Effect of liquid droplets on turbulence in a round gaseous jet

The main objective of this investigation is to develop a two-equation turbulence model for dilute vaporizing sprays or in general for dispersed two-phase flows including the effects of phase changes. The model that accounts for the interaction between the two phases is based on rigorously derived equations for turbulence kinetic energy (K) and its dissipation rate epsilon of the carrier phase using the momentum equation of that phase. Closure is achieved by modeling the turbulent correlations, up to third order, in the equations of the mean motion, concentration of the vapor in the carrier phase, and the kinetic energy of turbulence and its dissipation rate for the carrier phase. The governing equations are presented in both the exact and the modeled formes. The governing equations are solved numerically using a finite-difference procedure to test the presented model for the flow of a turbulent axisymmetric gaseous jet laden with either evaporating liquid droplets or solid particles. The predictions include the distribution of the mean velocity, volume fractions of the different phases, concentration of the evaporated material in the carrier phase, turbulence intensity and shear stress of the carrier phase, droplet diameter distribution, and the jet spreading rate. The predictions are in good agreement with the experimental data

Effect of Liquid Droplets on Turbulence Structure in a Round Gaseous Jet

A second-order model which predicts the modulation of turbulence in jets laden with uniform size solid particles or liquid droplets is discussed. The approach followed is to start from the separate momentum and continuity equations of each phase and derive two new conservation equations. The first is for the carrier fluid's kinetic energy of turbulence and the second for the dissipation rate of that energy. Closure of the set of transport equations is achieved by modeling the turbulence correlations up to a third order. The coefficients (or constants) appearing in the modeled equations are then evaluated by comparing the predictions with LDA-measurements obtained recently in a turbulent jet laden with 200 microns solid particles. This set of constants is then used to predict the same jet flow but laden with 50 microns solid particles. The agreement with the measurement in this case is very good

Bulletproof Vests/shields Prepared From Composite Material Based On Strong Polyamide Fibers And Epoxy Resin

Fiber Reinforced Plastics (FRP) have arisen as a main class of tactual materials having high strength and light weight implemented in a large scale of different applications. This study performs a comparison between the enhanced propidines of Kevlar 49 fiber and Twaron CT 704 reinforced with epoxy resin to obtain an efficient, light weight and slim body m o r capable of resisting high speed projectiles (9 mm bullets). Reinforcing the fabrics adds extra strength to the fabrics instead of using several unreinforced fabrics which increases the weight thickness and the cost of the final product. The response of the prepared composite material based on the two different fibers was studied by using a test barrel for the penetration test. In addition. indentation test is also au lied to compare between the mechanical properties of both laminates and determine which fabric is better for life protection application. The final results showed that using the technique of reinforcing the fabrics specially Twaron is much better where the final bulletproof shield has a smaller number of layers and was found lighter by 40% than those made by Kevlar

Correlation of transonic-cone preston-tube data and skin friction

Preston-tube measurements obtained on the Arnold Engineering Development Center (AEDC) Transition Cone have been correlated with theoretical skin friction coefficients in transitional and turbulent flow. This has been done for the NASA Ames 11-Ft Transonic Wind Tunnel (11 TWT) and flight tests. The developed semi-empirical correlations of Preston-tube data have been used to derive a calibration procedure for the 11 TWT flow quality. This procedure has been applied to the corrected laminar data, and an effective freestream unit Reynolds number is defined by requiring a matching of the average Preston-tube pressure in flight and in the tunnel. This study finds that the operating Reynolds number is below the effective value required for a match in laminar Preston-tube data. The distribution of this effective Reynolds number with Mach number correlates well with the freestream noise level in this tunnel. Analyses of transitional and turbulent data, however, did not result in effective Reynolds numbers that can be correlated with background noise. This is a result of the fact that vorticity fluctuations present in transitional and turbulent boundary layers dominate Preston-tube pressure fluctuations and, therefore, mask the tunnel noise eff ects. So, in order to calibrate the effects of noise on transonic wind tunnel tests only laminar data should be used, preferably at flow conditions similar to those in flight tests. To calibrate the effects of transonic wind-tunnel noise on drag measurements, however, the Preston-tube data must be supplemented with direct measurements of skin friction

Gold Nanoparticles and Its Potential Applications in Cancer Research

2009 Spring Meeting of the NANOFANS Forum. Presented on May 1, 2009 from 11 am-2 pm in the Marcus Nanotechnology Building (Rooms 1116-1118) on the Georgia Tech campus.Cancer Nanotechnology: New Opportunities in Engineering and Medicine / Shuming Nie, Director, Center of Cancer Nanotechnology Excellence, Emory and Georgia Tech -- Magnetic Nanoparticles and Ovarian Cancer: A Potential New Direction in Therapeutic Intervention / John McDonald, Director, Ovarian Cancer Institute and Chair of the School of Biology at Georgia Tech -- Gold Nanoparticles and Its Potential Applications in Cancer Research / Mostafa El-Sayed, Director, Laser Dynamics Laboratory at the School of Chemistry & Biochemistry at Georgia Tech.Shuming Nie is the Wallace H. Coulter Distinguished Chair Professor in Biomedical Engineering at Emory University and the Georgia Institute of Technology. His research interest is broadly in biomolecular engineering and nanotechnology. John McDonald is taking an integrated systems approach to the study of cancer. This means that he views cancer not as a defect in any particular gene or protein, but as a de-regulated cellular/ inter-cellular process. Mostafa El-Sayed is the Julius Brown Chair and Regents Professor in the School of Chemistry and Biochemistry at Georgia Tech. He researches Nanoscience and also investigates how Nanoparticles can be used in Nanomedicine, Nano Catalysis, and Nanophotonics

Echocardiographic variables associated with mitral regurgitation after aortic valve replacement for aortic valve stenosis

AbstractBackgroundMitral regurgitation (MR) is frequently associated with aortic stenosis. Previous reports have shown that coexisting mitral insufficiency can regress after aortic valve replacement (AVR) while others recommend dealing with examination.AimThe study aimed to assess the severity of MR before and after aortic valve replacement for aortic stenosis and to define the determinants of its postoperative evolution.MethodsFor this purpose, 30 adult patients referred for aortic valve surgery underwent pre- and 1month postoperative transthoracic echocardiography including 2D, MM, PW, CW and color Doppler examination.ResultsPostoperative MR improved in 68.4% of the 19 patients (63.3%) who had preoperative moderate MR (p=0.002). The effect of the valve size on the postoperative MR was statistically insignificant (0.059) but was significant on regression of the mass (p=0.001) and drop in mean PG (p=0.04) across AV. Patients with persistent moderate MR after surgery were all in AF and had significantly larger left atrial size (45±26mm), compared to none and a smaller left atrial (37±19mm) in patients in whom MR regressed or disappeared after surgery; respectively, p<0.05. The postoperative variables associated with moderate MR were peak PG across AV (29.4±5.1 vs 38.0±5.7 p=0.004), mean PG (15.04±4.4 vs 22.8±5.8 p=0.009) and LVMI (124.7±19.3 vs 147.2±31.6 p=0.065).ConclusionPreoperative predictors of residual postoperative MR were large LA and AF while the postoperative variables were high peak and mean pressure gradient across the aortic valve and high LVMI