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Linear and Non-Linear Rheological Properties of Foods
Published in Dennis R. Heldman, Daryl B. Lund, Cristina M. Sabliov, Handbook of Food Engineering, 2018
Ozlem C. Duvarci, Gamze Yazar, Hulya Dogan, Jozef L. Kokini
Several measurements and visualization techniques have been utilized to experimentally validate numerical simulation results and gain a deeper understanding of the processes involved in flow and mixing, such as measurements of velocities, at either specific points or through an entire plane, pressure and residence time. Flow visualization can be achieved using acid-base reactions or the diffusion of a dye in a flow and then using imaging techniques to capture the flow patterns. Velocity measurement has traditionally been carried out at point locations using Laser Doppler Velocimetry (LDA). Velocity measurements through entire planar cross-sections are done using Particle Image or Tracking Velocimetry (PIV) and Planar Laser-Induced Fluorescence (PLIF).
Applications
Published in Raj P. Chhabra, CRC Handbook of Thermal Engineering Second Edition, 2017
Joshua D. Ramsey, Ken Bell, Ramesh K. Shah, Bengt Sundén, Zan Wu, Clement Kleinstreuer, Zelin Xu, D. Ian Wilson, Graham T. Polley, John A. Pearce, Kenneth R. Diller, Jonathan W. Valvano, David W. Yarbrough, Moncef Krarti, John Zhai, Jan Kośny, Christian K. Bach, Ian H. Bell, Craig R. Bradshaw, Eckhard A. Groll, Abhinav Krishna, Orkan Kurtulus, Margaret M. Mathison, Bryce Shaffer, Bin Yang, Xinye Zhang, Davide Ziviani, Robert F. Boehm, Anthony F. Mills, Santanu Bandyopadhyay, Shankar Narasimhan, Donald L. Fenton, Raj M. Manglik, Sameer Khandekar, Mario F. Trujillo, Rolf D. Reitz, Milind A. Jog, Prabhat Kumar, K.P. Sandeep, Sanjiv Sinha, Krishna Valavala, Jun Ma, Pradeep Lall, Harold R. Jacobs, Mangesh Chaudhari, Amit Agrawal, Robert J. Moffat, Tadhg O’Donovan, Jungho Kim, S.A. Sherif, Alan T. McDonald, Arturo Pacheco-Vega, Gerardo Diaz, Mihir Sen, K.T. Yang, Martine Rueff, Evelyne Mauret, Pawel Wawrzyniak, Ireneusz Zbicinski, Mariia Sobulska, P.S. Ghoshdastidar, Naveen Tiwari, Rajappa Tadepalli, Raj Ganesh S. Pala, Desh Bandhu Singh, G. N. Tiwari
Surface temperatures and gas temperatures can be deduced from radiation measurements. Surface-temperature measurements are based on the emitted infrared energy, while gas-temperature measurements use specific emission lines from the gas itself or from a tracer inserted into the gas. Radiation devices, such as pyrometers for surface-temperature measurement systems (single-point), are commercially available, at low cost, which can measure temperature to ±1.5% of reading or 1.5°C (whichever is greater), above 0°C, if the emissivity of the surface is known. The device referenced requires a spot size of 1.9 cm diameter, viewed from 95 cm. Spectroscopic gas-temperature measurements can be accurate to ±3 or 4% of reading, but require a significant investment in effort as well as equipment (on the order of 1– 2 years and $100,000–$200,000). Several techniques based on Raman scattering have been used in combustion systems. Planar-laser-induced fluorescence has shown considerable promise as one of the newer methods.
Flow Visualization
Published in Jochen Aberle, Colin D. Rennie, David M. Admiraal, Marian Muste, Experimental Hydraulics: Methods, Instrumentation, Data Processing and Management, 2017
Jochen Aberle, Colin D. Rennie, David M. Admiraal, Marian Muste
Laser induced fluorescence measurements may be performed for points, lines, planes, and volumes within the flow; however, planar laser induced fluorescence (PLIF) is most frequently used. The imaging configuration for quantitative PLIF is the same as that for qualitative flow visualization using laser sheets for illumination; however, accurate measurements require significant refinements. A fluorescent dye such as fluorescein, rhodamine B or rhodamine 6G is used as the tracer. Most PLIF experiments use argon ion lasers as the illumination source due to their long-term stability and superior beam characteristics (Crimaldi, 2008). The 488 nm argon ion emission is also very close to the peak in the absorption band of fluorescein. Pulsed lasers (e.g., Nd:YAG) are also often used but usually must be operated at high intensities in order to produce sufficient energy, due to their very short pulse durations. This can cause nonlinear saturation effects in the dye, as described below, and pulse-to-pulse intensity variations may also be important, especially when the lasers are not operated near their design repetition rate.
Effect of DC Electric Field on Turbulent Flame Structure and Turbulent Burning Velocity
Published in Combustion Science and Technology, 2023
Yiming Li, Jinhua Wang, Hao Xia, Rongyuan Ju, Jinlu Yu, Haibao Mu, Zuohua Huang
The main objective of this work is to investigate the effect of electric field assisted on the turbulent premixed flame structure and turbulent burning velocity with different turbulence. Turbulent premixed Bunsen flame was used for well-controlled turbulence scale and intensity at the same bulk flow velocity because the effect of electric field would be affected by flow velocity. Instantaneous flame front structure was measured with OH-PLIF (Planar Laser-Induced Fluorescence). Flame front structure and turbulent burning velocity were derived to estimate the effect of electric field on turbulent flame. The similar and different effect of electric induced flow and turbulence on turbulent flame structure were investigated, and the underlying reasons for the mitigate effect of electric field with turbulence intensity were proposed.
Experiments on two-layer stratified gravity currents in the slumping phase
Published in Journal of Hydraulic Research, 2020
In the literature, a number of studies have been focused on quantifying the entrainment coefficients through the volume-based entrainment method or measuring the ratio of mixing layer thicknesses (e.g. Dimotakis, 2000; Ellison & Turner, 1959; Koochesfahani & Dimotakis, 1986; Samasiri & Woods, 2015). More recent investigation on quantifying the mixing dynamics uses the particle image velocimetry and planar laser induced fluorescence measurement technique simultaneously (Balasubramanian & Zhong, 2018). In this study, our objective is to deepen the understanding of gravity currents produced from two-layer stratified sources propagating in the slumping phase by identifying how the two dimensionless parameters, and , influence the Froude number in the slumping phase and the flow morphology through qualitative observations based on our experiments. The paper is organized as follows. In Section 2, the experimental set-up and procedures for the stratified gravity currents in the slumping phase are described. In Section 3, the results on selected cases to illustrate different flow morphologies and Froude number in the slumping phase are presented. Conclusions are made in Section 4.
Experimental data-based reduced-order model for analysis and prediction of flame transition in gas turbine combustors
Published in Combustion Theory and Modelling, 2019
Shivam Barwey, Malik Hassanaly, Qiang An, Venkat Raman, Adam Steinberg
In this study, CROM is used to develop a means for transition mechanism analysis and to model flame topology transition in a swirl combustor. Experimental stereoscopic particle image velocimetry (S-PIV) and OH planar laser induced fluorescence (PLIF) images are used to develop a predictive ROM for flame transition. The flow modes obtained are analysed to illustrate the physical information that can be obtained from the CROM methodology. The remainder of this paper is organised as follows: experimental data and operating conditions are provided in Section 2; the CROM methodology is discussed in Section 3; outcomes of the CROM approach are used to gain physical intuition about the flame transition mechanism in Section 4; results of the CROM approach both in terms of the prediction horizon time and forecast capability for different data types are discussed in Section 5. Finally, conclusions and future directions are presented in Section 6.