Analytic derivation of static pressure distribution in fully developed helical flows

An approximate expression for the distribution of static pressure in a test cross section for an annular axial flow of air with inner cylinder rotation is derived using only measured values of the outer-wall static pressure, the total pressure in the test section, and the flow angle of the total velocity vector. A closed-form solution is obtained by numerical integration of the final expression. Computed static-pressure profiles are plotted, and the results are shown to be very consistent.