Set Of Blades Research Articles

Histological Structure of Stingrays (Gymnura poecilura) Heart

Stingrays belong to the sub class of Elesmobranchii or often termed as cartilaginous fish. The heart is one of the circulating organs in fish that serves to pump blood throughout the body. The fish circulatory system is a closed system with a single blood circulation. This study aims to determine the histological structure of stingrays' hearts. The fish used for this study are butterfly stingray (Gymnura poecilura) obtained from Depok Beach, Bantul. The equipments used in this research are a set of surgical instrument, bottles, paraffin board, razor blades, embedding cassettes, staining jar, microtomes, slide glass, cover glass, and binocular microscopes. Materials used are stingrays, chloroform, bouin, alcohol, xylol, aquades, paraffins, hematoxylin and eosin, albumin, and entelan. The staining used in this research is HE (Hematoxylin-Eosin) method. Based on the results of the research and observation, the heart of stingrays consists of epicardium, endocardium, myocardium, muscle cells, and cell nuclei. Epicardium is the outermost layer of the heart that is coated by the tissue as a protective. The inner endocardium is coated with epithelial cells. Myocardium are the middle layer of heart wall. The smooth muscle cells are the heart muscle. Cell nuclei are usually present in smooth muscle cells.

UH-1H와 UH-60 헬리콥터 블레이드의 제자리 비행 시공력 성능 및 소음 특성

Aerodynamic characteristics and noise fields of main rotors in hovering motion for UH-1H and UH-60 operated in Korean army were analyzed numerically. Unlike UH-1H blade, UH-60 blade has a 20˚ swept tip, which can decrease the wave drag at high speed range. A density-based compressible and incompressible solver of CFD++ was used for flow analysis. The Farassat formula 1A as a way of acoustic analogy was adopted for noise fields. Rotational speed of the blade set to maximum of design value, and any local shocks or delocalization of shocks from the blade were not observed at given rotational speed. FFT analysis was performed for timewise noise data, and overall sound pressure level (OASPL) was obtained based on the A-weighted scale. It turns out that the OASPL of UH-60 rotor at the designed tip speed shows 12 dB (18 dBA) lower than that of UH-1H one.

Development of a Multipurpose Power Weeder

Paddy is grown in almost all states of India and the state of Odisha contributes 4.0 million hectares to rice cultivationpractice. In India Rs. 4,200 million worth of crop is being lost every year due to weeds. There are many types of mechanicalweeders available for vegetable crops with wide working width. These are not suitable for line sown paddy field. There is no suchpower weeder available which can work in both wet land and dry land condition. To eradicate these problems one power weederwas developed. The power requirement of the weeder was first calculated and found to be 1.1 kW. Hence, the available petrolengine of 1.33 kW with speed reduction of 34:1 was taken for fabrication of the weeder. Initially, three types of blade (L-type, Ctype,hatchet type) were developed to see the efficacy of the blades. Each set of blade was fitted with the weeder and evaluated inline sown paddy in dry land as well as in transplanted paddy in wet land by attaching a suitable float and compared with theconventional weeding method. The highest weeding efficiency of hatched type blade was found to be 84.30% in wet land and82.280 % in dry land, whereas the same for L-type blade and C type blade weeders were 72.83% and 62.79% in wet land and71.03% and 63.67% in dry land at a soil moisture content of 14.5% respectively. The performance index of hatched shape, Lshape and C shape blade weeder were observed to be 186.49, 117.70 and 125.15 in wet land and 190.81, 148.16 and 126.47in dryland at 14.5% moisture content respectively. At the same moisture content i.e.14.5%, the highest plant damage of 11.60% wasobserved with L type blades while the lowest plant damage of 4.0% was observed with hatchet type blade. The increase in heartrate (∆HR) of 20.667 bpm was achieved for L type blade while the lowest of 18.667 bpm achieved in hatchet type blade at thesame speed. It is concluded that the developed weeder with hatched type blade is most suitable for weeding in both wetland aswell as dry land line sown paddy field. The cost of operation of the developed weeder was found to be Rs 177.10/h and Rs4997/ha

Utilizing a diagnostic kV imaging system for x-ray psoralen activated cancer therapy (X-PACT)

X-ray psoralen activated cancer therapy (X-PACT) is a new therapeutic approach that has been shown to induce tumor cell apoptosis and cytotoxicity in vitro, and slow tumor growth in BALB/c mice with syngeneic 4T1 tumors. X-PACT is accomplished by injection of co-incubated psoralen and phosphors; the phosphors emit UV to activate psoralen, and are activated by an external kV source. Here we describe application of a kV x-ray source mounted on board a medical linear accelerator for X-PACT in preparation for a phase I clinical trial of X-PACT for spontaneous tumors in pet dogs. We commissioned a 80 kVp beam at 50–80 cm from the source with varied blade settings to achieve rectangular collimated beams. Commissioning included dosimetry measurements, developing a formalism for absolute dose calculation in water, FLUKA Monte Carlo based planning and evaluation, and verification measurements. Dosimetry measurements included AAPM TG-61 absolute dose calibration, depth dose curves, backscatter and collimator scatter factors, heel effect, and leakage. Reasonable agreement was achieved between measurement and Monte Carlo, and between calculated dose and verification measurements. Finally, we demonstrate the X-PACT treatment process for an example dog with a 3–5 cc left hip sarcoma located at a 2 cm depth. The absolute dose formalism indicated 21 pulses of 160 mAs were required to deliver the prescription dose of 0.6 Gy to 2.8 cm depth. The dose distribution was calculated with the Monte Carlo planning tool and visualized at 1 × 1 × 2 mm3 spatial resolution. A dose enhancement in the hip bone of up to 4.5 Gy was observed. This work demonstrates that X-PACT is feasible utilizing diagnostic kV sources such as those mounted on a clinical linear accelerator, and reports commissioning and treatment planning data and formalism respectively.

Preliminary Design, Modeling, Production, and First Evaluation Tests of a Ti–Al Gas Turbine Blade

The aim of this work is to design a lightweight, creep-resistant blade for an axial single-stage micro-gas turbine. The selected process was casting of an intermetallic titanium/aluminum alloy. All the project phases are described, from the preliminary thermodynamic and geometric stage design, to its three-dimensional (3D) modeling and the subsequent finite element method–computational fluid dynamics (FEM-CFD) analysis, to the manufacturing process of the single rotor blade. The blade making (height 7 cm and chord 5 cm, approximately) consisted in a prototyping phase in which a fully 3D version was realized by means of fused deposition modeling and then in the actual production of a full-scale set of blades by investment casting in an induction furnace. The produced items showed acceptable characteristics in terms of shape and soundness. Metallographic investigations and preliminary mechanical tests were performed on the blade specimens. The geometry was then refined by a CFD study, and a slightly modified shape was obtained whose final testing under operative conditions is though left for a later study. This paper describes the spec-to-final product procedure and discusses some critical aspects of this manufacturing process, such as the considerable reactivity between the molten metal and the mold material, the resistance of the ceramic shell to the molten metal impact at high temperatures, and the maximal acceptable mold porosity for the specified surface finish. The CFD results that led to the modification of the original commercial shape are also discussed, and a preliminary performance assessment of the turbine stage is presented and discussed.

Effect of sizing of a Savonius type vertical axis micro wind turbine

The primary objective of this paper is to study the effect of sizing of a multi-bladed Savonius rotor on power output. Initially, a base model of the micro wind turbine with 8, 16 and 24 blades with rotor diameter of 300 mm and blade length of 160 mm with a diameter of 40 mm was designed and its power outputs were measured over a range of wind speeds using a wind tunnel. Then the outputs were compared with the modified design by doubling the diameter of the rotor and the length and radius of the blades. Additionally, the output power from the base model was compared with the power outputs of another modified design by keeping the rotor diameter and blade length constant (300 mm and 160 mm) but varying the blade diameters (20 mm, 40 mm and 80 mm) respectively. Results show that the average power increased by about 80% when comparing the base model and double size for all 3 sets of blades (8, 16, 24 blades). It is also found that the power increased about 50% when the diameter of the blade is scaled up by double the size.

Flume-scale testing of an adaptive pitch marine hydrokinetic turbine

Modern marine hydrokinetic turbine blades are typically constructed from fiber reinforced polymer (FRP) composites, which provide superior strength- and stiffness-to-weight ratios and improved fatigue and corrosion resistance compared to traditional metallic alloys. Furthermore, numerical studies have demonstrated the possibility of tailoring the anisotropic properties of FRP composites to create an adaptive pitch mechanism that can improve system performance, especially in off-design or varying flow conditions. Potential benefits of an adaptive pitch system include increased lifetime energy capture, reduced hydro-elastic instabilities, reduced risk of mechanical failure, and improved efficiency, load shedding, fatigue life, and structural integrity. In this work, static and dynamic testing results for a flume-scale marine hydrokinetic turbine system are presented. Two sets of adaptive composite blades are compared to neutral pitch composite and rigid aluminum designs. Static testing was used to quantify the mechanical load-deformation response of each blade type. Additionally, instantaneous blade and full system loading was measured during dynamic flume testing, allowing a multilevel analysis of adaptive blade performance. Experimental results show notable shifts in the power and thrust coefficients and significant load adjustments induced through passive pitch adaptation, suggesting that adaptive pitch composite blades could be a valuable addition to marine hydrokinetic turbine technology.

A detailed investigation of a novel vertical axis Darrieus wind rotor with two sets of blades

The lift-type vertical axis wind turbine (Darrieus rotor) is considered to be a promising device for harnessing wind energy due to its potential advantages. Traditionally, a standard Darrieus rotor has a single ring of airfoils (two or three airfoils) that spins about a vertical axis and has low starting torque. A few researchers have stated that the Darrieus rotor with two sets of blades is likely to improve not only the starting ability but also the power coefficient. However, they have not provided sufficient evidence to support their statement. Thus, in this paper, we conducted a detailed computational fluid dynamics (CFD) investigation on the characteristics (e.g., power output, static torque, vortex, and pressure contours) of this rotor with two sets of blades. The effect of the distance between the outer and inner blades on the performance of this rotor was also discussed and quantified. The findings of this paper are expected to help in developing this new type of Darrieus rotor and offer valuable suggestions for real field applications.

Experimental Investigations on the Performance Characteristics of a Modified Four Bladed Savonius Hydro-Kinetic Turbine

Torque variation along the angular positions of the rotor blade and lower efficiency are the main drawbacks of Savonius turbine. To overcome these problems several attempts have been made by the researchers in the recent past. In this work, an attempt has been made to increase the torque along the angular positions where the torque is low, by placing a set of additional blades called secondary blades in front of the concave side of main rotor blades. These secondary blades are interacting with the flowing fluid when the main blades are not in action. The performance of the modified Savonius turbine is compared with the conventional single blade 0 overlap and 0.2 overlap Savonius turbines, by carrying out the experiments in the open irrigation canal of size 42 cm x 45 cm. Results shows that, the efficiency is improved from 16 % to 19% and the torque values increased along the angular positions of 90°, 120°, 270°, 300°, 330°. From the observations, it has also been noted that, the modified four bladed Savonius turbine rotates smoothly in comparison with the conventional Savonius. The negative torque a common problem in conventional Savonius is also effectively eliminated in the modified design.

Rotor performance enhancement via localized pitch control and its effects on hub vibrations and pitch link loads

This paper presents an approach to enhance rotor performance and reduce vibration levels at the rotor hub by introducing local blade pitch variations at specific azimuthal locations. Two different variants of these “localized pitch control” (LPC) functions are presented and their effects both on rotor performance and vibrational loads are studied using parametric variation and subsequent numerical optimization of the respective LPC signals. The results are compared with those obtained from a conventional approach using 2/rev higher harmonic control (HHC). Numerical calculations were performed using the DLR’s comprehensive rotor code S4 with a modified Beddoes inflow-model simulating an isolated hingeless rotor at an advance ratio of µ = 0.382. In those simulations power reductions of up to 7.61 and 3.36% could be reached using two sets of different model rotor blades. Both for power reduction and simultaneous reduction of power and 4/rev vibrational loads, LPC performed slightly better than conventional 2/rev HHC but also resulted in higher actuation demands which have to be taken into account for real-world applications of LPC.

Numerical and experimental investigation of wind loadings on vertical axis wind turbine blade deflection

This work focuses on experimental and numerical investigation of the deflection on VAWT blade surface against the high measured wind speeds that were simulated in FLUENT to obtain the corresponding static forces. The effect of forces, blade setting angle and thickness to chord ratio along with their combined effects on deflection were assessed experimentally and numerically. Three airfoils of gradually increasing thickness to chord ratio, NACA 0015, 0021 and 4412, were selected along with three levels of forces and tested at 5°, 10° and 15° of blade setting angle. A 33 factorial experimental design was used to perform experiments and Analysis of variance (ANOVA) confirmed that individual effects of force and thickness to chord ratio were the most significant factors while blade setting angle had lesser significance on deflected values. However, interactive effects of these parameters were significant. Minimum deflections were observed in the range of 0.25-0.28 mm on NACA 0021 at 3 kg force in combination with all blade setting angles. Maximum observed value of defection was 1 mm, which occurred at 9 kg force at 5°, 10° and 15° of blade setting angle on NACA 0015 and 4412 airfoil shapes. The results ensure that the blade structure remains stable at 9 kg which corresponds to 20 m/s wind speed without affecting the performance. The deflections obtained from Finite element method were compared with experimental results and found in good agreement with each other.

Vortical Sheet Behavior in the Wake of a Rotor in Ground Effect

Particle image velocimetry measurements with high spatial resolution were conducted on a hovering two-bladed rotor system operating in ground effect above a planar surface. The objective was to gain a better understanding of the fluid dynamics of the wake sheets trailed behind rotating blades, with specific focus on their contribution to the development of the near-wall flowfield at the ground plane. Two blade sets were tested: 1) a baseline untwisted blade and 2) a twisted blade with 17 deg of nose-down linear twist. Planar particle image velocimetry measurements were made for multiple regions of interest in the rotor wake to understand the temporal development of the wake sheets as they convected from their origin at the trailing edges of the blades until they interacted with the ground. The wake sheets were shown to contain relatively large amounts of concentrated vorticity, which persisted much longer in the wake than for the corresponding out of ground effect case. The wake sheet substantially influenced the nature of the developing flow over the ground, resulting in relatively large and higher transient excursions in the near-wall flow velocities further inboard and closer to the rotor. Performance measurements were also taken for both blade sets at various heights above the ground, with the untwisted blades showing the most significant increase in performance.

Etymology of Squiligee and Squeegee

Squiligee is a historical spelling of the name for a scraping implement with a rubber-edged blade set on a handle. Variant forms include squilgee, squilagee, and squillage. The instrument is better...

Exit-Slot Orientation on Pumping Blades for a Rotor in Ground Effect

High-resolution particle image velocimetry measurements were taken to document the evolution of the tip vortices trailed from a rotor system operating in ground effect, with centrifugal-driven (i.e., pumping) spanwise blowing blade designs. All pumping blade designs used the same intake and internal slot, with exit slots oriented at angles of 0, 30, 45, and 60 deg above the horizontal axis. Each blade set was tested in a hovering state in ground effect at a blade loading coefficient of 0.080. Additional measurements were also performed to examine the effect of mass flow rate on tip vortex diffusion. Each pumping blade designs incurred a power penalty, resulting in part from the increased profile losses associated with the exit slots. The 30, 45, and 60 deg pumping blade designs had a degraded performance when compared to that of the 0 deg pumping blade, which was hypothesized to result from negative thrust effects. At the higher thrust condition, the tip vortices trailed from the pumping blade designs persisted in the wake as concentrated regions of vorticity, and at older wake ages, produced relatively similar flowfields. However, at the lower thrust condition, the tip vortices were found to be significantly more diffused.

A case study on the calibration of the k–ω SST (shear stress transport) turbulence model for small scale wind turbines designed with cambered and symmetrical airfoils

This work presents a calibration study of the k–ω SST turbulence model for small scale wind turbines. To accomplish this, two different sets of blades were designed, built, tested and simulated. The first set applied the NACA 0012 and the second the NACA 4412 airfoil. The numerical investigation was taken using the CFD (computational fluid dynamics) code OpenFOAM and the turbulence model was calibrated testing several values for the β∗, including its canonical value, 0.09. The numerical calibration (the main contribution of this paper), extended previous results, which stated that different β∗ values could calibrate the k–ω SST turbulence model for small wind turbines, mainly for the drag effects. The study broadened this conclusion, once the model was calibrated for a quite wide range of tip speed ratio values, from the turbine startup (λ = 0) until its highest experimental value (λ ≅ 8). As a secondary contribution, the results show that the model could be adjusted to simulate average field data, even though these being subject to its inherent variabilities. The main conclusion was that, for the sets of blades studied, the lowest RMSE value was obtained for β∗ = 0.27.

Introducing an Appropriate Mechanical Way for Coconut Dehusking

Coconut (Cocos nucifera L.) is a perennial tree crop, which has a percapita consumption of 120 nuts/ year/ head in Sri Lanka. Nut is the most important economical part in a coconut palm. Fruit has to be de-husked before any production process and there is no any mechanical mean, available in Sri Lanka other than manual coconut de-husking with an iron spike. This has become a major problem in coconut industry, as it is laborious, dangerous and expensive. This study was aimed to introduce an efficient and affordable mechanical method for coconut de-husking. Main components of the de-husking machine are; set of blades and blade spreading system, operating lever system and adjustable fruit holder. The most salient feature of this machine is detaching the husk into four pieces while retaining the soft eye covering part. Machine weighs 65kg and the total cost of production was LKR 13,200. The performance of the de-husking machine was evaluated separately using a single operator (T1) and an operator with a helper (T2) and compared it with most practicing manual de-husking method (de-husking with iron spike). According to the analyzed results by one way analysis of variance (ANOVA), there is a significant difference (p<0.05) between T2 and the manual method but no significant difference was observed between T1 and the manual method. Actual capacities of T1, T2 and the manual method were 69, 135 and 78 nuts/ hr, respectively. Theoretical machine capacities of T1, T2 and manual method were 107, 164, 105 nuts/ hr, respectively. Efficiency of the machine with T1, T2 and the manual method were 64.5%, 82% and 74%, respectively. Therefore, the coconut de-husking machine could be effectively utilized using operator with a helper for a higher capacity and machine efficiency.

A Review of Electromagnetic Activity in Cellular Mechanics

This is a review of recent literature concerning electromagnetic effects on cellular mechanics. “Recent” refers primarily to papers published in this (the 21st) century. The review shows that there are relatively few papers on cellular electromagnetics as compared with those on proteins, biochemistry, and cellular anatomy. The principal finding of the reviewed papers is that cellular electromagnetic fields appear to arise from longitudinal vibrations of the filaments making up the walls of the microtubules. Microtubules are long hollow cylinders which form the overall structure of the centrioles. The microtubules, and therefore the centrioles themselves, are arranged in nine sets of parallel blades with each blade having three microtubules. The centrioles occur in pairs perpendicularly to each other. During mitosis (cell division) the centriole pair becomes two pair which then separate and divide the cell into two. It seems that electromagnetic forces play a central role in this division. Electromagnetic activity in wound healing and in the imaging and treatment of tumors is discussed.

The use of mathematical optimization means to increase the efficiency of a seven-stage axial flow compressor

The paper describes a method of computer-aided redesign of axial flow compressor blades. The method is based on the combined use of the NUMECA computational fluid dynamics software package and the IOSO program optimizer. The basic idea of the method is that, at each iteration, the optimizer generates a variety of parameters that determine the compressor’s geometry. Finite-element models of a compressor are created on its basis in the NUMECA AutoGrid program. The parameters of operation in one or more points on the characteristic of the compressor are calculated in the NUMECA Fine / Turbo program with their help. The calculation results are transferred to the optimizer, where the obtained values are compared with the specified limits. Then a new set of input data is formed. The cycle is repeated until the required criteria of the compressor operation are achieved. The developed method was tested on a seven-stage high-pressure compressor of the NK36-ST engine. The article describes the constructed numerical model and the results of the verification by comparing the calculated data with the experimental data. The model developed makes it possible to obtain results close to the experimental ones and does not require large computational resource. The optimization of the compressor was carried out in two versions using the developed model: 1) increasing the efficiency of the operation mode with the rotation frequency of the rotor of 100% of the maximum by changing the blade setting of the first three stages, 2) improving the efficiency of the two operation modes with the the rotation frequency of the rotor of 80 and 100% of the maximum due to changing the blade setting. It is shown that in the first case the compressor efficiency can be increased by 0.3%. In the second case, the efficiency can be increased by 1.2% at the rotation speed of 80% and 0.5% at the speed of 100% just by changing the blade setting.

Effect of Leading-Edge Tubercles on Compressor Cascade Performance

Tubercles are modifications to the leading edge of an airfoil in the form of blunt wave-like serrations. Several studies on the effect of tubercles on isolated airfoils have shown a beneficial effect in the poststall regime as reduced drag and increased lift, leading to a delay of stall. The prospect of delaying stall is particularly attractive to designers of axial compressors in gas turbines, because this leads to designs with higher loading and therefore higher pressure rise with fewer number of stages. In the present study, experiments were performed on a cascade of airfoils with a NACA 65209 profile with different tubercle geometries. The measurements were made over an exit plane using a five-hole probe to compare the cascade performance parameters. Additionally, hot-wire measurements were taken near the blade surface to understand the nature of the flow in the region close to the tubercles. Oil-flow visualization on the cascade end wall reveals the flow through the passage of blades with and without tubercles. For the cascade considered, the estimated stall angle for the best performing set of blades is found to increase up to 8.6 deg from that of the unmodified blade of 6.0 deg. Application of such structures in axial compressor blades may well lead to suppression of stall in axial compressors and extend the operating range.

Numerical study on a modified impulse turbine for OWC wave energy conversion

Impulse turbine is used in recent times as a self-rectifying turbine in OWC wave energy convertor. It has been found from field test data in Indian OWC plant that the profiles of air flow velocity is not symmetric in exhalation and reverse directions. The velocity is higher during the exhalation (chamber to atmosphere) than in the reverse direction. The modification proposed in this paper is to set the rotor blade pitch asymmetrically with a non-zero value of setting angle. It is expected to give a better performance in a wave cycle under the above air flow conditions. A 3D CFD model based on Fluent is validated by corresponding experimental data and is used for the numerical simulation of the turbine performance for different setting angles under steady conditions. All the calculations were carried out under the steady conditions. Pseudo-sinusoidal velocity pattern was used to represent the realistic air flows in the pilot plant. Quasi-steady analysis was then employed for calculating the mean efficiency for a certain variation of air flow velocity with time during a wave cycle. The clear flow separations were found at the suction side near the trailing edge and the high velocity domain occurs at the suction side near the midstream flow path. The pressure distribution show similar characteristics on both pressure and suction sides. Input coefficient, torque coefficient and mean efficiency are calculated for evaluating the turbine performance under various rotor blade setting angles. For the typical value of 0.6 for the ratio of velocity amplitude at inhalation to that at exhalation, the rotor blade setting angle of 5° was found to be optimum for the modified impulse turbine to achieve the best mean efficiency in a wave cycle.