Measurement of a Temperature Field Generated by a Synthetic Jet Actuator using Digital Holographic Interferometry (original) (raw)
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Digital Holographic Interferometry for the Measurement of Symmetrical Temperature Fields in Liquids
2021
In this paper, we present a method of quantitatively measuring in real-time the dynamic temperature field change and visualization of volumetric temperature fields generated by a 2D axial-symmetric heated fluid from a pulsatile jet in a water tank through off-axis digital holographic interferometry. A Mach-Zehnder interferometer on portable platform was built for the experimental investigation. The pulsatile jet was submerged in a water tank and fed with water with higher temperature. Tomographic approach was used to reconstruct the temperature fields through the Abel Transform and the filtered back-projection. Averaged results, tomographic view, standard deviation and errors are presented. The presented results reveal digital holographic interferometry as a powerful technique to visualize temperature fields in flowing liquids and gases.
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.
Digital holografic interferometry used for identification of 2D temperature field
EPJ Web of Conferences, 2012
The presented paper shows the possibility of digital holographic interferometry application in measurement of unsteady 2D temperature field generated by pulsatile flow which is impinging heated surface. Special holographic setup with double sensitivity was developed instead of the commonly used Mach-Zehnder type of holographic interferometer in order to attain the parameters sufficient for the studied case. This setup is not light efficient like the Mach-Zehnder type but has double sensitivity. The results from the digital holographic interferometry experiments are perfected by measurement of the velocity field achieved by methods of hot-wire anemometry.
Measurement of temperature fields by holographic tomography
Experimental Thermal and Fluid Science, 1991
Tomographic methods are used to visualize three-dimensional fields of temperature in moving fluids as functions of time. They require a signal and a sensor for measurement purposes. The signal should be time-dependent and related to each differential volume of space. Therefore, in many cases coherent monochromatic light emitted by a laser was used to penetrate the fluid volume under investigation. The light was split into a large number of beams. The temperature field caused a change in the refractive index of the transparent fluid. The variation of the refractive index with time is indicated by a shift of the wavefront of each light beam. The sensors needed to record the variation in refractive index as a function of temperature and time are interferograms, one for each light beam taken at the same time, which are stored on photographic plates called holograms. The interferometric line patterns are digitized and numerically analyzed by computer to obtain the visualization of one three-dimensional temperature field.
Temperature measurement by holographic interferometry in liquids for transient flame spread
1994
This investigation developed a systematic method to measure the temperatures and the mass concentrations of local species in a nonpremixed ethylene-air flame using the holographic interferometry (HI) technique. A nearly linear state relationship between the Gladstone-Dale constant and the mixture fraction was deduced. Normalized state relationships between the refractive index and the mixture fraction were established from detailed combustion simulations for the NPFs. The maximum error of temperature caused by the assumption of composition of air was reduced from 48.84% to under 1.6% for the NPFs using the systematic method. The method can overcome the difficulty that the concentrations of local species must be known when measuring the temperature by HI for NPFs.
Temperature measurement in laminar free convective flow using digital holography
Applied Optics, 2009
A method for measurement of temperature in laminar free convection flow of water is presented using digital holographic interferometry. The method is relatively simple and fast because the method uses lensless Fourier transform digital holography, for which the reconstruction algorithm is simple and fast, and also the method does not require use of any extra experimental efforts as in phase shifting. The quantitative unwrapped phase difference is calculated experimentally from two digital holograms recorded in two different states of water-one in the quiescent state, the other in the laminar free convection. Unknown temperature in laminar free convection is measured quantitatively using a known value of temperature in the quiescent state from the unwrapped phase difference, where the equation by Tilton and Taylor describing the variation of refractive index of water with temperature is used to connect the phase with temperature. Experiments are also performed to visualize the turbulent free convection flow.
International Journal of Heat and Mass Transfer, 2012
The Confocal Scanning Laser Holography (CSLH) microscope was designed to measure the temperature distribution of a fluid in three dimensions using a focused laser beam. The laser beam passes through the specimen and is interfered with a reference beam to form a hologram. The minute changes in refractive index produce fringe-shifts in a hologram. The fringe-shifts are converted to temperature, pressure, or composition depending on the configuration. A tomographic reconstruction algorithm, which is based on the numerical aperture of the beam, was derived for the microscope. Narrow field angle scanning is restricted to the numerical aperture or cone angle of the laser beam probing the specimen which increases the error in determining the three-dimensional properties of a specimen. The holography aspect of the microscope preserves the phase of the object which provides a temperature sensitivity of 0.1°C based on a k/10 wave fringe shift resolution in the hologram. The reconstructed temperature resolution is 1°C in three-dimensions by processing the experiment data. The CSLH concept and tomographic reconstruction method of hologram data can be applied to precise non-invasive measurement of displacement, temperature, pressure, and composition of thick regions with positional resolution near the wavelength of the laser beam. Micro-fluidics and other areas of research and applied technology may well consider the unique measurement benefits of the CSLH device.
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.