FAA Powerplant Written Practice Test

What is meant by a double entry centrifugal compressor?

1. A compressor with dual impellers

2. A compressor with vanes on both sides of the impeller

3. A compressor operating at double the standard pressure

4. A compressor using dual-phase fluids

The correct answer is: A compressor with vanes on both sides of the impeller

A double entry centrifugal compressor refers to a design in which air enters the impeller from both sides, rather than from just one side as in a single entry design. This configuration allows for enhanced efficiency and performance by effectively utilizing the energy imparted by the impeller across a broader surface area and increasing the volumetric flow rate. The dual-sided entry helps distribute the workload and can result in a reduced size of the compressor while delivering the same or increased performance compared to traditional designs. In this configuration, the design can also help minimize the risk of generating excessive back pressure, which can improve the overall operational reliability and efficiency of the system. Therefore, having vanes or other flow-directing mechanisms on both sides of the impeller is crucial for optimal airflow management and compressor effectiveness.