Swirl Vanes Research Articles

Experimental and Numerical Investigation of the Mixing Ratio for Various Vane Swirlers of the Combustion Chamber of a Gas Turbine Engine

The paper investigates the swirling flow behind the GTE combustion chamber swirler with blades installed under different angles. The mixing ratio in the flow is experimentally analyzed and compared with the estimated values obtained by a numerical approach and using various models of turbulent viscosity.

Experimental investigation of non-premixed and partially premixed methane lifted flames established on a lobed swirl injector

A lobed swirl injector was tested to examine its potential in combustion control for non-premixed and partially premixed flames. It was found in the experiment that the flame derived from the injector changed between attached and detached flames at different conditions, demonstrating a promising way to control combustion. When air is supplied through the external channel of the lobed swirl injector and fuel passes through the internal channel, a stable lifted flame that is partially premixed was established above the injector exit. With the increase of airflow rate, the flame lift-off height decreases gradually until it is reattached to the injector, forming a diffusion flame. When increasing the fuel flow rate, the lift-off height increases gradually until the flame is blown out. Flow fields of the partially premixed lifted flames were investigated using stereoscopic particle image velocimetry. Streamlines located in the near field of the injector exit do not expand but bend inward, which is quite different from the expansion motion at the exit of the traditional vane swirler. The trough structure on the lobed swirler leads to the outer air flowing inward. Although the crest structure should make the inside gas flow outward, the strong entrainment of the surrounding air would restrain the radial outward motion of the inner gas, thus causing a contracted motion. After the streamline develops to an axial position further away from the injector exit, the swirling jet begins to expand under effects of both the centrifugal force and the development of shear layer to form turbulence. This flow pattern affects both the flame stabilization position and the neighboring reaction zone structure significantly. The measurements also show that the lobed swirl injector is very capable of entraining the ambient air that is sucked into the mainstream from the downward direction.

Experimental investigation on gripper force of electrically activated non-contact swirl vane gripper

This research work evaluates, Suction Force, Stable levitation region, and clearance distance for evaluating the performance of the swirl vane gripper. The Swirl vane gripper is nothing but a new non-contact gripper that uses negative pressure created by the air swirling flow to create an upward-lifting force. The variation of the suggested parameters with motor speeds (1000 rpm to 20,000 rpm) was studied. From the F-h curve (i.e., suction force versus distance between the work piece and the gripper), stable levitation region of the gripper was obtained. Different clearance distances were set and the gripper was actuated at these clearance distances and the effect of clearance distance on maximum suction force was studied. It was found that the gripper can be used successfully to grip 2–4 in. silicon wafers. One of the main limitations, which was found to be in the gripper was that, vibration levels were high at an rpm of 18,000 and above. The variation of energy consumption of the developed gripper with lifting force was determined and electrical energy consumption (in Watts) versus lifting force was plotted. The experimental results were then compared with that of Bernoulli and Vortex gripper and the energy consumption was found to be 95.82% less for swirl vane gripper with the Bernoulli gripper and 92.24% less than that of vortex gripper.

Design and experimental evaluation of a plasma swirler with helical shaped actuators

In order to enhance the flow control effectiveness of the plasma swirl injector, dielectric barrier discharge (DBD) actuators with helical electrodes are developed and the performance is compared with that of straight actuators through flow field measurement. This new design can adjust the plasma distribution and increase the plasma intensity. More importantly, the design can be used to adjust the axial velocity besides the azimuthal velocity, therefore it can be used to mitigate flame blow-off or flashback. In addition, the plasma-induced flow can be aligned with the direction of flow moving out of the vane swirler accurately, which can reduce the pressure loss from the swirler. The helical shaped actuator is more suitable for working in conjunction with traditional mechanical swirlers, providing more flexibility in flow control. By changing the direction of the helical electrodes and their relative positions, four different plasma swirler configurations for flow control are considered, making flexible combinations with the vane swirler possible and providing more options for combustion control. Results of flow field measurement showed that a central recirculation zone (CRZ) appeared under the plasma actuation. Compared with that of the straight electrode actuation, the size of CRZ is increased and the back flow in CRZ is enhanced by the helical electrode actuation. Effect of CRZ on the azimuthal velocity dissipation is also observed.

Computational Fluid Dynamics Investigation of the Thermal Performances of a Swirler with Profiled Blades

Numerical simulations were carried out to investigate the swirling decaying flow generated by a novel axial guide vane swirler with profiled blades and no supporting device in a tube and its effect on heat transfer and pressure drop compared to a developed turbulent flow in a no swirl tube. Reynolds number ranged from 10,000 to 200,000. Turbulence was modeled using a Shear Stress Transport model and a Low-Reynolds approach. The swirling flow enhances significantly the heat transfer locally especially in the developing swirling flow region and globally with an increase of Nusselt number from 1.57 to 1.34 respectively for Reynolds number of 10,000 and 200,000. Pressure drop is also increased up to 2.9 for a Reynolds number of 200,000, however this is relatively low compared to other axial guide vane swirler device encountered in the literature. Furthermore, the Performance Evaluation Criterion of the swirling flow is higher than 1 for both Reynolds number of 10,000 and 30,000.

Central recirculation zone induced by the DBD plasma actuation

Central recirculation zone (CRZ) is commonly formed in the near field of the injector exit by the vane swirler and used to stabilize the flame. In our experiment, a CRZ induced by the DBD plasma actuation was observed in the low swirl burner configuration for the first time, which clearly demonstrated that the mechanism of the combustion control by the plasma swirler is mainly through the aerodynamic effect. Three dielectric barrier discharge (DBD) actuators are placed in a circular array around the axis to generate ionic wind in the circumferential direction of the injector. Characteristics of the flow field have been measured using Laser Doppler Anemometry. It is found that a central recirculation zone with the shape of an ellipsoid is formed in the non-reacting flow field with the plasma actuation. The position of the upstream stagnation point was determined by the strength of the actuation. Although the CRZ disappears in the reacting flow field as the result of combustion heat release, the influence of the discharge on the flame lift-off height is noticeable. The results demonstrate that swirl enhancement by the plasma swirler is feasible, flexible and effective as a non-intrusive measure for flow control.

Effects of swirler vane angle on palm biodiesel/natural gas combustion in swirl-stabilised gas turbine combustor

Combustion characteristics of palm biodiesel/methyl esters (PME) and natural gas (NG) blend were examined using a model gas turbine swirl burner at vane angle (θ) 30°, 45° and 60°. A twin fluid air blast atomiser was utilised for atomising liquid fuel at air-to-liquid ratio (ALR) 2.50. Swirling flow was initiated by using an axial swirler as main air passed through it. Combustible mixture was formed as swirling air flow mixed up with liquid fuel spray at burner outlet. Flame colour for PME/NG was mainly bluish, resembling that of neat PME despite subtle liftoff was observed in PME/NG swirl flames. Flame spectroscopic analysis showed that PME/NG swirl flames were more intense than baseline PME. Furthermore, θ = 60° operation led to significantly lower reaction intensity. Meanwhile, PME/NG combustion with 20%-30% NG input power fraction was observed to lower nitric oxide (NO) emission by a factor of 2.7 when compared with diesel and neat PME in θ = 60° combustion. Novel empirical models for emissions were also proposed, enabling the estimation of NO emission from PME/NG combustion at different NG input power proportions and vane angle. This research shows that PME/NG combustion is a promising way of reducing NO emission against neat PME and diesel in gas turbine operation. Moreover, flame instability provoked by liftoff in dual fuel operation is not aggravated, mainly due to nullification by intensified global reaction when NG is added. Such attributes feature PME/NG as a viable alternative fuel for use in land-based power generation gas turbines.

Performance enhancement of axial concurrent liquid\u2013liquid hydrocyclone separator through optimization of the swirler vane angle

Vane angle configuration is considerably affecting the internal flow behavior and separation performance of a concurrent axial inlet liquid–liquid hydrocyclone. This study was carried out to improve the design of the swirl generator by optimizing the vane’s deflection angle in an oil/water axial inlet hydrocyclone separator. Angles ranging from 37° to 75° were examined at various operational conditions, including mixture temperature, mixture flow rate, and water-to-oil ratio. Two analysis techniques have been coupled to achieve the aim. First, design of experiment by the response surface method was utilized to generate a combination of run/boundary conditions of swirler vane angles, inlet mixture temperatures, flow rates, and concentrations. The obtained 15 run/boundary conditions were adopted as cases for computational fluid dynamics simulation to determine the separation efficiency, tangential velocity and pressure drop of each case using ANSYS Fluent software. The optimization results show that the swirl generator with a 45° deflection angle generated slightly higher tangential velocity compared with higher and lower vane deflection angles. The separation efficiency obtained by using the 45° swirl generator was higher than other angles, in spite that the turbulence intensity is slightly higher at 45° compared to other vane angles.

Modeling gaseous non-reactive flow in a lean direct injection gas turbine combustor through an advanced mesh control strategy

Fuel efficiency improvement and harmful emissions reduction are the main motivations for the development of gas turbine combustors. Numerical computational fluid dynamics (CFD) simulations of these devices are usually computationally expensive since they imply a multi-scale problem. In this work, gaseous non-reactive unsteady Reynolds-Averaged Navier–Stokes and large eddy simulations of a gaseous-fueled radial-swirled lean direct injection combustor have been carried out through CONVERGE™ CFD code by solving the complete inlet flow path through the swirl vanes and the combustor. The geometry considered is the gaseous configuration of the CORIA lean direct injection combustor, for which detailed measurements are available. The emphasis of the work is placed on the demonstration of the CONVERGE™ applicability to the multi-scale gas turbine engines field and the determination of an optimal mesh strategy through several grid control tools (i.e., local refinement, adaptive mesh refinement) allowing the exploitation of its automatic mesh generation against traditional fixed mesh approaches. For this purpose, the normalized mean square error has been adopted to quantify the accuracy of turbulent numerical statistics regarding the agreement with the experimental database. Furthermore, the focus of the work is to study the behavior when coupling several large eddy simulation sub-grid scale models (i.e., Smagorinsky, Dynamic Smagorinsky, and Dynamic Structure) with the adaptive mesh refinement algorithm through the evaluation of its specific performances and predictive capabilities in resolving the spatial-temporal scales and the intrinsically unsteady flow structures generated within the combustor. This investigation on the main non-reacting swirling flow characteristics inside the combustor provides a suitable background for further studies on combustion instability mechanisms.

Recirculating structures and combustion characteristics in a reverse-jet swirl pulverized coal burner

Industrial pulverized coal boilers play an important role in the use of distributed energy, but still suffer from severe pollutant emissions, combustion instabilities and poor fuel adaptabilities. In this paper, numerical simulation and full-scale experiments were carried out to study the recirculating and combustion characteristics of a novel reverse-jet swirl pulverized coal burner with an adding bluff body and flexibly adjusted secondary air. The axial velocity stagnation contour and the out-of-plane vorticity contour were used to characterize the recirculation structure of reverse swirl flows. The original design achieves a moderate char burnout with the carbon content in fly ash to be 18.63% under a residence time of 0.158 s, which demands for the further improvements. However, if only the injection velocity of the secondary air is increased by halving the axial range of the swirl vane, the recirculating flow is strengthened to such an undesired degree that coal ignition appears in the primary air pipe, the burner-wall overheating and near-wall particle enrichment can occur. To overcome it, a bluff body was incorporated with the enhanced secondary air flow. The recirculation zone was restricted downstream the bluff body, thus eliminating possible early coal ignition. Besides, the width of the recirculating flow is broadened, resulting in a more stable combustion with a less fluctuated pressure signal at the furnace exit. The near-wall coal particle concentration is reduced by approximately 90%. As a result, the use of bluff body decreased the carbon content in fly ash to 8.55% by increasing the coal particle residence time to 0.171 s. In addition, the NO concentration at the burner outlet is decreased by 8% owing to a longer coal particle residence time in the reducing environment.

Experimental investigation of lean-dome high-airflow airblast pilot mixers' operability, emissions, and dynamics

In order to further improve operability and low-power combustion efficiency of single-venturi twin concentric swirlers Lean Direct Injection (LDI)-based lean dome combustion systems, the authors' previous work investigated the effect of outer swirler vane angle on LDI reacting flow characteristics. A typical single-element LDI injector comprises of a fuel atomization device (pressure injector or airblast), surrounded by high airflow twin swirlers with converging passages feeding a single venturi followed by a single diverging passage called flare. LDI injectors without flare can be classified as high airflow airblast or air-assist pressure atomizers, in contrast with conventional air atomizing devices where air-to-fuel ratio rarely exceeds 3 or 4. In the present investigation, the impact of the flare section on the reacting flow field and flame structure is systematically explored. Specifically, the lean blowout limits, flame shapes, reacting flow dynamics, and NOx emissions from swirl-venturi LDI and airblast injectors are experimentally characterized using a suite of optical diagnostics, including time-resolved particle image velocimetry, OH⁎/CH⁎/NO2⁎ chemiluminescence, and broadband flame imaging. Results reveal that the inclusion of a flare significantly increases the overall swirl strength of the injector. Conversely, by removing the flare, swirl strength is reduced, leading to flow pattern changes (such as a transition from recirculating to swirling jet flow), higher lean blowout limits, and higher peak oscillation frequency of the flow field, while NOx emissions decrease due to reduced characteristic residence times. Such results demonstrate an inherent design tradeoff between lowering NOx emissions and maintaining/enhancing operability for a single swirl injector.

Sound Pressure Level Analysis of a Liquid-Fueled Lean Premixed Swirl Burner with Various Quarls

Swirl burners are widely used in numerous practical applications since they are characterized by low pollutant emission and a wide operating range. Besides reliable operation, a burner must fulfill noise emission regulations, which is often a sound pressure level in dB(A) when people are affected. Therefore, the present paper evaluates the overall sound pressure level (OASPL) variation of a 15-kW liquid-fueled turbulent atmospheric swirl burner at various setups. Firstly, the combustion air flow rate was adjusted, which induced a swirl number modification due to the fixed swirl vanes. Secondly, the atomizing pressure of the plain-jet airblast atomizer was modified, which also affected the swirl number. High atomizing air jets notably increased combustion noise by intensifying the shear layer. Thirdly, a geometrical modification was performed; 0°–60° half cone angle quarls in 15° steps were installed on the lip of the baseline burner for extended flame stability. By filtering the OASPL to the V-shaped flames, a linearly decreasing trend was observed as a function of swirl number. Their derivative also has a linearly decreasing characteristic as a function of the atomizing pressure.

Effect of velocity and pressure on performance of a full-scale SG steam separator package

Steam separator package including swirl-vane separator, gravity and dryer is crucial for supplying the qualified steam for the turbines in nuclear steam generator (SG). In this paper, steam-water experiments are carried out to study the separation efficiency, moisture carryover (MCO) and pressure loss of a full-scale SG steam separator package of the GEN-III advanced PWR. The system pressure ranges from 2 to 6 MPa and the superficial velocities of the steam jg and water jl are 1.47–5.91 m/s and 0.18–1.05 m/s, respectively. At rated pressure of 6 MPa, the results indicate that the separation efficiency of swirl-vane separator is insensitive to jg at low jl but decreases with jg at high jl. Generally, a larger jl causes a higher efficiency. Nevertheless, both the influence of jg and jl on the separation efficiency of gravity and dryer is minor. The MCO of swirl-vane separator and gravity decreases with jg increasing or jl decreasing whereas the residual wetness at dryer exit exhibits minor change with jg and jl. The pressure loss of swirl-vane separator increases with both jg and jl increasing while it increases gradually with jg but shows slight change with jl in the dryer. Overall, a higher pressure leads to a lower separation efficiency of swirl-vane separator and gravity but a higher dryer efficiency, a lower MCO and a higher-pressure loss of the whole separator package. Considering the effect of velocity and pressure, empirical correlations are proposed to predict the performance of swirl vanes, which are the key components for the separation performance and pressure loss.

Experimental study on the separation performance of a full-scale SG steam-water separator

Steam separator package including swirl vane separator, gravity and dryer is crucial for guaranteeing steam humidity below 0.1% in SG. In this paper, a high-pressure flow system is designed to study the performance of a full-scale steam separator package at a rated pressure of 6 MPa and temperature of 275.6 °C. To obtain separation efficiency, moisture carryover and pressure drop of each stage, the Reynolds number steam and water are 1 × 106–6 × 106 and 8.27 × 105–3.2 × 106, corresponding to 25–145% load. Results indicate that the separation efficiency ranges from 97 to 99%, 0.5 to 2% and 0.2 to 0.75% for separator, gravity and dryer. The moisture carryover ranges from 2 to 16% and 1 to 4% for separator and gravity, and is below 0.1% at dryer outlet. The pressure drop ranges from 2 to 24 kPa and 0.3 to 3 kPa for separator and dryer. Empirical correlations for swirl vanes are proposed, which are responsible for more than 85% and 70% of total separation efficiency and pressure drop.

Development and Efficiency Testing of Sucker Rod Pump Downhole Desanders

Summary Tense economic situations push the demand for low-cost oil production, which is especially challenging for production in mature oil fields. Therefore, an increase in the meantime between failure and the limitation of equipment damage is essential. A significant number of wells in mature fields are suffering under sand by-production. The objective of this paper is to show the development process and the testing procedure of an in-house-built, effective downhole desander for sucker rod pumps on the basis of a sophisticated analytical design model. In weak reservoir zones, often the strategy to prevent equipment damage due to sand by-production is the sand exclusion method using a gravel pack. Nevertheless, a certain amount of small sand grains still enter the wellbore and may damage the sucker rod pumping system over time. In early 2018, various types and sizes of downhole desander configurations were tested at the pump testing facility (PTF) at the University of Leoben (Montanuniversitaet Leoben). In a period of about 4 months, testing took place under near field conditions to find the optimum and most efficient design. The design optimization was focused on the geometry of the swirl vanes and the sand separation distance at the sucker rod pump intake. An analytical model provided the basis for geometric optimization. Concurrently, field tests of the in-house downhole desander were performed in the Vienna Basin that confirmed the findings of the tests at the PTF. The test results have shown that the downhole desander design and the pumping speed are the most influencing parameters on sand separation efficiency. Poor design in combination with a wrongly selected pumping speed can reduce the sand separation efficiency to lower than 50%, while if all parameters are chosen correctly, the sand separation efficiency can be 95% or higher. The grain size distribution is the additional parameter that enables a decision and ranks the performance. The sensitivity analysis, performed for several downhole desander types, has shown the high dependency of the sand separation efficiency on the major desander design parameters. Proper selection of the components and operating parameters will contribute to an increase in the meantime between failures. This paper will present the testing configurations, the development of the high-efficiency in-house downhole desander, and the sensitivity analysis performed on the design.

Effect of swirl vanes angle on erosion behaviour of AISI 316 pipe bend

Erosion wear is one of the major problems in thermal power plant components involving coal ash transportation viz., pipe line, pipe bends, valves, slurry pumps casing and impeller due to high velocity ash slurry flows, which reduces the life of the components and increases the expenditure incurred of the plant. In the current study the effect of induced swirl on erosion wear due to different swirl vanes of inclination angles 7.5°, 11.25°, 15° and 30° has been investigated at a pipe bend. The erosion wear on a pipe bend without a swirl vane for particle size of 150 µm has been calculated for velocities of 10 m/s, 20 m/s and 30 m/s with erodent flow rates of 0.2 kg/s and 0.3 kg/s and compared against erosion rates when a swirl vane is placed upstream of the bend. The optimal distance of placing the vane has been found out by placing the vanes at a distance of 280 mm, 320 mm and 360 mm from inlet of the pipe. It is found that erosion wear decreases for all of the cases except when a 30° vane was introduced for a flow velocity of 30 m/s and 7.5° vane when placed at a distance of 360 mm from the inlet, is found to be the most effective for erosion reduction.

Computational grid impact on numerical computing results of three-dimension non-stationary swirl flow behind the vane swirler

Computational grid impact on numerical computing results of three-dimension non-stationary swirl flow behind the vane swirler

Characteristics of contactless swirl vane gripper by investigating the negative pressure and clearance

In this paper the characteristics of contactless swirl vane gripper and effect of negative pressure is discussed. The ultimate work of contactless gripper is to lift the light weight components without making contact by means of negative pressure created by the vanes. The vane’s model is modified and comparison of performance measurements is made for changed design and existing design. The contactless gripper is employed in various industries and handling of textile raw materials in specific wherever the high surface finishing is required. The vane gripper is modern tech tools applied in re-locating of components by creating gap between the gripper and component which produce negative pressure which is used for uplift of component. The uplift force is built by maintaining break between the vanes and the work-piece. The lifting force may be vary in accordance with the weight of the components, rpm of the motor used to rotate the vanes, distance available with the components and the vanes etc., The new gripper design is discussed in the following chapters and characteristics of the vanes are compared with parameters like lifting height, negative pressure value, clearance between the object and the vane.

Multi-objective structural optimization of a cyclone for an aggregate drying pulverised coal combustion device

ABSTRACTThe focus of this work is on the problem of the low efficiency and high pollution caused by the poor quality of coal, unstable loads and other factors in the pulverised coal combustion process. For this reason, a cyclone is installed at the second outlet of pulverised coal combustion devices. Multi-parameter and multi-objective optimizations were involved in the design of the cyclone. The influences of the structural parameters on the evaluation index have been rigorously analysed through the evaluation index of the internal flow field of the burner. Further, the genetic algorithm NSGA-II was applied to optimise the structural parameters of the cyclone based on Response Surface Model. The results showed that the outer diameter of the cyclone, the installation angle of the swirl vanes, and the number of swirl vanes had a significant impact on the combustion, as well as the NOX emission characteristics of pulverised coal. When the outer diameter of the cyclone was 500 mm, the number of swirl vanes was 12, and the installation angle of the swirl vanes was 48 degrees, the combustion efficiency of the pulverised coal burner was increased by 47.3%, and the NOX emissions were decreased by 19.1%.

Orthogonal experimental research on the structural parameters of a novel drill bit used for ice core drilling with air reverse circulation

AbstractA new type of ice core drill bit, designed with a vane swirler, was developed for ice core drilling with air reverse circulation. An orthogonal experimental design method was employed to investigate the effects of the swirler structure parameters on the reverse circulation performance of the drill bit including helical angle, number of blades, blade length and blade central angle, etc. The entrainment ratio was used to evaluate the reverse circulation effectiveness of the drill bit. The results show that the helical angle is the dominant factor regardless of whether or not the flushing nozzles are part of the design of the drill bit. The number of blades is the least important factor for the drill bit designed with the flushing nozzles (referred to as drill bit I), while the outlet area of the swirling slot is the least influential factor for the drill bit without flushing nozzles (referred to as drill bit П). In addition, the appearance of the ice core has a certain effect on the air reverse circulation for both drill bits. Within the ranges of this study, the optimal structure of the drill bit was determined based on the range analysis of the orthogonal design.