1.
WHICH OF THE FOLLOWING TYPES OF ENGINE DOES NOT USE ATMOSpHERIC AIR FOR COMBUSTION
Correct Answer
A. ROCKET
Explanation
Rockets do not use atmospheric air for combustion because they carry their own oxidizer, typically liquid oxygen, which allows them to burn fuel in space where there is no air. Unlike pulsejets and ramjets, rockets can operate in the vacuum of space where there is no atmosphere to provide oxygen for combustion. Therefore, rockets are the only type of engine listed that does not rely on atmospheric air for combustion.
2.
WHAT EFFECT DOES A DIVERGENT DUCT HAVE ON AIRFLOW
Correct Answer
A. AN INCREASE IN PRESSURE AND DECREASE IN VELOCITY
Explanation
A divergent duct is designed to gradually increase the cross-sectional area of the duct. As the cross-sectional area increases, the velocity of the airflow decreases while the pressure increases. This is because the conservation of mass principle states that as the area increases, the velocity of the fluid must decrease to maintain the same mass flow rate. Additionally, according to Bernoulli's principle, as the velocity decreases, the pressure increases. Therefore, a divergent duct causes an increase in pressure and a decrease in velocity of the airflow.
3.
DURING SUPERSONIC FLIGHT WHAT MAJOR AIRCRAFT COMPONENT CAN NOT WITHTAND SUPERSONIC VELOCITY AIRFLOW
Correct Answer
B. THE ENGINE
Explanation
During supersonic flight, the major aircraft component that cannot withstand supersonic velocity airflow is the engine. The intense airflow at supersonic speeds puts excessive stress on the engine components, leading to potential damage or failure. The tail and intake are designed to handle supersonic airflow and are specifically built to withstand the high speeds and pressures associated with supersonic flight.
4.
IN AN AXIAL-FLOW ENGINE, BY WHAT MEANS IS HIGH-VELOCITY , LOW PRESSURE AIR CONVERTED TO LOW-VELOCITY, HIGH PRESSURE AIR
Correct Answer
A. ACTION OF SINGLE INTAKE DIFFUSER
Explanation
The correct answer is the action of a single intake diffuser. In an axial-flow engine, the high-velocity, low-pressure air is converted to low-velocity, high-pressure air through the use of a single intake diffuser. The diffuser slows down the incoming air and increases its pressure by expanding the flow area, allowing for a more efficient compression process. This conversion is necessary for the engine to operate effectively and produce the desired thrust or power.
5.
WHAT IS THE MOST SERIOUS DISADVANTAGE OF AXIAL-FLOW COMPRESSOR
Correct Answer
C. HIGH TENDENCY TO STALL
Explanation
The most serious disadvantage of an axial-flow compressor is its high tendency to stall. Stalling occurs when the airflow through the compressor is disrupted, leading to a loss of compression and reduced efficiency. This can result in a decrease in engine performance and potentially damage the compressor blades. Stalling is a critical issue that needs to be carefully managed in order to maintain the proper functioning of the compressor and overall engine performance.
6.
WITH REFERENCE TO AXIAL-FLOW ENGINE THE ANGLE OF ATTACK IS THE ANGLE AT WHICH THE AIRFLOW
Correct Answer
A. STRIKES THE ROTOR BLADES
Explanation
The angle of attack in an axial-flow engine refers to the angle at which the airflow strikes the rotor blades. This is an important factor in determining the efficiency and performance of the engine. By adjusting the angle of attack, the engine can optimize the airflow and generate more thrust. Therefore, the correct answer is "STRIKES THE ROTOR BLADES."
7.
WHAT THREE ENGINE OPERATING PARAMETERS CAUSE THE AIRFLOW ANGLE OF ATTACK TO VARY
Correct Answer
B. ENGINE, RPM, COMPRESSOR-INLER TEMP AND COMPRESSOR DISCHARGE PRESSURE
Explanation
The airflow angle of attack is influenced by three engine operating parameters: engine RPM, compressor-inlet temperature, and compressor discharge pressure. These factors affect the amount and speed of air entering the engine, which in turn affects the angle at which the air flows over the aircraft's wings. Therefore, changes in these parameters can cause the airflow angle of attack to vary.
8.
ENGINE CHOKING REFERS TO WHICH OF THE FOLLOWING TERMS
Correct Answer
B. STALL DUE TO AN EXCESS VOLUME OF AIR IN THE REAR OF COMPRESSOR
Explanation
Engine choking refers to a condition where there is an excess volume of air in the rear of the compressor, causing the compressor to stall. This can occur due to various reasons such as a blockage in the air intake, a malfunctioning valve, or a problem with the fuel-air mixture. When the compressor stalls, it disrupts the airflow and reduces the engine's power output, leading to a decrease in performance or even engine shutdown. Therefore, the correct answer is "STALL DUE TO AN EXCESS VOLUME OF AIR IN THE REAR OF COMPRESSOR".
9.
INLET GUIDE VANES CHANGE THE DIRECTION OF THE AIR ENTERING AND LEAVING THE COMPRESSOR IN WHAT MANER
Correct Answer
B. BY SWIRLING IT AS IT ENTERS AND STRAIGHTENING IT OUT AS IT LEAVES
Explanation
Inlet guide vanes change the direction of the air entering and leaving the compressor by swirling it as it enters and straightening it out as it leaves. This is done to optimize the airflow and improve the efficiency of the compressor. By swirling the air as it enters, the vanes create a swirling motion that helps to evenly distribute the air across the compressor blades, improving the overall performance. As the air leaves the compressor, the vanes straighten it out to ensure a smooth and uniform flow, reducing turbulence and pressure losses. This helps to maximize the compressor's efficiency and output.
10.
BLEED AIR FOR UNLOADING THE COMPRESSOR DURING STARTING , COCKPIT PRESSURIZATION AND HEATING, ENGINE ANTI-ICING, FUEL TANK , PRESSURIZATION AND VARIOUS OTHER PURPOSES IS TAPPED FROM WHICH OF THE FOLLOWING SOURCES
Correct Answer
B. DIFFERENT STAGES OF THE COMPRESSOR DEPENDING ON THE PRESSURE AND TEMPERATURE NEEDED
Explanation
Bleed air for various purposes such as unloading the compressor during starting, cockpit pressurization and heating, engine anti-icing, fuel tank pressurization, etc. is tapped from different stages of the compressor depending on the pressure and temperature needed. This means that the specific stage of the compressor is selected based on the requirements of the system that needs the bleed air. Different stages of the compressor can provide different levels of pressure and temperature, allowing for flexibility in meeting the specific needs of each system.
11.
WHAT IS THE PRIMARY FUNCTION OF THE COMBUSTION SECTION
Correct Answer
A. TO PROVIDE IGNITION
Explanation
The primary function of the combustion section is to provide ignition. This means that it is responsible for initiating the combustion process by igniting the fuel-air mixture. The combustion section contains components such as spark plugs or igniters that produce a spark or flame to ignite the mixture. Once ignited, the fuel-air mixture will burn and release energy, which is used to power the engine or generate heat. Therefore, providing ignition is the main purpose of the combustion section.
12.
APPROXIMATELY WHAT % OF AIR ENTERING THE COMBUSTION CHAMBER IS MIXED WITH FUEL FOR COMBUSTION
Correct Answer
C. 25%
Explanation
Approximately 25% of air entering the combustion chamber is mixed with fuel for combustion. This means that a quarter of the air is combined with the fuel to create the necessary mixture for combustion to occur.
13.
APPROXIMATELY WHAT % OF AIR ENTERING THE COMBUSTION CHAMBER SERVES AS FLAME CONTROL
Correct Answer
B. 75%
Explanation
Approximately 75% of the air entering the combustion chamber serves as flame control. This means that a significant portion of the air is used to regulate and maintain the combustion process, ensuring that the flame is stable and efficient. The remaining 25% of the air likely serves other purposes such as providing oxygen for complete combustion and cooling the combustion chamber.
14.
WHICH OF THE FOLLOWING IS NOT A BASIC ELEMENT OR SYSTEM OF COMBUSTION CHAMBER
Correct Answer
C. AIR POLLUTION EMISION REDUCTION
Explanation
Air pollution emission reduction is not a basic element or system of a combustion chamber. A combustion chamber is primarily composed of a casing, which provides structural support and contains the combustion process, and an inner liner, which protects the casing from the high temperatures generated during combustion. Air pollution emission reduction, while important in the overall design and operation of a combustion system, is not a direct component of the combustion chamber itself.
15.
WHICH OF THE FOLLOWING IS NOT A BASIC TYPE OF COMBUSTION CHAMBER
Correct Answer
C. BASKET-CHAMBER
Explanation
The question asks for a type of combustion chamber that is not considered a basic type. The options given are annular, can-annular, and basket-chamber. The correct answer is "basket-chamber" because it is not a commonly recognized or basic type of combustion chamber. The other options, annular and can-annular, are well-known and widely used types of combustion chambers in various industries.