Tutorial — 2D Flow in Axial Flow Turbines — Lesson 5

This lesson covers the fundamentals of axial flow turbines, including their thermodynamics, two-dimensional cascade analysis, and 3D analysis. It delves into the different types of axial turbines, such as impulse and reaction turbines, and their applications in aero engines, marine, and land-based power plants. The lesson also explains the concept of degree of reaction, velocity triangles, and the various losses that occur in axial turbines. It further discusses the methods of calculating efficiency for axial turbines and the performance characteristics of axial turbines. The lesson concludes with a tutorial session on solving problems related to axial flow turbines.

Video Highlights

02:46 - Definition and calculation of degree of reaction.
04:03 - Explanation of total to static efficiency and total to total efficiency.
08:19 - Explanation of velocity triangle for a reaction turbine stage.
10:14 - Calculation of specific work done, Mach number, axial velocity, total to total efficiency, and stage reaction for a single stage gas turbine.
31:27 - Calculation of blade loading coefficient, pressure ratio of the stage, and flow angles for a mixed flow turbine.
43:42 - Calculation of number of stages required for a multi-stage axial turbine.

Key Takeaways

- Axial turbines are commonly used in aero engine applications and marine as well as land-based power plant applications due to their efficiency and convenience.
- Axial turbines can be classified as impulse turbines, where the entire pressure drop takes place in the nozzle, and reaction turbines, where the pressure drop is shared between the nozzle and the rotor.
- The degree of reaction is a crucial concept in understanding axial turbines.
- Velocity triangles are essential tools in understanding the flow in axial turbines.
- Axial turbines experience various losses, including two-dimensional losses and 3D losses like secondary flows and leakage losses.
- The efficiency of axial turbines can be calculated using two commonly used definitions: total to static efficiency and total to total efficiency.
- The performance characteristics of axial turbines are significant in relation to the engine as a whole.