Experimental Investigation of Ignition and LBO Characteristics of SPP Injector: The Effect of Pilot Stage Air Split Ratio

2018 ◽  
Author(s):  
Jinhu Yang ◽  
Cunxi Liu ◽  
Haowei Wu ◽  
Fuqiang Liu ◽  
Yong Mu ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Flow Structure ◽  
Research Work ◽  
Combustion Stability ◽  
Meridian Plane ◽  
Flame Stability ◽  
Local Flow ◽  
Fuel Distribution ◽  
Split Ratio ◽  
Pilot Fuel

The influence of PASR (Pilot stage Air Split Ratio) on the ignition and LBO (Lean Blow Out) performances is experimentally investigated for an SPP (Stratified Partially Premixed) injector in this paper. The pilot stage of the SPP injector comprises two axial air swirlers as well as an air blast prefilm atomizer for pilot fuel preparation. It is believed that the variation of the air split ratio between the outer swirler and the inner swirler of the pilot stage will transform the flow structure and fuel distribution of the local flame anchoring zone, and consequently improves or deteriorates the stability of the pilot flame. The ignition and LBO characteristics were measured for PASR = 8:2, 7:3 and 6:4, and several inexplicable but interesting results are observed. In order to make out the underlying reasons for the differences of the obtained ignition and LBO data, the velocity field and spray concentration at the meridian plane were acquired experimentally with the help of optical diagnostics at isothermal conditions. It it concluded that two dominant mechanisms of flame stability exist depending on the range of the injector pressure drop (Δ Psw/P3t). At low pressure drop of the injector, the flame stability is mainly affected by the fuel distribution, however, the flow structure will play a more important role at high Δ Psw/P3t in that it can transform the local flow structures around the pilot flame root. The inherent correlations between the combustion stability and the flow structure as well as the fuel distribution are disscussed and conclusions are drawn for this research work in the end of this paper.

scholarly journals Improving Blowout Performance of the Conical Swirler Combustor by Employing Two Parts of Fuel at Low Operating Condition

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1681
Author(s):  
Yixiang Yuan ◽  
Qinghua Zeng ◽  
Jun Yao ◽  
Yongjun Zhang ◽  
Mengmeng Zhao ◽  
...  
Keyword(s):  
Distribution Ratio ◽  
Performance Enhancement ◽  
Experimental Testing ◽  
Stability Boundary ◽  
Operating Conditions ◽  
Nox Emission ◽  
Combustion Stability ◽  
Gas Temperature ◽  
Contact Ratio ◽  
Fuel Distribution

Aiming at the problem of the narrow combustion stability boundary, a conical swirler was designed and constructed based on the concept of fuel distribution. The blowout performance was studied at specified low operating conditions by a combination of experimental testing and numerical simulations. Research results indicate that the technique of the fuel distribution can enhance the combustion stability and widen the boundary of flameout within the range of testing conditions. The increase of the fuel distribution ratio improves the combustion stability but leads to an increase in NOx emission simultaneously. The simulation results show the increase of the fuel distribution ratio causes contact ratio increase in the area of lower reference velocity and gas temperature increase. The increased contact ratio and temperature contribute to the blowout performance enhancement, which is identical to the analysis result of the Damkohler number. The reported work in this paper has potential application value for the development of an industrial burner and combustor with high stability and low NOx emission, especially when the combustion system is required to be stable and efficient at low working conditions.

Local Swirl Chamber Heat Transfer and Flow Structure at Different Reynolds Numbers

1999 ◽  
Vol 122 (2) ◽  
pp. 375-385 ◽  
Author(s):  
C. R. Hedlund ◽  
P. M. Ligrani
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Flow Structure ◽  
Flow Behavior ◽  
Turbine Blades ◽  
Reynolds Numbers ◽  
Local Flow ◽  
Flux Boundary Condition ◽  
Nusselt Numbers ◽  
Swirl Chamber

Local flow behavior and heat transfer results are presented from two swirl chambers, which model passages used to cool the leading edges of turbine blades in gas turbine engines. Flow results are obtained in an isothermal swirl chamber. Surface Nusselt number distributions are measured in a second swirl chamber (with a constant wall heat flux boundary condition) using infrared thermography in conjunction with thermocouples, energy balances, and in situ calibration procedures. In both cases, Reynolds numbers Re based on inlet duct characteristics range from 6000 to about 20,000. Bulk helical flow is produced in each chamber by two inlets, which are tangent to the swirl chamber circumference. Important changes to local and globally averaged surface Nusselt numbers, instantaneous flow structure from flow visualizations, and distributions of static pressure, total pressure, and circumferential velocity are observed throughout the swirl chambers as the Reynolds number increases. Of particular importance are increases of local surface Nusselt numbers (as well as ones globally averaged over the entire swirl chamber surface) with increasing Reynolds number. These are tied to increased advection, as well as important changes to vortex characteristics near the concave surfaces of the swirl chambers. Higher Re also give larger axial components of velocity, and increased turning of the flow from each inlet, which gives Go¨rtler vortex pair trajectories greater skewness as they are advected downstream of each inlet. [S0889-504X(00)00502-X]

scholarly journals Local Swirl Chamber Heat Transfer and Flow Structure at Different Reynolds Numbers

1999 ◽  
Author(s):  
C. R. Hedlund ◽  
P. M. Ligrani
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Flow Structure ◽  
Flow Behavior ◽  
Turbine Blades ◽  
Reynolds Numbers ◽  
Local Flow ◽  
Flux Boundary Condition ◽  
Nusselt Numbers ◽  
Swirl Chamber

Local flow behavior and heat transfer results are presented from two swirl chambers, which model passages used to cool the leading edges of turbine blades in gas turbine engines. Flow results are obtained in an isothermal swirl chamber. Surface Nusselt number distributions are measured in a second swirl chamber (with a constant wall beat flux boundary condition) using infrared thermography, in conjunction with thermocouples, energy balances, and in situ calibration procedures. In both cases, Reynolds numbers Re based on inlet duct characteristics range from 6000 to about 20000. Bulk helical flow is produced in each chamber by two inlets which ore tangent to the swirl chamber circumference. Important changes to local and globally-averaged surface Nusselt numbers, instantaneous flow structure from flow visualizations, and distributions of static pressure, total pressure, and circumferential velocity are observed throughout the swirl chambers as the Reynolds number increases. Of particular importance are increases of local surface Nusselt numbers (as well as ones globally-averaged over the entire swirl chamber surface) with increasing Reynolds number. These are tiad to increased advection, as well as important changes to vortex characteristics near the concave surfaces of the swirl chambers. Higher Re also give larger axial components of velocity, and increased turning of the flow from each inlet, which gives Görtler vnrtex pair trajectories greater skewness as they are advected downstream of each inlet.

scholarly journals Leakage Detection through HL in Gurthali Water Supply Distribution Network using EPANET

2020 ◽  
Vol 9 (3) ◽  
pp. 3558-3565
Keyword(s):  
Pressure Drop ◽  
Water Distribution ◽  
Distribution Network ◽  
Research Work ◽  
Water Distribution Network ◽  
Leak Detection ◽  
Head Loss ◽  
Hydraulic Model ◽  
Leakage Detection ◽  
Valve Control

Water distribution network (WDN) design of hydraulic model Gurthali, NARWANA-JIND, HARYANA and objective of this paper to detecting the leakage in it.In current research work to find out the Hl through normal valve and leak valve control setting with randomly value.To detect the Head Loss to usedDarcy Weisbach methodwhich calculate the major and minor loss with friction in pipes links. EPANET tool is used to create enlarge hydraulic model and simulate the data. All the pipes to be analysis unit head loss and nodes analysis head loss foe every houses. For leak detection, four normal valve include to compute head loss or pressure drop on nodes, pipes and leak detection valves. Also find out the pressure and head loss on the all nodes and pipes.MS Excel used for leak detection data, at the various head loss values in valves, nodes, pipes links. Plot the various graphs with head loss on valves which generated that HL reduces drastically

A numerical study on the flame characteristics and pollutant emissions in a premixed burner: Comparison between porous and solid bluff bodies

2019 ◽  
Vol 234 (3) ◽  
pp. 353-364 ◽  
Author(s):  
Mahdi Mollamahdi ◽  
Seyed Abdolmehdi Hashemi
Keyword(s):  
Pressure Drop ◽  
Combustion Chamber ◽  
Methane Conversion ◽  
Conversion Rate ◽  
Bluff Body ◽  
Pollutant Emissions ◽  
Outer Diameter ◽  
Flame Stability ◽  
Bluff Bodies ◽  
No Emissions

The effects of porous and solid bluff bodies in the combustion chamber on flame stability limits, gas and solid temperature distributions, pressure drop, methane conversion rate, and CO and NO emissions are examined numerically. The porous and solid bluff bodies are made of SiC with the inner diameter of 50 mm, the outer diameter of 90 mm, and the length of 22 mm. In this study, Renormalization Group k–ε is used for modeling of turbulence. Eddy dissipation concept is selected for modeling of the interaction between turbulence and chemistry. A reduced mechanism based on GRI 3.0 consisting of 16 species and 41 reactions is employed to model methane combustion. The results indicate that the upper flame stability limit can be diminished by adding porous bluff body in the combustion chamber instead of the solid bluff body. Besides, the pressure drop, CO and NO emissions in the combustion chamber with solid bluff body are higher than those of porous bluff body, while the methane conversion rate increases by replacing porous bluff body instead of solid bluff body in the combustion chamber.

Nusselt Numbers and Flow Structure on and Above a Shallow Dimpled Surface Within a Channel Including Effects of Inlet Turbulence Intensity Level

2004 ◽  
Vol 127 (2) ◽  
pp. 321-330 ◽  
Author(s):  
P. M. Ligrani ◽  
N. K. Burgess ◽  
S. Y. Won
Keyword(s):  
Nusselt Number ◽  
Flow Structure ◽  
Turbulence Intensity ◽  
Local Nusselt Number ◽  
Channel Height ◽  
Intensity Level ◽  
Stagnation Temperature ◽  
Channel Inlet ◽  
Local Flow ◽  
Nusselt Numbers

Experimental results from a channel with shallow dimples placed on one wall are given for Reynolds numbers based on channel height from 3,700 to 20,000, levels of longitudinal turbulence intensity from 3% to 11% (at the entrance of the channel test section), and a ratio of air inlet stagnation temperature to surface temperature of approximately 0.94. The ratio of dimple depth to dimple print diameter δ∕D is 0.1, and the ratio of channel height to dimple print diameter H∕D is 1.00. The data presented include friction factors, local Nusselt numbers, spatially averaged Nusselt numbers, a number of time-averaged flow structural characteristics, flow visualization results, and spectra of longitudinal velocity fluctuations which, at a Reynolds number of 20,000, show a primary vortex shedding frequency of 8.0Hz and a dimple edge vortex pair oscillation frequency of approximately 6.5Hz. The local flow structure shows some qualitative similarity to characteristics measured with deeper dimples (δ∕D of 0.2 and 0.3), with smaller quantitative changes from the dimples as δ∕D decreases. A similar conclusion is reached regarding qualitative and quantitative variations of local Nusselt number ratio data, which show that the highest local values are present within the downstream portions of dimples, as well as near dimple spanwise and downstream edges. Local and spatially averaged Nusselt number ratios sometimes change by small amounts as the channel inlet turbulence intensity level is altered, whereas friction factor ratios increase somewhat at the channel inlet turbulence intensity level increases. These changes to local Nusselt number data (with changing turbulence intensity level) are present at the same locations where the vortex pairs appear to originate, where they have the greatest influences on local flow and heat transfer behavior.

Shape Optimization of Multi-Chamber Mufflers With Plug-Inlet Tube on a Venting Process by Genetic Algorithms

2009 ◽  
Author(s):  
Min-Chie Chiu
Keyword(s):  
Pressure Drop ◽  
Shape Optimization ◽  
Research Work ◽  
Back Pressure ◽  
Transmission Losses ◽  
New Techniques ◽  
Inlet Tube ◽  
Pure Tones ◽  
The Mathematical Model ◽  
Perforated Tube

Research on new techniques of single-chamber plug-inlet mufflers has been addressed. However, research work on shape optimization of multi-chamber plug-inlet mufflers along with work on the maximal back pressure has been neglected. Therefore, a numerical case for eliminating a broadband steam blow-off noise using multi-chamber plug-inlet mufflers in conjunction with genetic algorithm (GA) as well as numerical decoupling technique under space-constrained pressure drop is introduced in this paper. To verify the liability of GA optimization, optimal noise abatements for various pure tones on a one-chamber plug-inlet muffler are exemplified. Also, the accuracy of the mathematical model has to be checked by experimental data. Results indicate that the maximal sound transmission losses are precisely located at the desired target tones. Consequently, both the pressure drop and the acoustical performance will be increased when the diameters (at inlet tubes and perforated holes), the perforated ratio, and the length of perforated tube decrease.

Impact of Bifurcation Angle and Inlet Reynolds Number on Local Pressure Recovery in Biologically-Inspired Flow Networks

2017 ◽  
Author(s):  
Subhadeep Koner ◽  
David Calamas ◽  
Daniel Dannelley
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Wall Temperature ◽  
Flow Behavior ◽  
Flow Networks ◽  
Local Pressure ◽  
Biologically Inspired ◽  
Local Flow ◽  
Bifurcation Angle ◽  
Microscale Flow

This work computationally investigates local flow behavior in tree-like flow networks of varying scale, bifurcation angle, and inlet Reynolds number. The performance of the tree-like flow networks were evaluated based on pressure drop and wall temperature distributions. Microscale, mesoscale, and macroscale tree-like flow networks, composed of a range of symmetric bifurcation angles (15, 30, 45, 60, 75, and 90°) and subject to a range of inlet Reynolds numbers (1000, 2000, 4000, 10000, and 20000) were evaluated. Local pressure recoveries were evident at bifurcations, regardless of scale and bifurcation angle which may result in a lower total pressure drop when compared with traditional parallel channel networks. Similarly, wall temperature spikes were also present immediately following bifurcations due to flow separation and recirculation. The magnitude of the wall temperature increases at bifurcations was dependent upon both bifurcation angle and scale. When compared with mesoscale and macroscale flow networks, microscale flow networks resulted in the largest local pressure recoveries and the smallest temperature jumps at bifurcations. Thus, while biologically-inspired flow networks offer the same advantages at all scales, the greatest performance increases are achieved at microscale.

Analysis of Local Flow Structure and Global Compressor Performance During Rotating Stall

2004 ◽  
Author(s):  
Chiara Palomba
Keyword(s):  
Flow Field ◽  
Flow Structure ◽  
Rotational Speed ◽  
Axial Flow ◽  
Rotating Stall ◽  
Performance Parameters ◽  
Flow Conditions ◽  
Local Flow ◽  
Flow Parameters ◽  
Compressor Performance

Rotating stall is an instability phenomenon that arises in axial flow compressors when the flow is reduced at constant rotational speed. It is characterised by the onset of rotating perturbations in the flow field accompanied by either an abrupt or gradual decrease of performances. Although the flow field is unsteady and non axisymmetric, the global operating point is stable and a stalled branch of performance curve may be experimentally determined. The number, rotational speed, circumferential extension of the rotating perturbed flow regions named rotating cells may vary from one compressor to another and may depend on the throttle position. The present work focuses on the interaction between local flow parameters and global compressor performance parameters with the aim of reaching a better understanding of the phenomenon. Starting from the Day, Greitzer and Cumpsty [1] model the detailed flow conditions during rotating stall are studied and related to the global performance parameters. This is done both to verify if the compressor under examination fits to the model and if the detailed flow structure may highlight the physics that in the simple model may hide behind the correlation’s used.

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