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R. Mark Wilson - One of the best experts on this subject based on the ideXlab platform.

Ahmet Tandiroglu - One of the best experts on this subject based on the ideXlab platform.

  • Flow Geometry optimization of channels with baffles using neural network and second law of thermodynamics
    Computational Mechanics, 2008
    Co-Authors: Teoman Ayhan, B. Karlik, Ahmet Tandiroglu
    Abstract:

    Artificial Neural Networks results from an experimental study on the heat transfer and Flow characteristics in channels with baffles are presented. Nine different types of channels with baffles were used in order to test the effects of baffle spacing to and the influence of baffle geometries and their positions on heat transfer, and their Flow characteristics. Experiments were performed for laminar and turbulent Flows, and Prandtl number of 0.7. The convective heat transfer coefficients and pressure drops provided by the experimental studies and artificially generated data were examined. Finally, the geometric features of the proposed Flow Geometry to improve heat transfer can be selected in order to yield the maximum opposite reduction in heat exchange channel irreversibility by using entropy generation minimization method. The experimental results for different design constraints show that optimum baffle position angle for laminar Flow is 90° and for turbulent Flow is 45° and baffle spacing modulo length ratio is 3 for laminar Flow and two for turbulent Flow, respectively. Then, some new data is generated using artificial neural networks for succession parameters. Also these generated data are compared with experimental results. New Flow geometries are presented for the future applications.

  • Effect of Flow Geometry parameters on transient entropy generation for turbulent Flow in circular tube with baffle inserts
    Energy Conversion and Management, 2007
    Co-Authors: Ahmet Tandiroglu
    Abstract:

    Abstract The effect of Flow Geometry parameters on transient entropy generation for turbulent Flow in a circular tube with baffle inserts has been investigated. Different Flow Geometry parameters of pitch to diameter ratio ( H / D ), baffle orientation angle ( β ), ratio of smooth to baffled cross-section area ( S o / S a ) and ratio of tube length to baffle spacing ( L / H ) were varied parametrically during the experiments. One smooth tube and nine different baffle inserted tubes geometries were tested. The characteristic parameters of the baffled tubes are pitch to tube inlet diameter ratio H / D  = 1, 2 and 3; baffle orientation angle β  = 45°, 90° and 180°. The time averaged entropy generation corresponding to the Flow Geometry parameters were compared under the condition of constant heat flux. Air having a Prandtl number of 0.71 was used as working fluid, while stainless steel was considered as the pipe and baffle material. Nine empirical equations were derived to correlate the time averaged entropy generation as a function of the Reynolds number and the other experimental individual Flow Geometry parameters, pitch to diameter ratio, baffle orientation angle, ratio of smooth to baffled cross section area and ratio of tube length to baffle spacing. Finally, the general empirical correlation of the time averaged entropy generation was developed and considered to be applicable within the range of Reynolds number 3000 ⩽  Re  ⩽ 20,000 in the form of S gen ave ( t ) = 0.0054 Re - 0.793 Pr 0.4 ( H / D ) - 0.656 ( S o / S a ) - 14.006 β - 0.0264 ( L / H ) - 0.6051 .

  • Effect of Flow Geometry parameters on transient heat transfer for turbulent Flow in a circular tube with baffle inserts
    International Journal of Heat and Mass Transfer, 2006
    Co-Authors: Ahmet Tandiroglu
    Abstract:

    Abstract The effect of the Flow Geometry parameters on transient forced convection heat transfer for turbulent Flow in a circular tube with baffle inserts has been investigated. The characteristic parameters of the tubes are pitch to tube inlet diameter ratio H / D  = 1, 2 and 3, baffle orientation angle β  = 45°, 90° and 180°. Air, Prandtl number of which is 0.71, was used as working fluid, while stainless steel was considered as pipe and baffle material. During the experiments, different geometrical parameters such as the baffle spacing H and the baffle orientation angle β were varied. Totally, nine types of baffle inserted tube were used. The general empirical equations of time averaged Nusselt number and time averaged pressure drop were derived as a function of Reynolds number corresponding to the baffle Geometry parameters of pitch to diameter ratio H / D , baffle orientation angle β , ratio of smooth to baffled cross-section area S o / S a and ratio of tube length to baffle spacing L / H were derived for transient Flow conditions. The proposed empirical correlations were considered to be applicable within the range of Reynolds number 3000 ⩽  Re  ⩽ 20,000 for the case of constant heat flux.

Eric Feron - One of the best experts on this subject based on the ideXlab platform.

  • Stability of spatially distributed, intersecting aircraft Flows under sequential conflict resolution schemes
    Proceedings of the 2011 American Control Conference, 2011
    Co-Authors: Troy Hand, Eric Feron
    Abstract:

    This paper discusses the effect of sequential conflict resolution maneuvers of an infinite aircraft Flow through a finite control volume. Aircraft Flow models are utilized to simulate traffic Flows and determine stability. Pseudo-random Flow Geometry is considered to determine airspace stability in a more random airspace, where aircraft Flows are spread over a given positive width. The use of this aircraft Flow model generalizes the orthogonal Flow Geometry for arbitrary Flow width. A set of upper bounds on the maximal aircraft deviation during conflict resolution is derived. Also with this Flow Geometry it is proven that these bounds are not symmetric, unlike the symmetric bounds derived in previous papers for simpler Flow configurations (i.e. orthogonal Flow Geometry). Stability is preserved under sequential conflict resolution algorithms for all Flow geometries discussed in this paper.

  • Stability of Spatially Distributed, Intersecting Aircraft Flows Under Sequential Conflict Resolution Schemes
    arXiv: Optimization and Control, 2010
    Co-Authors: Troy Hand, Zhi-hong Mao, Eric Feron
    Abstract:

    This paper discusses the effect of sequential conflict resolution maneuvers of an infinite aircraft Flow through a finite control volume. Aircraft Flow models are utilized to simulate traffic Flows and determine stability. Pseudo-random Flow Geometry is considered to determine airspace stability in a more random airspace, where aircraft Flows are spread over a given positive width. The use of this aircraft Flow model generates a more realistic Flow Geometry. A set of upper bounds on the maximal aircraft deviation during conflict resolution is derived. Also with this Flow Geometry it is proven that these bounds are not symmetric, unlike the symmetric bounds derived in previous papers for simpler Flow configurations. Stability is preserved under sequential conflict resolution algorithms for all Flow geometries discussed in this paper.

Göran Lindbergh - One of the best experts on this subject based on the ideXlab platform.

  • Current distribution measurements in a PEFC with net Flow Geometry
    Journal of Applied Electrochemistry, 2004
    Co-Authors: Matti Noponen, Arne Lundblad, Jari Ihonen, Göran Lindbergh
    Abstract:

    A measurement system for current distribution mapping for a PEFC has been developed. The segmented anode is constructed so as to have high thermal conductivity in order to prevent the formation of large temperature gradients between the electrodes. The construction is therefore feasible for use at high current densities. Both segmented and unsegmented gas diffusion layers are used. The effect of inlet humidification and gas composition at the cathode side is studied. In addition, two different Flow geometries are studied. The results show that the measurement system is able to distinguish between current distribution originating from differences in proton conductivity, species concentration and gas diffusion layer properties.

Troy Hand - One of the best experts on this subject based on the ideXlab platform.

  • Stability of spatially distributed, intersecting aircraft Flows under sequential conflict resolution schemes
    Proceedings of the 2011 American Control Conference, 2011
    Co-Authors: Troy Hand, Eric Feron
    Abstract:

    This paper discusses the effect of sequential conflict resolution maneuvers of an infinite aircraft Flow through a finite control volume. Aircraft Flow models are utilized to simulate traffic Flows and determine stability. Pseudo-random Flow Geometry is considered to determine airspace stability in a more random airspace, where aircraft Flows are spread over a given positive width. The use of this aircraft Flow model generalizes the orthogonal Flow Geometry for arbitrary Flow width. A set of upper bounds on the maximal aircraft deviation during conflict resolution is derived. Also with this Flow Geometry it is proven that these bounds are not symmetric, unlike the symmetric bounds derived in previous papers for simpler Flow configurations (i.e. orthogonal Flow Geometry). Stability is preserved under sequential conflict resolution algorithms for all Flow geometries discussed in this paper.

  • Stability of Spatially Distributed, Intersecting Aircraft Flows Under Sequential Conflict Resolution Schemes
    arXiv: Optimization and Control, 2010
    Co-Authors: Troy Hand, Zhi-hong Mao, Eric Feron
    Abstract:

    This paper discusses the effect of sequential conflict resolution maneuvers of an infinite aircraft Flow through a finite control volume. Aircraft Flow models are utilized to simulate traffic Flows and determine stability. Pseudo-random Flow Geometry is considered to determine airspace stability in a more random airspace, where aircraft Flows are spread over a given positive width. The use of this aircraft Flow model generates a more realistic Flow Geometry. A set of upper bounds on the maximal aircraft deviation during conflict resolution is derived. Also with this Flow Geometry it is proven that these bounds are not symmetric, unlike the symmetric bounds derived in previous papers for simpler Flow configurations. Stability is preserved under sequential conflict resolution algorithms for all Flow geometries discussed in this paper.