Answer

Design Analysis

1. Sketch a fan blade from a HBTF and identify the main parts of it?

Adapted from: Bennett et al (2015)

1. B. What are the main phenomena of a jet engine

compressor?

The principal phenomena of the jet engine compressor is that the combustion of air and fuel at normal/usual atmospheric pressure will not yield sufficient energy that can generate useful work (Thai Techniques, 2015). The amount of energy produced by combustion is proportionate to the air mass consumed and its pressure. As such, a higher pressure is required to increase the combustion cycle’s efficiency.

1. What techniques do we use to overcome the negative effects of the phenomena?

Jet engines rely on the multistage of centrifugal compressor to generate a higher pressure that can enhance the combustion cycle’s efficiency (Thai Techniques, 2015). This goal is achieved by combining the centrifugal compressor and axial flow compressor.

The centrifugal compressor functions by taking in or sucking the outside air close to the hub and circling it using an impeller. The impeller is made of an aluminum alloy and directs the air toward the compressor’s outer circumference (Thai Techniques, 2015). The air velocity is increased by the high speed of rotation of the impeller.

According to Thai Techniques (2015), the compressor has three major parts that include the impeller, diffuser, and compressor manifold. Air abandons the impeller at a higher speed, and flows via the diffuser that converts the kinetic energy of high velocity to a high pressure energy of low velocity. Besides, the diffuser also directs the flow of air to the compressor manifold that serves as a collector ring. As such, the high pressure and low velocity of the air is sufficient to be employed in the engine’s burner section.

In order to enhance the efficiency of the compressor, the blades are developed as lifting surfaces, just as in the case of the propeller blades or aircraft wings. The effect of the cascade is a primary factor in determining the angle of attack, blade spacing in the design of the compressor blade, and airfoil section. Thai Techniques (2015) asserts that the blade should be developed to withstand/tolerate high aerodynamics loads and centrifugal forces to which they are exposed. The clearance between the rotating blades and their external case is also significant. The rotor assembly turns/rotates at a higher speed, and should be rigid, well balanced, and well-aligned.