反射式红外传感器在智能型节水系统中的应用

利用反射式红外传感器和少量的电子器件(单稳态触发器),研制了智能型节水控制系统。该系统能够识别是否有人入厕,酌情产生冲洗信号, 躯动进水电磁阀开启,向浮球式水箱内注水,待注满足以冲刷干净所需的两水箱水后,便自动地切断电磁阀中电源,达到了既卫生又节约的目的。在某一教学楼应用该系统一年多来,与无使用此系统的同规模另一教学楼相比,节水约70％。该系统元件少、成本低、结构合理、工作可靠、安装容易、维修方便,有广阔的应用前景。     

心瓣流体动力学研究进展

心瓣流体动力学是近年来才形成的一门新兴边缘学科分支。本文比较全面地介绍了该学科的主要研究内容、研究特点、发生发展的历史和现状,以及笔者及其同事在这方面的工作,提出并论述了对学科发展有重大影响的几个富有挑战性的问题,从而预示了学科的发展方向      

Simplex space-time meshes in compressible flow simulations

Employing simplex space-time meshes enlarges the scope of compressible flow simulations. The simultaneous discretization of space and time with simplex elements extends the flexibility of unstructured meshes from space to time. In this work, we adapt a finite element formulation for compressible flows to simplex space-time meshes. The method obtained allows, for example, flow simulation on spatial domains that change topology with time. We demonstrate this with the two-dimensional simulation of compressible flow in a valve that fully closes and opens again. Furthermore, simplex space-time meshes facilitate local temporal refinement. A three-dimensional transient simulation of blow-by past piston rings is run in parallel on 120 cores. The timings point out savings of computation time gained from local temporal refinement in four-dimensional space-time meshes.     

等离子体电磁加速器中快速电磁阀气体注入特性研究

在注气持续时间短、注入气体质量大的快速电磁阀测量中，采用高频响应压力传感器在电磁阀出口测量了气体的动态压力，通过真空室注气前后的压强差测量了注入气体的质量。研究表明，驱动电流、位移限定以及背景气压对气体注入特性有显著影响。当阀片受到的电磁力远大于背景气压造成的阻力时，增大驱动电流和增大背景气压都会加速流道口气体流动，提高气体注入量；电磁阀最高流速超过当地声速，流道应该设计成扩张式，且流道的长度要求尽可能短；电磁阀的注气持续时间主要由阀片的运动时间以及阀片关闭后气体在流道内扩散速率决定的。     

单向开口阀式Savonius水轮机及其水动力性能研究

为提高Savonius水轮机的能量捕获效率, 提出一种单向开口阀式Savonius转子设计. 建立转子三维数值模型, 仿真分析转子叶片开口率和曲率等参数对水轮机性能以及减流效果的影响. 最后, 搭建实验平台, 开展物理模型对照实验, 验证数值模拟结果的准确性. 结果显示, 叶片的曲率半径较大且开口率较小时, S型水轮机的水动力性能有效提升; S型转子开口率为0.2时, 性能平均比无开口的S型转子提升33.57%; 当叶片的曲率半径在50~之间时, S型转子具有较好的减流效果, 在S型转子后方范围内, 可减少35%的流速.     

Characterization of Astaxanthin Nanoemulsions Produced by Intense Fluid Shear through a Self-Throttling Nanometer Range Annular Orifice Valve-Based High-Pressure Homogenizer

Stable, oil-in-water nanoemulsions containing astaxanthin (AsX) were produced by intense fluid shear forces resulting from pumping a coarse reagent emulsion through a self-throttling annular gap valve at 300 MPa. Compared to crude emulsions prepared by conventional homogenization, a size reduction of over two orders of magnitude was observed for AsX-encapsulated oil droplets following just one pass through the annular valve. In krill oil formulations, the mean hydrodynamic diameter of lipid particles was reduced to 60 nm after only two passes through the valve and reached a minimal size of 24 nm after eight passes. Repeated processing of samples through the valve progressively decreased lipid particle size, with an inflection in the rate of particle size reduction generally observed after 2–4 passes. Krill- and argan oil-based nanoemulsions were produced using an Ultra Shear Technology™ (UST™) approach and characterized in terms of their small particle size, low polydispersity, and stability.     

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针对机载武器发射产生的废气对发动机工作参数的影响，自行研制了微压差压力传感器来测 量发动机压气机后压力的突降信号，及时打开防喘系统来防止发动机喘振或停车. 论述了传 感器的结构、工作原理和设计思路以及主要组件参数的设计方法，并得出符合设计要求的试 验结果.     

Estimating diverter valve corrections

A new method has been developed for estimating the corrections to be made to the measured time interval for diverter valves used in primary liquid flow measurement facilities. The model relates the mass flowrate, m, to the measured mass of liquid collected and the effective collection time. The effective collection time is the sum of the measured time interval and the diverter valve correction, τ, to be estimated. The diverter valve correction is the adjustment made to the collection time to account for the non-instaneous diversion of the flow between the collection vessel and the reservoir of the flow loop. An auxiliary flow measurement device in the flow pipeline is used to estimate m and an iterative process is used in the estimation of τ. This method gives statistical information on the variability of the performance of the system as indicated by the individual estimates of τ. Experimental data for two diverters used in the US National Bureau of Standards Primary Liquid Flow Measurement Facility are used to illustrate the calculation procedure     

‘Pop’ safety valves: a compressible flow analysis

Pressure versus lift characteristics of Pop-type safety valves have been predicted from a model in which pressures on various parts of the valve disc can be deduced from compressible flow analysis of three passages in series. In particular, it has been shown that the characteristic snap-open and snap-shut phenomena are inherent in the solutions to the sets of equations, and are critically dependent on the setting of the adjusting ring, bearing out what is known in practice. The model has shown satisfactory agreement with experimental data from a $\text{1}\text{2}\text{″}$ (12.55 mm) pop valve operating in air.     

Numerical Investigation and Feasibility Study of a PZT-driven Micro-valve Pulsed-jet Actuator

A micro-valve pulsed-jet vortex-generator driven by piezoelectric actuation was successfully modelled numerically to determine the feasibility of such a design. This includes: modelling the dynamic motion of a unimorph cantilever and the fluid-structure interaction occurring between the unimorph and the fluid flowing over such a structure; the unsteady developing channel flow that would occur through the outlet orifice was also modelled. The initial design was found to have several fundamental flaws that were shown to be easily remedied. The fluid-structure interaction was found to have a strong effect on the motion of the piezoelectric beam and therefore the performance of the pulsed-jet actuator. The response time of the actuator was found to be governed by the micro-valve opening rather than the time taken to establish the jet. However, the resistance of the pulsed-jet actuator was shown to be governed by the outlet orifice; it was an order of magnitude larger than the resistance of the micro-valve.