Improving Oxygenator Performance Using Computational Simulation and Flow Field-Based Parameters

During crystallization processes the control and effective distribution of heat transfer from the heat exchanger to the solution plays an important role. The turbulent flow field and the temperature variations in the solution determine the local supersaturation profiles and the spatial particle distribution. Thus they have a strong impact on the final product quality, production capacity and efficiency of the process. In this sense, a sensor able to determine in situ the local process variables to get better insight in the process behavior, would be required. The recently proposed Smart moving Process Environment Actuators and Sensors (Smart PEAS) is a promising initiative to achieve a more efficient process control. In this PEAS system a network of floating sensors is integrated using Ultra Wide Band (UWB) wireless technology to form a monitoring and control system. As a first phase in the development of the Smart PEAS, the research is focused on the accurate measurements of the flow field and local temperature distribution in a reactor. The hydrodynamics of the Smart PEAS are very important to achieve the necessary accurate process information. In order to determine the hydrodynamic characteristics of the Smart PEAS and to validate and compare the obtained results, laternative non intrusive techniques are used to investigate them in this work. Microencapsulated liquid crystals are used as a measurement technique to study the local temperature and flow field in a heat exchanger crystallizer geometry. To measure the 3D flow and temperature fields the microencapsulated liquid crystals are recorded in a sheet of light plane inside the crystallizer by two digital color cameras in a stereoscopic position. The images of the liquid crystals are correlated to obtain the three velocity components (3C), while from the colors of the microencapsulated liquid crystals the local temperature can be deduced after appropriate calibration. Parallel experiments are done to investigate the three dimensional trajectories of different sensor geometries in the equipment by direct visualization of the sensors. Computational fluid dynamics simulations are performed to calculate the flow field, temperature distribution and sensor trajectories. The results are compared with the experimental results for validation. The validation of the computational simulation results with the experiments gave the necessary confidence to predict flow fields in new crystallizer designs. On the basis of the analysis the Smart PEAS sensor design and the reliability of the measurements obtained can be compared and implemented.

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Influence of Core Swirling Motion on Aerodynamic Performances of Lobed Exhaust Nozzle

10.20944/preprints201911.0217.v1 ◽

2019 ◽

Author(s):

Yulin Ding ◽

Youhong Liu ◽

Liwei Du

Keyword(s):

Flow Field ◽

Cross Section ◽

Stokes Equations ◽

Model Simulation ◽

Computational Simulation ◽

Three Dimensional ◽

Mixing Efficiency ◽

Recovery Coefficient ◽

Thermal Mixing ◽

Aerodynamic Performances

Influence of core flow inlet swirl angle on aerodynamic performances of an exhaust nozzle with scarfed lobed mixer was studied by the validated computational approach. The computational simulation was conducted by resolving the steady form of discretized three-dimensional Reynolds Averaged Navier-Stokes equations with the shear stress transport k-Ω turbulence model. Simulation results depict that swirling motions have ignorable influence on the flow field of the top part in the cross sections slightly downstream of the lobed trailing edge. Besides, for the flow field downstream of the L/D=0.1 cross section, the swirling motions are suggested to cause the clockwise stream-wise vortex to stretch into several smaller-scale vortexes. When the case with a bigger swirling angle is investigated, the induced smaller-scale vortexes are more strengthened by the swirling motions. Concerning the 15° swirling case, the loss caused by the destroyed vortex pattern and the benefit induced by the improved smaller-scale vortexes almost counteract with each other with respect to the thermal mixing efficiency. In the last studied cross section as compared with the baseline case, the case with a maximum swirling angle of 30° has increased 6.94% for the thermal mixing efficiency and decreased 0.42% for the total pressure recovery coefficient.

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Unsteady Forced Convection in Packed Beds: Computational and Experimental Analysis

Heat Transfer, Volume 2 ◽

10.1115/imece2004-60715 ◽

2004 ◽

Author(s):

Ricardo Meji´a-Alvarez ◽

John R. Agudelo ◽

Ce´sar Nieto ◽

Laura C. Villa

Keyword(s):

Flow Field ◽

Forced Convection ◽

Computational Simulation ◽

Particle Diameter ◽

Packed Bed ◽

Heating Process ◽

Flow Profile ◽

Packed Beds ◽

Field Variation ◽

Unsteady Temperature

In this work, a process of unsteady forced convection in a packed bed of spheres was experimentally and computationally analyzed. A device was designed and constructed in order to run the experiments in packed beds. It was used to carry out an experimental run in a packing of ten aluminum spheres, which tube-to-particle diameter ratio was 2,4. Methane-air combustion products were kept flowing into the packed bed at constant inlet conditions, 2,8 m/s and 369°C. Packed spheres were heated from 25°C to gases temperature. While heating, temperature of spheres, tube wall and gases at different positions were measured to follow unsteady process. On the other hand, computational simulation was carried out by modeling the ten-spheres packing under the same flow conditions of the experimental run. Physical properties of gases were kept constant and fluid flow profile was solved before heating process. Results of unsteady temperature variation in different positions showed good agreement with the experimental measures. This result allowed inferring that flow field calculations were a satisfactory representation of the actual flow field, since temperature field variation depends strongly upon flow field. In conclusion, it was found that the Computational Fluid Dynamics (CFD) simulation is an accurate tool to analyze unsteady forced convection in packed beds. The device designed is a flexible and powerful tool to measure unsteady forced convection in packed beds. The behavior of the gas-to-solid heat transfer coefficient is a fundamental question to solve, and CFD supported on experimental measures is the way to solve it.

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Prediction of anode performances of direct methanol fuel cells with different flow-field design using computational simulation

Journal of Power Sources ◽

10.1016/j.jpowsour.2006.02.023 ◽

2006 ◽

Vol 157 (2) ◽

pp. 875-885 ◽

Cited By ~ 17

Author(s):

Min-soo Hyun ◽

Sang-Kyung Kim ◽

Doohwan Jung ◽

Byungrock Lee ◽

Donghyun Peck ◽

...

Keyword(s):

Fuel Cells ◽

Flow Field ◽

Direct Methanol Fuel Cells ◽

Computational Simulation ◽

Direct Methanol ◽

Methanol Fuel Cells ◽

Flow Field Design

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Computational Simulation of the Flow Field of a Filter System inside Self-Ventilated Road Tunnels due to Heavy Vehicle Traffic

The Aerodynamics of Heavy Vehicles II: Trucks, Buses, and Trains - Lecture Notes in Applied and Computational Mechanics ◽

10.1007/978-3-540-85070-0_38 ◽

2008 ◽

pp. 419-432

Author(s):

Florian Iser ◽

Raimund A. Almbauer

Keyword(s):

Flow Field ◽

Computational Simulation ◽

Heavy Vehicle ◽

Vehicle Traffic ◽

Filter System ◽

Road Tunnels

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Computational Simulation of an Altitude Adaptive Nozzle Concept

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.553.223 ◽

2014 ◽

Vol 553 ◽

pp. 223-228

Author(s):

K. Schomberg ◽

Graham Doig ◽

J. Olsen

Keyword(s):

Flow Field ◽

Computational Analysis ◽

Static Pressure ◽

Computational Simulation ◽

Analytical Techniques ◽

Nozzle Flow ◽

Viscous Effects ◽

Highly Sensitive ◽

Altitude Adaptive Nozzle ◽

Spatial Discretisation

A computational analysis of an annular converging-diverging (CD) and an altitude adaptive expansion-deflection (ED) nozzle is presented. Numerical results were generated using a 2D axisymmetric, pressure-coupled solver in conjunction with the Spalart-Allmaras turbulence closure model and second order spatial discretisation schemes. Results were recorded over a theoretical altitude range and compared to experimental static pressure readings and schlieren images. The correlation between numerical and experimental static pressure values was high for all cases. Comparison of schlieren imagery outlined the large variety of flow regions within the ED nozzle flow field. The interactions between these regions were highly sensitive to turbulence and reinforced that conventional inviscid analytical techniques are unable to accurately describe behaviour within the ED nozzle flow field. The results highlight the salient effect of viscous effects within the ED nozzle flow field and justify a continued approach utilising computational fluid dynamics to increase understanding of the ED nozzle concept.

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Multi-Scale Computational Simulation of Combustion Instability and Transition in a Model Afterburner

Volume 4A: Combustion, Fuels and Emissions ◽

10.1115/gt2017-63805 ◽

2017 ◽

Author(s):

Sriram Kalathoor ◽

S. R. Chakravarthy

Keyword(s):

Reynolds Number ◽

Flow Field ◽

Acoustic Field ◽

Stokes Equations ◽

Computational Simulation ◽

Combustion Instability ◽

Dominant Frequency ◽

Acoustic Mode ◽

Hydrodynamic Mode ◽

Transverse Acoustic

A multiple length and time scale approach is adopted to perform large eddy simulation (LES) of combustion instability in a model afterburner. In this framework, the full compressible Navier-Stokes equations are decomposed into incompressible flow to leading order and acoustic equations to first order. The basis for this decomposition is the disparity in the time and length scales of the flow and acoustic propagation respectively. The present framework yields a coupling between the flow field and acoustic field, in terms of the flow dilatation and acoustic Reynolds stress (ARS). Test cases for various Reynolds numbers (based on mass flow rates) are simulated within this framework, and used to study the dynamics of transition and instability in a model afterburner. As the Reynolds number is increased, the dominant frequency switches from being that of the acoustic mode to the hydrodynamic mode. When the excitation to the acoustic field from the combustion is switched off, a high frequency relating to the transverse acoustic mode of the combustor is observed to be excited in the flow field as an acoustic feedback to the flow. When the acoustic excitation is turned back on, the transverse acoustic mode excitation of the hydrodynamics continues to prevail, illustrating a hysteretic effect. The dominant excitation of hydrodynamic mode at high Reynolds number clearly shows a rapid mixing and shortened length of heat release rate zone, when compared to the case at low Reynolds number as well as when the flow and acoustic simulations are uncoupled.

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Computational Simulation of Axis Symmetric Aft Wall Angle Cavity in Supersonic Flow Field

AIAA Propulsion and Energy 2020 Forum ◽

10.2514/6.2020-3712 ◽

2020 ◽

Author(s):

Naresh Relangi ◽

Divyasri Garimella ◽

K Jayaraman ◽

Jayakumar Venkatesan ◽

S Jeyakumar ◽

...

Keyword(s):

Supersonic Flow ◽

Flow Field ◽

Computational Simulation ◽

Wall Angle

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