1. Introduction

Centrifugal compressors find usage over wide range of propulsion applications and are regarded as one among the key air-breathing propulsive engine components. The cognitive research and development of compressors is directed toward achieving a higher pressure ratio, higher

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© The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and eproduction in any medium, provided the original work is properly cited.

efficiency, and reduced structural weight of compressor and the engine as well. Various compressor stages achieve gradual increase in the stagnation-to-flow pressure contributed by flow diffusion. Energy is added in the rotor blade section, increasing the total pressure and absolute component of flow velocity. Stator blade row diffuses the flow, thus reducing absolute velocity component and elevating static pressure. Blade topology requires adaptation of a cautious design procedure to achieve the designated pressure rise while minimizing aero-thermodynamic losses in order to run and achieve design pressure ratios and design efficiencies.

The impeller design is the basic and major vital part of the design of the compressor. The

Numerical Simulations of a High-Resolution RANS-FVDM Scheme for the Design of a Gas Turbine Centrifugal…

1. At the inlet of the impeller, very high relative velocity of the shroud ð Þ Wsh,<sup>1</sup> should be avoided. 2. Separation of the flow in the passages of the impeller should be minimized so that the

4. The stability of the diffuser strongly depends on αc,<sup>2</sup> and for both vaneless and vaned

5. For the backswept impellers, the ratio of the relative velocities should be increased for

6. Little bit of the increase in the stagnation enthalpy will be attributed to that of the velocity, because of which the polytropic efficiency of impellers with nil back sweep will be less

7. Work coefficient for radial impellers with zero back sweep is around 0.9 and 0.5 for

8. To with stand the stress levels, the maximum rotational speed of the backswept impeller is

9. The above two conditions lead to decrease in the maximum possible work per stage for a

The specific work can be calculated using the following correlation, which is based on energy

In general for the design of the compressor, the inlet swirl is considered as zero and hence,

Cu,2,tl

8 >>><

>>>:

p0,<sup>2</sup> p0,<sup>1</sup>

¼ 1 �

! <sup>R</sup>

Cp � � <sup>1</sup> <sup>η</sup>p, <sup>c</sup> � �

ffiffiffiffiffiffiffiffiffiffiffi cosβ<sup>2</sup> p

� 1

9 >>>=

>>>;

<sup>Z</sup><sup>0</sup>:<sup>7</sup> (2)

10. Hence, if the maximum work per stage is not required, blade swept angles up to 50�

maintained less than that of the radial impeller with same tip diameter.

ðu2Cu, <sup>2</sup> � u1Cu, <sup>1</sup>Þ ¼ gcCpgT0, <sup>1</sup>

Cu,<sup>1</sup> ¼ 0. Furthermore, the Wiesner's correlation for slip factor is given by

<sup>σ</sup><sup>w</sup> <sup>¼</sup> slipfactor <sup>¼</sup> Cu,2, ac

. Further, it should be taken from 60 to 65�

WSh,<sup>1</sup> > 0:75.

99

can

(1)

for better design.

http://dx.doi.org/10.5772/intechopen.72098

following conditions for the design may be considered as limiting conditions

3. To meet the above limiting condition, the de Haller impeller ratio should be <sup>W</sup><sup>2</sup>

losses are minimized.

diffusers, αc,<sup>2</sup> ≤ 70�

betterment in the design.

backswept impellers.

backswept impellers.

and Euler turbine equations

be used.

2.2. Specific work

2.3. Slip factor

than that of backswept impellers.

In this chapter, a strong attempt is made to enumerate the detailed procedure of the centrifugal compressor in Section 2, concepts and basics of Numerical Schemes in Section 3. Further, a case study is discussed in detail in Section 4, the corresponding results and discussions are presented in Section 5. Final conclusions are summarized in Section 6.
