Oscillatory flow in jet pumps: nonlinear effects and minor losses

Area of Science:

• Fluid dynamics
• Acoustics
• Mechanical engineering

Background:

• Jet pumps are crucial for fluid handling.
• Understanding nonlinear oscillatory flow is vital for efficient pump design.
• Minor losses significantly impact system performance.

Purpose of the Study:

• To investigate the behavior of tapered cylindrical flow constrictions (jet pumps) under nonlinear oscillatory flow conditions.
• To determine minor loss coefficients for jet pumps with varying inlet curvature radii and taper angles.
• To compare steady and oscillatory flow minor loss coefficients and validate the Iguchi hypothesis.

Main Methods:

• Utilized a nonresonant, lumped-element technique to study jet pump behavior.
• Measured the rectified steady pressure component and acoustic impedance across the jet pump.
• Systematically varied inlet curvature radii and taper angles of the jet pump samples.

Main Results:

• Minor loss coefficients were found to be largely insensitive to geometric variations, except for sharp edges.
• Inflow minor loss coefficients increased with taper angle for a fixed radius of curvature.
• Outflow minor loss coefficients remained relatively constant across different taper angles.
• Steady flow minor loss coefficients showed good agreement with their oscillatory flow counterparts.

Conclusions:

• The study confirms the Iguchi hypothesis by demonstrating good agreement between steady and oscillatory flow minor loss coefficients.
• Geometric parameters like curvature radius and taper angle have predictable effects on jet pump performance in oscillatory flow.
• The findings provide valuable insights for designing and optimizing jet pumps operating in nonlinear oscillatory flow regimes.