This is burner which is being analysed by a four year engineering student at Queens U. Preliminary flow measurements show a primary inlet velocity of about 0.2 to 0.3 metres per second regardless of the height of the optional chimney. Without the chimney, the secondary air inlet velocity was about 0.42m/s. With 30cm of chimney, 0.66m/s. With 60cm of chimney, 1.2m/s. Its great to have numbers. I look forward to more.
The Pressure diagram on the left is an effort to represent the relative static presures at all points vertically. It is just a guess.