Gedeon streaming is known to considerably deteriorate the thermal efficiency of a traveling-wave thermoacoustic engine with looped configuration. The time-average pressure drop induced by a jet pump can efficiently suppress the Gedeon streaming. In this study, such suppression mechanism of the jet pump is investigated, and the emphasis is put on the effects of the dimensionless rounding, the taper angle, and the cross-sectional area ratio. An experimental apparatus has been set up to measure the time-averaged pressure drop induced by the jet pumps in oscillatory flow. Controlled experiments and characterization reveal the time-averaged pressure drop and working efficiency increase with a rise in dimensionless rounding when it is less than 0.15. For jet pumps with the fixed opening areas, the taper angle in the range from 3° to 9° is capable of producing a larger time-averaged pressure drop with a higher working efficiency, and the change of taper angle has little effect on the performance. However, performance degradation is observed as the taper angle increases beyond 9°. Moreover, when the taper angle ranges from 3° to 9°, the time-averaged pressure drop and working efficiency can be improved by increasing the cross-sectional area ratio.