scholarly journals Evaluation of flow and heat transfer inside lean pre-mixed combustor systems under reacting flow conditions

2018 ◽  
Author(s):  
Srinath V Ekkad
Keyword(s):  
Heat Transfer ◽  
Reacting Flow ◽  
Flow Conditions ◽  
Flow And Heat Transfer

A Study on Flow Boiling in Microchannel With Piranha Pin Fin

2015 ◽  
Author(s):  
X. Yu ◽  
C. Woodcock ◽  
Y. Wang ◽  
J. Plawsky ◽  
Y. Peles
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Fluid Flow ◽  
Pressure Drop ◽  
Heat Transfer Performance ◽  
Flow Boiling ◽  
Transfer Performance ◽  
Flow Conditions ◽  
Pin Fin ◽  
Flow And Heat Transfer

In this paper we reported an advanced structure, the Piranha Pin Fin (PPF), for microchannel flow boiling. Fluid flow and heat transfer performance were evaluated in detail with HFE7000 as working fluid. Surface temperature, pressure drop, heat transfer coefficient and critical heat flux (CHF) were experimentally obtained and discussed. Furthermore, microchannels with different PPF geometrical configurations were investigated. At the same time, tests for different flow conditions were conducted and analyzed. It turned out that microchannel with PPF can realize high-heat flux dissipation with reasonable pressure drop. Both flow conditions and PPF configuration played important roles for both fluid flow and heat transfer performance. This study provided useful reference for further PPF design in microchannel for flow boiling.

Roughness Effects on Flow and Heat Transfer for Additively Manufactured Channels

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Curtis K. Stimpson ◽  
Jacob C. Snyder ◽  
Karen A. Thole ◽  
Dominic Mongillo
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Friction Factor ◽  
Flow Conditions ◽  
Roughness Effects ◽  
Flow And Heat Transfer ◽  
Technological Advances ◽  
Rectangular Channels ◽  
Significant Augmentation ◽  
Flow Through

Recent technological advances in the field of additive manufacturing (AM), particularly with direct metal laser sintering (DMLS), have increased the potential for building gas turbine components with AM. Using the DMLS for turbine components broadens the design space and allows for increasingly small and complex geometries to be fabricated with little increase in time or cost. Challenges arise when attempting to evaluate the advantages of the DMLS for specific applications, particularly because of how little is known regarding the effects of surface roughness. This paper presents pressure drop and heat transfer results of flow through small, as produced channels that have been manufactured using the DMLS in an effort to better understand roughness. Ten different coupons made with the DMLS all having multiple rectangular channels were evaluated in this study. Measurements were collected at various flow conditions and reduced to a friction factor and a Nusselt number. Results showed significant augmentation of these parameters compared to smooth channels, particularly with the friction factor for minichannels with small hydraulic diameters. However, augmentation of Nusselt number did not increase proportionally with the augmentation of the friction factor.

Effect of Downstream Contraction on Liner Heat Transfer in a Gas Turbine Combustor Swirl Flow

2015 ◽  
Author(s):  
Sandeep Kedukodi ◽  
Srinath Ekkad
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Swirl Flow ◽  
Reacting Flow ◽  
Flow Profile ◽  
Flow Conditions ◽  
Gas Turbine Combustor ◽  
Inlet Flow ◽  
Flow Simulations ◽  
Accelerated Flow

Established numerical approaches for performing detailed flow analysis happens to be an effective tool for industry based applied research. In the present study, computations are performed on multiple gas turbine combustor geometries for turbulent, non-reactive and reactive swirling flow conditions for an industrial swirler. The purpose of this study is to identify the location of peak convective heat transfer along the combustor liner under swirling inlet flow conditions and to investigate the influence of combustor geometry on the flow field. Instead of modeling the actual swirler along with the combustor, an inlet swirl flow profile is applied at the inlet boundary based on previous literature. Initially, the computed results are validated against available experimental data for an inlet Reynolds number flow of 50000 using a 2D axi-symmetric flow domain for non-reacting conditions. A constant heat flux on the liner is applied for the study. Two turbulence models (RNG k-ε and k-ω SST) are utilized for the analysis based on its capability to simulate swirling flows. It is found that both models predict the peak liner heat transfer location similar to experiments. However, k-ε RNG model predicts heat transfer magnitude much closer to the experimental values except displaying an additional peak whereas k-ω model predicts only one peak but tends to over-predict in magnitude. Since the overall characteristic liner heat transfer trend is captured well by the latter one, it is chosen for future computations. A 3D sector (30°) model results also show similar trends as 2D studies. Simulations are then extended to 3 different combustors (Case 1: full cylinder and Case 2 and 3: cylinders with downstream contractions having reduced exit areas) by adopting the same methodology for same inlet flow conditions. Non-reacting simulations predict that the peak heat transfer location is marginally reduced by the downstream contraction of the combustor. However the peak location shifts towards downstream due to the presence of accelerated flow. Reacting flow simulations are performed with Flamelet Generation Manifold (FGM) model for simulating premixed combustion for the same inlet flow conditions as above. It is observed that Case 3 predicts a threefold increase in the exit flow velocity in comparison to non-reacting flow simulations. The liner heat transfer predictions show that both geometries predict similar peak temperatures. However, only one fourth of the initial liner length experiences peak temperature for Case 1 whereas the latter continues to feel the peak till the end. This behavior of Case 3 can be attributed to rapid convection of high temperature products downstream due to the prevailing accelerated flow.

Three-Dimensional Analysis of Fluid Flow and Heat Transfer in Single- and Two-Layered Micro-Channel Heat Sinks

2008 ◽  
Author(s):  
M. L.-J. Levac ◽  
H. M. Soliman ◽  
S. J. Ormiston
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Numerical Study ◽  
Three Dimensional ◽  
Heat Sinks ◽  
Micro Channel ◽  
Flow Conditions ◽  
Flow And Heat Transfer ◽  
Computer Chips ◽  
Laminar Flow Conditions

Micro-channel heat sinks are currently at the forefront of cooling technologies for computer chips where the input heat flux is projected to exceed 100 W/cm2 [1, 2]. The quest for better heat-sink designs has produced different ideas, one of which is the idea of using multi-layered micro-channel heat sinks [3, 4]. The objectives of the present investigation were to conduct a detailed numerical study of the hydrodynamic and thermal behavior of a two-layered micro-channel heat sink and to compare the performance of the two-layered heat sink with that of a single-layered sink under laminar flow conditions.

A Comparative Study of Flow Boiling in a Microchannel With Piranha Pin Fins

2016 ◽  
Vol 138 (11) ◽  
Author(s):  
X. Yu ◽  
C. Woodcock ◽  
Y. Wang ◽  
J. Plawsky ◽  
Y. Peles
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Flow Boiling ◽  
High Heat ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Flow Conditions ◽  
Pressure Drops ◽  
Flow And Heat Transfer ◽  
Pin Fins

In this paper, we report on the recent development of an advanced microscale heat sink, termed as piranha pin fin (PPF). A 200 μm deep microchannel embedded with PPFs was fabricated and tested. Fluid flow and heat transfer performance were evaluated with HFE7000 as the working fluid. The surface temperature, pressure drop, heat transfer coefficient, and critical heat flux (CHF) conditions were experimentally obtained and discussed. A 676 W/cm2 CHF was achieved based on the heater area and at an inlet mass flux of 2460 kg/m2 s. Microchannels with different PPF configurations were investigated and studied for different flow conditions. It was found that a microchannel with PPFs can dissipate high heat fluxes with reasonable pressure drops. Flow conditions and PPF configuration played important roles for both fluid flow and heat transfer performances. These studies extended knowledge and provided useful reference for further PPF design in microchannel for flow boiling.

scholarly journals CFD SIMULATION OF VERTICAL SEVEN-ROD BUNDLE COOLED WITH SUPERCRITICAL FREON-12

2014 ◽  
Vol 3 (01) ◽  
pp. 17-28 ◽  
Author(s):  
X. Huang ◽  
K. Podila ◽  
Y.F. Rao
Keyword(s):  
Heat Transfer ◽  
Cfd Simulation ◽  
Turbulence Models ◽  
Flow Conditions ◽  
Transfer Coefficients ◽  
Cfd Simulations ◽  
Ansys Fluent ◽  
Heat Transfer Coefficients ◽  
Rod Bundle ◽  
Flow And Heat Transfer

In this paper, a seven-rod bare bundle was simulated using ANSYS Fluent 6.3.26 to accurately predict the fluid flow and heat transfer behaviour under supercritical flow conditions. Seven turbulence models were compared to identify the appropriate model to predict the experiments performed at the Institute of Physics and Power Engineering on a vertically oriented seven-rod bare bundle cooled with supercritical Freon-12. It was found that predictions of wall temperatures and heat transfer coefficients are sensitive to the choice of turbulence model as well as to the near-wall treatment. Overall, the CFD simulations were able to predict the measured sheath temperature profiles along the length of the bundle within reasonable accuracy.

Development of Test Rigs to Investigate Fluid Flow and Heat Transfer in a Stirling Engine Heater Head

2018 ◽  
Author(s):  
Pawan Kumar Yadav ◽  
Songgang Qiu ◽  
Koji Yanaga
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Test Section ◽  
Stirling Engine ◽  
Oscillating Flow ◽  
Flow Conditions ◽  
Test Rig ◽  
Charged Fluid ◽  
Preliminary Results ◽  
Flow And Heat Transfer

To study the fluid flow and heat transfer in a Stirling Engine Heater Head (HH), two benchtop test rigs were designed and manufactured. One is to evaluate flow loss in oscillating flow conditions and another is to evaluate heat transfer in unidirectional flow conditions. The main test section-heater head, is additively manufactured; the test section also consists of an additively manufactured regenerator and a heat rejecter. For fluid flow test rig, a linear actuator from Parker generates and maintains the oscillating flow by driving a piston in sinusoidal motion. The piston is sealed against the charged fluid using Trelleborg seals. At room temperature, by varying the charge pressure, frequency, and stroke length, multiple test conditions can be achieved. For heat transfer test rig, a Gast’s high-flow, low-pressure compressed air blower is used to deliver the flow. The data acquisition (DAQ) is comprised of National Instruments’ cDAQ and modules to measure the piston’s motion in real time, pressure with Kistler’s pressure transducers, and the temperatures with OMEGA’s thermocouples, located at both the inlet and outlet of the heater head. Presented also are the testing procedures, some expected results, and the Sage outputs that will be used to check against the measured data from the test rigs, including some preliminary results. Based on the preliminary results, pressure and position curves were sinusoidal, which is expected of oscillating motions, meaning the test rig is operating well.

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