The paper presents comprehensive experimental and numerical studies on water flow through rectangular
S-shaped diffusers. The experimental setup was designed and constructed to perform the measurements
which have been carried out on twelve models of S-shaped diffusers. The measurements of pressure
distributions along the outer and inner walls of the S-shaped diffuser were performed for different
parameters including area ratios, curvature ratios, inflow Reynolds numbers, turning angles (45◦
/45◦
,
60◦
/60◦
, 90◦
/90◦
), and flow paths (45◦
/45◦
, 60◦
/30◦
, 30◦
/60◦
). The energy-loss coefficients for each model are
based on detailed measurements of the wall pressure distributions along walls of the S-shaped -diffuser
models including long upstream and downstream tangents. The energy-loss coefficient data were plotted as
a function of Reynolds number for the tested models at different geometrical parameters. The experimental
data for different S-diffuser configurations have been used for assessing credibility of the numerical code
using different turbulence models. High performances of computations with turbulence closure provided by
the standard k-ε model have been carried out for prediction of the performance of S-diffusers at different
inflow and geometrical conditions. The results showed that the diffuser energy-loss coefficient is strongly
affected by the geometrical parameters of S-shaped diffuser and inflow Reynolds number. Increasing area
ratio, curvature ratio, and inflow Reynolds number increase the diffuser performance. The turning angle
plays an important role in improving the S-shaped diffuser performance. But, the diffuser performance
decreases, when the turning angle is larger than 60° and the flow path changes far than the symmetric path
(45°/45°).