CFD Evaluation of a New Centrifugal Pump Concept for Rocket Propulsion

The rocket propulsion system provides forces to a flight shuttle so that it can accelerate or decelerate and overcome the drag force or change direction. The simplest propulsion system can be made using pressurized propellant tanks with supply of compressed gas but, for minimum weight design requirements, a system with propellant pumps satisfies better. This paper aims to evaluate the performances of a new centrifugal pump concept using computational fluid dynamics. The paper is based on an innovative pump design consisting of two centrifugal stages superposed into a novel and promising configuration. The CFD analysis is performed on 3D domains by using the CFD commercial code ANSYS CFX. The numerical solvers used are pressure based using the SIMPLE method with RANS. The post processing of the results delivers speed, pressure and temperature distribution in the field. A classic two stage centrifugal pump is compared with the new stage-over-stage design, where the axial length is considerably reduced. Regarding the total efficiency, in both cases its value is around 97%. This paper presents an innovative geometry for centrifugal pumps, that can contribute to the improvement of rocket propulsion systems

Mutual Funds in Romania in 2010

The purpose of this paper is to analyse the situation of mutual investment funds in Romania, in the context of the year 2010, when Romania is a member state of the European Union and in the midst of a financial crisis. In the analysis done we've used the statistical data regarding the evolution of investments in mutual funds done in Romania during the last few years. The main conclusions  are:  the  market  ratio  in  the  beginning  of  the  year  2010  is  in  favour  of  the diversified funds; certain bond funds surpassed the yields of the bank deposits, and the share funds had yields of 100% in 2009, but drew a small number of new investors

Improved electrical response in GdMnO3 doped (K, Na)NbO3 piezoelectric speaker

[(K0.368Na0.432)Li0.5][Nb0.86Sb0.04Ta0.1]O3 doped with 0.5 mol% GdMnO3 piezoelectric speakers were obtained, with good frequency sensibility in the range 20 Hz – 20 kHz. The additive used distorts the crystalline structure to a mixture of orthorhombic and tetragonal phases at room temperature. Also the dopants used shift the high temperature phase transitions toward room temperature. Good piezoelectric properties were obtained for doped samples, with an optimum piezoelectric charge constant d33 of 127 for [(K0.368Na0.432)Li0.5][Nb0.86Sb0.04Ta0.1]O3 - 0.5 mol % GdMnO3, a planar coupling coefficient of 0.39 and a quality factor of 102

OPTIMIZING LARGE COMBINATIONAL NETWORKS FOR K-LUT BASED FPGA MAPPING

Optimizing by partitioning is a central problem in VLSI design automation, addressing circuit’s manufacturability. Circuit partitioning has multiple applications in VLSI design. One of the most common is that of dividing combinational circuits (usually large ones) that will not fit on a single package among a number of packages. Partitioning is of practical importance for k-LUT based FPGA circuit implementation. In this work is presented multilevel a multi-resource partitioning algorithm for partitioning large combinational circuits in order to efficiently use existing and commercially available FPGAs packagestwo-way partitioning, multi-way partitioning, recursive partitioning, flat partitioning, critical path, cutting cones, bottom-up clusters, top-down min-cut

Morphological investigation of calcium phosphates electrodeposited on Ti in the presence of tartaric acid

The electrochemical deposition method was employed to deposit calcium phosphates on Ti substrates in the presence of different concentrations of tartaric acid. Scanning electron microscopy was used to investigate the morphology of the obtained specimens. The micrographs indicate that as the tartaric acid concentration increases, the size and number of calcium phosphate irregular structures increases as well. At the highest concentration a new morphology is evidenced, represented by flat ordered structures with high aspect ratio

Novel (K,Na)NbO3 based piezoelectric ceramic

Novel (1-x)(K0,5Na0,5)NbO3 – xGdAlO3 piezoelectric ceramics were obtained using solid state method. The phase purity was confirmed by X-ray diffraction. The unit cell parameters were refined. The results show the presence of a phase transition from orthorhombic to tetragonal