Influence of the rotor propulsor on the characteristics of the power unit integrated with wing

Fan wing concept increased the efficiency of using the kinetic energy of the movement of air that flows around the wing. It allow generate thrust and lifting forces. But this scheme also has drawbacks. The most important associated with the significant drag force. The large diameter of the cross-flow fan, in case of failure of the power plant, the aerodynamic quality will be approximately 1: 3. To improve parameters and increase the feasibility of using this scheme, we need to review the existing concepts and change the basic geometric parameters of the cross-flow fan and try to reduce the diameter. It is advisable to increase the speed of its rotation. This work performed calculation and compare lift force and thrust force generated by the system. Compare various positions of the blades, and airflow rate at the outlet of the engine by numerical simulation. Also studied the effect of the profile shape of the blades and their amounts on the performance. As a result, analysis of the interaction of all these parameters to determine the model with the best aerodynamic performance. Numerical modeling turned out to be very resource-intensive. So the main focus on a series of physical experiments with real models. The results show that this scheme has more benefits when compared with before use. So, the proposed idea has good prospects for development and application.

Emergency Flight Control Based on the Fan Wing

FanWing has been taken to the visual field because of its performance combination of fixed-wing aircraft and helicopter. Its flight mode is currently limited mainly by a remote control, while the research of automated flight control is on the rise. The fan wing could offer lift, thrust, and the additional pitch moment for longitudinal control. At the same time, the roll moment and the yaw moment can be generated by the differential rotation of the cross-flow fan to realize the lateral control. It provides the possibility for its emergency flight control when the aerodynamic control becomes inefficient at a low speed. The difficulties in designing the emergency control system in both the longitudinal and lateral controls are analyzed. And it emphasizes the importance of selecting its center of gravity and the emergency control method of longitudinal control in engineering. The simulation results show that as an emergency flight control system, fan wing control is feasible. The study of the fan wing control will provide a reference solution for its further engineering applications.

Aeroacoustic simulation of a cross-flow fan using lattice Boltzmann method with a RANS model

The present study developed an unsteady RANS approach based on the lattice Boltzmann method (LBM), which can perform direct aeroacoustic simulations of low-speed fans at lower computational cost compared with the conventional LBM-LES approach. In this method, the k-ω turbulence model is incorporated into the LBM flow solver, where the transport equations of k and ω are also computed by the lattice Boltzmann method, similar to the Navier-Stokes equations. In addition, moving boundaries such as fan rotors are considered by a direct-forcing immersed boundary method. This numerical method was validated in a two-dimensional simulation of a cross-flow fan. As a result, the simulation was able to capture an eccentric vortex structure in the rotor, and the pressure rise by the work of the rotor can be reproduced. Also, the peak sound of the blade passing frequency can be successfully predicted by the present method. Furthermore, the simulation results showed that the peak sound is generated by the interaction between the rotor blade and the flow around the tongue part of the casing.

Multi-condition optimization of a cross-flow fan based on the maximum entropy method

Cross-flow fans are widely used in heating, wind-curtains, and air-conditionings, as well as other ventilation systems. A single or double arc is generally used as the camber line of cross-flow fans, but this design leads to constraints in the geometry of the blade profiles. In this study, the camber line of a cross-flow fan blade was parameterized by five parameters based on the fourth-order Bezier curve. A two-dimensional computational fluid dynamics (CFD) simulation was conducted to predict the aerodynamic characteristics and the internal flow field. It is necessary in multi-condition optimization, to evaluate the relative importance of the performance parameters under different working conditions and determine their weight factors. Here, a novel maximum entropy method (MEM) was proposed to quantify of volume flow rate, because the method avoids the subjectivity in the selection of the weights. Subsequently, a multi-island genetic algorithm (MIGA), combined with numerical simulation, was used to search the global optimum in the given design space. The results indicated that the optimum combination of the structural parameters reduced the blade channel vortex in a particular location of the impeller and changed the position and size of the eccentric vortex. The volume flow rate of the optimized impeller was 4.28% higher at the minimum rotation speeds and 12.87% higher at the maximum rotation speeds.

Design and Experiment of Vibrating Screen Millet Cleaning Devise with Double-fan

HighlightsAccording to the physical characteristics of the millet, the double-layer mesh vibrating screen was used as the cleaning screen to prolong the cleaning time of the millet in the cleaning room, prevent the blocking of the vibrating screen, and improve the cleaning performance of the millet cleaning device.As the air flow produced by centrifugal fan was continuously attenuated on the screen surface, the draft chaser cannot completely discharge the chaffs, stalks and other sundries outside the machine. The cross-flow fan designed at the tail of the vibrating screen worked well for increasing the air flow field, improving the cleaning performance.In order to reduce the unthreshed grain-codes in the threshed mixture, a re-threshing device was installed for the millet cleaning device that transported sundries at the end of the screen to the main threshing roller for re-threshing, which improved the cleaning rate and reduced the loss rate effectively.The mathematical model of four factors quadric regression between the rotating speed of centrifugal fan, cross-flow fan, frequency of vibrating screen, width of sundry outlet and the cleaning performance of the device was established, which was meaningful and had high fitting degree. The results of indoor test shown that the cleaning rate was 98.8% and the loss rate was 1.3%.The results of bench test and field test shown that when the size of the upper screen was 12×12 mm, the size of the lower screen was 6×6 mm, the diameter of the suction port of the cross-flow fan was 15 mm, the rotating speed of the centrifugal fan was 1406 r/min, the rotating speed of the cross-flow fan was 713 r/min, the frequency of the vibrating screen was 5.9 Hz, and the width of the sundry outlet was 178 mm, the cleaning rate of the millet cleaning device was 98.75%, and the loss rate was 1.34%.Abstract. The cleaning device is an important part of the millet combine harvester, which directly affects the performance of the whole machine. Aiming at the problems of low cleaning rate and high loss rate in the traditional air-and-screen cleaning device, a vibrating screen millet cleaning device with double-fan was designed. The structure and relevant parameters of the vibrating screen millet cleaning device with double-fan were analyzed and determined. The effects of the rotating speed of centrifugal fan, the rotating speed of cross-flow fan, the vibrating frequency of vibrating screen and the width of the sundry outlet on the millet cleaning rate and the loss rate were studied by single factor test and the orthogonal combination test of four element quadratic rotation. The regression equation between the rotating speed of centrifugal fan, the rotating speed of cross-flow fan, the vibrating frequency of vibrating screen and the width of the sundry outlet and the millet cleaning rate and the loss rate are constructed was used to optimize and obtain the operation parameters of the cleaning device. The indoor test results showed that when the centrifugal fan speed was 1406 r/min, the cross-flow fan speed was 726 r/min, the vibrating screen frequency was 5.9 Hz, and the width of the sundry outlet was 178 mm, the millet cleaning rate was 98.8%, and the loss rate was 1.3%. The result of field test showed that the cleaning rate and loss rate of the vibrating screen millet cleaning device with double-fan were 98.75% and 1.34%, respectively. Keywords: Double-fan, Double-layer mesh vibrating screen, Field test, Millet.

Feasibility Study of a Multi-Purpose Aircraft Concept with a Leading-Edge Embedded Cross-Flow Fan

The research presented focuses on investigating the use of Cross-Flow Fan (CFF) as a high-lift device for a Short Take-off and Landing (STOL) aircraft. The wing-embedded fan performance analysis is mostly addressed from an aerodynamic perspective and focuses on using such Active Flow Control (AFC) technology in the conceptual aircraft design process. In particular, the design trade study of an aircraft featuring the fan as a high-lift device applied to a conceptual design of a medium-range multi-purpose aircraft is performed. A sensitivity analysis is employed to investigate the impact of the technology on the aircraft weight, aerodynamics, stability and control, and fight performance. The aircraft design modifications are introduced to maximize the aircraft mission performance given the fan specifications and constraints. Results indicate a reduction of the take-of field length by 18% with the payload penalty of 14%. The aircraft ferry range is also decreased by 7% compared to the baseline aircraft design. The scaling analysis of the aircraft concept is performed to determine the potential market for such technology. The results show that a light General Aviation (GA) airplane or a medium-large size Unmanned Aerial Vehicle (UAV) could benefit more from the wing-embedded CFF compared to more heavy airplanes.