3.4. Finite volume discretization method(FVDM)

Any fluid flow problem can be solved with high resolution when the basic concept of continuum is considered during the numerical solution methodology. Finite volume discretization method (FVDM/FVM) is one such methodology developed by McDonald, MacCormack, and Paullay during 1970s. The basic structure of the FVM is as follows:

Preliminary design of the impeller and vaned diffuser is carried out by adapting a onedimensional model approach. Comprehensive design of the centrifugal compressor stage was

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

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

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Impeller was designed using guidelines from various sources and in specific from [6]. The number of impeller blade profiles was configured based upon a choice iterative method aiming for passage flow devoid of heavy separations, and it was streamlined and set at 19

Hub-to-tip ratio is a key owing to the secondary losses, which occurs in the flow regions near the end walls. The presence of any undesirable circulatory or cross-flows develops on account of rapid and steep flow turning through the blade channel accounting for annulus wall boundary layers. Therefore, impeller hub-to-tip ratio was set at 0.35 within the range of 0.3–

Mach number at impeller inlet was set at 0.65. Impeller inlet blade angles were setup by PCA Engineer's Vista CCD tool analytical calculations. The inducer leading edge angles are 35, 56, and 63, respectively, with incidences of 11.8, 3.7, and 0.1 at hub, mean, and shroud, respec-

Impeller backswept angle was set at 0 to minimize impeller diameter, and a lean angle of 30 was also incorporated into the design. Impeller exducer height at 13.7032 mm and impeller diameter of 257.954 mm were set by PCA Engineer's Vista CCD software impeller trailing

Data generated by Vista CCD tool were used to generate a 3D computer-aided design model of impeller. Inlet portion of 50 mm and horizontal was designed satisfying the diameter con-

In order to obtain higher pressure ratio in a radial diffuser, the diffusion process has to be achieved across a relatively shorter radial distance. This requires the application of vanes, which provide greater guidance to flow inside diffusing passages. The vaned diffuser was designed by observing various flow parameters reflected at impeller exit after performing

To circumvent flow separation, divergence of diffuser blade passages in vaned diffuser ring can be kept small by incorporating a large number of vanes. However, this can lead to higher friction losses. Thus, an optimum number of diffuser vanes must be employed and ensure flow passage divergence not to exceed 12. Thus, final diffuser design contains 30 blades. The

blade profiles. A rotational speed of 38,000 rpm was set for the impeller.

tively. Leading edge of the impeller was defined by an elliptic ratio of 6.

generated using ANSYS BladeGen module.

4.2. Impeller design

4.2.1. Impeller inlet

0.6 prescribed in [6].

4.2.2. Impeller outlet

straint of 280 mm.

4.3. Design of vaned diffuser

numerical simulations.

edge that was defined as a square cutoff.

