Dear all
I want to fabricate the model by scale 1:100 and perform some wind tunnel tests to measure the velocity and pressure distribution on the model. Would you please guide me which scale would be the best according to the wind tunnel blockage effect on the model? please give me the scale rather than the dimensions, to make it easy to select specific tunnel.
Sincerely yours
Mahdi
I would suggest that for civil engineering applications you target a model scale within the range 1:200 to 1:600.
The document 'Wind Tunnel Testing for Buildings and Other StructuresWind Tunnel Testing for Buildings and Other Structures' can provide further details so check it if you can.
Actually I could not find any helpful points in that standard.
there is a rule which says for Blockage effect correction, the Projected area of model should be less than 5% of area of test section
Am/AW
If I want to make a prototype for wind tunnel testing, I will first follow the wind tunnel manual suggestions to find out how big or small my prototype could be (as you have mentioned the less than 5% value for the area model) compared with the test section of the wind tunnel. The next step would be employing dimensional and similarity analysis such as employing dimensionless parameters (Re, Eu, We) and Compressibility parameters (Ma); and choosing the appropriate similarity (Geometric/Kinematic/Dynamic).
I suggest to see AGARDograph 109, "Subsonic wind tunnel wall corrections" due to HC Garner, EWE Rogers, WEA Acum and EC Maskell, published in Oct. 1966, which contains all types of wind tunnel wall effects. You can obtain it through internet.
Dear Dr. M. Adil Yükselen
Thank you for helpful suggestion. Also I had read "Low-Speed Wind Tunnel Testing, 3rd Edition" By Jewel B. Barlow, William H. Rae, Alan Pope which is very helpful.
THe 5% physical scale is generally, to avoid too much error. Actually any cross section blockage (CSA model/CSA tunnel) of up to 10%, would allow corrections which are regarded as accurate. Anything above 10% would mean corrections to the results could be difficult to justify - meaning whatever readings you have cannot be guaranteed of their correctness, especially if you want to measure velocity and pressure.
You also have to understand where the errors are coming from. Understanding this would mean you would be able to handle the correction process easier.
Wan Zaidi
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