Gas Turbine Engineering

Compressor and gas turbine Characteristics: This material is presented here to familiarize the reader with the behavior of these machines, classified under the broad term “turbomachinery.” Pumps and compressors are used to produce pressure; turbines produce power. These machines have some common characteristics. The main element is a rotor with blades or vanes, and the path of the fluid in the rotor may be axial, radial, or a combination of both. There are three methods of studying the elements of turbomachinery operation. First, by examining forces and velocity diagrams, it is possible to discover some general relationships between capacity, pressure, speed, and power. Second, comprehensive experimentation can be undertaken to study relationships between different variables. Third, without considering the actual mechanics, one can use dimensional analysis to derive a set of factors whose grouping can shed light on overall behavior. The analysis presented in this chapter shows the typical performance diagrams one can expect from turbomachines. Off-design performance is also important in understanding trends and operating curves.