Search Results (17)

The foundational element of any ventilation system assessment is the precise definition of the primary airflow intake. In underground mine networks, even a marginal error in primary inputs triggers a series of inaccuracies, resulting in significant volumetric errors across the entire network. This study explores the sensitivity of the iterative Hardy Cross algorithm for ventilation network analysis towards the main intake, and demonstrates that the intake overestimation error reaches 77%, creating a false sense of security. Furthermore, when utilizing the Hardy Cross approach, evaluating a model based solely on its mathematical tendency to balance is misleading; analysis of relative error evolution demonstrates that a converged network can achieve mathematical balance while remaining fundamentally uncoupled from the mine’s physical reality due to flawed input data. While technical fields currently diverge into two primary paths for airflow definition, overly simplistic approximations or specialist-dependent numerical CFD models, this study proposes a middle ground alternative. The proposed methodology relies on direct anemometric field measurements synthesized through cartographic mapping integration techniques. The suggested technique offers a detailed graphical representation of air velocity across the excavation, derived from the isovel mapping. This visualization illustrates that airflow behaviour through rock excavations is fundamentally non-uniform and dictated by wall roughness and structural irregularities. Full article

The increasing share of wind power generation has intensified the occurrence of curtailment events in power systems worldwide, mainly driven by transmission constraints, operational limitations, and imbalances between generation and demand. In the Brazilian context, this phenomenon has become more pronounced since 2023, highlighting structural challenges of the Brazilian Interconnected Power System and the need for reliable methodologies to estimate curtailed wind generation. This study presents a methodology to estimate wind power potential during curtailment events, aiming to support forecasting models and the economic compensation of affected generating agents. The proposed approach integrates measured power generation data, technical information of wind farms, and anemometric measurements from SCADA systems, combining data filtering and consistency procedures, gap-filling based on spatial correlation among wind farms, and regression models supported by statistical and computational techniques for wind-to-power conversion. The methodology was applied to more than 1000 wind farms connected to the Brazilian transmission grid and achieved accuracy levels above 95% on a semi-hourly basis and exceeding 99% for annual aggregations. Full article

The field deployment of low-cost air quality sensor systems enables enhanced spatial resolution in air quality monitoring. Although these sensor systems cannot achieve the same accuracy as regulatory monitoring stations, they can attain acceptable levels of confidence and provide Indicative Measurements as regulated by Ambient Air Quality EU Directive. The integration of an anemometer into a system can provide additional information for the classification of the measurement area, the identification of potential sources of pollutant emissions, and the assessment of the device’s operating conditions during measurement. In this study, the measurement capabilities of an Airbox, a low-cost air quality sensor system, were extended through the integration of a DW6410 anemometer (Davis Instruments). The Airbox, designed to transmit data in real-time or near real-time to servers and IoT platforms, was deployed for a duration of 4 months, from October 2021 to February 2022, within the airport area of Grottaglie (Southern Italy). The anemometric measurements and particulate concentration data (PM_2.5 and PM₁₀, measured by NextPM sensor, Tera Sensor) were integrated and compared to meteorological open data and data from a regulatory regional air quality control network located in the area around the airport. Full article

Northeastern Brazil (NEB) has a high potential for wind energy generation, making it a strategic area for the development of this renewable source. However, the region’s complex wind regime, driven by interactions between large-scale atmospheric systems, local circulations, and coastal topography, presents significant challenges for weather forecasting and wind energy applications. Despite this, detailed assessments of forecast performance using mesoscale models remain limited. The main objective was to develop an efficient strategy that enables satisfactory results by optimizing data assimilation, land use and topography information as well as improvements in physical parameterizations and post-processing, optimizing computational effort. Forecasting conducted during the year 2020 were validated with data from 20 anemometric measurement towers (AMTs), located at strategic points across various wind power complexes. The model’s performance was evaluated using statistical metrics such as MBE, MAE, nRMSE, standard deviation ratio, and correlation. Additionally, the impact of bias removal was assessed using two approaches: one that eliminates the mean error per forecasted time step and another employing artificial intelligence for bias removal training. The results revealed distinct characteristics for each analyzed location, with errors of diverse nature due to the local nuances of the measurements. However, both bias removal approaches showed significant improvements in wind characterization across all complexes. Full article

This article presents an overview of airflow velocity measurement methods applied to renewable energy. Basic measurement methods used in this field are discussed: tachometric, ultrasonic, and calorimetric anemometry. The principle of operation and basic properties of anemometers are presented, and based on publications from the last decade, a systematic review of development directions and trends in this field is made. The aim of the article is to familiarize people dealing with renewable energy problems, in particular wind energy, with the current state of knowledge in the field of anemometric measurements, properties of individual types of measuring devices, as well as directions of development of measurement tools. This will allow for the optimization of processes in the field of wind energy, in particular in the selection of the location of the energy facility, implementation of investments and control, diagnostics, and monitoring during operation. The selection of metrological tools adequate to the problem also allows for ensuring an appropriate level of work safety and environmental and ecological harmony and supporting the process of sustainable development. Full article

We conducted an experiment comparing wind speeds and aerodynamic roughness length (z₀) values over three snow surface conditions, including a flat smooth surface, a wavy smooth surface, and a wavy surface with fresh snow added, using the wind simulation tunnel at the Shinjo Cryospheric Laboratory in Shinjo, Japan. The results indicate that the measurement location impacts the computed z₀ values up to a certain measurement height. When we created small (4 cm high) snow bedforms as waves with a 50 cm period, the computed z₀ values varied by up to 35% based on the horizontal sampling location over the wave (furrow versus trough). These computed z₀ values for the smooth snow waves were not significantly different than those for the smooth flat snow surface. Fresh snow was then blown over the snow waves. Here, for three of four horizontal sampling locations, the computed z₀ values were significantly different over the fresh snow-covered waves as compared to those over the smooth snow waves. Since meteorological stations are usually established over flat land surfaces, a smooth snow surface texture may seem to be an appropriate assumption when calculating z₀, but the snowpack surface can vary substantially in space and time. Therefore, the nature of the snow surface geometry should be considered variable when estimating a z₀ value, especially for modeling purposes. Full article

The aim of the paper is to validate the analytical–numerical analysis method regarding the operating regime of the propellers of a quadcopter. The research aims to mark the flow areas whose numerical results differ from the experimental ones and to investigate the possible reasons for the discrepancies between the values. The paper presents the determination of the air velocity produced by the rotational movement of a quadcopter propeller for a stationary position of the drive motor. The velocities were determined both experimentally at various points located below the propeller plane using hot-wire anemometric probes and numerically using a time-lapse simulation with a rotating sliding table. The numerical simulations carried out consisted of the determination of the time variation of the velocity distribution developed by the propeller in the rotational movement for the different operating (power) cycles of the engine. In addition, a technique that utilizes reverse engineering to determine the propeller profile, the anemometric probe calibration, and the average velocity values measured at various points below the propeller plane for engine operating regimes that range from 60 to 90% are also presented. Full article

One of the most common problems in wind resource assessment is that measured data are not always available at the site of interest. That is why, in several studies, reanalysis data have been used as an alternative, which, in some cases, have been validated by measured data. Mexico is no exception, since there are not many measurement towers in the country that provide valid records throughout the country. In view of the above, in this study a comparison was made between the measurements observed in six anemometric towers, located in different locations in the United Mexican States; data from the MERRA-2 and ERA-5 reanalysis; and data from the generalized wind climates (GWC), available in the Global Wind Atlas. The study was conducted at 80 m, which is the highest height at which data were recorded on the measurement towers at each site. In the case of the MERRA-2 and ERA-5 data, extrapolation of the data series to 80 m was required. In the case of the towers, a comparison of the two data sets measured at 80 m and the height at which two anemometers were available, was performed. This analysis was supported by Windographer version 4 software designed by the company UL solutions, from which *.tab files were exported at 80 m, which were then imported from the WAsP 10.0 program to perform the microscale modeling. The comparison variable was the mean power density, for which the relative deviations between the measured values and those obtained from the reanalysis data and the GWCs were determined. For a better interpretation of the relative errors calculated, an analysis of the orographic characteristics of all the sites was performed using the roughness index (RIX). The results obtained showed that the behavior of the reanalysis and the GWC data was not homogeneous in the sites studied; therefore, an adequate relationship between the magnitudes of the ΔRIX and the relative deviations was not observed, especially for the ERA5 and GWC. The ERA5 data were the furthest from the measured data, with relative deviations greater than 50% at five of the six sites; however, the MERRA-2 and GWC data were the closest to the measured data. The MERRA-2 data showed deviations of less than 11%, except at the La Venta site, where it was 29.5%—a site where the GWC also had a high deviation of 139.4%. The latter is attributable to the effects caused by the nearby wind farms on the wind flow measured by the La Venta station. In general, the MERRA-2 data are an alternative to performing a pre-analysis of the wind resource in Mexico. Full article

Hot-wire anemometric measurements are often related to the determination of flow parameters in a high frequency range. Such knowledge is particularly important when analyzing the flow phenomena in the vicinity of wind turbines. The reliability of obtained results is determined by the knowledge of the properties of the system used for measurements. It concerns both the static and dynamic characteristics of individual measurement channels. In studies of hot-wire anemometric systems, a problem related to the unstable transmission bands of such systems and their high dependence on measurement conditions and the system configuration itself has been commonly indicated. This paper presents the results of an investigation of a new type of hot-wire anemometer, allowing for automatic adjustment of its dynamic characteristics under real working conditions. The presented system is dedicated to the analysis of the wind energy spectrum in experimental laboratory tests on reduced-scale models and to specialized in situ measurements. Full article

Downburst winds are strong downdrafts of cold air that embed into the atmospheric boundary layer (ABL) and produce intense horizontal outflow upon impingement on the ground. They are highly transient and three-dimensional extreme wind phenomena with a limited spatiotemporal structure that often makes the anemometric measurements in nature inadequate for reconstructing their complex flow fields. In the framework of the project THUNDERR, an experimental campaign on downburst outflows has been carried out at the WindEEE Dome at Western University, Canada. The present study analyzes the three-dimensional interaction between downburst (DB) outflows produced as large-scale impinging jets and ABL winds. Most experimental, numerical and analytical models in the literature neglect this flow interplay or treat it in an oversimplistic manner through a vector superposition. We found that the generated near-surface outflow is asymmetric, and a high-intensity wind zone develops at the interface between DB and ABL winds. The time variability of the leading edge of the outflow was investigated by synchronizing all wind measurements across the testing chamber. The three-dimensional flow structure was studied using a refined grid of Cobra probes that sampled the flow at high frequencies. The passage of the primary vortex produced a significant decrease in the height of maximum radial wind speed, predominantly in the ABL-streamwise direction. The turbulence intensity was the highest in the region where DB propagates into oppositely directed ABL winds. Full article

The conditions for the occurrence of high waves in front of the Rijeka port in the Rijeka Bay were analyzed. The analysis was carried out on the basis of measured data on the wave rider station located in front of the main breakwater of the port of Rijeka and the results of numerical wave generation modelings for the wider sea area on the spatial scale of the Adriatic basin. The results of the conducted analysis show that the sudden transition in wind direction from the third to the second quadrant (and vice versa), with the simultaneous rapid increase in wind speed, creates the conditions for generating the largest waves in front of the port of Rijeka. The main reason for achieving the highest wave height in these conditions is the unbalanced wind power input with non-developed surface dissipation (white-capping) and quadruplet wave interaction. Situations with a slower increase in wind speed and approximately constant wind direction resulted in the occurrence of smaller wave heights. The direct application of anemometric data for the forcing wind field in the Adriatic basin within the wave generation model results in a more accurate simulation of wave height and wave period development than application of the wind field from the prediction atmospheric model Aladin-Hr. This is due to the fact that the site is located in a semi-enclosed sea area of restricted fetch, and the spatial/temporal resolution of atmospheric data (2 km and 3 h) is not sufficient to resolve the rapid transition in the wind field. In the case of direct application of anemometric data, the white-capping parameterization should be of a non-stationary character. Full article

This work assessed the quality of wind speed estimates in Uruguay. These estimates were obtained using the Weather Research and Forecast Model Data Assimilation System (WRF-DA) to assimilate wind speed measurements from 100 m above the ground at two wind farms. The quality of the estimates was assessed with an anemometric station placed between the wind farms. The wind speed estimates showed low systematic errors at heights of 87 and 36 m above the ground. At both levels, the standard deviation of the total errors was approximately 25% of the mean observed speed. These results suggested that the estimates obtained could be of sufficient quality to be useful in various applications. The assimilation process proved to be effective, spreading the observational gain obtained at the wind farms to lower elevations than those at which the assimilated measurements were taken. The smooth topography of Uruguay might have contributed to the relatively good quality of the obtained wind estimates, although the data of only two stations were assimilated, and the resolution of the regional atmospheric simulations employed was relatively low. Full article

When applied to a snow-covered surface, aerodynamic roughness length, z₀, is typically considered as a static parameter within energy balance equations. However, field observations show that z₀ changes spatially and temporally, and thus z₀ incorporated as a dynamic parameter may greatly improve models. To evaluate methods for characterizing snow surface roughness, we compared concurrent estimates of z₀ based on (1) terrestrial light detection and ranging derived surface geometry of the snowpack surface (geometric, z_0G) and (2) vertical wind profile measurements (anemometric, z_0A). The value of z_0G was computed from Lettau’s equation and underestimated z_0A but compared well when scaled by a factor of 2.34. The Counihan method for computing z_0G was found to be unsuitable for estimating z₀ on a snow surface. During snowpack accumulation in early winter, z₀ varied as a function of the snow-covered area (SCA). Our results show that as the SCA increases, z₀ decreases, indicating there is a topographic influence on this relation. Full article

In this work, the authors propose a novel directional anemometric system, showing a compact design and the absence of external mechanical moving parts. The measuring principle is based on a dual channel spherical wind conveyor structure, combined with a pressure difference sensing technique of the conveyed air flows by the employment of electromagnetic inductive transducers. Full article

A thermo-anemometric flowmeter design and the principles of its work are presented in the article. A mathematical model of the temperature field in a stream of biofuel is proposed. This model allows one to determine the fuel consumption with high accuracy. Numerical modeling of the heater heat balance in the fuel flow of a thermo-anemometric flowmeter is conducted and the results are analyzed. Methods for increasing the measurement speed and accuracy of a thermo-anemometric flowmeter are proposed. Full article