Design Considerations for Propellers in a Cavitating Environment

1978 ◽  
Vol 15 (02) ◽  
pp. 144-178 ◽  
Author(s):  
Donald L. Blount ◽  
David L. Fox
Keyword(s):  
Rational Design ◽  
Computation Time ◽  
Design Practice ◽  
Good Balance ◽  
Design Considerations ◽  
Performance Predictions ◽  
Blade Section ◽  
Selection For ◽  
Thrust And Torque ◽  
Propeller Thrust

Cavitation adds a dimension to propeller operation that necessitates rational design practice to approach a good balance of craft requirements. This paper discusses propeller characteristic format to reduce the computation time to make performance predictions and propeller selection for partially and fully cavitating conditions. In addition, maximum propeller thrust and torque loading limits are defined for four different blade section shapes, including recommended design limits. Discussers Jim W. Bordeaux Mark Oaks

METHODOLOGIES TO PREDICT HYDRODYNAMIC CHARACTERISTICS OF PUSHER AND PULLER PODDED PROPULSORS IN OBLIQUE FLOWS

2021 ◽  
Vol 158 (A4) ◽  
Author(s):  
M F Islam ◽  
F Jahra
Keyword(s):  
Computation Time ◽  
Performance Characteristics ◽  
Three Dimensions ◽  
Hydrodynamic Characteristics ◽  
Loading Conditions ◽  
Time Step ◽  
Podded Propulsor ◽  
Multiple Loading ◽  
Thrust And Torque ◽  
Straight Ahead

This paper presents the outcome of a numerical simulation based research program to evaluate the propulsive characteristics of puller and pusher podded propulsors in a straight course and at static azimuthing conditions while operating in open water. Methodologies to predict the propeller thrust and torque, and pod forces and moments in three dimensions using a Reynolds-Averaged Navier Stokes (RANS) solver at multiple azimuthing conditions and pod configurations are presented. To obtain insight into the reliability and accuracy of the results, grid and time step dependency studies are conducted for a podded propulsor in straight-ahead condition. The simulation techniques and results are first validated against measurements of a bare propeller and a podded propulsor in straight ahead condition for multiple loading scenarios and in both puller and pusher configurations. Next, simulations were carried out to model the podded propulsors in the two configurations at multiple loading conditions and at various azimuthing angles from +30° to –30° in 15° increments. The majority of the simulations are carried out using both steady state and unsteady state conditions, primarily to evaluate the effect of setup conditions on the computation time and prediction accuracy. The predicted performance characteristics of the pod unit using the unsteady RANS method were within 1% to 5% of the corresponding experimental measurements for all the loading conditions, azimuthing angles and pod configurations studied. The non-linear behaviour of the performance coefficients of the pod unit are well captured at various loading and azimuthing conditions in the predicted results. This study demonstrates that the RANS solver, with proper meshing arrangement, boundary conditions and setup techniques can predict the performance characteristics of the podded propulsor in multiple azimuthing angles, pod configurations and in the various loading conditions with a same level of accuracy as experimental results. Additionally, the velocity and pressure distributions on and around the pod-strut- propeller bodies are discussed as derived from the RANS predictions.

Rational design and latest advances of polysaccharide-based hydrogels for wound healing

2020 ◽  
Vol 8 (8) ◽  
pp. 2084-2101 ◽  
Author(s):  
Hao Hu ◽  
Fu-Jian Xu
Keyword(s):  
Wound Healing ◽  
Rational Design ◽  
Wound Dressings ◽  
Design Considerations ◽  
Current State

This review presented the crucial design considerations and current state of polysaccharide-based hydrogels as wound dressings. The commonly used crosslinking techniques are also discussed in detail.

scholarly journals Appropriate Feature Set and Window Parameters Selection for Efficient Motion Intent Characterization towards Intelligently Smart EMG-PR System

Symmetry ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1710
Author(s):  
Mojisola Grace Asogbon ◽  
Oluwarotimi Williams Samuel ◽  
Yanbing Jiang ◽  
Lin Wang ◽  
Yanjuan Geng ◽  
...  
Keyword(s):  
Additive Noise ◽  
Computation Time ◽  
Interaction Effects ◽  
Optimal Parameters ◽  
Multiple Features ◽  
Dynamic Factors ◽  
Trade Offs ◽  
Parameters Selection ◽  
Neural Information ◽  
Selection For

The constantly rising number of limb stroke survivors and amputees has motivated the development of intelligent prosthetic/rehabilitation devices for their arm function restoration. The device often integrates a pattern recognition (PR) algorithm that decodes amputees’ limb movement intent from electromyogram (EMG) signals, characterized by neural information and symmetric distribution. However, the control performance of the prostheses mostly rely on the interrelations among multiple dynamic factors of feature set, windowing parameters, and signal conditioning that have rarely been jointly investigated to date. This study systematically investigated the interaction effects of these dynamic factors on the performance of EMG-PR system towards constructing optimal parameters for accurately robust movement intent decoding in the context of prosthetic control. In this regard, the interaction effects of various features across window lengths (50 ms~300 ms), increments (50 ms~125 ms), robustness to external interferences and sensor channels (2 ch~6 ch), were examined using EMG signals obtained from twelve subjects through a symmetrical movement elicitation protocol. Compared to single features, multiple features consistently achieved minimum decoding error below 10% across optimal windowing parameters of 250 ms/100 ms. Also, the multiple features showed high robustness to additive noise with obvious trade-offs between accuracy and computation time. Consequently, our findings may provide proper insight for appropriate parameter selection in the context of robust PR-based control strategy for intelligent rehabilitation device.

Design Practice for Mooring of Floating Production Systems

1991 ◽  
Vol 28 (01) ◽  
pp. 30-38
Author(s):  
C. T. Kwan
Keyword(s):  
Rational Design ◽  
Production Systems ◽  
Design Analysis ◽  
Task Group ◽  
Mooring System ◽  
Design Practice ◽  
Design Environment ◽  
Floating Structures ◽  
Future Work

A draft "API Recommended Practice for Design, Analysis, and Maintenance of Mooring for Floating Production Systems" was developed recently by the API Task Group on Mooring Design for Floating Structures. This document is closely related to API RP-2P, "Recommended Practice for the Analysis of Spread Mooring Systems for Floating Drilling Units." because both documents address mooring of floating units. However, this document is also different in many ways from API RP-2P because there are significant differences between a floating drilling mooring system and a floating production mooring system. Major differences of this document from API RP-2P are:The design environment is significantly more severe.Dynamic instead of quasistatic mooring analysis is recommended; tension limits are relaxed.Guidelines for thruster-assisted mooring are included.Fatigue analysis is required. In the course of developing the Draft RP, the API Task Group has done some fundamental work to establish a rational design practice for FPS mooring systems. This paper highlights the new design practice, presents its basis, and points out areas where future work is needed.

A Propeller Thrust and Torque Dynamometer for Wind Tunnel Models

Strain ◽  
2002 ◽  
Vol 38 (1) ◽  
pp. 3-10 ◽  
Author(s):  
A. F. Molland ◽  
S. R. Turnock
Keyword(s):  
Wind Tunnel ◽  
Thrust And Torque ◽  
Propeller Thrust

scholarly journals Design considerations and topology selection for a 120-kW IGBT converter for EV fast charging

1998 ◽  
Vol 13 (1) ◽  
pp. 169-178 ◽  
Author(s):  
N.H. Kutkut ◽  
D.M. Divan ◽  
D.W. Novotny ◽  
R.H. Marion
Keyword(s):  
Design Considerations ◽  
And Topology ◽  
Fast Charging ◽  
Selection For ◽  
Topology Selection
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