Propeller Type Research Articles

Mathematical model of the process of mixing semi-liquid feeds in a device with a propeller

The article considers the issues of using a propeller apparatus for mixing semi-liquid feed mixtures in a mixer with an eccentrically positioned working body in the form of a propeller (screw). Until now, when studying the mixing process, little attention has been paid to the transporting ability of the working body in the form of a propeller agitator. When preparing wet mixtures, agitators with a vertically positioned shaft, which is located in the center of a vertical cylindrical tank, are widely used. When installing the working body horizontally, the propeller having a pumping effect (axial movement), can be used not only for mixing, but also for unloading the finished feed mixture, as well as moving it through pipes over short distances. The existing models of the mixing process do not take into account its stochastic nature. Methods of mathematical description of mixing processes considering the prevailing axial movement of the flow are scarcely developed. The proposed mathematical models make it possible to determine the mixer's performance and the required mixing power. The research was aimed at increasing the effectiveness of preparing a feed mixture in a horizontal mixer of propeller type with an eccentrically positioned working body (screw) and saving energy costs along with raising the productivity. The object of the study was a mixing chamber with eccentrically located working bodies of various diameters (0.2, 0.25 and 0.35 m). During the experiments, the productivity required to drive the motor shaft was determined. It has been experimentally established that increasing the agitator rotation speed from 200 to 400 min-1 with a propeller diameter from 0.2 to 0.35 m and a feed mixture humidity of 84 % leads to an increase in power consumption to 3.5 kW and mixer productivity to 12 m3/h, and the degree of uniformity of feed mixtures is up to 98 %.

A Study on the Propulsion Performance of Hybrid-Driven Underwater Glider Equipped with a Kappel Tip Rake Propeller

In order to solve the problem of the lack of maneuverability of the conventional underwater glider, this paper proposes a hybrid-driven underwater glider equipped with a Kappel tip rake propeller, analyzes the propulsion performance of different types of Kappel tip rake propellers in the wake field of the hybrid-driven underwater glider, optimizes the overall propulsion performance of the hybrid-driven underwater glider, and realizes self-propulsion and gliding with high efficiency and low energy consumption. In the research process, the Schnerr–Sauer cavitation model and the cavitation simulation strategy of VOF two-phase flow were adopted, coupled with the SST k-ω and γ transition turbulence model, and the control calculation error was not more than 3%. Based on the hydrodynamic performance study of the Kappel tip rake propeller, the self-propelled simulation was carried out under the working conditions of 6 kn, 5 kn, 4 kn, and 3 kn, and the gliding simulation was carried out under the working conditions of 1 kn, 0.5 kn, and a glide angle of 12°. The propulsion performance of the hybrid-driven underwater glider with different models of Kappel tip rake propellers was analyzed. It was found that the maximum open water propulsion efficiency of the propeller Kap05 had the largest improvement, which was 3.07% higher than that of the reference base propeller. Under the self-propelled condition, the hybrid-driven underwater glider with the propeller Kap05 had the lowest wake fraction, and the propellers Kap04 and Kap05 had the best propulsion performance in the wake field of the hybrid-driven underwater glider. In the gliding condition, the form of the folding paddle can reduce the gliding resistance generated by the propeller by more than 45% and the gliding negative lift by more than 68%. A moderate tip rake can effectively improve the propulsion efficiency of the Kappel tip rake propeller in the wake field of the hybrid-driven underwater glider, reduce energy loss, and improve the overall performance of the hybrid-driven underwater glider.

The effect of the propellant type size on combustion performance of the multi-nitro ester propellant

The effect of the propellant type size on combustion performance of the multi-nitro ester propellant

Numerical simulation of gas-liquid interface in a blade type propellant tank

Abstract Currently, most of the satellite propulsion systems are mainly on chemical propulsion, and liquid propellant is the necessary power fuel for the propulsion system. The propellant tank of the satellite is a critical unit used to store and manage propellant. The hard core of the blade type tank is the Propellant Management Device (PMD), which serves to provide non entrained propellant for the propulser under specified flow and acceleration conditions during all phases of satellite operation. In this paper, the management performance of propellant under microgravity environment in the tank of a blade type is studied. Using the VOF model, the liquid management performance under microgravity environment in the tank is numerically simulated. The repositioning process is numerical simulated. The good management performance of the tank is verified, and the fluid distribution law is obtained, which can provide guidance for the design of the blade type tank.

Effects of Different Initial Conditions on Combustion Process of Ammonium Dinitramide-Based Energetic Propellant in Straight Nozzle

As a new type of green propellant, ammonium dinitramide (ADN)-based energetic propellants have wide application value and development potential in the field of space propulsion. This paper delves into the intricate impact of varying initial temperatures, pressures, and propellant component ratios on critical parameters, including temperature, combustion rate, and heat release, in the straight nozzle of an ADN-based propellant. The findings indicate that an elevation in both initial temperature and ADN ratio expedites the thermal decomposition rate of ADN, thereby elevating the average temperature in the nozzle. However, the elevation in initial temperature has a negative effect on the overall rise amplitude of average temperature. Furthermore, the initial pressure setting is crucial in determining whether the oxidation reaction of the fuel CH3OH occurs in ADN propellants. When the initial pressure is greater than 10 atm, CH3OH is completely consumed, and the final average temperature is about 2650 K, which increases by 558.89% compared with that at 1 atm. Our work aims to provide theoretical guidance and practical optimization strategies for enhancing propellant performance and optimizing thruster structure design.

Assessment of structural mechanical effects related to torsional deformations of propellers

Lifting propellers are of increasing interest for Advanced Air Mobility. All propellers and rotors are initially twisted beams, showing significant extension–twist coupling and centrifugal twisting. Torsional deformations severely impact aerodynamic performance. This paper presents a novel approach to assess different reasons for torsional deformations. A reduced-order model runs large parameter sweeps with algebraic formulations and numerical solution procedures. Generic beams represent three different propeller types for General Aviation, Commercial Aviation, and Advanced Air Mobility. Simulations include solid and hollow cross-sections made of aluminum, steel, and carbon fiber-reinforced polymer. The investigation shows that centrifugal twisting moments depend on both the elastic and initial twist. The determination of the centrifugal twisting moment solely based on the initial twist suffers from errors exceeding 5% in some cases. The nonlinear parts of the torsional rigidity do not significantly impact the overall torsional rigidity for the investigated propeller types. The extension–twist coupling related to the initial and elastic twist in combination with tension forces significantly impacts the net cross-sectional torsional loads. While the increase in torsional stiffness due to initial twist contributes to the overall stiffness for General and Commercial Aviation propellers, its contribution to the lift propeller’s stiffness is limited. The paper closes with the presentation of approximations for each effect identified as significant. Numerical evaluations are necessary to determine each effect for inhomogeneous cross-sections made of anisotropic material.

Analysis of the mechanical response of solid rocket engine propellant under acceleration shock

The increased-range solid rocket engine of new ammunition often needs to withstand extremely high acceleration overload, leading to damage to the propellant’s structural integrity. To address this issue, this paper constructs a nonlinear viscoelastic constitutive model for the CMDB propellant by using low- and high-strain rate mechanical property tests. Combined with the secondary development of explicit dynamics and numerical simulation technology, the mechanical response of a certain type of solid rocket propellant under different acceleration impacts is analyzed. The results show that under acceleration impact loads, the propellant will compress, rebound, and recover over time, continuously cycling. Its axial displacement, maximum equivalent stress, and maximum equivalent strain exhibit irregular sinusoidal wave-like periodic cycles. Looking at the time when the peaks appear, the time when the maximum equivalent stress appears always lags behind the time when the maximum axial displacement peak appears. Due to the viscous effect of the viscoelastic material of the propellant, the time when the equivalent strain peak appears will lag behind the equivalent stress. Because of the material’s damping effect, both the peak values of the maximum equivalent stress and equivalent strain decrease over time. Under continuous high acceleration impact loads, this viscous damping phenomenon continuously diminishes, and the peak value of the propellant’s axial displacement gradually increases.

Aerodynamic Performance Evaluation of a Coaxial Octocopter Based on Taguchi Method

Abstract The design and optimization of propellers for unmanned aerial vehicles (UAVs) are essential for optimal performance and high efficiency. This study presents a numerical investigation of the aerodynamic performance of coaxial octocopters using openfoam as flow solver. While the aerodynamic performance is affected by many parameters, the current study focuses on four main parameters: the propeller type, the horizontal and vertical separation distances between the propellers, and the ratio between the rotational speeds of the upper propeller and the lower one. To find the minimum number of simulations to be performed within defined limits, and reduce the number of computational fluid dynamics (CFD) simulations that cause high computational cost, Taguchi method was employed. In this study, average thrusts were calculated for the preliminary design of the octocopter by examining an isolated single propeller and dual- and quad propellers taking their rotation directions into account. The Taguchi design matrix revealed that for all cases investigated, the propeller type is the most dominant design parameter followed by the velocity ratio of the upper propeller to the lower one (nU/nL) and vertical (z/D) and horizontal (ℓ/D) orientation of coaxial propellers. However, it was shown that ℓ/D and z/D may play a significant role in vortex formation and pressure fluctuations which should be considered as design criteria for coaxial octocopters associated with flow attributes. The results showed that the aerodynamic performance parameters are not dependent on all the selected parameters, and demonstrated that the selected propeller designs improved aerodynamic performance.

Risk Assessment Using Overpressure and Impulse for Abnormal Explosion of Composite Solid Propellants

In this study, the risks were investigated by probabilistic analysis of the effects on the person and structure located around the composite solid propellant when it explodes abnormally. Two types of solid propellants of different sizes and three TNT equivalents of composite propellants were applied to empirical correlation to derive incident pressure and impulse. These were used in probit analysis, and the effects on the person and structure were quantitatively analyzed to determine the risk of solid propellant explosion. The larger the propellant and the more the TNT equivalent, the higher the incident pressure and impulse. Moreover, the amount of propellant had a more significant effect on the impulse than the incident pressure. The effects of the incident pressure and impulse on human were observed to be greater in the order of probability of ruptured eardrums, death from head impact, death from whole-body displacement impact, and death from lung damage. Furthermore, the effects on the structure were observed to be greater in the order of probability of breakage of window, minor damage, major damage, and collapse of the building.

Influence of Various Flame Temperatures of the Gun Propellant on the Effectiveness of the Erosion Inhibitor and Relevant Mechanisms.

The development of high energy gun propellants faces significant challenges in terms of erosion, partly due to the inadequate effectiveness of erosion inhibitors. In this paper, the influence of quite different flame temperature of five gun-propellants on erosion-reducing efficiency of four representative inhibitors materials (talc/TiO2/ PDMS/Paraffin) were studied in vented erosion vessel tester. From aspects of morphologies and element compositions of erode steel samples, as well as the pressure and heat generated by propellant burning, the relevant erosion-reducing processes and mechanisms were discussed. The results indicated that erosion inhibitors should be appropriately selected according to the type of gun propellant. The erosion of gun propellants having extremely high flame temperature of 3810 K were hardly reduced using talc, TiO2, and PDMS inhibitors, which can generate numerous solid particles aggravating the melt-wipe process. While paraffin exhibits a uniquely positive erosion-reducing efficiency for the gun propellant having a flame temperature of 3810 K, that was attributed to the mitigated melt-wipe process. The inference was further supported by the high-volume cooling gas, resulting from the higher burning pressure of propellants loading with paraffin and excellent heat absorption capacity of paraffin tested with propellants having higher propellant flame temperature. The obtained results indicated that the factors of flame temperature of gun propellants should be taken into the design and composition optimization of an effective inhibitor. This work could provide potential reference for the development of future novel inhibitors, which serves as high energy gun propellants.

The Evaluation of Propeller Boss Cap Fins Effects for Different Pitches and Positions in Open Water Conditions

_ The operation of marine vessels with high efficiency provides a great contribution within the scope of the International Maritime Organization and the sustainable development goals. In terms of the propulsion system, selecting the appropriate propeller is critical to effectively use the engine power installed in marine vessels because the biggest energy losses during transmission occur on the propeller and ship hull. Increasing propeller efficiencies above a certain level is quite a challenge by simply changing the number of blades, pitch, or propeller type. Therefore, various energy-saving device applications, such as propeller boss cap fins (PBCFs), are performed on the ship propeller. The effects of National Advisory Committee for Aeronautics 4415 profile PBCFs which have a different position and pitch angle integrated into the E698 model propeller have been investigated to describe efficiency, vortex, and pressure distributions based on the KRISO very large crude carrier 2 designed hull in this study. The E698 model propeller has been created by the 3D software and the validation has been performed by the computational fluid dynamic solver software based on the reference values of the propeller. The effect of four PBCF applications which have different pitches and positions on the model propeller has been revealed in terms of the efficiency, pressure distributions, and vortexes. Although P45-R45 and P45-R90 PBCF applications are quite close to the E698 propeller in terms of efficiency, no significant efficiency increase has been observed. In addition, the efficiency has decreased considerably in P90-R45 and P90-R90 applications. PBCFs application with P45-R90 has provided superiority to the base model in terms of pressure distributions and vortex formation. However, any improvement has not been achieved in the remaining three designs. Therefore, PBCF applications should be applied quite elaborately based on propeller types. Keywords PBCFs; propulsive efficiency; pressure distribution; vortex

Application of dimension reduction methods on propeller performance prediction model

Efficient and effective prediction of propeller performance, especially for hydrodynamic performance and fluctuating pressure, have always been areas of interest for ship engineers and researchers. With the rapid blooming of machine learning based surrogate models, it is important to identify proper features that can represent crucial information from numerous features of propellers' geometry design. This paper used five different dimension reduction methods to conduct the feature selection process from propellers geometry. The reduced features are then used as inputs for a random forest based surrogate model to predict both the hydrodynamic performance and fluctuation pressure under cavitation. The experiment results on three test propellers showed that dimension reduction methods such as factor analysis, principal component analysis and random forest feature selection could yield a higher precision for the surrogate model compare to using all features or the main features selected by experience, while manifold learning methods such as isometric feature mapping and locally linear embedding were not good at extracting propellers' geometry. This paper innovatively proposes dimension reduction methods that can automatically extract main features from propellers' complex geometry. With these main features selected, Artificial Intelligence models can yield a higher precision on propellers’ performance predication. Furthermore, these dimension reduction methods have high generalization ability on different types of propellers, which enables a smarter and more cost-efficient way for the preliminary design process of ship propellers.

Chinese expert consensus on standardized inhaler device application in stable chronic airway diseases (2023)

Chinese expert consensus on standardized inhaler device application in stable chronic airway diseases (2023)

The impact of curved-tip propeller geometry on hovering drone performance for air quality monitoring

The success or failure of a drone mission depend on several elements, including the drone’s mass and payload, the surrounding environment, the battery’s state, and the propulsion system’s performance. Several studies have been undertaken addressing the propeller performance of this final component, particularly for fixed-wing or quad copter drones with ducted propellers. However, the shape of propeller blades used on tiny civil drones has not drawn as much attention. In this research work, the performance characteristics of a 10 × 4.7-inch curved tip propeller were explored, with the Advanced Precision Composite drone propeller serving as a design reference. This study seeks an alternative to ducted propellers when mass or size limitations prevent their use. The Computational Fluid Dynamics model was confirmed by comparing simulation results to the experimental propeller data source established by the University of Illinois at Urbana-Champaign, starting with a standard type propeller and using thrust coefficient as the key performance indicator. Moreover, the data analysis for the bended tip propeller replicating the well-established model, revealed the benefits as well as the drawbacks of such propellers on the mission profile and the battery lifespan of a quad copter Unmanned Air Vehicle.

Prospects for solving import substitution problems when completing the power plant of ships with water jet propellers

One of the most important problems of domestic shipbuilding is the modernization of the fleet under the sanctions of unfriendly countries. To solve this problem, it is necessary to ensure import substitution of key elements of power plants of vessels and ships. The article is devoted to the review of the current state of design and production of the main elements of power plants of vessels and ships with water jet propulsion. The designs of the main types of water jet propellers used in power plants are described, their advantages are shown. The requirements for the drive engines of water cannons when using them as part of marine power plants are formulated. Based on the analysis of sources of scientific and technical information related to the field of research, the prospects of using water jet propulsion in the creation of high-speed vessels and ships operating in shallow water (lower Volga, inland waterways, coastal waters of the Caspian Sea, etc.) are shown. The technical characteristics of the main elements of power plants (water cannons and engines) produced by domestic enterprises are given. Based on the conducted review of the products of domestic enterprises, a conclusion is made about the possibility of solving the problem of import substitution when completing power plants of vessels and ships with water jet propulsion. The necessity of continuing scientific research and development aimed at upgrading the engine systems used to drive water cannons and the search for alternative designs of drive engines is shown. Particular attention should be paid to the possibility of completing power plants with water cannons with star-shaped engines of domestic production.

Growth mechanism and characteristics of electron drift instability in Hall thruster with different propellant types

The existence of a significant electron drift instability (EDI) in the Hall thruster is considered as one of the possible causes of the abnormal increase in axial electron mobility near the outlet of the channel. In recent years, extensive simulation research on the characteristics of EDI has been conducted, but the excitation mechanism and growth mechanism of EDI in linear stage and nonlinear stage remain unclear. In this work, a one-dimensional PIC model in the azimuthal direction of the thruster near-exit region is established to gain further insights into the mechanism of the EDI in detail, and the effects of different types of propellants on EDI characteristics are discussed. The changes in axial electron transport caused by EDI under different types of propellants and electromagnetic field strengths are also examined. The results indicate that EDI undergoes a short linear growth phase before transitioning to the nonlinear phase and finally reaching saturation through the ion Landau damping. The EDI drives a significant ion heating in the azimuthal direction through electron–ion friction before entering the quasi-steady state, which increases the axial mobility of the electrons. Using lighter atomic weight propellant can effectively suppress the oscillation amplitude of EDI, but it will increase the linear growth rate, frequency, and phase velocity of EDI. Compared with the classical mobility, the axial electron mobility under the EDI increases by three orders of magnitude, which is consistent with experimental phenomena. The change of propellant type is insufficient to significantly change the axial electron mobility. It is also found that the collisions between electrons and neutral gasescan significantly affect the axial electron mobility under the influence of EDI, and lead the strength of the electric field to increase and the strength of the magnetic field to decrease, thereby both effectively suppressing the axial transport of electrons.

Experimental monitoring of CO2 hydrate slurry crystallization by heat flux rate determination in a jacketed reactor

CO2 hydrate slurries are promising phase change materials for secondary refrigeration applications. However, the difficulty of experimentally evaluating the crystallization kinetic of slurries limits their industrial use. Hydrate crystallization kinetics monitoring performs traditionally by a reactor mass balance. However, this method requires assumptions on CO2 liquid phase concentration and the hydration number. This work outlines the development of a specific method to determine kinetics thanks to the direct measure of heat flow through the reactor jacket and its evaluation compared with the mass balance method. The results of each method are then obtained by testing the two kinetic parameters of stirring speed and propeller type. The final hydrate mass fractions obtained with both methods are in good agreement, but the kinetic obtained by the mass balance method is faster than by the heat balance method.

ВЛИЯНИЕ ЧИСЛА НОГ В ДВИЖИТЕЛЕ НА ДИНАМИЧЕСКУЮ НАГРУЖЕННОСТЬ ПРИВОДА ШАГАЮЩИХ МАШИН С МЕХАНИЗМАМИ ШАГАНИЯ ЦИКЛОВОГО ТИПА

The results of modeling the dynamics of walking machines of the "heavy" weight category with cyclic type propellers are considered. The influence of the number of legs (walking mechanisms) in the mover on the structure of power costs spent on movement is revealed. It is shown that an increase in the number of legs in the propulsion system, despite the obvious increase in its inertial characteristics, leads to a decrease in the dynamic load of the drive of walking machines.

On the flow of a bubble pair rising in temperature-sensitive gel propellants

The gel propellant is a novel type of propellant created by introducing gelling agents to the liquid propellant. Similar to other types of propellants, the occurrence of air bubbles in the gels is common and unavoidable during the manufacturing and casting process. The presence of bubbles can adversely impact the stable combustion of the engine and may even pose safety hazards when they enter the combustion chamber. In order to gain a better understanding of the bubble interaction within the gel propellant, we have conducted a study on the motion of a pair of bubbles rising in a quiescent water-gel. In this study, the volume of fluid (VOF) method is adopted for modeling the multiphase feature of the flow. The shear and temperature dependent viscosity of the gel has been modeled using the temperature-coupled Carreau–Yasuda model. The effects of various factors, including the initial distance between the bubble pair, bubble diameters, and the temperature, on the motion characteristics of the bubble pair are studied. It is found that an increase in the initial distance leads to a reduction in the bubble interaction; for side-by-side bubble pairs, the bubbles exhibit slower ascent rates and reduced lateral displacement; for inline bubble pairs, the coalescence of the bubble pair becomes slower. Increasing the diameter of the dominant bubble accelerates the coalescence of the bubble pair and the ascent. Elevating the temperature results in a decrease in viscosity, thereby accelerating the coalescence and ascent of inline bubble pairs and producing viscosity reduction around the bubble pair.

RANCANG BANGUN ALAT UJI THRUST MOTOR BRUSHLESS DENGAN VARIASI PROPELLER

In drone design, the selection of components such as batteries, Electronic Speed ​​Controllers and propellers must be in accordance with the requirements, but not all components in the RC include measurement data to determine the specifications of the brushless motor. Therefore, a test tool is needed that can calculate the amount of thrust or use a tool trials. Brushless motors and propellers are important components that affect flying performance on drones. The greater the thrust generated by the brushless motor and propeller, the greater the load that can be lifted by the drone. The types of propellers commonly used in drones include 6x4, 9x6, and 10x5 propellers. To measure the amount of thrust, load sensors and current sensors can be used which are converted by the ADC HX711 converter. The test bench tool can be used to produce data experimentally using the help of the sensor. In testing the 6x4e propeller produced a current of 7.8 Ampere and a thrust of 1.13 kgf, the 9x6e propeller produced a current of 16.4 Ampere and a thrust of 1.63 kgf, and the propeller 10x5e produced a current of 18.6 Amperes and a thrust of 2.07 kgf with the right selection of brushless motors and propellers, drone performance can increase.