How is energy converted within a turbine?

It is a process in which the thermal energy of steam is converted into the internal energy of the mechanical metal parts, the potential energy of steam is converted into kinetic energy, and mechanical energy is generated!

A steam turbine is a rotary prime mover that uses steam to generate power; it converts the thermal energy of steam into mechanical work, usually through either the impulse principle or the reaction principle. Impulse type: in the nozzle, the steam is cooled and depressurized to generate a high-speed steam stream. The high-speed steam stream emerging from the nozzle flows into the moving blades. Within these blades, the steam flow changes its speed and direction due to the resistance exerted by the blades; as a result, the steam flow exerts a reaction force on the blades, pushing them to move and converting part of the kinetic energy into mechanical work that drives the rotation of the impeller. The flow passage of the reaction steam turbine still consists of stages of stationary blades and stages of rotating blades; within the stationary blades, the steam flow behaves similarly to that in nozzles, with pressure decreasing, volume expanding, and velocity increasing ； Its moving blades are also designed as steam channels with a gradually narrowing cross-section, allowing the steam flow to experience further pressure reduction, expansion, and acceleration within these blades.

A turbine is a rotary prime mover that converts thermal energy into mechanical energy using steam at certain temperatures and pressures as the working medium (thermal energy of steam – kinetic energy – mechanical energy). 1 Impulse principle: When a moving object comes into contact with another object, it is hindered, causing a change in its speed and direction; at the same time, it exerts a force on the object that hinders its motion, and this force is generally referred to as an impulse force. The magnitude of this force depends mainly on the mass of the moving object and the change in its velocity. For example, when steam from the boiler passes through valves and nozzles into the turbine, it is slowed down and changes direction due to the obstruction caused by the turbine’s moving blades, flowing then toward the stationary blades of the next stage of the turbine; the moving blades are also subjected to the force exerted by the steam. 2 Reaction principle: Reaction force is generated when an object that was originally at rest or moving at a low speed suddenly gains a large increase in velocity as it passes by another object, such as a rocket. Therefore, turbines are classified into pure impulse type, reaction type, combined impulse-reaction type, and impulse type with a slight degree of reaction, etc.; the classification is not very clear.

During energy conversion, high-temperature and high-pressure superheated steam flows through the turbine, where its temperature and pressure decrease as it expands to perform work; thermal energy is thus converted into mechanical energy, which is then transmitted from the turbine shaft to drive various equipment. Since the steam does work on the outside, it is a isentropic expansion. Below is an excerpt from the book describing the working principle of a steam turbine: The working principle of a steam turbine varies depending on the effect of the steam on the impeller. They can be divided into two categories: one is the working principle of impulse steam turbines, and the other is the working principle of reaction steam turbines. a. Working principle of the impulse steam turbine: In one stage of an impulse steam turbine, the working process is divided into two phases. The first phase is the preparation stage: the steam expands within the nozzle, during which its pressure decreases, its volume increases, and its velocity – as well as its kinetic energy – rises. The second stage of the working process, which is also the main stage, takes place within the moving blades. At this stage, the steam flowing along the surface of the moving blades exerts a force on them, pushing the blades to move in a circular motion; the kinetic energy of the steam is thus transferred to the blades, turning it into mechanical energy that drives the rotation of the rotor. This is how an impulse steam turbine works. b. Working principle of the reaction steam turbine: In a reaction steam turbine, steam first expands in the nozzles before entering the rotor blades. Since the cross-sectional shape of the edges between the rotor blades along the direction of the steam flow is essentially the same as that of the edges between the stator blades, the steam continues to expand within the rotor blades. As the airflow flows along the inner arc of the moving blade, its direction changes; as a result, the moving blade is subjected to both impact forces and the reaction force resulting from the high-speed expulsion of steam from the blade. In this way, the force acting on the moving blade is the sum of the impulse force and the reaction force. Strictly speaking, the working principle of a reaction steam turbine utilizes both the impulse principle and the reaction principle.

Hehe, I’ve learned it. But regarding what was said on the second floor about heat energy being converted into internal energy in mechanical systems, does heat energy actually get converted into mechanical energy? It should do, right?