15.01 - Fundamentals Flashcards
(22 cards)
Give a definition of energy
Gives us the capability to perform work.
It’s a quality something has after work has been done to it.
Has the unit joules.
Give a definition and the formula for potential energy.
PE = MGH
It is energy while a body is at rest.
Give formula and doing kinetic energy.
KE = 0.5 x M x V^2
Energy in motion.
Newtons 1st law
Law of inertia.
Object in motion stays in motion…
Newtons 2nd law
F = MA
Shows the interplay between force and motion.
Thrust is proportional to the mass of the airflow through the engine multiplied by the acceleration of the air.
Newtons 3rd law.
Action and re-action.
The Brayton cycle.
Suck, squeeze, bang, blow.
Constant pressure cycle. Or. Continuous combustion cycle.
Give the 4 ideal changes of state.
Isobaric
Isochoric
Isothermal
Isentroic
What stages of the brayton cycle are isentropic.
The intake and compression stages are isentropic compression.
The exhaust stage is isentropic expansion.
What stages of the brayton cycle are isobaric heating.
Combustion.
Force and unit for force.
F=MA
In newtons or pounds.
1Lb =4.448N
Formula for work and units.
Work = force x distance.
Unit = joules (J)
1J =1 N⋅m
Formula and unit for power.
P = work / time.
P = FxD/T
Unit = watt (W) 1W=1Nm
Give one positive and one negative about piston engines.
More efficient on fuel.
Performance decreases with altitude.
How does the power : weight ratio of piston engines change as they get bigger.
Decreases.
Pros and cons of turbojet engines.
Pros
- relatively simple design
- capable of very high speeds
- takes up smaller frontal area.
Cons
- high fuel consumption
- loud
- poor performance at low speeds.
- limited range and performance.
Pros and cons of turbofan engines.
Pros
- fuel efficient
-quieter then turbojets
-streamlined appearance.
Cons
- heavier than turbojets
- larger frontal area than turbojets.
- inefficient at very high altitudes.
Pros and cons of turboprop engines.
Pros
- very fuel efficient.
Most efficient at mid altitudes.
Cons
-limited forward speed
- gearing systems are heavy and prone to breaking down.
Designed to produce shaft horsepower only.
Charactoristics of turbo shaft engines.
Usually an APU
Higher power : weight than piston engines.
Smaller than piston engines.
Loud
Complex gears can wear down.
Advantagfor the manufacturer of modular engines construction.
Rotating modules ca be pre-balanced
Fewer spare engines needed in stock
More flexibility when changes are made to individual parts
The main modules can be stored and transported easily.
Advantages for the engine operator of modular engines change as construction.
No re-balancing after a module change.
Less need for spare parts.
Modules removed and replaced with a minimum disturbance to other modules.
Engine materials.
Strong, lightweight, economical to manufacture.
Titanium, steel, nickel, ceramic, composite, CRES, cobalt.
