
propulsion control, noise, and pulse
detonation”
Questions?