Gas temperature in the trace of water droplets streamlined by hot air flow

Кузнецов, Г. В.; Стрижак, П. А.; Voytkov, I.S.

doi:10.1016/j.ijmultiphaseflow.2017.02.002

Cited by 15 publications

(10 citation statements)

References 16 publications

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“…To generate a sprayed water flow, we used a system comprised of a water reservoir, feeding channel, and spraying nozzle 12. The nozzle was the same as in [20,21]. To determine the droplet flow characteristics (droplet velocity U d and droplet radius R d ), we used a panoramic optical system.…”

Section: Dropletsmentioning

confidence: 99%

“…The temperature distribution (LIP measurement) and temperature trend (thermocouple measurement) obtained were processed similarly to [20,21] to determine the following parameters; ∆T a : temperature drop of combustion products or air in the trace of droplet flow relative to its initial value, • C; τ: low (relative to the initial) gas temperature lifetime in the trace of droplet flow, s. Parameter τ describes the time from the point when the temperature of combustion products started dropping, τ 1 (recording initiation at 0 s), until the time of the complete recovery of its initial value, τ 2 . The thermal trace of a droplet is defined as an area in the wake of droplet flow with a temperature at least 10 • C lower than the initial T a .…”

Section: Experimental Data Processingmentioning

confidence: 99%

“…Unlike in [20,21], for each of the measurement techniques in this research, we additionally calculated temperature fluctuation δT as a difference between maximum (T max ) and minimum (T min ) temperature readings in a single experiment (i.e., experimental temperature dispersion at identical initial conditions). We also calculated the difference (∆T) between the thermocouple (T Therm ) and LIP (T LIP ) measurement results.…”

Section: Experimental Data Processingmentioning

confidence: 99%

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Temperature Fields of the Droplets and Gases Mixture

2020

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In this research, we obtain gas–vapor mixture temperature fields generated by blending droplets and high-temperature combustion products. Similar experiments are conducted for droplet injection into heated air flow. This kind of measurement is essential for high-temperature and high-speed processes in contact heat exchangers or in liquid treatment chambers, as well as in firefighting systems. Experiments are conducted using an optical system based on Laser-Induced Phosphorescence as well as two types of thermocouples with a similar measurement range but different response times (0.1–3 s) and accuracy (1–5 °C). In our experiments, we inject droplets into the heated air flow (first scheme) and into the flow of high-temperature combustion products (second scheme). We concentrate on the unsteady inhomogeneous temperature fields of the gas–vapor mixture produced by blending the above-mentioned flows and monitoring the lifetime of the relatively low gas temperature after droplets passes through the observation area. The scientific novelty of this research comes from the first ever comparison of the temperature measurements of a gas–vapor–droplet mixture obtained by contact and non-contact systems. The advantages and limitations of the contact and non-contact techniques are defined for the measurement of gas–vapor mixture temperature.

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Section: Dropletsmentioning

confidence: 99%

Section: Experimental Data Processingmentioning

confidence: 99%

Section: Experimental Data Processingmentioning

confidence: 99%

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Temperature Fields of the Droplets and Gases Mixture

2020

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“…et al [ 21 , 22 , 23 ] showed that the evaporation rates of water droplets are significantly influenced by a buffer (vapor) layer around them, as well as by the unsteady and inhomogeneous nature of the temperature field generation of evaporating droplets. Based on the experimental data from [ 23 , 24 ], hypotheses were formulated about the unsteadiness and inhomogeneity of temperature fields of evaporating droplets, the dominance of their thermal insulation effects (limitations of the values of thermal flows supplied due to rapid vaporization). It is a pressing task to provide experimental grounds for the formulated hypotheses [ 23 , 24 ].…”

Section: Introductionmentioning

confidence: 99%

“…Based on the experimental data from [ 23 , 24 ], hypotheses were formulated about the unsteadiness and inhomogeneity of temperature fields of evaporating droplets, the dominance of their thermal insulation effects (limitations of the values of thermal flows supplied due to rapid vaporization). It is a pressing task to provide experimental grounds for the formulated hypotheses [ 23 , 24 ]. This will make it possible to develop models to predict the evaporation rates of liquid droplets in a wide temperature range (up to 2000 °C), covering all the promising heat technologies.…”

Section: Introductionmentioning

confidence: 99%

Gas-Vapor Mixture Temperature in the Near-Surface Layer of a Rapidly-Evaporating Water Droplet

Bellettre

Волков

2019

Entropy

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Mathematical modeling of the heat and mass transfer processes in the evaporating droplet–high-temperature gas medium system is difficult due to the need to describe the dynamics of the formation of the quasi-steady temperature field of evaporating droplets, as well as of a gas-vapor buffer layer around them and in their trace during evaporation in high-temperature gas flows. We used planar laser-induced fluorescence (PLIF) and laser-induced phosphorescence (LIP). The experiments were conducted with water droplets (initial radius 1–2 mm) heated in a hot air flow (temperature 20–500 °С, velocity 0.5–6 m/s). Unsteady temperature fields of water droplets and the gas-vapor mixture around them were recorded. High inhomogeneity of temperature fields under study has been validated. To determine the temperature in the so called dead zones, we solved the problem of heat transfer, in which the temperature in boundary conditions was set on the basis of experimental values.

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