TURBINE NOTE CARDS Flashcards
What can cause an attendant breakdown of stable, steady flow of air through the compressor?
Answer:
An excessive pressure rise required in the compressor. (ANA page 126)
The axial flow compressor must operate relatively close to the stall-surge limit to obtain ________.
Answer:
Peak efficiency. (ANA page 124)
What is the function of the turbine section?
The function of the turbine section is to extract energy from the combustion gases and furnish power to drive the compressor and accessory section. (ANA 112)
Generally speaking, the specific fuel consumption _________ steadily with altitude until the Tropopause is reached.
Answer:
Decreases (ANA page 121)
What happens during a compressor stall once there is an attendant break down of stable air?
As stall occurs, the pressure rise drops and the compressor does not furnish discharge at a pressure equal to the combustion chamber pressure. As a result, a flow reversal and backfire takes place. (ANA 127) THE HIGH PRESSURE IN THE COMBUSTION CHAMBER WANTS TO GO TO THE LOW PRESSURE IN THE COMPRESSOR AREA.
The ________ is responsible for increasing the pressure in order for the compressor section to furnish high pressure air.
Answer:
Diffuser (ANA page 110)
The function of the tailpipe or exhaust nozzle is to discharge the exhaust gases at _____.
Answer:
The highest possible velocity to produce the greatest momentum change and thrust. (ANA page 114)
Which section of the turbine engine has the highest velocity of airflow?
Answer:
Exhaust section. (ANA page 114)
The turbine engine usually has a strong preference for _______ RPM to produce _____ specific fuel consumption.
Answer:
High, low. (ANA page 119)
What would happen if the velocity of the air delivered by the compressor was too high?
Poor combustion and likelihood of a flameout would occur. The diffuser aids in the reduction of velocity and an increase of pressure.
When considering the operation of a gas turbine engine, what provides the most important restriction to the operation of the turbojet engine?
Answer:
The limiting exhaust gas temperatures. (ANA page 125)
What type of energy is extracted from the combustion gases by the turbine blades?
Answer:
Mechanical energy. (ANA page 113)
The ___________ receives the high pressure discharge from the compressor and introduces approximately one half of this air into the immediate are of fuel spray.
Answer:
Combustion chamber. (ANA page 111)
What happens to pressure within the combustion chamber?
Pressure remains constant within the combustion chamber. The process is essentially a constant pressure addition of heat energy. (ANA page 107)
The highest pressure in a turbine engine can be found in which section?
Answer:
Compressor section. (ANA page 115)
Where is the diffuser located within a typical turbine engine?
Answer:
The diffuser is located aft of the compressor section. (ANA page 107)
Which section is considered the most critical element of a turbojet engine?
Answer:
Turbine section. (ANA page 113)
What is the recommended method to recover from a compressor stall?
Recovery is accomplished by quickly reducing throttle setting, lowering the airplane angle of attack, and increasing airspeed and reducing altitude if high altitude is a contributing factor. (ANA page 126)
The combustion of fuel causes a large change in ______________ and ____________.
Answer:
Temperature, volume. (ANA page 107)
During a compressor stall, what causes an immediate rise in exhaust gas temperatures?
Answer:
The increase in compressor power required which tends to reduce RPM and further reduces airflow and increases fuel flow. (ANA page
What happens to the volume and pressure of the air aft of the diffuser?
Answer:
Volume is decreased, and pressure is increased. (ANA page 107)
The diffuser converts ________ energy into _______ energy.
Answer:
Kinetic, static pressure energy. (ANA page 111)
The purpose of the inlet or diffuser is to?
Answer:
Reduce the velocity and increase the pressure of the air entering the compressor section.(ANA page 107)
Which section of the turbine engine is subjected to the highest temperatures?
Answer:
Turbine inlet. (ANA page 114)
Which section is responsible for furnishing the combustion chamber with specific quantities of high pressure air?
Answer:
Compressor section. (ANA page 107
High pressure energy of the combustion gases is converted into what type of energy?
Answer:
Kinetic energy. (ANA 112)
Which section is the first section in which work is extracted from the turbine engine process?
Answer:
The turbine section. (ANA page 107)
What two ramifications does the effect of temperature have on thrust output?
- At takeoff, a high ambient temperature reduces thrust because of low density and low mass flow.
- Loss of thrust due to reduced mass flow, thrust, and fuel flow is reduced further because of the high compressor inlet temperature.
What are the three common causes for compressor stalls?
- A malfunctioning fuel control or governing apparatus.
- Power inlet conditions are typical at high angles of attack and sideslip.
- Very high altitude flight produces low compressor reynolds numbers. Very high altitudes reduce the maximum pressure ratio of the compressor. (ANA page 126)
Which one factor strongly affects the performance of the turbojet engine?
Answer:
Altitude (ANA page 119)
The turbine engine is limited by the turbine inlet ______________.
Answer:
Temperature (ANA page 114)
When at ______ like during takeoff, an increase in velocity will reduce the velocity change through the engine without a corresponding increase in mass flow and the available thrust will decrease.
Low velocity. At higher velocity, the beneficial ram helps to overcome this effect, and the available thrust no longer decreases but increases with speed. (ANA page 116)
At what point does airflow begin to accelerate in a turbine engine?
Air begins to accelerate after leaving Burner
Where is the airflows greatest acceleration?
Exhaust
What happens to pressure at the diffuser?
Volume decreases and pressure increases
Which part of a turbine engine is the hottest?
Hottest temp is turbine inlet.
What would happen if the velocity of the air delivered by the compressor was too high?
Poor combustion and likelihood of a flameout would occur. The diffuser aids in the reduction of velocity and an increase of pressure. (ANA page 113)
PRIMARY JOB OF COMPRESSOR
The primary function of the compressor is to supply enough air to satisfy the requirements of the combustion section. Specifically, the compressor increases the pressure of the airflow from the air inlet duct and directs it to the burners in the quantity and at the pressures required. A secondary function is to supply compressor bleed air to operate various components throughout the engine and aircraft
Air from the compressor entering the burner section will be divided into two types: primary and secondary air
___________ percent is primary air, and it is mixed with fuel for combustion
The remaining____ percent is secondary air, it flows around the chamber and through the small holes and louvers to cool the thin walls and control the flame. This unburned air can also be used to help cool the turbine
25
75
Stator vanes come before the rotors in the turbine section. The function of the stator vanes is twofold.
First, it prepares the airflow from the combustion chamber for the harnessing of power by the turbine rotor.
Second, the stators deflect the gases at a specific angle in the direction of turbine wheel rotation
The ________ section is the most highly stressed part of the engine. Not only must it operate at temperatures nearing 2,000° F (monitored in the cockpit), but it must do so while undergoing severe centrifugal loads imposed by rotational speeds of over 10,000 rpm. The higher the temperature the turbine section can bear, the higher the thrust that can be produced
turbine
The exhaust cone collects the exhaust gases discharged from the turbine assembly and gradually converts them to a________.
solid jet
Where does bleed air come from and what is it used for?
A stage in compressor (varies w/ engines). It is used for pressurization, heating, air conditioning, anti-ice, pneumatics.
5 SECTIONS OF A GAS TURBINE ENGINE
1 INLET 2 COMPRESSOR 3 DIFFUSER 4. COMBUSTION 5. TURBINE 6. EXHAUST
3 MAIN SECTIONS
GAS GENERATING SECTIONS
- COMPRESSOR
- BURNER/COMBUSTION
- TURBINE
IN THE COMPRESSOR MECHANICAL ENERGY IS CONVERTED INTO _______________.
PRESSURE ENERGY
