Calculation of blockage ratio?

In summary, the conversation discusses the formulation of wind tunnel blockage ratio in relation to an experimental study with an aspect ratio of 5. The blockage ratio is defined as the percentage of the test section blocked by the model and can be found by dividing the frontal area of the model by the cross-section of the tunnel. The book "Low Speed Wind Tunnel Testing" by Pope is recommended for further information on this topic.
  • #1
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Hello, i am asking a question:
is there any formulation of wind tunnel blockage ratio? i will carry out experimental study in a wind tunnel, the aspect ratio (AR)=5, and what equals the blockage ratio?


if someone helps me, i will be very happy :)


thank you...
 
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  • #2
Do you have a copy of "Low Speed Wind Tunnel Testing" by Pope handy? These kinds of questions are covered in detail in that book. At any rate, the blockage ratio is simply the percentage of the test section that is blocked by the model. In other words, the frontal area of your model over the cross-section of the tunnel.
 

1. What is blockage ratio and why is it important in scientific calculations?

Blockage ratio is a measure of how much of a flow field is obstructed by a solid object, such as a building or a vehicle. It is important because it affects the accuracy and reliability of calculations, as well as the performance and safety of the object in question.

2. How is blockage ratio calculated?

Blockage ratio is calculated by dividing the frontal area of the object by the total area of the flow field. For example, if a building has a frontal area of 100 square meters and the flow field has an area of 500 square meters, the blockage ratio would be 0.2 (100/500).

3. What is considered a high or low blockage ratio?

A high blockage ratio is typically anything above 0.2, while a low blockage ratio is below 0.1. However, this can vary depending on the specific application and the desired accuracy of calculations.

4. How does blockage ratio affect fluid flow and pressure?

A higher blockage ratio can cause increased turbulence and flow separation, leading to changes in fluid flow and pressure distribution. This can result in higher drag and lift forces on an object, which can impact its performance and stability.

5. Are there any limitations to using blockage ratio in calculations?

While blockage ratio is an important factor to consider in scientific calculations, it should not be the only factor. Other factors such as Reynolds number, flow conditions, and object shape can also impact the accuracy of calculations. Additionally, blockage ratio may not be applicable in all types of flow situations, such as compressible flow or highly turbulent flow.

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