Control of plume interference effects on axisymmetric afterbodies

Plume interference effects on the axisymmetric flowfields around powered missiles are investigated using computational techniques. The study is mainly to understand the physics of the plume-induced shock and separation particularly at high plume to exit pressure ratios with and without shock-turbulent boundary layer control methods

Experimental Research on Performances of Air Turbines for a Fixed Oscillating Water Column-Type Wave Energy Converter

A fixed oscillating water column (OWC)-type wave energy converter is composed of an air chamber for primary conversion and an air turbine for secondary conversion. In the optimal design method of a fixed OWC-type wave energy converter, it is necessary to develop a design method which can consider the characteristics of incident wave motion, the motion of the internal free surface affected in the structure such as a partly submerged wall, the fluctuation of air pressure in an air chamber, the rotation of the air turbine. In this paper, the 2-dimensional wave tank tests in regular waves for the performance evaluation of the air turbines in a fixed OWC-type wave energy converter were conducted to obtain the data needed to make this design method. As the results, the effects of the impulse turbine specification such as the rotor inlet/outlet angle, the guide vane's number and the vane's setting angle on the primary and secondary conversion efficiencies are clarified experimentally. Furthermore, the performances of the Wells turbines with different number of blade are presented for comparison of the operating condition

An investigation of temperature separation phenomenon in the vortex chamber

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.The vortex chamber is a simple device with no moving parts that separates compressed gas into a high temperature region and a low temperature region. Recently, vortex chamber is being received much attention but also high industrial demand because of its structural simplicity and better performance of the temperature separation, compared with the previous vortex tubes. In the present study, both experimental and numerical analysis has been carried out to investigate the temperature separation inside a vortex chamber. Working fluid enters the chamber through four tangential inlet ports and exits through one central exit port. To investigate the temperature separation phenomenon, static pressures and temperatures at several points inside the vortex chamber were measured using highly sensitive pressure transducers and thermocouples. Data obtained from experiments was used to verify the computational results. 3-D unsteady RANS equations were considered to simulate compressible flow inside the vortex chamber. Numerical results were observed to be in good agreement with experimental ones. Many hypotheses are discussed in terms of energy transfer mechanisms and Pressure Gradient Waves (PGW) in the paper.dc201

Effect of Inlet Geometry on Fan Performance and Flow Field in a Half-Ducted Propeller Fan

In order to clarify the effect of rotor inlet geometry of half-ducted propeller fan on performance and velocity fields at rotor outlet, the experimental investigation was carried out using a hotwire anemometer. Three types of inlet geometry were tested. The first type is the one that the rotor blade tip is fully covered by a casing. The second is that the front one-third part of blade tip is opened and the rest is covered. The third is that the front two-thirds are opened and the rest is covered. Fan test and internal flow measurement at rotor outlet were conducted about three types of inlet geometry. At the internal flow measurement, a single slant hotwire probe was used and a periodical multisampling technique was adopted to obtain the three-dimensional velocity distributions. From the results of fan test, the pressure-rise characteristic drops at high flowrate region and the stall point shifts to high flowrate region, when the opened area of blade tip increases. From the results of velocity distributions at rotor outlet, the region with high axial velocity moves to radial inwards, the circumferential velocity near blade tip becomes high, and the flow field turns to radial outward, when the opened area increases

Histological evaluation of nonsurgical periodontal treatment with and without the use of sodium hypochlorite / amino acids and cross-linked hyaluronic acid gels in dogs.

OBJECTIVES To evaluate periodontal wound healing following scaling and root planing (SRP) in conjunction with the application of sodium hypochlorite/amino acids and cross-linked hyaluronic acid (xHyA) gels in dogs. MATERIALS AND METHODS In four beagle dogs, 2-wall intrabony defects were created and metal strips were placed around the teeth. Clinical parameters were measured 4 weeks after plaque accumulation. The experimental root surfaces were subjected to SRP with either the subgingival application of a sodium hypochlorite/amino acid gel and a xHyA gel (test group) or SRP alone (control group) using a split-mouth design. Clinical parameters were re-evaluated at 6 weeks. The animals were sacrificed at 8 weeks for histological analysis. RESULTS The test group showed significant improvements in all clinical parameters compared to the control group. Histologically, the test group exhibited statistically significantly greater new bone formation [i.e., length of newly formed bone, new bone area] compared with the control group (p < 0.05). Furthermore, statistically significantly greater formation of new attachment [i.e., linear length of new cementum adjacently to newly formed bone with inserting collagen fibers] and new cementum was detected in the test group compared with the control group at 8 weeks (p < 0.05 and p < 0.01, respectively). CONCLUSION The adjunctive subgingival application of sodium hypochlorite/amino acid and xHyA gels to SRP offers an innovative novel approach to enhance periodontal wound healing/regeneration. CLINICAL RELEVANCE The present findings have for the first-time shown histologic evidence for periodontal regeneration in support of this novel treatment modality

Air Turbines for Wave Energy Conversion

This paper describes the present status of the art on air turbines, which could be used for wave energy conversion. The air turbines included in the paper are as follows: Wells type turbines, impulse turbines, radial turbines, cross-flow turbine, and Savonius turbine. The overall performances of the turbines under irregular wave conditions, which typically occur in the sea, have been compared by numerical simulation and sea trial. As a result, under irregular wave conditions it is found that the running and starting characteristics of the impulse type turbines could be superior to those of the Wells turbine. Moreover, as the current challenge on turbine technology, the authors explain a twin-impulse turbine topology for wave energy conversion