Simulating NACA Equations Used in Optimizing Wind Turbine Blade Design: محاكاة معادلات NACA واستخدامها لتحسين تصميم شفرة العنفة الريحية

Aerodynamic scientists are interested in geometry definition and possible geometric shapes that would be useful in design. This paper illustrates a simulation of a NACA four digits airfoil blade profile using MATLAB. As airfoil design became more sophisticated, this basic approach has been modified to include additional variables, and suggestions for the chord line length at the root and at the end of the blade. as well as changes in the twisting angle of the blade and its thickness, this helps to reduce the weight of the blade significantly Simulating NACA equations is very useful in obtaining coordinates of airfoil curvature for the whole series of NACA four digits, which is very effective in optimizing blade design. In order to get an optimal operating performance and high efficiency for the airfoil, the blade surface must be smooth and does not suffer any discontinuities or undefined cases, which cause separation of the boundary layer during the airflow, and get as a result great energy losses. Therefore, the conditions for the continuity of the blade was extracted using mathematical analysis, so the air flow does not suffer any interruptions which reduce the efficiency. This enable us to determine the locations of the maximum thickness of the blade sections on the chord along the blade, in addition to specifying conditions for the chord line length at the root and at the end of the blade which keep the blade curvature continuous and doesn’t have any irregular points, which also facilities writing the necessary programs.

Dynamic responses of elastic marine propellers in non-uniform flows

This paper focuses on the development of a three-dimensional panel method in time and frequency domains combined with the finite element method for analyzing the hydroelastic responses of rotating marine propellers in the wake of ships. A fully non-penetration boundary condition imposed on the deformed blade surface is conducted, in which the corrections of both the incoming flow velocities and the normal vectors imposed on the deformed and undeformed blade surface are taken into account. The added-mass and -damping matrices due to strongly coupled fluid-structure interaction are considered. Results of the present method are compared with experimental data available in the literature. It is observed that the fully non-penetration boundary condition applied on the deformed blade surface should be imposed to predict the unsteady performance of elastic propellers, which is due to the change of the added damping predicted by considering different non-penetration boundary conditions.

Вплив технології виготовлення випаровуємих катодів на якість іонно-плазмових покриттів лопаток турбін

The article considers coatings deposited on turbine blades via plasma vapor deposition (PVD) method with Ni-Cr-Al-Y cathodes obtained using powder metallurgy (PM) and electron beam remelting process (EBMR). The study analyzes the effect of cathodes manufacturing techniques on surface roughness of rotor turbine blades. Task: to examine a microstructure and chemical composition of the considered cathodes; to quantify a droplet phase of a heat-resistant coating of turbine blades subdivided into size-fractions. Methods used optical microscopy, SEM-analysis. Next results were obtained. In the microstructure of two cathodes under study, it is revealed γ-solid solution with intermetallic Ni-Cr-Al and yttrium-based phases. Simultaneously, distribution of the yttrium phase in the PM-cathode more uniform in compare with EBMR-cathode. Metallographic studies showed that yttrium phase in the structure of the PM-cathode is highly-dispersed, with sizes up to 5 microns, and due to structural and dimensional heredity received during cathode hot isostatic pressing compaction. The structure of the cathode obtained using EBMR-process is a series of the conglomerates of intermetallic phases, with more than 50 microns long, which are branched out on volume. The compliance of the chemical composition of the cathodes under study to requirements of the specifications is established. After the coating deposition on turbine blades by a PVD-method with cathodes under study, were not observed any coating delamination, and their thickness corresponded to the specifications. With a distribution analysis of droplet phase on the turbine blade surface were established that coatings with PM-cathode have been characterized by complete absence of a 65 microns droplet phase, and has half less 25…45 microns droplet phase compared with the EBMR-cathode. Conclusions. The coating with PM-cathode has smaller droplet phase on the turbine blade surface and as a result improved their roughness and gas path surface state. The use of PM in the production of the cathodes for protective coatings provides stable performance of installation and provides long-term operation time of cathodes, compared with the EBMR-cathodes.

Investigation on the Transient Characteristics of Self-Priming Pumps with Different Hub Radii

Self-priming pumps, important fluid equipment, are widely used in the disaster relief and emergency fields. Meanwhile, the impeller is the only rotational unit of the self-priming pump, which plays an essential part in the power capability of the pump. In this paper, impellers with different hub radii are proposed; by comparing the internal flow characteristics, blade surface load, pressure pulsation characteristics, and radial force distribution of each scheme, the relationship between transient characteristics and hub radius is obtained. The results present that the impeller with a large hub radius can not only weaken the pressure pulsation, blade surface load, and radial force distribution, but also improve the ability of the blade to work on the internal flow field. Finally, the relevant hydraulic experiment is conducted, with the difference between the experiment and calculation below 3%, which ensures the accuracy of the calculation results.

Blade Roughness Effects on Compressor and Engine Performance—A CFD and Thermodynamic Study

Degradation of compressors is a common concern for operators of gas turbine engines (GTEs). Surface roughness, due to erosion or fouling, is considered one of the major factors of the degradation phenomenon in compressors that can negatively affect the designed pressure rise, efficiency, and, therefore, the engine aero/thermodynamic performance. The understanding of the aerodynamic implications of varying the blade surface roughness plays a significant role in establishing the magnitude of performance degradation. The present work investigates the implications due to the degradation of the compressor caused by the operation in eroding environments on the gas turbine cycle performance linking, thereby, the compressor aerodynamics with a thermodynamic cycle. At the core of the present study is the numerical assessment of the effect of surface roughness on compressor performance employing the Computational Fluid Dynamics (CFD) tools. The research engine test case employed in the study comprised a fan, bypass, and two stages of the low pressure compressor (booster). Three operating conditions on the 100% speed-line, including the design point, were investigated. Five roughness cases, in addition to the smooth case, with equivalent sand-grain roughness (Ks) of 15, 30, 45, 60, and 150 µm were simulated. Turbomatch the Cranfield in-house gas turbine performance simulation software, was employed to model the degraded engine performance. The study showed that the increase in the uniform roughness is associated with sizable drops in efficiency, booster pressure ratio (PR), non-dimensional mass flow (NDMF), and overall engine pressure ratio (EPR) together with rises in turbine entry temperature (TET) and specific fuel consumption (SFC). The performance degradation evaluation employed variables such as isentropic efficiency (ηis), low pressure compressor (LPC) PR, NDMF, TET, SFC, andEPR. The variation in these quantities showed, for the maximum blade surface degradation case, drops of 7.68%, 2.62% and 3.53%, rises of 1.14% and 0.69%, and a drop of 0.86%, respectively.

Investigating of Flow Field and Power Performance on a Straight-blade Vertical Axis Wind Turbine with CFD Simulation

Forecasting the power performance and flow field of straight-blade vertical axis wind turbine (VAWT) and paying attention to the dynamic stall can enhance more adaptability to high turbulence and complicated wind conditions in cities environment. According to the blade element-momentum theory, the force of blade is analyzed in one period of revolution based on the structural characteristics of straight blade airfoil. The power performance of VAWT obtained by computational fluid dynamics (CFD) simulation is compared with experiment to estimate the accuracy about the numerical simulation results. As a result, the trend of average value of simulation Cpower is entirely consistent with the value of experiment data, and the extreme value of average Cpower of VAWT is 0.225 for tip speed ration (TSR) λ=2.19 when the freestream velocity is 8 m/s. The flow separation around the blade surface also gradually changes with the azimuth angle increasing, and the maximum pressure difference on the blade surface appears in the upstream. In the case of high leaf tip velocity, the synthetic velocity is much larger than the incoming wind velocity, and the angle of synthetic velocity increases slightly with the increase of blade tangential velocity. Thus, the angles of attack are very close in two TSRs λ=2.19 and 2.58. The research provides a computational model and theoretical basis for predicting wind turbine flow field to improve wind turbine power performance.