Volumetric velocity measurements (V3V) on turbulent swirling flows

Boushaki, Toufik; Koched, Amine; Mansouri, Zakaria; Lespinasse, Florian

doi:10.1016/j.flowmeasinst.2016.12.003

Cited by 25 publications

(9 citation statements)

References 37 publications

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“…The swirled configuration is derived from a laboratory LBC previously investigated experimentally and numerically. 1,31,32 The swirler delivers a swirl number of 1.1, which is higher than the previously investigated swirl number of 0.7 by Qureshi et al 18 and Salvadori et al 25 Through the combustion chamber, the swirl intensity attenuates till it reaches 0.5 of value at the NGV inlet. The dilution stream reaches the annular cavity that surrounds the combustion chamber and enters through the film cooling slots.…”

Section: Dhs Generatormentioning

confidence: 57%

Numerical prediction of heat transfer characteristics on a turbine nozzle guide vane under various combustor exit hot‐streaks

Mansouri¹

2021

Heat Trans

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The precise prediction of the aerothermal conditions at the outlet of modern combustors of aero engines is of primary interest in the aerothermal design of high‐pressure turbines. The use of high swirling flows to stabilize the flame in the new generation of lean‐burn combustors (LBCs) leads to shorter combustor length and high degrees of unsteady temperature. These aspects generate high levels of turbulence and complex temperature nonuniformity patterns at the combustor–turbine interface. Therefore, the nozzle guide vane (NGV) located at the interface exhibits a high inlet temperature gradient called a hot‐streak. The transport mechanism of the hot‐streak across the NGV needs to be decrypted to increase turbine service life and enhance its performance. In this context, the present study aims to examine numerically the effect of three new distorted hot‐streak gradients on the heat transfer characteristics across a turbine NGV. An innovative LBC is used to generate the three inlet hot‐streaks, which are highly swirled and distorted similar to real aero‐engine conditions. The use of such a generation approach avoids any simplification associated with uniform or circular contours that are widely used by researchers. A solid NGV cascade developed by NASA is adopted for the investigations. The results show significant differences in the thermal field on the cascade at each distorted thermal condition. The transport of the hot‐streak behaves differently under axial and swirl conditions. The presence of a swirl induces flow mixing and results in thermal load increasing on the cascade surfaces (NGV, hub, and shroud).

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Section: Dhs Generatormentioning

confidence: 57%

Numerical prediction of heat transfer characteristics on a turbine nozzle guide vane under various combustor exit hot‐streaks

Mansouri¹

2021

Heat Trans

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“…This empirical approach allows the estimation of all hydrodynamic force contributions from a single time series of three-dimensional flow fields, thus offering a relevant approach for problems requiring simultaneous shear stress and pressure determination, for example, on the surface of a fish body or fin whose boundary layer thickness is of similar order of magnitude as in the present case [108]. State of the art experimental approaches for volumetric measurements in 3D unsteady flows are constantly evolving with new developments in both hardware and processing algorithms [116,117,[152][153][154][155]. Future technical developments providing increased spatial resolution should allow a more precise estimate of the velocity spatial gradients inherent to the viscous shear stress calculation, while preserving a measurement volume large enough to prescribe proper boundary conditions for the pressure gradient integration approach.…”

Section: Plos Onementioning

confidence: 99%

Hydrodynamic stress maps on the surface of a flexible fin-like foil

Dagenais

Aegerter

2021

PLoS ONE

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We determine the time dependence of pressure and shear stress distributions on the surface of a pitching and deforming hydrofoil from measurements of the three dimensional flow field. Period-averaged stress maps are obtained both in the presence and absence of steady flow around the foil. The velocity vector field is determined via volumetric three-component particle tracking velocimetry and subsequently inserted into the Navier-Stokes equation to calculate the total hydrodynamic stress tensor. In addition, we also present a careful error analysis of such measurements, showing that local evaluations of stress distributions are possible. The consistency of the force time-dependence is verified using a control volume analysis. The flapping foil used in the experiments is designed to allow comparison with a small trapezoidal fish fin, in terms of the scaling laws that govern the oscillatory flow regime. As a complementary approach, unsteady Euler-Bernoulli beam theory is employed to derive instantaneous transversal force distributions on the flexible hydrofoil from its deflection and the results are compared to the spatial distributions of hydrodynamic stresses obtained from the fluid velocity field.

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“…In the near field at the burner exit, each jet is composed of two shear layers (ISL and OSL) owing to the annular geometry of the burner. More details about these works can be found in the previous paper of the authors [35][36][37].…”

Section: Swirl Effects On Flamesmentioning

confidence: 99%

Introductory Chapter: Swirling Flows and Flames

Boushaki¹

2019

Swirling Flows and Flames

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Swirling flows are used in a very wide range of industrial applications. In non-reacting cases, examples of applications include vortex amplifiers and reactors, heat exchangers, jet pumps, cyclone separators, whirlpools, tornadoes, etc. In reacting cases, swirlers are widely used in combustion systems, such as gas turbines, industrial furnaces, boilers, gasoline and diesel engines and many other practical heating devices. Effects of using swirl on flow and combustion are significant and various and concern, for example, aerodynamics, mixing, flame stability, intensity of combustion and pollutant emissions. In this chapter, we are interested in the use of swirling flows in combustion systems. In industrial plants, the geometric methods of flame stabilization are based on increasing the residence time of reactive gases either by the wake effect bluff-body burner, by the flow rotation of reactants swirl burner or by a combination of these two mechanisms. Burners with helical flows generally referred to as the swirl burner have very wide applications in the industrial field. In the literature, many examples of uses of swirling jets are found as a means of controlling combustion [1-4]. Other studies focused on the swirl effect on the characteristics of lifted flames [5], stabilization and blow-out phenomenon [6-8] and pollutant emissions [9-13]. 2. Swirl generation techniques There are several ways to generate the rotation of a flow. They can be classified into three main categories:

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Volumetric velocity measurements (V3V) on turbulent swirling flows

Cited by 25 publications

References 37 publications

Numerical prediction of heat transfer characteristics on a turbine nozzle guide vane under various combustor exit hot‐streaks

Numerical prediction of heat transfer characteristics on a turbine nozzle guide vane under various combustor exit hot‐streaks

Hydrodynamic stress maps on the surface of a flexible fin-like foil

Introductory Chapter: Swirling Flows and Flames

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