Jet Engine Theory And Design

The statement is true because it accurately defines the terms "mass" and "weight". Mass refers to the quantity of matter an object contains, while weight is the force of gravity acting on that mass. Therefore, the statement correctly states that mass is the quantity of matter and weight is the pull of gravity on that quantity of matter.

Rockets do not use atmospheric air for combustion because they carry their own oxidizer, usually in the form of liquid oxygen, which allows them to burn fuel in space where there is no air. Unlike pulsejets and ramjets, which rely on the intake of atmospheric air for combustion, rockets are self-contained and can operate in the vacuum of space.

Bleed air for various purposes 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. The compressor has multiple stages, each operating at different pressures and temperatures, allowing for the extraction of air at the desired conditions for different purposes such as cockpit pressurization, heating, engine anti-icing, and fuel tank pressurization.

Work is the measurement of force times distance. This means that in order to calculate the amount of work done, we need to multiply the force applied to an object by the distance over which the force is applied. Work is a scalar quantity and is measured in joules. It represents the energy transferred to or from an object by means of a force acting on it.

The correct answer is "STALL DUE TO AN EXCESS VOLUME OF AIR IN THE REAR OF COMPRESSOR." Engine choking refers to a condition where the airflow through the engine is disrupted, leading to a loss of power or stall. In this case, the excess volume of air in the rear of the compressor causes a disruption in the airflow, leading to engine choking. This can occur due to various reasons such as a malfunctioning compressor or a blockage in the air intake system.

When the temperature increases, the kinetic energy of air molecules also increases. This causes the molecules to move faster and collide with each other more frequently and with greater force. As a result, the air molecules spread out further apart, leading to a decrease in air density. Therefore, the statement is true.

The correct answer is "BY SWIRLING IT AS IT ENTERS AND STRAIGHTENING IT OUT AS IT LEAVES". This means that the vanes in the compressor guide the air in a swirling motion as it enters the compressor, and then straighten it out as it leaves. This swirling motion helps to improve the efficiency and performance of the compressor.

The correct answer is FIR-TREE AND BULB. These are two common forms of blade roots used in various applications. The fir-tree root is shaped like a fir tree, with multiple protrusions that fit into corresponding slots in the rotor disc. This design provides good stability and resistance to centrifugal forces. The bulb root, on the other hand, is a rounded shape that allows for easy installation and removal of the blade. It provides a secure fit and helps in distributing the load evenly. Both forms of blade roots have their advantages and are commonly used in different types of blades.

Air pollution emission reduction is not a basic element or system of a combustion chamber. A combustion chamber is primarily composed of a casing and an inner liner. The casing provides structural support and contains the combustion process, while the inner liner helps to protect the casing from the high temperatures generated during combustion. Air pollution emission reduction, on the other hand, is a separate concern that involves implementing technologies and strategies to minimize the release of pollutants into the atmosphere. While important, it is not directly related to the basic elements or systems of a combustion chamber.

Power is the rate at which work is done or energy is transferred. It is a measure of how quickly a task can be completed or how much energy is used per unit time. Power is calculated by dividing the work done or energy transferred by the time taken. Therefore, power is the correct answer as it is directly related to the rate of doing work.

The correct answer is "NEWTONS 2D LAW" because Newton's second law of motion states that the acceleration of an object is directly proportional to the net force applied to it and inversely proportional to its mass. This law explains how the motion of an object changes when a force is applied to it, and it is commonly expressed as F = ma, where F is the net force, m is the mass of the object, and a is the acceleration.

Increasing compressor load through the use of variable-area exhaust nozzles is not considered by engine manufacturers as a corrective action for a front-end, low-speed, high-temp stall. This is because increasing the compressor load can potentially exacerbate the stall condition and lead to further damage to the engine. Installing a bleed valve in the middle of the rear portion of the compressor section is a common corrective action to alleviate the stall condition by reducing the compressor load.

The primary function of the combustion section is to burn the fuel-air mixture. This is where the fuel and air are mixed together and ignited to produce combustion, which generates the necessary heat and energy to power the engine.

In an axial-flow engine, high-velocity, low-pressure air is converted to low-velocity, high-pressure air through the action of stator blades at each stage of compression. Stator blades are stationary blades that are placed between rotating blades (rotor blades) in the compressor section of the engine. As the high-velocity air passes through the stator blades, it is redirected and its velocity is reduced. This redirection and reduction in velocity cause an increase in pressure, resulting in the conversion of high-velocity, low-pressure air into low-velocity, high-pressure air.

Energy is the correct answer because it is the capacity for doing work. Energy is the ability to cause change or perform work, and it exists in various forms such as kinetic energy, potential energy, thermal energy, etc. It is the fundamental concept in physics that describes the ability of a system to do work or transfer heat. Therefore, energy aligns with the given description of "capacity for doing work."

The given answer, "BASKET-CHAMBER," is not a basic type of combustion chamber. The other two options, "ANNULAR" and "CAN-ANNULAR," are commonly used types of combustion chambers in gas turbines. An annular combustion chamber consists of a ring-shaped design, while a can-annular combustion chamber consists of multiple individual combustion cans arranged in a circular pattern. However, a "basket-chamber" is not a recognized or commonly used type of combustion chamber in the field of gas turbines.

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A single air entrance is more advantageous than a dual air entrance system because it allows the aircraft to obtain maximum ram pressure. This means that the air entering the aircraft is at its highest possible pressure, which is important for various functions such as engine performance and aerodynamic efficiency. Having a single air entrance simplifies the design and manufacturing process of the aircraft, making it easier to produce. However, the main advantage mentioned in the question is the ability to obtain maximum ram pressure.

A divergent duct is designed to gradually increase the cross-sectional area of the airflow. As the airflow enters the divergent duct, the increase in area causes a decrease in velocity according to the principle of continuity. This decrease in velocity is accompanied by an increase in pressure, as stated by Bernoulli's principle. Therefore, the correct answer is that a divergent duct has the effect of increasing pressure and decreasing velocity of the airflow.

Approximately 25% of air entering the combustion chamber is mixed with fuel for combustion. This means that a smaller portion of air is combined with the fuel to facilitate the combustion process. The remaining percentage of air is likely used for other purposes such as cooling or dilution.

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 flame during the combustion process. By controlling the amount of air, the flame can be adjusted to achieve optimal combustion efficiency and ensure proper fuel combustion.

The profile of a compressor blade refers to its shape and design. In this case, the correct answer is "A cutout that reduces blade thickness." This means that the compressor blade has a specific cutout or indentation that is designed to reduce its thickness. This cutout helps to improve the aerodynamic performance of the blade and optimize its efficiency in compressing air. By reducing the blade thickness, the cutout allows for better airflow and reduces the chances of turbulence or drag, ultimately enhancing the overall performance of the compressor.

Jet engines use both simplex and duplex fuel nozzles. Simplex fuel nozzles have a single fuel spray pattern, while duplex fuel nozzles have multiple fuel spray patterns. The choice between simplex and duplex fuel nozzles depends on the specific requirements of the jet engine and the desired fuel distribution. Simplex fuel nozzles are commonly used in smaller jet engines, while duplex fuel nozzles are used in larger engines to achieve better fuel atomization and more efficient combustion.

Newton's 3rd Law states that for every action, there is an equal and opposite reaction. This means that when one object exerts a force on another object, the second object exerts a force of equal magnitude but in the opposite direction on the first object. In other words, any force exerted on an object will result in a force of equal strength but in the opposite direction on the object that exerted the initial force. This law explains the concept of interaction between objects and is fundamental in understanding the principles of motion and force.

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During supersonic flight, the major aircraft component that cannot withstand supersonic velocity airflow is the engine. Supersonic airflow creates extreme conditions of temperature and pressure, which can cause damage to the engine components. The high-speed airflow can lead to overheating, structural deformation, and failure of engine parts. Therefore, engines need to be specifically designed and equipped with materials and cooling systems that can handle the intense conditions of supersonic flight.

The disadvantage of the Axia-Flow compressor is that it requires high starting power needs. This means that it requires a significant amount of power to start and operate, which can be a disadvantage in terms of energy consumption and cost.

The correct answer is "ACTION ON A BODY THAT CHANGES ITS STATE OF MOTION". This definition accurately describes force as a physical interaction that causes a change in the motion of an object. It implies that force can either start or stop the motion of an object, or change its direction or speed. This definition aligns with Newton's second law of motion, which states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.

The purpose of compressor blade profiles is to allow the compressor blade tips to rub without causing serious damage. This means that the profiles are designed in a way that allows for a small amount of contact between the blade tips and the surrounding components, such as the casing, without causing significant wear or damage. This is important because the tips of the compressor blades can experience rubbing during operation due to factors like thermal expansion or manufacturing tolerances. By having specific blade profiles, the rubbing can be minimized and the overall performance and durability of the compressor can be improved.

The three parts of the MIL-STD-879 engine designation system are the type indicator, manufacturer symbol, and model indicator. The type indicator specifies the type or category of the engine, such as whether it is a reciprocating engine or a turbine engine. The manufacturer symbol identifies the specific manufacturer of the engine. The model indicator indicates the specific model or version of the engine. These three parts together provide a standardized way to designate and identify different engines according to their type, manufacturer, and model.

The RAM effect refers to the situation where more air is entering the engine intake than the engine can actually ingest. This can occur when the aircraft is flying at high speeds, causing a buildup of air pressure in front of the intake. The excess air can result in increased engine performance and power output.

Proper air entrance duct design is important to increase ram recovery while reducing pressure drops. Ram recovery refers to the ability of an aircraft to recover and utilize the kinetic energy of the incoming air. By designing the air entrance duct properly, the aircraft can effectively capture and utilize the kinetic energy, resulting in increased ram recovery. Additionally, reducing pressure drops in the duct helps to maintain a smooth and efficient airflow, allowing for optimal performance and fuel efficiency.

The most serious disadvantage of an axial-flow compressor is its high tendency to stall. Stalling occurs when the airflow through the compressor becomes disrupted, leading to a loss of efficiency and potentially causing damage to the compressor blades. This can result in a decrease in overall engine performance and reliability. Stalling is particularly problematic in axial-flow compressors due to their design, which relies on a delicate balance of airflow and pressure. Therefore, the high tendency to stall is a significant drawback of axial-flow compressors.

Horsepower is the correct answer as it is a unit of measurement used to quantify mechanical power. It is commonly used in the English measurement system to measure the power output of engines, particularly in the automotive and industrial sectors. The term "horsepower" originated from the work of James Watt, who compared the power output of steam engines to the work done by horses. It is still widely used today to describe the power of engines and motors.

Newton's 1st Law states that an object at rest will stay at rest, and an object in motion will stay in motion with the same speed and direction, unless acted upon by an external force. This law explains the concept of inertia, where objects tend to resist changes in their state of motion. It implies that if there is no net force acting on an object, it will either remain at rest or continue moving in a straight line at a constant velocity.

The angle of attack is the angle at which the airflow strikes the rotor blades. At this angle, the airflow becomes turbulent over the upper foil surface.

During the combustion process, the emission level of nitric oxide increases as the temperature increases. This is because at higher temperatures, the nitrogen and oxygen molecules in the air react more vigorously, leading to the formation of more nitric oxide. Nitric oxide is a harmful pollutant that contributes to air pollution and can have negative effects on human health and the environment.

The correct answer is 8 OR 10. The question asks about the total number of combustion liners used in a jet engine with a can-type combustion chamber. The answer 8 OR 10 suggests that there can be either 8 or 10 combustion liners used in such an engine. The exact number may vary depending on the specific design and model of the engine.

The solid-spool, axial-flow compressor provides greater starting flexibility and improved high-altitude performance. This type of compressor is designed with a solid rotor, or spool, that rotates within a stationary casing. It is known for its efficient airflow and ability to handle varying operating conditions, making it ideal for applications where starting flexibility and high-altitude performance are important. The solid-spool design allows for better control of the airflow, resulting in improved performance at high altitudes.