Project Pulse-Jet Group 4

Jeffrey DennenJustin Marriott

Brian MeloMatthew 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

Combustion Chamber

Taper

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 the best)COST EFFICIENCY

MACHINABILITY

FUNCTIONALITY

WEIGHT AESTETICS TOTALS

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▫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 Pulse-Jet safely.

•Digital scale will be attached to frame to calculate thrust

Budget •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

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/

pulsejetbook/•http://www.pulse-jets.com/•Roy, Gabriel “Combustion

processes in propulsion control, noise, and pulse detonation”

Questions?