It will be assumed here that Pv(mean) is based on the simple calculation in conjunction with this factor. In most cases where equation 3.13 is used, the error due to the incorrect method of calculating pv (mean) is allowed for by an experimentally determined loss factor or coefficient for the form of velocity distribution it is hoped will be encountered. This mean that as the flow progresses from one stage to the next, the head increases approximately by the same amount, resulting in the multistage pump design having much higher pressure capabilities. Fan efficiency therefore depends on how much kinetic energy is produced, how low the impeller losses can be kept, and how well this kinetic energy is converted into potential energy (or static pressure) within the casing.Ĭonsidering the velocity triangles in Figure 3.1, the work done on the gas by the impeller will be the energy difference between exit and entry in the direction of rotation. The multiple impellers of a multistage centrifugal pump are all installed and rotated on the same shaft, and essentially act like separate pumps. The kinetic energy produced by the impeller is converted into pressure energy within the volute. Figure A. Considering the difficult requirements of good off-design operation performance in ship power application, single-stage centrifugal compressor with vaneless diffuser is adopted in the design of the main compressor of SCO2 recompression cycle. This force acting inside the pump is the same one that keeps water inside a bucket that is rotating at the end of a string. Preliminary design and impeller inlet design method. To fully understand therefore, Sections 1.5 and 1.6 in Chapterġ, dealing with fan characteristics, Chapter 5, Section 5.6 on system effect factors and Chapter 6 on flow regulation, some knowledge of the elementary theory is essential.įor the sake of simplicity the analysis which follows is not mathematically exact and further assumes that the air or gas is incompressible.Ī centrifugal fan receives air or gas at the impeller eye and delivers it to the casing volute at high velocity by imparting rotational energy. Because the impeller blades are curved, the fluid is pushed in a tangential and radial direction by the centrifugal force.