Thrust Force Generation Research Articles

Comparative Assessment on Unsteady Aerodynamics of Thin and Thick Airfoils Subjected to Pitching Motion

This article presents the comparison between the unsteady flow characteristics of thick (t/c ≥ 6%) and thin (t/c ≤ 6%) airfoils performing pitching motion at Reynolds number Re = 3.6 × 10 5 . For the analysis, the considered airfoils are NACA 0012 as thick and symmetric airfoil and GOE 417A as thin and highly cambered airfoil. The analysis in this study is restricted to only two airfoils because from the preliminary investigations, similar aerodynamic characteristics with slight variation in their flow field development under same conditions were observed. The influence of reduced frequency, pitching amplitude and mean angle of attack on the airfoil’s aerodynamic performance in terms of instantaneous force coefficients is thoroughly investigated. Further, the flow surrounding the airfoils is also investigated. It is noticed that the aforementioned parameters substantially affect the instantaneous force coefficients (both qualitatively and quantitatively). Under certain conditions, the formation of reverse Karman vortex street was observed indicating airfoil’s thrust force generation. It must be noted that the conditions where the thrust force generation occurs for thick and symmetric airfoils like NACA 0012 are quite different from that of thin and cambered airfoils like GOE 417A. Additionally, a drastic change in the flow field around the airfoils is observed under similar conditions. For NACA 0012 airfoil, the formation and convection of the Leading Edge Vortex (LEV) under certain conditions has detrimental effects on its aerodynamic characteristics as it encourages early flow separation. However, the same cannot be true for thin and highly cambered airfoils like GOE 417A. Under the similar conditions with negligible variation, the LEV contributes toward providing extra suction over the GOE 417A airfoil’s suction side. This significantly improves airfoil’s aerodynamic characteristics.

Numerical modeling and parametric analysis of performance of a monopropellant thruster using a single-part catalyst bed model

Monopropellant hydrazine thruster, depending on their thrust level, specific impulse, and unique functional regime, are widely used in situation control, orbital transmission, and position correction systems of satellites. In these thrusters, hydrazine decomposes by passing through the catalyst bed in a highly exothermic reaction to hot gas products. Hot gases generate thrust force by passing through a convergent-divergent nozzle. Pore scale analysis of catalytic reactions is very common in various industries and is of interest to researchers due to its accuracy. In this paper, the decomposition chamber of a monopropellant hydrazine thruster is numerically simulated with a single-part bed model at the pore-scale. The length of decomposition chamber was 2.48 cm. Then the effects of parameters such as catalyst granule diameter, catalyst bed porosity coefficient and also chamber inlet pressure on the performance of the decomposition chamber and thruster are investigated. Simulations have been performed for catalyst granules with diameters of 0.88, 1.00 and 1.15 mm in three porosity coefficients of 0.4, 0.55 and 0.65. The inlet pressure is also changed from 10 to 25 bar in four different levels. The results showed that the porosity coefficient is the most effective parameter and with its decrease, the specific impulse and temperature rise, while the thrust force and mass flow rate intensify. Also, the size of the catalyst granules affects the performance of the bed and thruster so that by increasing it (at a certain porosity coefficient), a trend similar to the effect of decreasing the porosity coefficient can be seen in the results. On the other hand, with enhancing inlet pressure, the thrust force increases significantly. In this paper, the effect of bed parameters on the thruster performance is discussed in detail, which contains helpful results for researchers that work on improving the decomposition chamber efficiency.

Tombo Propeller: Bioinspired Deformable Structure Toward Collision-Accommodated Control for Drones

There is a growing need for vertical takeoff and landing vehicles, including drones, which are safe to use and can adapt to collisions. The risks of damage by collision, to humans, obstacles in the environment, and drones themselves, are significant. This has prompted a search into nature for a highly resilient structure that can inform a design of propellers to reduce those risks and enhance safety. Inspired by the flexibility and resilience of dragonfly wings, we propose a novel design for a biomimetic drone propeller called Tombo propeller. Here, we report on the design and fabrication process of this biomimetic propeller that can accommodate collisions and recover quickly, while maintaining sufficient thrust force to hover and fly. We describe the development of an aerodynamic model and experiments conducted to investigate performance characteristics for various configurations of the propeller morphology and related properties, such as generated thrust force, thrust force deviation, collision force, recovery time, lift-to-drag ratio, and noise. Finally, we design and showcase a control strategy for a drone equipped with Tombo propellers that collides in midair with an obstacle and recovers from collision continuing flying. The results show that the maximum collision force generated by the proposed Tombo propeller is less than two-thirds that of a traditional rigid propeller, which suggests the concrete possibility to employ deformable propellers for drones flying in a cluttered environment. This research can contribute to the morphological design of flying vehicles for agile and resilient performance.

Investigation Effect of Magnet Skew on Thrust Force in Linear Brushless Direct Current Motor with FEM

This study is concerned with the reduction of ripple in the thrust force produced in a linear Brushless Direct Current Motor (BLDC). To reduce the ripples in the generated thrust force, different methods such as structural solutions are applied both in the control part and in the production phase of the motor. In this study, skew application, which is one of the mechanical methods, is proposed. For this reason, the changes in the thrust force of a BLDC motor with a surface magnet-placed translator are investigated by applying different levels of skew to the magnets. First, a 3D solid model of the motor was created. A pole on the translator of the linear BLDC motor is composed of 3 equal magnet groups. For each skew level, the magnets were shifted 3 mm independently of each other and the thrust force values were examined. For this process, a 3D magnetostatic analysis of the linear BLDC motor was performed. The results obtained show that the skewing process applied to the magnets reduces the ripples in the thrust curve up to a certain point, after which no significant improvement in the ripple is observed, while the average force value decreases significantly.

Electromagnetic and experimental analyses of a low‐cost miniature tubular moving magnet linear oscillating actuator for miniature compressor applications

This article presents a miniature tubular moving magnet linear oscillating actuator (MT-MMLOA) that operates on an electro dynamic actuation mechanism. The proposed linear oscillating actuator comprises two main parts: the stator and the mover. In this topology, the stator assembly is composed of a modular C-core structure along with a separator to prevent flux cancelation, and the mover assembly accommodates axially magnetised permanent magnets (PMs) that contribute to high thrust force generation and present a less costly actuator compared to the conventional actuator design. The finite element analysis is performed and validated experimentally. Numerous linear oscillating actuator topologies proposed previously in the literature are compared with MT-MMLOA to analyse the electromagnetic performance. The results show that the motor constant, which is the performance parameter, is significantly increased from the conventional design. The PM volume is reduced, which is cost-effective. The overall volume of MT-MMLOA is also reduced due to reduction in the PM volume, which is advantageous for compactness. Consequently, the proposed MT-MMLOA is simple in structure, less costly, and easy to fabricate.

Effect of Drilling Penetration Angle on Delamination for One-Shot Drilling of Carbon Fiber Reinforced Plastic (CFRP)

Carbon-fibre-reinforced plastic is prominent with superb specific mechanical properties that contribute to its application in high technology industries, such as aircraft and automobiles' mechanical structures. These materials are considered hard to cut. The delamination issues frequently arise due to their anisotropy and inhomogeneity. In aircraft manufacturing, thousands of holes are required to assemble the structural parts. Hole perpendicularity issues undoubtedly might happen during manual drilling. The main purpose of this work is to study the effects of various minor slant drilling angles on thrust force generation and delamination by using a special drill reamer. From the investigation, the drilling penetration angle significantly impacted the delamination. The delamination factor for the entry and exit sides of holes relatively decreased from 1.042 and 1.087 to 1.027 and 1.049, respectively, as the thrust force declined from 114.8 N to 106.5 N from 5° to 0° drilling angle.

Unsteady aerodynamics of plunging cambered foil at low Reynolds number

The present work focuses on the investigation of unsteady aerodynamics of plunging cambered foil with conditions corresponding to that of a Micro Air Vehicle. The effect of non-dimensional plunge amplitude, plunging frequency and the dimensionless plunge velocity on the propulsive performance of a harmonically plunging cambered foil are studied by varying Reynolds number from 2.5 × 104 to 7.5 × 104. Further, the flow field around the foil is analysed to understand the influence of the above-mentioned parameters and the reasons behind the positive thrust force generation. It is observed that these investigated parameters remarkably influence the instantaneous force coefficients. It is also noticed that these parameters have a significant effect on the topology of the leading edge vortex which can dramatically change the aerodynamic performance of the foil. It is observed that the Reynolds number also has a significant influence on the drag-thrust transition.

Numerical Investigation of Flow Over Oscillating Cambered Foil at Low Reynolds Number

Abstract This paper aims to investigate the effect of pitching amplitude, mean angle of attack and frequency of oscillation on the propulsive characteristics of a harmonically oscillating cambered airfoil at Reynolds number of 5×104. The flow field around the foil is analyzed to study the influence of the above parameters and to understand the reasons behind the positive thrust force generation. It is observed that the instantaneous force coefficients of the airfoil vary both qualitatively and quantitatively with respect to change in the above-mentioned parameters. A transition of wake from Karman vortex to reverse Karman vortex is observed. It is also observed that the formation and convection of the leading edge vortex over the airfoil surface has a strong impact on the drag-thrust transition. It is also noticed that the change in the location of the pitching axis has a significant influence over thrust force generation and propulsion efficiency of the airfoil.

Measurement and evaluation of delamination factors and thrust force generation during drilling of multiwall carbon nanotube (MWCNT) modified polymer laminates

Measurement and evaluation of delamination factors and thrust force generation during drilling of multiwall carbon nanotube (MWCNT) modified polymer laminates

Anguilliform Swimming Performance of an Eel-Inspired Soft Robot.

In this article, we propose a soft eel robot design using soft pneumatic actuators that mimic eel muscles. Four pairs of soft actuators are used to construct the eel robot body. Pulse signals with suitable shifting phases are utilized to control delivery of compressed air to the actuators in sequence to create a sinusoidal wave from head to tail of the robot body. A model of hydrodynamic forces acting on an anguilliform swimmer when moving in fluid was built to estimate the thrust force generated by the robot at different tail beat frequencies. Experimental data revealed that the generated thrust force was positively correlated with the beat frequency. Measured data showed that swimming efficiency depended on both generated thrust force and body posture in situ. At the beat frequency of 1.25 Hz, and air pressure at three segments from head to tail of 65, 50, and 30 kPa, respectively, the eel robot body showed the best cost of transport (COT) of 19.21 with velocity of 10.5 cm/s (or 0.198 body length per second [BL/s]), compared to the other's values of operation frequency and air pressure. We also found that control shifting phase strongly affects the swimming speed and COT. The robot body reached the highest velocity at around 19 cm/s (0.36 BL/s) with the COT of 10.72. Obtained result in this research would contribute to development of soft elongated swimming robot and enhance the knowledge on swimming performance of both robot and natural eels.

Generation of Thrust Force in High Density and Low Temperature Plasma by Neutral Entrainment

The main objective of this article is to discuss the concept of a device that uses dense low temperature atmospheric plasma to generate thrust to enable vertical take-off and landing. Plasma consisting of atmospheric gases and potassium admixture have been enclosed in a toroidal chamber with the help of a magnetic field ( $B$ ) and a radial electric field ( $E$ ) placed perpendicular to it. The electric field induces the parallel current ( $j_{II} $ ) and drives the $E\times B$ drift in azimuthal direction, which in partially ionized and weakly magnetized plasma induces the Hall current ( $j_{\wedge } $ ). The Hall current induces the $B_{p} $ paramagnetic field with an intensity up to 5.5 T, and the parallel current induces the azimuthal field ${B}''_{\Phi } $ with an intensity up to 4 T. Ohmic heating controlled by these two currents raises the plasma temperature from 0.44 eV (injection temperature) to 1.38 eV (which is the upper value resulting from the emergence of electrothermal instability). Neutrals injected into the toroidal chamber are heated by charge exchange collisions (CEXs), then they are released through a cylindrical nozzle generating the thrust force ( $F_{T} $ ) of $\sim 2.91\cdot 10^{5} \textrm {N}$ at a temperature of ~ 1 eV. Power consumption at this thrust level attains $\sim 1.32\cdot 10^{9} \textrm {W}$ and can be covered by remote microwave or laser power sources.

Effect of Cutting Parameters and Tool Geometry on the Performance Analysis of One-Shot Drilling Process of AA2024-T3

Drilling is an important machining process in various manufacturing industries. High-quality holes are possible with the proper selection of tools and cutting parameters. This study investigates the effect of spindle speed, feed rate, and drill diameter on the generated thrust force, the formation of chips, post-machining tool condition, and hole quality. The hole surface defects and the top and bottom edge conditions were also investigated using scan electron microscopy. The drilling tests were carried out on AA2024-T3 alloy under a dry drilling environment using 6 and 10 mm uncoated carbide tools. Analysis of Variance was employed to further evaluate the influence of the input parameters on the analysed outputs. The results show that the thrust force was highly influenced by feed rate and drill size. The high spindle speed resulted in higher surface roughness, while the increase in the feed rate produced more burrs around the edges of the holes. Additionally, the burrs formed at the exit side of holes were larger than those formed at the entry side. The high drill size resulted in greater chip thickness and an increased built-up edge on the cutting tools.

Estimation of the thrust coefficient of a Quadcopter Propeller using Computational Fluid Dynamics

A Quadcopter is a mechatronics device with complex dynamics, because six degree of motion is control by four thrust forces. These thrust force are generated by propellers rotation, driven by DC motors. The main objective of present study is to perform the flow analysis on a Quadcopter propeller, to find out the propeller thrust coefficient (Kt). The flow analysis of Quadcopter propeller is essential as it opposes the gravitational and aerodynamic forces due to the drag and weight mounted on it. So, a 3D CAD model of Quadcopter propeller was designed in Catia and imported to Ansys fluid flow (fluent) module for fluid flow simulation. The flow over propeller was simulated under different angular speed with k-epsilon turbulence model. The obtained results conclude that the designed propeller can generate the required amount of thrust force to lift additional payloads. Furthermore the generated thrust force at different angular speed was used to find out the thrust coefficient. This thrust coefficient will used in developing the mathematical dynamic model of Quadcopter UAV.

Experimental analysis and parametric optimization of drilling process for ferrous clay composite using GRA-PCA approach

The use of materials mixture with non-metallic ingredients composed by powder metallurgy (PM) are getting increased attention in many industries. The newly developed composite material is mainly applied to the structural parts in the many industries. PM parts machining is still a challenge and known as difficult-to-cut metals for manufacturers because of the many factors mainly porosity, Nano particles and complex microstructure. In this work, the mechanical properties like density and porosity along with the machinability in drilling of a newly developed sintered powder metallurgy (P/M) components having Nano-particles of bentonite clay as machinability enhancer is evaluated by a standard twist drill. The impact of this paper aims to reveal the key cutting phenomena i.e. generation of thrust forces, quality of surface roughness, and new insight into the machining mechanism of sintered material. The parameters involved in the machinability study are as speed, feed rate and Nano-particles of bentonite clay for controlling the parametric variables on the response parameters. The speed has the major (95%) effect on the thrust force where the clay percentage has the major (84%) effect on the surface roughness. The less thrust force and low surface roughness have been achieved at 5% clay with 910 rpm and 1% clay with 2265 rpm, respectively. Further, the hybrid grey relational analysis along with principal component analysis (GRA-PCA) has been carried out to find the optimum condition. The less thrust force (Ft) and low surface roughness (Ra) has been found at 1% clay and 910 rpm. The confirmation of optimal process parameters has been made with overall evaluation criteria (OEC) and found the same optimum condition. The X-ray diffraction despises homogeneous mixture of clay in ferrous clay composite. The SEM analysis exposed the presence of clay particles and plastically deformed area during drilling of ferrous clay composite. Thus, this analysis show that the 1% of Nano-particles of bentonite clay is helpful as porosity fillers or machinability enhancer at low speed and within acceptable mechanical properties.

Effects of St and Re on propulsive performance of bionic oscillating caudal fin

Many fishes show an excellent swimming ability by agilely oscillating their fins, and the caudal fin is a main organ for a fish to propel itself. This propulsion mode provides inspiration to the design of biomimetic underwater vehicles. On this basis, we take an oscillating fin as our study subject and build a computational fluid dynamic model by mimicking the lunate caudal fin of tuna. Numerical simulations are performed to evaluate the effects of the Strouhal number (St) and Reynold number (Re) on the wake structure and hydrodynamic performance of the oscillating caudal fin. Navier-Stokes equations are used to solve the unsteady flow for the oscillating caudal fin, as well as the user-defined-function and dynamic mesh methods are applied to realize and track the instant locomotion, respectively. Then the validity and reliability of the numerical method are verified by experiments and convergence tests. Results show that the fish can obtain a larger instantaneous thrust force when the caudal fin flaps under a higher St but when its propulsive efficiency is mediocre or even worsens. This situation usually occurs during the escape or hunting actions of fish. Meanwhile, being in a turbulence flow, which corresponds to a larger Re, is helpful for the caudal fin to obtain a relatively higher thrust force and propulsive efficiency. Specially, a detailed analysis on the connection between the wake vortex topology, kinematics and force generation of the caudal fin is performed. Results suggests that the wake is dominated by one or two sets of complex vortex rings which convect at different oblique angles to the wake flow centerline. With various Re and St, the hydrodynamic performances of the caudal fin strongly depend on the flow dynamics underlying the force production, including the orientation, interconnection and dissipation rate of the vortex rings. Such as jet flows inducted by these vortex rings, play a critical role in the thrust force generation for an oscillating caudal fin.

Optimization of thrust force in drilling of carbon-basalt hybrid composites through Taguchi and RSM

The main object of the present work is to obtain better quality holes during drilling operation. Carbon-Basalt hybrid composite is a better performing composite with lesser price. For the present work, the hybrid composite test specimen was prepared by hand layup method. General purpose polyester resin is used as the matrix material. During the manufacturing process, alternate layers of carbon and basalt are stacked to prepare the composite. The maintained weight fraction of the fiber is 50%. The thickness of the obtained composite specimen is 6 mm. Delamination is the major reason for the rejection of drilled composites. The magnitude of delamination is directly proportional to the thrust force generated during drilling. Hence in the present work, an attempt has been made to reduce the thrust force to minimize the damage by optimizing the machining variables using Taguchi and RSM methods. The experiments were designed by DOE method. Taguchi’s 3 levels and 3 factors array was used to get the combination of parameters for each experiments. Totally 27 holes are drilled with different combinations of process parameters. The considered process parameters and their levels are: Drill diameter (6 mm, 8 mm & 10 mm), feed rate (50 mm/min, 75 mm/min & 100 mm/min) and spindle speed (750 rpm, 1000 rpm & 1250 rpm). Drilling process was carried out on a high precision CNC machine using HSS drill bits. The thrust force was measured by a Kistler dynamometer. Using ANOVA, the significant effect of considered parameters on the generated thrust force was also predicted. The result reveals that, the parameter feed rate has the most significant effect on thrust force, which is followed by the drill diameter. The least significant parameter is spindle speed. Both Taguchi and RSM methods suggest that, DD1, F1 and S3 combination parameters yields the lowest thrust value.

Experimental investigation of biomimetic propulsion through a scaled up branched flagellated artificial nanoswimmer

ABSTRACT Locomotion of bacteria in fluid at small scale is accomplished by cilia and flagella present on its surface. In the present study, existence of cilia on Paramecium surface is mimicked to design scaled-up swimmer rather than utilising its biological function. In the present study, the branches (cilia) on flagella (Paramecium) is employed for designing of tail of an artificial nanoswimmer and experiments are performed at scaled-up level in silicon oil medium to maintain low Reynolds number. The effects of branches on generation of thrust force are investigated by fabricating the branched flagella using flexible polydimethylsiloxane biocompatible material suitable for human body and biological applications. The resulting data are quantitatively compared through statistical analysis. In the present research work, various designs of branched flagellated swimmer are fabricated by varying the number of branches and spacing between branches. Enhancement in thrust force is observed approximately 24% when number of branches is increased from 8 to 28. Therefore, it is concluded that branches on flagella play significant role in enhancement of thrust force for propelling nanoswimmer. Spacing between 8 branches flagella is also varied from 5 to 15 mm and percentage increase in thrust force is observed as 8.1%.

New Technique of Applying Ultrasonic Frequency on Drilling Chemical Treated Glass

The usage of chemical treated toughened glass has steadily increased especially for electronic panel display devices. Due to the ion-exchange process throughout the surface treatment phase has create six to eight times tougher and crack resistance as compare to normal float glass. Owing to these, the subsequent manufacturing process such as conventional drilling is almost impossible for this toughened glass. Considering these fact, in this paper feasibility study on the effectiveness of applying ultrasonic frequency during the drilling process toward holes’ quality were investigated. Sets of experimental investigation of ultrasonic assisted drilling with varying speed and feed rate were performed to evaluate the burr formation and the generated thrust force magnitude. From the experimental results, it was found that the areas of burr formation and the thrust force magnitude were dependent with the drilling parameter. It also can be noted that the present of the ultrasonic vibration show significant improvement on the holes’ performance. By incorporating the drilling process with an ultrasonic vibration able to decreases the magnitude of thrust force and increases the effectiveness of chip evacuation process due to the intermittent cutting process. The outcome from this work serve as a basis for advancing the technology related to micro machining of chemical treated toughened glass.

Monitoring of hole surface integrity in drilling of bi-directional woven carbon fiber reinforced plastic composites

Fiber-reinforced plastic is one of the top priorities lightweight materials with excellent mechanical properties for the aerospace industries in recent years. However, it is difficult to machine despite having unique properties due to its non-homogeneous and abrasive nature in alternate fiber and matrix layers. Thus, it is found to be a challenging task to drill hole on such hard-to-machine materials, which is highly essential for the development of most of the engineering structural components. The present work addresses various drilling-induced defects such as delamination, circularity error, and roughness variations in the hole surface during drilling of quasi-isotropic cross-fiber oriented bi-directional woven-type carbon fiber reinforced plastic laminate using a full factorial design of experiments for different drill geometry. The response surface methodology was considered for the regression model development, which was found to be highly significant. The machining forces with associated torque have also been acquired during drilling, which was divided and further analyzed in time domain to correlate with drilling flaws. The drilling-induced delamination was found to be higher at a high feed rate using a higher drill point angle due to substantial thrust force generation at the initial stages in the drilling cycle. However, the internal surface finish with associated circularity error was reduced for higher spindle speed with less feed rate using a low drill point angle because of low torque fluctuation at the final drilling phases. The axial thrust force was found to be a prime indicator of drilled hole surface delamination, whereas drilling torque precisely indicated internal surface roughness as well as circularity error. The global root mean square, along with a local peak of thrust and torque, both were highly essential to completely characterize the drilled hole quality.

FEM based mathematical modelling of thrust force during drilling of Al7075-T6

Like most machining processes, drilling is affected by many parameters such as the tool diameter, the cutting speed and feed. The current research investigates the possibility of developing a finite element modelling based prediction model for the generated thrust force during drilling of Al7075-T6 with solid carbide tools. A total of 27 drilling experiments were carried out in order to examine the interaction between three key parameters and their effect on thrust force. In addition, simulations of the experiments were realized with the use of DEFORM3D™ software in order to obtain the necessary numerical data. Finally, a comparison was made between the experimental and the numerical results to verify that reliable modelling is feasible. The mathematical model was acquired with the use of response surface methodology and the verification of the adequacy of the model was performed through an analysis of variance. The majority of the simulations yielded results in agreement with the experimental results at around 95% and the derived model offered an accuracy of 5.9%.