Fanger / ISO 7730 / ASHRAE 55
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To simulate the 3D detailed flow and thermal behavior of HVAC system, we develop a dedicated simulation software for non CFD expert. Learn more..
Enter air temperature (°C), mean air velocity (m/s), and turbulence intensity (%)
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To simulate the 3D detailed flow and thermal behavior of HVAC system, we develop a dedicated simulation software for non CFD expert. Learn more..
Units: W, kW, MW, BTU/h, kBTU/h, ton (TR), hp (mechanical)
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To simulate the 3D detailed flow and thermal behavior of HVAC system, we develop a dedicated simulation software for non CFD expert. Learn more..
Units: m/s, ft/s, ft/min (FPM), m/min, km/h, mph
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To simulate the 3D detailed flow and thermal behavior of HVAC system, we develop a dedicated simulation software for non CFD expert. Learn more..
Units: J, kJ, MJ, Wh, kWh, MWh, BTU, kBTU, therm (US), kcal(IT), ton-hour (TR·h)
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To simulate the 3D detailed flow and thermal behavior of HVAC system, we develop a dedicated simulation software for non CFD expert. Learn more..
Units: CFM, CFS, L/s, L/min, m³/h, m³/s
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To simulate the 3D detailed flow and thermal behavior of HVAC system, we develop a dedicated simulation software for non CFD expert. Learn more..
To simulate the 3D detailed flow and thermal behavior of HVAC system, we develop a dedicated simulation software for non CFD expert. Learn more..
The angle of attack is the angle between the oncoming airflow and the chord line of the wing or airfoil.
Generally, we can see the angle of attack as shown in Image 1 if we assume the flight path is perpendicular to the direction of gravity. But, for modeling such as Computational Fluid Dynamics, it is easier to change the angle of attack instead of rotating the geometry (as shown in Image 2), by converting the velocity components:
u = U*cos(AoA)
v = U*sin(AoA)
With the u and v are the velocity components in the x and y directions respectively, and U is the magnitude of the velocity.
so we must calculate the Lift and Drag based on the calculated forces (for example Fx and Fy) with the equations:
Lift = Fy*cos(AoA) – Fx*sin(AoA)
Drag = Fx.cos(A0A) + Fy*sin(A0A)
Determining appropriate time steps for a CFD simulation involving rotating blades is crucial for achieving accurate and stable results. In this calculator, we will use typical scenario for a rotating blade (fan, turbine, blower, etc) with specific rotational speed, blade numbers, and desired iteration input to determine the timestep required and total number of iterations.
To determine the timesteps, we must first determine the time required for the system to achieve a complete single rotation, or its frequency:
frequency = time/rotation = 1/rotational speed [Hz]
The rotational speed must be in rev/s, if you have the rpm data, just divide the rpm by 60 to get rev/s.
Then, calculate time required for one blade achieve the next blade location, which can be calculated by dividing the frequency by the number of blade:
blade-to-blade time = frequency/number of blade [s]
This value is the “maximum” time step that you might apply to your simulation. By inputing this value, you cannot capture the blade motion within the simulation. Then, we must specify the number of motion (in the animation) for blade to achieve its next position. You also must consider the number of autosave for your setup, the “appeared” timestep in your post processing will be your inputed timestep times the autosave/timestep, which ultimatelly can be calculated as follows:
time step = blade-to-blade time/(blade-to-blade motion*autosave) [s]
After you have your time-step value, you can calculate the total number of iteration based on your total desired revolution, internal iteration (iteration per number of motion) and your timetep as follows:
end time = frequency*total rotation [s]
total iteration = (end time/timestep)*internal iteration [iterations]
These equations illustrated in the Image below (3 motions blade-to-blade):
