Inlet Diameter Research Articles

Numerical Investigation on Flow Pattern, Heat Transfer and Pressure Drop Characteristics of Flow Boiling with Discrete Heat Sources

Heat dissipation and temperature uniformity are one of the key technologies for electronic equipment. With the rapid growth of computing demand and the wide application of multichip devices, heat sources are distributed discretely in space. Therefore, the flow boiling in the mini-channel with two discrete heat sources is investigated in this study. The effects of heat source distribution, inlet fluid temperature and channel diameter on flow pattern, heat transfer and pressure drop are discussed in detail. The results show that intermittent flow tends to form around discrete heat sources, especially near the heat source which is far from the channel inlet. Moreover, the distance between discrete heat sources shouldn’t be too close to avoid heat concentration, nor too far to make full use of latent heat. When the distance between two heat sources is 70 mm, the temperature distribution is appropriate, and the heat dissipation is the best in this study. For the discrete heat source far from the inlet, the heat transfer coefficient increases significantly when the inlet fluid temperature increases due to the preheating of another heat source.

Parameter Optimization of Centrifugal Pump Splitter Blades with Artificial Fish Swarm Algorithm

Low specific speed centrifugal pumps typically suffer from low efficiency and severe backflow; adding optimally structured splitter blades can play a role. In this paper, the distribution of pressure and velocity in the flow channel is analyzed using CFD simulation for a low specific speed centrifugal pump. The geometric parameters of the splitter blade are optimized using an orthogonal test and an artificial fish swarm algorithm; then the optimal splitter blade structure is obtained. Results showed that the splitter blade not only effectively solves the backflow of the flow channel and compresses the range of the trailing vortex, but it also alleviates the cavitation at the inlet of the main blade. When considering the best head, the order of influence of each factor is: Splitter blade thickness > Splitter blade inlet diameter > Splitter blade inlet width. At this time, the thickness of the splitter blade is 4.5 mm, splitter blade inlet diameter is 155 mm (0.775) and Splitter blade inlet width is 23 mm. Through the closed pump experimental system, it is confirmed that hydraulic performance has been improved.

Modeling of main arteries restenosis in experimental cardiology

Abstract Funding Acknowledgements Type of funding sources: None. Purpose To perform the model of main arteries restenosis and to study the arterial hemodynamics using the original device for modeling of intra-arterial circulation. Materials and methods We used an original device developed by us for modeling of intra-arterial circulation. The main part of the device is a prototype of human arterial vessel - rotameter glass tube 365 mm length, with inlet diameter more than outlet (20 mm vs 16.5 mm). An aqueous solution of glycerin is introduced inside closed system had the same viscosity as the human blood. Flexible silicone tubes are connected with rotameter and electric pump with various modes of work (imitation of pulse waves in regular rhythm (RR), extrasystoles (ES), atrial fibrillation (AF)). We hermetically installed in the rotameter imitation of arterial stent – metal construction with spiral oriented parts 68 mm long. Plastic diaphragms 15 mm long with stenosis of the internal lumen of 50%, 70%, and 90% were alternatively put inside the tube to study intra-arterial hemodynamics. 5 mm long silk thread was alternately installed inside the tube, an intravascular piezoelectric crystal pressure sensor connected to an oscilloscope was injected with a dye - clerical ink. Results When imitating AF after the long pause the speed of fluid flow through the diaphragms increased in comparison with the RR with the pendency: if longer pause was than more speed increased. So, with a stenosis of 50%: the speed with a RR was 2.09 m/s, with AF after the pause <1 s speed was 3.36 m/s, AF after the pause >1, but <2 s speed was 4.97 m/s, AF after the pause >2 s speed was 5.88 m/s; with 70% stenosis: the speed with a RR was 3.24 m/s with AF after the pause <1 s speed was 3.96 m/s, AF after the pause >1, but <2 s speed was 5.87 m/s, AF after the pause >2 s speed was 7.83 m/s; with 90% stenosis, the speed at RR 8.96 m/s, with AF after the pause <1 s speed was 9.46 m/s, AF after the pause >1, but <2 s speed was 11.17 m/s, AF after the pause >2 s speed was 13.45 m/s. The pressure measured by piezoelectrical probe increased proportionally to the speed. We observed the appearance of reflected, standing waves in the edge zones of the diaphragm and stent and a turbulent flow of liquid behind the diaphragm and stent. Conclusion These changes in hemodynamics are characterized by proposed concept of "hydraulic shock". Intense mechanical effect of the pressure waves after the long pauses between cardio cycles in AF in the marginal zones of the diaphragm and intra-arterial stent can cause the further growth, progression of atherosclerosis and restenosis in arterial vessels.

Investigation into fresh air delivery performance with vortex ring

An air supply mode based on vortex ring structures was proposed to deliver fresh air for good indoor air quality. This study focused on the influence of air supply parameters, including formation time (T*), supply air velocity (U0), and supply air temperature difference (ΔT), on the fresh air delivery performance of an air vortex ring using numerical simulations. The cross-sectional average mass fraction of fresh air (Ca) was proposed to evaluate the fresh air delivery performance of the air vortex ring supply. The results showed that the convective entrainment of the vortex ring resulted from the combined effect of the induced velocity generated by the rotational motion of the vortex core and the negative pressure zone. When the formation time T* < 3.5, Ca increases with an increase in the formation time but decreases with an increase in the formation time for T* > 3.5. The variation in Ca is insignificant for U0 < 3 m/s or U0 > 3 m/s but decreases with an increase in the supply air temperature difference (ΔT). Thus, the optimal air supply parameters for air vortex ring supply are identified as T* = 3.5, U0 = 3 m/s, ΔT = 0 °C. Compared with the traditional circular and square free air jets, within 25Ds (Ds: the diameter of air supply inlet) downstream from the air inlet, the fresh air delivery performance of the air vortex ring supply is increased by a maximum of nearly 200 %, with an average improvement of approximately 120 %.

Effect of flow channel structures and refrigerants on the motor cooling process of compressor with gas bearings

Energy-saving and environment-friendly water chiller is the development trend. The efficient compressors and new refrigerants are hot spots. The gas bearing can significantly improve the performance of centrifugal refrigeration compressors, and effective motor cooling is the guarantee of performance and reliability. The influence of channel structure and refrigerant on the performance of the motor cooling process and refrigeration system is analyzed. The results show that adding the bearing gas supply circuit decreases the motor temperature and the maximum variation of permanent magnet temperature is about 60 °C. The cooling channel structure in the interlayer of the motor shell will affect the cooling process. The spiral channel can reduce the stator temperature and improve the uniformity of temperature distribution. But the temperature of the motor changes slightly when the length of the channel is more than 6000 mm. The motor temperature is the highest with refrigerant R1234ze(E), followed by it R1234yf and R134a. The maximum temperature of the permanent magnet for R1234ze(E) is 20–50 °C higher than it for R1234yf and 50–60 °C higher than it for R134a under different inlet diameters. The maximum temperature of the permanent magnet for R1234ze(E) is 30 °C higher than it for R1234yf and 50 °C higher than it for R134a under different inlet temperatures. The system with a motor cooling circuit has controlled the motor temperature within the safe operation range, while the COP of systems with R134a, R1234yf, and R1234ze(E) has only decreased by 4.63 - 5.36%, 4.22 - 4.6%, and 3.78 - 4.15% respectively.

Coiled quarter wavelength resonators for low-frequency sound absorption under plane wave and diffuse acoustic field excitations

To reduce their space requirement, quarter wavelength resonators are coiled up into a spiral to have the shape of a flat cylinder. The practical implementation of these resonators is tested using 3D printing, laser cutting and machining. Numerical simulations and impedance tube measurements are first compared for a normally incident plane wave excitation. This step allows to evaluate the effect of the resonator’s inlet diameter, internal wall thickness, overall height as well as its constitutive material. A series of samples are then 3D printed following the identified optimal geometrical configuration. An array of resonators is tested alone and in combination with a glass wool layer under diffuse acoustic field excitation in a small reverberation chamber. The obtained results show that coiled quarter wavelength resonators can provide large sound absorption at their lowest resonance frequency and under both considered excitations, even if the largest external dimension of the resonators is only 1/18th of the targeted acoustic wavelength.

Analysis on flow structure in a vortex pump under all flow rates

Abstract Vortex pumps are usually designed based on its inner flow model. Currently, the flow models of vortex pump just consider flow rate at the design condition, which results in low efficiency under off-design flow rates in practical engineering. Therefore, the main objective of this article is to build a flow model that takes into account the impact of flow rates. To reveal the flow mechanism of vortex pump, we provide refined flow field simulations for a vortex pump. Performance experiments were conducted to validate the numerical simulation method. The study found that the vortex structure in the non-blade cavity can be regarded as a Rankine-like vortex. The inflow range is limited to the hub diameter (45 mm), smaller than the volute inlet diameter (85 mm). The action radius of the forced vortex gradually decreases from the impeller side to the inlet side. The maximum radius of the forced vortex on the impeller side is determined by the impeller diameter. As the flow rate increases, the action radius of the forced vortex on the inlet side gradually increases, while the axial length of the vortex in the inlet pipe gradually decreases. Based on the study of internal flow, a new flow model is proposed.

Influence of Axial Matching between Inducer and Impeller on Energy Loss in High-Speed Centrifugal Pump

Studying the axial matching between the inducer and impeller is crucial for optimizing the structure of centrifugal pumps. In this paper, the SST k-ω turbulence model is used to analyze the influence of three axial positions on the internal flow and the energy loss of a centrifugal pump. Additionally, the entropy generation method is used to evaluate the energy loss in the pump. Three sets of inducer design schemes are selected based on the ratio of the distance from the trailing edge of the inducer to the impeller inlet and the impeller inlet diameter, which are λ = 0.6, λ = 0.9 (original scheme), and λ = 1.2, respectively. The results indicate that changing the axial position of the inducer between λ = 0.6 and λ = 1.2 has only a negligible effect on the overall performance of the centrifugal pump. At flow rates of 0.6Qd and 1.0Qd, the inlet pressure coefficient of λ2 is significantly lower compared to λ1 and λ3. As the flow rate increases, the pressure coefficient difference between the inlet and outlet in the inducer decreases, which leads to a more uniform streamline distribution and better development of the vortex in the flow channel. The energy loss in the inducer mainly occurs at the rim, the trailing edge, and outlet near the wall. As the flow rate increases, the entropy generation rate at the inducer rim decreases slightly and remains around 1000 W·m−3·K−1. At flow rates of 1.0Qd and 1.2Qd, the energy loss in the impeller reduces as the axial distance increases, with the exception of the flow rate 0.6Qd.

Double chamber meso scale vortex combustor for micro scale electric generator based on thermo electric generator

Research on micro/meso combustor-based small-scale power plants is developing rapidly. This rapid development is motivated by a higher energy density than lithium-ion batteries. In addition, energy needs for portable and mobile devices also drive this development. Based on the opportunities and needs of these small-scale power plants, this study focuses on developing a double-chamber mesoscale vortex combustor. This research aims to compare the temperature profile and the electrical energy generated by single and multiple combustion chambers on the meso vortex combustor. The single chamber combustor has 56 × 28 × 10 mm, and the double combustor is 56 × 56 × 10 mm. Both meso vortex combustor has dimension with a 4 mm inlet diameter. In the meso scale vortex combustor, we also installed stainless steel wire mesh to compare the temperature with and without wire mesh. Based on the numerical study results, the flame can be stabilized in the double chamber combustor configuration. The wire mesh installation can enhance the flame stabilization process. Nevertheless, the wire mesh installation reduces the wall temperature because the mixture’s exit velocity is more stable than the combustor without the wire mesh. The result shows that a double chamber meso scale vortex combustor has a higher temperature and electric energy output than a single chamber combustor. The double chamber combustor can generate 9.5 Watt electric power with 12.6% energy conversion efficiency.

Performance analysis of a gas cyclone with a converging-diverging vortex finder

In this study, the influence of a novel converging-diverging (CD) vortex finder on the performance of a gas cyclone was studied using the computational fluid dynamics (CFD) method. In addition, the influence of the CD outlet pipe on the erosion rate of the cyclone was investigated. The cutoff diameter, pressure drop, and erosion rates of the new vortex finder design were compared with those of the conventional straight outlet pipe cyclone. The throat of the CD pipe was at the same level as the cyclone's roof. The simulation showed that the CD outlet pipe significantly reduced the cyclone pressure drop. The height and diameter of the converging part of the vortex finder affected the cyclone pressure drop and separation efficiency. Increasing the converging part's inlet diameter reduced the outer vortex tangential velocity and the cyclone separation efficiency. Increasing the converging part inlet diameter reduced turbulent intensity at different cyclone levels. The CD vortex finder with the shortest height and inlet diameter of the converging part (model C1) reduced the cutoff diameter from 6.2 µm to 5.9 µm. The CD outlet pipe with the largest height and inlet diameter of the converging part (model C6) reduced the pressure drop by 42.2% compared to the conventional cylindrical vortex finder. The erosion rate also decreased significantly with an increase in the converging part inlet diameter. However, the converging part height only slightly affected cyclone performance.

Sex-specific bone and muscular morphological features in ischiofemoral impingement: A three-dimensional study.

The study aimed to investigate how hip bone and muscular morphology features differ between ischiofemoral impingement (IFI) patients and healthy subjects among males and females. Three-dimensional models were reconstructed based on magnetic resonance imaging images from IFI patients and healthy subjects of different sexes. Bone morphological parameters and the cross-sectional area of the hip abductors were measured. The diameter and angle of the pelvis were compared between patients and healthy subjects. Bone parameters of the hip and cross-sectional area of the hip abductors were compared between affected and healthy hips. The comparison results of some parameters were significant for females but not males. For females, the comparison results of pelvis parameters showed that the anteroposterior diameter of the pelvic inlet (p=0.001) and intertuberous distance (p < 0.001) were both larger in IFI patients than in healthy subjects. Additionally, the comparison results of hip parameters showed that the neck shaft angle (p < 0.001) and the cross-sectional area of the gluteus medius (p < 0.001) and gluteus minimus (p=0.005) were smaller, while the cross-sectional area of the tensor fasciae latae (p < 0.001) was significantly larger in affected hips. Morphological changes in IFI patients demonstrated sexual dimorphism, including bone and muscular morphology. Differences in the anteroposterior diameter of the pelvic inlet, intertuberous distance, neck shaft angle, gluteus medius, and gluteus minimus may explain why females are more susceptible to IFI.

Influence of Valve-Seat Angles to Operation Values and Emissions of Medium-Speed Diesel Engines

Abstract For the development of gas exchange for large diesel engines, a compromise has to be found between efficient valve-flow and the time between overhauls. On the one hand, large effective flow areas, especially during valve-overlap, are demanded. On the other hand, there are limitations of cylinder bore regarding the maximum diameter of inlet and outlet valves and the minimum distance (dead space) between valves and piston, as well as wear-related smaller seat angles. For large medium-speed diesel engines, a valve-seat angle of β = 30° for inlet and outlet valves is a standard application. For engine-operation with clean fuels, a valve-seat lubrication (gasoil) or smaller seat angles (natural gas) need to be applied. With this presentation, the basic influence of different valve-seat angles on the operation values and emissions will be considered for the example of the single-cylinder research engine FM16/24. Using a self-developed testbed, experimental investigations into effective flow areas as a function of valve-lift at inlet and outlet valves have to be executed. With this input, different cycle calculations including T/C have to be carried out to determine deviances in specific fuel-oil consumption, exhaust-gas temperatures, NOx emissions and air/fuel ratio. The results will be discussed critically.

Obstetric pelvimetry by three-dimensional computed tomography in non-pregnant Japanese women: a retrospective single-center study

Objective While a basic understanding of pelvic size and typology is still important for obstetricians, pelvic measurement data for Japanese women are very scarce. To our best knowledge, no large-scale pelvimetry studies of Japanese women have been made for the past 50 years. This study aimed to investigate the accurate size, particularly the obstetric conjugate (OC) and transverse diameter of the pelvic inlet (TD), of modern Japanese women, using three-dimensional (3D) computed tomography (CT), and to obtain their reference values. Methods This retrospective, single-center observational study enrolled Japanese non-pregnant women aged between 20 and 40 years, who underwent pelvic CT examination from 2016 to 2021. CT was performed for various reasons, including acute abdomen, search for cancer metastases, and follow-up of existing disease. However, no cases were taken for pelvic measurements. Pelvimetry was performed retrospectively using a 3D workstation. The OC was measured on a strict lateral view and the TD was measured on an axial-oblique view. Other clinical data, such as age, height, and weight, were also extracted from the medical charts and analyzed. Results A total of 1,263 patients were enrolled, with the mean age of 32.7 years (standard deviation [SD] 6.2). The mean height, weight, and body mass index were 158.8 cm (SD 5.8), 54.8 kg (SD 11.7), and 21.7 kg/m2 (SD 4.4), respectively. The mean OC length was 127.0 mm (SD 9.5, 95% confidence interval [CI] 126.5–127.5), while the mean TD length was 126.8 mm (SD 7.5, 95% CI 126.4–127.2). Both values were normally distributed. Height was significantly associated with OC (regression coefficient = 0.75 [95% CI 0.66–0.84], p < .001) and TD (regression coefficient = 0.63 [95% CI 0.56–0.70], p < .001). Age showed a weak but statistically significant positive association with TD (regression coefficient = 0.14 [95% CI 0.07–0.20], p < .001) and OC (regression coefficient = −0.10 [95% CI −0.18 to −0.01], p = .026). Conclusion The 3D CT pelvimetry in 1,263 non-pregnant Japanese women of childbearing age revealed the mean OC and TD of 127.0 mm, and 126.8 mm, which were 11.8 mm and 4.3 mm larger, respectively, than those in the survey in 1972. Our data will be referred to in clinical practice as the standard pelvic measurement values for the Japanese population.

Bakır ve pirinç elektrot ile EDM yönteminde soğuk iş takım çeliği işlemede MRR, EWR ve KERF Analizi

In this study, holes were drilled on the Sleipner cold work tool steel with a hardness of 60-62 HRC by copper and brass electrodes using three different current values (50, 25, 12.5 A), pulse on times (3, 6, 9 μs) and pulse off times (4, 6, 8 μs) parameters in the EDM method; the effects of these working parameters on machining times, material removal rate (MRR), electrode wear rate (EWR), the hole inlet-outlet diameters of the machined parts, the kerf on workpiece and electrode were analyzed. As a result of the analyzes made, in the use of copper electrodes, the MRR increased by 311.25% on average compared to the use of brass electrodes, while the EWR and machining time decreased by 42.01% and 38.46%, respectively. The increase in sparking and thermal effects between the workpiece and the electrode resulted in an increase in the MRR and a decrease in the machining time. In the use of copper and brass electrodes with different processing parameters, the inlet diameters of the drilled holes were found to be larger than the outlet diameters as well as an irregular kerf formation was observed due to debris evacuation due to worn electrodes.

Influence of an impeller inlet diameter on operation of a high-speed submersible electric pump at the high flow rate modes

BACKGROUND: The study object is a high-speed drainage submersible electric pump, aimed to water polluted sea and fresh water bailing out of drowned rooms of shipbuilding industry facilities.&#x0D; AIMS: To obtain dependencies of pump cavitation properties on relative diameter of an impeller inlet at the high flow rate modes, to determine the kind of head-capacity and energy properties of a pump for various geometrical ratios of an impeller in the flow rate operational range.&#x0D; METHODS: Main geometrical properties of impellers were determined with use of semi-empirical formulas of various authors methods. For the study of dependencies, three options of impellers were chosen and series of fluid dynamic simulations of three-dimensional flow of viscous fluid with use of the ANSYS CFX software were completed.&#x0D; RESULTS: Head-capacity, energy and cavitation properties of the pumping unit were obtained. The experimental head-capacity curve correlates to the simulated one. The simulation results revealed that using of narrowed impeller inlet leads to generation of wide low-pressure area at the backside of the impeller vane and disruption of operational curves at the high flow rate modes. With the biggest relative diameter of the impeller inlet, the vapor pressure area at the backside of the impeller is absent so there is no disruption of operational curves at the high flow rate modes, however, the pump hydraulic efficiency ratio at the whole range of flow rate is the lowest among all the studied options of impellers.&#x0D; CONCLUSIONS: The method of defining the value of an impeller inlet diameter, optimal with regard to energy and cavitation properties, to ensure cavitation free operation of a high-speed submersible electric pump at the whole range of flow rate is proposed.

Parametric study on the internal geometry affecting agricultural air induction nozzle performance

With recent advances in agricultural engineering, precision spraying has become of prime interest to avoid chemical drift or rebound and to minimize water and soil pollution. Air induction nozzles are reliable alternatives for conventional nozzles to overcome these challenges. A parametric study was designed both experimentally and numerically to investigate the effect of each design parameter on the performance of an air induction nozzle. A number of components were designed, manufactured, and tested. The spray structure was captured using a planer Mie scattering imaging system. The mean droplet size was measured using a Malvern particle sizer based on a laser diffraction technique. The results indicated the influence of each geometrical component on the resultant behavior. The internal geometry of the nozzle was found to significantly impact the stability and structure of the spray such as the fluid behavior inside the nozzles and the air-to-liquid mass flow ratio, as well as spray angle, droplet size, and uniformity. The key findings of this study indicate that pre-orifice inlet diameter primarily controls the flow behavior, air, and liquid inlet diameters of the ejector section impact mainly on the air-to-liquid mass flow ratio, the geometry of the mixing chamber mainly controls the stability of the resulting spray, and the geometry of the flat-fan tip essentially controls the spray angle and droplet size. The results can help nozzle designers optimize the design target, enhance atomization efficiency, and understand the effect of the various design parameters on the internal flow behavior of air induction nozzles.

Study on the thrust fluctuation and vortices of a pump-jet propulsor under different duct parameters

Improving underwater propulsor performance is endlessly pursued, not only the propulsion but the vibration and radiated noise. The latter is highly related to the unsteady characteristics of forces and flow. This paper investigates the effects of duct parameters on the thrust fluctuation and flow features of a pre-swirl stator pump-jet propulsor (PJP) via embedded large eddy simulation (ELES). The duct parameters include inclination angle, tip clearance, axial length, maximum thickness, and diameters of duct inlet and duct outlet. The numerical approach is verified with experiments, showing good precision. The performance is first discussed, followed by the thrust fluctuation analysis to reveal the varying law of the thrust fluctuation level with duct parameters. Then, the velocity and pressure around the duct are presented to inspect the causes of differences in performance and thrust fluctuation. Finally, the vortices in the flow field are identified and considered the vortex evolution of the tip clearance vortex for inspecting the instability mechanism under different ducts. Results show that the duct parameters significantly affect the performance and thrust fluctuation. The instability mechanism of the tip clearance vortex also presents notable differences. Overall, the study should be helpful in the duct design and reduce thrust fluctuation, and will eventually benefit low-noise pump-jet design.

Effects of Surge Tank Geometry on the Water Hammer Phenomenon: Numerical Investigation

A surge tank, as one of the most common control facilities, is applied to control head pressure levels in long pressurized pipelines during the water hammer occurrence. The cost-effective operation of surge tanks is highly affected by their characteristics (i.e., surge tank diameter and inlet diameter of surge tanks) and can effectively reduce the repercussion of water hammers. This investigation utilized the method of characteristics (MOC) in order to simulate the behavior of transient flow at the surge tank upstream and the head pressure fluctuations regime for the hydraulic system of a hydropower dam. Firstly, the MOC model was validated by experimental observations. The various types of boundary conditions (i.e., sure tank, reservoir, branch connection of three pipes, series pipes, and downstream valve) were applied to investigate the simultaneous effects of the surge tank properties. In this way, all the simulations of water hammer equations were conducted for nine various combinations of surge tank diameter (D) and inlet diameter of surge tank (d). The results of this study indicated that for the surge tank design with D = 6 m and d = 3.4 m, head pressure fluctuations reached the minimum level in the large section of the pipeline which is the surge tank upstream. Additionally, the occurrence of the water hammer phenomenon was probable in the initial section of the pipeline.

Particle Image Velocimetry of 3D-Printed Anatomical Blood Vascular Models Affected by Atherosclerosis.

Improvements in the diagnosis and treatment of cardiovascular diseases facilitate a better understanding of the ongoing process. The study of biomedical fluid dynamics using non-intrusive visualizing methods on a micro-scale has become possible using a proper 3D printing process. The computed tomography scan of a patient with atherosclerosis was processed, and a 3D-printed artery with an inlet diameter of 4.2 mm was developed and measured using three different constant flow rates. To mimic blood, a solution of glycerin and water was used. The procedure to obtain a proper 3D-printed model using low-force stereolithography technology with high-quality optical access usable for PIV was described and discussed. The paper presents the results of PIV as multi-stitched, color-coded vector maps from the axis cross section along the whole 3D-printed model. The obtained data allowed a resolution of 100 × 100 µm per single vector to be achieved. Furthermore, the results of the stitched 16 base images of the artery and the 3D-printed model prepared were included. The results of this study show that 3D prints allow for the creation of the desired geometry and can be used to investigate severe pathologies of the human circulatory system. The strengths and weaknesses of this methodology were discussed and compared to other techniques used to obtain transparent objects.

Design of Venturi-Type Fertilizer Injectors to Low-Pressure Irrigation Systems

Twenty prototypes of Venturi-type fertilizer injectors for low-pressure agricultural irrigation systems were designed based on functional hydraulic pressure head and variation of their structural designs. These prototypes were modelled in three dimensions (3D) and evaluated using simulation through Computational Fluid Dynamics software (CFD). The main structural design characteristics come from a real necessity to complement an low pressure multigate irrigation system project named in Spanish &amp;ldquo;El Manzano&amp;rdquo; (The Apple tree) and bring it the fertigation possibility. The aim of this research was to select the best prototype, in order to identify the convergent and divergent angles, throat diameter and hydraulic pressure head to efficiently produce a Venturi-type injector for use in gated-irrigation pipe irrigation systems for use in a future in &amp;ldquo;El Manzano&amp;rdquo; project. As a result of the simulations, the physical characteristics of the injector were defined. The inlet and outlet diameters should be 152.4 mm, the throat diameter 76.2 mm and the suction diameter of 50.8 mm. The convergent and divergent angles showing most improved performances were 7.5 and 10&amp;deg;, respectively. This methodology can be used to construct Venturi-type fertilizer injectors for low-pressure gated-pipe agricultural irrigation systems, which, on one side, can reduce significantly the fertilizer application costs and, on the other side, the fertilizer management efficiency can be also improve considerably to save water resources. There is relatively very little experience in using this type of fertilizer injectors in low-pressure irrigation systems.