Combined heat, air, moisture and pollutants transport (CHAMP) exists across multi-scales of a building environmental system (BES): around the building, through the building shell/envelope, inside a multizone building, and in the micro-environments around occupants. This paper reviews previous work and presents a system model for simulating these transport processes and their impacts on indoor environmental quality. Components of the system model include a multizone network flow model for whole building, a room model for air and pollutant movement in ventilated spaces, a coupled heat, air, moisture, and pollutant transport model for building shell, an HVAC model for describing the dynamics of the heating, ventilating and air-conditioning (HVAC) system, and shared databases of weather conditions, transport properties of building materials, and volatile organic compounds (VOCs) emissions from building materials and furnishings. The interactions among the different components, and challenges in developing the CHAMP system model for intelligent control of BES are also discussed.

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Characteristics of the self-assembled poly(dA)·poly(dT) DNA network adhered on the mica substrate are experimentally investigated based on the AFM observations and the fractal dimension analysis. Artificial B-type double stranded DNA, which consists of 50 base pairs of adenine and thymine, is specially prepared for the experiment. The manufacturing process of DNA network is done in the aqueous solution of poly(dA)·poly(dT) DNA, and the systematical experimental runs are made for various concentration of the solution. It is found that the 2D fractal dimension strongly depends on the fabrication process of the DNA network.

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To investigate the detailed mechanism underlying double-stranded DNA (dsDNA) breaks caused by electron or photon impact, a physical model is proposed and ab initioquantum chemical calculation is employed. In our model, we neglect the backbone of DNA and focus on the interaction between a hydroxyl radical and a single-base pair. By Becke’s three-parameter hybrid Lee-Yang-Parr (B3LYP) functionals method based on a density functional theory, we calculate the optimized structure of base pair-hydroxyl radical complex by the energy minimization. The results suggest that the hydroxyl radical can stably exist near the hydrogen bond between adenine and thymine, or between guanine and cytosine. Consequently, we have found that the hydroxyl radical weakens the hydrogen bonds and the corresponding bond length of the base pair in dsDNA increases.

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For efficient aerodynamic design optimization, a discrete adjoint code is developed from an unstructured hybrid mesh Navier-Stokes solver. The adjoint code is verified by comparison of flux Jacobian and objective function gradient with a finite difference method. An aerodynamic design tool is developed utilizing the flow solver, adjoint code and a gradient-based optimizer and applied to a design example of a high-lift device. Use of prism layer grid sensitivities is suggested for more efficient gradient calculation from the adjoint analysis of Navier-Stokes equations with unstructured hybrid mesh.

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An efficient aeroelastic analysis where both aerodynamic and structural nonlinearities are considered is performed. The analysis is based on the computational fluid dynamics (CFD) and computational structural dynamics (CSD) techniques in the time domain. Moving shock wave on the lifting surface, which is the aerodynamic nonlinearity in this study, is taken into account using the transonic small disturbance (TSD) equation. Freeplay, which is the local structural nonlinearity, is considered in the modal coordinate using fictitious mass method. The aeroelastic response results of a wing with freeplay are presented in the subsonic and transonic regions. Also, the effects of an airfoil thickness on the aeroelastic responses are investigated.

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A nonlinear aeroelastic analysis system has been developed using the coupled numerical techniques of computational fluid dynamics (CFD) and computational structural dynamics (CSD) in the present study and the analysis system has been applied to an actual aircraft design procedure to examine aeroelastic stabilities. An aerodynamic analysis is performed using the transonic small disturbance (TSD) theory for computational efficiency and the results are compared with experimental data. An aeroelastic analysis in the time domain is performed to obtain the flutter boundaries of the aircraft model. Finally, the various effects of launchers and control surfaces are investigated.

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In this paper we illustrate a new method for design of wings based on the optimization of the performance stability. This technique is an alternative approach to the traditional one which considers just a design point and tends to “over-optimize”, producing solutions that perform well at the design point but have poor off-design characteristics. This method has been implemented for wing design in transonic field, searching for solutions that are stable in terms of performance with the fluctuations of Mach number and angle of attack. The high fidelity simulation has been performed with a Navier-Stokes code and a multi objective genetic algorithm has been used to optimize; in fact it has been proved that the design of airfoils, where the performance (lift and drag) and the stability are both objectives, is implemented more efficiently using a multi objective approach. In the optimization phase in order to reduce the number of needed simulations a response surface based on statistics (DACE) will be used.

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This paper describes the use of integrated multidisciplinary analysis and optimization of a race car model on a predefined circuit. The objective is the definition of the most efficient geometric configuration that can guarantee the lowest lap time. In order to carry out this study it has been necessary to interface the design optimization software modeFRONTIER with the following softwares: CATIA v5, a three dimensional CAD software, used for the definition of the parametric geometry; A.D.A.M.S./Motorsport, a multi-body dynamic simulation software; IcemCFD, a mesh generator, for the automatic generation of the CFD grid; CFX, a Navier-Stokes code, for the fluid-dynamic forces prediction. The process integration gives the possibility to compute, for each geometrical configuration, a set of aerodynamic coefficients that are then used in the multiboby simulation for the computation of the lap time. Finally an automatic optimization procedure is started and the lap-time minimized. The whole process is executed on a Linux cluster running CFD simulations in parallel.

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In recent years, the Lattice Boltzmann Method (LBM) has been developed as an alternative numerical approach in Computational Fluid Dynamics (CFD). In particular, this method is promising for simulations of multiphase and multi component fluid flow involving complex interfacial dynamics. Unlike the conventional CFD methods based on NS equations, the LBM is based on the mesoscopic particle’s kinetic equation. This method has some advantages such as the simplicity of the algorithm (high efficiency on parallel processing), flexible reproduction of interfaces between phases. The conventional LBM, however, requires regular structured grids. But, for complex flow field, unstructured grids should be used. In this study, we describe a computational scheme based on two-dimensional unstructured grids using Cubic Interpolation with Volume/Area coordinates (CIVA) method and Adaptive Mesh Refinement method. As examples of tests of this scheme, single and two-phase flow simulations are presented.

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In this paper, advanced drag prediction methods based on the momentum conservation theorem were applied to CFD computational results. These methods can decompose total drag into drag components such as wave, viscous and induced drag as well as spurious drag attributed to numerical computations. Hence the more accurate drag prediction is possible by the elimination of the spurious drag term. The computational results showed that the advanced methods had the good capability of drag prediction and meaningful drag decomposition with accuracy. It was also found that the predicted physical drag values were weakly dependent on the mesh quality.

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Fluid dynamics applications require a good understanding of the underlying physical phenomena. Therefore, effective procedures are necessary for analyzing and visualizing the various physical fields. Beside interactive and perceptually efficient techniques for visualizing flow fields directly, there is strong demand for methods that uncover hidden flow structures. Some recently developed feature based visual analysis methods are exemplarily presented. Fluid flow data typically are large and often are stored remotely or distributedly. The interactive visual analysis of such large data sets requires new software architectures ─ ideally utilizing emerging Grid standards. We discuss such architectures and report on specific software realizations.

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We developed a 3D modeling and displaying system for volume communication, which consists of a set of cameras and a PC cluster, and evaluated on both LCD and omni-directional displays. In this paper, we propose a parallel voxel coloring method for accelerating the 3D modeling process. By using a system consisting of five cameras and a six-node PC cluster, it was possible to model and display a real-world object at interactive frame rate. We also investigated the use of an omni-directional display and verified the effectiveness of sharing the same reconstructed object, showing the potential to become an important tool for volume communication.

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Scientific collaborative visualization based on visual data mining is an efficient approach for facilitating the intellectual discovery and understanding the visualization data obtained from large-scale ata sets. We think that Collaborative Virtual Environment (CVE) is one of the efficient method to achieve collaborative works by sharing a virtual reality 3D space among users at remote places. In addition, it would be more useful if we could use virtual 3D annotations during collaborative work. In this paper, therefore, we construct a HybridP2P-based CVE in which a wireless handheld PDA is used for making 3D annotations and changing some visualization parameters when necessary.

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This paper compares and scrutinizes the characteristics of radiation element method by ray emission model (REM²) and discrete ordinates interpolation method (DOIM). A three-dimensional radiative heat transfer problem is solved within a rectangular enclosure containing absorbing, emitting, nonscattering medium with temperatures given as a sine function. The calculation results are validated with the zonal results and the analytical solution. Generally, the calculation results agree well with the exact solution. However, when the optically thickness is much larger than unity, the zonal and REM² results overestimate the heat source strength and wall heat flux, and when it is small, DOIM results underestimate them. The reasons and remedies are carefully discussed.

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It is well known that a lean burn engine caused by stratified mixture formation has many kinds of advantages to combustion characteristics, such as higher thermal efficiency and lower CO, NOx levels than conventional homogeneous mixture combustion. Although this combustion can achieve low fuel consumption, it produces much unburned hydrocarbon and soot because of inhomogeneity of the charge mixture in the combustion chamber. Therefore, it is necessary to investigate the effect of mixture formation on combustion characteristics in order to obtain the stable lean combustion. In this paper, fundamental studies for stratified combustion were carried out using a constant volume combustion chamber. The effect of mixture formation on the combustion characteristics in the chamber was examined experimentally. In addition, the effect of turbulence on stratified charge combustion process was observed by schlieren photography. From this study, as the swirl intensity increases, (Sv)_max is rapidly enhanced and the period of combustion is shortened. We also find that the stratification degree can be quantified by using burning velocity and it was controlled by induced air pressure and turbulent intensity.

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An experimental study has been conducted to evaluate the effects of CO₂ addition on thermal behavior in oxygen-enriched hydrogen flame. Experiments were performed on flames stabilized by a co-flow swirl burner, which was mounted on top of the furnace. Several different oxidizer compositions were prepared by volumetrically replacing N₂ by CO₂. In a steady state, the total as well as radiative heat flux from the flame to the wall of furnace has been measured using a heat flux meter. Temperature distribution in furnace has been also measured and compared. By increasing CO₂ proportion in the oxidizer, the convection became to play a more significant role rather than radiation due to heat blockage effect. Overall temperature in the furnace was seen to decrease, while the total heat flux has increased.

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The effects of radiation heat transfer on the soot formation and oxidation process in laminar diffusion flames have been studied experimentally using a “radiation shield” for an ethylene flame and a laser heating technique for propylene flames. The soot volume fraction of ethylene diffusion flames was measured for two different radiation boundary conditions. One is the “radiation shield” boundary condition (AL), established by placing the flame inside a highly polished aluminum cylinder, and the other is the fully absorbing radiation boundary condition (BB), obtained with a “black body cylinder enclosure”. The soot formation and oxidation processes are enhanced under the “radiation shield” boundary condition. A second set of experiments was conducted for propylene diffusion flames around the sooting conditions. A non-sooting flame can be converted to a sooting flame when a laser light heats up a flame at a height of 7mm above the burner (HAB), where soot particles are formed. On the contrary, a sooting flame can be changed to a non-sooting flame when the flame is heated with a laser light at 13mm HAB, where soot particles are oxidized. In this study, the absorbed amounts of radiation energy, the soot volume fraction, and the increased soot temperatures were measured.

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Turbulent jet non-premixed flame under the conditions of High Temperature Air Combustion (HiCOT) was investigated. Air diluted with nitrogen was preheated up to about 1300K. Propane was injected through a fuel tube parallel to the preheated airflow. LDV measurement of turbulence, CH-PLIF for reaction zone visualization, and NOx concentration measurements in the burnt gas were performed and the relations between these characteristics were examined. Results showed that turbulence intensity generated by perforated plate installed upstream of the fuel tube was high at high-temperature airflow due to high velocity compared with that at room temperature airflow when the flow rate was controlled to keep the excess air ratio constant regardless of preheating. The reaction zone represented by the CH-PLIF images still had a thin structure even in the HiCOT condition of oxygen concentration of 8vol.%. The flow turbulence in the combustion duct played a significant role in decreasing NOx emission. Due to turbulence, flame was broken and a bubble-like flame structure was generated, especially in the lifted flame cases, implying that the burning fuel lumps flow a considerable distance in air with a low oxygen concentration and generate uniform heat release profiles in HiCOT furnaces.

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The combustion characteristics of interacting liquid droplets with internal circulation in a convective flow are numerically investigated in order to determine the burning rate correlation of interacting droplets. For the transient analysis of 2-dimensionally arranged interacting droplets, Reynolds number based on the relative velocity between the liquid droplet and surrounding gas, vertical and horizontal distances between neighboring droplets are chosen as major parameters. The time variations of flame structure and combustion characteristics as well as the burning rate during the droplet lifetime are obtained. The results reveal that the transient flame configuration and retardation of droplet internal motion for the arbitrary droplets arrangement substantially influence on the burning rate of interacting droplets. The burning rate of interacting droplets exhibits a strong dependence on Reynolds number, the horizontal and vertical distances between droplets. The correction factor of burning rate for interacting droplets based on the single droplet combustion is also suggested in terms of major parameters.

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The liquid helium pressurization method using an electric heater makes the pressurization system of a liquid propellant rocket very simple and reliable with reducing the volume and the weight of the pressurant tank. In this pressurization system, the selection of the electric heater arrangement and the heating power is critical to its performance. This paper describes how to arrange the heaters and the effect of the heating power in the liquid helium pressurant tank of the liquid propellant rocket. The experiment was performed to find the proper heater arrangement and the results are discussed. The effect of the heating power on the pressurization performance is also investigated through the experiment.

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Combustion dynamics of laminar-premixed flames is experimentally studied using a slot burner. Sound levels and CH^* chemiluminescence intensity are measured for various mixture flow velocities and equivalence ratios of propane/air mixtures. Combustion instability is observed only for fuel lean conditions. The instability frequency increases with the mixture velocity and the measured sound level increases with the equivalence ratio as well as the mixture velocity. The nature of combustion oscillation is also investigated using a high-speed CCD camera and a periodic sudden extinction at the tip of flame caused by the interaction between flame and vortex-shedding process is identified as the source of noise emission.

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A narrow band based WSGGM with a gray gas regrouping technique is proposed for nonhomogeneous and nonisothermal combustion gas mixtures. Applying the multiplication property of narrow band-average transmissivities for gas mixtures of CO₂-H₂O, the number of gray gases, required for accurate representation of the absorption characteristics by using the narrow band based WSGGM, is increased drastically. To reduce the computational loads by reducing the number of gray gases, we propose a gray gas regrouping process where the gray gases used for the WSGGM are regrouped into a specified number of groups according to the magnitudes of absorption coefficients. To evaluate the proposed WSGGM for gas mixtures, the radiative transfer problems through CO₂-H₂O gas mixtures in 1- and 3-dimensional enclosures are solved numerically by using the discrete ordinates method. The radiative heat source terms and the radiative heat fluxes obtained by using the proposed method are fairly well compared to those obtained by using the more accurate statistical narrow band model with an excellent computational efficiency.

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Coke in an iron ore sintering process is being replaced in part by powdered anthracite; less expensive fuel. In this study, influence of the different fuel characteristics on the thermal condition in the sintering bed has been investigated using a mathematical model. Numerical simulation along with experiments in a lab-scale sintering pot has been performed. The mathematical model is based on the assumption that the sintering bed can be treated as homogeneous medium, through which a reacting flow passes. Temperature distribution and flue gas composition are predicted for various kinds of solid fuel and various particle sizes of anthracite. The simulation results show that propagation of combustion zone is faster in the case of using coke than the case of using anthracite. Results also show that the reactivity of the anthracite can be improved by decreasing the size of fuel particles.

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Passive and active controls of wakes behind axisymmetric bluff-bodies are presented. The passive controls include base-bleed (slotted disks), edge-induced longitudinal vortices behind three-dimensional polygonal plates, the fineness ratio and surface protrusion. The disk wake was further actively controlled in air using actuated tabs and in water using net-zero mass actuators along the edge. The active control suppressed the helical mode of oscillation, but enhanced the closing of the reverse flow region with reduced base pressure. Unsteady velocity vector fields from the time-resolved PIV are presented and issues related to future feedback flow control for the bluff-body wake will be addressed.

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In this investigation, experimental results on combustion control systems to suppress the pressure oscillation and combustion noise were indicated using laboratory scale rigs of premixed gas turbine combustors. As for the way of controlling, two different control approaches were examined. One was a thermoacoustic approach using minute secondary flames. The control system had a simple time-delay algorithm and equipped a microphone as a sensor. The minute secondary flames as an actuator were formed with pulsing supply of the secondary fuel using a piezo valve. The other was a fluid mechanical approach using a secondary injection method. In that case, both fuel and air injections as the secondary jet from the center of nozzle were examined to clarify the control factor to reduce the pressure oscillation and NOx emissions. As the results, combustion noise caused by pressure oscillation was reduced successfully with the suppression of about 10dB by the thermoacoustic approach. Furthermore, it was found that secondary air injection was effective to suppress the NOx emissions based on thermal NO.

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This is a summary of our research on unsteady partial cavitation and ventilated partially and supercavitating flows with special emphasis on control strategies. We draw upon our experience with a variety of projects ranging from the experimental and numerical description of sheet/cloud cavitation to the control of high-speed supercavitating bodies. In addition, our numerical simulations of partially cavitating hydrofoils indicate that there is a regime where the potential exists for feedback control of gust-induced oscillations. These efforts are in the incubation stage. The purpose of this presentation is to provide our perspective on the problems and opportunities for control of cavitation and to encourage a healthy interchange of ideas at this workshop.

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This paper describes a wind tunnel experiment on aero-acoustical effect of finite surface impedance on low Mach number (Ma) flow around a circular cylinder. Modification of surface acoustical properties of source area is said to result in reduction of radiated sound pressure level. In this paper the effect of the finite impedance not only to the acoustical effect but also to the hydrodynamic effects were examined. Three boundary conditions (BC) of surface impedance were supposed: 1) rigid surface, 2) uniform and 3) optimized impedance distribution by introducing an array of micro-scale perforation with a back space. A wind tunnel experiment was conducted according to the three types of BC with three different experimental models under the Reynolds number (Re) condition from 6000 to 12000. The third condition caused reduction of the far field pressure level by 6dB at largest case compared to the first condition.

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A new mixing method for micro-liquid has been developed. In the new method, a radiation pressure of ultrasound is used to stir liquid in a vessel without any physical contact. The developed mixing device based on the method consists of a vessel containing the liquid to be mixed and two ultrasound sources (frequency: 1.6MHz) arranged outside the vessel. One of them radiates through the bottom, the other through the side wall of the vessel. The latter sound source is divided into several segments. And the fine position of the sound source corresponding to the level of liquid is adjusted by selecting the appropriate segments. The mixing performance is evaluated according to the difference between the two local transmissibilities of laser beam in the liquid. As a result, we confirmed that by using the mixing device, the liquid (80-160µL of water and dye) become homogeneous within 1.0sec.

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