PurposeThe main purpose of the paper is the validation of a broad range of RANS turbulence models, for the prediction of flow and heat transfer, for a broad range of boundary conditions and geometrical configurations, for this class of problems.Design/methodology/approachTwo‐ and three‐dimensional computations are performed using a general‐purpose CFD code based on a finite volume method and a pressure‐correction formulation. Special attention is paid to achieve a high numerical accuracy by applying second order discretization schemes and stringent convergence criteria, as well as performing sensitivity studies with respect to the grid resolution, computational domain size and boundary conditions. Results are assessed by comparing the predictions with the measurements available in the literature.FindingsA rather unsatisfactory performance of the Reynolds stress model is observed, in general, although the contrary has been expected in this rotating flow, exhibiting a predominantly non‐isotropic turbulence structure. The best overall agreement with the experiments is obtained by the k‐ω model, where the SST model is also observed to provide a quite good performance, which is close to that of the k‐ω model, for most of the investigated cases.Originality/valueTo date, computational investigation of turbulent jet impinging on to “rotating” disk has not received much attention. To the best of the authors' knowledge, a thorough numerical analysis of the generic problem comparable with present study has not yet been attempted.

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As an extension to the inviscid gas flow particle trajectory model presented in earlier papers, a complementary model has been developed to establish the effect of the blade boundary layer on the trajectories of particles and thus on the resulting erosion and/or deposition. The method consists essentially in tracing particles inside the boundary layer with initial conditions taken from the inviscid flow model. The flow data required for the particle trajectory calculations are obtained by using a compressible boundary layer flow computer program. This model has been applied to the first stage stator of a large electric utility gas turbine operating with coal gas. Results are compared with the predictions of the inviscid flow model. It is shown that the effect of the boundary layer on the trajectories of particles smaller than 6 μm is important. Since the hot gas cleaning system of a pressurized fluidized-bed gasifier system is projected to remove particles larger than 6 μm diameter effectively, it is concluded that an accurate assessment of turbine erosion and deposition requires inclusion of the boundary layer effect. Although these results emphasize the relative importance of the blade boundary layer, the absolute accuracy of the method remains to be demonstrated and is thought to be largely dependent on the basic data concerning the erosivity and sticking probability of particles.

This paper presents a computer package developed to calculate erosion damage in multistage turbines that operate with particle-laden gases. Erosion predictions based on calculated trajectories of particles are made either by using semiempirical erosion formula or through direct interpolation of existing experimental data. Also presented is an application of this package to a four-stage turbine that shows that the first and second stage rotor blades and the second stage stator blades may be subject to critical erosion damage.

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A Finite element computer code is presented for calculation of three-dimensional compressible flows in turbomachinery under the steady and potential flow limitations. The method used relies upon a variational statement equivalent to the classical velocity potential formulation of this problem. The solution domain is discretized by using hexahedral superelements each composed of six ten-node tetrahedral elements enabling quadratic interpolation of velocity potential. The code offers the flexibility of choosing a combination of subparametric and isoparametric elements. Applications of the code to the Gostelow cascade, an experimental turbine stator, the first stage stator and rotor of an electric utility axial flow turbine and finally to a mixed flow turbine rotor are presented. The validity of the results are established by comparison with the exact solution, experimental data and calculations by other numerical methods. Nomenclature c Blade chord c Axial blade chord Cp = (1 -V 2 ) Pressure coefficient for incompressible flow Ε Total number of elements % Unit vector in tangential direction [Κ] System property matrix Μ Element property matrix L ,/(TRTin) ,/2 Reference length M in =V in ,/(TRTin) ,/2 Reference Mach number on inlet plane [N] Interpolation function vector η Unit vector normal to surface Ρ = P/PinNondimensional pressure [Q] Global nodal values of absolute velocity potential [q] Element nodal values of absolute velocity potential R Gas constant [r] Element right-hand side vector r Radial coordinate S Surface τ = τ/Tin Nondimensional temperature [Τ]Transformation matrix