Flow in Turbomachinery I

 

Content

Turbomachines play an important role in many parts of our lives. They are used as engines of almost all modern aircraft or in the field of power generation. Furthermore they are an important component in process industry plants. Hence, higher demands are placed on efficiency, emissions and performance. In order to meet these challenges, a deep understanding of the thermodynamics, aerodynamics and structural mechanics of turbomachinery is required.

In addition to the design of the thermodynamic cycle, the aerodynamic design of the individual components is essential for the development of efficient turbomachinery. In the lecture "Turbomachinery Flow I" a basic understanding of the special aerodynamics in subsonic compressors and turbines shall be given. The characteristics of transonic flows as well as further knowledge in this subject area will be conveyed in the follow-up lecture "Turbomachinery Flow II".

As an introduction to the topic, frictionless profiles are considered using potential flow theory. On the basis of this approach, a basic understanding of the profile design and the lift of individual profiles should be conveyed. Based on this, the theory is extended from a single profile to a cascade in order to derive effects such as incidence, profile thickness and curvature on the blade flow in a turbomachine. In addition, the knowledge gained so far is extended to include frictional influences such as boundary layer flows and transition, which have a major influence on the real flow of a turbomachine. The influence of geometry-related (e.g. blade pitch) and operation-related (e.g. inflow conditions) changes on the profile flow will also be discussed. Finally, in the last part of the lecture, the more complex 3D flow effects (e.g. secondary flows) will be categorized and analyzed. Furthermore, the lecture provides measures to influence them by using three-dimensional blade design for compressors and turbines.

 

Topics

• Potential flow theory
• Potential flow for single airfoil and cascade
• Frictional flow around blades
• Subsonic axial compressor
• Subsonic axial turbine