International Journal of Advanced Science and Engineering Research www.ijaser.in Volume: 3, Issue: 1, 2018 ISSN: 2455-9288

EXPERIMENTAL INVESTIGATION OF COMPOUND PULSE-JET

T.Mythili1, P.Sivakumar2,M.Saravana kumar3, M. Sabaree4 1.Asst Prof, Department of Aeronautical Engineering, Mahendra Engineering College,Namakkal India 2.Asst Prof, Department of Aeronautical Engineering, Mahendra Engineering College,Namakkal India 3.Student, Department of Aeronautical Engineering, Mahendra Engineering College,Namakkal India 4.Student, Department of Aeronautical Engineering, Mahendra Engineering College,Namakkal India

Abstract The jet are either fuel consuming or have shortage of power. Thus we have created a new type of engine with a better design and less of drawbacks. The resultant is a hybrid of the engine and engine. The chamber of turbojet is replaced by pulsejet engine. The pulse jet used in a or thermojet. Since the and high pressure compressor blades are replaced with much simple pulsejet, thus the overall weight of the engine is reduced. The air entering the engine is divided into two parts, one passes along inner surface area of the turbojet casing and other part goes through the pulsejet for the combustion. The air passing though inner surface area acts as cooling medium for the pulsejet and will contribute for the thrust as it will increase the total mass flow rate at the downstream end of the engine. Mechanical efficiency of the engine will be increased as the moving mechanical parts will be decreased. Augmentor will be added later on for the pulse jet to increase the overall efficiency of the engine. If required a variant with can also be inducted. Keywords— pulsejet, thermojet, turbojet, turbojet, mass flow rate. 1. INTRODUCTION Among most of the jet engines many are fuel hungry engines and with soaring rise in fuel prices the operation of aerospace industry is getting costlier day by day. According to studies conducted by aerospace industries each and every ounce of weight reduction will result in increase in fuel economy. And some of the main drawbacks of a jet engine is that the maintenance is a very tedious job for commercial air liners as well as for the maintenance of military purpose jet engines The usual overhauling for the used in commercial airliners are in a range from 10000 – 30000 flying hours. Thus overhauling of a jet engine is very time consuming as well as resource consuming. Next with the increasing rate of accidents caused due to bird hits as well as foreign objects entering the jet engines usually in turbofan engines. These are the main drawbacks that we have kept in mind while developing this engine. 1.1.Basics Thus for the development of our hybrid engine these are the few basic but efficient type of engines of their kind, so for the knowledge of all we have provided aa overview of the basic engines that we have taken into consideration and conducted an extensive study about the given , different types of jet engines

1.1.1 Pulsejet Engine A pulse jet is defined as an engine in which pulse combustion happens. This engine is made of few or no moving parts. Its is in lightweight form having poor & gives

Copyright © 2018 by the Authors. This is an open access article distributed under the Creative Commons Attribution License, which permits 1040 unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. International Journal of Advanced Science and Engineering Research www.ijaser.in Volume: 3, Issue: 1, 2018 ISSN: 2455-9288 a low . The notable research on this engine includes the impulse engine which has repeated denotations in it, which gives high compression and good efficiency.

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Fig-1 Working of valved pulse jet

1.1.2 Valveless Pulse Jet Valveless pulsejet engines consist of no moving parts. The exhaust flow comes out of the engine is controlled by using its geometry. These release exhaust out of both the and the exhaust, but it tries to expel the exhaust go out of the longer tail pipe for more efficient propulsion. The principle is as same as the valved pulsejets, but it is based on engine’s geometry. Fuel is given as a gas or as an atomized liquid spray. The fuel is passed by either mixing it with the air in the or directly injected into the combustion chamber.. The intake valve is used to intake the air & gets mixed it with the fuel to combust, which also controls the of exhaust gas like a valve & limiting the flow but not stopping it altogether. The expanding gas while burning the air-fuel mixture is forced out of the exhaust pipe of the engine. During the exhaust cycle of the engine it also expels gas. The intakes are facing backwards in many valveless engines so that the thrust created add to the overall thrust, rather than reducing it. The combustion of valveless pulsejet creates two pressure wave fronts, one travelling down the longer exhaust tube & one down the short intake tube. A resonating combustion process can be achieved by properly tuning the system. Some valveless engines are extremely high in fuel consumption, while other designs use less fuel than a valved pulsejet, and a properly designed system with advanced components and techniques can rival or exceed the fuel efficiency of small turbojet engines.

Copyright © 2018 by the Authors. This is an open access article distributed under the Creative Commons Attribution License, which permits 1041 unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. International Journal of Advanced Science and Engineering Research www.ijaser.in Volume: 3, Issue: 1, 2018 ISSN: 2455-9288

Fig-2 3D model of pulse jet

Fig-3 working diagram of a valveless pulsejet 1.2 TURBOJET ENGINE Air intake A tube, or an air intake, is needed in front of the compressor to help it in directing the incoming air smoothly into the moving compressor blades. Stationary vanes are used in front of the moving blades in older engines that helped to direct the air onto the blades. The intake is also shaped to minimize any flow losses when the compressor is accelerating the air through the intake at zero and low aircraft speeds, and to slow the flow down for the compressor when the aircraft is operating above Mach 1. The air flowing into a turbojet engine must always be subsonic, regardless of the speed of the aircraft itself. Compressor

Copyright © 2018 by the Authors. This is an open access article distributed under the Creative Commons Attribution License, which permits 1042 unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. International Journal of Advanced Science and Engineering Research www.ijaser.in Volume: 3, Issue: 1, 2018 ISSN: 2455-9288

The turbine drives the compressor which rotates at a high speed, adding energy to the airflow and it squeezes it into a smaller space. The pressure and temperature of the air is increased by compressing it. When the compressor is smaller, the turns are faster. is extracted from the compressor section at various stages in most of the turbojet , to perform a variety of jobs including air conditioning pressurization, engine inlet anti- icing and turbine cooling. The efficiency of the engine is decreased by bleeding off the air, but the usefulness of the compressed air outweighs the loss in efficiency. There are two types of compressors are used in , axial & centrifugal. The overall pressure ratio is as low as 5:1 in early days. The splitting the compressor into two separately rotating parts by improvements made in aerodynamics, incorporating variable blade angles for entry guide vanes and stators, which has overall pressure ratios of 15:1 or more. The overall pressure ratios are 33:1 or more in modern civil turbofan engines. The air enters the combustion chamber after the compressor.

Combustion chamber The process of burning in a is different from that in a engine. The burning gasses are confined to a small volume in piston engine & as the fuel burns, the pressure increases. The air-fuel mixture in a turbojet is burnt in the combustor and passed through to the turbine bu a continuous flowing process without pressure buildup. Instead there is a small pressure loss in the combustor. The fuel-air mixture can only burn in slow moving air so an area of reverse flow is maintained by the fuel nozzles for the approximately stoichiometric burning in the primary zone. The combustion process is completed by introducing the compressor air & reduces thee temperature of the combustion products to a level which the turbine can accept. The combustion uses less than 25% of the air, & to keep the turbine limits, the overall lean mixture is used. Turbine Hot gases leaving the combustor expand through the turbine. Typical materials for turbines include inconel and Nimonic. The turbine vanes and blades have internal cooling passages. Air from the compressor is passed through these to keep the metal temperature within limits. The turbine is largely an impulse turbine in the first stage which rotates because of the impact of the hot gas stream. The gas is accelerated by convergent ducts in later stages. The energy transmission into the shaft is performed through momentum exchange in the opposite way that of the compressor. The compressor is driven by the power developed through turbines, as well as accessories like fuel, oil, and the accessory gearbox drives the hydraulic pumps.

Copyright © 2018 by the Authors. This is an open access article distributed under the Creative Commons Attribution License, which permits 1043 unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. International Journal of Advanced Science and Engineering Research www.ijaser.in Volume: 3, Issue: 1, 2018 ISSN: 2455-9288

Fig-4 3D design of Nozzle A high velocity jet is produced by expanding the gases through the exhaust nozzle. The ducting narrows progresses to a throat in a convergent nozzle. The high nozzle pressure ratio on a turbojet is enough to choke the nozzle at higher thrust settings. If, however, a convergent-divergent de Laval nozzle is fitted, the divergent (increasing flow area) section allows the gases to reach supersonic velocity within the divergent section. Additional thrust is generated by the higher resulting exhaust velocity.

Fig-5 3D model of the outer shell Thrust augmentation Thrust was most commonly increased in turbojets with water/methanol injection or afterburning. Some engines used both at the same time.

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Fig – 6 Working diagram of turbojet engine Final compound jet engine The base of the compound pulse jet engine is valveless pulsejet engine or thermojet. The combustion chamber in surrounded by fins it is then surrounded by a turbojet casing to regulate air flow around the pulse jet. There is a shaft axially placed along which the propellers as well as the turbines are mounted. The beginning and ending of the turbojet shell are equipped with diffusers which in turn increase the mass flow rate inside the shell. The air entering the shell acts as a cooling medium for the fins as well as the pulsejet which in turn contributes to the mass flow rate of the engine. Since there is no use for the high pressure compressor and combustion chamber separately it can be removed from the setup thus it contributes to the weight reduction of the engine.

Fig – 7 3D design of bearing There is various cone shaped nose like structures some stationary and some in rotation, which divert the flow of air using their geometry. since the resultant engine resembles the assembly of a turbofan engine because it has bypass of air i.e. a portion of air is flowing across the shell of the engine contributing to cooling and increasing mass flow of air, the other segment of air enters the combustion chamber and aids combustion. Thus the added advantages of the turbojet and turbofan is achieved. There is a significant reduction in weight and cooling of engine is achieved without bleeding of the engine as in case engaged in turbojet engine. The pulsejet has an added advantage of fuel versatility as it has been run with fuel ranging from coal dust to ATF to . With mild changes is fuel delivery system the pulse jet can run on a variety of fuels.

Copyright © 2018 by the Authors. This is an open access article distributed under the Creative Commons Attribution License, which permits 1045 unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. International Journal of Advanced Science and Engineering Research www.ijaser.in Volume: 3, Issue: 1, 2018 ISSN: 2455-9288

Fig -8. 3D model of assembled pulsejet Fig – 9 (a),(b) Front view and Isometric view of final model

3. RESULT AND DISCUSSION OF SIMULATION ANALYSIS Our work and the results obtained so far are very encouraging and reinforce the conviction that our compound pulsejet engine is practical and potentially very contributive to new generation aerospace industries to the production of more revolutionary engines with higher efficiency and increased overall performance of engine in all aspects . It is hoped that they may be constructed used high-strength, low- weight materials for deployment in more developed nations and settings or with very low tech local materials and local skills in less developed countries. The discussion has to be done based on the Simulation Analysis using Fluent and CFX and Design had been done by using CREO.

Fig – 10 Experimental setup of valveless pulsejet 4. ADVANTAGES  There is significant reduction in weight.  Fuel efficiency of the engine is increased.  Maintenance efforts are reduced.  Duration between overhauling is increased.  Chance damage by foreign bodies is reduced  Bleeding for cooling is not necessary  Mechanical efficiency of the engine is increased

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 Overall cost of the engine is reduced.  Variety of fuel can be used. 5. CONCLUSION The design process in first stage, includes the research, brainstorming, engineering analysis, and turbine design selection which completes the fall term. This project’s initial research & analysis is provided for its sharing of complications; the valuable information is provided when the final design is completed. The test run of the pulsejet in independent form is being tested in-house facility. The fuel systems is being proposed. One is the use of gaseous fuel such as , LPG or propane. This saves the hassles of using a carburetor of fuel injection setup. But in case of mass production the operating cost is high. The other option is using carburetor or fuel injection with liquid fuel such as kerosene, etc. The turbine blades are currently in initial designing stage and are expected to be manufactured within 6 months. There are still some final design options that must be finalized, and these decisions will be made before turbine construction begins. In addition to prototype testing the component is tested for flow analysis using computed fluid dynamics about the behavior of air mainly around the main pulsejet fins. Load acting on the main shaft using finite element analysis. The temperature distribution and stress localization on the pulsejet body is done using ansys software. The bearing used is of 2 types on is at the compressor inlet side and other type is placed near the exhaust of the pulsejet. Preferred is roller bearing. For high temperature resistance the proposed bearing is silicon carbide (SiC) ceramic bearings. The load stress analysis on the bearings is apex priority thus it is done using ansys software. The shell is the outer body and main part of our jet engine and is compiled in accordance with nozzle calculation with assumption of fluid being an isentropic fluid. Similarly the fluid flow analysis using Fluent or CFX . Reference [1] André OLLIVIER, ―STRUCTURE SIMULATION AND BLADE DESIGN OF AN ‖ NECMA site of Villaroche 77550 Moissy-cramayel, France, pp. 2-8 [2] AERO0015-1 - MECHANICAL DESIGN OF TURBOMACHINERY - 5 ECTS - J.-C. GOLINVAL – University of Liege (Belgium). [3] Brun, R. J., Olsen, H. L. and Miller, C. D. End-Zone as a means of suppressing knock in a spark-ignition engine. Restricted Bulletin No. E4127. Aircraft Engine Research Laboratory, Cleveland, Ohio. 1944 [4] Busuttil, D. Further Improvements to the Water Injection in a S. I. Engine Setup, Bachelor of Engineering (Hons.) Dissertation, University of Malta. 2014 [5] Busuttil, D., Farrugia, M., Camillieri, G. Mechatronics for water injection in SI enge, Mechatronika (ME), 2014 16th International Conference on Mechatrnonics 3-5 December 2014, Brno, Czech Republic Pages 308 – 313. ISBN: 978-80-214-4817-9 DOI No.: 10.4271/1999- 01-0568. DOI No. 10.1109/MECHATRONIKA.2014.7018276 [6] Corporation, B. B., ―OPA277, OPA2277 and OPA4277 Operational Amplifiers Specification Sheet – Applications,‖ March 1999. [7] Camilleri, G. Setup for Experimental Investigation of Water Injection in a Spark Ignition Engine, Bachelor of Engineering (Hons.) Disseration, University of Malta, 2013. [8] Dabelstein, W., Reglitzky, A., Schütze, A. and Reders, K. Automotive Fuels, Ulmann’s Encyclopaedia of Industrial Chemistry, 2007

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