Ducted Fan Research Articles

Development and testing of vertical take-off and landing aerial vehicle with tandem electric ducted fan motor

Development and testing of vertical take-off and landing aerial vehicle with tandem electric ducted fan motor

Development of Dual-Unit Ceiling Adhesion Robot System With Passive Hinge for Obstacle Traversal Under Kinodynamic Constraints

The inspection of high ceilings or surfaces is important to ensure the quality and safety of infrastructure; however, the approach adopted by people or conventional robots is rather limited. Kinodynamic constraints (simultaneous kinematic and dynamic constraints) are presented by obstacles in real-life scenarios, such as suspended piping and wiring, which further limits the usability of robots. Therefore, this paper proposed an adhesion robot system that is attached to and maneuvers on flat and curved ceilings while traversing obstructions. To traverse obstacles, the robot comprises two units connected by a passive hinge mechanism. Traversal motion is achieved under adhesion force control with preexisting electric ducted fans without using separate hinge motors; thus, no additional weight is included. In addition to robot hardware, this study investigated the development of a control method based on dynamic analysis under the aforementioned kinodynamic constraints. Specifically, the proposed control algorithm considers the slipping and rollover conditions of the robot caused by the external force and moment applied to the unit during the obstacle traversal, respectively. The algorithm was systematically analyzed by conducting simulations to prevent the robot from experiencing adhesion failure, and the results were verified experimentally. The use of the robot in real-life scenarios was determined by performing feasibility tests in real-life applications.

Aerodynamic Design of Cooling Guide for Electrical Machine in Electric Ducted Fan

Abstract Electric ducted fan has newly emerged as the most compact type of propulsion fan for flying cars, because of its flexible configuration arrangement, low noise level and high safety level operation. Typically, an electric ducted fan is composed of a hub-driven fan and a hub-mounted inner rotor electrical machine. The thermal management of the hub-mounted electrical machine is essential because it determines the machine's continuous output power and reliability, as well as the fan thrust force. The heat transmitted from the stator winding to the cooling guide vane (CGV) is dissipated by introducing the air flow at hub region to the CGV. Therefore, in order to better improve the thermal performance of the CGV, an aerodynamic design of CGV is proposed in this paper for better thermal management of stator end-windings. First, for a certain desired power output of electrical machine under temperature constraints of stator winding, lumped thermal network is established to derive the requirement of heat transfer coefficients of the CGV. Then, from engineering feasibility, three different CGVs including straight type, arc-shape type and airfoil-shape type are tested by computational fluid dynamics. The evaluation of the CGV designs include the flow characteristics, power requirements, and thermal characteristics for stator winding cooling purposes. In comparison with the conventionally straight type CGV, improvements are gained from the designed arc-shape type and airfoil-shape type cooling configurations, whereas the fan thrust force remains the same simultaneously. It is verified that the arc-shape type and airfoil-shape type CGVs are promising in enhancing the thermal management performance of the electrical machine stator winding without power requirement.

Model Predictive Control Technique for Ducted Fan Aerial Vehicles Using Physics-Informed Machine Learning

This paper proposes a model predictive control (MPC) approach for ducted fan aerial robots using physics-informed machine learning (ML), where the task is to fully exploit the capabilities of the predictive control design with an accurate dynamic model by means of a hybrid modeling technique. For this purpose, an indigenously developed ducted fan miniature aerial vehicle with adequate flying capabilities is used. The physics-informed dynamical model is derived offline by considering the forces and moments acting on the platform. On the basis of the physics-informed model, a data-driven ML approach called adaptive sparse identification of nonlinear dynamics is utilized for model identification, estimation, and correction online. Thereafter, an MPC-based optimization problem is computed by updating the physics-informed states with the physics-informed ML model at each step, yielding an effective control performance. Closed-loop stability and recursive feasibility are ensured under sufficient conditions. Finally, a simulation study is conducted to concisely corroborate the efficacy of the presented framework.

Modeling and simulation of one- and two-row six-bladed ducted fans

The problem of simulation of efficient ducted fan type propulsors is considered. From experience of operation of twin blades in fantails of helicopters, it is known that this configuration creates less noise compared to a uniform arrangement of the blades around the circumference. However, the flow behind such fan is less uniform than that of a conventional ducted fan. For multicopter-type unmanned aircraft and air taxis, the key problem is flight in take-off and landing modes as well as acoustic and vortex fields created by propulsors in these modes. The decrease in the noise level in propellers with twin blades can potentially be accompanied by an increase in non-stationary vortex effects on the aircraft as well as a decrease in specific thrust. The objectives were to develop a method for simulation of ducted fan propellers in the takeoff and landing mode, to determine the optimal angle between the blades, and to compare a ducted fan with twin X-shaped blades to conventional blade position. Turbulent flows were calculated using transient Reynold-averaged Navier-Stokes equations, complemented by SST turbulence model, and large eddy simulation with WALE subgrid viscosity model. The calculations used the modification γ–Reθ Transition SST of the Langtry-Menter turbulence model, where there are relations for the intermittency criterion, which made it possible to consider the laminar-turbulent transition and the appearance of thin laminar separation bubbles that affect both the thrust of the propeller and the non-uniformity of the flow behind it. Testing was carried out on four-bladed propellers according to the known results of the TsAGI reference experiments. Testing of the γ–Reθ Transition SST Langtry-Menter turbulence model showed that it reproduces the dependence of the thrust coefficient and power factor on the blade angle better than the standard SST model. Calculations have shown that there is a clearly defined optimum angle between the paired blades. A comparison of three-bladed, six-bladed single and six-bladed propellers with twin blades showed that the latter option has slightly better thrust characteristics and creates a significantly lower noise level on the ground. The studied characteristics of ducted fans demonstrate the prospects for the use of propellers with twin blades in aircraft with vertical takeoff and landing. The developed numerical method can be directly used for industrial calculations of propellers and fans.

Design and Sizing of an Electrified Lift-Plus-Cruise Ducted Fan Aircraft

This paper demonstrates parametric definition and sizing of all-electric and hybrid-electric variants of a dual-purpose ducted fan lift-plus-cruise aircraft configuration. The dual roles include passenger transportation for urban air mobility as well as transportation of supplies and personnel for military applications. The impact of battery technology on the characteristics of the sized all-electric and hybrid-electric variants is analyzed. For the latter, turboshaft engines are incorporated to satisfy cruise power requirements and offset peak power requirements during vertical flight, at the expense of additional propulsion system weight. The net impact of this penalty is investigated as a function of battery technology and range. The aircraft is sized and analyzed using the Parametric Energy-based Aircraft Configuration Evaluator, a sizing framework utilizing a parametric geometry definition and resizing rule set for the aircraft, strip-theory-based aeropropulsive models, energy-based mission performance analysis, and a combination of empirical and physics-based mass properties analyses.

Sizing Methodology and Energy Management of an Air–Ground Aircraft with Turbo-Electric Hybrid Propulsion System

This paper proposes a distributed turbo-electric hybrid propulsion system (TEHPS) architecture for high-power and large-load air–ground aircraft (AGA). The composition of the turboshaft engine, hybrid energy storage system (HESS) as the power unit, distributed electric drive ducted fans, and wheels as the propulsion unit is determined. Firstly, the modeling of each component in the TEHPS is carried out, and system power, energy, and weight analysis are conducted under the different operating modes. Sizing parameters of main components are selected based on a genetic algorithm to obtain the optimal total weight and propulsion efficiency, and the energy management framework from the upper level to the lower level is completed by adopting an equivalent consumption minimum strategy and fuzzy logic control. Under the air–ground amphibious mission profile, the simulation results indicate that the TEHPS can achieve a 21.80% fuel consumption and CO2 emission optimization rate at the cost of 10.53% increase in the whole aircraft mass compared to the oil-only powertrain. The HESS can account for up to 29% and 33.56% of the energy and power ratios in the TEHPS, and reduce mass by 8.1% and volume by 3.77% compared to the single energy storage, which may provide theoretical insights for the powertrain composition form, sizing, and energy management of future hybrid air–ground aircraft.

Numerical Investigation of Ground Effect of Dual Ducted Fan Aircraft During Hovering Flight

Actuator disk method 기반의 유동 해석자를 이용하여 수직 이착륙 복합형 비행체 중 하나인 이중 덕트 팬 항공기에 대한 공력해석을 수행하고 관련 지면 효과를 분석하였다. 회전 격자 기법을 이용한 해석결과와의 비교를 통해, 지면 효과 분석을 위한 해석자의 특성과 정확도를 함께 평가하였다. 지면과의 거리에 따른 공력 성능과 유동장 특성을 분석하였다. 지면과의 거리가 가까울수록 팬 추력은 증가하지만, 덕트, 동체, 날개의 수직력 감소로 인한 총 수직력 및 제자리 비행 효율의 저하를 확인하였다. 동체 하부의 유동장 분석으로부터 팬 후류와 지면 간의 상호작용에 의해 발생하는 지면 와류와 분수 유동을 확인하고, 이들이 비행체 공력 성능에 미치는 영향을 분석하였다. 속도 프로파일 비교/검토를 통해 비행체로부터의 거리와 방향에 따른 기체 주변 아웃워시의 강도와 특성을 분석하였다. 또한 콜렉티브 피치각에 따른 지면효과의 영향을 확인하였다.

Composite observer-based robust model predictive control technique for ducted fan aerial vehicles

Composite observer-based robust model predictive control technique for ducted fan aerial vehicles

Improving the performance of ducted fans for VTOL applications: A review

Improving the performance of ducted fans for VTOL applications: A review

Thermal Benefits of a Cooling Guide Vane for an Electrical Machine in an Electric Ducted Fan

Equipped with a distributed electric propulsion system, eVTOL is the primary vehicle for future urban air mobility. The electrical machine determines the weight of the distributed electric propulsion system, and the cooling capability determines the electrical machine’s weight. The electrical machine with air cooling is preferred for eVTOL due to its simplicity and light weight. This paper presents a new air-cooling system for an electrical machine in an electric ducted fan propulsion system. The novel cooling system consists of a cooling guide vane with a heat pipe (CGVHP), which is located downstream of the ducted fan rotating blade. The heated end of the heat pipe is inserted into the stator end windings and the cold end is inserted into the cooling guide vane. The heat generated in the windings is transmitted to the cooling guide vane by the heat pipe and dissipated by the forced convection using low-temperature air passing through the ducted fan. The cooling performance of the cooling guide vane with the heat pipe was numerically simulated, considering several critical design factors. The simulation results showed that the proposed CGVHP can be helpful for reducing the winding temperature of the electrical machine by over 25.5 °C at the peak power condition of 15.7 kW.

Flying Washer: Development of High-Pressure Washing Aerial Robot Employing Multirotor Platform with Add-On Thrusters

In this study, we propose a multirotor aerial robot for high-pressure washing tasks at high altitudes. The aerial robot consists of a multirotor platform, an add-on planar translational driving system (ATD), a visual sensing system, and a high-pressure washing system. The ATD consists of three ducted fans, which can generate force in all directions on the horizontal plane. The ATD also allows the multirotor to suppress the reaction force generated by the nozzle of a high-pressure washing system and inject water accurately. In this study, we propose a method to precisely inject water by installing an ATD in the multirotor and using its driving force to suppress the reaction force and move the multirotor while keeping its posture horizontal. The semi-autonomous system was designed to allow the operator to maneuver the multirotor while maintaining a constant distance from the wall by the sensor feedback with onboard LiDAR or stereo camera. In the experiment, we succeeded in performing the high-pressure washing task in a real environment and verified that the reaction force generated from the nozzle was actually suppressed during the task.

Analysis of a HVAC zoning control system with an air-to-water heat pump and a ducted fan coil unit in residential buildings

• Thermal zoning control model is presented for hydronic air conditioning systems. • The control system conditions each zone of the building individually. • The control acts over the AWHP set point water temperature and the fan coil fan speed. • A comparison with a non-zoned ducted fan coil and individual fan coils is performed. • High thermal comfort and total energy savings until 40% are achieved in a dwelling. This paper presents an analysis of a thermal zoning system integrated in a Heating, Ventilation and Air-Conditioning (HVAC) system based on an air-to-water heat pump with a ducted fan coil. Zoned systems are based on independently controlling the temperature of each of the zones of a building. When a zone is not occupied or not in demand, the control board sends a control signal to the zone's motorised damper which interrupts the airflow supply to that room. Although this control system is gaining popularity in the residential sector, the results obtained in terms of thermal comfort and energy consumptions are not evident and should be documented. Besides, the control strategy is based on an algorithm that allows acting on the heat pump, setting the set-point temperature, and on the fan-coil, setting the fan speed. Based on this, it is possible to design an algorithm to optimize the performance of the installation ensuring thermal comfort and achieving energy savings. The thermal zoning and the HVAC control system are modelled and simulated in Trnsys17 for the case of study of a residential dwelling, compared with two different configurations: a non-zoned ducted fan coil and individual fan coils. Important benefits are obtained in the evaluation of thermal comfort, with higher values of PPD in all zones. From the point of view of energy consumption, the influence of the thermal zoning on the performance of the heat pump reports important energy savings. Finally, an economic analysis results in payback periods lower than 4.9 years.

Aerodynamic Characteristics of a Ducted Fan Hovering and Transition in Ground Effect

Ducted fans installed on vertical takeoff and landing vehicles experience significant ground effect during takeoff and landing. The aerodynamic characteristics of a ducted fan hovering and transitioning in the ground effect are studied using numerical simulations in this paper. The flowfields are obtained by solving Reynolds Averaged Navier–Stokes equations with the Multiple Reference Frame approach. When a ducted fan hovers in the ground effect, the blade thrust increases due to the combined effect of the increase in the effective angle of attack of the blade and the increase in ambient pressure; the duct thrust decreases due to the combined effect of the decrease in the effective angle of attack of the duct and the increase in ambient pressure. Stall occurs at a certain advance ratio and angle of attack when transitioning in the ground effect. The ground effect delays the occurrence of stall at some advance ratios. The ground effect is hardly detectable at angles of attack less than 30° even if the height drops to 0.5 times the duct exit diameter. At this height and high angles of attack, the different positions and influence regions of the ground vortex at different advance ratios contribute to the different variation trends in the ducted fan performance.

Acoustic radiation characteristics of cutoff modes from ducts

The acoustic radiation from a source inside a hard-walled semi-infinite duct or tube, such as for ducted fans and rotors, is investigated. In particular a study of cutoff modes, which have the potential to affect the far-field pressure radiation for sources close to the duct open end, is presented. A large amount of work has been done to mathematically and experimentally investigate propagating cuton acoustic modes. However, there is very little published work on the radiation of cutoff modes. This paper concerns the radiation characteristics of cutoff modes to determine their behaviour, and their likely influence in the far-field directivity for sources close to the duct open end. It is shown that cutoff modes are an essential contributor for the radiation in the rear-arc.

Оцінка тяги закапотованого співвісного гвинтовентилятора

One of the basic requirements for existing and future aircraft engines is high specific power, low specific fuel consumption, and low noise level. The current work evaluates the thrust of a ducted coaxial propfan. A coaxial propfan was chosen as the object under study. The peripheral diameter of the first and second rows of the propfan reaches 4.5 m. The number of blades of the first row of the propfan is 8, the second – 6. The duct had a length of 3.214 m and a maximum profile thickness of 0.23 m. For this study, a model of a coaxial propeller fan was made for a numerical experiment. The model created for the study was a cylinder with a radius of 75 m and a height of 150 m. A model of an open coaxial fan and a ducted coaxial fan was created in this cylinder. The simulation of the flow in a ducted and open coaxial propfan was carried out for a flight altitude of H=7534 m at a rotational speed of the first and second rows of the propfan at 850 rpm. The input Mach number was 0.52. Based on the results of the study, a histogram for evaluating the thrust of the ducted and open coaxial propfan was constructed. The simulation of the flow in assessing the thrust of a ducted and open coaxial propfan was carried out under the same flight conditions. The results of the study showed that the presence of a duct gives a fairly large increase in thrust - the thrust of a coaxial propfan increases by 82 %. However, note that the calculations do not consider the drag that the duct will create. Evaluation of the drag of the ducted is the next task of the study. The resulting visualizations of the flow around an open and ducted coaxial propfan demonstrate qualitative and quantitative changes in the values of the parameters under study during flow. It can be seen that in the presence of a duct, the total pressure behind the propfan increases significantly. Increasing the thrust of a ducted coaxial propfan makes it possible to reduce the rotational speed of the propfan to provide thrust similar to that of an open propfan, which will improve the acoustic characteristics of the propfan. Also, the acoustic radiation can be reduced by placing sound-absorbing structures in the duct.

Acoustic pre-design studies of ducted fans for small aircraft

This publication presents an analytical method for the aerodynamic and acoustic pre-design of ducted fans for small aircraft. Based on studies of the primary design variables, the paper discusses the physical sound generation phenomena, as well as the interdisciplinary relationships of ducted fan design. First, the fan design and analysis methods are described. On the basis of an aerodynamic mean line method, the radial distribution of the flow velocities is used to determine the steady blade flow. Unsteady aerodynamic excitations are calculated by means of Sears’ blade response function. To determine the generation and propagation of sound within the ducted fan, Goldstein’s acoustic analogy is solved analytically. The methods are applied to a reference case, for which studies show that ducted fans offer significant potential in reducing sound emission, compared to free propellers. Since the rotor-alone noise of subsonic ducted fans is always cut-off, tonal sound is predominantly excited by rotor–stator interactions. These sources can be significantly reduced by a proper selection of the rotor blade and stator vane numbers, as well as optimal lean and sweep of the stator vanes. Large diameters and axial gaps are acoustically advantageous, but reduce fan stage efficiency and increase nacelle drag due to large wetted areas, especially at cruise. As a result, the importance of considering these complex interdependencies in a comprehensive design approach is shown. The pre-design method presented can be used to determine an optimal ducted fan design, taking into account interdisciplinary trade-offs, with an emphasis on noise. Analysis of the ducted fan concept shows that the ducted fan can be a promising alternative to the free propeller, especially if low noise emission is required.

A Study on Hover Performance of Ducted Fans for an Unmanned VTOL Aircraft

In this study, ground tests and numerical analysis were performed to verify the hover performance of the second ducted fan model designed by this research team. Shape of the duct inner surface was asymmetric in longitudinal direction, and considering various aspects such as test site or costs for test operation, a 40% scaled-down model of the ducted fan was adopted for this study. Both the results of the tests and the analysis were found to be coherent, and it was verified that the ducted fan was verified to be well designed to achieve the targeted performance. Furthermore, the performance of this ducted fan was compared with that of the symmetric one to determine the effects of the difference in the duct shape on the performance. It was observed that the symmetric ducted fan performs better in hovering flight, although the asymmetric ducted fan was sufficiently satisfied with the design intention.

열-음향 상호작용을 고려한 라디에이터 홴 덕트 최적화 연구

Although radiators have been actively used to manage the high thermal energy of internal combustion engines, the market size is increasing despite the recent rapid growth of electric vehicles. Radiators for vehicles were usually used with fans for effective thermal management. Radiators and fans improved heat dissipation performance in various ways. However, the noise covered in the internal combustion engine is emerging as a new problem in electric vehicles. Accordingly, it is required to develop the radiator fan considering the aeroacoustic characteristics. Ducts that may affect heat dissipation performance are generally used for the noise reduction of the fans. Therefore, heat dissipation performance and aeroacoustic characteristics for three design variables determining the aspect ratio of the ducted radiator fan were analyzed in this study. The results calculated numerically were used for optimization after analysis using the response surface methodology. A clear difference in noise characteristics was found according to the receivers. The heat dissipation performance was more influenced by the duct than the noise, and the Nusselt number was improved by 2.54% through optimization. Appropriate duct optimization considering both heat dissipation performance and noise reduction is important to design the radiator fan.

Numerical Prediction of Unsteady Aerodynamics of a Ducted Fan Unmanned Aerial Vehicle in Hovering

Recently, ducted fan unmanned aerial vehicles (UAVs) have attracted considerable attention due to their potential for application in both civil and military missions. Compared with free propellers, the presence of duct can in principle decrease the flow contraction after propeller, and gives the potential to fly efficiently with high security, compact structure, and low noise. In the present study, a ducted fan UAV is designed using the open source code OpenProp. The computational fluid dynamics (CFD) simulation model using sliding mesh technique is established and validated as a reliable tool for highly vortical flows by propeller thrust experiment. The effect of the duct, revolution speed, and distance between propellers on the aerodynamic characteristics of the ducted fan UAV is evaluated in detail. Results show that the unducted coaxial upper and lower propellers generate 3.8%, 4.3% more thrust than the unducted single propellers, respectively, and the unducted upper and lower propellers generate 55.9%, 34.9% more thrust than ducted propellers, respectively. The ducted fan UAV generates 5.7% more thrust and consumes 39.1% less power than the unducted coaxial propellers. The thrust of the ducted fan UAV increases first and then follows with a decreased tendency as the distance between propellers increases.