Flow disturbance due to presence of the vane anemometer

Rachalski

Wodziak

2021

Sensors

This paper presents a method of measuring gas flow velocity based on the thermal time-of-flight method. The essence of the solution is an analysis of the time shift and the shape of voltage signals at the transmitter and at a temperature wave detector. The measurements used a probe composed of a wave transmitter and a detector, both in the form of thin tungsten wires. A rectangular signal was used at the wave transmitter. The time-of-flight of the wave was determined on the basis of the time shift of two selected characteristic points of the voltage waveform at the transmitter and the wave detector. To obtain the correct velocity indication, a correction in the form of a simple power function was applied. From the measurements performed, the relative uncertainty of the method was obtained, from approx. 4% of the measured value at an inflow velocity of 6.5 cm/s to 1% for an inflow velocity of 50 cm/s and higher.

Section: Methodsmentioning

confidence: 99%

A Semi-Empirical Approach to Gas Flow Velocity Measurement by Means of the Thermal Time-of-Flight Method

Rachalski

Wodziak

2021

Sensors

“…2b. The free stream velocity of the tunnel varied from 0.1 to 62 m/s, and the longitudinal free stream turbulence intensity was less than 0.5% (Bujalski et al, 2014). The systems dedicated to control temperature and relative humidity was installed in the wind tunnel.…”

Section: Methodsmentioning

confidence: 99%

Computational domain discretization for CFD analysis of flow in a granular packed bed

Sosnowski

Gnatowska

Journal of Theoretical and Applied Mechanics

et al. 2019

The paper reports results of an analysis concerning the infuence of a computational domain discretization method on the numerical stability of a model as well as the calculation error. The topology of a packed bed of a granular material consisting of granules contacting tangentially in one point makes the modeling of heat and mass transfer due to the fluid flow in such a domain a chalenging task. Therefore, the contribution of this paper constitutes a summary of discretization methods with discussion and guidelines allowing one to effectively select the most favourable method dedicated to discretization of the domain. The validation using Particle Image Velocimetry and evaluation of the impact of inflow velocity on the experimental and numerical research results are also presented in the paper.

“…Measurements were carried out on two measuring stands. The first was the TAN-POZ wind tunnel (Strata Mechanics Research Institute of the Polish Academy of Sciences, Krakow, Poland) [40]. The inflow velocity was controlled using a Schmidt thermal anemometer (model SS 20.500), whose measurement range is 0.07-2.50 m/s, and measurement uncertainty is 1.5% of the indicated value but not less than 0.02 m/s.…”

Section: Measurement Standmentioning

confidence: 99%

Semi-Empirical Approach to Gas Flow Velocity Measurement by Means of the Thermal Time-of-Flight Method—Further Investigation

2022

Energies

This paper describes a study to expand the knowledge as to whether a thermal wave anemometer can be used to measure the velocity of flowing gases or gas mixtures in situ. For this purpose, several series of measurements were performed in laboratory conditions using both the previously used probe and other probes of similar design. The probes were not modified mechanically or electrically in any way. The obtained results were compared with each other, and on this basis, the optimal, though purely empirical, form of the calibration function was determined (4). The analysis of the relative differences between the measured and set velocity values showed that they do not exceed 1% in the velocity range from 0.05 to 2.5 m/s. Lowering the sensitivity of the method for velocities below approx. 0.05 m/s results in a rapid increase in the observed deviations, reaching 15% for 0.015 m/s. The conducted research also revealed an increased resistance of the proposed measurement method to small flow disturbances, both longitudinal and transverse, and a reduced sensitivity to non-optimal positioning of the probe in relation to the flow direction, relative to the methods using both detectors.