“音流学”——声音可视化在装置艺术中的表达

在新媒体技术蓬勃发展的背景下,声音可视化逐渐成为装置艺术作品中新兴的表现形式。本文以“音流学”这一特殊的角度为切入点,简单梳理了“音流学”与声音艺术、声音可视化之间的原理、关系等,以举例论证的方式探讨了“音流学”与声音可视化在装置艺术中的应用,积极地探寻声音可视化在装置艺术中的表达。进而对“音流学”在未来艺术与设计中的发展进行探讨并寄予其厚望。

Design of a continuously variable Mach-number nozzle

A design method was developed to specify the profile of the continuously variable Mach-number nozzle for the supersonic wind tunnel. The controllable contour design technique was applied to obtaining the original nozzle profile, while other Machnumbers were derived from the transformation of the original profile. A design scheme, covering a Mach-number range of3.0<Ma<4.0, was shown to illustrate the present design technique. To fully validate the present design method, computational fluid dynamics(CFD) analyses were carried out to study the flow quality in the test area of the nozzle. The computed results indicate that exit uniform flow is obtained with 1.19% of the maximal Mach-number deviation at the nozzle exit. The present design method achieves the continuously variable Mach-number flow during a wind tunnel running.

A Study on the Effect of Creative Chinese Characters Learning on the Ability to Learn Chinese Old Sayings and Idioms Using K-Pop Music Video

Music is an extraordinary bridge between people all over the world so much as to be called a universal language. Idols and B-boys stages are fun, touching, and fantastic. Today, South Korean students are excited and enthusiastic about their colorful dance moves. The study is about creative educational methods that use K-pop music videos to learn the proverbs and old words that our ancestors learned to keep in mind and teach. K-pop lyrics are a rich reflection of the experiences of life and the world in which people are living today. Accordingly, this study can present new teaching and learning method examples that are used in class related to the old language associated with K-pop lyrics and can also introduce interesting class materials.

Flux Induced by Multiplicative Dichotomous Noise

The transport of particles induced by multiplicative dichotomous noise for a system is investigated. The stationary probability current is derived. It is shown that, for the system studied by us, the spatial asymmetry is the ingredient for the nonzero stationary current.

Three-Dimensional Lattice Boltzmann Model for High-Speed Compressible Flows

A highly efficient three-dimensional （31）） Lattice Boltzmann （LB） model for high-speed compressible flows is proposed. This model is developed from the original one by Kataoka and Tsutahara [Phys. Rev. E 69 （2004） 056702]. The convection term is discretized by the Non-oscillatory, containing No free parameters and Dissipative （NND） scheme, which effectively damps oscillations at discontinuities. To be more consistent with the kinetic theory of viscosity and to further improve the numerical stability, an additional dissipation term is introduced. Model parameters are chosen in such a way that the von Neumann stability criterion is satisfied. The new model is validated by well-known benchmarks, （i） Riemann problems, including the problem with Lax shock tube and a newly designed shock tube problem with high Mach number; （ii） reaction of shock wave on droplet or bubble. Good agreements are obtained between LB results and exact ones or previously reported solutions. The model is capable of simulating flows from subsonic to supersonic and capturing jumps resulted from shock waves.

Ultrasonic tomography and its applications in oilfield

UTT （Ultrasonic Tomography Tool） is widely used in the oil industry and can be used to inspect corrosion, casing wall damage, casing breakoff, and casing distortion in the well borehole with the maximum environment temperature being 125 ℃, and the pressure being 60 MPa. UTT consists of tool head, upper centralization, electronic section, lower centralization, transmitters, and receivers. Its outer diameter is 4.6 cm and length is 320 cm. The measured casing diameter ranges from 60 mm to 254 mm. The tomography resolution is 512×512. The borehole measurement accuracy is 2 mm. It can supply 3D pipe tomography, including horizontal and vertical profile. This paper introduces its specification, measurement principle, and applications in oilfield.

Reducing the Gas Pressure Drop in Suction Mufflers of Hermetic Reciprocating Compressors

The suction muffler of hermetic reciprocating compressors is installed in order to attenuate the noise generated by the gas pulsation of the flow through the suction valve. However, the installation of the suction muffler affects the operation of the compressor owing to gas pressure drop, which causes volumetric and energetic efficiency loss due to the gas specific volume augmentation. Therefore, there is a compromise between sound attenuation and pressure drop increase, which has to be taken into account by compressor designers. In this work, it presents a numerical solution to the flow through a suction muffler in order to analyze the pressure field and point out the main contributions to the overall pressure drop of the flow. A commercial CFD （computational fluid dynamics） code was used to perform the numerical simulations and the results were validated by using experimental data. After analyzing the pressure field, the geometry of the muffler was modified intending to decrease the flow pressure drop. The geometric modification produced a 28% reduction on the overall pressure drop, without influencing the sound attenuation.

Impact of Clocking on the Aero-Thermodynamics of a Second Stator tested in a One and a Half Stage HP Turbine

This paper focuses on the experimental investigation of the time-averaged and time-accurate aero- thermodynamics of a second stator tested in a 1.5 stage high-pressure turbine. The effect of clocking on aerodynamic and heat transfer are investigated. Tests are performed under engine representative conditions in the VKI compression tube CT3. The test program includes four different clocking positions, i.e. relative pitch-wise positions between the fh-st and the second stator. Probes located upstream and downstream of the second stator provide the thermodynamic conditions of the flow field. On the second stator airfoil, measurements are taken around the blade profile at 15, 50 and 85% span with pressure sensors and thin-film gauges. Both time-averaged and time-resolved aspects of the flow field are addressed. Regarding the time-averaged results, clocking effects are mainly observed within the leading edge region of the second stator, the largest effects being observed at 15% span. The surface static pressure distribution is changed locally, hence affecting the overall airfoil performance. For one clocking position, the thermal load of the airfoil is noticeably reduced. Pressure fluctuations are attributed to the passage of the up- stream transonic rotor and its associated pressure gradients. The pattern of these fluctuations changes noticeably as a function of docking. The time-resolved variations of heat flux and static pressure are analyzed together showing that the major effect is due to a potential interaction. The time-resolved pressure distribution integrated along the second stator surface yields the unsteady forces on the vane. The magnitude of the unsteady force is very dependent on the clocking position.

Lateral variation in seismic velocities and rheology beneath the Qinling-Dabie orogen

The Qinling-Dabie orogen is an important tectonic belt that trends east-west and divides continental China into northern and southern parts.Due to its strong deformation,complicated structure,multiphase structural superposition and the massive exposed high and ultrahigh metamorphic rocks,its tectonic formation and geodynamical evolution are hot research topics worldwide.Previous studies mainly focused on the regional geological or geochemical aspects,whereas the geophysical constraints are few and isolated,in particular on the orogenic scale.Here,we integrate the available P- and S-wave seismic and seismicity data,and construct the rheological structures along the Qinling-Dabie orogen.The results demonstrate that:(1)there are strong lateral variations in the crustal velocity between the western and eastern sections of the Qinling-Dabie orogen,indicating the different origin and tectonic evolution between these two parts;(2) the lateral variations are also manifested in the rheological structure.The rigid blocks,such as South China and Ordos basin(North China Craton),resist deformation and show low seismicity.The weak regions,such as the margin of Tibet and western Qinling-Dabie experience strong deformation and accumulated stress,thus show active seismicity;(3) in the lower crust of most of the HP/UHP terranes the values of P-wave velocity are higher than the global average ones;finally(4) low P- and S-wave velocities and low strength in the lower crust and lithospheric mantle beneath Dabie indicate lithospheric delamination,and/or high temperature,and partial melting condition.

Aero-Acoustics of Modern Transonic Fans—— Fan Noise Reduction from Its Sources

The noise of aerodynamics nature from modern transonic fan is examined from its sources with the perspective of noise reduction through aero-acoustics design using advanced Computational Fluid Dynamics (CFD) tools. In particular the problems associated with the forward propagating noise in the front is addressed. It is identified that the shock wave spillage from the leading edge near the fan tip is the main source of the tone noise. Two different approaches have been studied to reduce the forward arc tone noise and two state-of-art transonic fans are designed using the strategies developed. The following rig tests show that while the fans exhibit other noise problems, the primary goals of noise reduction have been achieved through both fans and the novel noise reduction concept vindicated.

Dynamical separation of rigid bodies in supersonic flow

A computational investigation of the unsteady separation behavior of rigid bodies in Mach-4 flow is carried out. Two rigid bodies, a sphere and a cube, initially stationary, centroid axially aligned, are released and thereafter fly freely according to the aerodynamic forces experienced. During the separation process, the smaller cube can experience different types of movement and our principal interest here is the non-dimensional transverse velocity of it. The separation behavior is investigated for interactions between a sphere and a cube with different mass ratio and a constant initial distance between them. The qualitative separation behavior and the final transverse velocity of the small body are found to vary strongly with the mass ratio but less sensitive to the initial distance between the two bodies. At a critical mass ratio for a given distance, the smaller body transit from entrainment within the flow region bounded by the larger body's shock to expulsion and the accumulated transverse velocity of the small body is close to maximum. This phenomenon is the so-called ‘shock-wave surfing' phenomenon noted by Laurence & Deiterding for two spheres at hypersonic Mach numbers. Then we investigate the separation behavior of a sphere interaction with a rotary cube and with a non-rotary cube for a given mass ratio and different distance between them. The rotary is found to increase the likelihood of ‘surfing'. Only at a certain initial distance for a given mass ratio the rotary effect of cube can be neglectable.

Ignition, flame propagation and extinction in the supersonic mixing layer flow

The supersonic mixing layer flow,consisting of a relatively cold,slow diluted hydrogen stream and a hot,faster air stream,is numerically simulated with detailed transport properties and chemical reaction mechanisms.The evolution of the combustion process in the supersonic reacting mixing layer is observed and unsteady phenomena of ignition,flame propagation and extinction are successfully captured.The ignition usually takes place at the air stream side of braid regions between two vortexes due to much higher temperature of premixed gases.After ignition,the flame propagates towards two vortexes respectively located on the upstream and downstream of the ignition position.The apparent flame speed is 1569.97 m/s,which is much higher than the laminar flame speed,resulting from the effects of expansion,turbulence,vortex stretching and consecutive ignition.After the flame arrives at the former vortex,the flame propagates along the outer region of the vortex in two branches.Then the upper flame branch close to fuel streamside distinguishes gradually due to too fuel-riched premixed mixtures in the front of the flame and the strong cooling effect of the adjacent cool fuel flow,while the lower flame branch continues to propagate in the vortex.

Effect of Boundary Layer Trip on Reduction of Jet Noise in Over-Expanded Nozzle Flow

A flow resonance accompanied by the emission of acoustic tones occurs in an over-expanded convergent-divergent(C-D) nozzle when operated at comparatively low pressure ratios. This phenomenon is distinguished from conventional screech tones and is referred to as "transonic tones". In contrast to screech tones, the peak resonant frequency for transonic tones increases with pressure ratio; the peak sound pressure level exceeds 110 d B. In this study, we investigated the basic characteristics of transonic resonance and tones using a circular C-D nozzle in an anechoic room. The effects of the boundary layer trip were also evaluated using a tripping wire for the suppressing transonic resonance and tones. The results of acoustic measurements show that several predominant peaks correspond to transonic tones. However, the boundary layer trip inside the nozzle effectively eliminated these tones and suppressed the unsteadiness of the flow inside the nozzle.

An aerodynamic design and numerical investigation of transonic centrifugal compressor stage

In the present paper,the design of a transonic centrifugal compressor stage with the inlet relative Mach number about 1.3 and detailed flow field investigation by three-dimensional CFD are described.Firstly the CFD program was validated by an experimental case.Then the preliminary aerodynamic design of stage completed through in-house one-dimensional code.Three types of impellers and two sets of stages were computed and analyzed.It can be found that the swept shape of leading edge has prominent influence on the performance and can enlarge the flow range.Similarly,the performance of the stage with swept impeller is better than others.The total pressure ratio and adiabatic efficiency of final geometry achieve 7:1 and 80% respectively.The vane diffuser with same airfoils along span increases attack angle at higher span,and the local flow structure and performance is deteriorated.

Investigation on transonic flutter active auppression with CFD-Based ROMs

The calculation of accurate unsteady aerodynamic forces is critical in the analysis of aeroelastic problems,however the efficiency is low because of high computational costs of the computational fluid dynamics(CFD)portion.Additionally,direct integrated CFD and computational structural dynamics(CSD)technique is unsuitable for the analysis of ASE and the flutter active suppression in state-space form.A reduced-order model(ROM)based on Volterra series was developed using CFD calculation and used to predict the flutter coupled with the structure.The closed-loop control systems designed by the sliding mode control(SMC)and linear quadratic Gaussian(LQG)control were constructed with ROM/CSD to suppress the AGARD 445.6wing flutter.The detailed implementation of the two control approaches is presented,and the flutter suppression effectiveness is discussed and compared.The results indicate that SMC method can make the controlled object response decay to the stable equilibrium more rapidly and has better control effects than the LQG control.

A new cascade-less engine operated from subsonic to hypersonic conditions: designed by computational fluid dynamics of compressible turbulence with chemical reactions

By using our computational fluid dynamic models, a new type of single engine capable of operating over a wide range of Mach numbers from subsonic to hypersonic regimes is proposed for airplanes, whereas traditional piston engines, turbojet engines, and scram engines work only under a narrower range of operating conditions. The new engine has no compressors or turbines such as those used in conventional turbojet engines. An important point is its system of super multijets that collide to compress gas for the transonic regime. Computational fluid dynamics is applied to clarify the potential of this engine. The peak pressure at the combustion center is over 2.5 MPa, while that just before ignition is over 1.0 MPa. The maximum power of this engine will be sufficient for actual use. Under the conditions of higher Mach numbers, the main intake passage located in front of the super multijet nozzles, takes in air more. That results in a ram or scramjet engine for supersonic and hypersonic conditions.

Experimental and Analytical Analysis of Perforated Plate Aerodynamics

Perforated walls and transpiration flow play an important role in aerodynamics due to an increasing interest in application of flow control by means of blowing and/or suction. An experimental study was carried out which has led to the determination of a transpiration flow characteristics in the form of a simple formula that is very useful in modelling such flows. In connection to this relation a method of 'aerodynamic porosity' determination has been proposed which is much more reliable than geometric description of the porosity. A theoretical analysis of the flow through a perforation hole was also carried out. The flow was considered as compressible and viscous. The gasdynamic analysis led us to a very similar result to the relation obtained from the experiment. The adequacy of the theoretical result is discussed in respect to the experiment.