Abstract: A flow control method is a flow control method of controlling flow around a blade of a rotary wing, a plasma actuator being disposed at the blade. The flow control method includes: determining a characteristic frequency ratio that is a characteristic value among frequency ratios, each of the frequency ratios being a ratio between an actuator driving frequency and an angle of attack changing frequency, the actuator driving frequency being a frequency of an applied voltage applied to the plasma actuator, the angle of attack changing frequency being a frequency at which an angle of attack of the blade changes in accordance with a rotation angle of the blade; setting the actuator driving frequency such that the frequency ratio becomes the characteristic frequency ratio; and applying a voltage of the set actuator driving frequency to the plasma actuator to control the flow around the blade.

Abstract: A flow control method is a flow control method of controlling flow around a blade of a rotary wing, a plasma actuator being disposed at the blade. The flow control method includes: determining a characteristic frequency ratio that is a characteristic value among frequency ratios, each of the frequency ratios being a ratio between an actuator driving frequency and an angle of attack changing frequency, the actuator driving frequency being a frequency of an applied voltage applied to the plasma actuator, the angle of attack changing frequency being a frequency at which an angle of attack of the blade changes in accordance with a rotation angle of the blade; setting the actuator driving frequency such that the frequency ratio becomes the characteristic frequency ratio; and applying a voltage of the set actuator driving frequency to the plasma actuator to control the flow around the blade.

Abstract: A flow control method is a flow control method of controlling flow around a blade of a rotary wing, a plasma actuator being disposed at the blade. The flow control method includes: determining a characteristic frequency ratio that is a characteristic value among frequency ratios, each of the frequency ratios being a ratio between an actuator driving frequency and an angle of attack changing frequency, the actuator driving frequency being a frequency of an applied voltage applied to the plasma actuator, the angle of attack changing frequency being a frequency at which an angle of attack of the blade changes in accordance with a rotation angle of the blade; setting the actuator driving frequency such that the frequency ratio becomes the characteristic frequency ratio; and applying a voltage of the set actuator driving frequency to the plasma actuator to control the flow around the blade.

Abstract: A high-lift device includes a flap body which is provided at a rear portion of a main wing which generates a lift for the air vehicle such that the flap body is deployed with respect to the main wing and stowed in the main wing and extends along a wingspan direction of the main wing; and a gap increasing section provided at an end portion of the flap body in an extending direction of the flap body, to increase a gap between the rear portion of the main wing and a front portion of the flap body in a state in which the flap body is deployed.

Abstract: A high-lift device includes a flap body which is provided at a rear portion of a main wing which generates a lift for the air vehicle such that the flap body is deployed with respect to the main wing and stowed in the main wing and extends along a wingspan direction of the main wing; and a gap increasing section provided at an end portion of the flap body in an extending direction of the flap body, to increase a gap between the rear portion of the main wing and a front portion of the flap body in a state in which the flap body is deployed.

Abstract: A high-lift device includes a flap body which is provided at a rear portion of a main wing which generates a lift for the air vehicle such that the flap body is deployed with respect to the main wing and stowed in the main wing and extends along a wingspan direction of the main wing; and a gap increasing section provided at an end portion of the flap body in an extending direction of the flap body, to increase a gap between the rear portion of the main wing and a front portion of the flap body in a state in which the flap body is deployed.

Abstract: A high-lift device of a flight vehicle includes: a flap main body provided at a trailing edge portion of a main wing of the flight vehicle so as to be extracted from and be retracted in the trailing edge portion and extending in a wing span direction of the main wing; and a vortex suppressing portion provided at a tip end portion of the flap main body in a wing span direction of the flap main body and configured to suppress a vortex rolling up from a lower surface of a tip end portion of the flap main body to an upper surface of the tip end portion.

Abstract: A high-lift device of a flight vehicle includes: a flap main body provided at a trailing edge portion of a main wing of the flight vehicle so as to be extracted from and be retracted in the trailing edge portion and extending in a wing span direction of the main wing; and a vortex suppressing portion provided at a tip end portion of the flap main body in a wing span direction of the flap main body and configured to suppress a vortex rolling up from a lower surface of a tip end portion of the flap main body to an upper surface of the tip end portion.

Abstract: A high-lift device of a flight vehicle includes: a flap main body provided at a trailing edge portion of a main wing of the flight vehicle so as to be extracted from and be retracted in the trailing edge portion and extending in a wing span direction of the main wing; and a vortex suppressing portion provided at a tip end portion of the flap main body in a wing span direction of the flap main body and configured to suppress a vortex rolling up from a lower surface of a tip end portion of the flap main body to an upper surface of the tip end portion.

Abstract: A high-lift device of a flight vehicle includes: a flap main body provided at a trailing edge portion of a main wing of the flight vehicle so as to be extracted from and be retracted in the trailing edge portion and extending in a wing span direction of the main wing; and a vortex suppressing portion provided at a tip end portion of the flap main body in a wing span direction of the flap main body and configured to suppress a vortex rolling up from a lower surface of a tip end portion of the flap main body to an upper surface of the tip end portion.

Abstract: A method for attenuating aerodynamic noise from a landing gear may include researching a start point of a shear layer as a flow field characteristic of a region in the vicinity of an original shape of the landing gear, and adding a plate-shaped object in the vicinity of the start point, changing the start point to an edge portion of the plate-shaped object to make the shear layer farther from the original shape. Another method for attenuating aerodynamic noise from a landing gear may include researching a static pressure and an airflow velocity in a region in the vicinity of the landing gear as a flow field characteristic of the region, and adding a plate-shaped object covering a surface of the landing gear which is different from a surface facing an upstream side in an airflow direction, increasing the static pressure in the region to reduce the airflow velocity.

Abstract: A high-lift device of a flight vehicle includes: a flap main body provided at a trailing edge portion of a main wing of the flight vehicle so as to be extracted from and be retracted in the trailing edge portion and extending in a wing span direction of the main wing; and a vortex suppressing portion provided at a tip end portion of the flap main body in a wing span direction of the flap main body and configured to suppress a vortex rolling up from a lower surface of a tip end portion of the flap main body to an upper surface of the tip end portion.

Abstract: A high-lift device includes a flap body which is provided at a rear portion of a main wing which generates a lift for the air vehicle such that the flap body is deployed with respect to the main wing and stowed in the main wing and extends along a wingspan direction of the main wing; and a gap increasing section provided at an end portion of the flap body in an extending direction of the flap body, to increase a gap between the rear portion of the main wing and a front portion of the flap body in a state in which the flap body is deployed.

Abstract: A high-lift device of a flight vehicle includes: a flap main body provided at a trailing edge portion of a main wing of the flight vehicle so as to be extracted from and be retracted in the trailing edge portion and extending in a wing span direction of the main wing; and a vortex suppressing portion provided at a tip end portion of the flap main body in a wing span direction of the flap main body and configured to suppress a vortex rolling up from a lower surface of a tip end portion of the flap main body to an upper surface of the tip end portion.

Abstract: A jet noise source modeling method of creating a jet noise source model, includes: setting a plurality of point sound sources by quantizing a strength distribution of a jet noise source determined through an analysis of a jet stream and determining respective sound source strengths of respective point sound sources; and determining respective phases of the respective point sound sources based on a known noise level of a far free sound field related with the jet stream. An aircraft having an airframe capable of insulating the interior thereof from noises is designed on the basis of the results of the analysis.

Abstract: An oil ring mechanism of a piston includes a circumferential ring groove formed in an outer peripheral surface of the piston, and a two-piece oil ring having a ring-shaped ring main body that is arranged in the ring groove and urged in the outer peripheral direction inside the ring groove by a coil expander arranged on the inner peripheral side of the oil ring main body. On lower side surface on a crankcase side of a side wall surface of the ring groove that is on the opposite side of the ring groove from an engine combustion chamber, first and second recessed portions that reduce the abutment area where a lower surface of the ring main body abuts against the lower side surface formed in a lower side abutment surface that serves as a surface for abutting against the lower surface of the ring main body.

Abstract: If an engine undergoes high-load operations immediately after it is started up from its cold state, a thermostat is closed to inhibit passage of cooling water through the inside of the engine, and the cooling water stagnant in a cylinder head receives heat from a combustion chamber. Therefore, the cooling water will possibly boil. However, the thermostat is formed in such a manner that a valve body may be opened forcedly if the discharge flow rate of a water pump is greater than the flow rate in a normal use region. Therefore, in such a situation, the discharge flow rate of the water pump is increased greater than the flow rate in the normal use region to open the valve body with good response, thereby passing water into the engine quickly. This configuration prevents the cooling water stagnant in the cylinder head from boiling before the valve body is opened completely.

Abstract: A piston for an internal combustion engine including: a piston head located at an uppermost section of the piston; a land located on a circumference of the piston head; a skirt located below the land; and a pair of pin bosses located on the lower section of the piston head. The piston head has a first cavity on the bottom of the piston head. Each of the pair of pin bosses has a second cavity in an outer upper section of the pin boss. The pin boss has a through hole that communicably connects the first cavity with the second cavity.

Abstract: A piston (10) for an internal combustion engine including: a piston head (11) located at an uppermost section of the piston; a land (12) located on a circumference of the piston head (11); a skirt (13) located below the land (12); and a pair of pin bosses (14) located on the lower section of the piston head (11). The piston head (11) has a first cavity (24) on the bottom of the piston bead (11). Each of the pair of pin bosses (14) has a second cavity (20) in an outer upper section of the pin boss (14). The pin boss (14) has a through hole (21) that communicably connects the first cavity (24) with the second cavity (20).

Abstract: A small end member constituting a small end, a column member constituting a column portion, and a big end member constituting a big end of a connecting rod are formed as separate members. In addition, the small end member and the big end member are each made of a high-rigidity material, and the column member is made of a high-strength material. These members are integrally bonded by liquid phase diffusion bonding, thus providing a connecting rod that can achieve suppression of stress concentration.