scholarly journals A Numerical Investigation of the Performance of Linear Interpolation Schemes Coupled Finite Volume Method in the Analysis of Confined Convection-Diffusion Turbulent Flow Field

2021 ◽  
Vol 2 (6) ◽  
pp. 15-23
Author(s):  
Jane Gatwiri ◽  
Stephen Karanja ◽  
David Theuri
Keyword(s):  
Flow Field ◽  
Turbulent Flow ◽  
Finite Volume ◽  
Linear Interpolation ◽  
Experimental Results ◽  
Temperature Profiles ◽  
Interpolation Scheme ◽  
Governing Equations ◽  
Convection Diffusion ◽  
Turbulent Flow Field

Numerical solutions are never exact due to errors emanating from the scheme used in discretizing the governing equations and the flow domain. For convection-diffusion flow, the magnitude of these errors varies depending on the scheme used to interpolate the nodal values of the flow quantities to the interfaces. An interpolation scheme that minimizes these errors would give results that are consistent to experimental results. This paper documents the performance of three linear interpolation schemes; upwind differencing, central differencing scheme and the hybrid scheme in obtaining temperature profiles for a convection-diffusion turbulent flow field. To eliminate the enormous scales inherent in turbulent flow, the field variables present in the governing equations are decomposed into a mean and a fluctuating component and averaged. The closure problem was solved using the  turbulence model. The resulting equations are discretized using the robust finite volume discretization technique. The discretized equations are solved using a segregated pressure-based algorithm. The results revealed that the central difference interpolation scheme generate temperature profiles that were consistent with experimental results of Ampofo and Karayiannis, (2003).

scholarly journals Using finite volume method for investigating the turbulent flow field and heat transfer of a non-Newtonian nanofluid in a channel with triangular vortex generators

2021 ◽  
Author(s):  
Muhammad Ibrahim ◽  
Tareq Saeed
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Field ◽  
Turbulent Flow ◽  
Finite Volume Method ◽  
Finite Volume ◽  
Vortex Generator ◽  
Vortex Generators ◽  
Turbulent Flow Field ◽  
Volume Method

Abstract This study examines the turbulent flow field and heat transfer rate (HTR) of the non-Newtonian H2O-Al2O3-carboxymethyl (CMC) in a channel with vortex generators. The finite volume method and SIMPLE algorithm were employed for solving the partial differential equations. The mean Nusselt numbers (Num) and pressure drops were studied at angles of 30-60°, vortex generator depths of 1-3 mm, Reynolds numbers (Re) of 3000-30000, and nanoparticles volume fractions (φ) of 0.5% and 1.5%. According to the numerical results, the use of triangular vortex generators significantly incremented the Nusselt number (Nu) of the non-Newtonian nanofluid (NF), while it had a lower effect on the enhancement of pressure drop (DP). It was also indicated that a change in the vortex generator depth in the range of a few millimeters had no significant effects on the Nu and pressure drop. Moreover, a rise in the Re (i.e., more turbulent flow) significantly incremented HTR. An increase in the Re raised pressure drop; however, the Num incremented more than the pressure drop. Also, the variations of the local Nu indicated that the local Nu significantly incremented around vortex generators due to the formation of vortex flows. An enhancement in the volume fraction of the base fluid’s nanoparticles (NPs) from 0.5% to 1.5% significantly incremented HTR and the Nu.

Numerical simulations and analysis of the turbulent flow field in a practical gas turbine engine combustor

2021 ◽  
pp. 095765092110632
Author(s):  
Veeraraghava R Hasti ◽  
Prithwish Kundu ◽  
Sibendu Som ◽  
Jay P Gore
Keyword(s):  
Flow Field ◽  
Turbulent Flow ◽  
Numerical Simulations ◽  
Gas Turbine ◽  
Adaptive Mesh Refinement ◽  
Three Dimensional ◽  
Adaptive Mesh ◽  
Turbulent Structures ◽  
Cut Cell ◽  
Turbulent Flow Field

The turbulent flow field in a practical gas turbine combustor is very complex because of the interactions between various flows resulting from components like multiple types of swirlers, dilution holes, and liner effusion cooling holes. Numerical simulations of flows in such complex combustor configurations are challenging. The challenges result from (a) the complexities of the interfaces between multiple three-dimensional shear layers, (b) the need for proper treatment of a large number of tiny effusion holes with multiple angles, and (c) the requirements for fast turnaround times in support of engineering design optimization. Both the Reynolds averaged Navier–Stokes simulation (RANS) and the large eddy simulation (LES) for the practical combustor geometry are considered. An autonomous meshing using the cut-cell Cartesian method and adaptive mesh refinement (AMR) is demonstrated for the first time to simulate the flow in a practical combustor geometry. The numerical studies include a set of computations of flows under a prescribed pressure drop across the passage of interest and another set of computations with all passages open with a specified total flow rate at the plenum inlet and the pressure at the exit. For both sets, the results of the RANS and the LES flow computations agree with each other and with the corresponding measurements. The results from the high-resolution LES simulations are utilized to gain fundamental insights into the complex turbulent flow field by examining the profiles of the velocity, the vorticity, and the turbulent kinetic energy. The dynamics of the turbulent structures are well captured in the results of the LES simulations.

Turbulent flow-field effects in a hybrid CFD-CRN model for the prediction of NO and CO emissions in aero-engine combustors

Fuel ◽  
2018 ◽  
Vol 215 ◽  
pp. 853-864 ◽  
Author(s):  
A. Innocenti ◽  
A. Andreini ◽  
D. Bertini ◽  
B. Facchini ◽  
M. Motta
Keyword(s):  
Flow Field ◽  
Turbulent Flow ◽  
Field Effects ◽  
Aero Engine ◽  
Turbulent Flow Field

scholarly journals Extracting the turbulent flow-field from beam emission spectroscopy images using velocimetry

2018 ◽  
Vol 89 (10) ◽  
pp. 10E107 ◽  
Author(s):  
D. M. Kriete ◽  
G. R. McKee ◽  
R. J. Fonck ◽  
D. R. Smith ◽  
G. G. Whelan ◽  
...  
Keyword(s):  
Flow Field ◽  
Turbulent Flow ◽  
Emission Spectroscopy ◽  
Turbulent Flow Field

Experimental Investigation of Turbulence Structure in a Three-Nozzle Combustor

2007 ◽  
Author(s):  
Benjamin Boehm ◽  
Andreas Dreizler ◽  
Markus Gnirss ◽  
Cameron Tropea ◽  
Jens Findeisen ◽  
...  
Keyword(s):  
Flow Field ◽  
Turbulent Flow ◽  
Air Entrainment ◽  
Pollutant Emissions ◽  
Laser Doppler Velocimeter ◽  
Velocity Signal ◽  
Size And Shape ◽  
Recirculation Zones ◽  
Turbulent Flow Field ◽  
Secondary Air

Proper mixing of fuel, primary and secondary air is a major issue to optimize engine performance in terms of efficiency and pollutant emissions. The underlying turbulent flow field determines these mixing processes. Most experimental and numerical investigations are performed in single nozzle combustors for reasons of optical accessibility and simplicity. The focus of the present study is to compare the variation of the non-reacting turbulent flow field for the case of single-nozzle and three-nozzle operation. In addition, the influence of secondary air entrainment is investigated. The flow configuration is based on commercial geometries. Using a two component laser Doppler velocimeter (LDV) the mean and fluctuating velocities of all three components, as well as two Reynolds-stress components were measured. The autocorrelation function and spectral distributions of the fluctuating velocity signal clearly revealed coherent fluid motions. These observations, together with high speed-flow visualisations indicate a precessing vortex core (PVC). An additional lower frequency for all three nozzles in operation revealed a pulsation of the recirculation zones. A major result of this investigation is that the size and shape of the internal recirculation zones were significantly influenced by operation of adjacent nozzles. Furthermore the generation of PVCs were augmented in the three-nozzle configuration. The additional secondary air entrainment interacts with the primary flow, changing the size and shape of the recirculation zone and affecting the low frequency pulsation.

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