Pulsejet Final-1.docx

A PROJECT REPORT ON

“PULSEJET ENGINE” Submitted in partial fulfillment of the requirements of the award of the degree of BACHELOR OF TECHNOLOGY AEROSPACE ENGINEERING

Simranjit Kaur (GU-2015-0168) Rajesh Kumar (GU-2015-0166) Amit K. Chauhan (GU-2015-0150) UNDER THE GUIDANCE OF Mr. Assistant Professor Department of Aerospace Engineering Faulty of Engineering , Design and Automation GNA University Shri Hargobindgarh, Phagwara

2018

ACKNOWLEDGMENT I am highly grateful to the Faculty of Engineering, Design and Automation

of

GNAUNIVERSITY,

SHRI

HARGOBINDGARH,

PHAGWARA(PB.)for providing this opportunity to carry the final project in six months on Pulse-jet . I would like to express my gratitude to other faculty members of our stream Mr.Prabhjeet Singh and Mr. Harikrishna Chavhan for providing academic inputs, guidance & encouragement throughout in the completion of this project. I would like to express a deep sense of gratitude and thank to Incharge of our Faculty Mr. Vikrant Sharma, without whose permission, wise counsel and able guidance, it would have not been possible to complete the project in this manner. The help rendered by MR. HARIKRISHNA CHAVHAN, Supervisor for experimentation is greatly acknowledged. Finally, I express my indebtedness to all who have directly or indirectly contributed to the successful completion of my half industrial training.

Signature of the Student

Abstract

The objective of this research is to understand the Thrust force parameters and thermodynamic characteristics of conventional pulse jet engine. The geometrical parameters and performance aspects of the engine were studied including different different models like simple valve less, with turbulator and with C-D nozzle. Calculations were made on geometrical parameters for a design of a pulse jet engine in ANSYS (Fluent). In this research we made three catia V5 Models of pulse jet engine and then done the analysis with different different flow properties and thermodynamic properties.

CONTENTS Chapter \ No. List \of Figures \\]List of Abbreviations \];,

1

\];\Introduction to Pulsejet Engine 1.1History 1.2How does a valveless engine work 1.3 Advantage 1.4 Disadvantage 1.5 Limitations

2

Design of Pulsejet engine 2.1 Operation Equation 2.2 Valve Flow Area 2.3 Exhaust Pipe Length 2.4 Tube Shape 2.5 Thrust (Output) 2.6 Materials Used 2.6.1 Application 2.6.2 Properties 2.7 Starting Procedure

3

Conclusion

4

Reference

14

=+

CHAPTER 1 INTRODUCTION TO PULSEJET ENGINE 1.1 History The pulsejet is one of the simplest propulsion devices requiring no turbo-machinery, or moving parts in some cases. The pulsejet was originally conceived in the early 1900s and developed into a successful propulsion system by the Germans in WWII for the V-1 ‘buzz bomb’. Their simple structure and light weight make them an ideal thrust-generation device, but their thermodynamic efficiency is low compared to gas turbine engines due to the lack of mechanical compression, which results in low peak pressure. Due to this low efficiency, the pulsejet received little attention after the late 1950s. However, pulsejets with no moving parts may be advantageous for building smaller propulsion devices. The thermodynamic efficiency of conventional engine (such as gas turbines and both SI and CI engine), decreases non-linearly with decreasing characteristic engine length scale. Also, small scale engines with moving parts are more prone to breakdown due to fatigue of the moving components. Pulsejets, especially valveless pulsejets, are attractive as candidates for miniaturization due to their extremely simple design.

Why do we need pulsejet engines? We have operational jet engines, big andsmall and they run longer and more efficient that any pulsejet engine. That’strue, but you can’t build a lightweight jet engine that’s deliver 3-10 kg thrusteasily. But with a pulsejet, you can.So what do we use them for? Small engines are mainly used to give thrust tomodel aircrafts. 1.2

How Does Valveless Pulsejet Work?

When the fuel-air mixture combusts in the chamber, the process generates a great amount of hot gas very quickly. This happens so fast that it resembles an explosion. The immediate, explosive rise in internal pressure first compresses the gas inside and then pushes it forcefully out of the chamber. Two powerful spurts of hot expanding gas are created – a big one that blows through the tailpipe and a smaller

one blowing through the intake. Leaving the engine, the two jets exert a pulse of thrust – they push

Fig 1.1 Simple balloon the engine in the opposite direction. As the gas expands and the combustion chamber empties, the pressure inside the engine drops. Due to inertia of the moving gas, this drop continues for some time even after the pressure falls back to atmospheric. The expansion stops only when the momentum of the gas pulse is completely spent. At that point, there is a partial vacuum inside the engine. The process now reverses itself. The outside (atmospheric) pressure is now higher than the pressure inside the engine and fresh air starts rushing into the ends of the two ports. At the intake side, it quickly passes through the short tube, enters the chamber and mixes with fuel. The tailpipe, however, is rather longer, so that the incoming air does not even get as far as the chamber before the engine is refilled and the pressure peaks. One of the prime reasons for the extra length of the tailpipe is to retain enough of the hot exhaust gas within the engine at the moment the suction starts. This gas is greatly rarified by the expansion, but the outside pressure will push it back and increase its density again. Back in the chamber, this remnant of previous combustion mixes vigorously with the fresh fuel/air mixture that enters from the other side. The heat of the chamber and the free radicals in the retained gas will cause ignition and the process will repeat itself. The spark plug shown on the picture is needed only at start-up. Once the engine fires, the retained hot gas provides self-ignition and the spark plug becomes unnecessary. Indeed, if spark ignition is left on, it can interfere with the normal functioning of the engine.

You may wonder about the sharp transition from the intake tract into the chamber. It is necessary to generate strong turbulence in the incoming air, so that it mixes with injected fuel properly. A gentler,

Fig no.: 1.2 U-shaped Valveless pulsejet

1.3 Advantages of Pulse Jet Engine: A key advantage of the pulsejet engine, to which no othermechanical thrust device compares, lies in its simplicity. Though thephysical fundamentals of operation may be far from simple, thepulsejet's construction especially that of the valve less design, isexquisitely unsophisticated. This fact alone places the pulsejet as aforerunner in the innovative field of miniature propulsion. Pulsejetshave begun to receive renewed interest as a possible source ofminiature and/or micro propulsion. However, a basis for poweredthrust should not be considered its only application. The valve lesspulse jet could be an excellent source for micro-heating. Pastinvestments have been made toward the use of conventional-sizedpulsejets in central heating systems. Cost is significantly reduced bythe simplistic nature of valve less pulsejet construction.

The pulsejet engine has a peculiar property of pulsatingcombustion, it can be self-compressing. In the pulsejet, the fuel-airmixture does not burn steadily, at a constant pressure, as it does in theother jet engines. It burns intermittently, in a quick succession ofexplosive pulses. In each pulse, the gaseous products of

combustionare generated too fast to escape from the combustor at once. Thisraises the pressure inside the combustor steeply, which increasescombustion efficiency. The pulse jet is the only jet engine combustor that shows a netpressure gain between the intake and the exhaust. All the others haveto have their highest pressure created at the intake end of the chamber.From that station on, the pressure falls off. Such a decreasing pressure serves to prevent the hot gas generated in the combustor from forcing its way out through the intake. This way, the gas moves only towards the exhaust nozzle in which pressure is converted to speed. The great intake pressure is usually provided by some kind of compressor, which is a complex and expensive bit of machinery and consumes a great amount of power. Much of the energy generated in the turbojet engine goes to drive a compressor and only the remainder provides thrust. The pulsejet is different; the exhaust pressure is higher than the intake pressure. There is pressure gain across the combustor, rather than loss. Moreover, the pulsejet does it without wasting the power generated by combustion. This is very important. About 5% gain in combustion pressure achieved by this method which improves overall efficiency.

1.4 DISADVANTAGES OF VALVELESS PULSEJET: 

A big problem is that the gain in efficiency offered by pulsating combustion is not at all easy to utilize for propulsion.



Unsteadiness generates loss.



Pulsations are dangerous for the brittle axial turbine blades.



For the same engine bulk, you get less thrust than with the competing jet engines.



The pulsations produce horrible noise and mad vibration.

1.5 Limitations of Pulse jet Engine: A big problem is that the gain in efficiency offered by pulsating combustion is not at all easy to utilize for propulsion. Paradoxically, the central problem here is the same

as the Source of the benefit namely, pulsation. The very means of increasing combustion efficiency makes it difficult to take advantage of the result. The real potential for the pulsejet has always been in its use as the combustor for a turbine engine, rather than as an engine in itself. Its ability to generate pressure gain is greatly multiplied in a high pressure. environment. Compared to the more usual constant-pressure combustor, it can either give the same power with much smaller mechanical loss and lower fuel consumption, or much greater power for the same amount of fuel. Unfortunately, a turbine demands steady flows to function efficiently. Unsteadiness generates loss. Also, pulsations are dangerous for the brittle axial turbine blades. Radial turbines are tougher in that respect, but they are less efficient, especially so with intermittent flow. They are mostly used to exploit waste heat, as in a turbocharger, rather than as prime movers. Researchers have toyed with converting pulsations into a steady flow, but most methods proved inefficient.

1.6 Kadenacy Effect: In the explanation of the working cycle, the inertia drives the expanding gas out until the pressure in the chamber falls some way below atmospheric. The opposite thing happens in the next part of the cycle, when the outside air pushes its way in to fill the vacuum. The combined momentum of the gases rushing in through the two opposed ports causes the chamber briefly to be pressurized slightly above atmospheric. There is thus an oscillation of pressure in the engine caused by inertia. The pressure swings from way above atmospheric to partial vacuum and back again, in damped oscillation . This is called the Kadenacy Effect.

1.7 Objectives of this Project: Pulse jet engines have recently been recognized as promising propulsion technology that offers advantage in thermodynamic cycle efficiency, hardware, simplicity and operation scalability. The potential for self-aspiration operation is highly attractive for the perspective of efficiency and operation.

CHAPTER 2 The Design of Pulsejet Engine Thanks to Don Laird who made a drawing according to a factory-built example in 1993 and Kenneth Moller, who published the plans on his website at the end of the 1990s, a Chinese manufactured engine has become a popular design among amateur engine builders.

Fig 2.1 Pulsejet Plan Though legend says that it was designed in Europe, there is little evidence to support the story. In the 1950s and early 60s, it was produced by CS of Shanghai, until very recently a notable manufacturer of conventional 2-stroke piston engines for model aircraft. The company no longer exists – or at least does not manufacture model engines anymore. Two models were available on the US market – the SJP-1 (22” long, rated at 2.6 lbs static thrust) and SJP-2 (34” long, rated at 5.1 lbs static thrust). Both were designed to use liquid fuel (regular car gasoline). Today, most run on propane, but that is a later, amateur development. The engine is back in production, after a fashion. You can order stainless steel parts from Conception GLC Inc., a Canadian company run by pulsejet enthusiasts and involved in several interesting engine designs. The picture above shows the engine put together from their parts kit.

Fig 2.2 Pulsejet Engine

It is a very interesting and very controversial engine. Unlike the Logan, the intake port (which also serves as the auxiliary exhaust) branches out from the chamber very close to the exhaust proper. Instead of fresh mixture entering the chamber on one side and hot gas on the other, they enter virtually from the same side, in streams that impinge on each other at an angle of approximately 45 degrees. Some designers have been quite taken by the layout, sometimes to extremes. The mid1960s effort of a Frenchman, Rene Malroux, on the next picture is a case in point. I have no data on its performance, but it would have to be extraordinary to justify the forbidding bulk. On a more reasonable level, Larry Cottrill of Iowa, a tireless inventor of practical designs accessible to the amateur, has developed his Focused wave Engine (FWE) as a slightly simpler to build and entirely vice less kind of ‘Chinese’. The picture shows an example built by Eric Beck roaring away on the snowy background. One of its notable features is a very short length by valveless pulsejet standards – just 26 in. Opinions on the effectiveness of the Chinese engine vary. Some builders have found it a waste of time. One builder I know, who built his example after a few successful Lockwood engines, described the output of his ‘Chinese’ as “a hamster blowing through a straw”. It has to be noted, however, that his version had a straight, constant section tailpipe and did not have flared lips either on the intake or the tailpipe ends. Both details would tend to reduce performance.

Fig 2.3 Pulsejet in Action

Other people say the Chinese produces an adequate amount of thrust for its size and mass. One expert even claims it is one of the best designs around. It is possible that the poor-performing engines were built to wrong proportions, however. That would account for the unusual discrepancy among the performance accounts.

2.2 Material selection and properties There are many different kinds of metals out of which the metals with there melting points is obtained, these selection of the material should be based on according to the required result & accuracy for which it to be designed and cost or the value also fetch a vital role. in general, mild steel is opted for the construction of pulse jet engines .due to ease weld & wide verities & ability Mild steel are also termed as carbon steel which is having a high melting point of 1410 deg C (2570 deg F).However, medium carbon steel, high carbon steel have the melting temperature that ranges from 1425-1540 deg C (2600-2800 deg F). The low carbon mixtures say (0.05-0.15%) in mild steel do not have a more effect on the melting point of cast iron, which is 1538 centigrade. considering as well as Looking at the Iron-Carbon phase diagram which shows that the decreased from this melting temperature will be only a few some of the degrees. At higher mixtures of carbon (2-4%), as in casst iron, the melting temperature is gradually reduced. This alloy starts melting at 1154 centigrade, and is completely liquid metal at this level by 1200-1400 centigrade which depends on carbon content mixtures, Then the melting temperature of steel depends on the type of steel which are chosen in designing. Carbon steel has a melting point of 1425 degrees C to 1540 degrees C which is quite high than the usual steelthe use of the electric arc welding as for stitching before the TIG welding in the welding-section. The current was around 140. Depending on type of metal and thickness of material.. First the easy parts were joined in order to get an over view of the engine .and later tolerance parts were joined .

From Drafting , Designing, Construction , Testing Drafting and Designing As an old saying engineers construct the world .you live with what you design. So the drafting

process of our was with the held of auto cad software .which is a worlds widely used drafting software. used by the designers and engineers of present day .so we have made a 2d model & 3d too. And have used various tools of auto cad such as material selection, rendering, realistic, lights ground shadows & volume, area calculator in order to make our design near to a pratical model . first the subject is drawn in 2-D and then it is made to 3-D . computation increases as you go deep into the meshing in auto cad to make surface texture better . 3-D MODEL OF A VALVE LESS PULSE JET ENGINE

2.3 Construction and Fabrication Next step to move was with the construction of prototype. So, we have selected the material for prototype as jess iron with gauge 18 which was easy to work with then we rolled the sheet according to our geometry. then we moved with the part of soldering and assembling of all the parts. & finally it was put to test. With positive results of its working as desired.

A prototype of a valve less pulse jet engine at an initial level. Advanatages and Disadvantages of the Pulse Jet Engines construction

Extreme simplicity

Extreme efficient combustion & very less fuel is used

Low cost of Medium to

largest engines can bur almost any flammable material. However it possess some of the drawbacks as

Its noise level is very high

It has high radiant heat levels

Smallest engines only successful with extremely fast burning fuels

The engine

thrust can be increased byredesigning the nozzle section, also different composite materials could be tried to construct the engine which would reduce the weight to the thrust ratio.

PJ15 pulsejet engines have been designed and constructed in order to provide Power and reliability, Light weight, Ease of assembly and maintenance, a choice of fuel systems, extended reed valve life, throttle able (injected version only). These engines are the result of a comprehensive development program that has produced a number of innovative new designs.These simple, effective, light-weight engines can be put to many different uses including Powering model airplanes, boats, cars, etc.Basically an enhanced Schmidt tube design, these engines have an enlarged combustion zone, straight tailpipe and divergent tail cone.

We worked on CATIA V5 to design the product. As per the requirement we had worked on three different products by undertaking many variables as a input like temperature and pressure.

2.4

Case 1: Simple Valveless Pulse-Jet Engine.

Procedure: 1. Mark a circle of diameter 68mm on X-Y plane and pad it with length of 550mm . 2. Take a another circle of 2 mm diameter on Y-Z plane and pad it 4mm. 3. Our product is ready. Save it. 4. Then go to Ansys workbench. Import the geometry there.

5. Start

doing

meshing

over

that.

6. After that go to simulation part. In Models, there take the pre-mixed combustion , and viscous as standard k-epsilon. 7. In materials, take methane and oxygen along with air ,fluid and solid. 8. In boundary conditions , change the inlet and methane-inlet from velocity inlet to pressure inlet. Put the values in Gauge total pressure as 101325 Pa and supersonic/initial gauge pressure as 600000 Pa in both . 9. Then, take the reference values from methane and take the temperature as 900K. 10. In solution initialization, just consider the Standard Initialization and compute it from methane-inlet. 11. Last step is run calculation .Give iterations of 1000 and compute it.

12. Next to plot the graphs and find the thrust and mass flow rate in that.

Fig 2.4 Simple pulsejet- catia v5 multi- view

Fig 2.5

Meshing for simple valveless pulsejet.

Fig 2.6 Simple Valveless pulsejet- Pressure Contours

Fig 2.7 Simple Valveless pulsejet- Velocity Front view Vectors

Fig 2.8 Simple Valveless pulsejet- Velocity back view Vectors

Inlet Temperature

Inlet Pressure

Thrust

Mass flow rate

900

101325

12.321256

1.7292981

1200

101325

12.319366

1.7292481

1400

120000

15.019373

1.8851146

1600

150000

19.210823

2.107596

1800

200000

26.078553

2.4358069

Table 2.1 Variation of Thrust and Mass flow rate w.r.t inlet temperature and pressure

Graphs representation Fig 2.9 1. Mass flow rate Vs. Thrust Thrust

Mass flow rate

30 26.078553 25 19.210823

20 15.019373 15

12.319366

12.321256

10 5

1.7292981

1.7292481

2.107596

1.8851146

2.4358069

0 1

2

3

4

5

Fig 2.9 2.Mass flow rate Vs. Temperature mass flow rate

Temperature

2000

1800

1800

1600

1600

1400

1400

1200

1200 900

1000 800

600 400 200

1.7292981

1.7292481

1.8851146

2.107596

2.4358069

0 1

2

3

4

5

Fig 2.10

3.Mass flow rate Vs. Pressure Pressure

Mass flow rate

250000 200000 200000 150000 150000 120000 101325

101325

100000

50000 1.7292981

1.7292481

1.8851146

2.107596

2.4358069

0 1

2

3

4

5

Fig 2.11 4. Pressure Vs.Thrust Pressure

Thrust

250000 200000 200000 150000 150000

120000 101325

101325

100000 50000 12.321256

12.319366

15.019373

19.210823

26.078553

0 1

2

3

4

Case 2: Convergent-Divergent Pulsejet-Engine  Procedure: 1. Our product is ready. Save it. 2. Then go to Ansys workbench. Import the geometry there. 3. Start doing meshing over that. 4. After that go to simulation part. In Models, there take the pre-mixed combustion , and viscous as standard k-epsilon.

5

5. In materials, take methane and oxygen along with air ,fluid and solid. 6. In boundary conditions , change the inlet and methane-inlet from velocity inlet to pressure inlet. Put the values in Gauge total pressure as 101325 Pa and supersonic/initial gauge pressure as 600000 Pa in both . 7. Then, take the reference values from methane and take the temperature as 900K. 8. In solution initialization, just consider the Standard Initialization and compute it from methane-inlet. 9. Last step is run calculation .Give iterations of 1000 and compute it. 10. Next to plot the graphs and find the thrust and mass flow rate in that.

Fig 2.12

C-D Nozzle Pulse-jet Engine

 Ansys Results:

Fig 2.13

1: Static Pressure Contours

Fig 2.14

2: Velocity Contours

 Variation of Inlet temperature ,pressure w.r.t thrust and mass flow rate Mass Flow

Inlet Temperature

Inlet Pressure

Thrust

900

101325

100.3936

1.045947435

1200

101325

100.3936

1.145947435

1400

120000

118.60755

1.50054692

1600

150000

149.38187

1.50561259

1800

200000

202.3493

1.664151463

Graphs representing Fig 2.15

1. Mass flow rate Vs. Thrust

Rate

Thrust

Mass Flow Rate

250

202.3493 200 149.38187 150

118.60755 100.3936

100.3936

100 50 1.045947435

1.50054692

1.145947435

1.50561259

1.664151463

0 1

Fig 2.16

2

3

5

2.Mass flow rate Vs. Temperature

Temperature 2000 1800 1600 1400 1200 1000 800 600 400 200 0

4

Mass Flow Rate 1800 1600

1400 1200 900

1.045947435 1

Fig 2.17

1.145947435 2

1.50054692

1.50561259

3

4

1.664151463 5

3.Mass flow rate Vs. Pressure

Mass Flow Rate

Pressure

250000 200000 200000 150000

150000 100000 101325

101325

120000

50000 1.045947435

1.145947435

1.50054692

1.50561259

1.664151463

0 1

Fig 2.18

2

4.Pressure Vs.Thrust

3

4

5

Pressure

Thrust

250000 200000 200000 150000 150000 101325

101325

120000

100000 50000 12.321256

12.319366

15.019373

19.210823

26.078553

0 1

2

3

4

5

Case 3: Pulse-jet with Turbulator  Procedure: 1. Mark a circle of diameter 68mm on X-Y plane and pad it with length of 554mm . 2. Take a another circle of 2 mm diameter on Y-Z plane and pad it 4mm. 3. To create a helix . Make a dot at a distance of 33mm and then gave a command of helix from wireframe module. 4. Then gave rib command of pitch 10mm and height 550mm. 5. Our product is ready. Save it. 6. Then go to Ansys workbench. Import the geometry there. 7. Start doing meshing over that. 8. After that go to simulation part. In Models, there take the pre-mixed combustion , and viscous as standard k-epsilon. 9. In materials, take methane and oxygen along with air ,fluid and solid. 10. In boundary conditions , change the inlet and methane-inlet from velocity inlet to pressure inlet. Put the values in Gauge total pressure as 101325 Pa and supersonic/initial gauge pressure as 600000 Pa in both . 11. Then, take the reference values from methane and take the temperature as 900K. 12. In solution initialization, just consider the Standard Initialization and compute it from methane-inlet.

13. Last step is run calculation .Give iterations of 1000 and compute it. 14. Next to plot the graphs and find the thrust and mass flow rate in that.

Pulse-jet engine with turbulator

Isometric view of pulse-jet with turbulator

 Variation of Inlet temperature ,pressure w.r.t thrust and mass flow rate

Mass flow Rate

Temperature

Pressure

Thrust

1.8264054

900

101325

15.048067

1.8263526

1200

101325

15.049287

1.9848062

1400

120000

18.189215

2.2210342

1600

150000

23.272193

2.3583135

1800

200000

26.25341

1.Mass flow rate Vs. Thrust Mass flow Rate

Thrust

30 26.25341 23.272193

25 20

18.189215 15.048067

15.049287

15 10 5

1.8264054

1.8263526

1.9848062

2.2210342

2.3583135

0 1

2

3

4

5

2. Mass flow rate Vs. Temperature Mass flow Rate

Temperature

2000

1600 1400

1800 1600 1400 1200

1800

1200 900

1000 800 600 400 200

1.8264054

1.8263526

1.9848062

2.2210342

2.3583135

0 1

2

3

4

5

3. Mass flow rate Vs. Pressure Mass flow Rate

Pressure

250000 200000 200000 150000 150000 101325

120000

101325

100000 50000 1.8264054

1.8263526

1.9848062

2.2210342

2.3583135

0 1

2

3

4

5

4.Pressure Vs.Thrust

Pressure

Thrust

250000 200000 200000 150000

150000

120000 101325

101325

100000 50000 15.048067

15.049287

18.189215

23.272193

26.25341

0 1

2

3

4

5

Drafting details of pulsejet with tabulator

Conclusion After analyzing all the results with different catia models we find that the net thrust force is maximum in the C-D nozzle model and the mass flow rate is very low which is more efficient than the other two models simple valve less and with the turbulator. Also by changing the flow parameters we find various amazing results of flow properties of pulsejet.

REFERENCES