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To study the blockage effects in wind tunnel tests for tall buildings with surrounding buildings and establish a reasonable calculation method for the blockage ratio, this paper carried out fifty-one test conditions of pressure model wind tunnel tests with three scale ratios. The tests considered the relative location, relative height, and model nu...
Contexts in source publication
Context 1
... fact, this influence coefficient of the blockage effect is exactly the same as the results of Maskell [2], whose resulting influence coefficient was also 2.5. Figure 8 shows the fitting result of Equation (9). [14,16,17,20,21]. ...
Context 2
... fact, this influence coefficient of the blockage effect is exactly the same as the results of Maskell [2], whose resulting influence coefficient was also 2.5. Figure 8 shows the fitting result of Equation (9). The above analysis indicates that the drag coefficient is affected by both the Reynolds number effect and blockage effect, but compared with the blockage effect, the influence of Reynolds number difference can be ignored. ...
Context 3
... fact, this influence coefficient of the blockage effect is exactly the same as the results of Maskell [2], whose resulting influence coefficient was also 2.5. Figure 8 shows the fitting result of Equation (9). pressure-measuring model; Rt represents the blockage ratio of the target pressure-measuring model; k is the influence coefficient of the blockage effect, which is equal to the drag coefficient error caused by the unit blockage ratio. ...
Context 4
... fact, this influence coefficient of the blockage effect is exactly the same as the results of Maskell [2], whose resulting influence coefficient was also 2.5. Figure 8 shows the fitting result of Equation (9). It should be noted that some studies have indicated that the blockage effect and blockage ratio are not linear, and this phenomenon could also be observed in Figure 8. ...
Context 5
... fact, this influence coefficient of the blockage effect is exactly the same as the results of Maskell [2], whose resulting influence coefficient was also 2.5. Figure 8 shows the fitting result of Equation (9). It should be noted that some studies have indicated that the blockage effect and blockage ratio are not linear, and this phenomenon could also be observed in Figure 8. Even so, when the blockage ratio of the target pressure-measuring model was less than 6%, the relationship between the drag coefficient and the blockage ratio can essentially be linear. ...
Context 6
... results were substantially different from the existing study results of the blockage effect of the single model. It should be noted that some studies have indicated that the blockage effect and blockage ratio are not linear, and this phenomenon could also be observed in Figure 8. Even so, when the blockage ratio of the target pressure-measuring model was less than 6%, the relationship between the drag coefficient and the blockage ratio can essentially be linear. ...
Citations
... While in the drone or UAV model study, an actual size model is normally used. The blockage ratio effect of a small test section can cause serious distortion of the test data [28]. The purpose of this work is to design and build a lowcost wind tunnel with a large test section that is suitable for micro wind turbines, UAVs, drones, etc. testing purposes. ...
... According to [33], a blockage ratio below 10% is acceptable for the wind tunnel test. If the ratio is higher than the acceptable range, a blockage correction needs to be taken into account [34] or it will cause serious distortion in the test data [28]. The test section is designed with transparent walls to observe the test unit during testing. ...
The technological advancement in drones, unmanned aerial vehicles (UAV), wind turbines, and airfoil research has grown rapidly since last decade. Computational fluid dynamics (CFD) analysis is commonly used to study the airflow around a body. Yet, the wind tunnel is an essential instrument in aerodynamic research; however, a commercial wind tunnel normally comes with a small test section and incurs high investment costs. This paper presents the development of a low-cost subsonic open-loop wind tunnel for research and education purposes. The suction-type wind tunnel is intentionally designed with a large test section of 1 m2 and in modular form where each section can be rectified according to the application and for different wind tunnel parameter studies. The detailed design steps, fabrication method, and build of the tunnel are described, along with the flow analysis that has been conducted. Furthermore, a 3D CFD simulation has been performed to simulate the flow condition of the wind tunnel where a good agreement between the simulation and flow measurement is observed. The potential root cause for discrepancy and comparisons with other wind tunnels are discussed. From the preliminary test, wind flow velocity and the turbulence intensity (TI) obtained from the flow measurement are 5.16 m/s and 3.14 % respectively. The TI is less than < 5%, which is considered a medium turbulence case that is good to study the flow around small-scale specimens like micro wind turbines and UAVs.
