抄録
This paper presents experimental and numerical investigations of pulsating flow from an exhaust manifold of an automobile engine. Pulsating exhaust with 1500 rpm flows in S-shaped duct with a square cross section. Thus, velocity fields at first and second bends in a horizontal plane are measured using PIV. It shows that fast flow and slowdown appear around inner and outer walls in both bends, respectively. Numerical simulations using RNG k-e model are in good agreement with measurements. Simulations have also displayed secondary flows grow after passing through the first bend like steady flows, because of pressure gradient and centrifugal force by the duct curvature. However, it is also found that flow direction of the secondary flow at the second bend outlet is opposite to centrifugal force; this result is different from researches of the past. Influences of the intensity of the secondary flows between two bend inlets on flow field are discussed in the present paper.
