Static or dynamic pressures in duct

In summary, the conversation discusses the relationship between dynamic pressure and airflow in a duct with static and total pressure probes. The participant suggests that a high dynamic pressure will maximize airflow through the duct. However, without a clearer explanation or visual aid, the overall question remains unanswered. Additional help is requested from another member.
  • #1
Jonny6001
20
0
Hello, I have a little question regarding airflow.

You have an object in a wind-tunnel, which has a dynamic pressure of 1000Pa and say static pressure of 99000Pa.

If the object has a duct with static and total pressure probes, to maximise airflow through that duct, would you be looking for the highest or lowest dynamic pressure?

The way I approach it is, if the dynamic pressure is high the it will cause low static pressure which has the effect of trying to "suck" air though the duct. So a high dynamic pressure in the duct will maximize airflow. Do you guys agree with this?

Just as an aside, the duct is not exactly in-line with the air flow direction.
 
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  • #3
anorlunda said:
ping @Chestermiller . Help needed, spring cleaning.
Sorry. I really don't understand what this member is asking. Maybe @boneh3ad can help.
 
  • #4
1) This is from February 2010, so... um...

2) This is incredibly hard to parse without some kind of drawing or at least a better written description.

3) The short answer is that for any duct, for a given total pressure, incompressible air flow will be maximized when you raise the dynamic pressure because, literally, that amounts to raising the velocity of the flow. I have no idea how this relates to the broader question.
 
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What is the difference between static and dynamic pressures in duct?

Static pressure refers to the pressure exerted by a fluid on the walls of a duct when the fluid is not in motion. Dynamic pressure, on the other hand, is the pressure caused by the fluid's motion. In ducts, static pressure is typically used to measure the resistance to airflow, while dynamic pressure is used to measure the velocity of the fluid.

How do you measure static and dynamic pressures in duct?

Static pressure can be measured using a manometer, which consists of a U-shaped tube filled with a liquid. The height difference between the two sides of the tube indicates the static pressure. Dynamic pressure can be measured using a pitot tube, which has a small opening facing the airflow. The pressure difference between the opening and the sides of the tube represents the dynamic pressure.

What factors affect static and dynamic pressures in duct?

Static pressure is mainly affected by the shape and size of the duct, as well as any obstructions or bends in the duct. Dynamic pressure, on the other hand, is influenced by the velocity of the fluid, which is affected by factors such as the fluid's density and the shape of the duct.

How do static and dynamic pressures affect airflow in duct?

Both static and dynamic pressures play a significant role in determining the airflow in ducts. Higher static pressure indicates greater resistance to airflow, while higher dynamic pressure indicates faster airflow. These pressures can be manipulated to control the direction and speed of airflow in duct systems.

What are the practical applications of understanding static and dynamic pressures in duct?

Understanding static and dynamic pressures in duct is crucial in designing efficient duct systems for heating, ventilation, and air conditioning (HVAC) systems. It can also be used in industries such as aerospace and automotive engineering to optimize the airflow in ducts for better performance and fuel efficiency.

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