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A phase doppler anemometer (PDA) was used to determine the effects of evaporation on water spray for three rotary bell atomizer operational variable parameters: shaping air, bell speed and liquid flow. Shaping air was set at either 200 standard liters per minute (L/min) or 300 L/min, bell speed was set to 30, 40 or 50 thousand rotations per minute (krpm) and water flow rate was varied between 100, 200 or 300 cubic centimeters per minute (cm3/min). The total evaporation between 22.5 and 37.5 cm from the atomizer (cm3/s) was calculated for all the combinations of those variables. Evaporation rate increased with higher flow rate and bell speed but no statistically significant effects were obtained for variable shaping air on interactions between parameters.

The potential applications of three distinct photodetector types in laser Doppler anemometers for the measurement of hydrodynamic flow pulsations have been investigated. Laser Doppler anemometers with a classical vacuum photomultiplier tube, a multipixel silicon photomultiplier and a photomultiplier based on microchannel plates were used in the experiments. The main criteria for evaluating the quality of the Doppler signal were determined and analyzed for measuring the hydrodynamic flow velocity pulsations. The range of flow pulsations was from 1 to 50 Hz. In all experiments, laser Doppler anemometers demonstrated satisfactory performance when measuring pulsations up to 10 Hz. At frequencies from 10 to 50 Hz, the optimal results were achieved with laser Doppler anemometers employing photodetectors based on a silicon multipixel photomultiplier and a vacuum photomultiplier tube.

This work investigates how turbulence in open-channel flows is altered by the passage of surface waves by using experimental data collected with laboratory tests in a large-scale flume facility, wherein waves followed a current. Flow velocity data were measured with a laser Doppler anemometer and used to compute profiles of mean velocity and Reynolds stresses, and pre-multiplied spectra. The velocity signal containing contributions from the mean flow, wave motion and turbulence was decomposed using the empirical mode decomposition (EMD), which is considered a promising tool for the analysis of velocity time series measured in complex flows. A novel outer length scale $h_{0}$ is proposed which separates the flow into two regions depending on the competition between the vertical velocities associated with the wave motion and the turbulent velocities imposed by the current. This outer length scale allows for the identification of a genuine overlap layer and an insightful scaling of turbulent statistics in the current-dominated flow region (i.e. $y/h_{0} < 1$). As the wave contribution to the vertical velocity increases, the pre-multiplied spectra reveal two intriguing features: (i) in the current-dominated flow region, the very large-scale motions (VLSMs) are progressively weakened but attached eddies are still present; and (ii) in the wave-dominated flow region (i.e. $y/h_{0} > 1$), a new spectral signature associated with long turbulent structures (approximately 6 and 25 times the flow depth $h$) appears. These longitudinal structures present in the wave-dominated flow region seem to share many features with Langumir-type cells.

Experimental data for turbulent solid–liquid flow in a vertical pipe were collected for glass beads with diameters from 0.5 mm to 5 mm, at concentrations up to 2 % v/v, and Reynolds numbers from 200 000 to 350 000. In addition, data for crushed glass, steel shot and two sizes of stainless-steel cylinders were also collected. The experiments span from the intermediate to the inertia-dominated regimes, and the results include direct measurements for the pressure drops, the solids concentration and the three velocity components for each of the phases using laser Doppler velocimetry and phase Doppler anemometry. In addition, the results include the Reynolds stresses, the granular temperature, the kinetic energy and calculations for the turbulence modulation. The results show augmentation of turbulence for all the conditions studied. The velocity fluctuations for the solid and the liquid are reduced with increasing Reynolds numbers at all conditions. The Reynolds number dictates the behaviour of the relative velocity with concentration: for the Reynolds number of 350 000, the relative velocity increases with increasing concentrations, which can be explained by a decrease in the solid shear and an increase in the solid-phase pressure with rising concentration. In contrast, for the Reynolds number of 200 000, the relative velocity decreases with increasing concentrations, which can be attributed to an increase in drag force at higher concentration. The unique dataset presented begins to close the gap in knowledge for two-phase flow experimentation at concentrations above 0.7 % v/v and Reynolds numbers above 30 000.

This paper presents the most recent mathematical modelling and procedure for Laser-Doppler Anemometers (LDA) calibration used by the Brazilian National Institute of Metrology Institute, the National Institute of Metrology, Quality and Technology (Inmetro). Here we calculate the fringe spacing calibration coefficient (C ? ) and the Burst Spectrum Analyser (BSA) calibration coefficient (C ??? ). Using these two calibration coefficients we can calibrate a LDA in a determinate velocity range.

This article presents a comparative analysis of flow characteristics behind a hydraulic turbine runner in air and water. Swirling flow with a precessing vortex core (PVC) was investigated using a laser Doppler anemometer and pressure pulsation sensors. The experiments were conducted on aerodynamic and hydrodynamic test rigs over a wide range of hydraulic turbine operating conditions. Part-load modes of hydraulic turbine operation were investigated using the Fourier transform of pressure pulsations obtained from acoustic sensors. The features of the swirling flow were shown for the range of operating conditions from deep partl-load to overload.

The velocity profiles and volumetric concentrations were measured using a laser doppler anemometer for a vertically ascending two-phase liquid–liquid droplet flow in a cylindrical tube, where the density difference between the phases is relatively small. This regime simulates the flow of a two-phase gas–liquid mixture in microgravity. The small phase slip velocity was experimentally measured. New methods have been developed for using a laser doppler anemometer to measure the velocity and volumetric concentration of phases in a dispersed two-phase flow.

Nebulizers are medical devices for inhalation treatment that create an aerosol from liquid drug formulation. The efficacy of the treatment is dependent on the particle size distribution (PSD) of generated aerosol. PSD can be influenced by the inhalation flow rate as well. Within the here-presented study PSD of aerosol generated by nebulizer Pari LC Sprint Star was measured by Phase Doppler Anemometry for inhalation flowrate of 8; 12; 20 and 40 l/min. The nebulized solution consisted of a liposomal system (20 %) from dipalmitoylfosfatidylcholine (DPPC), phosphatidic acid (PA) and cholesterol (Chol), and MiliQ – ultrapure water (80 %). Slight dependence of PSD on inhalation flow rate was identified. With the increasing flow rate, the particle size of generated aerosol is decreasing. However, the change of Dv50 with the measured flow rates was smaller than 1 µm. According to the results, the change in particle size induced by flow rate will not have a significant impact on drug delivery.

PROCEEDINGS OF THE XXXII A.I.VE.LA. ANNUAL NATIONAL MEETING19-20 December 2024, Forlì, Italyhttps://www.aivela.org/aivela-xxxii-national-meeting/A.I.VE.LA. – the Italian Association of Laser Velocimetry and non-invasive diagnostics is a non-profit cultural association whose objective is to promote and support research in the field of non-contact or minimally invasive measurement techniques, particularly of electromagnetic-based and optical techniques.Through its Annual Meeting, AIVELA aims at creating an active and stimulating forum where current research results and technical advances can be exchanged and the development of new systems for laboratory use, field testing and industrial application can be promoted. The techniques addressed include Laser Doppler Anemometry – LDA, Phase Doppler Anemometry – PDA, Image Velocimetry – PIV, Flow visualization techniques, Spectroscopic measurement techniques (LIF, Raman, etc.), Laser Doppler Vibrometry – LDV, Speckle Pattern Interferometry – ESPI, Holographic techniques, Shearography, Digital Image Correlation – DIC, Moiré techniques, Structured light techniques, Infrared imaging, Photoelasticity, Image based measurement techniques, Ultrasonic sensing, Acoustic and Aeroacoustic measurements, etc.The first Annual Meeting was held back in October 1992 and, since then, the event has met large consensus among the research and scientific communities worldwide for the high scientific interest of the papers presented.List of SCIENTIFIC COMMITTEE, ORGANISING COMMITTEE and INVITED LECTURERS are available in this PDF.

Direct measurement of forces within the rough bed layer have been limited by previous spatial-averaging shear force studies. A highly sensitive force transducer assembled with a target sphere was used to measure and record the instantaneous three-dimensional forces of sediment at incipient motion. In the current study, a laser Doppler anemometer, ultrasonic displacement meter, and a force transducer accompanied by video recordings were used to experimentally investigate the incipient motion of sediment. The developed experimental setup have the potential to resolve and improve fundamental classical hypotheses regarding the incipient sediment motion. Experiments conducted in a large recirculating flume verified that the force transducer detects instantaneous forces at incipient motion under varies hydrodynamic conditions. Depth time series, instantaneous horizontal, vertical, and lateral forces are presented for dam-break and tidal breaking bores. Evidence suggests that the uplift vertical force plays an important role in destabilizing and in the incipient motion of particles. A sudden decrease in horizontal force was observed in tidal breaking bore due to flow reversal; however, a rapid rise was observed due to initial impact of dam-break bore. Bore velocity seems to have a larger effect on dam-break force than bore height. Furthermore, lateral force has the least influence during tidal breaking bore, while sediment particles are subjected to additional lateral force during dam-break bore.