13 results about "Propeller noise" patented technology

The invention discloses an analysis and prediction method for high-frequency noise of a pod propeller, and the method comprises the following steps: S1, obtaining flow field original data and corresponding high-frequency noise monitoring data of the pod propeller in a working state, and carrying out the preprocessing; and S2, constructing a flow field-noise coupling analysis framework based on the separation vortex model, and setting a time step length and a calculation frequency matched with actual working conditions. The invention relates to the technical field of ship propeller noise analysis and prediction. According to the pod propulsor high-frequency noise analysis and prediction method, flow field vortex structure characteristics can be captured by constructing a flow field-noise coupling analysis framework and processing the preprocessed flow field data, and the contribution degree of each vortex unit to the high-frequency noise is accurately calculated based on a vortex structure and noise generation correlation mechanism, so that the high-frequency noise analysis and prediction method is provided for the high-frequency noise analysis and prediction of the pod propulsor. The vortex units leading the noise source are screened, dynamic positioning of the high-frequency noise source is achieved by combining the space-time position information of the vortex units, and the source of noise generation can be deeply known.

The invention provides a large and medium-sized water surface ship radiation noise generation and control method, system and device covering a scale effect, and a storage medium, and belongs to the field of large and medium-sized water surface ship radiation noise prediction and analysis. The difference of contribution degrees of machinery, hydrodynamic force and propeller noise to underwater radiation noise in different navigation states is considered, a multi-modal noise separation method is adopted to separate coupling components, and a ship underwater radiation noise source is simplified into a noise source model along a ship body; a ship scale effect analysis and multi-resolution time-frequency analysis technology is introduced, and a generation mechanism of ship radiation noise is simplified into underwater radiation noise caused by shell vibration caused by the fact that a plurality of distributed low-frequency loads act on a ship structure; large and medium water surface ship radiation noise passing characteristic rules are disclosed, and a ship navigation state underwater radiation noise simulation theoretical model is established. According to the method, an effective means is provided for generation and control of underwater noise of the ship, and optimization of ship design and reduction of underwater radiation noise are facilitated.

This invention relates to the field of passive underwater target identification technology, and in particular to a propeller noise cyclic coherent demodulation method based on an improved real-number genetic algorithm. Based on cyclic stationarity analysis theory, an optimal coherent weighted quadratic envelope spectrum is constructed by replacing the fixed integration frequency band with a weighting function, and an adaptive detection threshold is constructed based on the false alarm probability. The observed spectrum is modeled as the sum of harmonics and noise, and a sparse non-negative optimization problem is solved to extract the harmonics. Using the total harmonic intensity of the envelope spectrum as the cost function, an improved real-number genetic algorithm is used to optimize and search for the optimal weighting coefficient vector. The demodulated spectrum is obtained by coherently weighting and integrating the normalized cyclic modulation spectrum. This invention achieves autonomous allocation of weighting coefficients and adaptive selection of demodulation frequency bands, effectively improving the signal-to-noise ratio gain of cyclic demodulation, and is applicable to passive target identification in data backtracking and review systems.

This invention relates to a method and system for locating coaxial counter-rotating sound sources in rotorcraft, belonging to the technical field of sound source identification methods. It includes: processing the sound pressure signal of the moving sound source using continuous wavelet transform to obtain time-frequency domain variation results; performing Doppler effect correction based on experimental conditions; estimating the spatial location and relative intensity of the noise source using a cross-spectral matrix and weight vector; and performing phase-locked analysis of the rotor noise source intensity using a phase-locked averaging method. This invention differs from traditional time-domain delay superposition algorithms and frequency-domain cross-correlation spectrum methods. It can image unsteady sound sources using time-frequency domain characteristics, solving the acoustic imaging problem of counter-rotating propeller noise and possessing potential applications in the rotorcraft industry.

This invention relates to the field of ship design and propulsion technology, and discloses a catamaran and its control method. The catamaran includes a hull, with the width direction defined as the direction perpendicular to the catamaran's direction of travel in a horizontal plane. The hull includes a first hull and a second hull arranged symmetrically and at intervals along the width direction, with a channel formed between the first and second hulls along the width direction. It also includes a propulsion assembly disposed in the channel, comprising at least one fin adapted to oscillate to drive the catamaran's movement. This invention solves the problems of high propeller noise, cavitation, and difficulty in towing loads in related technologies for catamarans.

The application discloses a kind of analysis and prediction methods of high-frequency noise of pod propeller, comprising the following steps: S1, obtain the flow field original data and corresponding high-frequency noise monitoring data under the working state of pod propeller, and pre-process;S2, based on the separated vortex model, construct flow field-noise coupling analysis framework, set the time step and calculation frequency matched with actual working condition, the present application relates to ship propeller noise analysis and prediction technical field.The analysis and prediction method of high-frequency noise of the pod propeller, by constructing flow field-noise coupling analysis framework, the pre-processed flow field data are processed, the vortex structure characteristics of flow field can be captured, and based on the correlation mechanism of vortex structure and noise generation, the contribution of each vortex unit to high-frequency noise is accurately calculated, the vortex unit of dominant noise source is screened, and the dynamic positioning of high-frequency noise source is realized in combination with its space-time position information, which helps to understand the root of noise generation.

The application provides a paddle, a propeller, a power propulsion device and a ship, and relates to the technical field of propeller noise control, wherein the paddle comprises a blade root, a blade body and a blade tip which are sequentially connected; the blade body has a first pressure surface and a first suction surface which are oppositely arranged, in the process of rotation of the paddle, fluid can flow from the position of the first pressure surface to the position of the first suction surface; at least a part of the blade tip is curved towards the first pressure surface. In the technical scheme of the application, at least a part of the blade tip is curved towards the first pressure surface of the blade body, and this design is beneficial to the structural optimization of the blade tip, can greatly inhibit vortex-induced resonance and reduce noise pollution.

The invention discloses an amphibious vehicle propeller noise control system and method based on PID adjustment, and belongs to the technical field of automobile control, and the amphibious vehicle propeller noise control system based on PID adjustment combines a PID adjustment algorithm with an active noise reduction algorithm, monitors an external environment, adjusts dynamic variable parameters, and improves the noise reduction performance of the amphibious vehicle propeller. The control parameters are converted into propeller control parameters and active noise reduction module control parameters to control noise reduction parameters of an impeller adjusting mechanism and a microphone, and finally noise reduction signals processed through an algorithm are used for sending out reverse sound waves through a loudspeaker to reduce noise in a vehicle.

This invention discloses a method for simulating radiated noise signals from a counter-rotating propeller target, comprising: First, setting basic parameters of the counter-rotating propeller target, including simulation time, simulation harmonics, and signal-to-noise ratio (SNR). Second, setting signal parameters of the counter-rotating propeller target under stable navigation conditions, including noise fundamental frequency and frequency fluctuation variance, and setting signal parameters of the counter-rotating propeller target under maneuvering conditions, including maneuvering time and fundamental frequency increment. Third, generating signal frequency curves based on the signal parameters of the counter-rotating propeller target under stable navigation and maneuvering conditions. Fourth, calculating the signal phase point by point based on the counter-rotating propeller target signal frequency curves to generate a simulated counter-rotating propeller noise line spectrum signal. Fifth, adding noise according to the SNR and summing the results to generate a simulated counter-rotating propeller target noise signal. This method can accurately describe the time-varying frequency characteristics under different conditions, ensuring phase continuity and time-frequency consistency.

This invention provides a method and system for mathematical noise cancellation of propellers based on FFT. It involves processing the time-domain signal data of propeller noise using FFT to obtain a frequency-domain signal. This frequency-domain signal is then plotted as a spectrum with frequency on the horizontal axis and sound pressure level on the vertical axis. The spectrum is used to determine whether a singing tone exists within the frequency-domain signal of the propeller noise. If a singing tone is present, it is categorized into three types based on its influence range and position within the full frequency band of the spectrum: Type I, Type II, and Type III. Different judgment and calculation methods are then used to eliminate the singing tone in each of these three types, thus completing the noise cancellation of the propeller. This invention does not require time or financial costs to modify the propeller model, nor does it require changing the rated operating conditions in the original experimental plan.

This invention belongs to the field of vertical takeoff and landing (VTOL) aircraft technology, specifically relating to a noise-controllable VTOL aircraft propeller design method and implementation device. The design method includes steps such as selecting key positions in the blade spanwise direction and determining the basic airfoil, optimizing the airfoil at the key positions, constructing a preliminary propeller configuration, investigating the influence of chord length, negative torque, and blade number on noise, determining the basic propeller configuration and optimization range, and optimizing the propeller aerodynamic performance. This method starts with optimizing the airfoil at the key positions of the blade, gradually investigating the influence of chord length, negative torque, and blade number on propeller noise, determining the basic propeller configuration and optimization range with acceptable noise, and performing multi-objective aerodynamic optimization based on this. This improves the aerodynamic efficiency of the propeller, reduces the noise level, and reduces trial and error costs and time. It can provide a high-performance, low-noise propeller design scheme for VTOL aircraft, meeting their application needs in complex environments such as urban air traffic.

The invention discloses an intelligent hydrofoil noise reduction device and method based on reinforcement learning, and belongs to the technical field of propeller noise reduction. The intelligent hydrofoil noise reduction device comprises a propeller, the propeller is connected with a control box and installed in a transparent water tank, and the control box is used for adjusting the rotating speed and the incoming flow speed; the intelligent hydrofoils are connected with the propellers, telescopic devices are mounted in the hydrofoils, the telescopic devices change the hydrofoil mounting spacing ratio and the hydrofoil length, and propeller hub rings for changing the circumferential mounting positions are mounted at the roots of the intelligent hydrofoils; the arrays of the pressure sensors are installed on the surface of the propeller hub ring and the surface of the intelligent hydrofoil respectively and used for collecting unsteady pressure pulsation data, and the pressure sensors are connected with the data center. And the active control system adjusts the optimal vortex reduction angle of the hydrofoil under the current working condition so as to realize efficient self-adaptive noise reduction. The method can effectively weaken the propeller hub vortex, improve the flow field structure, obviously reduce the propeller noise, reduce the dependence on physical experiments, improve the optimization efficiency and reduce the cost.

The application discloses a UAV noise cancellation method and device for cross-medium direct acoustic communication, and the method comprises the following steps: sampling a known probe signal and a received signal, obtaining a frequency domain expression, and calculating a cross-medium sound pressure transmission function to extract an amplitude response, a phase response and a group delay; based on a normalized ratio and a local maximum value detection method, a center frequency set of a UAV propeller noise is identified; a notch depth, a bandwidth, a frequency compensation and a phase compensation are determined in combination with channel characteristic parameters to construct a cascaded notch filter; channel characteristic parameters are input into a deep learning model to output a filter parameter correction amount, dynamic updating of the filter is realized, a filter capable of suppressing noise is obtained, and a communication signal after noise reduction is obtained. The application can realize accurate detection of propeller noise frequency and multi-dimensional adaptive adjustment of filter parameters.