CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese Patent Application Number 2020-051196 filed on Mar. 23, 2020. The entire contents of the above-identified application are hereby incorporated by reference.

TECHNICAL FIELD

The disclosure relates to a ducted fan and an aircraft.

RELATED ART

In recent years, development of the electric aircraft has been actively underway in conjunction with improvements in the performance of power electronics, and one development thereof is a vertical take-off and landing (VTOL) type aircraft.

Electric VTOL aircraft feature different types of airframes depending on requirements such as cruise speed, cruise range, and payload. For example, when a fast cruise speed and a long cruise range are required, a tilt wing aircraft provided with a main wing or a tilt rotor aircraft is often employed.

On the other hand, when the main wing or the rotor is tilted (inclined), stable flight control becomes difficult, and therefore, when the cruise speed is slow and the cruise range is short, a fixed rotor aircraft is often employed.

In recent years, there has been an increase in the need for long distance transport and, in the future, conceivably there will be an increase in the need for a tilt wing aircraft or tilt rotor aircraft based on a dispersion fan that takes advantage of electrification. In this case, in consideration of noise, thrust force during hovering, and the like, it is desirable to employ a ducted fan (a fan with a cowl).

In a ducted fan, separation of air near an opening of the cowl where air is introduced (particularly a lip portion) greatly affects the performance of the thrust force. In particular, separation is likely to occur at the lip portion when air flows obliquely relative to a rotational axis of the fan, such as in a transition mode from takeoff to cruising flight or when there is a crosswind. Therefore, how to suppress separation at the lip portion is an important issue.

US 2010/0140416 A discloses a configuration in which a jet is blown to separate a natural flow from the lip portion, and the separation is controlled by controlling the blowing of the jet.

SUMMARY

Nevertheless, in the configuration US 2010/0140416 A, even when separation at the lip portion can be promoted, separation cannot be proactively suppressed.

In light of the foregoing, an object of the disclosure is to provide a ducted fan and an aircraft capable of drawing air about to be separated to a lip portion to suppress separation of the air at the lip portion.

In order to solve the above-described problem, a ducted fan and aircraft of the disclosure adopt the following means.

That is, a ducted fan according to an aspect of the disclosure includes a fan configured to rotate about an axial line to generate a flow of air, and a cowl having a cylindrical shape extending in an axial line direction and surrounding the fan about the axial line, and including an introduction port configured to introduce air from a first end portion side by rotation of the fan. The fan includes a compressor blade provided on an outer circumferential side and a thrust blade provided on an inner circumferential side of the compressor blade. The cowl includes a housing portion configured to accommodate the compressor blade in an interior thereof, an outlet configured to allow air flowing through the housing portion to be blown therethrough by the compressor blade, and an inlet configured to suck air blown out from the outlet. The outlet is provided inwards in a radial direction of the cowl and near the introduction port of the cowl, and the inlet is provided inwards in the radial direction of the cowl and between the outlet and the compressor blade in the axial line direction.

Further, an aircraft according to an aspect of the disclosure includes the above-described ducted fan.

According to a ducted fan and an aircraft according to the disclosure, it is possible to draw air about to be separated to a lip portion to suppress separation of the air at the lip portion.

