Non-uniform inflow A questionable assumption which has been made so far is that the induced velocity is uniform across the blade span. The effect of nonuniformity can be allowed for by using differential forms of the appropriate equations in the combination of blade element theory and momentum theory. Equation (3.21) in the blade element theory is replaced by

 Non-uniform inflow

A questionable assumption which has been made so far is that the induced velocity is uniform across the blade span. The effect of nonuniformity can be allowed for by using differential forms of the appropriate equations in the combination of blade element theory and momentum theory. Equation (3.21) in the blade element theory is replaced by  which expresses the element of thrust on an annulus of the disc at radius r. The corresponding equation from momentum theory, again using the hover case for simplicity, is the replacement of Equation (2.2), namely.