Twin Turbo Cross Flow Combustor Design

Project Title

Twin Turbo Cross Flow Combustor Design

Project Area of Specialization Mechanical EngineeringProject Summary

Twin Turbocharged Cross Dual Tubular combustor (TTX2Tc), which has taken a deviating appearance in comparison to the classical axial small scale turbojet.  The TTX2Tc is based on two identical engine segments with a turbocharger unit, combustion chamber and propelling nozzle. A Propane fed fuel system that is capable to deliver a sufficient amount of fuel, an oil system that provide the bearing with lubricant to sustain the high rotational speed, a pressurized start system to accelerate the turbo shaft, a ignition system to start the combustion process and a experimental engine frame for tests and verifications. This analytic design is created to be a complete and functional jet engine after the manufacture and assembling. The concept and the innovative part of the TTX2Tc are that two turbochargers is used and that those are interconnected through the combustion chambers. Two combustion chambers ,  intake- and outlet nozzle are also used and  the rapport is structured in a way that the design of the combustion chamber, the choice of turbocharger and all the subsystems have individual chapters.

Project Objectives

Objectives:

 1) Design, simulate and construct a small-scale jet engine.

 2) Design and manufacture the combustion chamber and propelling exhaust nozzle.

Aim:

With satisfying characteristics, (SFC , Fnet , easy to manufacture, assemble , low costs)

Core Components:

• Turbocharger unit, Compressor çè Turbine

• Combustion chamber

• Propelling exhaust nozzle

Project Implementation Method

During the project time the engine design concept has changed from a hydrogen axial concept till a reversed flow turbocharged platform design; Twin Turbocharged Cross Dual Tubular combustor (TTX2Tc), which has taken a deviating appearance in comparison to the classical axial small scale turbojet. The TTX2Tc is based on two identical engine segments with a turbocharged unit, combustion chamber, and propelling nozzle. These two sets together create a crossed system for the fluid flow which gives some advantage of fewer parts to analyze.

For this configuration to work, five subsystems are designed from products available on the market that will serve the engine: A Propane fed fuel system that is capable to deliver a sufficient amount of fuel, an oil system that provides the bearing with lubricant to sustain the high rotational speed, a pressurized start system to accelerate the turboshaft, an ignition system to start the combustion process and an experimental engine frame for tests and verifications. This analytic design is created to be a complete and functional jet engine after the manufacture and assembling, but as the project had a limited amount of resources in form of finance and project members this phase is left for the next coming project team to fulfill. The current engine design also has the potential for performance improvement and further development such as an alternative fuel system for bio or hydrogen fuels, adaptation for a bypass ratio or an extra turbocharger stage, the addition of a regulation and control system, and other subsystem improvements.

The concept and the innovative part of the TTX2Tc are that two turbochargers are used and that those are interconnected through the combustion chambers. The engine apart from its subsystems consists of two turbochargers, two combustion chambers, and an intake- and outlet nozzle. The rapport is structured in a way that the design of the combustion chamber, the choice of the turbocharger and all the subsystems have individual chapters. For an illustration of the engine without its subsystems see the figure below

The TTX2Tc engine

The two main Parts of this engine are the Combustion chamber and Turbocharger unit.

Benefits of the Project

Research-based project on novel Twin Turbocharged Cross Dual Tubular combustor design ((TTX2Tc). The primary purpose of this project is to test the design and patent it along with making pathways for the commercialization of this design concept in hobbies aircraft. This design may later be used for military purposes after continual research and development. The path from concept idea to design, manufacturing and verification is a relatively complex and recourse demanding process, and therefore first we are focusing on the combustion chamber design and its cross arrangement which makes novelty in the project. 

Technical Details of Final Deliverable

Turbochargers are today widely used in broad spectra of application fields for different

implementations such industrial usage, electric power generation or internal combustion

engine improvements, but are presumably less used in aspect of jet engine purpose as it is a

immeasurable science of its own. Three configurations of a turbo charger unit are:

Figure 1: Axial Compressor with axial turbine

Centrifugal Compressors in Jet Engines

A Centrifugal Compressor is a type of dynamic compressor with a radial design. The rotating impeller in a centrifugal compressor takes in air which is pushed further away from the rotational axis by centrifugal force. This movement of air results in an increase in kinetic energy. The kinetic energy is then converted to pressure when the air is slowed down through a diffuser. The compressed air is then sprayed with fuel and an electric spark lights the mixture. The burning gases expand and blast out through the nozzle. As these gases blast out backward, thrust is produced pushing the aircraft forward. The hot air which goes to the nozzle drives a turbine which in turn drives the impeller.

Efficiency

The Centrifugal compressor is a single-stage unit with a pressure ratio of 4:1. A single-stage unit of the axial compressor gives a pressure ratio lesser than that of the centrifugal compressor. However, the axial compressor’s pressure ratio can be increased by adding more stages or units. This would however increase the overall size and weight of the compressor and hence the engine. Therefore, for small dimensions and use in smaller aircraft, it can be concluded that the centrifugal compressor is more efficient than the axial compressor. The efficiency of the centrifugal compressor itself can be further increased by altering its dimensions. Mathematical modeling has shown that an optimal centrifugal compressor has an impeller exit radius of 56.5mm [1], an impeller exit blade angle of -36.8 degrees, and a diffuser inlet blade angle of 77.1 degrees. These dimensions would result in the centrifugal compressor having higher efficiency, a higher pressure ratio, and lower work input, which are the ideal conditions for an optimal compressor.

In this project we have had to fabricate and design a combustion chamber. Many aspects were taken into consideration when fabricating the chamber which include combustor types, diffuser, dome section, swirler, fuel nozzle, annulus, primary zone and dilution zone. These can be seen in Figure 4

Figure 4: Overview of Combustion Chamber

Final Deliverable of the Project Hardware SystemCore Industry Energy Other Industries Manufacturing Core Technology OthersOther Technologies Clean TechSustainable Development Goals Affordable and Clean EnergyRequired Resources

Item Name	Type	No. of Units	Per Unit Cost (in Rs)	Total (in Rs)
			Total in (Rs)	72300
Turbo Chargers	Equipment	2	16500	33000
OIL PUMP	Equipment	1	4000	4000
TEMPERATURE GAUGE	Equipment	1	4200	4200
SS 304 3mm Sheet length 250mm x 3	Equipment	1	4500	4500
SS 304 3mm sheet length 400mm x 2	Equipment	1	6600	6600
SS 316 sheet	Equipment	1	3000	3000
Pressure Gauge	Equipment	1	5000	5000
DC MOTOR	Equipment	1	2000	2000
Miscellaneous	Miscellaneous	1	10000	10000