A converging-diverging nozzle, often referred to as a de Laval nozzle, is a type of nozzle designed to accelerate fluid flow. It has a narrow throat where the cross-sectional area decreases (converging section) and then expands (diverging section). This design allows the fluid to reach supersonic speeds as it exits the nozzle. These nozzles are commonly used in various applications, including rocket engines and jet propulsion systems. By converting pressure energy into kinetic energy, they efficiently increase the velocity of gases, making them essential for achieving high thrust in aerospace engineering.