Propulsion Fundamentals AERO 3030
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This 4 page Class Notes was uploaded by Madyson Kuhn on Wednesday September 23, 2015. The Class Notes belongs to AERO 3030 at Middle Tennessee State University taught by Terry Dorris in Fall. Since its upload, it has received 249 views. For similar materials see /class/212969/aero-3030-middle-tennessee-state-university in Aerospace Engineering at Middle Tennessee State University.
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Date Created: 09/23/15
Study Guide Final Exam Propulsions l P PP Equot gt 9 5 HH HO Causes of Vapor Lock vapor moisture in the Carburetor can only handle liquid causes the engine to not be able to emulsify the gas and locks Two Centrifugal ElementEither a Double entry or a Single entry OHMsLawElxRquot quot 39 quot g quot39 Flat Part of PropellerBlade face Boyle39s LawStates that the volume of any dry gas varies inversely with the absolute pressure sustained by it the temperature remaining is constant quotPquot FactorRight hand side descending blade will generate more AOT and have a tendency to turn left Torque EffectThe form of air resistance tends to bend the propeller blade in a direction that is opposite to the direction of rotation Ignition in a RecipEngine To accomplish this the aircraft battery furnishes electrical power to operate a starter which through a series of gears rotates the engine crankshaft This in turn actuates the armature of the magneto to produce the sparks for ignition of the fuel in each cylinder After the engine starts the starter system is disengaged and the battery no longer contributes to the actual operation of the engine Carburetor Ice IndicationGradual loss of engine speed a loss of MAP or both without changing the throttle Pressure Carburetor Chamber A Critical Altitudeis the highest level at which an engine will maintain a given horsepower output What happens to the turbine engine thrust with a decrease in exhaust nozzleThe thrust would be comparatively low and the direction of flow would not be properly controlled Volumetric Ef ciencythe ratio of the volume of the fuelair charge burned by the engine at atmospheric pressure and temp to the piston displacement Compression Event Duration Top dead center and bottom dead center Power LapLagValve LapLag Opening or closing of the intake or exhaust valves after TC or BC is called valve lag The opening or closing of the intake or exhaust valves before BC or TC is called valve lead H 0quot H l H 00 H LO NN HO N N NNNN GUIbu NN DON Turboprop Developing Reason provides the most efficient power source for aircraft operating speeds of 300450 mph Great fuel burn of any gas turbine engine O470Fuel injected outboard engine 470 cubic in ofdisplacement When do you feather a propellerWhen you want to stop the rotation of the propeller that is making drag feathering reduces drag Feathered blade is in an approximate inlineof flight position streamlines with the line of ight mostly constant speed props RecipEngine OilOil pumps gear gear rotor and vain Wet sump tank is cheap and is common Dry sumps have more advantages oil not in engine no capacity level etc Spark Plugs are in what Circuitlgnition Circuit Auxiliary Ignition Methods ignition booster booster magneto high tension coil to which primary current is supplied from a battery or a vibrator which supplies intermittent direct current from a battery directly to the primary of the magneto Another devise is used for increasing the high tension voltage of the magneto for startup is called an impulse coupling Magneto is off when groundedYes if the P lead points are grounded the magneto is grounded Piston stroke Valve position Engine Displacement Supersonic Inlet The inlet lip is sharpened to minimize the performance losses from shock waves that occur during supersonic flight For a supersonic aircraft the inlet must slow the flow down to subsonic speeds before the air reaches the compressor Reaction engine is most effective duringSupersonic speeds Turbine bleed air usages are In civil aircraft bleed air39s primary use is to provide pressure for the aircraft cabin by supplying air to the Environmental Control System Additionally bleed air is used to keep critical parts of the aircraft such as the wing leading edges icefree Bleed air is used on many aircraft systems because it is easily available reliable and a potent source of power For example air turbine starters used to start large jet engines are much smaller and lighter than an electric motor of equivalent power output Bleed air for starting is provided by an on board Auxiliary Power Unit APU or an external huffer if the APU is inoperative Once a single engine is started its bleed air can be used to drive the starter on the remaining engines Lavatory water storage tanks are pressurized by bleed air that is fed through a pressure regulator Even the outside air probe on some aircraft utilizes bleed air to drive a N LO W O U H U N WWW U39lhw WWW LDOONG39A h 0 h H hh LON venturi pump to draw outside air in to a temperature sensor chamber Early jet aircraft even used bleed air to drive the gyroscopes in their cockpit artificial horizons High bypass turbo fan advantagesGreater efficiency and reduced noise and with no propeller control issues Thermal Ef ciencyis the heat valve or heat energy output of the engine divided by the heat energy input fuel consumed BHPTHP TD constant is 4715 so MPG35 MPH70 70352 247lS943 94328263HP Fuel Injection AdvantagesFreedom from vaporization icing thus making it unnecessary to use carburetor heat except under bad atmospheric conditionsMore uniform delivery of fuelair mix To each cylinderreduction of maintenance problemsnstant acceleration of engine after idling with no tendency to stallncreased engine efficiency Detonation is caused byafter normal ignition the explosion of the remaining air fuel mix due to above normal combustion chamber pressure or temp Highest pressure in a turbine engine isThe outlet of the compressor What is the of air going through a turbine engine used for combustion Cowl FlapsCan control the temp of the engine They are located at on the engine cowling Sometimes manually operated by means of a switch that controls the actuating motor or by means of thermostatically Highest turbine engine temp isLocated in the turbine nozzle and can get up to 2000 degrees How long before oil pressure indication on a recip in cold weather305 Rich mix causesA decrease in power Inertia StarterA crank that stores the energy as the fly wheel spins and then when triggered its released to start the engine Impulse Coupling Coil spring that keeps energy and runs instead of magneto at low speeds to keep magneto from fowling Magneto AdvantagesDemands little maintenance Hotter spark selfcontaining unit Most common Carburetor Float Carb Capacitor function in magnetoThe component in a magneto ignition system that prevents the breaker points from burning and also aids the rapid collapse of the current flow in the primary circuit could also be condenser What does a turbine engine do to the air traveling through itcompresses the air pressure mixes with fuel and sparked 45 Hypergolic FuelCombo of fuel and oxidizer that ignite spontaneously on contact used as rocket propellant
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