Numerical Investigation of the Effect of Sudden Expansion Ratio of Solid Fuel Ramjet Combustor with Swirling Turbulent Reacting Flow

In this paper, the effect of sudden expansion ratio of solid fuel ramjet (SFRJ) combustor is numerically investigated with swirl flow. A computational fluid dynamics (CFD) code is written in FORTRAN to simulate the combustion and flow patterns in the combustion chamber. The connected-pipe facility is used to perform the experiment with swirl, and high-density Polyethylene (HDPE) is used as the solid fuel. The investigation is performed with different sudden expansion ratios, in which the port and inlet diameters are independently varied. The results indicated that the self-sustained combustion of the SFRJ occurs around the reattachment point at first, and then the heat released in reattachment point is used to achieve the self-sustained combustion in the redevelopment zone. The average regression rate is proportional to the sudden expansion ratio for the cases with a fixed port diameter, which is mainly dominated by the enhancement of heat transfer in backward-facing step. However, the average regression rate is inversely proportional to the sudden expansion ratio for the cases with fixed inlet diameter, which is influenced by the heat transfer mechanism of developed turbulent flow in the redevelopment zone.

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Numerical study on a new design of solid-fuel ramjet combustor with swirl flow

FES Journal of Engineering Sciences ◽

10.52981/fjes.v8i2.102 ◽

2019 ◽

Vol 8 (2) ◽

pp. 72-79

Author(s):

Omer Musa ◽

Chen Xiong ◽

Guoping Huang

Keyword(s):

Heat Transfer ◽

Parallel Computing ◽

Fluid Mechanics ◽

Chemical Kinetics ◽

Solid Fuel ◽

Numerical Study ◽

Swirl Flow ◽

Ramjet Combustor ◽

Afterburning Chamber ◽

Transfer Thermodynamics

A new design of solid-fuel ramjet is proposed and examined numerically in this paper. Multi-physics coupling code is developed using FORTRAN and parallel computing to solve the problems of multi-physics coupling of fluid mechanics, solid pyrolysis, heat transfer, thermodynamics, and chemical kinetics. Simulations are carried out for the proposed design then the results are compared with the classic design of the solid-fuel ramjet. It is found that the proposed design has improved the regression rate significantly; besides, the amount of released solid fuel is increased for the same size. A new flame has been observed inside the combustion chamber of the proposed design then the two flamed were emerged in the afterburning chamber.

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An Accurate Performance Prediction of Solid Fuel Ramjets Using Coupled Intake-Combustor-Nozzle Simulation

Journal of Mechanics ◽

10.1017/jmech.2020.46 ◽

2020 ◽

Vol 36 (6) ◽

pp. 933-941

Author(s):

A. M. Tahsini

Keyword(s):

Combustion Chamber ◽

Solid Fuel ◽

Solid Phase ◽

Three Dimensional ◽

Flow Fields ◽

Reacting Flow ◽

Computational Domain ◽

Regression Rate ◽

Fuel Flow ◽

Accurate Performance

ABSTRACTThe performance of the solid fuel ramjet is accurately predicted using full part simulation of this propulsion system, where the flow fields of the intake, combustion chamber, and the nozzle are numerically studied all together. The conjugate heat transfer is considered between the solid phase and the gas phase to directly compute the regression rate of the fuel. The finite volume solver of the compressible turbulent reacting flow is utilized to study the axisymmetric three dimensional flow fields, and two blocks are used to discretize the computational domain. It is shown that the combustion chamber's pressure is changed due to the fuel flow rate's increment which must be taken into account in predictions. The results demonstrate that omitting the pressure dependence of the regression rate and also the effect of the combustor's inlet profile on the regression rate, which specially exists when simulating the combustion chamber individually, under-predicts the solid fuel burning rate when the regression rate augmentation technique is applied to improve the performance of the solid fuel ramjets. It is also illustrated that using the inlet swirl to increase the regression rate of the solid fuel augments considerably the thrust level of the considered SFRJ, while the predictions without considering all parts of the ramjet is not accurate.

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DNS of Three-Dimensional Unsteady Separated Flow and Heat Transfer in a Sudden-Expansion Channel

Heat Transfer: Volume 3 ◽

10.1115/ht2005-72176 ◽

2005 ◽

Author(s):

Hiroyuki Yoshikawa ◽

Kimitake Ishikawa ◽

Terukazu Ota

Keyword(s):

Heat Transfer ◽

Rectangular Channel ◽

Three Dimensional ◽

Separated Flow ◽

Expansion Ratio ◽

Sudden Expansion ◽

Number Range ◽

Simulation Methodology ◽

Flow And Heat Transfer ◽

Unsteady Separated Flow

Numerical results of a three-dimensional unsteady separated flow and heat transfer in a sudden expansion rectangular channel are presented. A direct numerical simulation methodology was employed in the calculations using the finite difference method. Treated in the present study is a rectangular channel of aspect ratio AR = 4.0 and expansion ratio ER = 2.5 in a Reynolds number range from 200 to 1000. It is found that the flow becomes unsteady at Re = 400 and severely complicated at Re = 500 to 1000. The heat transfer characteristics are presented and discussed in relation to the flow ones.

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Augmented of turbulent heat transfer in an annular pipe with abrupt expansion

Thermal Science ◽

10.2298/tsci140816138t ◽

2016 ◽

Vol 20 (5) ◽

pp. 1621-1632 ◽

Cited By ~ 2

Author(s):

Hussein Togun ◽

Tuqa Abdulrazzaq ◽

Salim Kazi ◽

Ahmad Badarudin

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Reynolds Number ◽

Nusselt Number ◽

Surface Temperature ◽

Local Nusselt Number ◽

Expansion Ratio ◽

Sudden Expansion ◽

Inner Diameter ◽

Annular Pipe

This paper presents a study of heat transfer to turbulent air flow in the abrupt axisymmetric expansion of an annular pipe. The experimental investigations were performed in the Reynolds number range from 5000 to 30000, the heat flux varied from 1000 to 4000 W/m2, and the expansion ratio was maintained at D/d=1, 1.25, 1.67 and 2. The sudden expansion was created by changing the inner diameter of the entrance pipe to an annular passage. The outer diameter of the inner pipe and the inner diameter of the outer pipe are 2.5 and 10 cm, respectively, where both of the pipes are subjected to uniform heat flux. The distribution of the surface temperature of the test pipe and the local Nusselt number are presented in this investigation. Due to sudden expansion in the cross section of the annular pipe, a separation flow was created, which enhanced the heat transfer. The reduction of the surface temperature on the outer and inner pipes increased with the increase of the expansion ratio and the Reynolds number, and increased with the decrease of the heat flux to the annular pipe. The peak of the local Nusselt number was between 1.64 and 1.7 of the outer and inner pipes for Reynolds numbers varied from 5000 to 30000, and the increase of the local Nusselt number represented the augmentation of the heat transfer rate in the sudden expansion of the annular pipe. This research also showed a maximum heat transfer enhancement of 63-78% for the outer and inner pipes at an expansion ratio of D/d=2 at a Re=30000 and a heat flux of 4000W/m2.

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Flame Stability Analysis of Turbulent Non-Premixed Reacting Flow in a Simulated Solid-Fuel Ramjet Combustor

Journal of Mechanics ◽

10.1017/s172771910000201x ◽

2002 ◽

Vol 18 (1) ◽

pp. 43-51 ◽

Cited By ~ 4

Author(s):

Tong-Miin Liou ◽

Po-Wen Hwang ◽

Yi-Chen Li ◽

Chia-Yen Chan

Keyword(s):

Solid Fuel ◽

Large Scale ◽

Combustion Process ◽

Velocity Profiles ◽

Reacting Flows ◽

Reacting Flow ◽

Flame Stability ◽

Mean Velocity ◽

Ramjet Combustor ◽

High Reynolds

ABSTRACTTo investigate the flame stability in a solid-fuel ramjet combustor, time-accurate calculations using a compressible flow solver with a modified Godunov flux-splitting scheme have been performed on high Reynolds number turbulent non-premixed reacting flows over a backward-facing step with mass bleed on one wall. The combustion process considered was a one-step, irreversible, and finite rate chemical reaction. The numerical results for reacting flows show that the two-dimensional (2-D) simulations can provide reasonable predictions on the dimensionless particle number decay rate and residence time in the flame holding recirculation zone, evolutions of both axial and transverse mean velocity profiles, and critical characteristic exhaust velocity separating the sustained combustion from the non-sustained combustion. In addition to the validation of 2-D reacting flow calculations, two- and three-dimensionally computed mean-velocity profiles are compared with existing experimental data for isothermal flows to check the suitability of 2-D simulations on capturing the large-scale mean flows.

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

ASME 2015 Gas Turbine India Conference ◽

10.1115/gtindia2015-1206 ◽

2015 ◽

Cited By ~ 1

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.

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