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Introduction
Fabio Martins currently works at Institute for Energy and Materials Processes, University of Duisburg-Essen. Fabio does research in the areas of turbulence, particle synthesis in spray flames and development of optical techniques.
Publications
Publications (63)
A practical method is presented to generate inflow boundary conditions for the laminar but spatially inhomogeneous flow out of filters, packed beds, or sinter plates. A synthetic velocity field that statistically reproduces the outflow characteristics is created based on digitally filtered random noise by the integral lengthscale of the investigate...
Turbulent spray flames issuing from the SpraySyn 2.0 burner were investigated in the present work by means of tomographic imaging using multi-simultaneous measurements (TIMes). This small-scale standard burner is designed to study flame-spray synthesis of tailored nanoparticle systems. The applied measurement technique
combined background-oriented...
A practical method is presented to generate inflow boundary conditions for the laminar but spatially inhomogeneous flow out of filters, packed beds, or sinter plates. A synthetic velocity field that statistically reproduces the outflow characteristics is created based on digitally filtered random noise by the integral lengthscale of the investigate...
Tomographic imaging using multi-simultaneous measurements (TIMes) is performed on the SPP1980 SpraySyn burner (first and second versions) under several operating conditions to analyse the flame morphology and its potential impact on the flame spray pyrolysis. Three types of single-shot and time-averaged 3D fields were obtained concurrently: (a) CH*...
Turbulent flows are characterized by diverse and unsteady three-dimensional features that require three-dimensional measurements to study. In case of non-isothermal flows, combined three-dimensional measurements of temperature and velocity are necessary. In this paper, a thermographic three-dimensional particle tracking velocimetry (thermographic 3...
The present work combines background-oriented schlieren tomography (BOST) with computed tomography of chemiluminescence (CTC) using the TIMes technique to provide simultaneous three-dimensional fields of refractive index (i.e., density) and CH* chemiluminescence (i.e., flame luminescence) on a single-shot basis. The feasibility of the proposed non-...
The synthesis of iron(III) oxide particulates from iron pentacarbonyl (IPC) in a flame spray pyrolysis process is predicted by a multiple mapping conditioning (MMC) method. MMC is coupled with carrier-phase large eddy simulations and a sectional description of the population balance equation. MMC is a sparse particle method, where the number of sto...
The process of fuel injection and the associated wall impact is critical for the quality of combustion in engines. Secondary droplets and wall deposits are strongly related to incomplete combustion and soot emissions. To reduce harmful emissions and optimise the combustion, further investigations of the processes of spray impingement, secondary dro...
Tomographic imaging using multi-simultaneous measurements of emissions is applied to three operating conditions of the SpraySyn burner in order to investigate the turbulent flame morphology and its potential impact on the flame spray pyrolysis. Instantaneous and time-averaged three-dimensional fields of CH* chemiluminescence (flame front marker) an...
The process of fuel injection and the associated wall impact is critical for the quality of combustion in engines. Secondary droplets and wall deposits are strongly related to incomplete combustion and soot emissions. To reduce harmful emissions and optimise the combustion, further investigations of the processes of spray impingement, secondary dro...
A concept for joined three-dimensional temperature and velocity measurements in turbulent gas flows using sub-micron sized thermographic phosphor tracer particles is presented. Such measurements are needed to resolve flow structures commonly encountered in turbulent flows of scientific and industrial interest. While available techniques for simulta...
Tomographic imaging using multi-simultaneous measurements (TIMes) of spontaneous light emission was performed on various operating conditions of the SpraySyn burner to analyse the flame morphology and its potential impact on spray flame pyrolysis. Concurrent instantaneous and time-averaged three-dimensional measurements of CH* chemiluminescence (fl...
In the present work, the synthesis of particulates in spray flames is simulated by coupling the multiple mapping conditioning (MMC) model with carrier phase large eddy simulations and a sectional description of the population balance equation. MMC is a sparse particle method, where the number of stochastic particles is heavily reduced in comparison...
Many flows of technical and scientific interest are intrinsically three-dimensional. Extracting slices using planar measurement techniques allows only a limited view into the flow physics and can introduce ambiguities while investigating the extent of 3D regions. Nowadays, thanks to tremendous progress in the field of volumetric velocimetry, full 3...
The main goal of this work was to obtain well-converged liquid velocity profiles for intermittent gas-liquid flows in a horizontal pipe. To this end, air and water with superficial velocities of J G = 0.5 m/s and J L = 0.3, 0.4 and 0.5 m/s, respectively, were driven into a 18-m acrylic test section with an inner diameter of 40 mm. All three-compone...
In the present work, a standard large eddy simulation is combined with tracer particle seeding simulations to investigate the different PIV bias errors introduced by intermittent particle seeding and particle lag. The intermittency effect is caused by evaluating the velocity from tracer particles with inertia in a region where streams mix with diff...
The two-dimensional multi-angle light scattering (2D-MALS) technique has been extended for single-shot size measurements of soot aggregates in flames. Six cameras are used for instantaneous acquisition of the elastic scattering from the aggregates at different directions between 10 to 90∘\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackag...
Helically coiled tubes are widely used in industry to enhance heat and mass transfer in the laminar flow regime, due to their secondary flow pattern. In this study, tomographic particle image velocimetry (tomo-PIV) is used in a horizontally coiled helical tube to systematically acquire 3C-3D velocity fields for Reynolds numbers ranging from 20 to 1...
The present study contributes to the characterization of the complex flow fields that arise from annular turbulent non-reacting and reacting jets dispersed through the SPP1980 SpraySyn-burner. The SpraySyn-burner is a new lab-scale standard burner to study the production of functional materials by flame spray pyrolysis. Velocity measurements of axi...
Gas-liquid two-phase flows are commonly encountered, both in nature and in many engineering applications. The complex characteristics of such flows requires its modelling to be supported by detailed experimental data. The present work describes
an experimental study of a horizontal, gas-liquid pipe flow in the intermittent regime. High-frequency st...
The random-in-appearance turbulent flow of boundary layers seem to display packages of organized coherent structures near the wall. The understanding of the generation and interaction of these structures and their contribution to the production and dissipation of turbulence is of great relevance to the modelling and control of wall-bounded flows. T...
Gas–liquid intermittent flows can be found in many engineering applications, nevertheless a detailed knowledge of this flow pattern is still not fully available. In the present work, an experimental study was conducted with the objective of developing a measurement procedure capable of providing ensemble-averaged three-component velocity fields in...
Gas-liquid intermittent flows in pipes are found in many engineering applications. Particularly basic experimental studies on the intermittent flow pattern in horizontal pipes, in which gas bubbles and liquid plugs flow in a transient manner, are of fundamental importance for the development of more accurate mathematical models of this complex phen...
The study of packed bed configurations for design optimization is of great practical relevance, because this configuration is applied in countless chemical processes. Many researchers have employed Particle Image Velocimetry in packed beds in order to measure 2D velocity fields. Due to the complex geometries and experimental constraints, most of th...
Packed beds are employed in a wide range of industrial processes, making their optimization an important objective. This requires a thorough understanding of the flow characteristics in the interstices of the bed and the influence of parameters such as packing material, fluid type and flow rate. Next to numerical simulations that have been performe...
We introduce two new criteria based on the work of Duchon and Robert (2000 Nonlinearity 13 249) and Eyink (2006 Phys. Rev. E 74 066302), which allow for the local detection of Navier–Stokes singularities in experimental flows. We discuss the difference between non-dissipative or dissipative Euler quasi-singularities and genuine Navier–Stokes dissip...
The fundamental study of turbulent structures near a wall is of significant importance due to its dominant role in innumerous engineering applications. In turbulent flows, eddies of different scales interact with each other in a complex phenomenon of a continuous self-sustaining process. Although the presence of patterns of coherent motion seem to...
We introduce two new singularity detection criteria based on the work of
Duchon-Robert (DR) [J. Duchon and R. Robert, Nonlinearity, 13, 249 (2000)], and
Eyink [G.L. Eyink, Phys. Rev. E, 74 (2006)] which allow for the local detection
of singularities with scaling exponent $h\leqslant1/2$ in experimental flows,
using PIV measurements. We show that in...
The fundamental study of the near-wall structure organization in turbulent flows is crucial to understand the self-generation process of turbulence. To investigate such phenomena, an experiment of high-repetition, 6-camera tomo-PIV in a boundary layer was performed. Vector fields generated from BIMART high-quality reconstructed volumes resulted in...
Tomographic PIV is a three-component volumetric velocity measurement technique based on the tomographic reconstruction of a particle distribution imaged by multiple camera views. In essence, the performance and accuracy of this technique is highly dependent on the parametric adjustment and the reconstruction algorithm used. Although synthetic data...
We studied horizontal two-phase flow of air and water in the transition from elongated bubble to the slug flow regimes.•Ensemble-averaged digital image processing techniques were developed and applied for detection of the liquid-gas interfaces.•Quantitative information on bubble nose and tail were obtained revealing their change with mixture veloci...
A non-intrusive optical technique was developed to provide time-resolved longitudinal and cross-sectional images of the liquid
film in horizontal annular pipe flow of air and water, revealing the interfacial wave behavior. Quantitative information on
the liquid film dynamics was extracted from the time-resolved images. The planar laser-induced fluo...
This paper presents two methods for accelerating the learning process of Reinforcement Learning - Neuro-Fuzzy Hierarchical Politree model (RL-NFHP): policy Q-DC-Roulette and early stopping. This model is used to provide an agent with intelligence, making it autonomous, due to the capacity of ratiocinate (infer actions) and learning, acquired knowle...
