Analytical mathematical modeling of the torque caused by the laundry

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Discussion Overview

The discussion revolves around modeling the torque required to rotate a washing machine drum during the washing process. Participants explore various factors affecting torque, including the dynamics of water and clothing inside the drum, and the energy consumption of the motor. The scope includes theoretical modeling, experimental considerations, and practical estimates related to washing machine operation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant seeks help with modeling torque based on target velocity and the dynamics of water and clothing inside the drum.
  • Another participant highlights the complexities of the problem, including interactions between clothes and water, suggesting that experimental methods may be necessary.
  • A participant provides an estimate for energy consumption in a front-loading washing machine, calculating power requirements based on the lifting of wet clothes.
  • There is a discussion about the type of washing machine being analyzed, specifically whether it is a top loader or a front loader, which may influence the modeling approach.
  • One participant expresses a need for mathematical relations and literature to support their master's thesis work on this topic.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility of experimental methods versus theoretical modeling. While some provide estimates and calculations, others emphasize the complexities and real-world factors that complicate the modeling process. No consensus is reached on a definitive approach to the problem.

Contextual Notes

Participants acknowledge limitations in their models, including the dependence on assumptions about the behavior of water and clothing, the impact of drum design, and the need for further literature to support their claims.

OussamaSscn
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TL;DR
analytical mathematical modelling of the torque caused by the laundry and water in a washing machine drum
Hello my dear physicists,
I'm trying to model the varied generated (needed)Torque to rotate a washing machine Drum during a Washing Process
so i assumed that the Model has as Input the target vilocity and as an Output the new needed torque to rotate the Drum(to be as a input for the motor model), depending on what is happening inside the drum.
The main final Goal is to simulate the consumed Power by the motor
My questions are :
1)If anyone can help me about this Topic with recommended Documents, ideas ..etc i will be very thankfull
2)inside the Drum there is Water, causing a Torque, I think depending on the water density and the friction with the inner wall of the Drum. so how can I calculte the Torque caused by the Water ?
3)during the Washing process, the Target Speed is relative low (about 45rpm) which makes the clothing lifted up to certain angle and then falling down. I could calculate the limit angle of lifting and the"flight"time and the landing angle of the clothing assuming that the clothing is a one point mass , how can I generalize this equations on a continium of Mass of clothing occupying a certain Volume of the Drum depending on its density and friction properties ? how can i calculate the Torque caused by this Motion ? (I'm not asking for an exact solution, but any idea or notice what could help)
3)during spinning process the clothing still attached on the inner wall of the drum but with random distribution causing an unbalanced Load and a uniformily distributed Load, so how can I determine the Torque in this case ?
Attached is a picture explaining a little bit
 

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There is a lot of real-world complications in this problem. The impact of the "beaters" with clothes, the relationship between the water and the clothes, the rapidity of the change of direction and speed of the spin, etc. I am afraid that the only realistic way to proceed is experimental.
 
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@OussamaSscn
Welcome to PF.
Are you analysing a top loader with a central agitator, or a water efficient front loaded machine ?
 
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Here is my estimate for a front loading (new-fangled) machine.
  1. The energy is almost all consumed by continuously lifting the soaking wet clothes and there is no recovery of energy from their subsequent fall.
  2. Assuming all of the wet clothes are lifted 0.5m per rev at 1 rev /sec then this consumes 5 watts lifting each kg of wet clothes in the drum
  3. The drum contains ~30l of water (almost all absorbed into clothes repeatedly ) so when running the motor must supply 150 W of useable mechanical power at 1rps.
  4. I believe this estimate is consistent with the size (1/3-1/2 HP) motors seen in these units
So maybe the estimate is not so complicated (I really didn't "cheat")!
 
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FactChecker said:
There is a lot of real-world complications in this problem. The impact of the "beaters" with clothes, the relationship between the water and the clothes, the rapidity of the change of direction and speed of the spin, etc. I am afraid that the only realistic way to proceed is experimental.
Thank you for replying,
Experimental is unfortunately not an option,
 
Baluncore said:
@OussamaSscn
Welcome to PF.
Are you analysing a top loader with a central agitator, or a water efficient front loaded machine ?
Hallo and thank you for replying,
It is a front loaded machine
Three lifters are on the inner wall of the drum
 
hutchphd said:
Here is my estimate for a front loading (new-fangled) machine.
  1. The energy is almost all consumed by continuously lifting the soaking wet clothes and there is no recovery of energy from their subsequent fall.
  2. Assuming all of the wet clothes are lifted 0.5m per rev at 1 rev /sec then this consumes 5 watts lifting each kg of wet clothes in the drum
  3. The drum contains ~30l of water (almost all absorbed into clothes repeatedly ) so when running the motor must supply 150 W of useable mechanical power at 1rps.
  4. I believe this estimate is consistent with the size (1/3-1/2 HP) motors seen in these units
So maybe the estimate is not so complicated (I really didn't "cheat")!
Thank you for replying,
Your Answer is very helpful
Im doing a Master thesis so that's why i have to describe it with mathematical relations
So if you could help me with mentioning any literature i will be very grateful
 

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