Experimental investigations of heat transfer enhancement and flow losses in a channel with double rows of longitudinal vortex generators

Tiggelbeck, St.; Mitra, N. K.; Fiebig, M.

doi:10.1016/s0017-9310(05)80117-6

Cited by 122 publications

(40 citation statements)

References 1 publication

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“…However, the results from Ref. 7 showed that delta winglets produced better heat transfer performance than wings. No explanations were given on these contradictory results.…”

Section: Introductionmentioning

confidence: 98%

“…Extensive studies have been conducted on the heat transfer enhancement using turbulators in simulated heat exchangers, turbine blades and so on [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. The turbulator usually generates high turbulence vortical motion in uniform flows, which may change the mean velocity fields, modify the flow turbulence properties and the structures of the near wall layers in the velocity boundary layer.…”

Section: Introductionmentioning

confidence: 99%

“…They found that the longitudinal vortex effects on the Stanton number were attributed largely to the distortion in the mean velocity field. Fiebig and his group [5][6][7][8] conducted systematic experimental investigations on heat transfer enhancement and induced drag using delta wings, rectangular wings, delta winglets and rectangular winglets in channel uniform flows. They found that the heat transfer was increased up to 60-degree angle of attack.…”

Section: Introductionmentioning

confidence: 99%

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Flow structures and heat transfer characteristics in fan flows with and without delta-wing vortex generators

Chen

Shu

2004

Experimental Thermal and Fluid Science

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Effects of an external delta-wing vortex generator on the flow and heat transfer characteristics in fan flows and uniform flows were experimentally investigated and compared. A heated plate, installed on the bottom wall of a duct, was used as the heat transfer surface. Three-component mean and fluctuating velocity measurements were conducted using a laser Doppler velocimetry to characterize the flow structures and to obtain the near-wall flow parameters, including the axial mean velocity, axial vorticity and turbulent kinetic energy. Temperatures on the heat transfer surface were measured using thermocouples to obtain the Nusselt numbers. Results show that the external delta-wing vortex generator in fan flows has little overall effect on the near-wall averaged axial mean velocity and axial vorticity, but increases the turbulent kinetic energy, in the investigated X/D ranges. The increase in the turbulent kinetic energy by the delta-wing has little effect on heat transfer in the inherently vortical fan flows.Consequently, the delta-wing vortex generator in fan flows has little effect on the heat transfer augmentation.

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“…However, the results from Ref. 7 showed that delta winglets produced better heat transfer performance than wings. No explanations were given on these contradictory results.…”

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Flow structures and heat transfer characteristics in fan flows with and without delta-wing vortex generators

Chen

Shu

2004

Experimental Thermal and Fluid Science

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“…Tiggelbeck [4] experimentally studied the heat transfer enhancement and drag with double rows of delta winglets. The result showed that the critical angle of attack to create longitudinal vortices behind the second row was smaller than that behind the first one, and heat transfer coefficient and drag were increased by 80% and 160%.…”

Section: Introductionmentioning

confidence: 99%

Co-rotating equal strength vortex pair merging in channel flow with pressure gradient environment

Yi¹,

Liu²,

Hu³

2017

Proceedings of the 2017 6th International Conference on Energy and Environmental Protection (ICEEP 2017)

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Abstract. Experiments were conducted in order to understand the merging process of co-rotating equal strength vortex pair in channel flow with different pressure gradient environment. Cross-flow velocity measurements were performed at a series of downstream locations under zero, favorable and adverse pressure gradient conditions. The main finding is that the pressure gradient has a vastly effect on the merging process. As the merging environment changed from favorable pressure gradient (FPG) to adverse pressure gradient (APG), the increasing of the vortex spacing was observed in the first diffusive stage, which lead to a delayed convective stage. However, at the convective stage where the spacing of vortex pair center decreased, the decreasing process gradually speed up from FPG to APG accompanied with a faster vortices transportation and diffusion process so the merging process is accordingly accelerated. On the other hand, the vortex orientation difference was not as conspicuous as the vortex center separation distance.

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“…In fin and tube heat exchanger often negligible heat transfer takes place in the downstream of the circular tube due to a low velocity fluid which can be enhanced by several hundred percent by placing VG in the wake region behind the tubes (Biswas et al , 1994;Joardar and Jacobi , 2008). Several experimental and numerical studies on different configurations of VGs have been carried out over the last two decades (Turk and Junkhan , 1986;Joardar and Jacobi , 2008;Tiggelbeck et al , 1992Tiggelbeck et al , , 1993Jacobi and Shah , 1995;Jang et al , 2013) including fin and tube heat exchangers (Fiebig , 1995;. However, most of the studies are commonly based on convective heat transfer analysis.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of conjugate heat transfer and flow performance of a fin and tube heat exchanger with vortex generators

Singh

Sørensen

2017

Linköping Electronic Conference Proceedings

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Vortex generator is considered as an effective device for augmentation of the thermal-hydraulic performance of a heat exchanger. The aim of present study is to examine the influence of vortex generators on a double fin and tube heat exchanger performance. Vortex generator of rectangular winglet type is chosen and investigated at different angles of attack 0 • , −10 • and −20 • with the flow direction. Three-dimensional numerical model is developed and simulations are performed for a Reynolds number range 5000 ≤ Re ≤ 11000 taking conjugate heat transfer into account. The heat transfer and pressure loss characteristics are determined and analyzed for an in-line configuration of a fin and tube heat exchanger. In order to evaluate the enhancement in the performance on an equitable basis, the heat exchanger with plain fin surface is considered as a reference design. Results show that the angle of attack of a vortex generator has a significant impact on the volume goodness factor, and enhance the thermal performance of a fin and tube heat exchanger in comparison to the design with plain fin. The vortex generator at an angle of attack −10 • is found to perform superior over the Reynolds number range studied. At Re = 5000, the vortex generator with an angle of attack −10 • increases the volume goodness factor by 32% with respect to the baseline heat exchanger design.

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Experimental investigations of heat transfer enhancement and flow losses in a channel with double rows of longitudinal vortex generators

Cited by 122 publications

References 1 publication

Flow structures and heat transfer characteristics in fan flows with and without delta-wing vortex generators

Flow structures and heat transfer characteristics in fan flows with and without delta-wing vortex generators

Co-rotating equal strength vortex pair merging in channel flow with pressure gradient environment

Numerical investigation of conjugate heat transfer and flow performance of a fin and tube heat exchanger with vortex generators

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