Blade Type Research Articles

Influence of uneven blade tip clearances on aeroacoustic characteristics of centrifugal compressors

The blade tip clearance is a crucial factor in the compressor performance and the aeroacoustics. There are usually main blades and splitter blades, two different types of blades in centrifugal compressors. Keeping almost the same work input, three different tip clearance configurations were designed in which the tip clearance gaps of main blades and splitter blades were uneven. Then experimental investigations were carried out to study the influence of uneven tip clearances on the aeroacoustic characteristics of centrifugal compressors. The results showed that larger main blade tip clearances or larger splitter blade tip clearances would induce rotating instabilities (RI) near flow instability boundary at low rotating speeds. However, the broadband noises below the blade passing frequency (BPF) in the case with uneven blade tip clearances were suppressed significantly which might be due to the incongruous interaction between the tip clearance leakage flows of main blades and splitter blades. In addition, the blade nonsynchronous vibrations (NSV) were observed in the analysis of the frequency spectrum of far-field noise in the case which had smaller main blade tip clearances and larger splitter blade tip clearances. Based on the jet core feedback theory, a physical explanation was given for NSV occurred in this case.

Theoretical and experimental research on the coating process of ceramic stereolithography

The coating process in ceramic stereolithography is one of the principal sources of inaccuracy in the height dimension. The coating in stereolithography is a layer-by-layer build-up process, so the thickness of one layer coated is influenced by the previous layer and affects the thickness of the next layer. If inconsistent layer thicknesses exist, they will result in the poor quality of the final product. This paper analyzes the coating process of the slurry-separated system based on a simple 2D model and Navier-Stokes equations, presenting the theoretical equations of layer thickness for the commonly used blade types. Given the characteristics of layer-by-layer coating in stereolithography, the theoretical equations should be constantly iterated to obtain the thickness of each layer. This paper discovers the initial blade gap has a significant impact on the layer thicknesses by theoretical analyses. With the verification of experiments, the results shows that the presence of the unreasonable initial blade gap may lead to large fluctuations in layer thicknesses of the first few layers, and the coating in stereolithography is a "self-regulating" process with a tendency to the desired thickness. The larger the desired layer thickness, the worse this "self-regulating ability" is. This paper defines a coefficient of blade gap and proposes that using the coefficient of blade gap to determine a reasonable initial blade gap based on different working conditions can effectively control the consistency of each layer thickness.

Propeller selection optimization on mini LNG ship based on engine propeller matching approach

Mini LNG Carrier Ship is specially designed for the purpose of distributing Liquefied Natural Gas (LNG) throughout Indonesia and supporting the national program of generating 35.00 MegaWatt (MW). Indonesia’s vast territory with long distances requires an efficient transportation, including Mini LNG Carrier Ship to reduce costs, especially fuel and emission levels that meet the EEDI criteria set by the International Maritime Organization (IMO). One of the efficiency factors of Mini LNG Ship Carrier is obtained by optimizing the design, especially to the propulsion system. The propulsion system consists of the main engine and propeller. This study focuses on the selection of ship propulsion propellers, especially the type and number of propeller blades. The good propeller will have an impact on the level of energy efficiency. The research method used is a computational simulation using the Engine Propeller Matching (EPM) method. The study tested the B-Series propeller with an alternative number of propeller blades are (z) = 3, 4, 5, 6, and. 7. Calculating simulation results show that the analysis of the EPM computational results at 10 knots service speed, shows that the B6.40 propeller has a better efficiency value than the other propeller types (z = 3, 4, 5, and 7). Propeller type B6.40 produces a good level of efficiency according to the planned 2 x 250 KW engine performance diagram.

Structure parameter design and bench test research of paddy field blades

Aiming at the problems of high labor intensity and low efficiency in manual operation during the pulping process of rice seedling nursing in thin mud in hilly and mountain areas, this paper designed a new type of paddy field blade for seedling nursing, and utilized a rice nursery pulper to help manual operation complete the pulping process. It created a mathematical model of mud-throwing mass and operating power in the operation process of paddy field blade, and obtained the main structure factors that influenced the mud-throwing mass and operating power of paddy field blade, which included the area of mud splashing board, the angle between the front cutting edge and the mud splashing board, and the inclination angle between the front cutting surface and the mud splashing board. To further analyze the degree of influence of the blade’s main structure parameters on mud-throwing mass and operating power, it used EDEM discrete element simulation software to establish a discrete element simulation model of paddy field blade and mud particle system, performed simulation analysis with the method of orthogonal experimental design, and conducted a bench test for comparison. The results showed that: (1) the degree of influence of the three structure parameters on mud-throwing mass and operating power from large to small in order was the area of mud splashing board > the inclination angle between front cutting surface and mud splashing board > the angle between front cutting edge and mud splashing board; (2) the maximum relative error for mud-throwing mass between simulation analysis and bench test was 4.53%, and that for operating power was 8.67%; and (3) three reference parameters combinations were selected by P2-1/M2 graph, the mud-throwing mass of the three combinations was 40.43%, 27.52% and 0.16% higher than that of the original blade, and the power consumed was 13.99%, 21.83% and 36.65% lower than that of the original blade, indicating that the new paddy field blade had good operating performance.

Rancang Bangun Bilah Berbahan Expanded Polystyrene (EPS) Foam untuk Kecepatan Angin Rendah pada Produk Horizontal Axial Wind Turbine

The increasing use of electrical energy is inversely proportional to the diminishing fossil energy sources. New and Renewable Energy is one of the alternative energy that is being developed now. One of the energy used in the utilization of new and renewable energy is wind energy. In this study, we will discuss the manufacture of blades made from Expanded Polystyrene (EPS) Foam which is intended for wind turbines at low wind speeds. The use of this material is used and is able to form a blade with a weight of ± 300gram. This blade uses an Inverse Tapper type blade, which is a blade with an enlarged geometry at the tip, this geometry has a large surface so that it can receive more wind so that it can rotate at low wind speeds. The design and manufacture of blades is carried out using Aeolus ASP software which is open source on several analysis features and serves to determine the performance of the blades as well as to analyze aerodynamics and optimization of the shape of the blades designed to use Blade Element Momentum (BEM). This blade is capable of producing a voltage of 12.09 V. In the process of making the blade using wire cut to create geometry with National Advisory Committee for National Aeronautics (NACA) 4412 airfoil. The blade uses layers of balsa wood and monocote plastic sheets, and uses wood plywood as the base of the blade.

​​Selection of a Cutting Mechanism and Optimization of Parameters for Coconut Harvesting Drone

Background: Coconut (Cocos nucifera L.) palm is an important cash crop in India and third-largest producer of coconut in the world. In general, the skilled workers climb to harvest the coconuts from the tree without any safety device. The coconut trees are very tall and injuries associated with coconut tree climbing, particularly falling from coconut trees is common in coconut plantations. In order to rectify the problem, an appropriate cutting system needs to be developed. Hence the characterizing physical and mechanical properties viz., peduncle thickness, width, shape, size, moisture content, density and also the cutting blade characteristics, were studied. Methods: The observed characteristics were used for the effective design of the cutting module. The cutting blades were selected for the investigation viz, circular saw blade and saw tooth blade. The parameters selected for the investigation are cutting speed (S) at three levels (15.70, 20.94 and 26.17 ms-1), the inclination angle of the blade (q) five levels (30, 45, 60, 75 and 90°), type of the blades (B) (regular tooth and ripped tooth pitch) and thickness of peduncle (T) three levels (30, 40 and 50 mm). Similarly for chain saw, the velocity of cutting speed (S) at three levels (500, 700 and 900 rpm), the inclination angle of blade (q) at three levels (45, 60 and 90°) and thickness of peduncle (T) three levels (30, 40 and 50 mm) were selected for the experiments. Result: The optimization of the selected levels of variables was done to achieve best performance to select the cutting speed, cutting angle and type of blade. The results showed that circular saw blades with irregular tooth pitch have higher cutting efficiency than circular saw blades with regular tooth pitch. It was found that cutting time increases linearly with decreasing cutting speed. It was observed that chainsaw gives better cut quality with minimum cutting time than saw blades.

Review of the Typical Damage and Damage-Detection Methods of Large Wind Turbine Blades

With global warming and the depletion of fossil energy sources, renewable energy is gradually replacing non-renewable energy as the main energy in the future. As one of the fastest growing renewable energy sources, the safety and reliability of wind energy have been paid more and more attention. The size of modern wind turbines is becoming larger and larger. As the main component of wind turbines to capture energy, the blade is often damaged by various complex environments and irregular loads. Therefore, the health monitoring and damage identification of wind turbine blades have become a main research focus. At present, in addition to the overview of various detection methods of wind turbine blades, there is a lack of comprehensive classifications and overviews of the main damage types, damage-generation mechanisms, and basic principles of the damage-detection technology of wind turbine blades. In this paper, firstly, the common fault types of wind turbine blades, such as trailing edge cracking, lightning strike, leading edge corrosion pollution, icing, and delamination, as well as their generation mechanism, are comprehensively analyzed. Then, the basic principles and the latest research progress of the current main detection technologies, such as vision, ultrasonic, thermal imaging, vibration, acoustic emission, and so on, are comprehensively reviewed. The advantages and limitations of the various detection technologies for practical application are summarized. Finally, through a comparative analysis of the various damage-detection technologies, we try to find potential future research directions, and draw conclusions. This paper will provide a reference for understanding the mechanism behind the main damage types and the damage-detection methods of wind turbine blades. It has important reference value for further promoting practical research of wind turbine blade damage-detection technology and grasping this research direction.

Effects of electromagnetic-vibration fan with folding blades on convective heat transfer

The electromagnetic-vibration fan is mainly composed of a pair of vibrating blades and an electromagnetic drive device. The electromagnetic force drives the blades to vibrate periodically, generating airflow for cooling electronic equipment. Optimising the fan blades at the same power consumption is a critical way to enhance convective heat transfer. The present work designed a new blade type with a three-dimensional groove structure, the folding blade, based on the rectangular blade. The effects of the electromagnetic-vibration fan with folding blades on convective heat transfer were investigated experimentally and numerically. The results show that the folding blade can increase the vorticity and air velocity. In comparison with the rectangular blade, the maximum airflow velocity increases by 0.9 m s−1, and the time-averaged and maximum temperatures decrease by 2.5 °C and 1.6 °C, respectively. The optimal folding number, folding depth and length of the free-end section are 7, 2 mm and 25 mm, respectively.

Study of the parameters of the field of the cone-shaped working body straw chopper

State program of developing agriculture of Uzbekistan is directed to the developmend of important field - animal husbandry and its suppiy with roug-hage, in the framework of creating small cattle-breeding, farming and peasantry, that demand a special attention at prearing high guality roughage at small material expenses. The practice showed that unsatisfactory processing of rousgh fodder stalka by fodder preparation machinery bring to quality dectine of got fodder and accordingly to the inerease of its loss (to 30 %). The authors proposed and developed a rotary straw chopper with cone-shaped working bodies. The diameter of a working body and an angle of a blade of a knife are theoretically investigated. To substantiate the type and parameters of the chopper blade, a stand for laboratory research was developed and manufactured. Change of cutting force and cutting power consumption depending on circumferential cutting speed, straw diameter, knife length and blade inclination angle were studied by experimental researches. On the basis of experimental studies the type and optimum parameters of rotor and knife were established: knife type - disc; rotor diameter 172 mm; number of knives 4; knife inclination angle 20°.

Hemodynamic Responses to laryngoscopy and intubation: Comparison between Macintosh and McCoy laryngoscope

Background: Laryngoscopy causes exaggerated hemodynamics as tachycardia, hypertension, arrhythmias and may have deleterious respiratory, neurological, and cardiovascular effects. A very few studies have compared the effects of various types of laryngoscope blades on hemodynamic response to laryngoscopy and intubation. Methodology: A prospective randomized study was done to compare the hemodynamic response to using McCoy and Macintosh laryngoscope. A hundred patients, belonging to ASA grade I and II, between 15-65 years, requiring general anesthesia with intubation were included. A standard anesthesia technique was used. Both groups(n=50) were matched demographically. Mallampati grading, laryngoscopy and intubation time, laryngeal visualization grades, and hemodynamic variables at baseline were comparable. Result: Following laryngoscopy there was significant rise in heart rate, systolic, diastolic and mean arterial pressure. The maximum change in HR compared to baseline was 20.45±9.29 vs 12.36± 7.28 (p<0.001) in Macintosh and McCoy groups. As compared to baseline maximum change in SBP (mean) was 7.92±10.53 vs 2.80± 6.73 (p= 0.005), the maximum change in DBP (mean) was 9.28±14.74 vs 5.72±7.37 (p= 0.130), the maximum percentage change in MAP (mean) was 8.62±12.07 vs 4.36±7.83 (p=0.039) in Macintosh and McCoy group respectively. Compared to variables just before insertion of the laryngoscope, maximum percentage rise in mean HR was 22.74±10.88 vs 16.40±7.43 (p=0.001), maximum percentage rise in SBP (mean) was 28.31± 13.22 vs 19.41±6.82 (p<0.001), maximum percentage rise in DBP (mean) was 30.00±15.25 vs 24.64±12.21 (p=0.003), maximum percentage rise in MAP (mean) was 28.89±11.55 vs 22.31±11.34 (p=0.05) in Macintosh and McCoy group respectively. Conclusion: The hemodynamic response to laryngoscopy and intubation with McCoy laryngoscope was significantly less than with Macintosh laryngoscope.

The study on the influence of the injected flow swirling on the characteristics of the jet pump

of this paper is to analyze the possibility of increasing the efficiency of wellbore jet pumps by twisting the injected flow. The absence of moving parts, easy transfer of energy, the ability to operate a wide range of performance and low cost have resulted in the use of ejection systems in many oil and gas deposits. The main disadvantage of borehole ejection systems is the insufficient value of the jet pump efficiency. The energy efficiency of downhole jet pumps can be improved by swirling the mixed flows. To characterize the effect of circulating flows was used an additional factor in the form of the values of the inclination angle of guiding elements that swirl the flow or the rotation frequency of jet pump elements. In the process of determining the values characterizing the operating process of ejection systems, the flow rates of the working and injected flow and the pressure values in front of the nozzle, the receiving chamber and the chamber at the outlet from the diffuser of the jet pump are subject to direct measurement. Swirling of the injected flow was carried out by placing a sleeve with guiding elements, manufactured using 3D printing technology, in the receiving chamber of the jet pump. The analysis revealed that in the design of downhole jet units, there are used guiding elements, mainly the screw, blade and tangential type, to swirl the flow. A highlighted list of factors that have a direct effect on the flows mixing process. During experimental studies of swirling injected flow type jet pump characteristics, there is obtained an increase in pressure and energy parameters. The task of further research is to determine the characteristics of a downhole swirling injected flow type jet pump for conditions of combined swirling of the working and injected flows. The obtained results make it possible to take into account the presence of guiding elements in the flow path of the jet pump for swirling the flow. It is established that the relationship between the design and technological parameters of the local swirling of the mixed medium is determined by the ratio of rotating and axial components of the flow velocity in the flow path of the jet pump.

ANALISIS GAYA DORONG (THRUST) PROPELLER PADA PESAWAT MODEL REMOTE CONTROL (UAV)

Unmanned aircraft or known as UAV (Unmanned Aerial Vehicle) is an aircraft technology that is controlled ly by the operator using Control. The thrust is determined according to the needs of the aircraft itself. This study uses a thrust test stand that uses a mass measuring device as a measuring force, using a brushless motor and 3 different types of propellers, namely propeller two with a size of 8 x 4 inches and 10 x 7 inches, three propellers with a size of 6 x 3 inc to determine the optimal thrust for missions flying -controlled model aircraft (UAV). After testing, it was found that the smallest thrust force of the 6x3 inch blade type propeller, on this type of propeller only 3,874 N of thrust is produced at 100% throttle percentage and uses a 3 cell battery. While the greatest thrust generated from the propeller with a type of two when 10x7 inches, on this propeller and using a 4 cell battery can produce a Thrust of 13,194 N with a percentage of full throttle or 100%. The thrust required for the aircraft to fly cruising in the air is 0.806 N, while the thrust required for the aircraft to take off is 6.513 N.Keywords: Control Model Aircraft, Propeller, Thrust

Performance investigation of ultra-high pressure ratio cryogenic turboexpanders for helium liquefaction system

Availability of ultra-high pressure ratio turboexpanders present numerous options to the helium liquefier/refrigerator designer as it allows to conceptualize a compact plant by making use of high-pressure process compressors and eliminates placement of turboexpanders in series for large pressure heads in the process cycle. Setting out with this objective, a new series of cryogenic turboexpanders comprising of two high pressure ratio variants has been developed at Bhabha Atomic Research Centre (BARC). These turboexpanders are designed using the Enhanced midstream design method (EMDM) which has been reported by the authors earlier. Enhancement of pressure ratio of these variants from the earlier reported value of 4 to the new value of 6 is achieved through redesigning the inlet nozzle. For each variant of the turboexpanders, two types of inlet nozzle are designed using the EMDM. Type ‘A’ is based on an aerofoil section with ideal blade loading and type ‘B’ is based on a non-aerofoil section and non-ideal blade loading distribution. These remodelled, ultra-high pressure ratio variants of the turboexpanders are experimentally investigated using the BARC developed helium refrigerator CP1000.

Enhancing the aerodynamic performance of a Savonius wind turbine using Taguchi optimization method

ABSTRACT Savonius wind turbines are a type of vertical axis wind turbine. In this research, the effect of some design parameters such as blade type, overlap ratio, separation distance, and blade thickness on the aerodynamic performance of a two-bladed Savonius wind turbine with the rotor diameter of 0,3 m was investigated numerically by using a realizable k-epsilon turbulence model. Three different levels were selected for each parameter. Computational fluid dynamics analyses were performed using Fluent software and the Taguchi method was used for the optimization process. It was seen that a Savonius rotor with an elliptical blade that has a 2 mm thickness, a 0,15 overlap ratio, and a 7,5 mm separation distance shows the best aerodynamic performance. The difference between the aerodynamic performances of the base and the optimized rotor was found to be greater at higher tip speed ratios than at lower tip speed ratios. The power coefficient was raised by nearly 17,9% for a tip speed ratio = 0,8. The optimal tip speed ratio value was changed from 0,8 to 1,0, after the optimization process.

Development and performance evaluation of a wet-resistant strip-till seeder for sowing wheat following rice

Seedling establishment is critical for grain yield and net benefits of wheat in wet clay soil after puddled rice harvest in the Yangtze River basin (YRB) of China. A wet-resistant rotary strip-till seeder (WR seeder) was developed to drill seeds in zero tillage (ZT) conditions with complete rice residue mulching. The rotary blades adopted were medium radius C type blades creating a 50–60 mm wide and 30–50 mm deep furrow for seed placement. The pressing roller, usually used in the traditional wheat seeders, has been replaced by two ground wheels covered in rubber to reduce the mud adhesion. Moreover, a stainless-steel chain was installed behind the machine for better seed covering with soil. Based on three-year long field comparisons with the traditional deep tillage seeder (DT seeder) and a rototiller disc-type seeder with shallow tillage (SHT seeder), the six-row WR seeder significantly enhanced seedling establishment, and reduced energy consumption by 51.3% and 24.5%, respectively. The WR seeder also conserved the topsoil moisture. Over three years, the WR seeder produced similar grain yield to the SHT seeder, but 3.1% more than the DT seeder. Moreover, the net profit with WR seeder increased by 39.4% and 0.9% compared to the DT and SHT seeders, respectively. Furthermore, comparisons across the YRB also confirmed the positive effects of the WR seeder on grain yield and economic benefits over the conventional seeding practices. Thus, it was demonstrated that the improved seeder is an optimal option to enhance the RW system productivity in the YRB. • A strip-till seeder was developed for wheat sowing in wet clay fields. • Yield superiority and energy efficiency with the improved seeder were demonstrated. • The wheat yield increase resulted from the large increase in fertile spikes. • Effective residue management enhances the seeder performance.

Determination of the Force Required to Produce Stab "Wounds" in Fruit Compared With Cadaveric Chest Tissue.

In laymen's terms, it can be difficult to communicate how much force is needed to create a stab wound into a person's chest. Previous work has determined the force to puncture the skin, rib cartilage, or bone but without putting the results in terms that are easy to understand.The purpose of this study was to determine the force needed to puncture 3 types of fruit using 3 different types of knives, namely, a steak knife, a butcher's knife, and a lock-blade knife, to help put these previous results in perspective.There was wide variation in the force required to insert a knife into different fruits, but no force for any knife at any location for all fruits exceeded 93.1 N. Results show that force needed to penetrate the skin and allow for an 8-cm blade penetration into the chest is similar to the force required to insert a steak knife for a 6-cm distance into a cantaloupe. In addition, the force needed to penetrate the cartilage is most similar to stabbing a watermelon to 6 cm with a butcher knife. However, the forces required to penetrate the bone are greater than those required to penetrate any fruit with any type of blade.

Experimental investigation of the effect of a novel curved winglet vortex generator on heat transfer with a designed controller circuit

In the presented experimental study, twelve different double-sided curved blade vortex generators were produced at two blade angles (15° and 30°) based on the turbulator blade angle, blade direction, and the placement of the turbulators in the pipe. After conducting smooth pipe studies, the curved structure's winglet components were mounted on the pipe at various angles and locations, and the effects on heat transfer and pressure drop were determined for Reynolds Numbers ranging from 16,210 to 41,470. The smooth pipe results obtained were compared with the results obtained from the numerical Gnielinski, Dittus-Boelter, Blasius, and Petukhov equations. In addition, a control circuit has been developed to ensure the precision and recording reliability of the results. The root mean square error (RMSE) and mean absolute percent error (MAPE) results obtained by the controller circuit were found to be in good agreement with the results of the experimental study. Considering the results obtained with the elements placed in the pipe, the highest increases in Nusselt number and friction factor compared to the smooth pipe were 173% and 592%, respectively. The most notable Nusselt number (Nua/Nuo) and friction factor (fa/fo) increases were seen in the values of 3.41 and 6.92, respectively. The highest PEC value for the heat transfer improvement effect was approximately 1.79 for the low Reynolds Number value of 16,214. Among all the turbulators, the highest heat transfer increase was achieved with the double-sided opened blade (UD-30) type turbulator, while the lowest heat transfer increase effect was achieved with the one-bladed opened type (OC-15) turbulator. In terms of PEC, eight turbulators had a significant effect on all Reynolds values, but the remaining four had no effect.

Thermal characterization of straight and curve edge blade liquid fuel swirl burner

Accurate monitoring and controlling of the temperature in the combustion chamber can raise the burner efficiency, combustion intensity, fuel consumption and reduce pollutant emission. However, except combustion is accurately monitored and controlled, high concentration of pollutant gases and products like carbon monoxide (CO) and soot can form in the combustion chamber. This paper compares the combustion thermal profiles in a liquid fuel swirl burner using developed straight edge and curve edge blade swirlers at (20, 30, 40, 50 and 60)° for 6, 8, 10 and 12 number of blades in order to optimize the temperature of the burner. Measurements were made in straight and curve blades liquid fuel swirl burner in order to study and compare the thermal characteristics of the straight and curve edge blades in optimizing the combustion dynamics. Similarly, measurements were made for burner without swirl generator and the combustion temperature assessed. Thermal profile was measured in the direction of flow via the six axial ports at distance ((d) =150, 350, 550, 750, 950 and 1150 mm) from the burner exit using Chromium-Zinc thermocouple. Results showed that the wavelength and oscillation of temperature decay in the same type of blade followed the same trend and the peak of combustion intensity is nearer the nozzle for curve edge blades than the straight edge blade. Six (6) blades performed best with the highest temperature in all the ports, while 12 blades gave the least performance. Findings further show that curve edge blade swirlers gave better performance than straight edge blade swirlers with highest temperature of (1065 and 1015) °C, respectively. Hence, it is recommended especially where high temperature and stability application is desirable

Bionic Optimization Design and Experiment of Reciprocating Cutting System on Single-Row Tea Harvester

The reciprocating cutting system is one of the key parts of a tea harvester; and its cutting performance directly determines the cutting power consumption and harvesting quality of the machine. Because the structural parameters of reciprocating cutting systems do not match the tea cut; resulting in larger cutting resistance, it is necessary to optimize the structural parameters. The cricket mouth part has outstanding performance in tea tree fiber cutting; and the curved structural characteristics of the upper jaw of the cricket have been useful to improve the cutting efficiency of cutting system. Quantitative analysis of the structure of the upper jaw revealed that the arc-shaped structure of the incisor lobe would inspire new bionic blades and bionic cutters to solve the above problems. The cutting performance experiment of the cutting blade was designed for investigating the effects of inter-node number; tea variety and blade type (ordinary blade; bionic blade e and bionic blade f) on the cutting force and cutting power consumption. Experimental results of cutting performance have shown that the bionic blade could reduce cutting resistance and cutting power consumption. Tea varieties had little effect on cutting force and cutting power consumption. In addition, the orthogonal test was carried out to study the influence of cutter type with the cutting speed ratio and cutting angle on the integrity rate and missing rate of tea shoot. The field cutting experiment showed that the cutting angle was the most important for the integrity rate and missing rate of tea shoot; followed by the cutter speed ratio; and finally, the cutter type. The optimum combination of parameters was a cutting speed of 0.8 m/s; a forward speed of 1.0 m/s; a cutting angle of −3°, and using the bionic cutter e. With the optimal parameter combination, the integrity rate and missing rate of the tea shoot were 92.7% and 3.9%, which were increased by 13.2% and decreased by 6.4% compared to those under the condition of the 0° cutting angle and an ordinary cutter. As a result, the bionic cutter could obviously reduce cutting resistance; reduce cutting power consumption and improve the harvesting quality. These results would provide guidance for the design of the reciprocating cutting system of tea harvesters and other stalk cutting machinery.

A CFD-PBM Coupled Method to Optimize a Pilot-Scale Stirred Bioreactor

The stirred bioreactor is the core equipment in the biological fermentation industry. This work studied the influence of blade structure and operating conditions on the bioreactor performance by the population balance model (PBM) coupled computational fluid dynamic (CFD) method. The results indicate that increasing the stirring rate can improve the gas hold-up in the pilot-scale reactor but falls insignificant compared to the ventilation intensity. In addition, the Sauter mean diameter exhibits negative correlation with the unit power and is larger in the upper part of the reactor than that in the lower part. Comparative analysis with four types of blades shows that the Rushton turbine (RT) blade contributes to the better gas hold-up and dispersion performance under the same stirring rate while consuming the highest unit volume power of 2.957 W/L. Therefore, optimizing the blade structure is beneficial to improve the mixing performance and reduce the energy consumption of the bioreactor. This work examined the extent to which CFD models could be used as an efficient tool in the hydrodynamic analysis of the stirred bioreactor.