Comparison of holographic setups used in heat and mass transfer measurement (original) (raw)
Related papers
Use of Holographic Interferometry for Monitoring Heat Transfer
MM Science Journal, 2022
In the paper is described possibility of holographic interferometry in research of heat transfer above samples. Experiments with utilization of this method enable to explain many of actions going in environment and in phase interface between material and this environment in transport of heat. The presented experiments are aimed at verifying the possibilities of safe thermal loading of wood using with metal protective plate.
IntechOpen eBooks, 2023
Digital holographic interferometry (DHI) is used worldwide for many scientific and industrial applications. In DHI, two digital holograms; one in the reference/ambient state of the object and another in changed state of object are recorded by electronic imaging sensors (such as CCD/CMOS) as reference holograms and object holograms, respectively. Phase of object wavefronts in different states of the object is numerically reconstructed from digital holograms. The interference phase is reconstructed by subtracting the phase of reference hologram from the phase of object hologram, without performing any phase-shifting interferometry. Thus, no extra effort is needed in DHI for calculating the interference phase. Apart from direct reconstruction of interference phase from two digital holograms, the recent development, availability of recording devices at video rate, and high-performance computers make the measurements faster, reliable, robust, and even real-time. In this chapter, DHI is presented for the investigation of temperature distribution and heat transfer parameters such as natural convective heat transfer coefficient and local heat flux around the surface of industrial heated objects such as cylindrical wires and heat sinks.
Limits of Digital Holographic Interferometry used for Measurement of Temperature Fields
2018
Holographic interferometry (HI) is an optical measurement method that combines the principles of holography and classical interferometry. Compared to classical interferometry, two significant benefits are achieved. The first advantage is the ability to measure diffuse reflecting surfaces of objects, but this is not a matter of phase measurement. The second advantage is the fact that this is a differential technique. In principle, holographic interferometry, similar to classical interferometry, measures the change in the optical path of two waves. However, in classical interferometry, both optical paths of the interferometer must be optically equivalent, which means minimal difference in optical paths at each point. The resulting interferometric pattern is a combination of the measured deviation and variance introduced by the interferometer. Both deviations cannot be distinguished from one another. For this reason, the interferometer must be composed of highly accurate optical compon...
Temperature measurement by holographic interferometry in liquids
1995
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.
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.
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.
Digital holographic setups for phase object measurements in micro and macro scale
EPJ Web of Conferences, 2015
The measurement of properties of so called phase objects is being solved for more than one Century starting probably with schlieren technique 1. Classical interferometry served as a great measurement tool for several decades and was replaced by holographic interferometry, which disposes with many benefits when compared to classical interferometry. Holographic interferometry undergone an enormous development in last decade when digital holography has been established as a standard technique and most of the drawbacks were solved. The paper deals with scope of the huge applicability of digital holographic interferometry in heat and mass transfer measurement from micro to macro scale and from simple 2D measurement up to complex tomographic techniques. Recently the very complex experimental setups are under development in our labs combining many techniques leading to digital holographic micro tomography methods.
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.
Applied optics, 2014
In this paper, the local convective heat transfer coefficient (h) is measured along the surface of an electrically heated vertical wire using digital holographic interferometry (DHI). Experiments are conducted on wires of different diameters. The experimentally measured values are within the range as given in the literature. DHI is expected to provide a more accurate local convective heat transfer coefficient (h) as the value of the temperature gradient required for the calculation of "h" can be obtained more accurately than by other existing optical interferometric techniques without the use of a phase shifting technique. This is because in digital holography phase measurement accuracy is expected to be higher.