186 results about "Drag coefficient" patented technology

The invention provides an aircraft aerodynamic configuration design method and device based on simulation, and relates to the technical field of aircraft aerodynamic configuration design, and the method comprises the steps: obtaining aerodynamic characteristic parameters of aircrafts of different airfoils to construct a multi-source aerodynamic database; a neural network model is established based on the database, airfoil geometric parameters serve as input, the lift coefficient, the resistance coefficient and the lift-drag ratio serve as labels for training, and an aerodynamic performance prediction model is obtained; candidate combinations are generated in an airfoil geometric parameter design space, aerodynamic characteristics of the candidate combinations are predicted through a model, a fitness function is optimized by utilizing dynamic weights, and the combination with the highest fitness is selected as an optimized airfoil parameter by adopting a genetic algorithm; and performing simulation verification on the optimization parameters, extracting a simulation result, comparing the simulation result with the output of the prediction model, judging that the optimization combination is effective when an error meets a preset requirement, and completing aerodynamic configuration design accordingly. The method improves the prediction accuracy and design efficiency of aerodynamic performance.

The invention relates to the technical field of ship design optimization, and discloses a hull shape optimization method based on neural network modeling. In the data acquisition stage of the method, initial appearance parameters and hydrodynamic performance data of a ship body are obtained, the appearance parameters comprise geometric dimensions and shape features, and the performance data comprise resistance coefficients and wave-making resistance values. In the neural network construction stage, a neural network model with a multi-layer perceptron structure is trained by using collected data, weights are updated through a back propagation algorithm, and a nonlinear mapping relation between appearance parameters and hydrodynamic performance indexes is established. In the shape optimization stage, the trained neural network model is used for carrying out iterative adjustment on the shape of the ship body, fluid dynamic performance indexes are recalculated through the model after each adjustment until preset convergence conditions are met, and finally optimized ship body shape data are output. According to the method, partial complex calculation is replaced by the neural network, and intelligent optimization of the hull appearance is realized.

The invention provides a joint prediction method and system for a wind resistance coefficient and a surface pressure field of an automobile, and relates to the technical field of automobile aerodynamics. According to the joint prediction method, the pressure field and the wind resistance coefficient are predicted in the same network in parallel, and the wind resistance coefficient obtained by pressure field integration and derived from the pressure field and the wind resistance coefficient obtained by network direct regression are calibrated by physical consistency constraint. The model has physical confidence and interpretability while ensuring numerical precision, so that a key stress area can be positioned and serves an automobile modeling iteration process.

A golf ball is disclosed herein that has at least one modified aerodynamic characteristic or performance trait. More specifically, the golf ball disclosed herein can include a dimple pattern having a specific drag coefficient and / or specific integrated drag area.

A golf ball is disclosed herein that has at least one modified aerodynamic characteristic or performance trait. More specifically, the golf ball disclosed herein can include a dimple pattern having a specific drag coefficient and / or specific integrated drag area.

A golf ball is disclosed herein that has at least one modified aerodynamic characteristic or performance trait. More specifically, the golf ball disclosed herein can include a dimple pattern having a specific drag coefficient and / or specific integrated drag area.

A golf ball is disclosed herein that has at least one modified aerodynamic characteristic or performance trait. More specifically, the golf ball disclosed herein can include a dimple pattern having a specific drag coefficient and / or specific integrated drag area.

A golf ball is disclosed herein that has at least one modified aerodynamic characteristic or performance trait. More specifically, the golf ball disclosed herein can include a dimple pattern having a specific drag coefficient and / or specific integrated drag area.

The invention discloses a design method for a propeller of a hydrogen energy power logistics unmanned aerial vehicle. The design method comprises the steps that overall design parameters of the unmanned aerial vehicle and basic parameters of blades of the propeller are determined; selecting a basic airfoil based on the overall design parameters, and constructing a proxy model for airfoil optimization by taking a target lift coefficient as a design point, keeping the maximum thickness of the airfoil unchanged to a constraint and taking a minimum resistance coefficient as targets; based on the blade design objective function and the design variable, blade appearance design optimization is carried out, and chord length distribution parameters and torsion angle distribution parameters of airfoils of all station positions of the blade are determined according to the minimum energy loss principle; performing three-dimensional modeling on the propeller based on the chord length distribution parameters and the torsion angle distribution parameters of the airfoils of all the station positions of the blades to obtain a propeller three-dimensional model; performing performance calculation on the propeller three-dimensional model to obtain propeller tension and power at different rotating speeds and wind speeds; and comparing the pulling force and power of the propeller at different rotating speeds and wind speeds with design parameters, and determining the initial shape of the propeller.

A golf ball is disclosed herein that has at least one modified aerodynamic characteristic or performance trait. More specifically, the golf ball disclosed herein can include a dimple pattern having a specific drag coefficient and / or specific integrated drag area.

A golf ball is disclosed herein that has at least one modified aerodynamic characteristic or performance trait. More specifically, the golf ball disclosed herein can include a dimple pattern having a specific drag coefficient and / or specific integrated drag area.

A golf ball is disclosed herein that has at least one modified aerodynamic characteristic or performance trait. More specifically, the golf ball disclosed herein can include a dimple pattern having a specific drag coefficient and / or specific integrated drag area.

The invention discloses an aerodynamic airfoil profile generation method based on a de-noising diffusion probability model and a variational auto-encoder in the technical field of deep learning and aerodynamic design, which comprises the following steps of: 1, acquiring airfoil profile set data from a public database, re-dividing airfoil profile coordinate points, and calculating a lift coefficient and a resistance coefficient of the airfoil profile set data; 2, preprocessing the airfoil profile data; 3, constructing a joint model based on a variational auto-encoder and a de-noising diffusion probability model, and generating airfoil profile potential representation meeting design conditions by learning potential space representation and combining the de-noising diffusion probability model; 4, inputting the re-divided airfoil profile coordinate point data set into the potential spatial diffusion model for training; and step 5, based on the trained potential spatial diffusion model, inputting different design conditions, and generating an airfoil profile sample conforming to specified geometric characteristics, and according to the method, a high-quality airfoil profile can be generated under different aerodynamic constraint conditions, so that the feasibility and reliability of aerodynamic configuration optimization are improved.

A golf ball is disclosed herein that has at least one modified aerodynamic characteristic or performance trait. More specifically, the golf ball disclosed herein can include a dimple pattern having a specific drag coefficient and / or specific integrated drag area.

The invention belongs to the technical field of launching platforms, and particularly relates to a same-projectile different-shot average trajectory difference evaluation method which comprises the following steps: step 1, establishing a trajectory simulation model; 2, carrying out an average ballistic performance difference check test; 3, identifying a zero resistance coefficient; 4, coincidence calculation is carried out; step 5, determining equivalent distributed source parameter distribution characteristics; 6, equivalent current-day error source parameter distribution characteristics are determined; 7, estimating a system error; 8, evaluating the average ballistic difference of the non-test supporting points; step 9, reconstructing a trajectory; and step 10, evaluating the average ballistic difference of the test supporting points. Compared with the prior art, the method has the advantages that test supporting point average ballistic difference evaluation with low consumption, low false risk and high credibility can be realized; and non-test supporting point average ballistic performance difference evaluation information can be given, and comprehensive evaluation is realized.

The invention discloses a method and a system for rapidly evaluating aerodynamic performance of an automobile body appearance. The method specifically comprises the following steps: generating a geometric curved surface sample of an automobile body surface by adopting a parameterized design method; carrying out fluid numerical analysis on a vehicle body external flow field; an encoder for vehicle body appearance surface geometry is established, and the geometric structure of the vehicle body surface is recognized; establishing a prediction model based on a multi-scale map neural network, and performing geometric data memory, transmission and updating on the flow field of the vehicle body appearance surface; and outputting vehicle body aerodynamic characteristic parameters (a resistance coefficient, a lift coefficient and a lateral force coefficient) and an error level. Compared with the prior art, the neural network algorithm is ingeniously designed, rapid prediction of the aerodynamic characteristic parameters of the automobile body is achieved, the method can be used for rapid performance evaluation in the automobile body development process, the design efficiency is improved, and the development cost is reduced.

The invention discloses an excavator heat balance performance prediction method, system and device and a storage medium. The method comprises the steps that a heat balance performance test of a standard excavation working condition is conducted; respectively establishing an engine heat dissipating capacity Qw calculation model and an engine air inflow mair calculation model; obtaining Qw and mair under the standard excavation working condition; building a one-dimensional cooling system model; cabin resistance coefficient calibration is completed; setting the heat dissipation power of the hydraulic system, calculating the real-time oil temperature of the hydraulic oil tank based on the one-dimensional cooling system model, adjusting the heat dissipation power of the hydraulic system to enable the difference value between the real-time oil temperature of the hydraulic oil tank and the oil temperature of the hydraulic oil tank to be smaller than a set value, and calculating the ratio b of the heat dissipation power of the hydraulic system to the engine power; and on the basis of a calculation model of Qw and mair, b and the calibrated cabin resistance coefficient, predicting the heat balance performance of the excavator under the target working condition. According to the method, the design accuracy and economy can be improved, the prediction of the full-working-condition heat balance performance is realized, and the high-temperature fault solving efficiency is accelerated.

A multi-piece solid golf ball includes a core, a surrounding layer, an intermediate layer, and a cover, in which a large number of dimples are formed on an outside surface of the cover, a relationship of surface hardnesses of each sphere is specified, an initial velocity of the ball is set to 75.0 to 77.724 m / s, and a relationship of a ratio to a lift coefficient / drag coefficient at a Reynolds number of 218,000 and a spin rate of 2,800 rpm, a lift coefficient / drag coefficient at a Reynolds number of 184,000 and a spin rate of 2,900 rpm, and a lift coefficient / drag coefficient at a Reynolds number of 158,000 and a spin rate of 3,100 rpm is specified.

The invention discloses a ship air sail navigation aiding energy efficiency dynamic optimization method and system and a ship, and relates to the technical field of ship energy conservation. Dynamic parameters in the ship navigation process are collected in real time; establishing a dynamic coupling model; the coupling model is utilized to quantify the dynamic interference of the hull attitude parameters on the air sail state parameters into attack angle offset; a reinforcement learning algorithm is adopted to simulate the attack angle offset, and the optimal attack angle of the air sail is obtained; according to the optimal attack angle and the environmental parameters, target adjustment parameters of the air sail are calculated; and driving the air sail to adjust the sail body rotation angle and the sail surface inclination angle in real time according to the target adjustment parameters. According to the method, the air sails always work in the efficient interval with the maximum lift coefficient and the minimum resistance coefficient, the pneumatic interference model is introduced, the total auxiliary thrust of the multiple sails is improved, the problem that the energy-saving effect is reduced due to dynamic deviation of the attack angle is effectively solved, and the situation that the fuel consumption of a main engine is reduced is stably achieved.

The invention provides a multi-vehicle-type wind resistance coefficient real-time prediction method and system based on vehicle characteristic parameters, and relates to the technical field of vehicle wind resistance coefficient prediction.The method comprises the steps that an original data set containing whole vehicle characteristic parameters and vehicle type labels is obtained, the original data set is processed, and a test set and a non-test set are obtained through division; performing hyper-parameter tuning on the XGBoost model by adopting a Bayesian optimization method and utilizing the non-test set, and determining an approximate optimal hyper-parameter of the XGBoost model; performing optimization again by using a sparrow search algorithm to obtain an optimal hyper-parameter; and carrying out multiple times of training and verification on the optimized XGBoost model, and determining an optimal model so as to carry out wind resistance coefficient prediction. According to the method, high prediction precision can be ensured when wind resistance prediction of different vehicle types is coped, meanwhile, good calculation efficiency is achieved, and the requirements of rapid iteration and real-time prediction are met.

A golf ball is disclosed herein that has at least one modified aerodynamic characteristic or performance trait. More specifically, the golf ball disclosed herein can include a dimple pattern having a specific drag coefficient and / or specific integrated drag area.

A golf ball is disclosed herein that has at least one modified aerodynamic characteristic or performance trait. More specifically, the golf ball disclosed herein can include a dimple pattern having a specific drag coefficient and / or specific integrated drag area.

The application discloses a solid droplet-based drag reduction ball preparation and testing method, and relates to the underwater drag reduction technical field.The preparation method comprises the following steps: performing decontamination treatment on the surface of a steel ball, configuring a PDMS solution and pouring the PDMS solution into a polytetrafluoroethylene mold with small holes with different curvature radii, performing vacuum degassing and solidification, and then peeling off to obtain solid droplet structures with different curvature radii, and bonding the solid droplet structures to the bottom of the steel ball.Through the regulation and control of the solid droplet curvature radius (2.5-10.8 mm) and the water entry speed, the high-speed camera technology is used to observe the change law of the sputtering crown formation, air entrainment and air cavity closure mode in the water entry process, the quantitative analysis of the underwater air cavity volume and the drag coefficient is combined, and the influence of the solid droplet curvature radius on the air cavity shape and the drag reduction performance is verified.The solid droplet structure optimizes the air film capture efficiency, significantly reduces the blunt body pressure difference resistance and the friction resistance, and the preparation process is simple, stable and suitable for the development of the underwater vehicle drag reduction technology.

The present invention belongs to the technical field of development of automatic shift control systems for special vehicles, and specifically relates to a method for estimating the equivalent drag coefficient of special vehicles. The method comprises: extracting features from signals; using the recursive least squares method to identify and estimate the vehicle mass and the equivalent drag coefficient; performing confidence preprocessing on the estimated values; further performing confidence judgment on the credible estimated values ​​screened out; and finally performing weight fusion calculations. The method further reduces the deviation of the estimation results caused by abnormal data and calculation parameter errors, and has high real-time performance. The method for estimating the equivalent drag coefficient of special vehicles has been successfully applied to the calculation and simulation analysis of the control system of a certain wheeled armored vehicle. Verification shows that the method is reasonably designed, has clear logic, and reduces estimation deviations. It can meet the current application and subsequent development needs, and has significant progressive significance for the development of the project.

The application discloses an online identification method for drag coefficient of an interceptor based on artificial intelligence, which utilizes sensors on an aircraft to measure kinematic information of the aircraft and the interceptor in real time, inputs the measured information into an identification model, and obtains the drag coefficient of the interceptor. The online identification method for the drag coefficient of the interceptor based on artificial intelligence has faster identification speed and higher accuracy.

The invention discloses a satellite orbit forecasting method based on in-orbit calibration of model parameters. Belongs to the technical field of remote sensing satellite measurement, operation and control and particularly relates to the technical field of remote sensing satellite orbit forecasting. According to the method, the satellite windward side-to-mass ratio in an atmospheric resistance model is calibrated regularly according to actually measured orbit data, the resistance coefficient in the atmospheric resistance model is calibrated in real time, and more accurate model parameters are used for modeling a perturbative force model in the satellite orbit forecasting process, so that the error of the atmospheric resistance model is reduced, and the orbit forecasting precision is improved. In the time period that the space weather changes gently, the atmospheric resistance modeling precision is improved to 90% or above from about 60%-80% of a traditional method through the method.

The invention discloses an aerodynamic characteristic correction method for a wind turbine airfoil wind tunnel test in the field of wind turbine airfoil aerodynamic characteristic optimization. The method comprises the following steps: 1) constructing a wind turbine airfoil aerodynamic test platform for the wind tunnel test; 2) carrying out safety check on equipment and an experimental environment; (3) measuring the surface pressure of the wind turbine airfoil under the expected working condition by using a high-frequency pressure sensor to obtain a measured pressure signal; 4) performing frequency domain analysis on the pressure signal to obtain the power spectrum density of the pressure signal of the wind turbine airfoil under the expected working condition; 5) estimating and identifying vortex shedding frequency; (6) pressure signal pulsation and measurement errors caused by the vortex are distinguished, a Kalman filter is designed to filter the pressure signals, and corrected pressure signals are obtained; 7) estimating a pressure signal of a specific pressure measuring point position; and 8) calculating to obtain the lift coefficient and the resistance coefficient of the corrected wind turbine airfoil. According to the method, the vortex shedding frequency can be accurately identified, the noise can be effectively filtered, and the correction method of the real aerodynamic coefficient can be obtained.

This invention discloses a method for calculating the fuel consumption saving rate of a vehicle platoon based on topology and dynamic characteristics. The method includes establishing a vehicle dynamics model, an external flow field model, and a mathematical analysis model of the fuel consumption saving rate of the vehicle platoon. The proposed method conducts simulation experiments for different parameters such as longitudinal vehicle spacing, lateral vehicle offset distance, and vehicle speed. By analyzing the influence of longitudinal vehicle spacing, lateral vehicle offset distance, and vehicle speed on the vehicle's aerodynamic drag coefficient, the functional relationship between the vehicle platoon's aerodynamic drag coefficient and the above parameters is determined. Furthermore, the functional relationship between the aerodynamic drag coefficient and the fuel consumption saving rate is determined to calculate the vehicle platoon's fuel consumption saving rate.

The invention discloses a shape-preserving and resistance-reducing design method for a rotating mechanism under rotor / fuselage coupling, which comprises the following steps of: setting the slenderness ratio of a streamline shaft sleeve based on a shape resistance coefficient formula, and verifying the surface pressure distribution and the separation area of the shaft sleeve through numerical simulation to ensure that the shape resistance coefficient meets a resistance-reducing target; setting the area ratio of an outlet to an inlet of the seam based on a Venturi effect formula, so that a low-pressure area is formed in the seam to suck a wing root boundary layer and delay airflow separation; establishing an aerodynamic load and motion parameter coupling model based on an instantaneous resistance formula, analyzing flow fields under different rotation angular velocities and oblique angles through numerical simulation, and optimizing a rotation track to reduce a resistance peak value and aerodynamic torque fluctuation; the invention aims to solve the problems of airflow vortex interference, large shape resistance, high resistance peak and poor aerodynamic stability by optimizing the shape of the rotating shaft sleeve, the fuselage-wing gap structure and the wing rotating track, and improves the cruise fuel efficiency and flight stability of the aircraft.

This invention relates to the field of in-situ testing of plant airflow resistance characteristics, and provides a suitable in-situ testing method for plant airflow resistance characteristics. It employs a portable, quick-assembly in-situ DC wind tunnel in conjunction with a handheld anemometer and anemometer. The DC wind tunnel consists of a portable bed-type lifting frame and a wind tunnel device mounted on it, allowing for free adjustment of the test support platform's ground clearance, thus enabling flexible adjustment of the wind tunnel body, i.e., the height of the test port. Using this DC wind tunnel structure, the wind field at any wind speed can be reproduced by adjusting the variable frequency fan in the power section. Combined with the handheld anemometer and anemometer, the wind speed and pressure values ​​before and after the plant are measured. The average value of each measuring point before and after is taken as the final measured wind speed and pressure value. Based on the measured pressure drop and wind speed, the drag coefficient at different heights of the plant is calculated, thereby enabling in-situ testing of the plant's aerodynamic resistance characteristics at different heights and wind speeds.