An Introduction to Turbomachinery

Turbomachinery deals with the study of steam and jet engines that make up essentially the entire heavy-duty industry. It is an arrangement designed to convert kinetic energy into other forms of usable energy, depending upon the application of the unit.  

Turbomachinery covers industries from energy conversion to the aeronautical engineering sector. Because of its extensive use in the job market, getting qualified in turbomachinery is crucial for any engineering and diploma graduate. 

Follow this content to refresh the basics of turbomachinery, as well as its types and applications. 

 

Brushing up on the Basics

Turbomachinery can be defined as a machine that exchanges energy between a working fluid and the blades of a turbine. The main applications of turbomachinery are the use of turbines to produce hydroelectricity or in an aircraft jet engine. 

 

Classifications

Turbomachinery can be classified based on the following:

1. Based on the mode of energy transfer
2. Based on the working medium
3. Based on the type of flow
4. Based on the direction of flow

Based on the Mode of Energy Transfer

This type of machinery can be further classified into the following: 

• Power-Producing Machinery: Extracts energy from a fluid (e.g., turbines)
• Power-Consuming Machinery: Delivers energy to the fluid (e.g., pumps, compressors, blowers, etc.)

Based on the Working Medium

Machinery can be made to work with different types of fluids, each having its own unique properties. While fluids like water will make use of pumps and hydraulics, gases will make use of steam and gas turbines. 

Based on the Type of Flow

The two main types of flow are compressible and incompressible flows. Fluids like water and other liquids are considered incompressible, while gases are considered as compressible. 

Based on the Direction of Flow

The two flow directions are radial and axial, depending on the arrangement and orientation of the turbine blades. Radial flows are diverted in a perpendicular direction, while axial flows remain parallel after the energy conversion. 

 

Axial Flow System

As mentioned, in axial flow, the direction of the fluid is axial or parallel to the axis of rotation of the rotor. 

In the illustration, each batch of a stationary and rotating blade represents a stage of the compressor or turbine. The dotted line here represents the axis of the machine, while the arrow marks depict the fluid flow direction. 

In this diagram, the dotted lines again represent the axis, and the marked blades are alternating impeller and stationary blades. The arrow markings are indicating the flow direction. 

 

Radial Flow System

In this system, the path of the fluid is radial (90 degrees) from its point of contact with the blade, with respect to the axis of rotation of the same. 

 

The Impeller Proposition

An impeller transfers energy from the motor to the fluid in a centrifugal pump. It is a rotating component that accelerates the fluid being pumped outwards from the center of rotation. 

As the illustration suggests, there are two main types of impellers: open and closed type. 

• In the open type, the fluid flow has a better degree of freedom after it contacts the impeller, but the amount of energy lost is quite high.
• In the closed type, the fluid flow has limited choices to pass through after it has made contact with the impeller. The amount of energy lost is considerably low when compared to the previous case.

 

Steam and Gas Turbines

The two primary turbomachinery devices are steam and gas turbines. These two are used extensively in mostly all walks of engineering. They are the main powerhouses and driving forces that generate the amount of energy needed for the process to develop. 

The shaft output generated by the steam turbines is used to produce electricity, while the gas turbines are primarily used for the production of jet engines. They function based on the combustion of a mixture of air and fuel inside the combustion chamber of the modern-day jetliners. 

The above-labeled diagram shows a simple steam turbine power plant. The idea is to combust fuel and pass it through the turbine to generate mechanical energy from the kinetic energy of the hot gases. The process is a closed cycle as the remaining amount of fuel-air mixture is passed back onto the system. 

Step 1

The boiler has an exothermic reaction, while the turbine helps to expand the gases. Ideally, these processes are isentropic, suggesting that there are no losses during the entirety of the cycle. But as is known, no thermodynamic cycle is 100% efficient, and so even this system concurs losses dissipated as heat and sound energy. 

Step 2

As the steam heats up the air-fuel mixture, it gains a tremendous amount of pressure. This high-pressure stream of gases then enters the turbine section where the pressure and velocity drop significantly. It also rotates the turbine by transferring its energy to the blades. 

This pressure drop takes place in stages and is reduced by a fixed factor that depends on the number of vanes present on the turbine axis. 

Step 3

The turbine is connected to an alternator and many other devices that detect and convert the pressure into electrical energy. This also includes the use of transformers and other conversion devices.

Step 4

As mentioned, once the gases come back to their ambient conditions, they are condensed, thus completing the cycle. 

 

Conclusion

Turbomachinery is one of the main types of machinery that was responsible for the rise of industries during the great Industrial Revolutions. 

The technology involved behind this device is rather simple but has come a long way since. Thanks to the constant developments by the great minds in the field of engineering, turbomachinery now has a diverse range of uses across industries. 

To know more about the basics of turbomachinery and its scope in the industry, visit Skill-Lync today.

 

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