Category: Axial Flow Air Compressors

An axial compressor is fitted with half-reaction blading, the blade inlet and outlet angles being 50° and 15° when measured from the axial direction. The mean diameter of a certain blade pair is 85 cm and the rotor runs at 5500 rpm. Calculate the necessary isentropic efficiency of the stage if the pressure ratio of…

The following losses occur in axial flow compressors:

Axial flow compressors have wide applications in the following: Note that the requirements of compressors for aircraft application:

The merits and demerits of axial flow compressors are given in Table 15.1.   Table 15.1 Merits and demerits of axial flow compressor over centrifugal compressor

The relationship between pressure rise and mass flow rate at various speeds is shown in Fig. 15.8. At a certain speed, efficiency increases as the mass flow rate increases and reaches a maximum value after which it decreases, as shown in Fig. 15.9. The power consumed increases as mass flow increases. Figure 15.10 shows the performance and constant efficiency…

The static pressure ratio from Eq. (15.15) is, Temperature rise in rotating blades, Pressure rise in rotating blades, Pressure rise in stationary blades is, Pressure increase in stage is, The stagnation pressure ratio is, If the work done per stage is assumed to be the same, then number of stage z is given by, If pressure ratio per stage…

Flow Coefficient: It is defined as the ratio of flow (or axial) velocity at inlet to the blade velocity. Mathematically, we can write Flow coefficient,  Now u = vf1 (tan α1 + tan β1) Also, vf1 = vf2 = vf Head or Work Coefficient: It is defined as the ratio of actual work done to the kinetic energy corresponding to the mean peripheral velocity. One can write Head or…

It is the isentropic efficiency of one stage of a multistage compressor. This small-stage efficiency is constant for all stages of a compressor with infinite number of stages. Consider the compression process of a multistage compressor on a T-s diagram as shown in Fig. 15.6 from total pressure p01 to p02 in four stages of equal pressure ratio with intermediate pressure p0a, p0b, and p0c. Overall…

Consider the incompressible isentropic and steady flow through a cascade from condition 1 to condition 2. Using Bernoulli’s equation, we have Now, v f1 = v f2 = v f