5 results about "Tonal noise" patented technology

In accordance with certain aspects, noise cancellation systems and methods are utilized to mitigate engine tonal noise at sleeping locations in the aircraft cabin space. In one embodiment, an onboard noise cancellation system is provided that includes a plurality of microphones, the plurality of microphones, and a plurality of speakers, and a noise cancellation circuit. In this embodiment the plurality of speakers are arranged proximate to a bed in the sleeping area of the aircraft cabin. Likewise, the plurality of speakers are arranged proximate to the proximate to the bed in the sleeping area. The noise cancellation circuit is further coupled to the plurality of speakers, and the noise cancellation circuit is configured to drive the plurality of speakers to generate noise cancellation audio to at least partially cancel engine noise in a region above the bed.

Gerotor pump (50) comprising the following: a pump housing (52) that defines a chamber (56) and has a fluid inlet (58) and a fluid outlet (60), an outer gear element which is supported for rotation within the chamber (56) about a first axis (98), wherein the outer gear element has a series of internal teeth (96), and an inner gear element rotatably supported within the outer gear element about a second axis (70) spaced apart from the first axis (98), wherein the inner gear element defines a series of external teeth (86) between which a series of external pockets (106) is inserted, wherein the inner gear element forms a continuous fluid passage (160) to fluidically connect two non-adjacent pockets (106) and another pocket (106) independently of the fluid passages (160), wherein the fluid passage (160) is designed to disrupt harmonics during operation in order to reduce pressure ripples and associated tonal noise.

The invention relates to a gear (10) for a gear pair of a vehicle drive train, comprising: a first tooth (11) with a first tooth flank (12) and at least one second tooth (15) with a first tooth flank (17), wherein the first tooth flank (12) of the first tooth (11) has a first modified surface region (13) within a surface (14) of the first tooth flank (12), wherein the first modified surface region (13) and a surface (16) of the first tooth flank (17) of the second tooth (15) differ such that tonal noise generation during operation of the gear pair is reduced. The invention further relates to a gear pair with such a gear, a method for manufacturing such a gear, a drive train, and a vehicle.

An aero-engine circumferential acoustic mode measurement method based on Lp-norm regularization is disclosed. In the method, the highest order m of the circumferential dominant acoustic mode of the fan tonal noise is calculated through the number B of fan rotor blades and the number V of stator blades of the aero-engine. max , based on the highest order m max , determine the number of microphones required under Nyquist sampling arranged circumferentially on the aero-engine fan casing. Randomly select the circumferential installation positions and angles of a predetermined number of installations at the pipeline inlet to install microphones to form a microphone array to collect sound pressure signals. Perform a fast Fourier transform on the sound pressure signals measured by the microphone array, and take the complex amplitude of the sound pressure signal at the blade passing frequency as the observation vector; based on the installation positions and angles and the highest order m max , construct an orthogonal Fourier sensing matrix, establish an Lp-norm non-convex regularized compressive sensing model under non-uniform few measurement points, and use the generalized threshold shrinkage algorithm to obtain the circumferential acoustic mode amplitude of the aero-engine fan tonal noise.

A method of controlling airborne tonal noise which originates from a component of a wind turbine, the wind turbine comprising a vibration control system comprising a plurality of actuators. The method comprising identifying a first operating state of the wind turbine; and selecting a first set of one or more of the actuators on the basis of the identified first operating state. Each actuator of the first set is operated to apply a vibration control oscillation to the component in phase opposition to a vibration of the component, thereby damping the vibration of the component and in turn reducing airborne tonal noise originating from the component. A change of the wind turbine to a second operating state is detected, then a second set of one or more of the actuators is selected on the basis of the identified second operating state. Each actuator of the second set is operated to apply a vibration control oscillation to the component in phase opposition to a vibration of the component, thereby damping the vibration of the component and in turn reducing airborne tonal noise originating from the component.