# Pressure in Wind Tunnel Test Section

• Sunny1261
In summary: Expert SummarizerIn summary, the question is about calculating the velocity and total pressure in a one-circuit wind tunnel with a given inlet to throat ratio and pressure difference. The student has made progress using Bernoulli's equation and the equation of continuity, but is stuck on solving for the total pressure. The expert suggests using the concept of total pressure recovery to solve the rest of the problem.
Sunny1261
Hello Everyone,
I have a fairly simple wind tunnel question but I cannot seem to connect the pieces.

## Homework Statement

Consider a low speed one-circuit wind tunnel with an inlet to throat ratio of 12. The pressure difference between the inlet and the test section was measured to be 10 centimeters of mercury on a U-tube mercury manometer. Calculate the velocity in the tunnel test section. Also, compute the total pressure in the test section.

## Homework Equations

What is the pressure?

## The Attempt at a Solution

With the aid of Bernoulli's equation and equation of continuity, I was able to determine the velocity in the test area to be 147 m/s. With the equation of continuity, the velocity in the settling chamber is 12.25 m/s.

Using this, I'm able to solve about 1/2 of Bernoulli's equation, but I am still left with two pressure terms, and therefore, am unable to solve for the total pressure in the test section.

Thanks.

A hint would be much appreciated,
Sunny

Dear Sunny,

Thank you for sharing your question with the forum. It seems like you have made some good progress in solving for the velocity in the test section using Bernoulli's equation and the equation of continuity. However, as you mentioned, there are still two pressure terms left to solve for the total pressure in the test section.

To solve for the total pressure, you can use the concept of total pressure recovery. In a one-circuit wind tunnel, the total pressure at the inlet should be equal to the total pressure at the test section. This means that the total pressure in the test section can be calculated by adding the measured pressure difference (10 cm of mercury) to the total pressure at the inlet.

I hope this helps you solve the rest of the problem. Keep up the good work in your scientific studies!

## 1. What is the purpose of measuring pressure in a wind tunnel test section?

The purpose of measuring pressure in a wind tunnel test section is to understand the aerodynamic forces and pressure distribution on a model or object in different airflow conditions. This helps in evaluating the performance and design of the model, and can also be used for research and development purposes.

## 2. How is pressure measured in a wind tunnel test section?

Pressure is typically measured using pressure sensors such as pitot tubes, pressure transducers, or pressure-sensitive paint. These sensors are strategically placed in the test section to capture the pressure at different points on the model or object being tested.

## 3. What is the relationship between airspeed and pressure in a wind tunnel test section?

In a wind tunnel, as the airspeed increases, the pressure decreases. This is due to the Bernoulli's principle, which states that as the speed of a fluid increases, its pressure decreases. This relationship is important in understanding the aerodynamics of an object and how it responds to different airspeeds.

## 4. How does the shape of the test section affect pressure measurements in a wind tunnel?

The shape of the test section can affect pressure measurements in a wind tunnel as it can cause flow disturbances and affect the accuracy of the measurements. It is important to have a streamlined and well-designed test section to minimize these disturbances and obtain accurate pressure readings.

## 5. What are some factors that can cause errors in pressure measurements in a wind tunnel test section?

Some factors that can cause errors in pressure measurements in a wind tunnel test section include turbulence, blockage effects, and calibration errors in the pressure sensors. The design and construction of the wind tunnel, as well as the proper placement and calibration of the pressure sensors, are crucial in minimizing these errors.

Replies
4
Views
3K
Replies
6
Views
4K
Replies
9
Views
2K
Replies
19
Views
2K
Replies
3
Views
2K
Replies
12
Views
664
Replies
1
Views
1K
Replies
3
Views
2K
Replies
18
Views
3K
Replies
3
Views
1K