Oscillatory flow in jet pumps: nonlinear effects and minor losses.

A nonresonant, lumped-element technique is used to investigate the behavior of tapered cylindrical flow constrictions (jet pumps) in the nonlinear oscillatory flow regime. The array of samples studied spans a wide range of inlet curvature radii and taper angles. By measuring the rectified steady pressure component developed across a jet pump as well as the acoustic impedance, the minor loss coefficients for flow into and out of the narrow end of the jet pump are determined. These coefficients are found to be relatively insensitive to all but the smallest curvature radii (i.e., sharp edges). For fixed radius of curvature, the inflow minor loss coefficient increases with increasing taper angle while the outflow coefficient remains relatively constant. For all of the samples, the steady flow minor loss coefficients are also measured and compared to their oscillatory flow counterparts. The agreement is good, confirming the so-called Iguchi hypothesis.