Vibrations and Waterborne Noise on Fishery Vessels

1988 ◽  
Vol 32 (02) ◽  
pp. 112-133
Author(s):  
W. Ojak
Keyword(s):  
United Nations ◽  
Noise Generation ◽  
Noise Levels ◽  
Structural Vibrations ◽  
Mechanical Vibrations ◽  
Noise Propagation ◽  
Research Institutes ◽  
Fishery Research ◽  
Elastically Supported ◽  
Agricultural Organization

The Food and Agricultural Organization of the United Nations granted a fellowship to the author to study, at several European ship research institutes, the problem of noise generation and propagation on fishery vessels. He later took part in the design of the fishery research vessel Prof. Siedlecki, which included the implementation of a series of antivibration and antinoise precautions. This paper compares vibration and noise levels on two fishery research vessels—the conventional RV G.O.Sars and RV Prof. Siedlecki. The paper is divided into two parts. In the first part, mechanical vibrations of the elastically supported propeller are dealt with and conditions for minimum vibration response are determined. In the second part, structural vibrations in the ships and noise propagation from the ships to the water are described. The paper concludes with data on structural vibrations and waterborne noise propagation. This paper, and the paper published in the June 1984 issue of JOURNAL OF SHIP RESEARCH [1],2 completes the author's approach to propeller vibrations.

scholarly journals RESEARCH AND EVALUATION OF KART NOISE SPREAD INTO THE LIVING ENVIRONMENT / GOKARTŲ KELIAMO TRIUKŠMO SKLAIDOS Į GYVENAMĄJĄ APLINKĄ TYRIMAI IR VERTINIMAS

2014 ◽  
Vol 6 (4) ◽  
pp. 356-361
Author(s):  
Giedrius Juozaponis ◽  
Raimondas Grubliauskas
Keyword(s):  
Wind Speed ◽  
Experimental Studies ◽  
Soil Surface ◽  
Sound Level ◽  
Living Environment ◽  
Noise Levels ◽  
Noise Propagation ◽  
Soil Surface Temperature ◽  
Service Data ◽  
Living Area

The paper examines kart noise propagation in the living environment and sought measures for suppressing it. To conduct experimental studies, precision sound level analyzer Bruel & Kjaer 2260th has been used. In cooperation with the Lithuanian Hydrometeorological Service, data on relative humidity, wind speed and direction, soil surface temperature and air temperature have been applied. According to the Lithuanian Hygiene Standard HN 33:2011 Noise Thresholds in Residential and Public Buildings and Their Environment, the areas with an elevated noise level are identified thus selecting noise reduction measures aimed at reducing noise levels up to the permitted ones. The analysis of the obtained results has focused on the regularities between noise propagation and meteorological events and their impact on the spread of noise. The environmental factors more or less influencing the climate and noise spread in the living area have been determined. With reference to the received information, the ways to reduce noise have been suggested. Straipsnyje nagrinėjamas gokartų keliamo triukšmo sklidimas į gyvenamąją aplinką ir ieškoma priemonių jam slopinti. Eksperimentiniams tyrimams atlikti buvo naudojamas precizinis garso lygio analizatorius „Bruel&Kjaer 2260“. Bendradarbiaujant su Lietuvos hidrometeorologijos tarnyba panaudoti santykinės oro drėgmės, vėjo stiprumo ir krypties, dirvožemio paviršiaus temperatūros bei oro temperatūros duomenys. Vadovaujantis Lietuvos higienos normomis HN 33:2011 „Triukšmo ribiniai dydžiai gyvenamuosiuose ir visuomeninės paskirties pastatuose bei jų aplinkoje“ nustatomos zonos, kuriose triukšmo lygis yra viršijamas, ir parenkant triukšmo mažinimo priemones siekiama triukšmą sumažinti iki leidžiamųjų normų. Gautų rezultatų analizės metu ieškoma dėsningumų tarp triukšmo sklidimo ir meteorologinių reiškinių bei jų daroma įtaka triukšmo plitimui. Nustatomi aplinkos klimato veiksniai, darantys įtaką ar mažiau veikiantys triukšmo sklaidą gyvenamojoje teritorijoje. Atsižvelgiant į gautus rezultatus siūlomi triukšmo mažinimo būdai.

On the Modelling of Noise Generation in Corrugated Pipes

2009 ◽  
Author(s):  
Hugh Goyder
Keyword(s):  
Vortex Shedding ◽  
Oil And Gas ◽  
Natural Frequencies ◽  
Oil And Gas Industry ◽  
Noise Generation ◽  
Noise Levels ◽  
Eigenvalue Approach ◽  
Gas Industry ◽  
Offshore Oil And Gas ◽  
Offshore Oil

The offshore oil and gas industry uses pipes which are made flexible by means of a corrugated construction. Those pipes that run from a platform to the seabed are known as risers while those that connect two pipes on the seabed are known as jumpers. Gas flowing within the pipe interacts with the corrugations and generates noise. This noise is of concern because it is of sufficient amplitude to cause pipework vibration with the threat of fatigue and pipe breakages. This paper examines the conditions that give rise to the large noise levels. The conditions for the onset of noise are investigated using an eigenvalue approach which involves the effect of damping due to losses from the pipe boundaries and pipe friction. The investigation which is conducted in terms of reflection conditions shows why only few of the very many possible natural frequencies are selected. The conditions for maximum noise response are also investigated using a non-linear model of vortex shedding. Here an approach is developed in which the net power generated along a single wavelength is calculated.

On the Modelling of Noise Generation in Corrugated Pipes

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Hugh Goyder
Keyword(s):  
Vortex Shedding ◽  
Oil And Gas ◽  
Natural Frequencies ◽  
Oil And Gas Industry ◽  
Noise Generation ◽  
Noise Levels ◽  
Eigenvalue Approach ◽  
Gas Industry ◽  
Offshore Oil And Gas ◽  
Offshore Oil

The offshore oil and gas industry uses corrugated pipes because of their flexibility. Gas flowing within these pipes interacts with the corrugations and generates noise. This noise is of concern because it is of sufficient amplitude to cause pipework vibration with the threat of fatigue and pipe breakages. This paper examines the conditions that give rise to the large noise levels. These conditions, for the occurrence of noise, are investigated using an eigenvalue approach, which involves the effect of damping due to losses from the pipe boundaries and pipe friction. The investigation is conducted in terms of reflection conditions and shows why only few of the very many possible natural frequencies are selected. The conditions for maximum noise response are also investigated by means of a nonlinear model of vortex shedding. Here, an approach is developed in which the net power generated by each wavelength is calculated.

scholarly journals Estimation of evapotranspiration by the Food and Agricultural Organization of the United Nations (FAO) Penman–Monteith temperature (PMT) and Hargreaves–Samani (HS) models under temporal and spatial criteria – a case study in Duero basin (Spain)

2020 ◽  
Vol 20 (3) ◽  
pp. 859-875 ◽  
Author(s):  
Rubén Moratiel ◽  
Raquel Bravo ◽  
Antonio Saa ◽  
Ana M. Tarquis ◽  
Javier Almorox
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
United Nations ◽  
Irrigated Agriculture ◽  
Arid Zones ◽  
Empirical Coefficient ◽  
Minimum Relative Humidity ◽  
Duero Basin ◽  
The United Nations ◽  
Agricultural Organization

Abstract. The evapotranspiration-based scheduling method is the most common method for irrigation programming in agriculture. There is no doubt that the estimation of the reference evapotranspiration (ETo) is a key factor in irrigated agriculture. However, the high cost and maintenance of agrometeorological stations and high number of sensors required to estimate it make it non-plausible, especially in rural areas. For this reason, the estimation of ETo using air temperature, in places where wind speed, solar radiation and air humidity data are not readily available, is particularly attractive. A daily data record of 49 stations distributed over Duero basin (Spain), for the period 2000–2018, was used for estimation of ETo based on seven models against Penman–Monteith (PM) FAO 56 (FAO – Food and Agricultural Organization of the United Nations) from a temporal (annual or seasonal) and spatial perspective. Two Hargreaves–Samani (HS) models, with and without calibration, and five Penman–Monteith temperature (PMT) models were used in this study. The results show that the models' performance changes considerably, depending on whether the scale is annual or seasonal. The performance of the seven models was acceptable from an annual perspective (R2>0.91, NSE > 0.88, MAE < 0.52 and RMSE < 0.69 mm d−1; NSE – Nash–Sutcliffe model efficiency; MAE – mean absolute error; RMSE – root-mean-square error). For winter, no model showed good performance. In the rest of the seasons, the models with the best performance were the following three models: PMTCUH (Penman–Monteith temperature with calibration of Hargreaves empirical coefficient – kRS, average monthly value of wind speed, and average monthly value of maximum and minimum relative humidity), HSC (Hargreaves–Samani with calibration of kRS) and PMTOUH (Penman–Monteith temperature without calibration of kRS, average monthly value of wind speed and average monthly value of maximum and minimum relative humidity). The HSC model presents a calibration of the Hargreaves empirical coefficient (kRS). In the PMTCUH model, kRS was calibrated and average monthly values were used for wind speed and maximum and minimum relative humidity. Finally, the PMTOUH model is like the PMTCUH model except that kRS was not calibrated. These results are very useful for adopting appropriate measures for efficient water management, especially in the intensive agriculture in semi-arid zones, under the limitation of agrometeorological data.

scholarly journals Wall-Resolved LES Modeling of a Wind Turbine Airfoil at Different Angles of Attack

2020 ◽  
Vol 8 (3) ◽  
pp. 212 ◽  
Author(s):  
Irene Solís-Gallego ◽  
Katia María Argüelles Díaz ◽  
Jesús Manuel Fernández Oro ◽  
Sandra Velarde-Suárez
Keyword(s):  
Boundary Layer ◽  
Wind Turbine ◽  
Acoustic Waves ◽  
Urban Environments ◽  
Far Field ◽  
Noise Generation ◽  
Noise Propagation ◽  
Trailing Edge ◽  
Wind Turbine Airfoil ◽  
Les Model

Noise has arisen as one of the main restrictions for the deployment of wind turbines in urban environments or in sensitive ecosystems like oceans for offshore and coastal applications. An LES model, adequately planned and resolved, is useful to describe the noise generation mechanisms in wind turbine airfoils. In this work, a wall-resolved LES model of the turbulent flow around a typical wind turbine airfoil is presented and described in detail. The numerical results obtained have been validated with hot wire measurements in a wind tunnel. The description of the boundary layer over the airfoil provides an insight into the main noise generation mechanism, which is known to be the scattering of the vortical disturbances in the boundary layer into acoustic waves at the airfoil trailing edge. In the present case, 2D wave instabilities are observed in both suction and pressure sides, but these perturbations are diffused into a turbulent boundary layer prior to the airfoil trailing edge, so tonal noise components are not expected in the far-field noise propagation. The results obtained can be used as input data for the prediction of noise propagation to the far-field using a hybrid aeroacoustic model.

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