Difference Between Impulse and Reaction Steam Turbines
3 Answers
Impulse and reaction steam turbines differ in their working principles and characteristics. The specific differences are as follows: 1. Principle: An impulse steam turbine is one where steam expansion occurs only in the nozzle. In the moving blades of an impulse turbine, the steam does not expand to perform work but merely changes its flow direction. A reaction steam turbine is one where steam expansion occurs not only in the nozzle but also in the moving blades. The moving blades of a reaction turbine are subjected not only to the force generated by the impact of the steam flow but also to the force produced by the expansion and acceleration of the steam within the moving blades. 2. Characteristics: Impulse Steam Turbine: Steam primarily expands in the nozzle, with little or no expansion in the moving blades, mainly changing the flow direction. Modern impulse turbines have a certain degree of reaction, meaning a very small portion of steam expansion occurs in the moving blades, providing some acceleration to the steam flow, but they are still classified as impulse turbines. Reaction Steam Turbine: The moving blades are not only subjected to the impulse force from the high-speed steam flow exiting the nozzle but also to the reaction force as the steam leaves the blade row. In other words, a reaction turbine utilizes both impulse and reaction principles to perform work.
Hi, I've always been fascinated by engine technology, especially after tinkering with automotive turbochargers a few times. The core difference between impulse and reaction turbines lies in fluid dynamics: impulse turbines work like water striking blades—fluid hits them in one forceful impact to induce rotation, with pressure loss occurring at the nozzle. In contrast, reaction turbines allow fluid to expand between blades, gradually releasing pressure to drive rotation. In practical applications, automotive turbochargers predominantly use impulse designs because high-speed exhaust gas striking blades delivers higher efficiency and quicker throttle response. Reaction turbines are more common in large-scale systems like hydroelectric plants, where maintenance is more complex. Understanding these principles helps me fine-tune racing performance—for instance, paying closer attention to airflow impact patterns when selecting the right turbocharger.
Years of car repair experience have taught me that impulse turbine blades are simple and easy to maintain because the fluid directly impacts the blades, which is common in automotive turbochargers—just cleaning carbon deposits will suffice. In contrast, reaction turbine blades have special shapes where the fluid expands and propels, making them prone to wear and more costly. The difference affects daily maintenance: repairing impulse turbines is quicker and time-saving, while reaction turbines require precise calibration. In vehicles, I often encounter turbine failures, mostly due to insufficient fluid impact, so I recommend car owners to regularly check exhaust flow velocity.
