Galactic Tech Empire

Chapter 248 Turbocharging
As the only high-speed rotating machinery in an important assembly of rocket engines, the turbo pump of space rockets is known as the heart of liquid rocket engines in the industry.

Its working principle is similar to that of a car's turbocharger. It uses gas to drive the turbine to rotate to drive the pump to pressurize the low-pressure propellant in the rocket tank and deliver it to the gas generator and thrust chamber for combustion in real time.

Liquid rocket engine turbopumps are designed with great emphasis on light weight and high performance, and many turbopump components are designed close to the limit of the state of the art.

Therefore, in order to make the turbopump reliable and adaptable to the requirements of launch vehicles or spacecraft, many problems must be solved.

For example: In order to meet the performance and weight requirements, the turbo pump must work at high speed, so it must have bearings and seals that meet the life requirements at high speed.

In addition, the pump must have a high-suction inducer to reduce tank pressure and weight.

The aerospace agencies that are currently engaged in kerosene liquid oxygen staged combustion cycle engines are Dongtang and Maoxiong.

But there are many kinds of staged combustion cycle engines. Sunland and Mili use hydrogen-oxygen engines, and they generally use high-pressure oxygen supplementation.

The core of the rocket is the engine, and the core of the engine is the fuel pump, because the rocket engine itself is just a very simple cavity, the key issue is how to provide it with enough fuel.

The way to provide fuel is the circular way.

From the current development trend, the cycle mode of a rocket engine is roughly: extrusion, expansion, gas turbine, and electric push.

The gas turbine can be divided into several types such as gas generator, staged combustion, and full flow staged combustion.

They all use rocket fuel to drive a small engine, and then drive a turbo pump to pump the fuel out.

The gas generator draws a portion of the fuel to drive the gas turbine, which then drives the turbine to pump more fuel to the main engine.

The exhaust gas produced by the gas turbine is directly discharged from the body. The Merlin engine of the Space Exploration Company is based on this principle. Because the used fuel does not participate in the secondary cycle, it is also called an open cycle.

A more advanced stage is the staged combustion cycle. The exhaust gas generated by the gas turbine will enter the main engine together with other fuels and burn again to avoid waste.

The fuel and oxidant supplied to the gas turbine can be mixed in two ways, one is excess fuel, that is, rich combustion; the other is excess oxidant, that is, oxygen-enriched combustion.

Among them, the exhaust gas after oxygen-enriched combustion flows into the main engine and needs to be supplemented with more fuel, so it is called afterburning.

More advanced than the staged combustion cycle is the full flow staged combustion cycle.

Unlike pumping part of the fuel to drive the turbine, the full flow means that all the fuel is burned once to drive the turbine, which can provide more powerful turbine power, and the combustion effect is better after mixing in the main engine.

The Raptor engine currently developed by Space Exploration Corporation is this kind. The fuel is methane. It uses two pre-combustion chambers of rich combustion and oxygen-rich combustion respectively, and then merges in the main combustion chamber.

High pressure refers to the performance index of the engine.

The rocket generates thrust by jetting backwards. The jet speed is determined by the pressure inside the combustion chamber of the engine (chamber pressure). High pressure is good.

And the high chamber pressure means that the turbo pump must have enough pressure to send fuel into the engine, so the performance of the turbo pump engine will definitely be higher.

东唐航天系统的YF100的室压是18兆帕（1兆帕等于10标准大气压），属于高压，作为对比，猎鹰9的梅林发动机不到10兆帕。

However, Mili's unique skill is low-pressure high-performance, and the F1 engine of the Saturn V is a low-pressure gas generator cycle.

Before he knew it, Huang Haojie's electric car had arrived at the gate of the hydrogen-oxygen engine research institute.

Several security personnel rushed over.

"Boss, I'll notify Director Qin immediately."

"No need, I'll just go in."

The hydrogen-oxygen engine research institute is surrounded by mountains and rivers, and more than half of the space is in the mountains or underground.

Having heard Huang Haojie coming, the director Qin Tongxing hurried over.

"Boss, welcome to come and guide the work."

"Where is the development progress of the hydrogen-oxygen engine?"

"We are working on a magnetic levitation bearing system."

"Go and see."

"plz follow me."

A group of people came to a laboratory that was developing magnetic suspension bearings.

A huge electric motor is running crazily.

"This motor is an experimental machine we developed using room temperature superconductors and strong magnetic repulsion materials." Qin Tongxing pointed to the motor and introduced it.

The difference between the turbine system of a space rocket engine and the turbine system on a car is the power source of the turbine.

Automotive turbine systems can be divided into three types according to the source of power: exhaust gas turbine, mechanical turbine, and electric turbine.

Exhaust gas turbine, as the name implies, is to use the exhaust gas from the exhaust pipe to drive the turbine; while the mechanical turbine is to use the transmission system of the car to drive the turbine; as for the electric turbine, it is to use the battery to drive the motor to drive the turbo.

There are generally two types of turbine systems on space rocket engines.

One is a small engine turbine and the other is an electric motor turbine.The former is more common, and the latter is currently in the research and development stage because it is difficult for the motor to achieve a speed of more than 10,000+.

What the hydrogen-oxygen engine research institute is developing is the electric motor turbine system.

"How much speed has it reached?"

"15 revolutions per minute."

Huang Haojie nodded in satisfaction. It is very rare to be able to achieve this speed.

At present, the exhaust gas turbine or mechanical turbine can reach 12 to 16 revolutions per minute.

But the motor can run at most 1 revolutions per minute. This is still a DC motor. If it is an AC motor, it can run at most 3000 revolutions per minute.

Why is the RPM of the motor so low?
Rotor dynamics determines that when the linear speed of the rotor reaches a certain speed (such as 150m/s), the centrifugal stress exceeds the strength of the rotor and some parts of the rotor are separated.

This is a common problem faced by all high-speed motors.

Simply put, it is the mechanical strength that limits the speed.

In addition, for brushed DC motors, the excessively high speed will cause serious friction between the commutator and the brushes, and the arc will also increase significantly. The heat accumulated by the two will quickly burn the brushes.

The bearing at the end of the motor also has a certain speed limit, so that the speed has a bottleneck.

After all, it is a matter of materials.

If the material meets the requirements, theoretically the rotational speed of the DC motor can be close to infinity.

Material science is exactly the strength of Yinhe Technology, so with the application of various new materials, the motor turbine of the Hydrogen-Oxygen Engine Research Institute can reach a speed of 15 revolutions per minute.

"I am very pleased that you can achieve this level, let's make persistent efforts."

"The boss and everyone will definitely not be disappointed." Qin Tongxing said quickly.

"How much can the chamber pressure of the combustion chamber be achieved now?" Huang Haojie continued to ask.

“21～22兆帕是极限，我们预计将涡轮系统的转速提升到40～50万转每分钟，这样就可以将燃烧室的室压提升到30兆帕左右。”

"Can the combustion chamber withstand a pressure of 30 MPa?"

"No problem, we used nano-stainless steel material, which is not only very strong, but also can withstand extreme high temperature of 2700 degrees Celsius. After testing, the combustion chamber of the new material can withstand the ultimate pressure of 59 MPa." Qin Tongxing explained.

"The speed of the motor is increased. You can communicate and cooperate with the Institute of Electrical Machinery."

"In this regard, we often communicate and cooperate with them."

"Ok!"

Accompanied by Qin Tongxing, Huang Haojie continued to investigate at the Hydrogen-Oxygen Engine Research Institute.

(End of this chapter)