Axial Lift Research Articles

Analysis of Thrust & Torque B-Series Propeller using CFD: Variation of Blade and nProp

T he propeller is an important part of determining the ship's maneuverability. The propeller itself is a tool to produce thrust that comes from engine power which is transmitted through the shaft . At their defined radial position, Propeller thrust (N) and torque (Nm) are formed from propeller blade foil sections at the local lift and drag. Particularly, the total propeller thrust will be integrated into an axial lift vector for the sections from root to tip . The selection of a good propulsion device will affect the force of the ship. One way to choose the propulsion of the ship is the selection the type of propeller and the provision of new propeller variations to produce maximum thrust. For that reason, this study aims to analyze of thrust and torque of B-series propellers using CFD by varying the number of blades: 3, 4, and 5 blades; and the propeller speed (nProp) i.e., 325, 525, and 725 rpm. The numerical analysis using computational fluid dynamics (CFD) was conducted to identify the thrust (N) and force (Nm) of the propeller. The CFD simulation consists of three main steps: pre-processor, solver manager, and post-processor. The results show that the thrust and torque significantly increased at the higher number of blades and nProp.

A Passive Permanent Magnetic Bearing With Increased Axial Lift Relative to Radial Stiffness

Four different magnet bearing configurations, with varying number of combined radially and axially magnetized rings, are studied both experimentally and using the modeling framework MagTense. First, the optimal vertical position of the radially magnetized ring is determined using the numerical model. Then, the model is validated using experimental data. Finally, we show that a bearing where the rotor and the stator each consist of a single ring of axially magnetized magnets and a single ring of radially magnetized magnets has the smallest radial force per axial lift force at an axial air gap of 1 mm. For this bearing, the ratio of the radial force per axial lift here is 0.383 times that of the same bearing without the radially magnetized ring.

Influences of the Flow Cut and Axial Lift of the Impeller on the Aerodynamic Performance of a Transonic Centrifugal Compressor

In this study, the influences of the flow cut and axial lift of the impeller on the aerodynamic performance of a transonic centrifugal compressor were analyzed. The flow cut is a method to reduce the flow rate by decreasing the impeller passage height. The axial lift is a method of increasing the impeller passage height in the axial direction, which increases the impeller exit width (B2) and increases the total pressure. A NASA CC3 transonic centrifugal compressor with a backswept angle was used as a base compressor. After applying the flow cut, the total pressure at the target flow rate was lower than the total pressure at the design point due to the increase in the relative velocity at the impeller exit. After applying the axial lift, the total pressure at the design flow rate was increased, which was caused by the reduction in the relative velocity as the passage area at the impeller exit was increased. By applying the flow cut and axial lift methods, it was shown that the variation in relative velocity at the impeller exit has a significant effect on the variation in total pressure. In addition, it was found that the relative velocity at the impeller exit of the target flow rate is maintained similar to the base impeller when the flow cut and the axial lift are combined. Therefore, by combining the flow cut and the axial lift, three transonic centrifugal impellers with flow fractions of 0.7, 0.8, and 0.9 compared to the design flow rate were newly designed.

Calculation of BWR Shroud Head Loads and Axial Lift during a Main Steam-Line Break

Core shroud cracking has been observed in several boiling water reactors (BWRs) since 1993. A current U.S. Nuclear Regulatory Commission concern is the response of a cracked core shroud to loads resulting from the main steam-line-break loss-of-coolant accident (MSLOCA). Core shroud loads and responses have been calculated by GPU Nuclear Corporation (GPUNC) for the Oyster Creek BWR/2 using the RELAP5 computer code. The objectives of the RETRAN-02 analysis performed by S. Levy Incorporated were to assess the capability of RETRAN-02 to simulate an MSLOCA and to obtain an independent validation of the GPUNC results.A main steam-line break will result in rapid depressurization of the steam dome and an upward pressure load over the shroud head. This upward force has the potential to cause separation and displacement of the shroud head if the shroud head contains a 360-deg through-wall flaw.The key parameters and phenomena affecting the core shroud head pressure differential following the initiation of the MSLOCA are critical flow through the vessel side of the steam-line break; pressure wave dynamics in the steam lines; depressurization rate of the vessel steam dome; flow inertia and pressure drop of the steam dryers, steam separators, and standpipes; and flashing of saturated liquid in the upper plenum and reactor core.The key parameters and phenomena affecting the core shroud head lift are the core shroud head mass above the cracked weld, the core shroud head projected area, and the characteristics of the shroud weld crack leakage flow path from the core bypass to the vessel downcomer annulus.Comparison of RELAP5 and RETRAN-02 calculation results shows good agreement for the transient core shroud head pressure drop and lift predictions by the two methods. An important element in simulating this rapid transient, for both RELAP5 and RETRAN-02, is the ability to calculate the shroud head loading and lift through the use of control block elements and to directly couple the effect of flow through the shroud weld crack leakage flow path to the upper plenum thermal hydraulics.

Cement spacing for the one-step post-core and crown. A new laboratory technique.

A technique to provide cement spacing for cast post-cores prior to construction of their crowns is described. The axial lift of crowns cemented with zinc phosphate was greater, but not significantly, for crowns constructed on non-spaced post-cores compared with crowns constructed on spaced post-cores. Three materials were evaluated to determine their effectiveness in providing cement spacing for post-cores. The phenomenon of post-core 'wedging' during luting was identified.