Showing papers by "Dean Hu published in 2020"
TL;DR: In this paper, the effect of MTEF on the aerodynamic load control of a large-scale wind turbine blade was investigated in detail by a validated Computational Fluid Dynamic (CFD) model, in which a specially designed mesh update method was adopted.
18 citations
TL;DR: In this article, a study on thermoplastic single-lap double rivet joints with and without adhesive subjected to out-of-plane projectile impact and quasi-static concentrated loading is presented.
7 citations
TL;DR: A theoretical model coupled with oral cavity velocity and pressure in balaenid whales is established based on mass conservation, momentum conservation and pressure drop equations, considering both the inertial and the friction terms, and provides a reference for the design of high-efficiency bionic filters.
Abstract: Balaenid whales, as continuous ram filter feeders, can efficiently separate prey from water by baleen. The feeding process of balaenid whales is extremely complex, in which the flow distribution and pressure drop in the oral cavity play a significant role. In this paper, a theoretical model coupled with oral cavity velocity and pressure in balaenid whales is established based on mass conservation, momentum conservation and pressure drop equations, considering both the inertial and the friction terms. A discrete method with section-by-section calculation is adopted to solve the theoretical model. The effects of four crucial parameters, i.e., the ratio of filtration area to inlet area (S), the Reynolds number of entrance (Rein ), the ratio of thickness to permeability of the porous media formed by the fringe layer () and the width ratio of the anteroposterior canal within the mouth along the tongue (APT channel) to that along the lip (APL channel) (H) are discussed. The results show that, for a give case, the flow distribution and the pressure drop both show increasing trends with the flow direction. For different cases, when S is small, Rein is small and is large, a good flow pattern emerges with a smoother flow speed near the oropharynx, better drainage, better shunting and filtration, and higher energy efficiency. However, for smaller values of H, some energy efficiency is sacrificed to achieve additional average transverse flow in order to produce better shunting and filtration. The research in this paper provides a reference for the design of high-efficiency bionic filters.
6 citations
TL;DR: In this article, an electrically activated underwater suction device is designed to form an amazing amount of negative pressure by generating water swirling flow, which can make underwater wall-climbing robot stick to the wall surface allowing a ground clearance.
Abstract: An electrically activated underwater suction device is designed to form an amazing amount of negative pressure by generating water swirling flow, which can make underwater wall-climbing robot stick to the wall surface allowing a ground clearance. For the purpose of a full understanding of the mechanism of the suction device, a series of experimental tests are carried out and a computational fluid dynamics (CFD) model is established. The results show that the suction force F is consistent between experimental tests and simulations. An insight into the flow phenomena of vortex suction device, including spatial velocity and pressure distribution, is given through numerical simulation analysis. Furthermore, the crucial parameters, i.e., the rotation speed ω and gap clearance h, are studied. Then the relationships of F-ω and F-h are clarified. It reveals that with the increasing of rotation speed, the suction force increases quadratically. And with the increasing of gap clearance, the suction force increases firstly and then decreases, so that a reasonable design interval of gap clearance can be got to obtain the required suction force for the engineering applications.
3 citations
TL;DR: A theoretical model is established to analyze the hydrodynamic filtering system in the balaenid whales suspension feeding and shows that the particle trajectories consist of a series of backward-outward arcs and the food particles tend to accumulate in the posterior region of the oral cavity.
Abstract: Balaenid whales are giant filter feeders that feed on the dense aggregations of prey. Through their unique oral filters, they can effectively filter water out and leave prey in their mouths. In this study, a theoretical model is established to analyze the hydrodynamic filtering system in the balaenid whales suspension feeding. First, the appropriate velocity profiles in the anteroposterior and mediolateral directions are adopted to approximate the flow field in the anteroposterior channel along the tongue (APT channel). Then, a 4-stage Runge-Kutta method is used to calculate the particle trajectories and predict the corresponding filter cake profile by solving the particle motion equations. Finally, the effects of three crucial parameters, i.e., the APT channel widthDT, the fringe layer permeabilityK, and the food particle diameterdp, are discussed. The results show that the particle trajectories consist of a series of backward-outward arcs and the food particles tend to accumulate in the posterior region of the oral cavity. The growing parabolic filter cake profiles are formed except for the case of extremely low permeability. A smallDTand largeKmake the tendency of particle posterior aggregation obviously. So squeezing the tongue and having larger fringe layer permeability are both conducive to the swallowing process. But the change indphas less influence on this tendency. The proposed theoretical analysis method is a fast and low-cost calculation method. The study on the balaenid whales' filter feeding biomechanics and hydrodynamics is helpful to guide the design of the high-efficiency bionic filters.
2 citations
Patent•
17 Apr 2020
TL;DR: In this paper, a negative-pressure driving flexible torsional actuator is proposed, which consists of a top face, a helical structure and a bottom face, four helical cavities communicating with one another are distributed in the helical structures, and the upper face and the lower face of the structure are connected with the top face and bottom face respectively.
Abstract: The invention discloses a negative-pressure driving flexible torsional actuator. The negative-pressure driving flexible torsional actuator comprises a top face, a helical structure and a bottom face,four helical cavities communicating with one another are distributed in the helical structure, and the upper face and the lower face of the helical structure are connected with the top face and the bottom face respectively; the middle of the top face is provided with a convex vent hole, one end of a silica gel hose is inserted into the convex vent hole, and the other end of the silica gel hose isconnected with an air pump; and negative pressure is exerted to the helical cavities through the air pump, the helical cavities collaboratively collapse and deform, then the torsional actuator generates torsional motion, and when the negative pressure is released, the helical cavities quickly restore to the initial state. According to the negative-pressure driving flexible torsional actuator, themanufacturing cost is low, the mass is small, the response speed is high, the large torsional angle is achieved under small negative pressure driving, the risk of explosion failure due to the too large pressure does not exist, and the wide application prospect is achieved.