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The surprising secret of rocket engines: Why do they propel themselves through a vacuum?
In the process of space exploration, people are often curious about how rocket engines work. Unlike engines in the atmosphere, rocket engines can operate in a vacuum, allowing them to achieve amazing speeds, even breaking the limit of escape velocity. Why is this possible?
A rocket engine is a reaction engine that generates thrust by expelling reaction mass backwards in accordance with Newton's third law of motion.
Rocket engine propulsion is based on a simple principle of physics. They generate thrust by ejecting hot gases at high speeds. These gases are created by burning propellant stored inside the rocket, creating a high-pressure stream of gas. In this case, the rocket engines carry their own oxidizer, which means they don't rely on external air for combustion and can therefore operate in the vacuum of space.
Compared to other types of jet engines, rockets have the lightest weight and the greatest thrust, but the lowest propulsion efficiency.
The propulsion efficiency of a rocket engine is usually measured by its "specific impulse", which is the amount of thrust it can produce per unit of propellant. The higher the specific impulse value, the greater the thrust generated by the rocket engine when using the same weight of propellant. In addition, rocket propellants are vast and diverse, including solid propellants, liquid propellants and hybrid propellants, each with its own unique combustion characteristics and propulsion effects.
The design of the combustion chamber is crucial to the operation of a rocket engine. All propellants need to enter this combustion chamber at high pressure to ensure complete combustion. This requires various design approaches, such as using a turbopump to increase the propellant entry pressure, or automatically boosting the tank's internal pressure with high-pressure gas.
The design of the rocket nozzle can affect the thrust and operating efficiency of the engine. The most commonly used is the Delaware nozzle.
The expansion of hot gases through the nozzle can convert thermal energy into kinetic energy, which plays a vital role in the operation of rocket engines. The design of the nozzle affects the speed and pressure of the airflow, which in turn affects the overall thrust. Different nozzle configurations, such as variable nozzles, can even adapt to different ambient pressures to maintain optimal performance. In addition, propulsion operations in a vacuum also require consideration of lightweight design and airflow optimization, which are challenges in the development of modern rocket technology.
In order to improve rocket performance, various new nozzle designs can be used to adapt to different environmental changes.
However, the efficiency of a rocket engine in a vacuum depends on a variety of factors, including the properties of the propellant, the high temperature and pressure environment of the combustion process, and the proper design of the nozzle. The propulsion of a rocket comes not only from the velocity of the exhaust gases, but also from the pressure inside the combustion chamber. In a vacuum, this thrust changes as the ambient pressure decreases, affecting the rocket's overall performance.
With the continuous development of aerospace technology, in order to meet the needs of deep space exploration, scientists are also actively studying new rocket propulsion systems, such as electric propulsion and nuclear thermal propulsion. These emerging technologies provide new possibilities for future space travel. .
Future rocket propulsion systems may adopt new technologies to improve propulsion efficiency to meet the new challenges of space exploration.
In general, the principle of rocket engine propulsion in a vacuum not only relies on the laws of physics, but also involves technological improvements in many aspects. From the design of the combustion chamber and the choice of propellant to the shape and operation of the nozzle, every detail directly affects the performance and efficiency of the rocket. Such technical issues are worth our deep consideration: How will future rocket technology lead us to explore farther into space?
