scholarly journals Optimization of the trimming tilting angle of the electric tiltrotor propeller group

2021 ◽  
Vol 24 (4) ◽  
pp. 50-60
Author(s):  
V. I. Busurin ◽  
P. V. Mulin
Keyword(s):  
Lift Coefficient ◽  
Steady Motion ◽  
Aerodynamic Characteristics ◽  
Total Power ◽  
Flight Mode ◽  
Tilting Angle ◽  
Efficient Performance ◽  
Thrust Vector ◽  
Total Thrust ◽  
The One

The paper examined the possibility of improving the energy efficient performance of an electric tiltrotor with a lift-propulsion propeller group for a steady flight mode by reducing the energy consumption of the propeller group per unit of time or per unit of the path traveled by the electric tiltrotor. This is achieved by selecting the optimal tilting angles of the electric tiltrotor total thrust vector. In the proposed approach, the trimming tilting angle of the propeller group is variable, depending on the aerodynamic characteristics of the electric tiltrotor, its propeller group. Since the propeller group is equipped with the drives for tilting them, this approach is easily implemented by the conventional facilities of the electric tiltrotor. The tilting of the total thrust vector, on the one hand, leads to an increase in the effective value of the aerodynamic lift coefficient and, on the other hand, it is accompanied by a decrease in the projection of the total thrust vector on the flight speed vector, a change in the drag and power required to create the thrust of the propeller group. This circumstance makes it necessary to solve the optimization problem in order to increase the maximum endurance and long-range capabilities in the cruise mode of the electric tiltrotor flight. The paper presents a method for calculating the optimal tilting angles of the total thrust vector based on the equations of steady motion of the electric tiltrotor in the cruise flight mode, the expression for the total power required for the rotation of the propellers of the propeller group. The analytical dependences for the optimal tilting angles of the total thrust vector are obtained depending on the ratio of the wing area to the total propeller-disk area of the propeller group and the aerodynamic quality of the electric tiltrotor.

scholarly journals Features of flow around transport aircraft model with running propellers by modelled engine failure in wind tunnel

2021 ◽  
Vol 2103 (1) ◽  
pp. 012206
Author(s):  
V I Chernousov ◽  
A A Krutov ◽  
E A Pigusov
Keyword(s):  
Wind Tunnel ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Light Transport ◽  
Transport Aircraft ◽  
Engine Failure ◽  
The One ◽  
Low Speed Wind Tunnel ◽  
Control Surfaces ◽  
Landing Mode

Abstract This paper presents the experiment results of modelling the one engine failure at the landing mode on a model of a light transport airplane in the T-102 TsAGI low speed wind tunnel. The effect of starboard and port engines failure on the aerodynamic characteristics and stability of the model is researched. The model maximum lift coefficient is reduced about ≈8% and there are the same moments in roll and yaw for starboard and port engines failure case. It was found that the failure of any engine has little impact on the efficiency of control surfaces. Approaches of compensation of forces and moments arising in the engine failure case were investigated.

Flow analysis on the ventral gap of a paper airplane

2020 ◽  
pp. 095440622094607
Author(s):  
Min Chang ◽  
Xiaoyu Feng ◽  
Yang Zhang ◽  
Xu Zhang ◽  
Junqiang Bai
Keyword(s):  
Delta Wing ◽  
Lift Coefficient ◽  
Flow Analysis ◽  
Aerodynamic Characteristics ◽  
Micro Aerial Vehicle ◽  
Moment Coefficient ◽  
Aerial Vehicle ◽  
Paper Airplane ◽  
The One ◽  
Flow Vortex

It is a challenging work to design micro aerial vehicle with great aerodynamic performance because the tiny wingspan at low-Reynolds-number cannot provide lift efficiently. The aerodynamic configuration of a classic delta-wing paper airplane is investigated in the present work with numerical method to discover its potential for micro aerial vehicle designs. Furthermore, the effect of the ventral gap on the aerodynamic characteristics of the paper airplane is investigated herein. The stall angles of attack reach 37.5° and 40°, respectively, for ventral opened configuration and the closed one, and the maximum lift coefficient reaches 1.49 and 1.46. The ventral-opened configuration has negative pitching moment coefficient (−0.01431) even at 37.5° while the closed one has a positive coefficient (0.01402). The reason may be the gap leads to a strong back-flow vortex before the trailing edge in the ventral gap which produces a strong nose-down moment. Generally, the ventral gap improves lift and dramatically influences the longitudinal stability compared with the one without it.

Design and simulation research of the double-spin folding mechanism based on a suspended missile

2021 ◽  
pp. 154851292110231
Author(s):  
ZH Yuan ◽  
SY Guo ◽  
SN Zhang ◽  
JQ Zhao ◽  
WJ Lu ◽  
...  
Keyword(s):  
High Reliability ◽  
Lift Coefficient ◽  
Great Influence ◽  
Reference Value ◽  
Aerodynamic Characteristics ◽  
Simulation Software ◽  
Fluid Simulation ◽  
Simulation Research ◽  
Double Spin ◽  
Locking Mechanism

Based on the suspension of a missile using folding rotary wings and airbags, in order to improve the basic parameters and motion characteristics of the rotor during the unfolding process and analyze the aerodynamic characteristics of the entire device in the suspension state, after proposing a scheme of double-spin mechanism, the main folding and unfolding mechanism, initial driving device, rotating driving device, and locking mechanism were designed, and the simulation research is studied by the Automatic Dynamic Analysis of Mechanical System and Ansys Fluent Fluid Simulation software, respectively. The results show that the rotation rate was controlled at 41.8 mm/s, the various motion parameters are reasonable, and the operation process is relatively smooth, with high reliability. The speed and pressure value at the tip of the rotor are higher and the aerodynamic disturbance is obvious, which has a great influence on the aerodynamic performance. The speed and pressure distribution of the surrounding flow field is stable, the lift provided is 46 N, and the lift coefficient is 0.55, which can ensure the long-time suspension state of the missile. This paper puts forward a valuable design idea and has practical reference value for the research of the suspended missile.

Numerical study of the aerodynamic and power characteristics of the cycloidal rotor, under incoming flow

2019 ◽  
pp. 25-34
Author(s):  
Александр Анатольевич Дектерев ◽  
Артем Александрович Дектерев ◽  
Юрий Николаевич Горюнов
Keyword(s):  
Flow Velocity ◽  
Numerical Study ◽  
Lift Coefficient ◽  
Simulation Method ◽  
Aerodynamic Characteristics ◽  
Incoming Flow ◽  
Ansys Fluent ◽  
Energy Characteristics ◽  
Power Characteristics ◽  
Calculation Results

Исследование направлено на разработку и апробацию методики численного моделирования аэродинамических и энергетических характеристик циклоидального ротора. За основу взята конфигурация ротора IAT21 L3. Для нее с использованием CFD-пакета ANSYS Fluent построена математическая модель и выполнен расчет. Проанализировано влияние скорости набегающего потока воздуха на движущийся ротор. Математическая модель и полученные результаты исследования могут быть использованы при создании летательных аппаратов с движителями роторного типа. This article addresses the study of the aerodynamic and energy characteristics of a cycloidal rotor subject to the influence of the incoming flow. Cycloidal rotor is one of the perspective devices that provide movement of aircrafts. Despite the fact that the concept of a cycloidal rotor arose in the early twentieth century, the model of a full-scale aircraft has not been yet realized. Foreign scientists have developed models of aircraft ranging in weight from 0.06 to 100 kg. The method of numerical calculation of the cycloidal rotor from the article [1] is considered and realized in this study. The purpose of study was the development and testing of a numerical simulation method for the cycloidal rotor and study aerodynamic and energy characteristics of the rotor in the hovering mode and under the influence of the oncoming flow. The aerodynamic and energy characteristics of the cycloidal rotor, rotating at a speed of 1000 rpm with incoming flow on it with velocities of 20-80 km/h, were calculated. The calculation results showed a directly proportional increase of thrust with an increase of the incoming on the rotor flow velocity, but the power consumed by the rotor was also increased. Increase of the incoming flow velocity leads to the proportional increasing of the lift coefficient and the coefficient of drag. Up to a speed of 80 km/h, an increase in thrust and power is observed; at higher speeds, there is a predominance of nonstationary effects and difficulties in estimating the aerodynamic characteristics of the rotor. In the future, it is planned to consider the 3D formulation of the problem combined with possibility of the flow coming from other sides.

Lift Control Using MEMS-Based Moving Trailing-Edge Tabs

2002 ◽  
Author(s):  
C. P. van Dam ◽  
C. Bauer ◽  
D. T. Yen Nakafuji
Keyword(s):  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Trailing Edge ◽  
Aircraft Wings ◽  
Lifting Surface ◽  
Lifting Surfaces ◽  
Lift Control

Micro-electro-mechanical (MEM) translational tabs are introduced for active lift control on aircraft. These tabs are mounted near the trailing edge of lifting surfaces such as aircraft wings and tails, deploy approximately normal to the surface, and have a maximum deployment height on the order of one percent of the section chord. Deployment of the tab effectively changes the sectional camber, thereby changing the aerodynamic characteristics of a lifting surface. Tabs with said deployment height generate a change in the section lift coefficient of approximately ±0.3. The microtab design and the techniques used to fabricate and test the tabs are presented.

A Simple and Robust Subsonic Boundary Layer Method to Be Used with the Panel Method for Wing Calculations Using a Wing Strip Approach

2015 ◽  
Vol 798 ◽  
pp. 596-601
Author(s):  
R.F. Francisco Reis ◽  
Guilherme A. Santana ◽  
Paulo Iscold ◽  
Carlos A. Cimini
Keyword(s):  
Boundary Layer ◽  
Lift Coefficient ◽  
Aircraft Design ◽  
Aerodynamic Characteristics ◽  
Viscous Drag ◽  
Layer Method ◽  
Boundary Layer Method ◽  
Dimensional Boundary ◽  
Classical Integral ◽  
Empirical Corrections

This paper will present the development of a simple subsonic boundary layer method suitable to be used coupled with panel methods in order to estimate the aerodynamic characteristics, including viscous drag and maximum lift coefficient, of 3D wings. The proposed method does not require viscous-inviscid iterations and is based on classical integral bi-dimensional boundary layer theory using Thwaites and Head ́s models with bi-dimensional empirical corrections applied to each wing strip being therefor robust and efficient to be used in the early conceptual stage of aircraft design. Presented results are compared to the Modified CS Method in an IBL scheme and experimental data and are shown to provide good results.

scholarly journals Aerodynamic and Vibration Characteristics of the Micro-Octocopter at Low Reynolds Number

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Xiaohua Zou ◽  
Mingsheng Ling ◽  
Wenzheng Zhai
Keyword(s):  
Reynolds Number ◽  
Load Capacity ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Aerodynamic Characteristics ◽  
Vibration Characteristics ◽  
Low Reynolds ◽  
Vibration Performance ◽  
Drag Ratio ◽  
Lift To Drag Ratio

With the development of flight technology, the need for stable aerodynamic and vibration performance of the aircraft in the civil and military fields has gradually increased. In this case, the requirements for aerodynamic and vibration characteristics of the aircraft have also been strengthened. The existing four-rotor aircraft carries limited airborne equipment and payload, while the current eight-rotor aircraft adopts a plane layout. The size of the propeller is generally fixed, including the load capacity. The upper and lower tower layout analyzed in this paper can effectively solve the problems of insufficient four-axis load and unstable aerodynamic and vibration performance of the existing eight-axis aircraft. This paper takes the miniature octorotor as the research object and studies the aerodynamic characteristics of the miniature octorotor at different low Reynolds numbers, different air pressures and thicknesses, and the lift coefficient and lift-to-drag ratio, as well as the vibration under different elastic moduli and air pressure characteristics. The research algorithm adopted in this paper is the numerical method of fluid-solid cohesion and the control equation of flow field analysis. The research results show that, with the increase in the Reynolds number within a certain range, the aerodynamic characteristics of the miniature octorotor gradually become better. When the elastic modulus is 2.5 E, the aircraft’s specific performance is that the lift increases, the critical angle of attack increases, the drag decreases, the lift-to-drag ratio increases significantly, and the angle of attack decreases. However, the transition position of the flow around the airfoil surface is getting closer to the leading edge, and its state is more likely to transition from laminar flow to turbulent flow. When the unidirectional carbon fiber-reinforced thickness is 0.2 mm and the thin arc-shaped airfoil with the convex structure has a uniform thickness of 2.5% and a uniform curvature of 4.5%, the aerodynamic and vibration characteristics of the octorotor aircraft are most beneficial to flight.

Computational Analysis of Airfoil Merging and its Effect on Performance of Lift Based Vertical Axis Wind Turbine

2016 ◽  
Author(s):  
Akshay Basavaraj
Keyword(s):  
Reynolds Number ◽  
Wind Turbine ◽  
Lift Coefficient ◽  
Turbine Blades ◽  
Vertical Axis ◽  
Aerodynamic Characteristics ◽  
Vertical Axis Wind Turbine ◽  
Low Wind Speed ◽  
Naca 0012 ◽  
Selection Of

In regions of low wind speed, overcoming the starting torque of a Vertical Axis Wind Turbine (VAWT) becomes a challenge aspect. In order to overcome this adversity, careful selection of airfoils for the turbine blades becomes a priority. This paper tries to address the issue utilizing an approach wherein by observing the effect of merging two airfoils. Two airfoils which are of varying camber and thickness are merged and their aerodynamic characteristics are evaluated using the software XFOIL 6.96. For a variation in angle of attack from 0 to 90°, aerodynamic analysis is done in order to observe the behavior of one quarter of the entire VAWT cycle. An objective function is developed so as to observe the maximum possible torque generated by these airfoils at Reynolds number varying from 15,000–120,000. Due to change in the value of CL observed at Low Reynolds Number using commercial CFD softwares, multiple objective functions are utilized to observe the behavior over a range of Reynolds number. An experimental co-relation between the cut-in velocity and the lift-coefficient of the airfoils is developed in order to predict the cut-in velocity of the interpolated airfoils. The airfoils used for this paper are NACA 0012, NACA 0018, FX 66 S196, Clark Y (smooth), PT 40, SD 7032, A 18, SD 7080, SG 6043 and SG 6040.

An Experimental Methodology to Determine Components of Power Losses of a Gearbox

2021 ◽  
Vol 143 (11) ◽  
Author(s):  
A. Dindar ◽  
K. Chaudhury ◽  
I. Hong ◽  
A. Kahraman ◽  
C. Wink
Keyword(s):  
Power Loss ◽  
Spur Gear ◽  
Rolling Element Bearing ◽  
Experimental Methodology ◽  
Total Power ◽  
Gear Pair ◽  
Rolling Element Bearings ◽  
Power Losses ◽  
Rolling Element ◽  
The One

Abstract In this study, an experimental methodology is presented to separate various components of the power loss of a gearbox. The methodology relies on two separate measurements. One is designed to measure total power loss of a gearbox housing a single spur gear pair under both loaded and unloaded conditions such that load-independent (spin) and load-dependent (mechanical) components can be separated. With the assumption that gear pair and rolling element bearings constitute the bulk of the gearbox power loss, a second measurement system designed to quantify rolling element bearing losses is proposed. With this setup, spin and mechanical power losses of rolling element bearings used in the gearbox experiments are measured. Combining the sets of gearbox and bearing data, power loss components attributable to the gear pair and rolling element bearings are quantified as a function of speed and torque. The results indicate that all gear and bearing related components are significant and a methodology such as the one proposed in this study is warranted.

Aerodynamics of Gliding Flight in a Falcon and Other Birds

1970 ◽  
Vol 52 (2) ◽  
pp. 345-367 ◽  
Author(s):  
VANCE A. TUCKER ◽  
G. CHRISTIAN PARROTT
Keyword(s):  
Wind Tunnel ◽  
High Performance ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Wing Span ◽  
Technical Errors ◽  
Gliding Flight ◽  
Air Speed ◽  
D Values ◽  
D Value

1. A live laggar falcon (Falco jugger) glided in a wind tunnel at speeds between 6.6 and 15.9 m./sec. The bird had a maximum lift to drag ratio (L/D) of 10 at a speed of 12.5 m./sec. As the falcon increased its air speed at a given glide angle, it reduced its wing span, wing area and lift coefficient. 2. A model aircraft with about the same wingspan as the falcon had a maximum L/D value of 10. 3. Published measurements of the aerodynamic characteristics of gliding birds are summarized by presenting them in a diagram showing air speed, sinking speed and L/D values. Data for a high-performance sailplane are included. The soaring birds had maximum L/D values near 10, or about one quarter that of the sailplane. The birds glided more slowly than the sailplane and had about the same sinking speed. 4. The ‘equivalent parasite area’ method used by aircraft designers to estimate parasite drag was modified for use with gliding birds, and empirical data are presented to provide a means of predicting the gliding performance of a bird in the absence of wind-tunnel tests. 5. The birds in this study had conventional values for parasite drag. Technical errors seem responsible for published claims of unusually low parasite drag values in a vulture. 6. The falcon adjusted its wing span in flight to achieve nearly the maximum possible L/D value over its range of gliding speeds. 7. The maximum terminal speed of the falcon in a vertical dive is estimated to be 100 m./sec.

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