Some Experimental Results of Tests of a Low-Speed, Waterjet Propulsion System

1967 ◽  
Vol 1 (2) ◽  
pp. 97-101 ◽  
Author(s):  
MARTIN DELAO
Keyword(s):  
Propulsion System ◽  
Experimental Results ◽  
Low Speed

Design of a Multijet Omnidirectional Propulsion System for Small Jet-Boats

2010 ◽  
Vol 132 (11) ◽  
Author(s):  
David Foley ◽  
Jean-Sebastien Plante
Keyword(s):  
High Speed ◽  
Flow Model ◽  
Open Loop ◽  
Propulsion System ◽  
Experimental Results ◽  
Control Algorithms ◽  
Control Laws ◽  
Low Speed ◽  
Advanced Control ◽  
Design Requirements

Jet-boats perform remarkably well at high-speed but lack low speed maneuverability for tight maneuvers such as docking. This paper presents a joystick controlled omnidirectional propulsion system for jet-boats. The concept uses a set of fixed jet nozzles disposed around the hull. When a force is commanded by the joystick, valves on each nozzle modulate the flow so that the sum of nozzle thrusts correspond to the commanded force. The positions and angles of the nozzles are optimized with an index of omnidirectionality quality based on the projection of a set of force solutions on a shell with the shape of a desired force space. The choice of valve positions and engine speeds is done by the numerical inversion of an internal viscous flow model. A 3D simulator, backed by experimental results, serves to (1) evaluate the ability of the proposed concept in meeting its design requirements and (2) develop control algorithms. Experimental results show that the proposed omnidirectional system is effective for low speed maneuverability with open-loop force control. The present work also offers an effective omnidirectional propulsion system that is easy to enhance with advanced control laws. Velocity feedback control is given as an example and shows important improvement of maneuverability and robustness to miscalibration.

Modelling the Axial-Flow Compressors for Calculating Starting of Turbojet Engines

1985 ◽  
Author(s):  
Yan De-You
Keyword(s):  
Excellent Agreement ◽  
Axial Flow ◽  
Structural Formula ◽  
Experimental Results ◽  
Low Speed ◽  
Structural Formulae ◽  
Axial Flow Compressors

This paper provides a method of modelling the axial-flow compressors in the low speed starting regime of an engine from windmilling to idling. A structural formula for the model is established by means of reference (1). A method of step-by-step regression is provided by the author for determining the coefficient matrices of the structural formulae. Excellent agreement was obtained between the computational and experimental results.

A Biomimetic Jellyfish-Inspired Jet Propulsion System Using an Iris Mechanism

2012 ◽  
Author(s):  
Kenneth Marut ◽  
Colin Stewart ◽  
Alex Villanueva ◽  
Dragan Avirovik ◽  
Shashank Priya
Keyword(s):  
Power Consumption ◽  
Test Stand ◽  
Propulsion System ◽  
Experimental Results ◽  
Jet Propulsion ◽  
Iris Diaphragm ◽  
Propulsion Mechanism ◽  
Vehicle Efficiency ◽  
Maximum Thrust

A bio-inspired jet propulsion mechanism was designed and developed for development of proficient unmanned undersea vehicles (UUVs). The propulsion mechanism mimics that of the Sarsia sp. jellyfish which measures approximately 1 cm in diameter. In order to achieve a biomimetic uniform bell contraction, an electrical motor was used in conjunction with a novel circumferential actuator based upon a mechanical iris diaphragm. This mechanism allows actuation of a deformable cavity. The current prototype was scaled to a diameter 10 times larger than Sarsia measuring 10 cm in diameter. The performance of the propulsion mechanism was analyzed both experimentally theoretically. The prototype was mounted on a test stand which allowed for measurement of thrust and power consumption. Analytical and experimental results were compared to that of the performance of Sarsia. It was found that the overall mechanism created a maximum thrust of 5.1 N with a calculated vehicle efficiency of 0.17% and proficiency of 4.8 s−1.

Rigid Mode Vibration Control and Dynamic Behavior of Hybrid Foil–Magnetic Bearing Turbo Blower

2016 ◽  
Vol 139 (5) ◽  
Author(s):  
Sena Jeong ◽  
Doyoung Jeon ◽  
Yong Bok Lee
Keyword(s):  
Vibration Control ◽  
Dynamic Pressure ◽  
Magnetic Bearing ◽  
Experimental Results ◽  
Low Speed ◽  
Vibration Stability ◽  
Turbo Blower ◽  
Foil Bearing ◽  
Vibration Responses ◽  
Aerodynamic Instability

In this study, experimental and analytical analyses of the vibration stability of a 225 kW class turbo blower with a hybrid foil–magnetic bearing (HFMB) were performed. First, critical speed and unbalance vibration responses were examined as part of the rotordynamic research. Its shaft diameter was 71.5 mm, its total length was 693 mm, and the weight of the rotor was 17.8 kg. The air foil bearing (AFB) utilized was 50 mm long and had a 0.7 aspect ratio. In the experiments conducted, excessive vibration and rotor motion instability occurred in the range 12,000–15,000 rpm, which resulted from insufficient dynamic pressure caused by the length of the foil bearing being too short. Consequently, as the rotor speed increased, excessive rotor motion attributable to aerodynamic and bearing instability became evident. This study therefore focused on improving rotordynamic performance by rectifying rigid mode unstable vibration at low speed, 20,000 rpm, and asynchronous vibration due to aerodynamic instability by using HFMB with vibration control. The experimental results obtained were compared for each bearing type (AFB and HFMB) to improve the performance of the vibration in the low-speed region. The experimental results show that the HFMB technology results in superior vibration stability for unbalance vibration and aerodynamic instability in the range 12,000–15,000 rpm (200–250 Hz). The remarkable vibration reduction achieved from vibration control of the HFMB–rotor system shows that oil-free turbomachinery can achieve excellent performance.

Magnetic Suspension for Low-Speed Vehicles

1978 ◽  
Vol 100 (4) ◽  
pp. 333-342 ◽  
Author(s):  
P. K. Sinha
Keyword(s):  
High Reliability ◽  
Suspension System ◽  
Urban Transport ◽  
Magnetic Suspension ◽  
Experimental Results ◽  
Performance Criteria ◽  
Transport Systems ◽  
Vehicle Suspension ◽  
Low Speed ◽  
Capital Costs

Several forms of novel suspension systems for passenger-carrying vehicles are currently being investigated throughout the world. Most of these, however, are aimed at high-speed, intercity transport systems, and comparatively less development work has been undertaken to provide a new form of low-speed system for urban-transportation. The possibility of using controlled direct-current electromagnets for low-speed (up to 70 kph) vehicle suspension has been explored in this paper. This system, also known as ferromagnetic or attraction suspension system, offers a very attractive combination of design simplicity, low operating and maintenance costs, high reliability and virtually silent operation. This system is also considered to have capital costs comparable with alternative forms of urban-transport systems and could be designed to fit into the existing fabric of cities and towns. The feasibility of the d-c system is illustrated here through analytical and experimental results of the ride and track-clearance characteristics for a single-degree of freedom suspension system. These results are used to formulate a procedure for designing a multimagnet vehicle suspension system. Main design and performance criteria for maglev vehicles are discussed in the context of experimental results obtained from test vehicles. Engineering aspects of some of the system components have been presented with a view to evaluating their suitability for low-speed systems.

scholarly journals General Purpose Frigate Low-Speed Electric Drive - When does it Make Sense?

2018 ◽  
Author(s):  
S M Newman ◽  
O J Simmonds
Keyword(s):  
Electric Drive ◽  
General Purpose ◽  
Propulsion System ◽  
Electrical Machines ◽  
Hybrid Propulsion ◽  
Low Speed ◽  
Reasonable Amount ◽  
Number Of Factors ◽  
Hybrid Solution ◽  
The Cost

Light Frigates (LFs), like many warships, will spend a reasonable amount of sea time at low speeds. By definition, the LF has to be capable yet affordable, a difficult balance to strike, but a dichotomy which has to be addressed particularly given the cost pressures our world’s navies are under. Whilst low engine loading at loiter speeds may lead to fuel inefficiency and increased maintenance burden, a purely mechanical Combined Diesel and Diesel (CODAD) propulsion system is attractive from a simplicity perspective. Hybrid propulsion architectures, using electrical machines as motors for low-speed operations, can be employed as a way to address this part of the operating profile. This paper explores to what degree a hybrid solution is appropriate for a LF through the consideration of a number of factors.

Optimization of Non-axisymmetric Endwall Contours for the Rotor of a Low Speed, 112-Stage Research Turbine With Unshrouded Blades—Optimization and Experimental Validation

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Jonathan Bergh ◽  
Glen Snedden ◽  
Dwain Dunn
Keyword(s):  
Experimental Results ◽  
Pressure Probe ◽  
Test Case ◽  
Current Case ◽  
Low Speed ◽  
Additional Information ◽  
Measurement Plane ◽  
Direct Laser ◽  
Improved Performance ◽  
Design And Practice

Abstract This paper presents the predicted, as well as final experimental results for the design of an automatically optimized non-axisymmetric endwall and as such, attempts to close the loop between design and practice, providing additional information to other groups involved in the design of endwall contours. The contours designed in this investigation were manufactured using the direct laser sintering rapid prototyping method and installed and tested in the low-speed, 112-stage turbine at the CSIR’s test turbine facility (TTF) in Pretoria, South Africa. Steady-state 5-hole pressure probe traverses were used to characterize the performance and flow profiles upstream, immediately downstream and in a quasi-“mixed-out” sense downstream of the rotor. In addition to the datum (annular) case, both the computed as well as experimental results were compared to the corresponding results generated for a “generically” contoured rotor which was originally designed for a linear cascade test case, but one which used the same blade profile to the current case. The results show that in general both sets of contours performed well, although the added emphasis on flow correction for the contours produced in this investigation resulted in slightly worse performance in terms of loss at the rotor exit (X3) but greatly improved performance in terms of the efficiency and flow angles at the “mixed-out” (X4) measurement plane.

scholarly journals A 21st Century Warship With a 21st Century Propulsion System

1998 ◽  
Author(s):  
Mark Carter ◽  
Magnus Olsson ◽  
Jan-Erik Gustavson ◽  
Joe Ranero
Keyword(s):  
21St Century ◽  
Diesel Engines ◽  
High Speed ◽  
Propulsion System ◽  
Design Features ◽  
Signal Model ◽  
Turbine Engine ◽  
Low Speed

The Visby Class Corvette will enjoy the advantages of a Combined Diesel or Gas (CODOG) turbine arrangement in which the diesel engines are used for low-speed mine hunting and ASW missions, while the four turbines can be operated either individually or in pairs to provide cruise or high-speed dash capability. The integration of these features into a single gearbox, the design of the Allied Signal model TF50A turbine engine, and the integration of the CODOG system into the ship is discussed herein. Attention is focused on the unique design features which provide the “stealth” capabilities of this ship.

scholarly journals Low Speed Vertical Axis Current Turbine (LS-VACT): Experimental Results

2020 ◽  
Vol 884 ◽  
pp. 012089
Author(s):  
N Muhamat Yain ◽  
A M Abdul Malik ◽  
A Ali ◽  
A S Souf-Aljen ◽  
F Behrouzi ◽  
...  
Keyword(s):  
Vertical Axis ◽  
Experimental Results ◽  
Low Speed ◽  
Current Turbine

217 Analysis of the oblique impact system composed of ball and plate : The comparison of low-speed impact experimental results with calculated results

2009 ◽  
Vol 2009 (0) ◽  
pp. _217-1_-_217-6_
Author(s):  
Tetsuyuki HONGO ◽  
Yoshio IWATA ◽  
Hiroshi SAEGUSA ◽  
Toshihiko KOMATSUZAKI ◽  
Seiiti OHGAKU
Keyword(s):  
Oblique Impact ◽  
Experimental Results ◽  
Low Speed ◽  
Impact System
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