Experimental Study on Instability Characteristics of Low-Swirl Flames in a Multinozzle Combustor With Different Swirling Arrays

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Weijie Liu ◽  
Bing Ge ◽  
Yinshen Tian ◽  
Shusheng Zang ◽  
Shilie Weng
Keyword(s):  
Experimental Study ◽  
Longitudinal Modes ◽  
Stable Operating ◽  
Wide Range ◽  
Index Distribution ◽  
Planar Laser ◽  
Combustion Region ◽  
Unstable Combustion ◽  
Flame Shape ◽  
Operating Window

This paper presents experimental study on self-excited combustion instability characteristics of premixed low-swirl flames in a multinozzle can combustor with counterswirl and coswirl arrays. Experiments were carried out over a wide range of inlet velocity from 4 m/s to 15.5 m/s and equivalence ratio from 0.5 to 0.85. Phase-locked OH planar laser-induced fluorescence was employed to measure flame shape and identify heat release rate. Four operation regions: stable combustion region, unstable combustion region, flashback region, and extinguish region are observed for both array burners. The amplitude of pressure fluctuation for counterswirl arrangement is less than the coswirl array, and the stable operating window of the counterswirl array is wider. In the unstable combustion region, the counterswirl flame triggers the 2L mode of the combustion system, while the coswirl flame incites three longitudinal modes with the highest amplitude near 3L. Rayleigh index distribution reveals neighboring flame interaction results in thermoacoustic coupling for multinozzle flames. Additionally, for the counterswirl array, thermoacoustic couplings also exit in the flame base region and shear region while, for the coswirl array, the instability driving zones also locate at the lip region and the tail of center flame which is totally different with counterswirl flame.

Experimental Study on Instability Characteristics of Low-Swirl Flames in a Multi-Nozzle Combustor With Different Swirling Arrays

2016 ◽  
Author(s):  
Weijie Liu ◽  
Bing Ge ◽  
Yinshen Tian ◽  
Shusheng Zang ◽  
Shilie Weng ◽  
...  
Keyword(s):  
Experimental Study ◽  
Combustion Instabilities ◽  
Longitudinal Modes ◽  
Stable Operating ◽  
Wide Range ◽  
Planar Laser ◽  
Combustion Region ◽  
Unstable Combustion ◽  
Fluctuation Amplitude ◽  
Operating Window

This paper presents experimental study on self-excited combustion instability characteristics of premixed low-swirl flames in a multi-nozzle can combustor with counter-swirl and co-swirl arrays. Experiments were carried out over a wide range of inlet velocity from 4 m/s to 15.5 m/s and equivalence ratio from 0.5 to 0.85. Phase-locked OH planar laser-induced fluorescence was employed to measure flame shape and identify heat release rate. Four operation regions: stable combustion region, unstable combustion region, flashback region and extinguish region are observed for both array burners. The stable operating window for counter-swirl array is wider compared to the co-swirl array. Pressure fluctuation amplitude for co-swirl burner is larger than the counter-swirl arrangement at the same operating condition. In the unstable combustion region, the counter-swirl flames trigger the 2L mode of the combustion system while co-swirl flames incite three longitudinal modes with the highest amplitude near 3L. Rayleigh index distribution reveals neighboring flame interaction results in thermoacoustic coupling for multi-nozzle flames. Additionally, for counter-swirl array, thermoacoustic couplings in flame base region and shear region are also the main reasons for inducing self-excited combustion instabilities. For co-swirl array, the instability driving zones also locate at the lip region and the tail of center flame.

scholarly journals Improvement of Pump Performance at Off-Design Conditions

1985 ◽  
Author(s):  
J. Paulon ◽  
C. Fradin ◽  
J. Poulain
Keyword(s):  
Experimental Study ◽  
Flow Field ◽  
Mass Flow ◽  
Flow Characteristic ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Pump Performance ◽  
Wide Range ◽  
Mass Flows ◽  
Design Value

Industrial pumps are generally used in a wide range of operating conditions from almost zero mass flow to mass flows larger than the design value. It has been often noted that the head-mass flow characteristic, at constant speed, presents a negative bump as the mass flow is somewhat smaller than the design mass flows. Flow and mechanical instabilities appear, which are unsafe for the facility. An experimental study has been undertaken in order to analyze and if possible to palliate these difficulties. A detailed flow analyzis has shown strong three dimensional effects and flow separations. From this better knowledge of the flow field, a particular device was designed and a strong attenuation of the negative bump was obtained.

scholarly journals Strength Comparison of FDM 3D Printed PLA Made by Different Manufacturers

TEM Journal ◽  
2020 ◽  
pp. 966-970
Author(s):  
Damir Hodžić ◽  
Adi Pandžić ◽  
Ismar Hajro ◽  
Petar Tasić
Keyword(s):  
Experimental Study ◽  
Additive Manufacturing ◽  
Fused Deposition Modelling ◽  
Fused Deposition ◽  
Manufacturing Technique ◽  
Plastic Materials ◽  
Wide Range ◽  
3D Printed ◽  
The Difference ◽  
Printing Parameters

Widely used additive manufacturing technique for plastic materials is Fused Deposition Modelling (FDM). The FDM technology has gained interest in industry for a wide range of applications, especially today when large number of different materials on the market are available. There are many different manufacturers for the same FDM material where the difference in price goes up to 50%. This experimental study investigates possible difference in strength of the 3D printed PLA material of five different manufacturers. All specimens are 3D printed on Ultimaker S5 printer with the same printing parameters, and they are all the same colour.

Multichannel random signal generation in optical fiber-based ring laser with quantum-dot semiconductor optical amplifier

2022 ◽  
Author(s):  
Kouichi AKAHANE ◽  
Atsushi Matsumoto ◽  
Umezawa Toshimasa ◽  
Naokatsu YAMAMOTO ◽  
Yuki Yata ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Random Number ◽  
Random Number Generation ◽  
Semiconductor Optical Amplifiers ◽  
Optical Amplifier ◽  
Random Signal ◽  
Signal Generation ◽  
Longitudinal Modes ◽  
Wide Range ◽  
The Individual

Abstract Random signal generation in a ring resonator laser is achieved with quantum-dot semiconductor optical amplifiers. The lasing spectra were obtained over a wide range of wavelength, and the individual longitudinal modes acted as the channels for random number generation.

scholarly journals An experimental study of the dynamics of ascent of the bubble system in the presence of a surfactant

2018 ◽  
Vol 194 ◽  
pp. 01002
Author(s):  
Alexandra Antonnikova ◽  
Sergey Basalaev ◽  
Anna Usanina ◽  
Eugene Maslov
Keyword(s):  
Experimental Study ◽  
Reynolds Numbers ◽  
Experimental Setup ◽  
Bubble Cluster ◽  
Bubble System ◽  
Wide Range ◽  
Compact Cluster ◽  
Glycerol Medium

This paper presents investigations on the new experimental setup for obtaining a compact cluster of monodisperse bubbles of a given diameter is presented. Also we provided the results of experimental study of the bubble cluster floating-up in the presence of a surfactant in a wide range of Reynolds numbers. There was held a comparison of the dynamics of the floating-up of a monodisperse bubble cluster in a glycerol medium and in the medium glycerin supplemented with a surfactant.

Experimental Study of Machining of Smart Materials Using Submerged Abrasive Waterjet Micromachining Process

2018 ◽  
Author(s):  
Sagil James ◽  
Anurag Mahajan
Keyword(s):  
Experimental Study ◽  
Smart Materials ◽  
Thermal Stresses ◽  
Piezoelectric Materials ◽  
High Hardness ◽  
Machining Process ◽  
Critical Parameters ◽  
Abrasive Waterjet ◽  
Parameter Study ◽  
Wide Range

Smart materials are new generation materials which possess great properties to mend themselves with a change in environment. Smart materials find applications in a wide range of industries including biomedical, aerospace, defense and energy sector and so on. These materials possess unique properties including high hardness, high strength, high melting point and low creep behavior. Manufacturing of these materials is a huge challenge, particularly at the micron scale. Abrasive waterjet micromachining (AWJMM) is a non-traditional material removal process which has the capability of machining extremely hard and brittle materials such as glasses and ceramics. AWJMM process is usually performed with nozzle and workpiece placed in air. However, machining in the air causes spreading of the waterjet resulting in low machining quality. Performing the AWJMM process with a submerged nozzle and workpiece could eliminate this problem and also reduce noise, splash, and airborne debris particles during the machining process. This research investigates Submerged Abrasive Waterjet Machining (SAWJMM) process for micromachining smart ceramic materials. The research involves experimental study on micromachining of smart materials using an in-house fabricated SAWJMM setup. The effect of critical parameters including stand-off distance, abrasive grain size and material properties on the cavity size, kerf angle and MRR during SAWJMM and AWJMM processes are studied. The study found that SAWJMM process is capable of successfully machining smart materials including shape memory alloys and piezoelectric materials at the micron scale. The machined surfaced are free of thermal stresses and did not show any cracking around the edges. The critical process parameter study revealed that stand-off distance and abrasive grit size significantly affect the machining results.

scholarly journals Robust Damping Controls for a Unified Power Flow Controller

2006 ◽  
Vol 6 (2) ◽  
Author(s):  
Abu H.M.A. Rahim ◽  
Jamil M Bakhashwain ◽  
Samir A Al-Baiyat
Keyword(s):  
Power Flow ◽  
Controller Design ◽  
Unified Power Flow Controller ◽  
Combined Application ◽  
Damping Control ◽  
Stable Operating ◽  
Wide Range ◽  
Fixed Parameter ◽  
Flow Controller ◽  
Power Flow Controller

This article investigates the various damping controls of the unified power flow controller (UPFC). A detailed dynamic model of the UPFC including the possible damping control parameters has been derived. A method of determining the stable operating states of the nonlinear system model has been presented. Fixed parameter robust controllers for the identified controls have been designed satisfying the robustness conditions on performance and stability. The robust controller design has been carried out with the aid of a simple graphical 'loop-shaping' construction procedure. Simulation studies show that both robust series converter voltage magnitude and shunt converter phase angle provide extremely good damping. Combined application of the above two controls, however, gives the best damping profile over a wide range of operation. PI controllers having optimized gain settings were employed to evaluate the robustness of the proposed controllers.

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