Blade Rotational Speed Research Articles

Flow Field and Static Pressure Analysis of Adsorption Principle of Wall-Climbing Robot

The impeller is key element that brings about negative pressure adsorption. The efficiency of the impeller will determine the adsorption capacity of robot. In this paper, physical model is built based on the theory of fluid dynamics by taking a common high speed rotation of impeller as a research object. The basic parameters and boundary conditions are set and a 3D fluid dynamic simulation is done based on FloEFD. The factors such as blade curve, rotational speed and air inlet velocity which have effect on surface flow field impeller are investigated. Then the results are shown by figures and the study analysis is carried on.

Ship underwater noise assessment by the acoustic analogy. Part I: nonlinear analysis of a marine propeller in a uniform flow

The aim of this work is to analyze the hydroacoustic behavior of a marine propeller through the acoustic analogy and to test the versatility and effectiveness of this approach in dealing with the many (and relatively unexplored) issues concerning the underwater noise and its numerical prediction. In particular, a propeller in a noncavitating open water condition is examined here by coupling a Reynolds averaged Navier–Stokes hydrodynamic solver to a hydroacoustic code implementing different resolution forms of the Ffowcs Williams–Hawkings (FWH) equation. The numerical results suggest that unlike the analogous aeronautical problem, where the role played by the nonlinear quadrupole sources is known to be relevant just at high transonic or supersonic regime, the pressure field underwater seems to be significantly affected by the flow nonlinearities, while the contribution from the linear terms (the thickness and loading noise components) is dominant only in a spatially very limited region. Then, contrary to popular belief and regardless of the low blade rotational speed, a reliable hydroacoustic analysis of a marine propeller cannot put aside the contribution of the nonlinear noise sources represented by the turbulence and vorticity three-dimensional fields and requires the computation of the FWH quadrupole source terms.

PARAMETRIC STUDY OF PROPELLER TONE NOISE DUE TO NONUNIFORM FLOWS

This paper investigates the tone noise generation by submarine propellers operating in nonuniform flows. A frequency domain numerical approach is proposed. The flow nonuniformities due to submarine wakes are obtained from Computational Fluid Dynamics method. The results show that the velocity field and its harmonics depend greatly on the hull geometry and its appendages. The prediction of the radiated far-field tone noise due to a seven-bladed, highly-skewed propeller has been performed. A prediction of the acoustic pressure level for various blade skew angles shows that the tone noise reduction amount increases as the inflow velocity increases. The predicted dependence of the radiated noise on the inflow velocity, propeller diameter and blade rotational speed shows that the mean square sound pressure at the first-order blade passing frequency varies as the 3.3 power of the characteristic inflow velocity, the third power of the propeller diameter and with the second power of the blade rotational speed. Effects of blade number on the propeller tone noise directivity are also discussed, which shows that the characteristic coupling order between the main inflow harmonic and the rotating blades is the key to determine the directivity pattern.

식물공장을 위한 회전형 조명시스템 시제품의 광합성유효광양자속 분석

Rotational lighting system for plant factory is the way to decrease high installation cost of the existing lighting system. A few of LEDs are used at the rotational lighting system in comparison with the existing lighting system to supply artificial lights to crops. At rotational lighting system, the manufacturing cost becomes very low by comparing with the existing lighting system. In this paper, the photosynthetic photon flux (PPF) is investigated in order that plants may grow. And PPF is analyzed with the rotational speed of blade and LED output by using the rotational lighting system prototype and quantum sensor. It is confirmed that constant PPF value of is supplied with the blade rotation speed of 20rpm and LED output of IN 73%, CENTER 37% and OUT 50%. By comparing with the lighting system of existing plant factory, there is no difficulty to supply the light needed to grow plants by rotating a few of LEDs.

Spatial Filtering Effect of Tip Clearance Using Capacitance Displacement Sensor

According to structural characteristics and measurement needs of tip clearance of turbine engine and other rotating blade device, a leaves lattice model with vector characteristics is established. Based on measurement principle of the capacitive displacement sensor, the tip clearance measurement model is established. The spatial filtering effect and the impact of the tip clearance measurement results caused by blade thickness, sensing zone size, blade rotation speed and signal sampling rate is analyzed. The research results show that there is a minimum requirement about sensing zone size, blade rotation speed and signal sampling rate under the condition of certain blade thickness. The conclusion provides an important theoretical basis for the design of the tip clearance measurement system.

Analisis Kecepatan Maju Traktor dan Putaran Pisau Pemotong Pada Pengeprasan Tebu Ratoon

Analysis on Forward Speed of Tractor and The Spin of Cutter Knife on Ratoon Sugarcane Stubble ShaverABSTRACT. Cultivating ratoon sugarcane by using a stubble shaver conducted on sugarcane cultivation could save the cost of production. A good cultivation could be done by cutting the rest of the plant to the ground. The tool that commonly used was a hoe and a stubble shaver. Revitalization program that included the production of mechanical tools, in addition to providing lucrative benefits in the production business, on the other hand also had weaknesses in some aspects. To improve the quality and efficiency of the tool functions required the development and improvement tools. For example, the development and improvement efforts on tools sugarcane stubble shaver. Therefore, it still needed to conduct research on sugarcane stubble shaver machines to improve productivity especially in the cultivation of ratoon sugarcane stubble by improving the quality of results that would not break the ratoon sugarcane. The purpose of this study was to analyze the forward speed of the tractor and the blade rotation speed of ratoon sugarcane.

Investigation of the influence of processing parameters on physicochemical properties of puff pastry margarines using surface response methodology

The influence of some processing parameters on the physicochemical properties of two types of puff pastry margarines (PPM) manufactured at pilot scale was investigated. A Plackett–Burman experimentation design was used to select the processing parameter combinations to test. A pilot-scale line, equipped with a scraped surface heat exchanger (SSHE) and a resting tube, was used to produce the margarines. The considered processing parameters were the “buffer tank” temperature, the flow rate, the SSHE temperature, the scraper blade rotational speed and the resting tube temperature (two levels by parameter). The margarines were stored at 15 °C and 20 °C. The physicochemical properties investigated were the solid fat content (SFC), the dropping point (DP), and the texture (hardness) at these two temperatures. The results were statistically analyzed by the response-surface methodology to find out the processing parameters influence on each physicochemical property. Experimental results confirmed that physical properties of both margarines were strongly influenced by the processing parameters. In this study, whatever the formulation or the physicochemical property analyzed, it was shown that the SSHE temperature, the flow rate and the resting tube temperature were the most frequently significant parameters.

Power consumption profile analysis during wet agglomeration process: Energy approach of wheat powder agglomeration

Abstract Mechanical energy input during mixing is one of the key stages of the mixer agglomeration process. It allows the distribution of water over the powder, the formation and growth of agglomerates, and homogenization of the agglomerate properties. The objective of the present work is to determine the power consumed by the wet agglomeration process of a reactive granular material, in the specific case of agglomeration of durum wheat semolina under the conditions of couscous grain production. Our study attempts to investigate the effects of process conditions (i.e. blade rotation speed, mass load, and water addition level) on the distribution of the different energy costs consumed by the mixer during the wet agglomeration process. As a baseline, we first measured the energy consumption by the motor for no-load mixing. To evaluate the energy consumption to transport inert load, we measured the energy consumption by the motor after introduction of different masses of durum wheat semolina without adding water. Finally, we study the energy consumption of the agglomeration process during mixing after water addition. Results demonstrate that the energy specifically consumed for agglomeration process increases with water content, from 9% (at 22% water content) to 26.6% (at 42% water content). However, the energy necessary to form and structure the agglomerates only represent at the maximum one third of the total energy consumed by the equipment.

Wind Turbine Performance in Controlled Conditions: Experimental Results

Abstract Experimental research has been completed using a custom designed and built 4.3 m diameter wind turbine in a large scale university operated indoor wind facility. The primary purpose of the turbine testing outlined here was to determine the power production of the turbine. These tests were completed over a wide range of wind speeds and turbine blade rotational speeds. Two other previous large scale wind turbine tests are also briefly discussed with a comparison outlining the unique aspects of these experiments. Power production tests were completed covering a range of mean wind speeds, 6.4 m/s to 11.1 m/s nominal, and turbine low speed shaft rotational rates, 40 rpm to 220 rpm. This testing allowed the total power produced by the blades to be determined as a function of input wind speed, as traditionally found in power curves for commercial turbines. The coefficient of power, CP , was determined as a function of the tip speed ratio λ which gives insight into the peak power production of the experi...

식물공장을 위한 인공광 회전형 스마트 조명 제어시스템 개발

Rotational smart lighting control system provides artificial light to plants on planting board by rotational lighting system. As the lighting system of existing plant factory has high cost problem due to the installation for many lighting equipments, the lighting system was developed to rotate less number of lighting equipments to reduce cost. In this paper, the illuminance, luminous flux and photosynthetic photon flux density(PPFD) that plants need to grow were calculated. And the light intensity at each measured location considering the rotational speed of blade were analyzed by the simulation and the experiment.

Experimental Study on Performance of Vertical Axis Wind Turbine with NACA 4-Digital Series of Blades

The experimental studies of output power performances of a vertical-axis-wind-turbine (VAWT) had been conducted in suction-type low speed wind tunnel with various free stream velocity. Torque and rotation speed of blades were measured by using torque meter and optical detector to analyze the effect of blade-section shape on the performance of wind turbine. The test model of experiments in the research was H-rotor VAWT. Three shapes of the NACA 4-digital series blade-section, NACA0022, NACA6404, and NACA6422 were taken in this work. Effects of thickness and camber of blade-section, blade numbers, and blade setting angles on the performance of VAWT have been analyzed in detail. The results show that NACA6422 blade-section has rotation speed of 42% higher than that of NACA0022 when the free stream velocity is below 12 m/s and the blade numbers are 4-blade type. Wind turbines with NACA6422 blades also showed that about 10% higher output power than that of NACA0022 blades among the tested range of free stream velocity. Results indicated that wind turbine with blades of anti-symmetric and thick blade-section was generally more suitable for applying to VAWT. All results of this study can be used the optimization design of VAWT blades in further.

Experimental Study on Chaotic Mixing Created by a New Type of Mixer with Rotational Blades

The aim of this paper is an experimental investigation of laminar mixing in a new type of chaotic mixer, which has been proposed by Hwu (2008), by means of material line deformation. The mixer is a circular cavity with two rotational blades which move along a semicircular path and drive the fluid motion. The flow visualization is carried out by marking of the free surface of the flow with a tracer in working fluid. In the present study the effects of length and rotational speed of blades on mixing efficiency are evaluated by measuring of the area covered by the tracer. As a result, it is demonstrated that the goodness of mixing increases as rotational speed of blades increases. Also, it is detected that the mixing efficiency strongly depends on the lengths of rotating blades.

Computational fluid dynamics simulation of the aerodynamics of a high solidity, small‐scale vertical axis wind turbine

ABSTRACTA computational fluid dynamics simulation was performed for a small‐scale, high solidity (σ = 0.48) H‐type Darrieus vertical axis wind turbine. Two‐dimensional unsteady Reynolds‐averaged Navier–Stokes equations were solved for the turbine numerical model, which has a large stationary domain and smaller rotating subdomain connected by a sliding mesh interface. The simulation results were first validated against steady‐state airfoil data. The model was then used to solve for three rotating blades with constant ambient flow velocity (Re = 360,000) over numerous blade speed ratios. The high solidity and the associated low blade speed ratio and rotational speed of the turbine result in complex flow–blade interaction mechanisms. These include dynamic stall resulting in vortex shedding, vortex impingement on the source blade and significant flow momentum extraction causing reduced power production from the downstream blade pass. Copyright © 2011 John Wiley & Sons, Ltd.

A Method for Evaluating the Aerodynamic Stability of Multistage Axial-Flow Compressors

Abstract A new simple engineering parameter to evaluate the stability of multistage axial compressors has been derived. It is based on the stability analysis for a small circumferential disturbance imposed on the steady-state flow field. The analytical model assumes that the flow field is two dimensional and incompressible in the ducts between blade rows although the steady-state density is permitted to change across the blade rows. The resulting stall parameter contains terms that relate to the slope of the pressure rise characteristic of the blade rows and the inertia effects of the fluid in the blade rows and ducts. The parameter leads to the classical stability criteria based on the slope of the overall total to static pressure rise coefficient in the limit where constant density and constant blade rotational speed are assumed across the compressor. The proposed stall parameter has been calculated for three different multistage axial flow compressors, and the results indicate that the parameter has a strong correlation with the measured stability of the compressors. The good correlation with the test data demonstrates that the newly derived stall parameter captures much of the fundamental physics of instability inception in multistage compressors, and that it can be a good guideline for designers and engineers needing to evaluate the stability boundary of multistage machines.

Real-time diagnosis of melting and mixing processes in internal mixer by ultrasound

An ultrasonic technology on melting and mixing processes in the internal mixer real-time, non-intrusively and non-destructively is investigated. Ultrasonic signatures, such as amplitude of transmission and reflection echoes, as well as visual observation, and mechanical torque measurement, were used for the diagnosis of the melting process of low-density polyethylene (LDPE) and the mixing processes of the melted LDPE with a calcium carbonate (CaCO 3) powder. Phase change from solid to liquid, partially melted pellets, and distributing progress of CaCO 3 powder during the melting and mixing processes were successfully monitored by ultrasound. Melting and mixing completions were determined when ultrasonic reflection echo reached its upper stable level. Larger amount of CaCO 3 powder required longer mixing period. Higher temperature of mixing chamber and faster rotation speed of blades reduced mixing period. The presented ultrasonic technique can be utilized to optimize the melting and mixing processes.

Melting Quality of Polymers in Internal Mixer Diagnosed by Ultrasound

Abstract Real-time, non-intrusive and non-destructive ultrasonic technology has been used to monitor the melting process in an internal mixer. Visual observation, mechanical torque measurement, and ultrasonic signatures, such as amplitude and time delay of transmission and reflection echoes were used for the diagnosis of the melting process of low density polyethylene (LDPE). Phenomena during the melting process, including phase change from solid to melt, partially melted pellets, air bubbles inside the melt, were successfully monitored by ultrasound. The ultrasonic signatures were able to determine when the polymer has melted completely. The method of moving standard deviation (MSD) was applied to establish the melting completion timing accurately. Higher temperature of mixing chamber and faster rotation speed of blades reduced melting completion period, indicated by MSD of ultrasonic signatures. The presented ultrasonic technique can be utilized to optimize the melting process.

헬리콥터 복합재 블레이드 충돌하중 연구

본 연구의 목적은 주로터 블레이드와 장애물 충돌 시 실제 파괴형상과 유사한 시뮬레이션을 통해 발생되는 하중을 구하고, 이것을 이용하여 허브 및 변속장치의 안전성을 검토함으로써 승무원의 안전성을 확보하는 것이다. 헬리콥터의 실제 운용 시에 주로터 복합재 블레이드 바깥쪽 10% 지점에 직경 203mm의 강체실린더가 충돌할 경우에도 주로터주축은 파괴가 발생하지 않아야 하고 변속장치가 탑승공간으로 침투하는 위험한 변위가 발생하지 않아야 한다. 강체와 블레이드 충돌 시 주로터의 주축과 변속장치의 영향성을 확인하기 위하여 탄소성 손상 재질을 사용하여 복합재 블레이드와 나무(강체실린더의 경우는 강체)의 해석모델을 구성하였으며, 파괴진행과정을 실제와 유사하게 구현하기 위해 여러 개의 접촉면을 생성하여 충돌해석을 수행하였고, 구형베어링 및 리드래그댐퍼에 전달되는 하중을 구하였다. 또한, 블레이드 회전속도 및 피치각도의 변화가 전달하중에 미치는 영향을 검토하였다. The objective of this study is ensuring safety of cabin when the blade impacts into a obstacle by verifying safety of the rotor mast and the transmission using impact loads calculated from the simulation. The rotor mast shall not fail and the transmission shall not be displaced into occupiable space when the main rotor composite blade impact into a 8 inch rigid cylinder in diameter on the outer 10% of the blade at operational rotor speed. To calculate the reaction loads at the spherical bearing and lead-lag damper, blade impact analysis was performed with FE model consist of composite blade, tree(or rigid cylinder) using elastic-plastic with damage material and several contact surfaces which were created to describe a progress of actual failure. Also, the reaction loads were investigated in change of blade rotation speed and pitch angle.

Behavioral Responses of Bats to Operating Wind Turbines

Abstract Wind power is one of the fastest growing sectors of the energy industry. Recent studies have reported large numbers of migratory tree‐roosting bats being killed at utility‐scale wind power facilities, especially in the eastern United States. We used thermal infrared (TIR) cameras to assess the flight behavior of bats at wind turbines because this technology makes it possible to observe the nocturnal behavior of bats and birds independently of supplemental light sources. We conducted this study at the Mountaineer Wind Energy Center in Tucker County, West Virginia, USA, where hundreds of migratory tree bats have been found injured or dead beneath wind turbines. We recorded nightly 9‐hour sessions of TIR video of operating turbines from which we assessed altitude, direction, and types of flight maneuvers of bats, birds, and insects. We observed bats actively foraging near operating turbines, rather than simply passing through turbine sites. Our results indicate that bats 1) approached both rotating and nonrotating blades, 2) followed or were trapped in blade‐tip vortices, 3) investigated the various parts of the turbine with repeated fly‐bys, and 4) were struck directly by rotating blades. Blade rotational speed was a significant negative predictor of collisions with turbine blades, suggesting that bats may be at higher risk of fatality on nights with low wind speeds.

Effect of mixing conditions on the rheological and optical properties of chemically modified poly(ethylene terephthalate‐co‐ethylene isophthalate)

AbstractThe optical properties and rheological properties were studied for binary reactive blends composed of poly(ethylene terephthalate‐co‐ethylene isophthalate) [P(ET–EI)] and a styrene–acrylate based copolymer with glycidyl functionality. The blade rotation speed in the internal mixer greatly affected the structure and properties for the blend system. Intensive mixing at a high rotation speed enhanced the optical transparency because of the reduced particle size of the dispersed phase. The graft copolymer generated by the reaction between P(ET–EI) and the modifier was responsible for the fine morphology. Furthermore, the copolymer also enhanced the elastic nature in the molten state because it acted as a long‐chain branched polymer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008

Aspects of the Dynamic Response of a Small Wind Turbine Blade in Highly Turbulent Flow: Part 2 Predicted Blade Response

The work described in this paper compares the measured blade root flapwise bending moment on a 400W 3-bladed wind turbine to analytical predictions and calculations from the “simple load model” of the International Electrotechnical Commission safety standard for small wind turbines. The predictions use the method of Eggleston and Stoddard (1987) and were found to over predict the measured azimuthal averaged flapwise root bending moment. During an extreme yaw event, the instantaneous blade root flapwise bending moment was found to be dominated by the gyroscopic moment from the blades. The calculated fatigue loads from the safety standard were some 25% lower than the measured values, with the calculated yaw moment under-predicting the measured flapwise bending moment for a range of turbine yaw rates with the error increasing with increasing blade rotational speed. A Combination of the calculated root bending moment from yaw and yaw error was found to over-estimate the root flapwise bending moment especially at high rotational speeds.