Tube Design Research Articles

Weight optimization of 200 mm diameter rocket motor tube using finite element method

The lightweight design of the rocket motor tube is a critical requirement for enhancing the rocket's flight performance. This study assesses the impact of wall thickness, cap thickness, and fillet radius on structural strength and the optimization of rocket motor tube weight using the finite element method with the assistance of Ansys software. A total of 12 finite element model variations, utilizing Aluminium 6061-T6, were developed and subjected to a uniform internal operating pressure load of 10 MPa. The design includes wall thickness variations of 8 and 10 mm, cap thickness options of 25 and 30 mm, and fillet radius dimensions of 20, 25, and 30 mm, allowing for a comprehensive comparison to achieve the required minimum safety factor while minimizing structural weight. The research concludes that increasing the fillet radius is a more recommended approach compared to increasing wall thickness and cap thickness. The results indicate that Model 9, with wall thickness, cap thickness, and fillet radius dimensions of 10 mm, 25 mm, and 30 mm, respectively, is the optimal choice due to its lightweight construction.

The use of variable coil pitch of helical tube on the hydro-thermal performance improvement

The use of helical tubes in heat transfer appliances is desirable due to their better heat transfer characteristics, but the higher pressure drop decreases the overall performance. The variation of pitch design of a helical tube is proposed to alleviate this situation so that the pitch number does not remain constant in the total tube length. A total of six variable pitch numbers with three different diameters are proposed and investigated on the thermal and fluid characteristics. To better understand the helical tube efficiency, PEC (performance evaluation criteria) is selected as a performance indicator in the present work and simulations are performed in a laminar regime (100 ≤ Re≤ 1600) at a constant heat flux boundary condition using computational fluid dynamics. The numerical results show that variable radial pitch has higher effects on the overall performance than variable axial pitch, and it can intensify the helical tube performance by up to 10%. The results also indicate that increasing the tube diameter leads to heat transfer and friction factor increment while increasing the Reynolds number deteriorates the overall performance.

Proposal of a control scheme for testing a centrifuge-based pellet injection system in DIPAK-PET

The envisaged Pellet Engineering Testbed (PET) in the framework of Direct Internal Recycling Integrated Development Platform Karlsruhe (DIPAK) will provide unique opportunities to advance pellet injection technology and its implementation in the fuel cycle as well as into plasma control of EU-DEMO. This work analyses the parameters for Pellet Launching System (PLS) control according to requirements from plasma control. Main parameter is the particle flux and the related accuracy with respect to amount of flux and arrival time of pellets. Others are addressed as well like dynamic response to setpoint changes and adaptivity of isotope composition of the hydrogen ice. The performance of the PLS is limited by the mass loss in the guiding tubes, both by erosion (applies to any pellet) and loss of an entire pellet, that may apply to only a few pellets, provided a suitable guiding tube geometry is selected depending on the required injection speed. DIPAK-PET has to provide data points in order to enable proper guiding tube design activities based on modelling. A short description of the proposed technical solution for the Pellet Launching System is provided and setup for the Programmable Logic Control (PLC) is suggested comprising a MasterPLC and a dedicated Human Machine Interface (operators’ desk). A non-exhaustive proposal of experiments to be performed in DIPAK-PET is listed in order to verify the estimated performance values for the relevant PLS parameters.

Design and Analysis of a Cardioid Flow Tube Valveless Piezoelectric Pump for Medical Applications.

Piezoelectric pumps play an important role in modern medical technology. To improve the flow rate of valveless piezoelectric pumps with flow tube structures and promote the miniaturization and integration of their designs, a cardioid flow tube valveless piezoelectric pump (CFTVPP) is proposed in this study. The symmetric dual-bend tube design of CFTVPP holds great potential in applications such as fluid mixing and heat dissipation systems. The structure and working principle of the CFTVPP are analyzed, and flow resistance and velocity equations are established. Furthermore, the flow characteristics of the cardioid flow tube (CFT) are investigated through computational fluid dynamics, and the output performance of valveless piezoelectric pumps with different bend radii is studied. Experimental results demonstrate that CFTVPP exhibits the pumping effect, with a maximum vibration amplitude of 182.5 μm (at 22 Hz, 100 V) and a maximum output flow rate of 5.69 mL/min (at 25 Hz, 100 V). The results indicate that a smaller bend radius of the converging bend leads to a higher output flow rate, while the performance of valveless piezoelectric pumps with different diverging bends shows insignificant differences. The CFTVPP offers advantages such as a high output flow rate, low cost, small size for easy integration, and ease of manufacturing.

Structural design and crashworthiness analysis of expanding-splitting circular tubes

The use of expanding-splitting circular tubes was proposed to improve crashworthiness and overcome their deficiencies in terms of low energy absorption and poor stroke efficiency in a single deformation mode. Quasi-static experiments and finite element simulations were conducted to study the force–displacement response of circular tubes under combined deformation modes. A theoretical model of the circular tube during expanding-splitting deformation was established to reveal the coupled expanding-splitting deformation and energy-absorbing mechanism of the circular tube. Furthermore, the factors influencing key parameters were analyzed using the finite element model. The results showed that the behavior changed smoothly from splitting deformation to curling deformation when adding preformed notches to the circular tube, and the final platform force of the circular tube decreased when increasing the transitional radius. Compared with the traditional expansive structure, the combined energy absorber offers better energy absorption with a 78% increase in platform force.

Solar photovoltaic-thermal system with novel design of tube containing eco-friendly nanofluid

In photovoltaic (PV) solar systems, electricity can be produced from part of the sunlight and the remaining energy raises the temperature. The aim of the current investigation is to suggest a novel design for the heat transfer tube's (HTT) cross section for overcoming this challenge in photovoltaic/thermal (PVT) systems. In this numerical simulation, the range of fluid inlet velocity (Vin) was set between 0.01 and 0.18 m/s. The value of ambient temperature (Tamb) and fluid inlet temperature (Tin) is 30 °C, and solar radiation (G) has been adjusted to 800 W/m2. A comparison was made between the circular tube and the 8-lobed tube with the same hydraulic diameter, and the better performance of the 8-lobed tube was proved. To meet the increased efficiency of the PVT system, copper fins with four different arrangements were employed. The highest efficiency occurred when the fins were placed all around the inside of the HTT. To create heat transfer fluid (HTF), non-toxic graphene nanoplatelets (GNP) have been mixed with water involving two weight fractions (0.025 % and 0.1 %). Examining the effect of changing the fluid inlet velocity (Vin), it was concluded that the system's electrical performance is increased by 5.8 %, with rise of Vin, in the best case. By using the GNP nanoplatelets (0.1 %), at Re = 1611, the maximum exergy, electrical, and thermal performances of the unit were 15.32 %, 14.05 %, and 55.22 %, respectively, in the best case. In the best case, more carbon dioxide (about 7.1 Tons) can be reduced and the carbon credit is 5.5 % higher than that of base case. In addition, the payback period is less than 2 years in the best case with 18700$ profit in the 10th year.

Hydrothermal and entropy generation performance of convergent tubes with various dimple shapes

This paper introduces a comprehensive study on the hydrothermal and entropy generation performance of convergent tubes designed with different dimple shapes. The effects of the dimple shape on the flow characteristics (heat transfer and friction) are investigated using validated computational fluid dynamics (CFD) numerical modelling and simulation tools. Inside convergent tubes with different dimple designs, turbulent flows are subjected to a continuous heat flux of 40 kW/m2. Dimpled tube geometries of different diameter ratios (DR) were built within ANSYS-Fluent software (V2022 R2). Four different dimple shapes were investigated: (a) spherical, (b) cylindrical, (c) conical, and (d) stepped-conical. These dimple shapes were examined to investigate the optimal configuration with the best hydrothermal and entropy generation performance. A comparison is made against the baseline straight smooth tube case. The main performance indicators for comparison are Nusselt number (Nu), friction factor (f), and thermal enhancement factor (TEF), calculated for different Reynolds numbers, Re = 3000 to 40,000, and at different diameter ratios, DR = 1 to 2. In addition, thermal, viscous, and total entropy components, the Bejan number (Be), the enhanced entropy generation ratio (Ns,en), and the irreversibility distribution ratio (φs) are evaluated based on the selected geometrical configurations. The results showed that the dimple shape significantly affects the hydrothermal and entropy generation characteristics of convergent tubes. The best average value of the TEF was attained by convergent tubes with stepped-conical dimple shapes at DR = 1.75, which represents a 7.81% increase over the reference smooth tube (the maximum TEF value is 1.3243 at Re = 3000 and DR = 1.25). Furthermore, the minimum levels of Ns,en were achieved by tubes with stepped-conical dimples, with average reductions of 36.92% over the studied Re range. The study provides valuable insights into the design and optimization of convergent tubes with various dimple shapes for various applications.

Design, Fabrication, and Application Study of Droplet Tube Based Triboelectric Nanogenerators

The invention of triboelectric nanogenerators (TENGs) provides an effective approach to the sustainable power of energy. Liquid-solid interface-based TENGs have been researched in virtue of less friction for harvesting energy from raindrops, rivers, and oceans in the form of water flows. However, TENGs based on droplet tubes have been rarely investigated. In this study, we proposed a new droplet tube-based TENG (DT-TENG) with free-standing and reformative grating electrodes. Both straight and curved DT-TENGs have been designed and fabricated including straight and curved TENG at different inclination angles. The electric properties of DT-TENGs have been evaluated and different materials and hydrophobicity treatments for the tubes have been studied. Initial studies on different liquids demonstrated significant electricity output differences to recognize polar and nonpolar solvents. This DT-TENG was also made into a smart fishing float that can recognize different movement speeds brought about by different weights and generate corresponding electric signals to remind the angler. Furthermore, flexible PVC helix TENG demonstrated similar performance under both straight and helix situations. This study provides a foundation and academic insight into the design and fabrication of droplets based TENGs for energy harvesting in smart cities.

An exploratory gallery for Luka tunnel on the D3 motorway

The Luka tunnel is designed for the 0302 Jílové – Hostěradice section of the D3 motorway. This has a length of 1843m and will consist of two tunnel tubes of T 9.5/100 category. It is proposed that a 1354m long exploratory gallery be put in place in the left-hand tunnel tube. It will be used for detailed geotechnical exploration in a rock environment that has been negatively affected by past mining activities. The exploratory gallery will be constructed using a procedure that will limit the possible stability risks during its excavation. The knowledge gained from the excavation of the gallery and from the comprehensive survey operations undertaken will serve as the essential basis for the reliable design and safe construction of the tunnel tubes. The current state of the D3 motorway differs greatly along its individual sections. The more southerly located sections D 305/II (Nová Hospoda) to D 309 (Úsilné) are in operation. Section D 310 Úsilné – Hodějovice with the České Budějovice bypass is under construction, and the construction in the direction of Austria has not yet proceeded [1]. The situation is very disappointing particularly in the Central Bohemian region, even though exploration operations are underway to a limited extent in sections D 301 to D 305/I, as construction has not yet started due to problems with obstructions or objections by activists of various types. The problem is that it is demonstrable that the existing road I/3, which is also part of the main international road route E55, is already completely inadequate both in terms of capacity and in terms of its alignment running through several developed residential complexes. After the completion of the D3 motorway, this road will be usable as an alternative diversion route without major modifications in the event of a required closure of the motorway.

Design and processing behavior of large tubes with a rotating magnetic pole core-based magnetic abrasive finishing

Design and processing behavior of large tubes with a rotating magnetic pole core-based magnetic abrasive finishing

Optimal Concentric Tube Robot Design for Safe Intracerebral Hemorrhage Removal.

The purpose of this paper is to investigate the geometrical design and path planning of Concentric tube robots (CTR) for intracerebral hemorrhage (ICH) evacuation, with a focus on minimizing the risk of damaging white matter tracts and cerebral arteries. To achieve our objective, we propose a parametrization method describing a general class of CTR geometric designs. We present mathematical models that describe the CTR design constraints and provide the calculation of a path risk value. We then use a genetic algorithm to determine the optimal tube geometry for targeting within the brain. Our results show that a multi-tube CTR design can significantly reduce the risk of damaging critical brain structures compared to the conventional straight tube design. However, there is no significant relationship between the path risk value and the number and shape of the additional inner curved tubes. Considering the challenges of CTR hardware design, fabrication, and control, we conclude that the most practical geometry for a CTR path in ICH treatment is a straight outer tube followed by a planar curved inner tube. These findings have important implications for the development of safe and effective CTRs for ICH evacuation by enabling dexterous manipulation to minimize damage to critical brain structures.

Performance analysis of novel dew point evaporative cooler with shell and tube design through different air-water flow configurations

The complex design of a dew point evaporative cooler (DPEC) is the largest impediment to the globalization of such a high-performance system. Therefore, in this paper, we introduce a new design for the DPEC which eliminates the complexity barrier and significantly improves the system's performance. The new design consists of one shell and a bank of tubes. The single shell works as a working channel, while the tubes work as primary channels. A solid mathematical model has been developed which can predict the system's performance with high accuracy, as it was validated against three experimental studies. Throughout the analysis, the energy and thermal performances of the current model has been compared to the conventional DPEC with flat plate design for two air-water flow configurations, namely, parallel and counter air-water flow configurations. It was found that, under a wide range of operational and geometrical conditions, the new cooler consistently outperformed the flat plate type cooler by producing colder air by about 3.1 °C and improving energy efficiency by about 12.2 %. Meanwhile, the parallel air-water flow configuration produced much colder water than the counter configuration, accounting for 15.76 °C (140 %) colder.

Numerical analysis of a novel coaxial annular tube convective heat switch

Heat switches are commonly used in cryogenic instruments to provide thermal contact or isolation between the hot and cold masses over a temperature range from millikelvin to room temperature. This study presents a new type of convective thermal switch that implements an annular tube design replacing the twin-tube structure. To study the effects of geometry and operating parameters on thermal performance, a computational fluid dynamics (CFD) model is developed. The results show that the designed heat switch provides a thermal conductance of 33.79 mW/K when the end temperatures are 4.2 K and 40 K. In addition, it can automatically change to thermal isolation mode with a residual thermal conductance of 0.19 mW/K. The thermal conductance is increased from 33.79 mW/K to 38.90 mW/K by extending the length of the inner tube. This novel heat switch holds promise for precooling the modern cryogen-free dilution refrigerator (DR) and adiabatic demagnetization refrigerator (ADR).

Dynamics of unipolar charged particles flowing through a cylindrical tube at high number concentrations

This work provides a theoretical and non-dimensional numerical analysis of the dynamics of gas-borne unipolar charged particles flowing through a cylindrical tube at high number concentrations. It is discovered that above a threshold input particle number concentration, the concentration at the exit of the tube is nearly constant and independent of further increase in the input. Based on a maximum of 2% sensitivity of the system, the threshold input number concentration is quantified for a tube of any length more than 40 × the radius. The theoretical analysis developed in this work is used to derive correlations for the threshold input concentration and the exit concentration, as well as show that the exit particle concentration is lower than the threshold input value by a factor of 20/PD, where PD is the well-known diffusive particle penetration. The analysis demonstrates that a constant concentration can occur if and only if the ratio of non-dimensional electric particle mobility to the Gormley-Kennedy diffusion parameter is above 74, which is a hitherto unexplored regime of charged aerosol flow dynamics. It is shown that the constant concentration can occur in compact tube designs (L/R<100) as long as the mass Peclet number of the particles is high and reducing the mass Peclet number to around 10 or below makes it impossible to obtain an input-independent number concentration. It is also shown that the Reynolds number of the flow has very little effect on the charged transport dynamics, where the order of magnitude of the input-independent number concentration is not highly sensitive to the Reynolds number, provided the system remains laminar. Finally, practical examples for designing instrumentation to generate a constant concentration of charged particles are discussed.

Optimization of Vortex Tube Design and Performance for Cooling Milling Process

The manufacturing process is required to improve cleanliness and reduce environmental pollution and the exploration of natural resources is limited. One of the manufacturing processes is machining, especially the milling process. The phenomenon during the milling process friction occurs when the workpiece is cut by the milling tool, the effect friction between tool and workpiece occurs temperature rise. To reduce the temperature rise of the milling tool during the workpiece cutting process, an effective and efficient alternative cooling is needed through the use of vortex tubes. The research method was carried out using the Computational Fluid Dynamic (CFD) approach and experiments with the use of inlet pressure = 1-5 Bar, and the parameters of variations in valve shape, number of nozzles, and pipe lengths. The overall results of the CFD and experiment of parameters in inlet pressure on the number of nozzles, valve shapes, and tube lengths, have an impact on the increasing inlet pressure, the higher the thermodynamic characteristics that occur in the vortex tube, but there is a loss of outlet pressure in each parameter. The geometry of the vortex tube selected is the number of nozzles 6, valve fillet shape, and tube length of 50 mm, vortex tube can be used for cooling the milling tool with the addition of a flexible hose at a distance of 5 cm from the tooltip.

Study on micro-turbojet engine with high thrust-to-weight ratio

Micro-turbojet engine refers to a closed cycle gas turbine engine with thrust below 500kg and power below 100kW. The performance indicators of domestic products are relatively low, and the main problems of domestic products are low thrust-to-weight ratio, poor reliability, and low heat resistance. The low working efficiency of the components and the short life limit the performance of the aircraft. In this paper, a micro-turbojet engine with a higher thrust-to-weight ratio and higher heat tolerance has been designed. The hollow centrifugal impeller with a built-in skeleton structure is successfully developed. The integrated design of the evaporation tube guide and shaft sleeve diffuser solves the problems of poor stability and high production cost, reduces the heat loss, and improves the overall efficiency. Ceramic matrix composite integral turbine disk makes the engine achieve breakthroughs in thrust-to-weight ratio, reliability, and heat tolerance. In addition, the engine has been tested to prove its feasibility. This paper may offer a reference for the design of micro-turbojet engine.

High‐Temperature Creep Behavior of Selective‐Laser‐Melting‐Fabricated Lattice Structures Inspired from Euplectella Aspergillum

In this study, the lattice‐like arrangement of Euplectella aspergillum is used to derive bionic grid‐stiffened structures in the form of thin tubes. The bionic tubes are 3D printed with AlSi10Mg alloy using a selective laser melting process. High‐temperature creep behavior at 250 °C and stress (0.3–0.7) times yield strength of the tubes is studied under uniaxial constant compressive load. The effect of the stress level, temperature, and tube design on the creep performance and deformation behavior is studied. The creep performance of bioinspired tubes is compared with honeycomb lattice tubes. In the results, the dependence of creep life and creep rate on the design of the bionic tubes is shown. E. aspergillum–based thin tubes show higher creep life and lower creep rate as compared to honeycomb‐based tubes at all stress levels. Also, the creep curves of lattice structures based thin tubes are different than the solid material, especially in the primary and tertiary regions. The fractography analysis shows higher creep life in E. aspergillum–inspired thin tubes is due to the improvement in ductility at high temperature. The stress exponent value in the Mukherjee–Bird–Dorn equation shows that the mechanism of creep is diffusion. Herein, in the results, it is shown that the bioinspiration and additive manufacturing provide an opportunity to design and fabricate advanced iso‐grids structures.

Optimized shape design and thermal characteristics investigation of helically coiled tube type heat exchanger

The effects of the helical coil tube designs on heat transfer characteristics during heating process were conducted by some researchers and confirmed that the conventional helical coil tube was not the ideal shape for important heat transfer. Despite this, there was no published paper that presented the optimal helical coil structure for important heat transfer. Therefore, this work addresses the influence of different helical coil structure designs on heat transfer characteristics and temperature distribution during heating process. The study was performed for three configurations named constant-diameter coil, variable-diameter coil and variable-pitch coil. Based on CFD simulation, the mathematical model was validated with experimental results and show good agreement. The results suggest that the helical coil with variable-pitch gives the best heat transfer performance compared with other helical coil structure. Among all considered designs, the combined properties of the helical coil with variable-pitch were better than that of other helical coil structures. As a result, this work could provide a shortcut method in the selection of the appropriate helical coil immersed or wrapped on the tank which need the high heat transfer.

Design and numerical analysis of a novel argon gas tube to reduce impurities in large size casting crystalline silicon furnace

A novel design of argon gas tube within the silicon casting system was developed employing pipe flow and side jet analysis, which facilitates horizontal ejection of argon gas along the silicon melt surface. The aim was to enhance control over gas flow velocity for removing impurities during large size silicon ingot (1400 kg) growth, with special attention on the edge region of ingot. It was found that the diameter of side-facing outlet holes, when oriented along the corner direction, is about 2 times of that along the side center direction, to achieve an extended jet distance reaching corner region. The gas flow and transport of SiO above the silicon melt surface were studied for the proposed gas tube configuration based on 3D numerical simulations. The simulation results reveal the correlation between argon flow rate and resultant gas velocity at the edge of melt surface, which is consistent with the theoretical analysis, particularly for moderate to high argon flow rates. The numerical simulations demonstrated that the proposed gas tube, equipped with eight optimized outlet holes, outperformed the conventional tube in extracting SiO from both central and corner regions above the silicon melt surface.

Proof-of-concept for a thin conical X-ray target optimized for intensity and directionality for use in a carbon nanotube-based compact X-ray tube.

Carbon nanotube-based cold cathode technology has revolutionized the miniaturization of X-ray tubes. However, current applications of these devices required optimization for large, uniform fields with low intensity. This work investigated the feasibility and radiological characteristics of a novel conical X-ray target optimized for high intensity and high directionality to be used in a compact X-ray tube. The proposed device uses an ultrathin, conical tungsten-diamond target that exhibits significant heat loading while maintaining a small focal spot size and promoting forward-directedness of the X-ray field through preferential attenuation of oblique-angled photons. The electrostatic and thermal properties of the theoretical tube were calculated and analyzed using COMSOL Multiphysics software. The production, transport, and calculation of radiological properties associated with the resultant X-ray field were performed using the Geant4 toolkit via its wrapper, TOPAS. Heat transfer analysis of this X-ray tube demonstrated the feasibility of a 200-kV electron beam bombarding the proposed target at a maximum current of 100mA using a 1-ms symmetric duty cycle. The cathode of the X-ray tube was designed to be segmented into nine switchable electrical segments for modulation of the focal spot size from 0.4- to 10.8-mm. After importing the COMSOL-derived electron beam into TOPAS for X-ray production simulations, radiological analysis of the resultant field demonstrated high levels of intrinsic beam collimation while maintaining high intensity. A maximum dose rate of 17,887 cGy/min was calculated for 1-mm depth in water at 7-cm distance. The proposed X-ray tube design can create highly directional X-ray fields with superior fluence compared to that of current commercial X-ray tubes of comparable size.