Propulsion

Learning Outcomes

Subject Specific Intellectual and Research Skills

Having successfully completed this module you will be able to:

• Evaluate intuitively how, and explain why variations in the flight regime, design parameters and components performance affect the overall performance of a system.(P4,SM2b,SM3b)
• Calculate fundamental performance indicators of an entire engine (such as specific thrust and specific fuel consumption) for given flight regime, engine design parameters, and performance indicators of the engine components (such as the flight Mach number, compressor pressure ratio, and turbine efficiency etc.) (D1,D2,D3b,SM2b,SM3b)
• differentiate rocket engine cycle designs and relate this to performance requirements (EL2)

Transferable and Generic Skills

Having successfully completed this module you will be able to:

• Solve problems systematically (G1)
• Demonstrate study and time management skills (G2)
• Communicate work in written reports (G1,P3)
• Study and learn independently (G1,G2)

Subject Specific Practical Skills

Having successfully completed this module you will be able to:

• Appreciate some of the technical issues associated with aerospace propulsion design (SM1b)

Knowledge and Understanding

Having successfully completed this module, you will be able to demonstrate knowledge and understanding of:

• Propulsion system modules and the functional role of each subsystem in detail ((EA1b,EA2,EA3b,EA4b))
• The configuration of typical commercial engines and relation to their application (P1,P7,EL1,EL3,EL5)
• The architecture of launch vehicles and the role of various rocket motor stages ((EA1b,EA2,EA3b,EA4b))
• Typical propulsion system mechanical configurations and their performance indicators. (EA1b,EA2,EA3b,EA4b)

Fundamentals

• Breguet range equation, the standard atmosphere
• Steady-flow control volume analysis sufficient to introduce/define gross and net thrust, thermal efficiency, propulsive efficiency, overall efficiency and specific fuel consumption and specific impulse (in case of rockets)
• Two-property rule, Perfect vs. Semi-perfect gases, properties of mixtures of ideal gases
• First Law and Steady Flow Energy Equation. Definition of Stagnation Enthalpy
• Entropy and isentropic processes, compressible and incompressible flow, leading to stagnation properties. Definition of isentropic efficiency.
• 1D waves leading to speed of sound and Mach number.
• 1D gas dynamics leading to compressible flow relations, normal shock waves and nozzle flow

Ramjet

• Practical overview of technology and its application, distinction between RAM and SCRAM.
• Qualitative description of oblique shocks and 3D shock patterns in general and in the SR71 intake.
• Calculation of an ideal ramjet engine.

Combustion

• Mechanisms of combustion in propulsion systems (diffusion flames, flame propagation, autoignition, detonation waves); flame ignition and stabilisation.
• Combustion chemistry : chemical equations, air fuel ratio, equivalence ratio.
• Combustion thermodynamics: heat of reaction / calorific value, calculation of combustion temperature for given fuel input.
• Chemical equilibrium: calculate equilibrium composition for given temperature (consider reactions of NO, CO and also ones for H2/O2 rockets). Explain how dissociation results in lower effective heat release.

Rockets

• Specific impulse and choice of number of stages.
• Fluid-fuelled rocket engine cycles
• Analysis of rocket engine and its nozzle, including combustion & equilibrium.

Gas turbines /  turbojets

• Analysis of gas turbines: derivation of ideal air-standard Brayton cycle efficiency. Comparison to cycle with non-isentropic turbomachinery.
• Analysis of turbojet in flight with fully-expanded propulsion nozzle. - Calculate the propulsive efficiency and the need for turbofans or turbo props

Turbofans

• Analysis of a turbofan engine
• Selection of fan pressure ratio
• Worked examples session based around Cumpsty's New Efficient Aircraft.

Turbomachinery

• Principles of turbomachinery & Euler work equation
• Flow and work coefficient, specific speed and choice of turbomachinery type
• Use velocity triangles to predict characteristic map for a compressor - stall and choke limits.
• The axial turbine
• The axial compressor

Propellers and turboprops

• Actuator disc description of propellers.
• Propeller characteristics and how to select propellers for applications (particularly in the context of UAVs)

Teaching and learning methods

Teaching methods will include lectures and laboratory demonstrations.

Learning activities include directed reading, problem solving, report writing.

Resources & Reading list

Internet Resources

NASA Website.

Summative

This is how we’ll formally assess what you have learned in this module.

Referral

This is how we’ll assess you if you don’t meet the criteria to pass this module.

Repeat

An internal repeat is where you take all of your modules again, including any you passed. An external repeat is where you only re-take the modules you failed.

Repeat Information

Repeat type: Internal & External