Talbot interferometer with circular gratings for the measurement of temperature in axisymmetric gaseous flames (original) (raw)
Related papers
Digital holographic interferometry for measurement of temperature in axisymmetric flames
Applied Optics, 2012
In this paper, experimental investigations and analysis is presented to measure the temperature and temperature profile of gaseous flames using lensless Fourier transform digital holographic interferometry. The evaluations of the experimental results give the accuracy, sensitivity, spatial resolution, and range of measurements to be well within the experimental limits. Details of the experimental results and analysis are presented.
Optics and Lasers in Engineering, 2015
The effect of magnetic field on temperature and temperature profile of diffusion flame is investigated by using circular grating Talbot interferometer. Talbot interferometric fringes are recorded for diffusion flame generated by butane torch burner, in the absence of magnetic field, in the presence of uniform magnetic field, upward-decreasing and upward-increasing magnetic field. Analysis of recorded interferogram reveals that the temperature of the flame is increased under the influence of the upwarddecreasing magnetic field and flame temperature is decreased under the influence of upward-increasing magnetic field. Uniform magnetic field has a negligible effect on temperature of the flame.
The present work is concerned with the interferometric study of whole field temperature distribution during the combustion of liquid isopropyl nitrate (IPN) strand in a cuvette using a Mach Zehnder interferometer. Line-of-sight images of the flame zone have been recorded in real time using the interferometer. Experiments have been conducted in infinite as well as wedge fringe setting modes. Recorded interferograms have been quantitatively analyzed to retrieve the two-dimensional temperature distribution in the monopropellant flame for cuvette aspect ratios1, 2.5 and 3.7. This is done to reduce the errors caused due to refractive index change within the flame. Comparison with thermocouple readings shows best results with aspect ratio 3.7. The thermal analysis reveals the presence of a stretched monopropellant flame, formed by the decomposition of IPN to various products, surrounded by a diffusion flame, formed by further oxidation of the decomposition products. The flame stabilized above the cuvette could be distinctly subdivided into several zones based on luminosity.
Optics and Lasers in Engineering, 2011
The temperature field of a premixed methane symmetric laminar flame jet is visualized by studying the interferograms of the flame, using the Mach-Zehnder Interferometry. Two kinds of oxidizers are chosen for combustion: industrially pure oxygen and oxygen-enriched air. The flame is chosen to be both lean, and rich. For the lean oxygen-enriched combustion (OEC), the equivalence ratio was held constant at 0.5, and the oxygen enrichment was adjusted to 0.5 and 0.6, and for rich OEC, equivalence ratio is chosen to be 1.2 while the oxygen enrichment was 0.7 and 0.8. For methane/oxygen combustion, the equivalence ratio varied from 0.35 to 0.55 for the lean flame, and 1.3 and 1.7 for the rich flame. Attempt was made to keep the Reynolds number unchanged at 500, for OEC, and 1000, for methane/oxygen flame. In the present study a non-contact method is successfully developed to measure the temperature field of a premixed radially symmetric laminar methane flame jet. The effect of oxygen enrichment and equivalence ratio on temperature field is also investigated and depicted.
OSA Imaging and Applied Optics Congress 2021 (3D, COSI, DH, ISA, pcAOP), 2021
Measuremellt of accurate spa/wi distribution of temperature and temperclfllre flltclIlarion ill aflame is importam to study the cO/llbu~•tiol/ process ill detail. IlIlhis paper first we have presented nreasuremellt of temperarure profile of a gaseous fla/llf! of {I /Wodimellsional slot burner. The erm,.~, due to halu effect in the measuremellts oltemperature are minimized by correcting the width ofthe/rillges. Further single e).posure speckle photography is used to study temperarurej1uctlf(ltion illside thej1ame. The 3-D plot of temperature fluctuation for differem fuel flow rates of air alld aeety/elle at different vertical heights above the mouth of the bumer with distance from the one elld of the .burner is also presented.
SAE Technical Papers, 2004
Temperature distribution as the flame propagated and contacted to the wall of the combustion chamber was measured by real-time holographic interference method, which mainly consisted of an argon-ion laser and a highspeed video camera. The experiment was done with a constant volume chamber and propane-air mixture with several kinds of quivalence ratios. From the experimental results, it can be found that the temperature distribution outside the zone from the surface of the combustion chamber to 0.1mm distance could be measured by counting the number of the interference fringes, but couldn’t within this zone because of lacking in the resolution of the used optical system. The experimental results show that the temperature distribution when the heat flux on the wall increases rapidly and when the heat flux shows the maximum value are quite different by the equivalence ratio. Therefore, the temperature distribution when the heat flux shows the maximum is related with the lower temperature of ignition temperature.
Optik, 2018
In this paper an application of circular grating Talbot interferometer is investigated for measurement of temperature and temperature profile of micro flame under the influence of gradient and uniform magnetic field. Hilbert transform is used for phase extraction from a single Talbot interferometric fringe pattern. In addition to this a numerical study is undertaken to established the effect of magnetic field on flame flow characteristics such as flame length, fuel mass flow rate, magnetic susceptibility and mass fractions of oxygen which is the main oxidizer and products of combustion in candle flame is demonstrated. Experimental investigation reveals that the temperature of the flame is increased under the influence of the upward-decreasing magnetic field and decreased in upward-increasing magnetic field. In a uniform magnetic field the flame temperature is also increased, which is in contrast to the normal diffusion (large size) flame. The system is cost effective, easy to align, less prone to environmental perturbation and capable of measuring temperature of a large size (centimeter) flame to micro size (millimeter) flame.
Combustion and flame, 2002
Optical methods (such as holographic interferometry, speckle photography, speckle shearing interferometry, moiré deflectometry, rainbow Schlieren deflectometry and Talbot interferometry, and so forth) have the potential for accurately measuring the entire temperature field associated with multidimensional flames, which may be difficult to do using other techniques. These interferometric or deflectometric techniques first determine the refractive index in flames, and thereafter infer the temperature distribution. The relationship between the refractive index and temperature is obtained by using a state equation and the Gladstone-Dale relation. However, a potential source of error arises since the local composition of the flame being studied is usually unknown. In a previous investigation, we examined the occurrence of this error by assuming the local flame composition to be the same as that of air at the local temperature. This was examined through one-dimensional simulations of counterflow flames. We found that while calculating the temperature from the measured refractive index this assumption could lead to significant errors for some flames and to minimal errors in other flames. This investigation quantifies those errors in the context of two-dimensional flames in both planar and axisymmetric geometries. It is found that the refractive index values of a mixture are nearly identical with those of the refractive index of air for partially premixed flames (PPFs). The maximum error lies in the range of 6.3 to 10.7% for one-dimensional (1-D) counterflow PPFs, and between 6.1 to 8.0% for two-dimensional (2-D) planar and axisymmetric PPFs (for equivalence ratios in the range of 1.5 Յ r Յ 2.0). For nonpremixed flames, however, the maximum error can have values up to 33.8% and 34.5% for the 1-D and 2-D configurations, respectively. Therefore, the accurate inference of the temperature of nonpremixed flames from the measured refractive index distribution requires that an alternative approach be developed. We have developed an interpolation method that reduces the maximum error from 34.5% to 9.8% for these flames, and is associated with even smaller errors in most other regions of these flames.