Speed Regime Research Articles

Methods of Maintaining Soil Depth Evenness During Disk Tillage

Abstract The article examines agro-technical requirements of machine implements with disk working bodies and is aimed to investigate the existing and alternative methods of depth regulation during soil tillage by the mentioned implements. We defined the machines performance indicators significantly affecting the plant potential release not considered previously. The study results were obtained via the soil tilling depth regulation by the disking speed, the change of an incidence angle of the working batteries, and by the use of the additional load mounted on the machine frame. The article presents a two-year research results obtained in 40 different land plots of the Sumy region (Ukraine) using domestic and imported machines, with wheat and buckwheat as crops. To ensure the study accuracy, the methodology was based on the CND 46.16.02.-96. Agricultural Machinery. Quality Indicators Nomenclature (Catalogue of Normative Documents, published in 1997). The research results demonstrate that the tilling depth depends on the manufacturing plant default settings, the speed regime, and the machine load. For the experimental data analysis, the Least Squares Means method was used. The research presents alternative methods of changing the tilling depth applicable for any machine aggregates with disk working bodies, and its results can serve the agricultural machinery designers.

In-plane vibration of a rigid body attached to a flexible rotating beam

The dynamics of rotating systems are conventionally analyzed using models that assume the axis of rotation to be stationary. However, in instances such as helicopters and gas turbines with contra-rotating rotors such models which neglect the complexity arising from the coupling between the stator and the rotor due to their comparable masses can lead to inaccurate predictions. This paper examines the coupled stator-rotor dynamics of a model comprising a rigid (but non-stationary) body which is excited with a flexible rotating beam. Equations of motion governing the model's dynamics are developed and are found to have time-periodic boundary conditions. For the axisymmetric case the system loses its time dependence; the natural frequencies and the mode shapes vary with rotation speed. Specific modes soften within certain speed regimes, while other modes stiffen. Instabilities such as divergence and flutter are observed, and the effects of parameters on the critical speeds are investigated. The non-axisymmetric case is parametrically excited at twice the rotation speed. Floquet theory is employed to develop stability charts; regimes of instability exhibit a definitive structure comprising simple and combination parametric resonances. Temporal responses are modulated, and they exhibit characteristic side-banded frequency spectra.

Low speed lateral-directional aerodynamic and static stability analysis of a hypersonic waverider

Hypersonic waveriders have the potential to significantly reduce travel times on long haul civilian transport routes. The design of hypersonic aircraft is heavily influenced by the aerodynamic efficiency at the cruise Mach number, resulting in less than ideal geometries for subsonic flight. Waverider aerodynamics and stability in the low speed regime is rarely investigated and not well understood, but is crucial for horizontal take-offs and landings. This paper presents a combination of numerical simulation results and experimental data for the low speed propelled variant of the Mach 8 HEXAFLY-INT waverider. Aerodynamic, control and stability testing for lateral-directional cases was conducted in the University of Sydney 4 foot by 3 foot low speed facility. Computational fluid dynamics simulations are compared with wind tunnel tests for angles of attack between -5 and 15 degrees and angles of sideslip between -8 and 8 degrees. Throughout these ranges, aileron and rudder deflections up to 10 degrees are investigated. Results show that the vehicle aerodynamics are dominated by asymmetric wing and fin vortices, resulting in non-linear aerodynamic forces. At a centre of gravity location of 44.4% of the vehicle length the aircraft is stable directionally, but has lateral instability at angles of attack below -2 degrees. This is attributed to the low mounted wings with anhedral. The instability is minor and is not expected to result in an uncontrollable condition. Lowering the centre of gravity by approximately 2 centimetres, or 17% of the local fuselage height, can correct the instability. Lateral-directional dynamic stability was predicted using static derivatives and was found to be stable through the entire AoA range tested, with no dependence on mass moments of inertia. Both aileron and rudder controls are found to provide sufficient control authority, but the aircraft may benefit from increased rudder size. The results from this study, along with previous work on longitudinal stability and performance show the feasibility of moving to the flight test program, but aircraft dynamic stability must first be investigated.

The effect of wind direction shear on turbine performance in a wind farm in central Iowa

Abstract. Numerous studies have shown that atmospheric conditions affect wind turbine performance; however, some findings have exposed conflicting results for different locations and diverse analysis methodologies. In this study, we explore how the change in wind direction with height (direction wind shear), a site-differing factor between conflicting studies, and speed shear affect wind turbine performance. We utilized lidar and turbine data collected from the 2013 Crop Wind Energy eXperiment (CWEX) project between June and September in a wind farm in north-central Iowa. Wind direction and speed shear were found to follow a diurnal cycle; however, they evolved differently with increasing wind speeds. Using a combination of speed and direction shear values, we found large direction and small speed shear to result in underperformance. We further analyzed the effects of wind veering on turbine performance for specific values of speed shear and found detrimental conditions on the order of 10 % for wind speed regimes predominantly located in the middle of the power curve. Focusing on a time period of ramping electricity demand (06:00–09:00 LT – local time) exposed the fact that large direction shear occurred during this time and undermined turbine performance by more than 10 %. A predominance of clockwise direction shear (wind veering) cases compared to counterclockwise (wind backing) was also observed throughout the campaign. Moreover, large veering was found to have greater detrimental effects on turbine performance compared to small backing values. This study shows that changes in wind direction with height should be considered when analyzing turbine performance.

A conceptual method to assess ship-helicopter dynamic interface

The combined operation of a ship and a helicopter is ubiquitous in every naval organization. The operation of a ship in combination with the landing and take-off operations of a helicopter results in a very complex flow phenomenon. This is due to the presence of ship airwakes, strong velocity gradients and widely varying turbulence length scales. An accurate assessment of the resultant flow phenomena is an outstanding challenge for naval architects as well as researchers. A conceptual method to gain insight into the combined ship-helo flow phenomena over a helodeck is presented. The prime objective of this work is to develop an economical design tool employing both experimental as well as computational techniques to simulate the ship-helicopter coupled environment regime at early design stages reasonably well so as to ease the burden of expensive and risky sea trials. For this purpose, a simplified dynamic interface (SDI) model is proposed to investigate the coupled effects of ship airwake and helicopter rotor downwash. The paper reports a parametric analysis to study the coupled ship-helo airwake behaviour and its impact on helicopter fuselage over the ship helodeck for different ship speed regimes by the proposed SDI model. Further, an attempt has been made to set up preliminary design criteria to grade the ship-helicopter interface for ensuring minimum standards of safe helo operations. Finally, we discuss the impact of the coupled flow dynamics in terms of induced fuselage drag, cross-flow characteristics, rotor plane wake and velocity gradients existing over the helodeck region and evaluate the proposed design criteria.

Investigation of Post-Stall Aerodynamic Characteristics of Ventilated NASA LS (1)-0417 Airfoil

NASA LS (1)-0417 is an airfoil profile widely used in vehicle design especially in aircrafts for subsonic and transonic speed regimes. Performance of the airfoil is mainly determined by stall aerodynamic characteristics during flight. Further increase in stalling angle of the airfoil, the engineers adopts a single or multiple flaps in the trailing edge region of the main airfoil. The present study deals with a new attempt to achieve the post-stall or increased lift characteristics of NASA LS (1)-0417 airfoil beyond the stalling angle. The airfoil’s surface parts are subjected to allow the air to flow freely over and into the airfoil with increase in lift. The modified airfoil is designed from the base airfoil using the commercial design software and imported to the computational domain with boundaries around the model and meshed properly for solving the problem using the analysis software. The aerodynamic characteristics are compared with the baseline NASA LS (1)-0417 airfoil.

Simulation of agricultural landscape catenas based on the analysis of hydrodynamic characteristics of the underlying surfaces of slope lands

The agricultural landscape of slope lands is characterized by ecological instability and to ensure its equilibrium state a system of agronomic, melioration and environmental measures is carried out. Assessing the state of slope agricultural landscapes, it is necessary to take into account slope parameters, contour sizes, hydrological regime, types and varieties of soils, erosion processes, economic conditions, location, etc. Monitoring the above parameters will allow to detect hidden impacts or changes and restore the stability of the agricultural ecosystem early, for example, to maintain the hydrodynamic characteristics of the underlying surface for a certain period. Comprehensive research including methods of mathematical simulation and analysis carried out on the agricultural landscape catena is most effective. One of the fundamental scientific problems to be solved in this is to study and construct agricultural landscape catenas using the analysis of hydrodynamic characteristics of soil and vegetation cover of slope lands. It has been established that for compensatory melioration measures and engineering melioration systems planned on agricultural landscapes of slope lands, the following water flow rates occur: from 0.022 to 1.5 m/s for phytomelioration measures when slopes are rather steep; from 0.138 m/s for agricultural melioration measures at a slope of 0.08; and for traditional tillage rates exceed the critical ones and reach 0.8 m/s. According to the nomogram for determining the velocity diagram on a particular catchment slope, it is possible to assess and control anti-erosion melioration measures, revealing the actual speed regime of water flow in problem areas, and, therefore, it is possible to prevent erosion processes and preserve soil fertility on meliorated slope lands early.

Investigation of transport flow delay at unsignalized intersections with limited speed

Introduction. Many studies have argued that traffic delays at unregulated intersections depend on the intensity of the main flow and the intensity of pedestrian flow. Purpose. It is proposed to investigate traffic flow delays using the VISSIM software environment at unsignalized intersections at different flow rates. Results. Areas of the street and road network for experimental research were selected in the central part of Lviv. Triangles of visibility distance are calculated, problem places where it is necessary to establish a road sign 3.29 “Limitation of the maximum speed of movement” are defined. An analysis of existing methods for determining traffic delays at unregulated intersections is carried out at the paper. The method of estimating the average speed of traffic flow and the method of simulation modeling of transport flows in order to build a theoretical model are presented. The analysis of the dependence of the change of transport delays, obtained based on measured actual data and the method of modelling traffic flows, is carried out. The visibility distance for each intersection is calculated taking into account the speed mode. Graphical dependences of the change of the average and maximum length of the queue of vehicles under different modes of traffic light regulation in the secondary direction are given. It is determined that the average flow speed varies from 17 km/h to 38 km/h when changing the maximum speed limit from 15 km/h to 40 km/h. It is established that the lowest average traffic delay at unregulated intersections is observed at a traffic flow speed of 30 km/h. Conclusions. The substantiation of the introduction of the recommended speed regime on sections of streets with limited speed is given which takes into account transport delay, queue length, geometric parameters of the street, the presence of public transport stops and pedestrian crossings, traffic intensity and composition. The proposed method of controlling secondary traffic flows at unsignalized intersections, allows to increase traffic safety when traveling in secondary vehicles.

Wavelet-Based Adaptive Unsteady Reynolds-Averaged Navier–Stokes Simulations of Wall-Bounded Compressible Turbulent Flows

A wavelet-based adaptive approach, called wavelet-based adaptive unsteady Reynolds-averaged Navier–Stokes (WA-URANS), is proposed to solve the URANS equations for the computation of wall-bounded internal and external compressible turbulent flows. The new approach uses anisotropic wavelet-based mesh refinement, and its effectiveness is demonstrated for flow simulations with two different turbulence models, namely, the Spalart–Allmaras and models for a variety of two- and three-dimensional flow configurations with arbitrary geometries, different speed regimes, and various boundary conditions. Supersonic plane channel flow, a weakly compressible channel flow with periodic hill constrictions, a subsonic zero-pressure-gradient flat-plate boundary-layer flow, the separated flow over NASA wall-mounted hump, the Bachalo–Johnson flow (axisymmetric transonic bump flow), and a flow past a circular cylinder at a subcritical Reynolds number are tested as benchmark flows. The effectiveness and efficiency of the new wavelet-based approach are demonstrated by comparing the results of the WA-URANS simulations with literature data. This comprehensive validation of the WA-URANS approach encourages its application to practical problems of industrial interest, and demonstrates the feasibility of extending this approach to wavelet-based wall-modeled large-eddy simulation (LES) and hybrid URANS/LES. Finally, the current study serves as a baseline for the development of a unified hierarchical framework for eddy-resolving turbulence modeling, capable of performing computations of different fidelity, ranging from adaptive direct numerical simulations to adaptive URANS computations.

Effects of the Sea Surface Roughness and Sea Spray‐Induced Flux Parameterization on the Simulations of a Tropical Cyclone

AbstractA tropical cyclone (TC) interacts with the ocean through the interchange of surface fluxes of heat and momentum at the air‐sea interface. The sustainability and intensification of TCs are maintained by the enhancement in the latent heat flux in the high wind speed regime. An accurate calculation of heat fluxes is vital to understand the dynamics of the TC. The sea surface roughness is a crucial parameter that modulates the air‐sea fluxes. A coupled ocean‐atmosphere‐wave model is used to simulate TC Vardah over the Bay of Bengal during 10–15 December 2016. The study focuses on the influence of sea surface roughness on the heat fluxes, track, and intensity of TC Vardah. Four numerical experiments are performed with different parameterization schemes for surface roughness on the basis of (i) frictional velocity (Charnock), (ii) wave age, (iii) wave steepness, and (iv) a combination of wave steepness and wave age. A change in ocean surface roughness results in the modification of the cyclone track and heat fluxes. However, the effect of sea spray on the simulation of wind intensity of TC Vardah is only marginal. Out of the four experiments, the wave age‐based roughness parameterization was found to improve cyclone track, wind, and, hence, the generation of wind waves on the sea surface. In the case study of TC Vardah, the dynamic sea spray reduces surface wind speed up to 1.5 m/s which is within the uncertainty range of the model. An intercomparison of model experiments reveals the impact of surface heat fluxes on the TC Vardha characteristics.

Evaluation of the turbulence parametrization in the MOLOCH meteorological model

AbstractAn appropriate parametrization of turbulence is fundamental both in meteorological and atmospheric dispersion models, in order to properly simulate the dynamics of the flow and of the pollutants transported by it. The turbulence closure adopted in the meteorological model MOLOCH is presented, and its reliability and effectiveness are evaluated based on turbulent kinetic energy data measured at two suburban sites in north and south Italy. Very different topographical situations characterise the two sites, an Alpine and a coastal region, respectively. Particular attention is paid in assessing the low‐wind speed regime, a critical condition for air pollution, associated with turbulent features not yet fully understood. The analysis has proved that the turbulence closure in the MOLOCH model is able to capture and effectively reproduce the observed low‐level atmospheric turbulence processes, in all stability conditions.

Development of observation-based parameterizations of standard deviations of wind velocity fluctuations over an Indian region

The present study utilizes the turbulence observations over an Indian region, Ranchi, to study the diurnal and seasonal characteristics of mean and turbulent parameters in the atmospheric surface layer under different wind speed and stability regimes. Data for the year 2009 are chosen to compute mean and turbulent statistics using the eddy correlation technique and are studied within the framework of Monin–Obukhov similarity theory. The analysis of the observational behaviour of the standard deviation of wind velocity fluctuations (σi, i = u, v, w) normalized by friction velocity (u*) suggests that these parameters remain independent of stability of layer in near-neutral to moderately stable/unstable conditions. However, they are observed to increase following the classical 1/3 power law with increasing stability/instability in moderate to strong stable/unstable conditions. Further, an attempt has been made to develop possible parameterizations of these coefficients in terms of Monin–Obukhov stability parameter in low and moderate to strong wind regimes for four different seasons. The proposed observation-based functional forms the σi as functions of the stability exhibit different behaviours depending on the optimal values of unknown coefficients obtained for different seasons. However, within the limit of the uncertainty in the observed input parameters, the values of the season-dependent set of coefficients do not affect the overall statistical agreement between predicted and observed values of the normalized standard deviation of wind velocity fluctuations.

Complementarity modeling of monthly streamflow and wind speed regimes based on a copula-entropy approach: A Brazilian case study

Wind power energy has been showing significant growth in installed capacity around the world. This opportunity presents big challenges to operate power systems with high wind power penetration levels, considering the variability and intermittent behavior of this type of power source. To reduce uncertainties associated with this kind of power systems, researchers have explored the integration of wind power energy with other renewable energy sources, like solar and hydropower. For instance, the integration of wind and hydro systems can deal with the spatial and temporal complementarity of hydrological and wind regimes to produce energy. Therefore, it is necessary to consider the stochastic behavior and the dependence structures between these variables to define better operational policies. This study explores the spatial correlation of hydrological and wind regimes in different regions of Brazil and defines an entropy-copula-based model for the joint simulation of monthly streamflow and wind speed time series to evaluate the potential integration of hydro and wind energy sources. The proposed model showed a good adherence to the periodic behavior for both variables, and the results indicate that simulated scenarios preserved statistical features of historical data.

Low speed longitudinal aerodynamic, static stability and performance analysis of a hypersonic waverider

Hypersonic waveriders have the potential to significantly reduce travel times on long haul civilian transport routes. The design of hypersonic aircraft is heavily influenced by the aerodynamic efficiency at the cruise Mach number, resulting in less than ideal geometries for subsonic flight. Waverider aerodynamics and stability in the low speed regime is rarely investigated and not well understood, but is crucial for horizontal take-offs and landings. This paper presents a combination of numerical simulation results and experimental data for the low speed variant of the Mach 8 HEXAFLY-INT waverider. Aerodynamic, control and stability testing was conducted in the University of Sydney 4 foot by 3 foot low speed facility, while propulsion testing of the vehicle-integrated electric ducted fan was completed in the 7 foot by 5 foot tunnel. Motor thrust settings were tested for 8 lithium polymer cells connected serially drawing between 5 and 25 amperes. Computational fluid dynamics simulations are compared with wind tunnel tests for angles of attack between −5 and 25 degrees and elevon deflections between −10 and 10 degrees. Results show the aerodynamics is dominated by leading edge flow separation and vortex lift. At a centre of gravity location of 44.4% of the vehicle length, stability is observed up to 22 degrees angle of attack. Past this point, instability occurs due to vortex breakdown. The centre of gravity aft stability limit was found at 53.1% of the vehicle length. Overall, good agreement is seen between simulation and tunnel data, validating the modelling methods used. The low speed demonstrator can achieve trimmed flight from 12 m/s, but is only speed stable above 19 m/s. A cruise speed of 19 m/s is selected and can be attained with approximately −9.2 degrees of elevon and 7.1 degrees AoA for a centre of gravity location of 44.4%. Shifting the centre of gravity aft can reduce the trim angle of attack to below 6 degrees with −4 degrees elevon deflection. Take-off and landing can be achieved at 15 m/s between 9.8 and 12 degrees angle of attack, depending on centre of gravity configuration. A maximum climb rate of 2.1 m/s is predicted at 16.3 m/s based on the power settings tested. Overall, the results show the aircraft satisfies stability and performance requirements in the longitudinal axis.

Seasonal and regional variations of sinking in the subpolar North Atlantic from a high-resolution ocean model

Abstract. Previous studies have indicated that most of the net sinking associated with the downward branch of the Atlantic Meridional Overturning Circulation (AMOC) must occur near the subpolar North Atlantic boundaries. In this work we have used monthly mean fields of a high-resolution ocean model (0.1∘ at the Equator) to quantify this sinking. To this end we have calculated the Eulerian net vertical transport (W∑) from the modeled vertical velocities, its seasonal variability, and its spatial distribution under repeated climatological atmospheric forcing conditions. Based on this simulation, we find that for the whole subpolar North Atlantic W∑ peaks at about −14 Sv at a depth of 1139 m, matching both the mean depth and the magnitude of the meridional transport of the AMOC at 45∘ N. It displays a seasonal variability of around 10 Sv. Three sinking regimes are identified according to the characteristics of the accumulated W∑ with respect to the distance to the shelf: one within the first 90 km and onto the bathymetric slope at around the peak of the boundary current speed (regime I), the second between 90 and 250 km covering the remainder of the shelf where mesoscale eddies exchange properties (momentum, heat, mass) between the interior and the boundary (regime II), and the third at larger distances from the shelf where W∑ is mostly driven by the ocean's interior eddies (regime III). Regimes I and II accumulate ∼90 % of the total sinking and display smaller seasonal changes and spatial variability than regime III. We find that such a distinction in regimes is also useful to describe the characteristics of W∑ in marginal seas located far from the overflow areas, although the regime boundaries can shift a few tens of kilometers inshore or offshore depending on the bathymetric slope and shelf width of each marginal sea. The largest contributions to the sinking come from the Labrador Sea, the Newfoundland region, and the overflow regions. The magnitude, seasonal variability, and depth at which W∑ peaks vary for each region, thus revealing a complex picture of sinking in the subpolar North Atlantic.

Experimental research on Diesel Particle Filter (DPF) in relation to the fuel type

The experimental research is developed to validate or to dismiss theoretical suppositions considering the efficiency of particulate matter filters for internal combustion engines. This paper is pointing out the ideas of a practical test regarding soot impact upon the diesel particle filter from after treatment system, supplied with different fuels in operation mode. Measurements are recorded with after treatment system scanner and subsequently the experimental data are processed and graphically presented using digital module. Experience and know-how concerning the after-treatment system applied to the exhaust pipe of a Diesel engine is extremely useful in modelling the protocol for sustainable technical design of the automotive powertrains. The present paper outlines an applied process of controlling and analysing at least four parameters defining the clogging level of an actual diesel particle filter in K9K792 euro 5 internal combustion engine in relation to the fuel type. Engine supplied with Diesel standard has a wide range of clogging, but when changing to more blended fuels containing biodiesel from soy methyl ester and ethanol, the after treatment process is influenced significantly. The experimental testing is designed to reiterate for each fuel type in real time and after a distance of one thousand kilometres – in engine speed regime of two thousand revolutions per minute.

Universal relation between crack-growth dynamics and viscoelasticity in glass-rubber transition for filled elastomers

The characteristic power-law relationship between crack-growth speed (v) and tearing energy (Γ), Γ ~ vα in high speed regime (typically, v/cs > 10−3 where cs is the shear wave speed), is investigated for the filled elastomers with varying systematically the material parameters. The types of rubber, the concentration of filler and cross-linker concentration are widely varied in order to change the viscoelastic spectra of the elastomers. The power-law relationship is correlated with linear viscoelastic spectra, since Γ and the relaxation modulus are similarly dependent on temperature. An universal relation is found between the exponents α and κ of the relaxation modulus G(t) ~ t−κ in the glass-rubber transition regime, independently of the material parameters. The expectations of the existing theories fail to account for the observed relation, in particular for the elastomers with high filler contents or low cross-linker concentrations. The universal α-κ relation found here will contribute to predict the crack speed in high speed regime from the linear viscoelastic spectra of the elastomers, and will give a definite basis for the theoretical development in the crack-growth dynamics of elastomers.

The spectral amplitude modulation: A nonlinear filtering process for diagnosis of rolling element bearings

Rolling element bearings are the critical parts of every rotating machinery and their failure is one of the main reason of the machine downtime and even breakdown. For this reason, various methods have been proposed in the past for their early diagnosis. Among them, envelope analysis and cyclic spectral analysis (CSA) are the most effective and widely used approaches, working according to the principle of linear filtering process of signals to remove undesirable components. However, in many cases machine structures are excited in different frequency ranges by impacts generated when defects are engaged, hence, the signal should be filtered for multiple frequency bands to completely extract the defect signals. Also, finding the proper frequency bands for demodulation is not always a simple task. To overcome these challenges, in this paper an empirical and automated nonlinear filtering process will be proposed in which different components of a signal are decomposed based on their powers. Then, their squared envelope spectra are computed to seek the presence of bearings characteristic frequencies. Therefore, this method can be seen as complementary to the narrowband amplitude demodulation techniques. The phase of each filtered component is similar to the phase of the original signal but the magnitude is transformed. The idea is that reconstruction of a signal only by its phase preserves many useful features. A similar approach is employed by cepstrum pre-whitening for bearings diagnosis to reduce the effect of powerful exogenous sources which mask the bearings signals and, despite its simplicity, has achieved noteworthy outcomes. Finally, the performance of the proposed method is validated on real case data recorded from two test rigs. Also, its effectiveness is investigated under constant and variable speed regimes and in presence of various level of Gaussian and non-Gaussian (highly impulsive) background noise.

Wind speed regime in Tangier in 2021-2050

Introduction. The Moroccan energy system is highly dependent on external energy markets. This is why the current Moroccan energy strategy is focused on deployment of renewable technologies projects. Morocco has abundant wind resources.
 The purpose of this publication is identifying the characteristics of wind regime in Tangier in 2021-2050 to assess the wind potential.
 Results. This particular study used the data of regional climate modelling (RCM) with high spatial resolution of the CORDEX project. The article contains the results of RCM modelling using the RCP 4.5 scenario presented in the rectangular coordinate system with spatial resolution of ≈ 44 km. An ensemble of 11 climatic models was used for the analysis. To verify the RCM retrospective simulations for the period of 2011-2016 were used and to verify the RCM forecasts associated with wind speed we used the observations made at the Tangier meteorological station. The performed analysis allows us to conclude that average ensemble-based series of average monthly values are close to average values of the observed meteorological parameters. The models reflect the climatic parameters with varying degrees of accuracy and their results can be used to analyze future conditions of the climatic system in this region. Average wind speed for the period of 2021-2050 at the Tangier station will be equal to 5.1 m/s which exceeds the current value of 0.6 m/s. According to the forecast the wind speed in the territory of Tanger – Tetouan − Al Hoceima region will exceed 4.5 m/s. Comparison of the RCM-calculated wind speed value with the observational data for the period of 2005-2014 showed its increase. Based on the average annual wind speed values in each of the grid's nodes the linear regression coefficients were calculated.
 Conclusion. RCM-modelling showed that in 2021-2050 the territory of Tanger – Tetouan − Al Hoceima region will be dominated by the conditions being favourable for operation and further development of wind energy. Comparison of model calculations with observational data of the current climatic period showed that the Strait of Gibraltar area and the adjacent territories will see the wind speed increase in the future. The maximum value of wind speed annual run will be observed during the cold period of the year which coincides with the period of increased demand for electricity by its consumers.
 Directions of further research. The results of this study will be used as the basis for calculating the wind power in this region in 2021-2050.

Effects of finite water depth and lateral confinement on ships wakes and resistance

Wash waves produced by ships disintegrate river banks and coastal lines. This phenomenon of bank erosion is mainly due to the height of the waves. Various factors govern the formation of these waves and their amplitudes: the geometry of the water channel, the shape and the speed of the boat, etc.. These factors play an important role on the wave generation, in addition on the resistance of the ship and so on its fuel consumption. Whether to study the impact of wash waves on the ship's environment or its resistance, the analysis of the generated wake is essential. Hence a fine characterization of the wave field is necessary. This study proposes a comparison of wakes generated by two generic ships based on a Wigley hull with block coefficients 0.67 and 0.89 respectively representative of maritime and fluvial ships. The wakes generated in deep water and confined water configurations have been measured for different Froude numbers by a non-intrusive optical stereo-correlation method, giving access to a detailed and complete definition of the generated wave fields. The resistance of the ship hulls has been measured in deep and confined water configurations with a hydrodynamic balance. The results permit one to study the influence of both hull and water channel geometries on the ship wake, on the amplitude of the far-field generated waves and on the near-field hydrodynamic response. Moreover, resistance curves are obtained for both configurations and highlight the effect of both hull and water channel geometries on the resistance coefficient of the ship. A comparison of the resistance curves with or without the ship trim is conducted and shows the influence of the trim on the resistance coefficient in the different ship speed regimes.