Help with torque calculation of underwater rotating disk?

In summary, the conversation discusses a setup consisting of a rotating disk with a diameter of 150mm and thickness of 10mm, attached to a motor and surrounded by water. The disk has a circular ring on its upper surface with a diameter of 80mm and height of 20mm. The weight of the setup is approximately 1kg and the water level remains constant. The conversation also mentions the need for simulations to accurately calculate the torque required for the setup. The individual asking for help has a disk with a radius of 8cm and thickness of 4cm that needs to be rotated at 100rpm, but is unsure of the specifications for a DC motor.
  • #1
IamDev
7
0
Hello Guys,

I have a disk of diameter of 150mm and thickness of 10mm which is rotating at the constant speed of 100rpm. The disk is inside water which is approximately 4-5 cm below the surface. Disk is horizontal (parallel to the water surface). Disk is attached with the shaft of the motor. At the upper surface of the disk there is a circular ring of outside diameter of 80mm and inside diameter of 70mm and height is 20mm.
I need to calculate the torque required to rotate this whole setup at 100rpm.
The weight of this setup is approximately about 1kg and the water is still at the surface.
 
  • #3
In general, those things need simulations to get some numerical estimates. The water level will get influenced by the rotating disk, so you have to consider the water/air boundary as well. There are software packages that can model it, but expect some work to get the simulations running.
 
  • #4
Is it possible to calculate required torque if we consider that water level will be constant during the whole process?
 
  • #5
It is possible to get some estimates, but I think without a simulation all those estimates will be problematic.
 
  • #6
Okay, I have a disk of 8 cm radius and 4 cm thickness and I have to rotate the disk at constant speed of 100 rpm. I need to buy a DC motor to rotate the disk but I am unable to short out the specification of DC motor. Can you help me please?
 
  • #7
Well, it is possible to get some order of magnitude estimate. Do you have a sketch of the setup? How large is the water basin? What is below the disk?
 

Related to Help with torque calculation of underwater rotating disk?

1. How do I calculate the torque of an underwater rotating disk?

To calculate the torque of an underwater rotating disk, you will need to know the angular velocity, the radius of the disk, and the fluid density. Then, you can use the formula T = I * α, where T is the torque, I is the moment of inertia, and α is the angular acceleration. The moment of inertia can be found by multiplying the mass of the disk by the square of its radius.

2. What is the importance of torque calculation in underwater rotating disks?

The torque calculation of underwater rotating disks is important because it helps in understanding the forces acting on the disk and the resulting motion. This information is crucial for designing efficient and stable underwater systems, such as propellers and turbines. It also allows for accurate prediction of the power and speed of these systems.

3. Can the torque of an underwater rotating disk vary?

Yes, the torque of an underwater rotating disk can vary depending on the angular velocity, fluid density, and size of the disk. It can also be affected by external factors such as water currents and friction. Therefore, it is important to consider all these factors when calculating the torque for a specific situation.

4. How does the density of the fluid affect the torque of an underwater rotating disk?

The density of the fluid has a direct impact on the torque of an underwater rotating disk. A denser fluid will result in a higher torque, while a less dense fluid will result in a lower torque. This is because the denser fluid exerts a greater resistance on the disk, resulting in a higher force and thus a higher torque.

5. Are there any limitations to calculating the torque of an underwater rotating disk?

While the torque calculation for an underwater rotating disk can provide valuable information, there are some limitations to consider. For instance, the calculation does not take into account factors such as turbulence and vortex shedding, which can significantly affect the torque. Additionally, the calculation assumes a perfectly round and evenly distributed disk, which may not always be the case in real-world scenarios.

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