Turbine Design Test Review Notes

Turbine Engine Design Test Review

Thrust Indication in Turbofan Engines

  • The percentage of RPM, EPR (Engine Pressure Ratio), and an unspecified instrument are used to indicate the thrust output of a turbofan engine.

Best Engines for High Ram-Pressure Ratio

  • Turbojet engines are the best for high ram-pressure ratio applications.

Ground Clearance Consideration

  • Ground clearance is critical for low-wing aircraft equipped with turboprop engines.

Turboprop Speed Limit

  • Turboprop aircraft are generally speed-limited to 500500 mph.

Function of Gas Generator in Free Turbine Turboprop

  • In a free turbine turboprop, the gas generator section's primary function is to produce high-velocity gases to drive the power section.

Turbofan Engine Ducts

  • The turbofan engine has two ducts for fan exhaust air: a short duct and a long duct.

Primary Airflow in Turbofan Engines

  • Core engine air is also referred to as the primary engine air in a turbofan engine.

Thrust Sensitive Signal System

  • The thrust-sensitive signal system automatically feathers the propeller in the event of engine failure.

Medium Bypass Turbofan Ratio

  • A medium bypass turbofan engine has bypass ratios ranging from 2:12:1 to 3.9:13.9:1.

Ultrahigh Bypass Fan Engine

  • The ultrahigh bypass prop fan engine is still in experimental stages.

Turbine Section Function

  • True: The low-pressure turbine section drives the fan section of a turbofan engine and can drive several of the first few stages of the core compressor.

Primary Airflow Path in Turbofan Engine

  • In a turbofan engine, the primary airflow passes through the core of the engine.

Turbofan Engine Efficiency

  • The turbofan engine's efficiency is increased because it converts more fuel energy into pressure energy for thrust.

Torquemeter Purpose

  • The primary purpose of the torquemeter in a turboprop or turboshaft engine is to indicate the power developed by the engine.

Gas Turbine Engines Delivering Power to a Shaft

  • Turboprop and turboshaft engines are gas turbine engines that deliver power to a shaft.

APU Turbine Engine Type

  • A turboshaft turbine engine is often used for APUs (Auxiliary Power Units).

Lubrication Oils for Turbine Engines and APUs

  • Synthetic oils are used for lubrication in both turbine engines and APUs.

APU Starter Types

  • DC electrical starters are the most common type of starters for APUs.

Turbojet Engine Designation

  • The turbojet engine is also referred to as the pure jet.

Thrust Creation in Turbojet Engines

  • Turbojet engine thrust is created by highly accelerating a small mass of air, and all airflow passes through the compressor and turbine section.

APU Generator System Output

  • False: APU generator systems can supply both AC and DC power to the aircraft.

Turboprop/Turboshaft Output Shaft Location

  • False: The output shaft on a turboprop or turboshaft can exit the engine on either the inlet or outlet side.

Turboprop Engine Components

  • A reduction gearbox, torquemeter, and condition lever are three components that a turboprop engine uses that other turbine engines do not use.

Common Engine Core Usage

  • True: Engine manufacturers of turbojet, turbofan, turboshaft, and turboprop engines could use the same engine core in their construction.

APU Power Usage

  • False: APU electric and/or pneumatic power can be used both on the ground and in the air.

Best Engine for High-Altitude, High-Speed, Long-Distance Flights

  • The turbojet engine is best for high-altitude, high-speed, long-distance flights.

Specific Weight Comparison

  • The turbojet has the lowest/lightest specific weight compared to other turbine engines.

Turbine Stage Impact

  • True: Adding more turbine stages to turboprop or turboshaft engines would cause an increase in energy extracted from the hot, high-velocity gases passing through the turbine section.

Free Turbine Gas Generator Components

  • The free turbine gas generator section installed on some turboprop engines consists of a compressor, combustor, and compressor's turbine.

TSFC Characteristics

  • The TSFC (Thrust Specific Fuel Consumption) is lowest at low altitudes and low airspeeds with the turboprop engine.

Power Control on Turboprop Engines

  • The fuel lever and the condition lever must be coordinated to control the power output on a turboprop engine running under normal conditions.

Propeller Braking System

  • The propeller brake system prevents the propeller from windmilling when the engine is shut down.

Transonic Fan Blade Development

  • Development of the transonic fan blade allows for the use of longer fan blades at high engine speeds.

Thrust Indicator in High Bypass Turbofan Engines

  • Newer high-bypass turbofan engines use N1 as the primary indicator for the thrust output of the engine.

APU Installation Location

  • APUs are normally installed in the tail/back/aft section of the aircraft.

Compressor Type in APUs

  • The centrifugal compressor is the most common type of compressor used in APU construction.

APU Power Levers

  • The power levers in the cockpit are not indications of the power output of the APU.

Low Compressor Purpose in APUs

  • The primary purpose of the low compressor in an APU equipped with a free turbine is to provide air for the aircraft pneumatic system.

Free Turbine Connection

  • False: The "free turbine" is not mechanically connected to the compressor in a turboshaft or turboprop engine.

Thrust Percentage Developed by Fan Section

  • 8080% of the thrust developed by high-bypass turbofan engines comes from the fan section.