Vortex Combustor Research Articles

Effect of rear blunt body structure and inlet conditions on the flow and combustion characteristics of an advanced vortex combustor for a gas turbine

Effect of rear blunt body structure and inlet conditions on the flow and combustion characteristics of an advanced vortex combustor for a gas turbine

Effect of mainstream-forced-entrainment control strategy on the combustion performance of a cavity-based combustor

The trapped vortex combustor (TVC) displays potential for use in advanced aircraft engines because of its excellent combustion stability with a compact geometry. However, the existence of forced-entrainment phenomenon in the mainstream poses obstacles to the practical application of TVC. This study introduces passive control strategies using modified radial struts to address the issue of mainstream-forced-entrainment in a TVC. Additionally, experimental and numerical studies were conducted to investigate how the mainstream-forced-entrainment control strategy on the combustion performance of a TVC. The findings suggest that the inclined strut (case-2) and longer-vertical strut (case-3) are more effective than the short-vertical strut (case-1) in reducing mainstream entrainment into the cavity. This results in a larger vortex structure and a more concentrated fuel distribution within the cavity of case-2 and case-3, as compared to case-1. Consequently, case-2 and case-3 achieved much better ignition and lean blowout limit and combustion efficiency performances compared to case 1.

The Effect of Gas Distribution in a Straight-Flow Vortex Burner on the Combustion Process in a Limited Furnace Volume

The Effect of Gas Distribution in a Straight-Flow Vortex Burner on the Combustion Process in a Limited Furnace Volume

Composite combustion behaviors of tubular flame and central jet flame in a reduced-diameter vortex combustor

The characteristics of the tubular flame and the flow field mixing mechanism in a reduced-diameter vortex combustor are investigated by varying the fuel flow rate and equivalence ratio through experiments and numerical simulations. Single-layer tubular flame and double-layer composite tubular flame are found in the combustor under the coupling effect of the cyclone and the central jet. The composite tubular flame will be formed when the air in the combustor is more abundant (Ф>1.00), and the center flame frequency is linearly and positively correlated with the Reynolds number of the central jet air. When the Reynolds number exceeds 2000, the double-layer composite flame tends to stabilize, with the center flame frequency higher than 9 Hz. The turbulence of the central jet air promotes the mixing of reactants by enhancing the recirculation near the nozzle, guaranteeing the central flame's stable combustion. Through analysis of the burn rate of methane at the outlet and the emission species of CO and CO2, it is evident that the double-layer flame achieves the methane burn rate exceeding 95 %, while also exhibiting lower CO emissions compared to the single-layer flame.

Effects of fuel on the performance of miniature vortex combustion power system

Effects of fuel on the performance of miniature vortex combustion power system

Effects of Secondary Fuel Injectors Position and Angle on the Performance of a Miniature Trapped Vortex Combustor

ABSTRACT This paper investigates the impact of different positions and angles of secondary fuel injector on the flow field characteristics, fuel-air mixing, and combustion performance of a miniature trapped vortex combustor (TVC), utilizing a combination of experimental and numerical methods. The numerical computation results show a good agreement with experimental data. Detailed computational findings highlight the significant influence of varying injector positions and angles on miniature TVC performance. Adjusting the positions and angles of secondary fuel injectors lead to notable outcomes: Adjusting the positions and angles of secondary fuel injectors leads to notable outcomes: achieving a more stoichiometric mixture within the cavity, extending the region of intense combustion, and increasing combustion efficiency by up to 3.4%. These adjustments are conductive to enhancing the overall performance of a miniature trapped vortex combustor.

Structure Optimization of Hydrogen‐Fueled Multiple Direct‐Injection Trapped Vortex Combustor Using Response Surface Method

A hydrogen‐fueled multiple direct‐injection trapped vortex combustor is proposed to improve the unstable combustion and reduce NO emission. The effects of bluff‐body depth, bluff‐body height, and bluff‐body angle on the combustion flow characteristics are analyzed. NO emission is used as the main response value, the response surface method (RSM) is adopted to optimize the bluff‐body depth, bluff‐body height, and bluff‐body angle. The results show that the bluff‐body depth, bluff‐body height, and bluff‐body angle have significant effects on the NO emission, with the increase of the three parameters, NO emission first drops and then rises, but the effects on the pressure loss and outlet temperature distribution factor (OTDF) are very small. After optimization by RSM, the optimal bluff‐body parameters are the bluff‐body depth a = 56.5 mm, the bluff‐body height b = 128.9 mm, and the bluff‐body angle α = 77.6°. Under these circumstances, the maximum radial distances of the front concave vortex and the rear concave vortex reach 48 mm and 57 mm, respectively, which enhances the combustion stability. Furthermore, NO emission of 1.64 ppmv in the optimization structure is significantly optimized compared to NO emission of 4.32 ppmv in the original structure.

Performance optimization design of trapped vortex combustion chamber with a sand dune blunt body

In an effort to enhance the performance of the trapped vortex combustion chamber, this paper improved the trapped vortex combustion chamber and proposed a sand dune trapped vortex combustion chamber. Firstly, the effects of different inlet velocities and equivalence ratios on the performance of the two combustion chambers were analyzed. The results showed that under the same operating conditions, the performance of the sand dune trapped vortex combustion chamber was better than that of the trapped vortex combustion chamber. Then, a central composite design (CCD) response surface experimental method was adopted to optimize the structure of the sand dune trapped vortex combustion chamber in detail. The windward angle (α), leeward angle (θ), and rear blunt body height (h) were used as influencing factors. The combustion efficiency (η), pressure loss (δ*), and NOx emissions were used as response variables. Quadratic polynomial regression equations for η, δ*, and NOx emissions were established respectively. Subsequent to this, the expected value function method was employed for multi-objective optimization of the three regression equations. After optimization, compared with the original trapped vortex combustion chamber, the combustion efficiency of the sand dune trapped vortex combustion chamber increased from 87.56 % to 95.41 %, NOx emissions decreased from 747.94 ppm to 386.35 ppm, the outlet temperature distribution factor (OTDF) decreased from 0.21 to 0.07, and field synergy β diminished from 83.11 to 76.60. Although the pressure loss increased from 2.30 % to 3.50 %, this is within an acceptable range.

Analysis of vortex combustion flow in a chamber of guide ring coupling with swirl flow

To investigate the impact of different vortex structure on the combustion stability in a chamber, this paper evaluates the performance of a vortex combustion chamber coupled with a swirler and a guide ring. The simulated cases include different guide ring angles of 95°, 105°, 115°, 125° and 135°, in addition to a control case without coupling the guide ring. The distributions of velocity, vorticity, temperature, outlet temperature distribution factor ( OTDF), reaction rate, turbulent kinetic energy ( k), synergy angle ( β), and NO emission are numerically analyzed. Results show that the coupling of the swirler and guide ring changes the vortex structure and significantly influences the chamber performance. The increase of the guide ring angles ( α) enhances the interaction between the swirl flow and the direct jet, which intensifies heat and mass transfer, as well as turbulence. The application of the guide ring induces external entrainment of the jet, leading to the formation of a large central recirculation zone compared to that without a guide ring. With increasing the α from 95° to 135°, both average outlet velocity and tangential velocity ( Vt) at the coaxial line position decrease, while the flame length decreases by 286 mm. And the OTDF variation among all cases is less than 0.065. The β of the central section decreases from 76.18° to 70.17°. Furthermore, combustion chamber without the guide ring exhibits higher temperature and OTDF.

Numerical study of flame characteristics in a reduced-diameter vortex combustor

In this paper, the combustion process in a vortex combustor, which is composed of two volutes, a center nozzle, and a reduced-diameter cavity, is studied by CFD simulation. The combined effect of the center jet and cyclone vortex on the flame structure is revealed by analyzing the fuel transport mechanism and flow field characteristics. Results show that under different fuel and air supply conditions, two typical flame structures may form inside the combustor. When the equivalence ratio is 0.5 and the power is 40 kW and 50 kW, Flame A will be produced, which is mainly distributed near the center nozzle. Under other conditions, Flame B will be generated, which is a two-layer structure with an inner layer surrounding the center nozzle and an outer layer near the wall. The construction of Flame B inside the reduced diameter vortex combustor is mainly attributed to the strong cyclonic flow, which breaks the recirculation in the flow field, transporting the fuel to the near wall region and promoting secondary combustion. At this time, the methane burn rate can be as high as 99 %, which is 10 % higher than the methane burn rate of Flame A.

PROMISING TECHNOLOGIES FOR COMBUSTION OF USED OIL IN BURNERS

"Emissions of pollutants are of great public concern due to their impact on the environment and human health. There is an acute issue of saving energy resources while reducing harmful emissions during the combustion of various types of fuel. Used oil, which consists mainly of hydrocarbons, is an excellent alternative for partial or complete replacement of typical design fuels does not contain the heavy residual fraction characteristic of heavy fuels. This article provides an overview of alternative fuel combustion technologies. The review focuses on the principles of operation, key technologies in the field of used oil combustion. As an alternative to existing technologies on the market, an innovative design of a swirl burner for burning various types of fuel is presented in comparison with the closest analogue in terms of design and characteristics. The main advantages of using the innovative design of the burner are substantiated. The conducted literature review and analysis will be useful for further study of the efficient combustion of used oil. Keywords: combustion, vortex burner, fuel-air mixture, vortex, alternative fuel, used oil."

Experimental study on the combustion performance of a turboshaft engine annular combustor

Efficient application of trapped vortex combustion technology is a hotspot in the aerospace field. This paper describes a turboshaft engine combustor based on this technology, named as mixed-flow trapped vortex combustor (MTVC). MTVC utilizes stable vortex structure formed in cavity to promote combustion stability. RP-3 aviation kerosene required for combustion is directly injected into cavity, which continuously supplies energy to combustor. Combustion performance of MTVC with different inlet aerodynamic parameters and fuel-air parameters was studied experimentally on full-ring test rig, including combustion efficiency, pressure loss and outlet temperature profile. According to the experimental findings, MTVC has very high combustion efficiency under the testing conditions of this paper, all exceeding 96%. Pressure loss coefficient is positively correlated as the square of inlet Mach number. Pressure distribution of MTVC is largely consistent with inlet velocity. Outlet temperature profile is not a straight line at radial height, showing a distribution trend of high temperature in the middle of combustor outlet, and low temperature at both ends of combustor outlet. Peak temperature is essentially at 0.6 times combustor outlet height. There is a cyclical variation in circumferential direction. The variation between combustion efficiency and aerodynamic parameters is also obtained in this paper.

Combustion and emission performance of swirling-flow single trapped vortex combustor

The swirling-flow single trapped vortex combustor (SSTVC) provides a new design approach for aviation engine combustors, showing promising potential for achieving high-temperature rises or low emissions. However, current research on it is limited to demonstrating its feasibility and lacks further investigation into its combustion organization, combustion, and emission characteristics. In this study, experiments are conducted to investigate the flow field, combustion, and emission characteristics of the SSTVC under 5 inlet reference velocities and 3 inlet temperatures. As the inlet reference velocities increase from 9.96 m/s to 14.95 m/s, noticeable changes are observed in the backflow velocity of the cavity, increasing from 33.8 m/s to 48.3 m/s. By combining the flow field structure and flame features, the combustion organization of the SSTVC is summarized. With an increase in the inlet reference velocities, the combustion efficiency remains almost unchanged initially at 95.75% and then increases to 96.55%. The outlet temperature distribution improves, with the pattern factor value decreasing from 0.23 to 0.14. The carbon monoxide emissions initially increased from 94.91 to 99.89 and then decreased to 88.80, the total unburned hydrocarbons decreased from 23.22 to 16.03, and the nitrogen oxide emissions showed no significant change. With an increase in the inlet temperature, all parameters improved, with the combustion efficiency increasing from 93.71% to 96.61%, the pattern factor decreasing from 0.26 to 0.12, and all emission parameters decreasing as well.

The effect of toroidal geometrical shape on turbulent oscillations in a bidirectional vortex combustor

The paper reports on detailed studies of a bidirectional swirling flow structure in a toroidal vortex chamber under non-reactive and combustion conditions at the Reynolds numbers Re = 65,000 and Re = 10,000. The explanation of reduced velocity fluctuations near the head wall compared to simple cylindrical bidirectional chambers is also given. The studies were carried out using transient numerical simulations DES (Detached Eddy Simulation). The necessary experimental validation based on PIV (Particle Image Velocimetry) and temperature measurements were performed as well. The results show that fluctuations of all velocity components in the toroidal part of the chamber do not exceed 20% in non-reactive conditions and 10% in the combustion case. Additionally, temperature oscillations are less than 10% of the adiabatic stoichiometric temperature of propane-air mixture combustion. The studies of combustion at different equivalence ratios show that the rich combustion ϕ = 1.5 provides the most favorable conditions in terms of mixture ignition. Moreover, a large-scale backflow structure is formed beyond the outlet nozzle at rich modes that leads to an increase in combustion stability. This feature can be usefully applied in studies of mesoscale bidirectional arrays and developing multiport combustion chambers.

Experimental study on the influence of inlet velocity and fuel/air ratio on outlet temperature profile performance in a turboshaft engine combustor

This paper presents an experimental study on the influence of inlet velocity and fuel/air ratio (FAR) on the outlet temperature profile in a mixed-flow trapped vortex combustor (MTVC) working with RP-3 liquid fuel. This new MTVC is using a single cavity to stabilize flames for turboshaft engine. Temperature profile performances, such as temperature non-uniformity, radial temperature profile, profile factor (RTDF) and pattern factor (OTDF), were examined at atmospheric pressure on a fan-shaped test rig at different inlet velocities and fuel/air ratios. By analyzing the temperature pattern in the cavity, the reason for the characteristic law of the outlet temperature profile is obtained. The results indicate that the MTVC has achieved a satisfactory temperature profile, which can meet the requirements of the turbine. The radial temperature profile at combustor outlet is not a flat straight line, showing a pattern of high temperature in the middle of combustor outlet and low temperature at both ends of combustor outlet. The peak temperature is 0.6 times the height of combustor outlet. The high temperature zone with a constant FAR lean towards the top of the outlet center, and the temperature non-uniformity, OTDF and RTDF increase with increasing velocity. However, the high temperature zone approaches the outlet axis at a constant velocity as FAR changes. The temperature non-uniformity decreases with an increases of FAR. There is an optimal velocity where OTDF and RTDF pass through a minimum value. A decrease or increase in velocity beyond this optimal velocity results in an increase in both OTDF and RTDF. This mainly depends on the fuel distribution, the air jet mixing, the local FAR in cavity, and the location of high-temperature products in combustor outlet.

Experimental Investigation on Liner Cooling Characteristics of a Mixed-Flow Trapped Vortex Combustor

Experimental Investigation on Liner Cooling Characteristics of a Mixed-Flow Trapped Vortex Combustor

Large eddy simulation of combustion instability in a subcritical hydrogen peroxide/kerosene liquid rocket engine: Intermittency route to period-2 thermoacoustic instability

This paper presents the first numerical evidence of an intermittency route to period-2 thermoacoustic instability in a subcritical single-element liquid rocket engine burning hydrogen peroxide/kerosene as we decrease the equivalence ratio (ϕ) from fuel-rich to fuel-lean. To achieve this, three-dimensional compressible large eddy simulation algorithms combined with the Euler–Lagrangian framework are used. A one-equation eddy sub-grid turbulence model with a partially stirred reactor sub-grid combustion model is employed to simulate the spray turbulent combustion process in a high-pressure liquid-fueled combustor based on open-source platform OpenFOAM. This paper focuses on examining the transition process of the dynamical states in the thermoacoustic system and the synchronization between multiple subsystems. The results indicate that, as the equivalence ratio reduces continuously (1.5 ≤ ϕ ≤ 0.5), the system dynamics shift from period-1 oscillations (ϕ = 1.5) to period-2 oscillations (ϕ = 0.5) via intermittency (1.3 ≤ ϕ ≤ 0.9). Under the equivalence ratio of 0.7 (ϕ = 0.7), a transient mode switching between period-1 and period-2 was also observed. The synchronization processes between the pressure and combustion subsystems in terms of phase-locking and frequency-locking are responsible for the emergence of complex dynamical states. The cycle snapshots analysis also provides more details on the synchronization processes between the pressure and the multiple subsystems, such as vortex dynamics, mixture fraction, and combustion heat release. In summary, this paper sheds light on the complex non-linear thermoacoustic oscillations and the underlying physical mechanisms related to the two-phase flow of spray combustion in liquid rocket engines using three-dimensional large eddy simulations, paving the way for developing passive or active control methods.

Effects of the swirler on the performance of an advanced vortex combustor

Trapped vortex combustors have garnered significant interest due to the cavity vortex's insensitivity to flow disturbances. Swirling combustion is also highly desirable due to its excellent mixing performance. This study explores the potential of combining vortex combustors with swirling combustion under reacting conditions. Steady-state Reynolds-averaged Navier–Stokes equations are solved through three-dimensional numerical simulations. The results demonstrate a significant improvement in combustion efficiency, from 55% in original vortex combustor to over 99% in swirling vortex combustor, and fuel–air mixing effectiveness. The spatial spiraled vortex structure forms in the cavity and behind the blunt body when the swirler is used. The position of the blunt body influences the shape of the cavity vortex, with a round vortex structure forming when the cavity length to the total combustion chamber length ratio is around 0.2. When the radius of the blunt body to the radius of the combustion chamber, varying from 0.2 to 0.7, is 0.6, two main recirculation zones can be created in the model. Increasing the swirling number results in a larger recirculation zone in the cavity, with an elongated recirculation area appearing behind the blunt body at a blade installation angle of 60°, corresponding to the swirling number is 1.251. However, an excessively high swirling number leads to uneven pressure distribution in the outlet. These findings provide novel insights for advanced vortex combustor research and optimization.

Ignition process of a novel swirling-flow single trapped vortex combustor with RP-3 liquid aviation fuel

The ignition process of a novel combustion concept, named swirling-flow single trapped vortex combustor (SSTVC), is proposed in the present study. A high-speed camera was employed to record the ignition processes at the atmospheric pressure, inlet reference velocity of 4.5 – 9.9 m/s (Ma 0.011 – 0.022), and temperature of 423 K – 523 K. The segmentation method of the watershed transform is adopted to explore the flame area, flame height, and ignition delay time from the digital image. The results indicate that the ignition process can be divided into four phases, spark ignition, kernel generation, flame growth, and stable combustion. The three-dimensional flame propagation characteristics in the cavity and primary region are subsequently described. The inlet reference velocity and temperature rise will accelerate the flame propagation process, and the ignition delay times are reduced accordingly. The decreased flame area can be achieved by the increased inlet reference velocity or decreased temperature. Notably, the effect of inlet temperature becomes weaker after it exceeds 473 K.

Double chamber meso scale vortex combustor for micro scale electric generator based on thermo electric generator

Research on micro/meso combustor-based small-scale power plants is developing rapidly. This rapid development is motivated by a higher energy density than lithium-ion batteries. In addition, energy needs for portable and mobile devices also drive this development. Based on the opportunities and needs of these small-scale power plants, this study focuses on developing a double-chamber mesoscale vortex combustor. This research aims to compare the temperature profile and the electrical energy generated by single and multiple combustion chambers on the meso vortex combustor. The single chamber combustor has 56 × 28 × 10 mm, and the double combustor is 56 × 56 × 10 mm. Both meso vortex combustor has dimension with a 4 mm inlet diameter. In the meso scale vortex combustor, we also installed stainless steel wire mesh to compare the temperature with and without wire mesh. Based on the numerical study results, the flame can be stabilized in the double chamber combustor configuration. The wire mesh installation can enhance the flame stabilization process. Nevertheless, the wire mesh installation reduces the wall temperature because the mixture’s exit velocity is more stable than the combustor without the wire mesh. The result shows that a double chamber meso scale vortex combustor has a higher temperature and electric energy output than a single chamber combustor. The double chamber combustor can generate 9.5 Watt electric power with 12.6% energy conversion efficiency.