mod_eprivacy

Scientific Data in Subproject B1

Description

General Informations on the Datasets

The data are an excerpt of the experimental and numerical investigation in Subproject B1 concerning the evaporation of freely suspended supercooled water droplets at varying relative humidities and ambient temperatures. The data is suitable for the validation of numerical codes and experiments. Further information about the experimental setup can be found in: http://dx.doi.org/10.1016/j.icheatmasstransfer.2016.08.005

Experimental setup and results

In the experiment, single water droplets are optically levitated with a focused laser (λ=532nm). The uploaded data contains the experiments at the ambient temperature T=5°C for varying relative humidity. Each experiment is stored in a folder named considering the ambient conditions, e.g. „Temp_-10_RH_47“. A CCD camera (2048 pixel) records the elastically scattered light for about 12 s, which equals 60.000 lines. The measurement data and the evaluated data for each measurement is stored in a Matlab file, containing the following variables:

abstaende_grad

Mean distance between two maxima in degree at time t

angle

Observation angle of camera

beta

Evaporation rate in µm²/s

D

Calculated diameter at time t

D0

Extrapolated diameter at time t=0s

D_D0

Non dimensional diameter D/D0 at time t

ende_corr

End of correlation window to derive the evporation rate β

filterWindowSize

Window with for filter (filtfilt)

ImageMatrix

Raw data from CCD Kamera

n

Calculated real refractive index, see publication

p

Ambient pressure in Pa

phi_inf

Relative humidity

start_corr

Begin of correlation window to derive the evaporation rate β

t

Time at which the camera recorded a line

t_D0

Time t divided by initial diameter, t/D02

T_inf

Ambient temperature

T_wetbulb

Calculated wet-bulb temperature in K

The folder position includes the measurement data from the oscilloscope for each measurement. Channel 1 (CH1) is the position of the droplet in Volt and channel 2 (CH2) corresponds to the intensity of the scattered light under an angle of 90° in Volt. CH_Time is the time base of the oscilloscope.

Numerical setup and results

The simulation is performed on a Cartesian, three dimensional grid. The grid resolution is 512 x 256 x 256 cells. The setup for the simulation is an inflow on the left and an outflow on the right hand side. Free slip conditions are used on all lateral boundaries. An additional damping zone avoids undesired back flow. The initial water droplet is levitated in a nitrogen atmosphere and has a diameter of 50 µm. The ambient temperature is 268.15 K, the droplet is initialized with the wet bulb temperature which is 263.15 K. The ambient pressure is 0.965 bar. The inflow velocity is constant and has a value of 0.5 cm/s. The initial humidity of the atmosphere is 0%.

Download

If you have an account the raw data can be downloaded here.

Wednesday, November 13, 2019