Insertion depth effect and blockage effect for vane and cup anemometers
Project Description
Measurement error of 4 vane anemometers will be measured as a function of their insertion depth in the participating wind tunnels. The effect of flow pattern around a mounting rod to the meter indication will be investigated in this way. Air velocity fields in front of 3 anemometers will be measured by several participants too. The blockage effect in wind tunnels with different test section type and size will be investigated in this way.
Final Report 2026-04-10
The project has been completed and the report can be downloaded here>>.
Project data: SUP1_insertion_depth
Project data: SUP2_velocity_fields
Two effects influencing accuracy of anemometer calibrations have been investigated – the insertion depth effect and blockage effect.
Four types of vane anemometers and several configurations of cup anemometers were tested for the insertion depth effect in nine European wind tunnels.
Besides the significant sensitivity of the anemometers reading to their insertion depth in the wind tunnels, which was known already before, a new finding was achieved that the anemometers reading is sensitive also to a presence or absence of a wall at a test section boundary even if the anemometer sensor is far enough from the boundary not to be affected by a boundary or mixing layer.
This effect is probably caused by a flow pattern behind the anemometers’ mounting rods which is different for different boundary conditions.
The blockage effect was investigated by means of velocity field measurement upstream three types of large size anemometers (2 vane anemometers and 1 cup anemometer) in four wind tunnels of different dimensions and types and by comparison to a calibration in a very large wind tunnel with negligible blockage effect.
Findings on optimal LDA positioning were obtained which can be used as a guidance for mitigation of the blockage effect for all wind tunnels and anemometers with similar construction, geometry, and dimensions as used in this project.
Also, conclusions on wind tunnel size which is large enough for particular anemometer types were drawn.
Progress Report 2026-02-26
The draft of the final report has been circulated among the participants. Comments are collected.
Progress Report 2025-02-28
Measurements are planned to be finished till March 2025.
Data evaluation and final report should be completed till June 2025.
Czech Hydrometeorological Institute (Czechia) does no longer participate in this project.
Progress Report 2024-03-06
Measurements are planned to be finished till May 2024. Data evaluation should be completed till the end of 2024.
Progress Report 2023-03-08
The tests started in August 2022 and are running according to the technical protocol.
A delay up to 2 months might occur due to long time needed for the tests in the initial stage of the project.