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Re: [EnergyPlus_Support] Re: temperature gradient
Neslihan:
No, it is not as simple as you mentioned. The model calculates wind pressure
first based on wind speed and wind pressure coefficient. Engineering
Reference has a section to provide detailed information on page 386. If you
use a crack component, the airflow across the component is flow coefficient
* (Pressure difference)^(flow exponent). Therefore, you have to know indoor
and outdoor pressures also. If you the AirflowNetwork:Multizone:Component
Detailed Opening, the equations used in calculations are provided in the
Engineering Reference on page 383.
Lixing
----- Original Message -----
From: "neslihan turkmenoglu" <neslihanturkmenoglu@xxxxxxxxx>
To: <EnergyPlus_Support@xxxxxxxxxxxxxxx>
Sent: Thursday, April 17, 2008 4:35 AM
Subject: Re: [EnergyPlus_Support] Re: temperature gradient
> hi Lixing
> I wanted to make a simple calculation to see if get
> the same results in Energyplus.
> As I said the measurements were made with specific
> intervals. I found the areas of these intervals and
> multiplied by measured velocities. I found the total
> by adding all these. At last I divided this value to
> total area in order to get mean velocity.
> When I multiply mean velocity with window open area I
> get volume flow rate. Is it wrong?
>
>
> --- Lixing Gu <gu@xxxxxxxxxxxx> wrote:
>
>> Neslihan:
>>
>> My answers are below your questions.
>>
>> ----- Original Message -----
>> From: "neslihanturkmenoglu"
>> <neslihanturkmenoglu@xxxxxxxxx>
>> To: <EnergyPlus_Support@xxxxxxxxxxxxxxx>
>> Sent: Wednesday, April 16, 2008 6:23 AM
>> Subject: [EnergyPlus_Support] Re: temperature
>> gradient
>>
>>
>> > Hi Lixing
>> >
>> >
>> > I calculated wind speed profile exponent with the
>> values got from
>> > wind tunnel measurements in front of the scale
>> model.
>> > In order to understand, I change the values one
>> by one in weather
>> > station object or site atmospheric variation
>> object, nothing changed
>> > in the results of airflow volume flow rate 2 to 1.
>> > The only change occured when I enter my wind speed
>> profile exponent
>> > to airflow network-site wind conditions object.
>> >
>> Your observation is correct. The wind speed
>> calculation in the airflow
>> network model is independent of inputs of weather
>> station object and has its
>> own inputs.
>>
>> > I understood that one exponent is for weather site
>> conditions,
>> > the other exponent is for building site
>> conditions.Why is there the
>> > third one with another default value in airflow
>> network site wind
>> > conditions?
>> >
>> The field of Wind velocity profile exponent in the
>> AIRFLOWNETWORK SIMULATION
>> object and the field of Exponent of Wind Velocity
>> Profile in the
>> AIRFLOWNETWORK:MULTIZONE:SITE WIND CONDITIONS object
>> are used for wind speed
>> calculation. Could you let me know which is the
>> third one specifically?
>
>
>
>>
>> > when I compare the results of energyplus with my
>> manually calculated
>> > volume flow rates, they are not the same. So in
>> order to define the
>> > wind tunnel conditions in Energyplus, what do you
>> suggest me to do?
>> >
>>
>> What is your definition of manual calculation
>> results? If you compare your
>> testing results, you have to ensure the input values
>> used in the EnergyPlus
>> match your testing conditions. I have no knowledge
>> of convertion from wind
>> tunnel conditions to EnergyPlus inputs.
>
>
>
>>
>
>
>> > And which velocity should I enter to design object
>> wind velocity
>> > field- u mean calculated from measured data in
>> front of the scale
>> > model or the wind tunnel's 2.5 m/s Gradient
>> velocity %10 Motor
>> > velocity.
>> >
>> When you got the calaculated wind velocity using the
>> scale model, the
>> velocity used in weather data should be at the
>> height consistent with the
>> input value of Reference height for recorded wind
>> data in the AIRFLOWNETWORK
>> SIMULATION object.
>
>>
>> > I hope you answer in a short time.
>> > thank you very much
>> >
>>
>
>
>
>
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