1. Flow calculations Åke Mälhammar Frigus Primore malhammar.ake@wanadoo.fr 1 Flow calculations Dynamic pressure Dynamic pressure Pressure drop Pressure drop Bernoulli's equation Bernoulli's equation Fan curves Fan curves

2. Bernoulli's equation 1 2 Bernoulli's equation Dynamic pressure Total pressure

3. Bernoulli's equation 2 3

4. Pressure losses 4Friction Head loss Friction (laminar, circular pipes) (turbulent, circular pipes) Head loss

5. Expansion 5 A1A1 A2A2   <15 o

6. Contracting jets 6 A 1, w 1 A2A2 A 3, w 3

7. Fan curves 7 Fan curve System curve Pressure Flow

8. Electronic devices 8 Head loss

9. Flow distribution 1 9 pp pp Friction only Dynamic only Path Z-path U-path

10. Flow distribution 2 10 D D Uniform distribution but risk for recirculation of outlet into inlet Risk for non uniform distribution. Make sure D is sufficiently large.

11. Flow distribution 3 11 Risk for non uniform distribution. D Add a honey comb structure, a dense net or increase the measure D.