Vortical Structure of Reacting Flow in a Sudden-Expansion Combustor with Solid Fuel

2009 ◽  
Vol 25 (5) ◽  
pp. 1145-1148
Author(s):  
F. C. Hsiao ◽  
Y. H. Lai ◽  
J. T. Yang
Keyword(s):  
Solid Fuel ◽  
Vortical Structure ◽  
Sudden Expansion ◽  
Reacting Flow

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

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1784 ◽  
Author(s):  
Weixuan Li ◽  
Xiong Chen ◽  
Wenxiang Cai ◽  
Omer Musa
Keyword(s):  
Heat Transfer ◽  
Solid Fuel ◽  
Expansion Ratio ◽  
Swirl Flow ◽  
The Self ◽  
Sudden Expansion ◽  
Reacting Flow ◽  
Reattachment Point ◽  
Regression Rate ◽  
Ramjet Combustor

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.

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

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.

Experimental Study of Reaction and Vortex Breakdown in a Swirl-Stabilized Combustor

2009 ◽  
Author(s):  
Chukwueloka O. U. Umeh ◽  
Zvi Rusak ◽  
Ephraim J. Gutmark
Keyword(s):  
Vortex Breakdown ◽  
Test Chamber ◽  
Reacting Flows ◽  
The Other ◽  
Sudden Expansion ◽  
Reacting Flow ◽  
Fuel Injector ◽  
Dynamical Interaction ◽  
Other Hand ◽  
Flow Case

Non-reacting and lean reacting flow experiments are conducted in a swirl-stabilized combustor with several configurations of a Triple Annular Research Swirler (TARS) fuel injector. The test chamber is composed of the TARS swirler at the inlet of a straight cylindrical fuel pre-mixing section, followed by a sudden expansion and a finite-length concentric pipe. The combustor chamber exit is open to the atmosphere, hence pressure is ambient for all test cases. Non-reacting flow tests are conducted with air at 300K and 600K. The reacting flow tests use premixed air (preheated to 600K) and commercial grade gaseous propane fuel (injected at ambient temperature) at low equivalence ratios. Particle imaging velocimetry (PIV) is used to measure the distribution of axial, radial and circumferential velocity fields from which the swirl ratio at a cross section near the expansion plane and the position and size of the vortex breakdown zone are determined for a certain swirler configuration with non-reacting cold and pre-heated flows and with reacting flows at various equivalence ratios. Simultaneous OH chemiluminescence is taken and used to identify the location of the reaction zones and hence the flame anchoring point for each reacting-flow case. Results show the complex dynamical interaction between the flame and the breakdown zone, and the appearance of oscillations in the position of both. In the non-reacting cold flow case, the breakdown zone appears near the expansion plane. In the non-reacting pre-heated flow case on the other hand, it is pushed downstream of the dump plane. For reacting flows with low equivalence ratios (near the lean blow out point) the breakdown zone is anchored to the dump plane and expansion corners and is relatively stable, while the flame oscillates inside it. On the other hand, at higher equivalence ratios, the flame is anchored to the dump plane and expansion corners while the breakdown zone oscillates behind it. The swirl numbers measured near the expansion plane exhibits nice correlation with the position of the vortex breakdown and satisfies the necessary theoretical conditions for the first appearance of breakdown in a premixed reacting swirling flow.

Effect of Dome Geometry on Swirling Flow Field Characteristics of a Counter-Rotating Radial-Radial Swirler

2013 ◽  
Author(s):  
Yi-Huan Kao ◽  
Samir B. Tambe ◽  
San-Mou Jeng
Keyword(s):  
Flow Field ◽  
Flow Structure ◽  
Recirculation Zone ◽  
Swirling Flow ◽  
Aerodynamic Characteristics ◽  
Sudden Expansion ◽  
Reacting Flow ◽  
Clockwise Rotation ◽  
Expansion Angle ◽  
Flow Field Characteristics

An experimental study has been conducted to study the effect of the dome geometry on the aerodynamic characteristics of a non-reacting flow field. The flow was generated by a counter-rotating radial-radial swirler consisting of an inner, primary swirler generating counter-clockwise rotation and an outer, secondary swirler generating clockwise rotation. The dome geometry was modified by introducing dome expansion angles of 60° and 45° with respect to the swirler centerline, in addition to the baseline case of sudden expansion (90°). The flow downstream of the swirler is confined by a 50.8mm × 50.8mm × 304.8mm (2″ × 2″ × 12″) plexiglass chamber. A two-component laser doppler velocimetry (LDV) system was used to measure the velocities in the flow field. The dome geometry is seen to have a clear impact on mean swirling flow structure near the swirler exit rather than the downstream flow field. For the configurations with 60° and 45° expansion, no corner recirculation zone is observed and the swirling flow structure is asymmetric due to the non-axisymmetric dome geometry. The cross-section area of central recirculation zone is larger for dome geometry with 60° expansion angle, as compared to the 90° and 45° cases. The configurations with 60° and 45° expansion have higher magnitudes of negative velocity inside the core of central recirculation zone, as compared to the configuration with 90° expansion angle.

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

2002 ◽  
Vol 18 (1) ◽  
pp. 43-51 ◽  
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.

Controlling mechanisms of ignition of solid fuel in a sudden-expansion combustor

1995 ◽  
Vol 11 (3) ◽  
pp. 483-488 ◽  
Author(s):  
Jing-Tang Yang ◽  
Cliff Y. Y. Wu
Keyword(s):  
Solid Fuel ◽  
Sudden Expansion
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