221 research outputs found

    Determination of the Wind Speed and Direction by Means of Fluidic-Domain Signal Processing

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    This paper presents an analytical model for a recently introduced class of 2-D directional anemometers based on fluidic structures capable of averaging the differential pressure developed by the wind across distinct diameters of the transverse cross-section of a single cylinder. In previous works, it was found that performing the average over a proper set of diameters produces a differential pressure that depends on the wind direction according to a cosine law, allowing simple direction estimation. This fact, which was not investigated in previous articles, is explained in this paper taking into account symmetry and angular spectral properties of the pressure distribution. Besides analyzing previously proposed devices, this paper introduces several new configurations, which are classified according to the type of average and number of diameters involved. Comparison of the estimated performances with the experimental results obtained in earlier works clearly shows that prototypes proposed so far were far from achieving the best theoretical accuracy, suggesting that significant improvements can be obtained by re-design of the fluidic structures

    Three-Axis’ Heat Loss Anemometer Comprising Thick-Film Segmented Thermistors

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    NTC thick-film segmented thermistors were used as anemometer sensing devices. They were screen printed of thick-film thermistor paste based on modified NiMn2O4 fine powder, organic vehicle, and glass frit. Their electrical properties, such as resistance vs. temperature R(T) and thermistor exponential factor B were obtained using measurements in the climatic test chamber. A uniaxial anemometer was formed using a thick-film segmented thermistor, which was placed in the hole drilled in rectangular piece of thermally insulating material. The uniaxial anemometer was used for the optimization of operating point of segmented thermistors as self-heating/wind sensing devices. The dc supply voltage was correlated with the air temperature sub-ranges (RCV). The power save mode such as 30s self-heating/5 min pause was used to measure the thermistor response on stable wind blow. The three-axis' anemometer was formed using five sensor devices placed in five holes drilled in the cubical piece of thermally insulating material: three thermistor sensors measure wind speed on the x, y, z - axes, the fourth sensor Pt 1000 measures the air temperature T, while the fifth sensor (capacitive type) measures humidity H. The obtained sensitivity and inaccuracy were compared with respective ones of other anemometers

    Development of an Airflow Monitoring System for Air Handling Unit using IoT

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    This paper presents the development of an airflow monitoring system for air handling units using NodeMCU ESP32. The main purpose of this project is to improvise the use of microcontroller with on-par performance for industrial applications. This proposed system consists of two sensors that measure airflow from the air handling unit. The first sensor is an airflow speed, which measures the airflow speed from the air handling unit. The second sensor detects and indicates the temperature and humidity of the airflow. The testing parameters show very good correlations among variables, indicating the efficiency of the system to monitor the airflow. Keywords: Airflow, IoT, Temperature, Humidity, Air Handling Unit eISSN: 2398-4287 © 2022. The Authors. Published for AMER ABRA cE-Bs by E-International Publishing House, Ltd., UK. This is an open-access article under the CC  BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under the responsibility of AMER (Association of Malaysian Environment-Behavior Researchers), ABRA (Association of Behavioral Researchers on Asians), and cE-Bs (Centre for Environment-Behavior Studies), Faculty of Architecture, Planning & Surveying, Universiti Teknologi MARA, Malaysia

    Effects of motion on jet exhaust noise from aircraft

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    The various problems involved in the evaluation of the jet noise field prevailing between an observer on the ground and an aircraft in flight in a typical takeoff or landing approach pattern were studied. Areas examined include: (1) literature survey and preliminary investigation, (2) propagation effects, (3) source alteration effects, and (4) investigation of verification techniques. Sixteen problem areas were identified and studied. Six follow-up programs were recommended for further work. The results and the proposed follow-on programs provide a practical general technique for predicting flyover jet noise for conventional jet nozzles

    A Marine Radar Wind Sensor

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    A new method for retrieving the wind vector from radar-image sequences is presented. This method, called WiRAR, uses a marine X-band radar to analyze the backscatter of the ocean surface in space and time with respect to surface winds. Wind direction is found using wind-induced streaks, which are very well aligned with the mean surface wind direction and have a typical spacing above 50 m. Wind speeds are derived using a neural network by parameterizing the relationship between the wind vector and the normalized radar cross section (NRCS). To improve performance, it is also considered how the NRCS depends on sea state and atmospheric parameters such as air–sea temperature and humidity. Since the signal-to-noise ratio in the radar sequences is directly related to the significant wave height, this ratio is used to obtain sea state parameters. All radar datasets were acquired in the German Bight of the North Sea from the research platform FINO-I, which provides environmental data such as wind measurements at different heights, sea state, air–sea temperatures, humidity, and other meteorological and oceanographic parameters. The radar-image sequences were recorded by a marine X-band radar installed aboard FINO-I, which operates at grazing incidence and horizontal polarization in transmit and receive. For validation WiRAR is applied to the radar data and compared to the in situ wind measurements from FINO-I. The comparison of wind directions resulted in a correlation coefficient of 0.99 with a standard deviation of 12.8°, and that of wind speeds resulted in a correlation coefficient of 0.99 with a standard deviation of 0.41 m s^−1. In contrast to traditional offshore wind sensors, the retrieval of the wind vector from the NRCS of the ocean surface makes the system independent of the sensors’ motion and installation height as well as the effects due to platform-induced turbulence

    3D Simulation of the Velodyne HDL-32E Lidar Integrated with an Autonomous Marine Vehicle

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    A 3D simulator is programmed for modeling the Velodyne HDL-32E LIDAR used on the WAM-V vehicle in the marine environment for obstacle detection. The model takes into account sensor integration, sensor error, and error correction. Theoretical analysis includes consideration of atmospheric refraction, time of flight error, UDP packet and timing, calibration parameter errors, depth spread error, field of view, accuracy, angular resolution, and points per second in the environment. The average distance error shows a variance of a 0.0127 m to 0.8128 m depending on the laser and the distance. Test results produce distance correction equations for each laser beam. For presented example Laser 1, the error between the corrected values and the actual distance values ranges from .02%-1.14%, which is reduced from the uncorrected error ranging from 1.32% to 3.42%. For all 32 Lasers, the real-world uncorrected distance readings have a deviation of -1.02E-05 σ to .171σ, where σ= 0.0221 m when the Red Taylor Buoy is at .518 m. The corrected distance readings deviate from 1.43E-07σ to 0.0931σ. The simulated uncorrected distance readings deviate from -0.411σ to 2.77σ, with σ= 0.0208 m. The corrected distance readings in simulation deviate from the standard by -.218σ to 2.24σ. The field of view is measured to be 41 degrees. Reflectivity and intensity profiles are presented. Physical textures are also generated based on these profiles from buoy obstacles used in the marine competition tasks. By color, the increasing order of intensity for obstacles is black, green, red, and then white. The final product consists of data used for simulation of the Velodyne HDL-32E and reporting the accuracy of simulated physical values relative to the real world testing

    Improved HVAC energy throughput system

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    Currently heating, ventilation and air conditioning (HVAC) systems are difficult and costly to monitor for energy efficiency performance and reliability. As buildings evolve, they will require higher levels of insulation and air tightness which will require ventilation systems to provide the minimum number of air changes and reduced energy usage by recovering heat from the air before it is expelled. This will necessitate the need for monitoring of the operating performance of these systems so that air quality or building energy efficiency is not detrimentally affected. A typical duct airflow monitoring device uses a pressure differential method to determine the airflow rate but they are fragile, expensive and create an additional pressure loss. The monitoring of airflow rates can indicate problems in the design, installation and operation of a HVAC system. One of the possible alternatives to using pressure differential type devices such as Pitot tube/arrays, orifice plates and Venturis is to use an ultrasonic flow rate sensor, but historically their high cost has restricted their use in HVAC systems. This project has looked at improving on existing measuring systems by developing an ultrasonic in-duct flowmeter system to measure the mean airflow, temperature and humidity of a ventilation duct so that a comparative energy level can be accurately deduced. A proof of concept in-duct ultrasonic airflow monitoring device has been developed and has obtained results within ±3.5% RMS of a Venturi airflow measuring device. Matlab code for a Monte Carlo acoustic ray/particle tracing ultrasonic flowmeter simulation has been developed to study the effects of non-ideal installation scenarios. The fully developed centreline computational fluid dynamics (CFD) mean flow velocity to duct total mean flow velocity error can be up to 13%. Analysis of the CFD data for various duct scenarios has shown that this could be reduced to below 5% by using a transducer offset of approximately ±0.25 duct diameters or widths from the centreline at distances as close as one duct hydraulic diameter from an upstream disturbance, such as caused by a bend

    An Experimental Investigation of Wind Turbine Aerodynamic Interaction

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    Wind turbines have become a viable component in the overall energy makeup of the United States due to improved economics where energy prices have risen and production costs dropped. For a fixed cost, the effectiveness of a wind turbine financially is highly related to its performance. Considering the size of current wind farms, a minor performance improvement will result in large additional sums of revenue. A problem that has received attention with wind farms is that while the fixed costs of the development do get spread out further to reduce the installed cost of each wind turbine, the wind turbines have been observed to perform at lower performance values in the wind farm setting. Development work is performed to predict maximum theoretical levels of performance describing a wind turbine. This work is extended to include predictions of the limiting power for a two-rotor, counter-rotating wind turbine configuration. Wind farm performance losses are also modeled for the dominant modes of interaction when operating a wind turbine within the wake of upstream machines; covering single-, multiple-, and lateral-wake scenarios. A year\u27s worth of wind speed data are analyzed to reveal seasonal trends of the wind turbine input condition. Wind turbine performance is simulated using this data and compared amongst small and large wind turbines. Predictions of wind farm wake models are compared to data generated using the Purdue University Micro Reconfigurable Wind Farm facility. This facility contains four small wind turbines in an in-field experimental setting where wake scenarios are created and performance comparisons measured. Model validation is obtained using the experimental results which provides insight into the model\u27s assumptions\u27 range of effectiveness, and resultant predicted wake behavior. The physical mechanisms of wake operation power losses are also observed from the data showing the relative contribution of the wake loss constituents in different wind farm configurations

    Incorporating field wind data to improve crop evapotranspiration parameterization in heterogeneous regions

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    Accurate parameterization of reference evapotranspiration ( ET0) is necessary for optimizing irrigation scheduling and avoiding costs associated with over-irrigation (water expense, loss of water productivity, energy costs, and pollution) or with under-irrigation (crop stress and suboptimal yields or quality). ET0 is often estimated using the FAO-56 method with meteorological data gathered over a reference surface, usually short grass. However, the density of suitable ET0 stations is often low relative to the microclimatic variability of many arid and semi-arid regions, leading to a potentially inaccurate ET0 for irrigation scheduling. In this study, we investigated multiple ET0 products from six meteorological stations, a satellite ET0 product, and integration (merger) of two stations’ data in Southern California, USA. We evaluated ET0 against lysimetric ET observations from two lysimeter systems (weighing and volumetric) and two crops (wine grapes and Jerusalem artichoke) by calculating crop ET ( ETc) using crop coefficients for the lysimetric crops with the different ET0. ETc calculated with ET0 products that incorporated field-specific wind speed had closer agreement with lysimetric ET, with RMSE reduced by 36 and 45% for grape and Jerusalem artichoke, respectively, with on-field anemometer data compared to wind data from the nearest station. The results indicate the potential importance of on-site meteorological sensors for ET0 parameterization; particularly where microclimates are highly variable and/or irrigation water is expensive or scarce
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