Academic literature on the topic 'Alloy-nozzle interaction'

The interaction of the SiC–SiCw–B4C–AlN system ceramic composite material (CCM) with the EP648 alloy in the process of high-temperature brazing was studied. The smallest erosion activity both in relation to CCM, and to the EP648 alloy, has HMP solder VPr50. An experimental constructionally similar sample of the nozzle assembly sector was made using uncooled nozzle blade prototypes from CCM. Tests of an experimental constructionally similar sample of the nozzle assembly sector at a temperature of 1500 °C were carried out. No traces of material ablation from the surface of the CMC were found.

A new kind of nanocomposite rare-earth magnets of Nd2Fe14B/ α-Fe were prepared by melt-spinning method. Effects of alloying element and processing parameter on the microstructure and magnetic properties of nanocomposite materials have been investigated. Zr is effective to enhance coercivity of alloys because of a refinement of grains, so that in alloy of Zr content with 1.0 at% (Zr1.0) has the smallest grain size of 17 nm and therefore causes the highest intrinsic coercivity . Addition of Zr can also enhance the ability of amorphous-forming. The combination of adding of Zr and using a smaller diameter of the nozzle in the melt-spinning method is effective for the forming of amorphous structure. According to the MFM study, the length of the magnetic contrast in the alloy is much larger than the mean grain size. The large length corresponds to that of interaction domains(ID), which is related to the exchange coupling effect.

Titanium alloys offer outstanding properties with regard to its strength to density ratio and a good corrosive resistance in air atmospheres. Substantial advancements could be made by using titanium alloys, in particular for applications in the aerospace industry and medical engineering. However, no product innovation is possible without an appropriate machining technology. For example, low thermal conductivity and hot hardness lead to limitations regarding the applicable machining parameters, particularly for continuous cutting operations. Turning of high performance materials sets high demands on machine tools and especially on the used cutting tools. For conventional continuous cutting of titanium alloys the tool life time and therefore the tool life volume is limited due to the thermal mechanical behaviour. Depending on the chemical and structural composition of the alloy, conventional cutting operations can rarely be regarded as an economic solution. The Abrasive Waterjet Turning process (AWJT) represents a promising alternative manufacturing method to produce rotation-symmetrically or helical parts made of difficult to machine materials. The AWJT process combines the kinematics of conventional turning methods with process-specific advantages of the abrasive waterjet machining. The main advantages are the high variety of machinable materials, the long life time T of the focus nozzles of at least 300 minutes and its independence of the material to be processed. Furthermore, material-inhomogeneity or the initial geometrical contour of the workpiece cannot result in tool failures. An interaction of workpiece and tool known from conventional cutting processes cannot occur. An investigation on hyper eutectic aluminium alloys has shown that AWJT is an economic manufacturing process regarding the resulted material removal rates Qw and tool life volumes. The resulting roughnesses and roundnesses are comparable to a rough turning operation. In addition, AWJT results in a lower hardness penetration depth tw in comparison to conventional turning. Machining of titanium alloys with cylindrical and external turning operations as well as grooving is the next step in the experimental investigation of the machinability of difficult to machine materials with AWJT. Therefore, the objective of the presented work is to provide a model for predicting the material removal rate, the cylindrical roundness and the surface roughness of waterjet turning of the titanium alloy Ti6Al4V. In a screening experiment the significant setting parameters were identified and an adequate range of parameter settings for the response surface study was determined. The tested parameters were the feed rate vf, the abrasive flow rate m and particle size dp, the depth of cut dc and the rotational speed n of the workpiece. It is shown that in relation to the material removal rate Qw linear main effects as well as interaction effects are significant. The developed second-order-regression-model includes these linear main and interaction effects and the quadratic effects of the relevant setting parameters. Furthermore, the achieved material removal rates, tool life volumes, cylindrical roundness and surface quality are used as target values. Additionally the changes like plastic deformations and grain damages in the rim zone were compared to conventional machined parts. Relating to the material removal rate Qw, up to 2.5 cm³/min could be achieved for AWJT at a maximum height of profile Rz below 100 microns. Furthermore, the investigation resulted in a maximum tool life volume of 750 cm³ at a given nozzle life time. The results show that AWJT can be used as an economic alternative manufacturing process for rough turning of titanium alloys.

Interacting between the next rows of the turbine creates a circumferential flow non-uniformity, which leads to origination of resonance dynamic stresses on rotor bladings with frequencies z·fn, where fn - a rotor rotation frequency, z - number of stator vanes. At projection and development of the engine is not always possible detuning from a resonance as the spectrum of eigenfrequencies of rotor blades can be wide enough in relation to a band of working rotor speed. Reduction of exterior exciting forces can be one of ways of a reduction of dynamic stresses in rotor blades. For attenuation of these forces intensity was possibly use of a stator vanes with a different spacing, and also with the blades inclined in a circumferential direction. In the given article numerical research for choice a distribution law of stator vanes spacing and a declivity angle of its blades, allowed to diminish amplitude of the unsteady air forces acting on rotor blades with frequency z·fn are presented. As object for examinations the stage of the air starter turbine, the containing 26 nozzle vanes disposed with different spacings, and 40 rotor blades without a binding has served. Rotor blades and turbine disk of the air starter are made for a single whole of an aluminium alloy. This work was executed stage by stage: in the beginning the angular disposition of vanes blades, giving maximum decrease of exciting forces on rotor blades, by results of unsteady flow calculation in the turbine was chosen; then for the found geometry of a vanes the slope angle of its blades in the circumferential direction, giving the maximum decrease of exciting forces on rotor blades was chosen. The viscous gas unsteady flow was modelled in the computational domain including all blade passages of turbine rows - 26 channels in a nozzle and 40 channels in the rotor wheel. By results of calculation dependence of decrease unsteady force acting on blades and changes of turbine efficiency from a slope angle of vanes is presented. Reduction of dynamic stresses level in rotor blades of the turbine at the expense of decrease of aerodynamic exciting forces amplitude is attained. The numerical result is confirmed experimentally in rig test by decrease of resonance stresses on explored frequencies.

In order to continue the current rate of improvements in aircraft performance, aircraft and components which are continuously optimized for all flight conditions, will be needed. Toward this goal morphing-capable, adaptive structures based on shape memory alloy (SMA) technology that enable component and system-level optimization at multiple flight conditions are being developed. This paper reviews five large-scale SMA based technology programs initiated by The Boeing Company. The SAMPSON smart inlet program showed that fully integrated SMA wire bundles could provide a fighter aircraft with a variable engine inlet capability. The reconfigurable rotor blade program demonstrated the ability of highly robust, controlled 55-Nitinol tube actuators to twist a rotor blade in a spin stand test to optimize rotor aerodynamic characteristics. The variable geometry chevron (VGC) program, which was the first use of 60-Nitinol for a major aerospace application, included a flight test and static engine test of the GE90-115B engine fitted with controlled morphing chevrons that reduced noise and increased engine efficiency. The deployable rotor tab employed tube actuators to deploy and retract small fences capable of significantly reducing blade-vortex interaction generated noise on a rotorcraft. Most recently, the variable geometry fan nozzle program has built on the VGC technology to demonstrate improved jet engine performance. Continued maturation of SMA technology is needed in order to develop innovative applications and support their commercialization.

This thesis is deals with the suitability of Ag-Sn-Sb alloy for extrusion and selection of suitable materiál for the extruder nozzle. The theoretical part of this thesis deals with the general possibilities of 3D metal printing, especially the metal printing in the semi-solid phase and with it‘s problems. The experimental part describes the development of semi-solid alloys testing device and the research od the alloy and its interactions with solid materials in mutual motion. Analyzis of mechanical and chemical influence between alloy and solid material were performed by visual investigation and analysis of elements by EDS detector. The results of these analyzes led to the choise of nozzle material suitable for extrusion of Ag-Sn-Sb alloy.

Primary water stress corrosion cracking (PWSCC) is an issue of concern in the dissimilar metal welds (DMW) connecting vessel nozzles and stainless steel piping in PWR nuclear power plants. PWSCC occurs due to the synergistic interaction of several factors including tensile weld residual stresses, a corrosion sensitive weld metal (usually Alloy 82/182 weld metal) and a corrosive environment. Several mechanical mitigation methods to control PWSCC have been developed in order to alter the weld residual stresses on the nozzle. These methods consist of applying a weld overlay repair (WOR), using a method called mechanical stress improvement process (MSIP), and applying an inlay to the nozzle ID, the latter of which is the subject of this paper. An inlay consists of machining the pipe ID at the region of the DMW and applying a PWSCC resistant weld material at the machined region. The PWSCC resistant material is mainly Alloy 52/152, which has a higher chromium content compared with Alloy 82/182. The inlay is a corrosion resistant material, and the proposed application thickness (after final machining) is 3 mm. Therefore, once the crack grows through the inlay, the growth in the underlying A82/182 material is much faster. This leads to a complicated crack shape which is small at the nozzle ID and becomes larger in the original weld material and approaches a balloon shape. Here the weld residual stress state caused by the inlay is first discussed. Next, the effect of crack growth through the inlay and into the underlying Alloy 82/182 material is discussed. Finally, implications of inlay for mitigation and consideration of alternatives is discussed.

In order to clarify the mechanism of thermal fragmentation of a molten jet dropped into a sodium pool at instantaneous contact interface temperatures below its freezing point, a basic experiment was carried out using molten copper and sodium. Copper was melted in a crucible with an electrical heater and was dropped through a short nozzle into a sodium pool, in the form of a jet column. Thermal fragmentation originating inside the molten copper jet with a solid crust was clearly observed in all runs. It is verified that a small quantity of sodium, which is locally entrained inside the molten jet due to the organized motion between the molten jet and sodium, is vaporized by the sensible heat and the latent heat of molten copper, and the high internal pressure causes the molten jet with a solid crust to fragment. It is also concluded that the thermal fragmentation is more dominant than the hydrodynamic fragmentation, in the present range of Weber number and superheating of molten jet. Furthermore, it can be explained that the thermal fragmentation caused by the molten copper jet - sodium interaction is severer than that caused by the molten uranium alloy jet - sodium interaction, which was reported by Gabor et al., because the latent heat and the thermal diffusivity of molten copper, which are the physical properties that dominate the degree of fragmentation, are much higher than those of molten uranium alloy jets.

In the Safety analysis of Fast Breeder Reactor, assessment of Molten Fuel Coolant Interaction (MFCI) assumes importance for two aspects, namely the characterization of the debris and severity of pressure pulses generation. An attempt has been made to investigate the debris generation characteristics with molten Woods Metal (Alloy of Bi 50% Pb 25% Sn 12.5% & Cd 12.5% & melting point of 346 K) - Water simulant system. Liquid Woods metal and liquid Uranium dioxide physical properties (Density, Surface tension & Kinematic viscosity) are similar. Experimental studies were conducted for various melt temperatures covering non-boiling, convective boiling and film boiling regimes of water, to assess the debris generation resulting from both hydrodynamic and thermal interaction. Woods metal was heated to the desired temperature and poured through a hot funnel having a nozzle of 8 mm release diameter into a water column of height up to 140 cm. Experiments were repeated for different coolant temperature and melt inventory up to 5 kg. The melt entry velocity was determined from video recordings. The debris is analyzed on the basis of interface temperature, Rayleigh-Taylor and Kelvin-Helmholtz instabilities. It is observed that Kelvin-Helmholtz instability is the dominant fragmentation phenomena. Contribution due to coolant boiling resulted in more debris generation in the size less than 4 mm.

The Boeing Company has a goal of creating aircraft that are capable of continuous optimization for all flight conditions. Toward this goal we have developed morphing-capable, adaptive structures based on Shape Memory Alloy (SMA) technology that enable component and system level optimization at multiple flight conditions. The SAMPSON Smart Inlet program showed that fully integrated SMA wire bundles could provide a fighter aircraft with a Variable Engine Inlet capability. The Reconfigurable Rotor Blade program demonstrated the ability of highly robust, controlled 55-Nitinol tube actuators to twist a rotor blade in a spin stand test to optimize aerodynamic characteristics. The Variable Geometry Chevrons program, which was the first use of 60-Nitinol for a major aerospace application, included a flight test and static engine test of GE90–115B engine fitted with controlled morphing chevrons that reduced noise and increased engine efficiency. The Deployable Rotor Tab employed tube actuators to deploy and retract small fences which are capable of significantly reducing blade vortex interaction generated noise on a rotorcraft. Most recently, the Variable Geometry Fan Nozzle program has built on the VGC technology to demonstrate improved jet engine performance. The Boeing Company continues to mature SMA technology in order to develop innovative applications and support their commercialization.

A single stage cryogenic liquid turbine is designed for a large-scale internal compression air-separation unit to replace the Joule-Thompson valve and recover energy from the liquefied air during throttling process. It includes a 3-dimensional impeller, variable geometry nozzle, and asymmetrical volute. Strength evaluation of such a liquid turbine is both essential and complicated, which involves a proper evaluation of stress acting on the components and mechanical property of the chosen materials at low temperature. For metals under low temperatures, brittle fracture of the metal may occur prior to fatigue damage. A comprehensive consideration of low-temperature mechanical properties of materials and mechanical loads (due to hydrodynamic force and centrifugal force) acting on the components is of particular importance. Aluminum alloy 2031 is used for the turbine impeller and its mechanical properties under low temperatures are analyzed. To evaluate the stress acting on the components, numerical investigation using 3-D incompressible Navier-Stokes Equation together with k-epsilon turbulence model and mixing plane approach at rotator-stator interface are carried out at design and off-design flow with different nozzle-vane settings. The obtained pressure force is transformed into hydrodynamic load acting on the solid surface by means of fluid-solid interaction technology, and then used in the FEM (Finite Element Method) structure analysis together with the centrifugal force. Stress distribution of the component is obtained and deformation of the component analyzed. Evaluation of impeller strength is conducted for the cryogenic liquid turbine by combining the foregoing two aspects, and a use of alloy 2031 for the turbine expander is validated.

The metallurgical characteristics of the damage observed in both service and laboratory test samples indicate that creep rupture is the dominant failure mode for Dissimilar Metal Welds (DMW) in some high temperature service conditions. However, it has also been observed that temperature cycling contributes significantly to damage and can cause failure even when primary stress levels are relatively low. Therefore, a creep-fatigue assessment procedure is required as part of a remaining life calculation. API 579-1/ASME FFS-1 2007 Fitness-For-Service standard includes a compendium of consensus methods for reliable assessment of the structural integrity of equipment containing identified flaws or damage. Part 10 of this document includes a method for protection against failure from creep-fatigue. In the assessment of DMW, a creep-fatigue interaction equation is provided to evaluate damage caused by thermal mismatch, sustained primary stresses, and cyclic secondary loads. In this work, alternative methods based on the ductility exhaustion with creep-fatigue interaction R5 V2/3 and R5 V6 are compared to the API 579-1/ASME FFS-1 standard method. The validity of an elastic FEA with linear material behavior is evaluated based on comparing results from FEA with nonlinear material behavior. A 2.25Cr 1Mo to SS 347 dissimilar joint welded with alloy 625 in a hydroprocessing heat exchanger nozzle joint was selected for the analysis. A Finite Element (FEA) model is used to estimate the sustained and cyclic primary and secondary stresses and strains for this weld. The model includes details of the geometry, material properties, boundary conditions, and loads. The results from the FEA are post-processed using the fatigue methods described above. Lastly, a sensitivity study based on operating temperature is performed. The results of this work indicate that the predictions of the number of cycles and time in service to crack initiation and creep failure are not significantly different between various methods. However, the results of the R5 V2/3 method using linear elastic FEA become invalid at higher temperatures because of significant stress redistribution. The temperature sensitivity analysis clearly showed that the life of the weld is strongly influenced by the service temperature for this type of joint.

For the safety design of a Fast Breeder Reactor (FBR), if a Core Disruptive Accident (CDA) occurred hypothetically, it is required to suppress the rapid energy release due to a prompt criticality. Even if the rapid energy release does not occur, there is a possibility that a large amount of fuel melts. Therefore it is important to achieve Post Accident Heat Removal (PAHR). In order to achieve PAHR, it is strongly required that the molten material which is released from a core region gets cool and solidifies in the sodium coolant in a reactor vessel by breaking up. It is considered that the molten fuel is injected into the coolant like a jet. Furthermore, in the actual FBR, the interfacial temperature between the molten fuel jet and the coolant is considered to be lower than the melting point of the molten material. Thus for PAHR in CDA, it is important to understand the interaction between the jet and the coolant in such a condition and to estimate the molten jet behavior quantitatively. In order to estimate quantitatively the effects of the solidification on the molten jet behavior, we carried out the experiment in which a simulant material was injected into a simulant coolant. In the experiment, we used low melting point alloy (Bi -Sn) and water as the simulant molten material and the simulant coolant respectively. In the experiments, we chose the temperature range including the condition that the interfacial temperature was lower than the melting point of the molten material. The jet breakup and the fragmentation behavior of the molten material jet were observed with a high speed video camera. Then the jet breakup length is estimated form the results. We changed the initial interfacial temperature condition by adjusting temperature of the molten material and the coolant. We also changed the jet velocity by adjusting the height of the nozzle tip from the water surface. From the experiment, we found that the jet breakup behavior depends greatly on the interfacial temperature and the injection velocity and that the solidification of a molten material jet and the growth of unstable jet surface, which results from the relative velocity of the jet to the coolant, are in a competitive relation for the jet breakup. We also found that when the molten material jet breaks up into fragments, the breakup length is independent of the initial interfacial temperature and the initial injection velocity.