A contra-rotating multi-layer propeller unit for multi-phase flow according to an exemplary embodiment of the present disclosure includes: a shaft part; a front propeller and a rear propeller connected to the shaft part; an air collection part including a predetermined space therein and the shaft part positioned in the internal space; and an air supply pipe configured to supply air into the air collection part, and a rear propeller blade includes a two-phase blade connected to a rear propeller hub, a layer structure of which an inner surface is connected to an end portion of the two-phase blade, and a single-phase blade positioned at a location corresponding to the two-phase blade on an outer surface of the layer structure.

A contra-rotating multi-layer propeller unit for multi-phase flow according to an exemplary embodiment of the present disclosure includes: a shaft part; a front propeller and a rear propeller connected to the shaft part; an air collection part including a predetermined space therein and the shaft part positioned in the internal space; and an air supply pipe configured to supply air into the air collection part, and a rear propeller blade includes a two-phase blade connected to a rear propeller hub, a layer structure of which an inner surface is connected to an end portion of the two-phase blade, and a single-phase blade positioned at a location corresponding to the two-phase blade on an outer surface of the layer structure.

A performance prediction device includes: an actual measured data obtaining unit that obtains actual measured data of a compressor; a test gas physical property correction formula database in which test gas physical property correction formulae are stored; a test parameter calculation unit that calculates test parameters of the compressor; and a test parameter correction unit that selects at least one of the test gas physical property correction formulae from the test gas physical property correction formula database based on types and a mix ratio of gases included in a test gas to be used in the prediction and corrects the test parameters by using the selected test gas physical property correction formula.

A fuel flow control system includes a centrifugal pump, a gas inlet valve, and a control. The centrifugal pump has a fuel inlet, a gas inlet, and an outlet. The gas inlet valve is disposed upstream of the gas inlet and is responsive to valve position commands to move between a closed position, in which inert gas is prevented from flowing into the gas inlet, and a plurality of open positions, in which inert gas may flow into the gas inlet. The control is coupled to the gas inlet valve and is configured to supply the valve position commands to the gas inlet valve to command the gas inlet valve to selectively move to the closed position, such that the centrifugal pump is configured to operate as a fuel pump, or any open position, such that the centrifugal pump is configured to operate as a fuel-gas mixer.

The invention relates to a spiral pump and a device for treating water comprising this spiral pump, and associated method. The spiral pump comprises: a housing provided with an inlet for water; and a pump body which is accommodated in the housing and rotatable around an axis, wherein the pump body comprises at least one spiral channel, wherein a first outer end of the at least one spiral channel is located on an outer side of the pump body and forms an entrance opening for alternately taking in water and air through rotation of the pump body in the housing, and a second outer end of the at least one spiral channel debouches into an outlet close to the axis, wherein the housing is embodied as pressure chamber and wherein the at least one channel is provided with an increasing diameter from the entrance openings in the direction of the axis.