Laval nozzle introduction

Laval nozzle is the most commonly used component of rocket and aero engines. It consists of two tapered tubes, one for contraction and the other for expansion. Laval nozzle is an important part of the thrust chamber. The front half of the nozzle shrinks from large to small toward the middle to a narrow throat. The narrow throat then expanded outward to the bottom of the arrow. The gas in the arrow body flows into the front part of the nozzles under high pressure, passes through the narrow throat and escapes from the back part.

This structure allows the velocity of the airflow to vary with the cross-sectional area of the jet, accelerating the airflow from subsonic to sonic to transonic. That's why they call it a transonic nozzle.

Because it was invented by the Swede Laval, it is also called the "Laval nozzle". Analyze the principle of the Laval nozzle. The gas flow in the rocket engine moves backwards through the nozzle and enters the A of the nozzle under the action of the combustor pressure. In this stage, the movement of gas follows the principle of "when the fluid moves in the pipe, the flow velocity at the small section is large, and the flow velocity at the large section is small", so the flow is constantly accelerated. By the time it reaches the narrow throat, the flow rate has exceeded the speed of sound. A transonic fluid, on the other hand, no longer moves faster at a smaller cross section than at a larger one. Instead, it moves faster at a larger cross section. In B, the gas flow is speeded up further, to 2-3 km/s, or 7-8 times the speed of sound, creating a huge thrust.

The Laval nozzle actually acts as a velocity enhancer. In fact, not only is the rocket engine, the missile nozzle is also such a horn shape, so the Laval nozzle in weapons have a very wide range of applications.