Problem with wall heat transfer coefficient during drilling

Paul666 · December 11, 2016, 18:15

Hello everyone!

Could you be kind enough to tell me how to make like that? Maybe someone has a tutorial on how to do it?

https://www.youtube.com/watch?v=KslKsdfeWJw

ghorrocks · December 12, 2016, 04:16

The tutorials which come with CFX are a good place to start. Have a look on the ANSYS customer webpage, or the tutorials provided with CFX.

Paul666 · December 12, 2016, 14:47

What am I doing wrong?

My setup is like this:
Air temp = 20*C
Drill temp = 150*C
Drill speed = 1000 rev/min^-1

I have to calculate the heat flow..

https://drive.google.com/open?id=0B7...mlQVDBGbXdqWkE

ghorrocks · December 12, 2016, 16:32

Air pressure = 1000 MPa? Are you sure on that one? Which planet are you running this wind turbine on?

And what has a drill got to do with a wind turbine?

bparrelli · December 12, 2016, 17:47

Is this an oil drill powered by a wind turbine? I can't understand your model.

Paul666 · December 13, 2016, 08:22

haha okej, let's start from the beginning.

I try to give the rotation of the drill in the Z axis at a speed of 8,000 [rev / min ^ -1]. When Defining the speed and the rotation axis shows me of the message:

In Analysis 'Flow Analysis 1' - Domain 'Air: If a solid has motion set and it is connected to a stationary fluid domain, a moving wall velocity boundary condition must be specified on the fluid solid interface.

However, I do not know what exactly it. Any ideas?

ghorrocks · December 13, 2016, 16:31

Quote:

let's start from the beginning

No, that is not the beginning. This model obviously has nothing to do with wind turbines as the title suggests so you better explain what you are modelling, why you are modelling it and what you intend to learn from the model. Please include an image of the geometry you are modelling.

Paul666 · December 14, 2016, 01:51

Sorry for the confusion, please administrator to change the topic to "Problem with wall heat transfer coefficient during drilling"

My job is to:
I must modeled a simplified model of the drill and then calculate the wall heat transfer coefficient during drilling. The Drill bit is rotated at 8,000[rev / min] in Z axis and the initial temperature is 150 ° C. Around the drill is air at a temperature of 25 ° C. I used the function enclosure to determine the area in which they conducted research. I have problem with the giving rotation Drills. I tried to do as above in the pictures. However, not working as it should. I want to use the results also line speed to show how the air behaves around the drills.

ghorrocks · December 14, 2016, 05:22

I have changed the title of the thread. But before we can answer your question we need to know much more about what you are trying to do.

Is the drill just rotating in open air? Or is it in a hole and performing the drilling action?

Do you just want the HTC? Or do you want the cooling curve of the drill? Or are you interested in what the air flow does around the drill?

Are there any other heat sources/sinks acting on the drill? Maybe heat from friction, or a coolant, or just ambient air?

Do you need to know the temperature profile inside the drill?

Paul666 · December 14, 2016, 05:34

Thank you for changing the theard.

1. Yes, the drill is rotated in open air.
2. Yes, I want to see speed lines. As the air flows around the rotating drill.
3. No, there is only ambient air, which has 25 * C
4. No, only on the surface of the drill.

I can insert more screenshots of the module "setup" or send whole file with the program.

ghorrocks · December 14, 2016, 05:41

What are speed lines? Do you mean stream lines?

Can the drill be assumed at constant temperature?

What is the ambient air doing? Does it have a cross flow? Do you expect it to form a buoyant plume?

Paul666 · December 14, 2016, 05:47

1. Yes, I mean stream lines.
2. Yes, we can assume the drill at a constant temperature (150*C)
3. Cross flow

ghorrocks · December 14, 2016, 05:53

OK, almost there. Just a last question:

How strong is the cross flow?

ghorrocks · December 14, 2016, 06:17

While you are answering the cross flow strength question, I can make the following suggestions:

As the drill temperature is known then you do not need to model it. So do not model the drill as a solid body. The drill should be modelled as a rotating frame of reference with the drill being a cavity inside the rotating frame of reference - just like what is commonly done in turbomachinery simulations. Have a look in the CFX tutorials for examples of this.

You can probably model the rotating frame of reference as a frozen rotor. This will mean you can model the drill with a steady state simulation which will dramatically simplify things.

The strength of the cross flow will determine whether buoyancy is necessary or not.

December 11, 2016, 18:15	Problem with wall heat transfer coefficient during drilling	#1
Paul666 New Member Paul Join Date: Dec 2016 Posts: 7 Rep Power: 9	Hello everyone! Could you be kind enough to tell me how to make like that? Maybe someone has a tutorial on how to do it? https://www.youtube.com/watch?v=KslKsdfeWJw

December 12, 2016, 14:47		#3
Paul666 New Member Paul Join Date: Dec 2016 Posts: 7 Rep Power: 9	What am I doing wrong? My setup is like this: Air temp = 20C Drill temp = 150C Drill speed = 1000 rev/min^-1 I have to calculate the heat flow.. https://drive.google.com/open?id=0B7...mlQVDBGbXdqWkE Last edited by Paul666; December 13, 2016 at 07:55.

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December 12, 2016, 04:16		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	The tutorials which come with CFX are a good place to start. Have a look on the ANSYS customer webpage, or the tutorials provided with CFX.

December 12, 2016, 16:32		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	Air pressure = 1000 MPa? Are you sure on that one? Which planet are you running this wind turbine on? And what has a drill got to do with a wind turbine?

December 12, 2016, 17:47		#5
bparrelli Member turbo4life Join Date: Nov 2016 Posts: 41 Rep Power: 9	Is this an oil drill powered by a wind turbine? I can't understand your model.

December 13, 2016, 08:22		#6
Paul666 New Member Paul Join Date: Dec 2016 Posts: 7 Rep Power: 9	haha okej, let's start from the beginning. I try to give the rotation of the drill in the Z axis at a speed of 8,000 [rev / min ^ -1]. When Defining the speed and the rotation axis shows me of the message: In Analysis 'Flow Analysis 1' - Domain 'Air: If a solid has motion set and it is connected to a stationary fluid domain, a moving wall velocity boundary condition must be specified on the fluid solid interface. However, I do not know what exactly it. Any ideas?

December 14, 2016, 01:51		#8
Paul666 New Member Paul Join Date: Dec 2016 Posts: 7 Rep Power: 9	Sorry for the confusion, please administrator to change the topic to "Problem with wall heat transfer coefficient during drilling" My job is to: I must modeled a simplified model of the drill and then calculate the wall heat transfer coefficient during drilling. The Drill bit is rotated at 8,000[rev / min] in Z axis and the initial temperature is 150 ° C. Around the drill is air at a temperature of 25 ° C. I used the function enclosure to determine the area in which they conducted research. I have problem with the giving rotation Drills. I tried to do as above in the pictures. However, not working as it should. I want to use the results also line speed to show how the air behaves around the drills.

December 14, 2016, 05:22		#9
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	I have changed the title of the thread. But before we can answer your question we need to know much more about what you are trying to do. Is the drill just rotating in open air? Or is it in a hole and performing the drilling action? Do you just want the HTC? Or do you want the cooling curve of the drill? Or are you interested in what the air flow does around the drill? Are there any other heat sources/sinks acting on the drill? Maybe heat from friction, or a coolant, or just ambient air? Do you need to know the temperature profile inside the drill?

December 14, 2016, 05:34		#10
Paul666 New Member Paul Join Date: Dec 2016 Posts: 7 Rep Power: 9	Thank you for changing the theard. 1. Yes, the drill is rotated in open air. 2. Yes, I want to see speed lines. As the air flows around the rotating drill. 3. No, there is only ambient air, which has 25 * C 4. No, only on the surface of the drill. I can insert more screenshots of the module "setup" or send whole file with the program.

December 14, 2016, 05:41		#11
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	What are speed lines? Do you mean stream lines? Can the drill be assumed at constant temperature? What is the ambient air doing? Does it have a cross flow? Do you expect it to form a buoyant plume?

December 14, 2016, 05:47		#12
Paul666 New Member Paul Join Date: Dec 2016 Posts: 7 Rep Power: 9	1. Yes, I mean stream lines. 2. Yes, we can assume the drill at a constant temperature (150*C) 3. Cross flow

December 14, 2016, 05:53		#13
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	OK, almost there. Just a last question: How strong is the cross flow?

December 14, 2016, 06:17		#14
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	While you are answering the cross flow strength question, I can make the following suggestions: As the drill temperature is known then you do not need to model it. So do not model the drill as a solid body. The drill should be modelled as a rotating frame of reference with the drill being a cavity inside the rotating frame of reference - just like what is commonly done in turbomachinery simulations. Have a look in the CFX tutorials for examples of this. You can probably model the rotating frame of reference as a frozen rotor. This will mean you can model the drill with a steady state simulation which will dramatically simplify things. The strength of the cross flow will determine whether buoyancy is necessary or not.