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1

Optimization of heat transfer properties of nanofluid flow over a shrinking surface through mathematical modeling

Bhandari A., Pavan Kumar Pannala R. K.

International Journal of Applied Mechanics and Engineering

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2020

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Vol. 25, no. 2

40--56

EN

In the current study, a three dimensional incompressible magnetohydrodynamic (MHD) nanofluid flow over a shrinking surface with associated thermal buoyancy, thermal radiation, and heating absorption effects, as well as viscous dissipation have been investigated. The model has been represented in a set of partial differential equations and is transformed using suitable similarity transformations which are then solved by using the finite element method through COMSOL. The results for velocity and temperature profiles are provided for various values of the shrinking parameter, Biot’s number, heat generation/absorption parameter, thermal Grashof number, nanoparticle volume fraction, permeability parameter, magnetic parameter and radiation parameter.

2

Numerical simulation of 3D flow in VKI-Genoa turbine cascade including laminar-turbulent transition

Yerschov S., Derevyanko A., Yakovlev V., Gryzun M.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2016

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Vol. 20, No 1

43--61

EN

This study presents a numerical simulation of a 3D viscous flow in the VKI-Genoa cascade taking into account the laminar-turbulent transition. The numerical simulation is performed using the Reynolds-averaged Navier-Stokes equations and the two-equation k-ω SST turbulence model. The algebraic Production Term Modification model is used for modeling the laminar-turbulent transition. Computations of both fully turbulent and transitional flows are carried out. The Mach number contours, the turbulence kinetic energy, the entropy function as well as the limiting streamlines are presented. Our numerical results demonstrate the influence of the laminar-turbulent transition on the secondary flow pattern. The comparison between the present computational results and the existing experimental and numerical data shows that the proposed approach reflects sufficiently the physics of the laminar-turbulent transition in turbine cascades.

3

Experimental and computational studies of stall on a helicopter rotor airfoil

Surmacz K.

Journal of KONES

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2016

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Vol. 23, No. 3

511--517

EN

In the case of forward flight of a helicopter, the flow field around rotating blades of a rotor is highly threedimensional and very complex. Helicopter blades work across a wide range of angles of attack and airspeed. The stall occurs on the retreating blade in forward flight and causes dissymmetry of lift on a rotor disc. The investigation of the stall phenomenon has been performed using experimental and computational methods. Experimental analysis was made at the Ohio State University 6’’x 22’’ unsteady transonic wind tunnel. Research in the wind tunnel was performed using two methods: oil visualization (over a wide range of alpha and Ma) and pressure measurements. Computational part of the research has been done using Computational Fluid Dynamics tool. 2- and 3-dimensional calculations performed using ANSYS FLUENT software. In both experimental and computational cases, the 3D flow around a section of a rotor blade based on the SSC-A09 airfoil was analysed. The test article of the research was a section, which was located in the tip region of the main rotor blade of UH-60M Black Hawk helicopter. The research was conducted for a wide range of angles of attack and at several velocities. The most interesting part of the analysis concerned on unsteady flow conditions corresponding to stall.

4

Modernisation of the last stage in the low- pressure cylinder of a steam turbine using CFD and optimisation techniques

Rusanov A. V., Paschenko N. V., Yakovlev V. A., Yershov S. V.

Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka

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2008

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nr 133

291--298

EN

The results of gas dynamic improvement of the last stage in the low-pressure cylinder of a steam turbine are presented. The turbine stage performance and the 3D flow patterns were obtained with the CFD solver FlowER. Stage modernisation was carried out in two ways. First, stage blade sections were renovated, and then the 3D blade shape was optimised using the CFD and optimisation techniques. The optimised stage has stator blades with a compound lean at the hub and a compound sweep at the tip. The efficiency of the improved stage is higher by roughly 2 percent at nominal flow conditions and is up to 10 percent for low flow rate conditions as compared to that of the original stage.

5

CFD for turbomachinery applications – fifteen years experience with code FlowER

Yershov S. V.

Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka

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2008

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nr 133

369--382

EN

The paper presents shortly current state of numerical simulation of turbomachinery flows. The choice of flow model, turbulence modelling and numerical technique is considered by the example of CFD solver FlowER. The numerical results for turbomachinery flows concerning unsteady effects, flow leakages, film-cooling and blade shape optimization are shown.

6

A turbulence model for 3-d flows with anisotropic structure of turbulence

Czernuszenko W., Rylov A.

Archives of Hydro-Engineering and Environmental Mechanics

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2005

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Vol. 52, nr 4

303-320

EN

A new turbulence model for flows in open channels with compound cross-sections is presented. The structure of turbulence in these channels can be anisotropic. This structure is described by the turbulent stress tensor that is presented here as the sum of two tensors, namely, normal and shear stress tensors. The normal and shear turbulent stresses are expressed by the turbulence intensities and the mixing length tensor (MLT), respectively. The turbulence intensities can be learned from measurements or another suitable approaches. One such approach that allows calculating the main component of the normal stresses is presented in the paper. The components of MLT are defined based on a new concept of generic mixing length (GML). The generic mixing length is assumed to depend on both distances; from the nearest wall and from the water surface. To demonstrate how the new model works the basic hydrodynamic equations (parabolic approximation of Reynolds equations) together with the turbulence model are solved. The well-known Patankar and Spalding (1972) algorithm was used when solving these equations. A series of numerical simulations were performed for different components of MLT and different channel geometries.

7

Numerical simulation of 3D flow through a control valve

Badur J., Banaszkiewicz M., Karcz M., Winowiecki M.

Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka

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1999

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nr 115

31--36

EN

The paper deals with numerical calculations of 3D flow through a control valve. The presented calculations were performed using commercial code FLUENT/UNS. The results of numerical simulations were compared with experimental data.

8

Influence of non-uniform admission on the work of the first group of stages

Krzyślak P., Flaszyński P.

Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka

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1999

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nr 115

251--258

EN

The paper present results of the 3D flow calculations over a delivery channel domain of the turbine working with throttle governing. Based on the results, especially, the strong non-uniform mass flow rate distribution at the outlet plane of calculated channel, it was made an analysis of flow conditions and the mass flow distribution in blade passages of the first group of turbine stages.

9

Numerical simulation of 3D flow in axial turbomachines

Yershov S., Rusanov A. V., Gardzielewicz A., Lampart P., Świrdyczuk J.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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1998

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Vol. 2, No 2

319-347

EN

The paper is intended to describe a method for the calculation of 3D viscous compressible (subsonic or supersonic) flow in axial turbomachines described in the form of thin-layer Reynolds-averaged Navier-Stokes equations. The method draws on Godunov-type upwind differencing and ENO reconstruction suggested by Harten (1987), so as to assure monotonicity preservation and high accuracy of computational results. The computational efficiency is achieved thanks to the implementation of a simplified H-type multi-grid approach and delta -form implicit step. Turbulent effects are simulated with the help of a modified algebraic model of Baldwin-Lomax (1978). This method was at the foundation of a computer code-a complex software package to calculate 3D flow in multi-stage turbomachines that allows us to obtain local characteristics, like temperature, pressure, density or velocity distributions, as well as global characteristics, such as flow rates, stage reaction, flow efficiency for the considered turbine/compressor stage. The paper also gives selected results of computation of a number of turbomachinery cascades, showing that these results agree reasonably well with the available experimental data.