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31 results about "Advance ratio" patented technology

In aeronautics and marine hydrodynamics, the advance ratio is the ratio of the freestream fluid speed to the propeller, rotor, or cyclorotor tip speed. When a propeller-driven vehicle is moving at high speed relative to the fluid, or the propeller is rotating slowly, the advance ratio of its propeller(s) is a high number; and when it is moving at low speed, or the propeller is rotating at high speed, the advance ratio is a low number. The advance ratio is a useful non-dimensional velocity in helicopter and propeller theory, since propellers and rotors will experience the same angle of attack on every blade airfoil section at the same advance ratio regardless of actual forward speed. It is the inverse of the tip speed ratio used for wind turbines.

Rotor collective pitch VS Mu to control flapping and mast/rotor tilt to control rotor RPM

ActiveUS7448571B1Minimum rotation speedPropellersRotocraftLow speedFlight vehicle
A method of operating a rotor aircraft involves measuring an airspeed of the aircraft and a rotational speed of the rotor. A controller determines a Mu of the rotor based on the airspeed of the aircraft and the rotational speed of the rotor. The controller varies the collective pitch of the rotor blades in relationship to the Mu, from an inertia powered jump takeoff, through high speed high advance ratio flight, through a low speed landing approach, to a zero or short roll flare landing. In addition as the rotor is unloaded and the rotor slows down, the controller maintains a minimum rotor RPM with the use of a tilting mast.
Owner:JAUNT AIR MOBILITY LLC

Two-place, collective pitch and throttle control

A heliplane operates with a fixed wing at high velocities, and particularly at high advance ratios, while using a rotary wing maintained in motion at all speeds. At high advance ratios, the rotor wing eventually may be rotated primarily to maintain its stability, rather than depending upon the majority of lift. Meanwhile, a collective pitch control is provided and located between pilot and copilot. A single control provides control of both collective pitch and throttle by both pilots. One pilot will have to operate the control with the left hand, while the other may use their right hand. Nevertheless, both throttles push away from the pilot, regardless of which one is in control of the aircraft, while a single collective lever is relied upon.
Owner:SKYWORKS GLOBAL INC

Wind tunnel test method for coaxial double-rotor hub model of helicopter

The invention discloses a wind tunnel test method for a coaxial double-rotor hub model of a helicopter, and belongs to the field of hub wind tunnel test methods. According to the method, a large-advance-ratio coaxial double-rotor hub model flow mechanism and a pneumatic interference test can be carried out. The method comprises the following steps of firstly, installing a test bed in a wind tunnel, and carrying out coaxial synchronous reverse rotation motion of the model through the test bed; secondly, monitoring a vibration level of the test bed in real time by a vibration monitoring system,and researching dynamic characteristics of the test bed; thirdly, measuring six force factors of the model by a box type balance, measuring a flow field of the model by a PIV flow field measuring system, and measuring the surface pressure of the model by an electronic scanning pressure measuring system or a pressure sensor; fourthly, during a test process, replacing components of the coaxial double-rotor hub model according to the need in order to research the aerodynamic characteristics of the model with different appearances or different flow control modes; and finally, obtaining the aerodynamic characteristics of the model. According to the method, a problem of measurement of the aerodynamic characteristics of the rotating coaxial double-rotor hub model is solved.
Owner:LOW SPEED AERODYNAMIC INST OF CHINESE AERODYNAMIC RES & DEV CENT

Rotor aircraft tilting hub with reduced drag rotor head and mast

ActiveUS7510377B1Eliminating oscillatory featheringSimple tilting spindlePropulsive elementsReaction enginesDrive shaftEngineering
A rotor aircraft has a tilting hub for cyclic control operated by either a tilting spindle or swash plate mounted to the upper end of the drive shaft. A spinner housing with two separate half portions encloses the hub. The blades of the rotor have root portions that are integrally joined to the separate half portions. During a collective pitch change, the half portions rotate relative to each other, but at advance ratios greater than about 0.7, when the collective can be held constant, the spinner half portions can be in perfect alignment. Concentric control sleeves surround the drive shaft for changing collective pitch as well as cyclic pitch.
Owner:JAUNT AIR MOBILITY LLC

Blower

A blower includes: an impeller on which there are arranged axial flow blades 40 mounted at circumferential intervals to an outer peripheral surface of a boss; a case surrounding the impeller; and a bell mouth cylindrically constricted to guide gas into the case, wherein an inner diameter of the bell mouth is smaller than an outer diameter of the impeller. Further, each blade has, in the radial direction, a sweepforward wing portion situated on the boss side and exhibiting a positive advance ratio value, and a sweepback wing potion situated on the outer peripheral side of the blade and exhibiting a negative advance ratio value, with the arc length of each blade increasing from the boss side toward the outer peripheral side. Therefore, it is possible to achieve an improvement in ventilation efficiently, through an increase in static pressure and to achieve a reduction in noise.
Owner:MITSUBISHI ELECTRIC CORP

Anhedral Tip Blades for Tiltrotor Aircraft

A tiltrotor aircraft having a fixed wing and tilting rotors has a rotor blade with a shaped tip portion that provides improved hover performance. The shaped tip portion preferably has a terminal anhedral of at least 20° with respect to its stacking line, and the blade has an overall twist from root to tip of at least 20°, and a thickness ratio between 19% and 30% at a radial station of 10%. These features advantageously conspire to provide a hover figure of merit of at least 0.84 and a cruise propulsive efficiency of at least 0.85. A controller preferably limits the rotor speed in sustained airplane-mode forward flight cruise of at most 40% of a hover maximum rotor speed, and alternatively or additionally limits a rotor edgewise advance ratio to at most 0.20.
Owner:KAREM AIRCRAFT INC

Propulsion device of underwater robot and underwater robot

InactiveCN108082436ARealization of multi-degree-of-freedom motionFull monitoring perspectiveSteering ruddersPropulsive elementsControl systemAdvance ratio
The invention discloses a propulsion device of an underwater robot. The propulsion device comprises a balance part, propellers and a driving mechanism for regulating an advance direction of the propellers; the balance part is used for keeping the propulsion device balanced; and an underwater robot includes the propulsion device and a control system for controlling the propulsion device to enable directional movement of the underwater robot, and the control system is electrically connected with the propulsion device. According to the propulsion device of the underwater robot, the propellers andthe driving mechanism are arranged, and the main function of the driving mechanism is to adjust the advance direction of the propellers; and by changing the advance direction of the propellers, morefreedom of movement of the propulsion device can be achieved, thereby achieving more freedom of movement of the underwater robot. According to the underwater robot, the propulsion device and the control system are arranged, and more freedom of movement of the underwater robot can be realized through the cooperative action of the control system and the propulsion device, thereby achieving a more complete perspective of the underwater robot monitoring.
Owner:SOUTHWEST PETROLEUM UNIV

Apparatus and method for roll moment equalization at high advance ratios for rotary wing aircraft

A method for equalizing rolling moments at high advance ratios is disclosed including impelling an aircraft in a forward direction at an airspeed by means of a thrust source and rotating a rotor of the aircraft at an angular velocity with respect to the airspeed effective to cause a positive total lift on each blade due to air flow over the blades in the retreating direction when the blade is moving in the retreating direction. The rotor includes an even number of blades placed at equal angular intervals around the rotor hub. One or both of cyclic pitch and rotor angle of attack are adjusted such that a rolling moment of the retreating blade due to reverse air flow is between 0.3 and 0.7 times a rolling moment on the advancing blade due to lift.
Owner:SKYWORKS GLOBAL INC

Data correction method of high-altitude propeller wind tunnel test for influence of Reynolds number

The invention provides a data correction method of a high-altitude propeller wind tunnel test for influence of Reynolds number. The data correction method comprises the following steps: according to the similarity criterion of an advance ratio and a tip Mach number, experimental parameters of the high-altitude propeller scale model wind tunnel test are determined; the wind tunnel test of the propeller scale model is carried out; a tension coefficient experimental value C<T,exp> and a power coefficient experimental value C<P,exp> are measured; the tension coefficient experimental value and thepower coefficient experimental value are corrected; and a corrected propeller propulsion efficiency is calculated according to a propeller propulsion efficiency formula. The invention takes into account the difference between the Reynolds number experimental value under the condition of the equal advance ratio and the equal tip Mach number and the Reynolds number under the real working condition of the high-altitude propeller; more accurate aerodynamic performance experimental data such as the high-altitude propeller tension coefficient, the power coefficient and the propulsion efficiency is obtained by using the proposed correction method; so reliable basic data is provided for designing a propulsion system and an energy system of a high-altitude low-dynamic aircraft.
Owner:NORTHWESTERN POLYTECHNICAL UNIV

Steady state differential roll moment control with automated differential lateral control

A method for controlling a differential rotor roll moment for a coaxial helicopter with rigid rotors, the method including receiving, with a processor, a signal indicative of a displacement command from a controller; receiving, with the processor via a sensor, one or more signals indicative of a longitudinal velocity, an angular velocity of one or more rotors and an air density ratio for the helicopter; determining, with the processor, a ganged collective mixing command in response to the receiving of the displacement command; determining, with the processor, a rotor advance ratio as a function of the longitudinal velocity and the angular velocity; and determining, with the processor, a corrective differential lateral cyclic command for the rigid rotors that controls the differential rotor roll moment to a desired value.
Owner:SIKORSKY AIRCRAFT CORP

Propeller engine matching optimization method suitable for long-endurance turboprop power unmanned aerial vehicle

The invention relates to aircraft design, in particular to a propeller engine matching optimization method suitable for a long-endurance turboprop power unmanned aerial vehicle. The method comprises the following steps: 1, calculating a matching power coefficient according to aerodynamic characteristic data of a propeller; 2, calculating matching power coefficients under different power coefficients CP and advancing ratios J to obtain a corresponding relation between the propeller efficiency and the matching power coefficients; 3, designing a flight working condition, and giving a matching power coefficient under the position of an engine air door; and 4, determining the optimal efficiency and the advancing ratio corresponding to the matching power coefficient according to the corresponding relation in the step 2 and the step 3 and the matching power coefficient. Through selection of matching working points of the engine and the propeller, the shaft power of the engine is fully utilized, the propulsion efficiency is improved, and the optimal flight performance of the aircraft in the whole flight envelope can be achieved.
Owner:CHENGDU AIRCRAFT DESIGN INST OF AVIATION IND CORP OF CHINA

Ducted propeller equivalent advance ratio working condition calculation method

The invention discloses a ducted propeller equivalent advance ratio working condition calculation method. According to the method, fitting is conducted on the relation of the tension coefficient under a certain angle of attack of an open propeller and the advance ratio through an equation; the ducted tension factor q and the outlet area ratio sigma are determined; a thin cylindrical ducted propeller calculation formula is adopted for the ducted tension factor q; the open propeller tension T1 is obtained by inputting the rotating speed and the current advance ratio, the initial V1 is worked out through the formula (please see the formula in specification), and the equivalent incoming flow speed V0 is calculated through the formula (please see the formula in specification); the equivalent advance ratio lambada n is obtained through the equivalent incoming flow V0 and the current rotating speed; judgment and convergence are conducted. The method is simple, easy to implement and free of tests or massive fluid mechanics calculation and has larger operation efficiency and convenience.
Owner:COOL HIGH TECH BEIJING CO LTD

Large-advance-ratio rotor blade reverse flow velocity active control trailing edge winglet device

ActiveCN113602489AReverse flow controlRelieves regurgitation aerodynamicsRotocraftReciprocating motionGear wheel
The invention discloses a large-advance-ratio rotor blade reverse flow velocity active control trailing edge winglet device which comprises a main rotor and a reverse arc winglet arranged at the trailing edge of the main rotor, a transmission device is arranged in the main rotor, and the transmission device is used for driving the reverse arc winglet to do sinusoidal oscillation motion; the transmission device comprises a motor, an eccentric wheel, a reciprocating sliding block and a transmission gear set, the motor drives the eccentric wheel to rotate so as to drive the reciprocating sliding block to do linear reciprocating motion, a rack is arranged at the end, away from the eccentric wheel, of the reciprocating sliding block and meshed with the transmission gear set, a small wing gear meshed with the transmission gear set is arranged in the reverse arc small wing, and the rack drives the transmission gear set to rotate so as to drive the small wing gear to rotate. The reverse arc winglet does sinusoidal oscillation motion on the rear edge of the main rotor, the rear edge is reversely folded through curved surface deformation, the wing type rear edge can be more tightly aligned with oncoming airflow, and therefore the reverse flow aerodynamic problem is greatly solved, and the reverse flow velocity is controlled.
Owner:LOW SPEED AERODYNAMIC INST OF CHINESE AERODYNAMIC RES & DEV CENT

Correction method of high-altitude propeller wind tunnel test data for the influence of Reynolds number

The invention provides a data correction method of a high-altitude propeller wind tunnel test for influence of Reynolds number. The data correction method comprises the following steps: according to the similarity criterion of an advance ratio and a tip Mach number, experimental parameters of the high-altitude propeller scale model wind tunnel test are determined; the wind tunnel test of the propeller scale model is carried out; a tension coefficient experimental value C<T,exp> and a power coefficient experimental value C<P,exp> are measured; the tension coefficient experimental value and thepower coefficient experimental value are corrected; and a corrected propeller propulsion efficiency is calculated according to a propeller propulsion efficiency formula. The invention takes into account the difference between the Reynolds number experimental value under the condition of the equal advance ratio and the equal tip Mach number and the Reynolds number under the real working condition of the high-altitude propeller; more accurate aerodynamic performance experimental data such as the high-altitude propeller tension coefficient, the power coefficient and the propulsion efficiency is obtained by using the proposed correction method; so reliable basic data is provided for designing a propulsion system and an energy system of a high-altitude low-dynamic aircraft.
Owner:NORTHWESTERN POLYTECHNICAL UNIV

Correction method of high-altitude propeller wind tunnel test data for the influence of tip Mach number

The invention provides a high-altitude propeller wind tunnel test data correction method aiming at the influence of a tip Mach number, which comprises the following steps of: determining test parameters of a wind tunnel test of a high-altitude propeller scaling model according to an advance ratio and a Reynolds number similarity criterion; performing the wind tunnel test on the propeller scaling model to obtain a tension coefficient test value C<T, exp> and a power coefficient test value C<p, exp>; and correcting the tension coefficient test value and the power coefficient test value, and calculating according to a propeller propulsion efficiency formula to obtain a corrected propeller propulsion efficiency. According to the high-altitude propeller wind tunnel test data correction method,the difference between a tip Mach number test value under the conditions of equal advance ratio and equal Reynolds number and a tip Mach number under the real working condition of a high-altitude propeller is considered, and the provided high-altitude propeller wind tunnel test data correction method is utilized to obtain accurate aerodynamic performance test data such as a tension coefficient, apower coefficient, a propulsion efficiency and the like of the high-altitude propeller, so that reliable basic data are provided for the design of a propulsion system and an energy system of a high-altitude low-dynamic aircraft.
Owner:NORTHWESTERN POLYTECHNICAL UNIV

Cruise propeller matching optimization method suitable for piston power unmanned aerial vehicle

The invention discloses a cruise propeller matching optimization method suitable for a piston power unmanned aerial vehicle. The method comprises the following steps of: introducing a required thrust matching coefficient CR by taking thrust required for aircraft cruise as an entry point and utilizing a thrust coefficient and a forward ratio so as to eliminate coupling characteristics of a propeller speed and an engine speed, and establishing a corresponding relation between the engine speed and propeller efficiency; the minimum unit thrust fuel consumption (SFC) serves as a design target, matching working points of an engine and a propeller are selected, the optimal engine rotating speeds corresponding to different air doors of the engine are set, the minimum cruising fuel consumption is achieved on the premise that the cruising thrust requirement is met, and an aircraft can obtain the optimal endurance performance. The selection process of the matching working points of the engine and the propeller is greatly simplified, and the matching working efficiency of the propeller engine of the piston propeller power unmanned aerial vehicle is remarkably improved; and a design basis can be provided for a wind tunnel test of a complete machine with a propeller, engine control logic rotating speed setting and the like, and finally, the flight endurance performance of the aircraft is optimized and improved.
Owner:CHENGDU AIRCRAFT DESIGN INST OF AVIATION IND CORP OF CHINA

Steady state differential roll moment control with automated differential lateral control

A method for controlling a differential rotor roll moment for a coaxial helicopter with rigid rotors, the method including receiving, with a processor, a signal indicative of a displacement command from a controller; receiving, with the processor via a sensor, one or more signals indicative of a longitudinal velocity, an angular velocity of one or more rotors and an air density ratio for the helicopter; determining, with the processor, a ganged collective mixing command in response to the receiving of the displacement command; determining, with the processor, a rotor advance ratio as a function of the longitudinal velocity and the angular velocity; and determining, with the processor, a corrective differential lateral cyclic command for the rigid rotors that controls the differential rotor roll moment to a desired value.
Owner:SIKORSKY AIRCRAFT CORP

Calculation method for improving balancing convergence of rotor with large forward ratio

The invention belongs to the helicopter rotor design and theoretical modeling technology, discloses a calculation method for improving the balancing convergence of a rotor with a large forward ratio,wherein the method adopts a successive approximation method and a residual monitoring method to improve a rotor balancing calculation method, and is different from a traditional balancing iterative calculation method. According to the calculation method for improving the balancing convergence of the rotor with the large forward ratio, encryption division is carried out on forward ratio parameters,a successive approximation method is used for calculating and monitoring residual error changes in an iterative loop in real time, the calculation capacity of rotor trim is effectively expanded, thetrim solving precision is guaranteed, and the divergence problem in trimming iteration is effectively avoided in a large-advance-ratio state.
Owner:CHINA HELICOPTER RES & DEV INST

Coaxial homodromous propeller with variable phase difference

The invention discloses a coaxial homodromous propeller with variable phase difference. Two propellers with coincident rotating shafts are arranged front and back in the thrust direction of the propellers and comprise front propellers, propeller rotating shafts, sliding sleeves and rear propellers. The two propellers rotate in the same direction. A certain phase difference exists between the rear propeller and the front propeller to ensure that the rear propeller is far away from the wake flow spiral surface of the front propeller. In the actual operation process, if the wake flow helicoid approaches the rear propeller due to the change of the forward ratio, the rear propeller adjusts the phase difference formed between the rear propeller and the front propeller through the forward and backward movement of the sleeve, so that the rear propeller can still be located outside the wake flow area of the front propeller. According to the invention, adverse aerodynamic interference and aerodynamic noise of a coaxial propeller system are reduced.
Owner:BEIHANG UNIV
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