Powerplant Word Scramble
|
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
| Question | Answer |
| Shrouded turbine blades have what advantages over traditional blades? | -Reduced vibration -Improved airflow characteristics |
| What design feature do some turbine blades have to reduce vibration and improve airflow? | They are shrouded |
| In a Dual-Spool Compressor, at what speed does the Low-Speed compressor operate? | It seeks its own best operating speed (The High pressure rotor is governed for speed) -Altitude increases, load decreases, low-pressure rotor increases speed. |
| What variables affect the inlet air density on a turbine engine? | -Speed of aircraft -Altitude -Ambient Temp. |
| Aircraft speed, Altitude, and ambient temperature will all affect the Inlet Air _ of a turbine engine. | Inlet Air Density |
| What does a Dump Valve do, and why? | It cuts off fuel to the nozzles, and drains the manifolds. -Prevents fuel boiling off from residual engine heat. |
| What does "Field Cleaning" an engine mean? | Procedure for removing accumulated dirt/deposits on compressor blades. |
| The procedure for removing accumulated dirt deposits on compressor blades is called? | Field Cleaning |
| What are 3 Types of Turbine Blades (not how they're mounted). | Impulse, Reaction & Impulse-Reaction. |
| What is the purpose of an Automatic Bleed Valve? | Vents some of the high-pressure air overboard to prevent a compressor stall/Surge. -Otherwise, air could "pile up" in high pressure stages and inhibit airflow through engine. |
| What is one function of the Nozzle Diaphragm in a turbine engine? | It directs/deflects the gases to a specific angle in the direction of turbine rotation. -Gases will hit the turbine blades @ desired angle. |
| Main advantage of an Axial-Flow compressor vs. Centrifugal. | Higher peak efficiency. |
| Should, and how would you blend a Turbine blade? | It is possible, if: -Parallel to the Length of the blade -Use Smooth contours to minimize stress points. |
| What does an Inlet Guide Vane assembly do for an Axial-Flow compressor? | Directs (Guides*) air into 1st Stage rotor at the proper angle. |
| The airfoils that DO NOT rotate in an Axial-Flow compressor are called _? | Stator Vanes |
| Stator Vanes (Move/Do Not move) in a turbine engine? | Do Not move (Think "Stationary" |
| Continued/Excessive heat, and Centrifugal Force on rotor blades will likely cause what? | Creep (Permanent Elongation of blades) |
| What is Blade Creep? What causes it? | Permanent Elongation of turbine blades, caused by continued/excessive heat and Centrifugal Force. |
| Hot Section inspections are normally required when? | On a Time/Cycle basis. |
| What factors affect a Turbine engine's Thermal Efficiency? | -Turbine Inlet Temp -Compression Ratio -Turbine & Compressor Efficiency |
| Turbine Inlet temp, Compression Ratio and Turbine/Compressor Efficiency all affect the _ _ of a Turbine Engine? | Thermal Efficiency -*Think: Temp that goes in, how much it compresses (heat generated), and how efficiently it does so. |
| Which has higher Pressure Ratios? (Axial/Centrifugal) flow compressors. | Axial, with better efficiency. |
| One advantage of Centrifugal-flow Compressors is a High _ _ -per-stage. | Pressure Rise (The pressure rises higher per stage). |
| What is the primary function of the Turbine Assembly in a Turbojet Engine? | Turns the Compressor -Ignited gases spin the turbine, which drives the compressor up front, making the engine self-sustaining. |
| What is Standard Atmosphere? (Temperature F/C) | 15 deg. C 59 deg. F |
| What is Standard Pressure? | 29.92 in/mercury |
| What is Standard Pressure/Atmosphere used in for Turbine Engines? | Calculating the power of an engine. |
| When an engine with multiple-stage compressors is operated @ high altitudes, the low pressure rotor will (Increase/Decrease) in speed as the compressor load (increases/decreases) | Increases, Decreases |
| The Low-Pressure rotor in a split compressor will increase speed when the compressor load _? | Increases |
| Stator Vanes serve what purpose in an Axial-flow compressor section? | The decrease the velocity/prevent swirling |
| Stator Vanes convert the Velocity from the Rotors into what kind of energy? | Pressure (Think: Rotors speed it up, Stators raise the pressure) |
| Which turbine engine offers the greatest advantages for starting flexibility, and improved high-altitude performance? | Split-Spool, Axial-flow |
| The Fan on a Dual-Axial Compressor, Forward-Fan engine is connected to ? | The Low-Pressure compressor -*The fan is big enough that some of the air passes through the outside of the engine casing |
| If the fuel/air mixture on a turbine is too weak (assuming normal airflow), the result may be_? | A Lean Die-out |
| Turbine engine Main Bearing Oil Seals are usually what type? | Labyrinth and/or Carbon Rubbing |
| Labyrinth or Carbon Rubbing seals are usually used where in a Turbine Engine? | Main Bearing Oil Seals |
| If a turbine engine can't reach T/O EPR before the EGT limit is reached, this could indicate _? | The compressor may be contaminated or damaged. |
| What is the proper starting sequence for a turbojet engine? | Starter, Ignition, Fuel |
| What areas of a turbine engine are susceptible to dirt? | Casings, Inlet guide vanes, compressor blades *Extreme heat tends to prevent coating on the turbine blades. |
| Engine driven propellers impart a (large/small) amount of acceleration to a (large/.small) mass of air. | Small acceleration to a large mass of air. *As opposed to a Turbojet/fan engine, which imparts a large acceleration to a small mass of air. |
| What is "Galling" | The transfer of metal from one surface to another. |
| Severe rubbing of turbine engine compressor blades will usually cause what? | Galling |
| Who establishes mandatory replacement times for critical engine components? | Engine Manufacturer |
| What type of combustion chamber Case & Liner are removed/installed as ONE unit? | Can-Type (Outer case/housing with perforated stainless combustion chamber/liner inside) |
| When subsonic air flows through a Convergent Nozzle, the velocity _? | Increases, for subsonic airflow. (Bernoulli's Principle) *Area decreases, velocity increases, pressure decreases* |
| When subsonic air flows through a Divergent Nozzle, the velocity _? | Decreases, for subsonic airflow. (Bernoulli's Principle) *Area Increases, Velocity decreases, pressure increases* |
| When Supersonic air flows through a Divergent Nozzle, the velocity _? | Increases (Opposite of subsonic air, where Increasing area increases pressure/decreases velocity.) |
| Possible cause of Turbine Engine High oil temp, with no change in power setting parameters? | Main bearing distress *Bearing is overheating, and heat is transferring to the oil* |
| Two basic parts of a Centrifugal Compressor? | Impeller and Diffuser Impeller-speeds up the air/adds energy Diffuser-Slows the air/increases pressure |
| The majority of the air passing through the combustion chamber of a turbine engine is used for what? | -Support combustion -Cool the engine |
| A Turbine Hot Section is most susceptible to what kind of damage? | Cracking, from extreme temps and vibrations |
| During low-thrust ops, what can help stabilize compressor airflow? | Variable guide vanes and/or compressor bleed valves. |
| What do Variable guide vanes and compressor bleed valves help prevent? | Compressor stalls @ low thrust. |
| Explain Variable Guide Vanes purpose/operation. | Prevent compressor stalls @ low thrust. -Compressor RPM high relative to air flowing through, compressor blade AOA will become too high and surge/stall can occur. They adjust to the proper angle. |
| Explain how Automatic Compressor Bleed valves prevent compressor stalls. | Bleed air valves (connected to fuel control) open to reduce back-pressure, letting more air into the engine |
| At what stage in a turbine engine are gas pressures the greatest? | At the compressor outlet. |
| The compression ratio of an Axial-flow compressor is a function of the _? | Number of compressor stages. |
| What is the advantage of a Dual Axial-Flow compressor? | Higher compression ratios |
| What is the primary function of a Turbine Engine Exhaust cone? | Straightens/collects exhaust gases into a solid exhaust jet. |
| The "Brayton cycle" is also known as the constant _ cycle. | Constant Pressure |
| Explain the Brayton Cycle principle. | Cycle of energy used by a turbine engine. -Energy added to air by burning the fuel -Volume of air increases -Pressure remains relatively constant. |
| In a turbine engine, combustion occurs at a constant (volume/pressure/density) | Pressure (Brayton Cycle) |
| Why are lead/wax/grease markings not used on Turbine engine hot sections? | They contain carbon, which when exposed to high temperatures, will cause granular embrittlement and lead to cracking. |
| In turbine hot sections, what are safe ways to mark components? | Layout dye, Felt tip markers, Chalk |
| What does Newton's Second "Law of Momentum" State? | Acceleration of an object depends on the Force acting on it, and it's mass. (Remember: the 1st Inertia law covers objects in motion/at rest). |
| If ball/roller bearings are found to have any magnetism, what must be done? | They must be degaussed before using them again. (They would attract ferrous particles and be damaged) |
| What are two methods of removing dirt deposits on a turbine engine? | Fluid wash Abrasive grit blast |
| What 3 main sections make up a gas turbine engine? | Compressor, Combustor and Turbine |
| A compressor stall is caused by a (low/high) angle of attack through the first compressor stages. | High |
| What two factors affect the AOA of an axial-flow compressor blade? | Velocity of the air through the engine RPM of the compressor |
| What is the purpose of a diffuser in a turbine engine? | In a Centrifugal-flow engine, the diffuser acts like the Stators. -The Impeller accelerates the air (velocity) -Diffuser converts velocity to pressure. |
| After a Fuel Control Unit has been replaced on an engine, what must be done? | Re-Trim the engine |
| Why are turbine blades more susceptible to damage than compressor blades? | Exposure to high operating temperatures |
| What are the 3 basic types of Combustion sections used on turbine engines? | Multiple Can, Annular, Can-Annular |
| The purpose of the turbine section is to drive the _ section. | Compressor Section |
| First-Stage turbine blades are found to have stress rupture cracks on the leading edges. This is a sign of a _ condition. | Overtemperature condition. |
| What is the most |
Created by:
avandermey
Popular Aviation sets