2.3.3 Engine design problem

Abstract

1. The purpose of this project is to explore how changes in a parts of an engine effect the thrust/weight ratio.

2. We needed to make 4 changes to initial settings and see how they impacted the thrust/weight ratio. The speed and altitude of the plane should stay fixed at reasonable values.

3. We spent 2 class days on this project

Concepts

Definitions:

• Engine net thrust
  • The amount of force the engine outputs
• Fuel flow rate
  • The amount of fuel that flows through the engine in an amount of time
• Engine air flow rate
  • The amount of air that flows though the engine in an amount of time
• Engine weight
  • The weight of the engine
• Thrust to weight ratio
  • The amount of thrust that the engine outputs in relation to its weight
• Specific fuel consumption
  • The amount of thrust the engine outputs in relation to the fuel used.
• Fuel-to-air-ratio
  • The amount of fuel required to create combustion of the gas
• Engine pressure ratio(EPR)
  • Total pressure ratio across the engine, pressure of output air divided by pressure of input air
• Engine temperature ratio(ETR)
  • total temperature ratio across the engine, temperature of output air divided by temperature of input air
• Gross thrust
  • Total thrust of an engine
• Ram drag
  • difference between gross thrust and net thrust
• Nozzle pressure ratio(NPR)
  • Nozzle pressure to static pressure
• Engine thermal efficiency
  • The amount of heat an engine can produce in relation to the heat-equivalent heat inputted.
• Nozzle exit velocity(V exit)
  • The speed of the air going out of the nozzle
• Free stream dynamic pressure (q0)
  • kinetic energy per unit volume of fluid
• Specific impulse (ISP)
  • Total impulse outputted per unit volume of fuel.
• Nozzle exit pressure (Pexit)
  • The pressure of the air exiting the nozzle
• Fan nozzle exit pressure (P fan exit)
  • The pressure of the air exiting the fan
• Compressor face Mach number (M2)
  • The mach number at the pace of the compressor
• Variation of total pressure and temperature through the engine
  • How the temperature and pressure changes throughout the engine
• Overall engine efficiency
  • How efficient the engine is

Trial 1, with all parts at full efficiency is the best trial. The net thrust of the build was the greatest so it's able to output the most driving force. Furthermore, it's ram drag was slightly less than the others making it have less resistance. Its TSFC is also the lowest, meaning that it needs less fuel to run. Similar to net thrust, it has a higher ISP so it outputs more impulse. It also has the highest Pexit and Vexit meaning the exiting air will be able to propel the plane better, explaining the higher net thrust and ISP values. In conclusion, the first trial created the best engine to propel a plane or jet.