Propeller Type Research Articles

Autogiros: Review and Classification

The article reviews autogiros, concentrating on their flight history, development, application, flight principle, components, and advantages over other aircraft. Firstly, the history of autogiros is presented, focusing on breakthrough inventions and clarifying their significance for overall rotorcraft development. Then, contemporary scientific research on the autogiro is reviewed in detail, and the available research gap is determined. The flight principle and technical fundamentals of autogiros are also briefly discussed, and a comparison between autogiros, helicopters, and fixed-wing aircraft is performed. Autogiros’ applications for civil, military, and mixed purposes are pointed out and schematically presented. The main part of the article comprises an overview of the different components and systems in the structure of the reviewed aircraft, including the main rotor, propeller, engine, cockpit, and others. Additionally, a comprehensive classification mostly concerning contemporary and homologated autogiros is described and schematically presented. Experimental and compound gyroplane designs are also examined and marked in the classification. The aircraft are categorized depending on the main structure type, mast availability, number of seats, number of rotors and rotor blades, rotor and mast position, propeller and tail type and position, pre-rotator type, and power source. The idea of different autogiro variants presented in the classification is enhanced with visual examples. This work is an addition to the efforts of promoting autogiros and research on them. It offers complete information regarding the aircraft and could serve as a kind of starting point for engineers in the design process of such types of flying machines.

Investigation of propeller configuration effects on the flight stability of unmanned aerial vehicles

This study investigates the flight stability of unmanned aerial vehicles (UAVs) by comparing two-, three-, and six-blade propellers. The experiment uses a self-made drone with a 3D-printed polylactic acid (PLA) frame and an Arduino-based flight control system to create an efficient UAV prototype. The flight tests are conducted in a controlled environment, eliminating flight confounders such as wind and temperature, and the three types of propellers are of similar size. Stability was assessed by measuring deviations in the drone’s X and Y axes while hovering within ±30 degrees, and standard deviation (SD) was calculated to quantify variability. The tests revealed that propeller count significantly impacts stability and overall performance. The three-blade propeller provided the best stability, with the smallest SD in the X-axis at 10.85 and Y-axis at 11.85, and showed the least deviation over ±30 degrees during take-off and flight. While the 2-blade propeller has the least stability in flight, with a value of 15.08 in the X-axis and 16.3 in the Y-axis, showing a deviation exceeding ±30 degrees several times throughout the test, the 6-blade propeller demonstrates intermediate performance, with a value of 12.71 in the X-axis and 15.57 in the Y-axis, which is more stable than the 2-blade propeller but still less stable than the 3-blade propeller. The results of this study provide UAV design data by studying the factors in selecting propellers with different numbers of blades for drones, presenting information on the importance of propeller selection for drone flight performance and stability. The results of this study can be applied to various drone applications, such as aerial photography, agriculture, or industry. Finally, in the future, other factors are expected to affect the differences in the number of blades regarding energy efficiency and flight duration.

The Influence of Liquid Components of GAP Propellant on Its Mechanical Properties

Abstract In response to the problem of poor mechanical properties of glycidyl azide polymer (GAP), a branched high molecular weight glycidyl azide polymer (B-GAP) was used as the adhesive to prepare a propellant with a solid component ratio of 78%. The effects of different network modifiers such as PL1, PL2, and PL3 on the mechanical properties of this type of propellant were studied. The results showed that the sample containing both PL1 and PL3 had the highest tensile strength at 0.712 MPa, but the elongation at break decreased to 35.7%; The sample containing only PL3 has the highest elongation at break, which is 73.3%, and the maximum tensile strength is only 0.315MPa. And the propellant containing PL1 has a lower loss factor; Next is PL3; The loss factor containing PL2 is relatively high.

Electrohydrodynamic Propeller as One of the Alternatives to Replace Conventional Propulsion Systems

In this article, an analysis of issues related to EHD propulsion systems, including their design and the working principle, is presented. The article deals with the advantages and shortcomings that influence their utilisation in the conditions of the Earth’s atmosphere. In the practical section of the article, a set of experiments aimed at elucidating a relationship between the geometry of the capacitor model applied voltage and the induced force is described. An essential task was to verify the functionality of a device and to quantify the efficiency of this type of propeller by applying experimental methods aimed at increasing the functionality.

Динаміка електрокерованих паливних клапанів реактивних двигунів малої тяги на «зеленому» паливі

Recently, the leading space countries have paid much attention to searching for and using new types of untoxic “green” propellants. Developments of 0.1 N to 220 N “green”-propellant thrusters have been reported, and some of them have been successfully tested in flight conditions. Liquid-propellant spacecraft thrusters are actuators of a spacecraft in-orbit motion control system. They are actuated from command signals of the spacecraft control system by applying a voltage to the electromagnet coils of the propellant valves of each of the engines that are to feed the propellant during a specified time interval to produce a required thrust impulse. A problem common to liquid-propellant thrusters irrespective of the propellant type is a thruster start-up delay with respect to the command signal and a thruster shut-down delay with respect to the electromagnet coil de-energizing. In other words, the thruster response is shifted with respect to the command signal. Because of this, the valve parameters must be chosen in such a way as to minimize the delay effect. The goal of this work is to determine design parameters of electrically controlled propellant valves that would provide an efficient in-orbit operation of “green”-propellant thrusters with a minimum of electric energy consumption. To determine these parameters, use was made of a branch standard, the procedure of work with which was based on empirical data and verified by numerical simulation. The key factor in shortening the thruster start-up delay is to reduce the seat-to-tip valve plate travel on condition that a required propellant amount is fed to the reaction chamber. However, this extends the shut-down delay, which has a harmful effect in the short-impulse operation mode. It is shown by calculation that after the electromagnetic parameters have reached their steady-state values, the voltage can be reduced by 30 to 40 per cent of its nominal value with the valve kept in an open state, after which the valve closes with a shorter delay. In addition, this way of valve energizing reduces the total electric energy consumption for valve operation. The mathematical model of valve dynamics allows one to determine the valve operation parameters in the case of short command signals probable in flight conditions. In such a case, a valve does not open to a full extent, which results in a low specific impulse. The results of this study may be used in the development of “green”-propellant thrusters.

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.

HYBRID DRONES WITH DUCTED AND ASYMMETRIC PROPELLERS: EXPERIMENTAL STUDIES AND APPLICATION PROSPECTS

This article presents a comprehensive analysis of hybrid unmanned aerial vehicles (UAVs) equipped with ducted and asymmetric propellers. The results of experimental studies confirm the advantages of using these types of propellers regarding aerodynamic efficiency, energy efficiency, noise reduction, and improved maneuverability. The possibility of combining asymmetric propellers with ducted designs, as well as their impact on thrust, flight stability, and other flight characteristics of drones, is examined in detail. Comparative tables and graphs of the results highlight key performance indicators. Particular attention is paid to the analysis of the application of drones with such propellers in urban conditions, and recommendations for further research and technology implementation are developed.

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.