نتایج جستجو برای: propeller
تعداد نتایج: 3766 فیلتر نتایج به سال:
Simulation of the flow around propeller is a complex fluid flow problem, especially when the propeller is close to free surface. In this study, the effect of different depths on the performance and efficiency of a B-Wageningen series close to surface of water have been numerically investigated. For this purpose the ANSYS-FLUENT commercial software has been used to solve the viscous, incompressi...
However, a solution does exist, whose understanding relies on the application of the classical laws of physics and which is free of contradictions: if the electron is assumed to be made up of two massless constituent particles, then this assumption correctly predicts the experimental results. It provides the correct relationship between the parameters of the electron: its mass, its constant ang...
This paper focuses on strong propeller effects in a full six degree-of-freedom (6DOF) aerodynamic modeling of small UAVs at high angles of attack and high sideslip in maneuvers performed using large control surfaces at large deflections for aircraft with high thrust-to-weight ratios. For such configurations, the flight dynamics can be dominated by relatively large propeller forces and strong pr...
In this paper, a design of counter-rotating propeller (CRP) for stratospheric airship in low Reynolds number is tested in experiment for the first time. In consideration of stratosphere environment, a two-bladed counter-rotating propeller is designed for stratospheric airship. With the similarity theory of Reynolds number and advanced ratio, the experiment is conducted in low Reynolds number wi...
OBJECTIVE The objective of this study was to evaluate the feasibility of using multishot PROPELLER for diffusion-weighted imaging (DWI) of the abdomen. MATERIALS AND METHODS Diffusion-weighted abdominal imaging was performed in 9 healthy volunteers and 3 patients using both single-shot DW-SE-EPI and multishot DW-PROPELLER (BLADE sequence). We compared ADC measurements in phantoms, liver and p...
Propeller crashback is an off-design operating condition where a propeller rotates in the reverse direction. Experiments (Bridges 2004, Tech Rep. MSSU-ASE-04-1, Department of Aerospace Engineering, Mississippi State University) have shown that the presence of an upstream hull significantly increases the side force on a propeller in crashback below an advance ratio of J = −0.7. Large-eddy simula...
Ship operators are calling more often for reduced fuel consumption and economic ship operation also in offdesign. The versatile operation profile of ship types such as RoRo-vessels are then a challenge for the design of the propeller and for the propulsion concept. This paper presents aspects on the propeller design and propulsion concept of a ship as well as design methods for the propeller. L...
Introduction Diffusion-weighted MRI (DWI) provides a non-invasive method for in vivo evaluation of tissue water mobility. Most DWI studies employ single-shot DWEPI techniques which can suffer severe artifacts and image distortion in abdominal imaging applications. Multi-shot TSE-based DW-PROPELLER [1] may overcome these limitations. DW-PROPELLER for brain [2] and abdominal [3] imaging has demon...
Today’s unmanned aerial vehicles are being utilized by numerous groups around the world for various missions. Most of the smaller vehicles that have been developed use commercially-off-the-shelf parts, and little information about the performance characteristics of the propulsion systems is available in the archival literature. In light of this, the aim of the present research was to determine ...
This paper proposes a thrust estimation scheme for marine propellers in four-quadrant operations. To calculate the thrust and torque coefficients of screw propeller in four-quadrant, a Chebyshev fit expression of the propeller properties in four-quadrant for surface vessel is given, and then it is changed into an ordinary polynomial expression. These expressions are suitable for calculating the...
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