Book ChapterDOI

# Flow Control in T-Junction Using CFD Based Optimization

K. Srinivasan
01 Jan 2017-pp 687-696
TL;DR: In this article, the authors proposed a design methodology to achieve a desired single phase flow distribution in a T-junction by contouring the flow path of the duct using three bi-quadratic Bezier curves.
Abstract: The present work proposes a design methodology to achieve a desired single phase flow distribution in a T-junction. The desired flow control is achieved by contouring the flow path of the duct using three bi-quadratic Bezier curves. A Bezier curve is one of the parametric curves which is defined by a set of a few control points. These curves possess some interesting properties which render them as a good choice for the representation of smooth curves. A bi-quadratic Bezier curve is defined by five control points of which four are fixed in the present work (two control points to mark initial and final positions and another two points adjacent to them for tangent continuity). Different curves, which are nothing but the contours depicting the flow path, are obtained by moving the remaining one control point for each curve. Since in two-dimensional simulation, each control point is defined by two coordinates, in total, there are six optimization design variables for the three Bezier curves. The present work determines the optimal values of these design variables using CFD based optimization. The optimization is carried out using Box’s complex method with the objective function being the minimization of the percentage absolute error in the flow rate in the branch outlet. Constraint surfaces for the design variables are described such that the Bezier curves do not intersect each other. Numerical simulation of the geometry yields the value of objective function. The geometry creation and numerical simulation are performed in GAMBIT and FLUENT respectively in batch mode by integrating MATLAB, GAMBIT and FLUENT to enable automated optimization. Two dimensional numerical simulations were performed on a T-junction for three cases with branch outlet flow rates of 30, 50 and 70 % of the incoming flow rates. The optimal geometry for all the studied cases is determined within an flow rate error of 3 %.
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TL;DR: In this paper, the reliability and efficient design of full-scale automatic sprinkler systems for the fire protection of industrial facilities and process plants were considered, and specific routines were developed for the pump and sprinkler modelling, taking into account the phenomenon of choked flow when sonic velocity is reached at the outlet.
Abstract: The present study concerns the reliability and efficient design of full-scale automatic sprinkler systems for the fire protection of industrial facilities and process plants. In particular, sprinkler systems filled with pressurized air at idle state (dry pipe) were considered. In this prospect, Computational Fluid Dynamics (CFD) simulations were carried out in the framework of the OpenFOAM package to study the flow in the piping subsequently to the activation of one sprinkler head. A VOF (Volume of Fluids) approach was used to compute the air/water interface accounting for the compressibility of air (perfect gas), while turbulence was considered using the RANS-based k-e realizable model. In addition, specific routines were developed for the pump and sprinkler modelling, taking into account the phenomenon of choked flow when sonic velocity is reached at the outlet. The numerical results were first compared to measurements on a test bench of Gridded typology (scale 1 in volume) for the purpose of validation. Then, the influence of various parameters (i.e. initial pressure in the system, dimension of the outlet orifice) on the flow dynamics were assessed for sprinkler systems of Gridded and Tree typologies. In particular, the performance was evaluated in terms of time constant of the systems, i.e. the time necessary to reach steady-state water flow at the opened sprinkler head required to control a specific fire hazard.

4 citations

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Journal ArticleDOI
TL;DR: A new method for finding the maximum of a general non-linear function of several variables within a constrained region is described, and shown to be efficient compared with existing methods when the required optimum lies on one or more constraints.
Abstract: A new method for finding the maximum of a general non-linear function of several variables within a constrained region is described, and shown to be efficient compared with existing methods when the required optimum lies on one or more constraints. The efficacy of using effective constraints to eliminate variables is demonstrated, and a program to achieve this easily and automatically is described. Finally, the performance of the new method (the "Complex" method) with unconstrained problems, is compared with those of the Simplex method, from which it was evolved, and Rosenbrock's method.

1,285 citations

Journal ArticleDOI
TL;DR: In this article, the main existing models and solution methods were unified further to one theoretical framework, including Bernoulli theory and momentum theory, and discrete and continuum methodologies, and the generalised model was applicable to not only designs of continuum manifolds but also those of discrete manifolds with constant or varying factors.
Abstract: Flows in manifolds are of great importance in quite diverse fields of science and technology, including fuel cells, spargers, solar collectors, microchannels, porous infiltration and irrigation. Theory of flow distribution and pressure drop is vital to predict process performance and efficiency of manifold systems. In this paper, we examined research and development of theoretical models and methodology of solutions in flow in manifolds and highlight remarkable advances in the past fifty years. The main existing models and solution methods were unified further to one theoretical framework, including Bernoulli theory and momentum theory, and discrete and continuum methodologies. The generalised model was applicable to not only designs of continuum manifolds but also those of discrete manifolds with constant or varying factors. The procedure of design calculation is in reality straightforward without requirements of iteration, successive approximation and computer programme. The theoretical model provides easy-to-use design guidance to investigate the interactions among structures, operating conditions and manufacturing tolerance under a wide variety of combination of flow conditions and geometries through three general characteristic parameters (E, M and ζ) and to minimize the impact on manifold operability.

172 citations

22 Jun 1999
TL;DR: A survey of shape parameterization techniques for multidisciplinary optimization and highlights some emerging ideas on suitability criteria based on the efficiency, effectiveness, ease of implementation, and availability of analytical sensitivities for geometry and grids.
Abstract: This paper provides a survey of shape parameterization techniques for multidisciplinary optimization and highlights some emerging ideas. The survey focuses on the suitability of available techniques for complex configurations, with suitability criteria based on the efficiency, effectiveness, ease of implementation, and availability of analytical sensitivities for geometry and grids. The paper also contains a section of field grid regeneration, grid deformation, and sensitivity analysis techniques.

126 citations

Journal ArticleDOI
TL;DR: In this paper, a modelling approach for three-dimensional trajectories with particular application to hand reaching motions is described, where Bezier curves are defined by control points which have a convenient geometrical interpretation.
Abstract: Summary. A modelling approach for three-dimensional trajectories with particular application to hand reaching motions is described. Bezier curves are defined by control points which have a convenient geometrical interpretation. A fitting method for the control points to trajectory data is described. These fitted control points are then linked to covariates of interest by using a regression model. This allows the prediction of new trajectories and the ability to model the variability in trajectories. The methodology is illustrated with an application to hand trajectory modelling for ergonomics. Motion capture was used to collect a total of about 2000 hand trajectories performed by 20 subjects to a variety of targets. A simple model with strong predictive performance and interpretablility is developed.The use of hand trajectory models in the digital human models for virtual manufacturing applications is discussed.

52 citations

Journal ArticleDOI
TL;DR: In this paper, a water flow at the inlet and downstream, before the bifurcation, of a 90° tee pipe junction has been investigated, and the results showed that the RSM model performs the best in reproducing the experimental data.
Abstract: A water flow at the inlet and downstream, before the bifurcation, of a 90° tee pipe junction has been investigated. The tee junction bifurcates the flow of Reynolds number 1.26×105, based on the inlet bulk velocity and a pipe diameter of 50 mm, into a branch exit-to-inlet mass flow ratio Q1/Q3=0.5. Predictions and measurements of the streamwise component of velocity conducted with laser Doppler anemometry compared well in general. However, the fact that the flow bifurcates downstream to 90° causes the converged solution from three models for turbulence k–e, renormalization group theory (RNG) and Reynolds stress model (RSM) to differ from each other. At the inlet the second moment normalised with respect to both the outer and inner scales of velocity, ux and u ∗ , respectively, indicate non-symmetry, whereas the profiles of the streamwise component of velocity indicate symmetry. Downstream, close to the onset of flow bifurcation at the chamfer of the tee junction, the measured turbulence fluctuations damp down drastically within the inner and outer layers. The RSM model performs the best in reproducing the experimental data. Decay of turbulence has been observed also in U bends where measurements show typical behaviour of separation. In a separate paper the characteristics of the flow at the branch exit of the tee are analysed.

30 citations