Effects of swirl on flow separation and performance of wide angle diffusers

Okhio, Cyril B.; Horton, Harry P.; Langer, Gregor

doi:10.1016/0142-727x(83)90039-5

Cited by 9 publications

(10 citation statements)

References 3 publications

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“…C.B Okhio et al [15] performed an experimental study to find the swirl strength that is required at the diffuser inlet in order to minimize losses in wide angle diffusers. Guohui Gan et al [16] presented a comparison between experimental measurements and Computational Fluid Dynamics predictions of the pressure loss coefficient of a wideangle diffuser.…”

Section: Previous Studies On Diffuser Performancementioning

confidence: 99%

A parametric study on the improvement of pressure recovery coefficient of a conical diffuser using Computational Fluid Dynamics

Ramji¹,

Tarun²,

Bharath³

et al. 2013

2013 International Conference on Energy Efficient Technologies for Sustainability

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The easiest and most practical way to make any system more environmentally friendly is to increase its energy efficiency. In a commercial gas turbine, this is done by attaching a diffuser at the turbine exit. The purpose of this study is to determine the combination of flow parameters and the diffuser design that would lead to the improvement of the pressure recovery coefficient of such a conical diffuser, and hence the overall efficiency of the turbo machine, like an industrial gas turbine, to which the diffuser is attached. The flow in a diffuser was simulated using Computational Fluid Dynamics (CFD) software (Star CCM+). The performance of the diffuser under different conditions was studied. The parameters under consideration were the half cone angle of the diffuser and the swirl number of flow. The study concluded that the highest pressure recovery coefficient, which corresponds to maximum efficiency, was obtained in the diffuser with a half cone angle of two degrees and swirl number 0.5.

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Section: Previous Studies On Diffuser Performancementioning

confidence: 99%

A parametric study on the improvement of pressure recovery coefficient of a conical diffuser using Computational Fluid Dynamics

Ramji¹,

Tarun²,

Bharath³

et al. 2013

2013 International Conference on Energy Efficient Technologies for Sustainability

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“…The results showed that the swirling inlet flow increases the performance of optimum diffuser compared to the uniform flow at the inlet. Senoo et al [7] and Okhio et al [8] suggest from their experimental study in a conical diffuser that the moderate swirl will delay the flow separation and increase the pressure recovery. Clausen et al [9] made detailed measurements of turbulence quantities for a 20° conical diffuser having swirl flow.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigations of flow through wide angle conical diffusers with uniform flow and swirl type velocity distortions at inlet

Hemalatha

Natarajan

2018

THERM SCI

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Swirl is a tangential velocity component of the fluid flow and is often present in the conical diffuser as a result of rotating machinery in the upstream section. The present experimental work is dedicated to study the effect of moderate swirl on wide angle conical diffuser performance and flow development. The experiments were performed in a low-speed open circuit wind tunnel. There are two different diffusers having a cone angle of 14° (with an area ratio 3.0) and 20° (with an area ratio 4.2) were selected for this investigation. The flow parameters have been measured using DANTEC DYNAMICS make constant temperature hot-wire anemometer (CTA). The results showed that the moderate swirl can significantly improve the stalled diffuser (20° cone angle) performance; however, it has a little effect on the diffuser (14° cone angle) having incipient turbulent boundary layer separation. It was confirmed that the introduction of moderate swirl reduces the chances of flow separation in wide angle conical diffusers.

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“…Sarpkaya (1974) performed experiments and studies on this theme in diverging tube geometries, which accounts for the infl uence of pressure gradient in the phenomenon. As of swirl addition to the fl ow for performance improvement in conical diff users, many experimental studies have been carried out, for example, Neve and Wirasinghe (1978), Senoo et al (1978), Okhio et al (1983) and McDonald et al (1971), in which they all mention the appearance of a central recirculating zone depending on the swirl intensity. Numerical studies have also been developed to predict swirling fl ows, such as the predictions of Cho and Fletcher (1989), Armfi eld et al (1990), Okhio et al (1986) and Pordal et al (1993).…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis of Swirl Effects on Conical Diffuser Flows

Dauricio

Andrade

2017

J.Aerosp. Technol. Manag.

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The present paper focuses on the effect of swirl on important parameters of conical diffusers flows such as static pressure evolution, recirculation zones and wall shear stress. Governing equations are solved using a software based on the finite volume method. Moreover, turbulence effects are taken into account employing the k-ε RNG model with an ennhaced wall treatment. The Reynolds number has been kept constant at 10 5 , and various diffuser geometries were simulated, maintaining a high area ratio of 7 and varying the total divergence angle (16°, 24°, 40°, and 60°). Results showed that the swirl velocity component develops into a Rankine-vortex type or a forced-vortex type. In the former, swirl is not effective to prevent boundary layer separation, and a tailpipe is recommended to allow a large-scale mixing to enhance the pressure recovery process. In the latter case, boundary layer separation is prevented but an intermediary recirculation zone appears. Higher pressure recovery is attained at the exit of the diffuser with swirl addition, without the need of a tailpipe. Results also suggest that there is exists an imposed swirl intensity where the energy losses are minimum thus leading pressure recovery to an optimum level.

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Effects of swirl on flow separation and performance of wide angle diffusers

Cited by 9 publications

References 3 publications

A parametric study on the improvement of pressure recovery coefficient of a conical diffuser using Computational Fluid Dynamics

A parametric study on the improvement of pressure recovery coefficient of a conical diffuser using Computational Fluid Dynamics

Experimental investigations of flow through wide angle conical diffusers with uniform flow and swirl type velocity distortions at inlet

Numerical Analysis of Swirl Effects on Conical Diffuser Flows

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