Rapid Prototyping for Aerospace Launch Vehicles

Initial studies of the aerodynamic characteristics of proposed launch vehicles can be made more accurately if lower cost, high-fidelity aerodynamic models are available for wind tunnel testing early in design phase. Rapid Prototyping (RP) is an emerging key technology for producing accurate parts directly from CAD models quickly, with little need of human intervention. Use of RP models was studied at the NASA Marshall Space Flight Center (MSFC). It was concluded that RP methods and materials can be used only for preliminary design studies and limited configurations because of the RP material properties that allow bending of models under higher loading conditions. The reported results and analysis were based on wind tunnel balances. These balances give total load on the body. Thus, there is a need for studying the pressure distribution, the wave pattern and the system behavior under high-speed conditions. In order to study the above goals, a blunt nose cone of a launch vehicle/ missile was tested which was made using the solid based RP method FDM, with a Mach number of 2.0. It is concluded that RP models can take the load at the Mach number 2.0 and also can capture the pressure distribution and wave pattern.Mechanical Engineerin

Recycling of RP Models by Solution - Casting Technique

Most of the Rapid Prototyping systems process polymeric materials for model making. Increased environmental concerns and waste minimization demands the recycle of these polymeric models. One way is to melt the models and cast it. However, in this method polymer degradation may occur leading to diminished functionality. In the present work a preliminary attempt has been made to reuse the polymer components by dissolving in a suitable solvent and casting the same into the required shape using soft tooling. Acrylonitrile Butadiene Styrene (ABS) polymer components, made by Fused Deposition Modeling (FDM) process were taken for the present studyMechanical Engineerin

Base pressure studies from over expanded nozzle for area ratio 2.56

The present paper aims at study of variations in base pressure at different levels of over expansion of jet in a suddenly expanded axi-symmetric duct. The results of an experimental investigation carried out at two different fixed levels of Over Expansion namely 0.277 and 0.56 are compared. The area ratio of the present study is 2.56. The jet Mach numbers at the entry to the suddenly expanded duct, studied are 2.2 and 2.58. The length-to-diameter ratio of the suddenly expanded duct is varied from 10 to 1. Active control in the form of four micro jets of 1mm orifice diameter located at 900 intervals along a pitch circle diameter of 1.3 times the nozzle exit diameter in the base region are employed. In addition to base pressure, wall pressure field along the duct is also studied. From the present studies it is found that at a high level of over expansion micro jets are marginally effective. It is also found from wall pressure studies that the micro jets do not disturb the flow field in the enlarged duct

Active Control of Flow through the Nozzles at Sonic Mach Number

ABSTRACT The effectiveness of micro jets to control the base pressure in suddenly expanded axi-symmetric ducts are studied experimentally. As an active control in the form of four micro jets of 1 mm orifice diameter located at 90 0 intervals along a pitch circle diameter of 1.3 times the nozzle exit diameter in the base region was employed. The Mach number of the present study is unity. The area ratio (ratio of area of suddenly expanded duct to nozzle exit area) studied are 2.56, 3.24, 4.84 and 6.25. The L/D ratio of the sudden expansion duct varies from 10 to 1. From the experimental results, it is found that the micro jets can serve as active controllers for base pressure. Further, the control effectiveness of the micro jets is getting enhanced under the influence of favourable pressure gradient. To study the effect of micro jets on the quality of flow in the enlarged duct wall pressure was measured and it is found that the micro jets do not disturb the flow field

ACTIVE CONTROL OF BASE PRESSURE IN SUDDENLY EXPANDED FLOW FOR AREA RATIO 4.84

Abstract: Airflow from convergent-divergent axi-symmetric nozzles expanded suddenly into circular duct of larger cross-sectional area than that of nozzle exit area are studied experimentally, focusing attention on the base pressure and the flow development in the enlarged duct. Micro-jets of 1 mm orifice diameter located at 90 0 intervals along a pitch circle diameter (pcd) 1.3 times the nozzle exit diameter were employed as the controller of the base pressure. The tests are conducted for Mach numbers 1.87, 2.2 and 2.58. The area ratio of the present study is 4.84. The length-to-diameter ratio of the suddenly expanded duct is varied from 10 to 1 and nozzle pressure ratio (NPR) in the range 3 to 11. It is found that the active control in the form of blowing through small orifices (micro jets) are effective in controlling the base pressure field and even do not augment the flow field in the duct. An increase of 45 percent in base pressure was achieved for certain combination of parameters of the present study

Optimization of production, biochemical characterization and In Vitro evaluation of the therapeutic potential of fibrinolytic enzymes from a new Bacillus Amyloliquefaciens

The capacity of fibrinolytic enzymes to degrade blood clots makes them of high relevance in medicine and in the pharmaceutical industry. In this work, forty-three microorganisms of the genus Bacillus were evaluated for their potential to produce fibrinolytic proteases. Thirty bacteria were confirmed as producers of fibrinolytic enzymes, the best results obtained for the strain Bacillus amyloliquefaciens UFPEDA 485. The optimization of the enzyme production conditions was done by a central composite design (CCD) star 23 that allowed to define the optimal conditions for soybean flour and glucose concentrations and agitation rate. The highest fibrinolytic activity (FA) of 813 U mL-1 and a degradation of blood clot in vitro of 62% were obtained in a medium with 2% (w/v) of soybean flour and 1% (w/v) glucose at 200 rpm after 48 h of cultivation, at pH 7.2 and 37 °C. The obtained fibrinolytic enzyme was characterized biochemically. Fibrinolytic activity was inhibited by PMSF (fluoride methylphenylsulfonyl - C7H7FO2S) 91.52% and EDTA (ethylenediaminetetraacetic acid - C10H16N2O8) 89.4%, confirming to be a serine- metallo protease. The optimum pH and temperature were 7.0 and 37 oC, respectively, and the enzyme was stable for 12 h. The fibrinolytic activity at physiological conditions of this enzyme produced by Bacillus amyloliquefaciens UFPEDA 485, as well as its long term stability, demonstrate that it has suitable characteristics for human and veterinary applications, and promises to be a powerful drug for the treatment of vascular diseases.We express our thanks to Coordination for the Improvement of Higher Level Education Personnel (CAPES) - Doctoral Sandwich Program (PDSE) Nº 0259/ 12-8 and National Council for Scientific and Technological Development (CNPq) - Nº 202026/2011-6 for the financial support