Simple Analysis of Centrifugal Compressor Impeller

As the main rotating component in the compressor, the core function of the impeller is to increase the pressure of the gas through centrifugal force.

The impeller is usually installed inside the gearbox, specifically, it is fixed to the horizontal pinion shaft. This configuration is quite common, especially in some equipment, you will see only one impeller installed on each pinion shaft. However, there are also cases where two impellers are installed on each pinion shaft for specific needs or design considerations, as shown in the figure below.

The air enters from the middle of the impeller tip, is then accelerated and directed to the lower end by the blades, and finally thrown out from the end of the blades in a tangential direction. In this process, the increase in air speed is the starting point for the centrifugal compressor to increase pressure.

The design of the impeller blades is key to the compressor's performance, including their depth, length, and angle. At the same time, the material strength and amount of the impeller are also particularly important because these impellers can rotate at speeds of up to 30,000 RPM or even higher. At such high speeds, blade breakage is absolutely unacceptable because it may lead to the complete destruction of the compressor.

In today's engineering and manufacturing fields, impellers are usually made of a single raw material blank, which is finely processed by a five-axis milling machine to finally present the ideal characteristics designed by engineers according to user needs. The design of the impeller must take into account two goals: on the one hand, it must ensure that it meets specific flow and pressure requirements; on the other hand, it must also pursue the highest efficiency in energy utilization. Excellent engineering design is the key to creating a compressor that is both reliable and efficient.

The choice of blank material is wide and can include carbon steel, stainless steel, etc. In certain cases, such as the specific gas that the compressor needs to handle, special materials are also selected. For example, for high-end centrifugal compressors, stainless steel is usually selected instead of carbon steel when compressing air in order to extend the service life of the components.