Application of higher harmonic blade feathering on the OH-6A helicopter for vibration reduction

The design, implementation, and flight test results of higher harmonic blade feathering for vibration reduction on the OH-6A helicopter are described. The higher harmonic control (HHC) system superimposes fourth harmonic inputs upon the stationary swashplate. These inputs are transformed into 3P, 4P and 5P blade feathering angles. This results in modified blade loads and reduced fuselage vibrations. The primary elements of this adaptive vibration suppression system are: (1) acceleration transducers sensing the vibratory response of the fuselage; (2) a higher harmonic blade pitch actuator system; (3) a flightworthy microcomputer, incorporating the algorithm for reducing vibrations, and (4) a signal conditioning system, interfacing between the sensors, the microcomputer and the HHC actuators. The program consisted of three distinct phases. First, the HHC system was designed and implemented on the MDHC OH-6A helicopter. Then, the open loop, or manual controlled, flight tests were performed, and finally, the closed loop adaptive control system was tested. In 1983, one portion of the closed loop testing was performed, and in 1984, additional closed loop tests were conducted with improved software. With the HHC system engaged, the 4P pilot seat vibration levels were significantly lower than the baseline ON-6A levels. Moreover, the system did not adversely affect blade loads or helicopter performance. In conclusion, this successful proof of concept project demonstrated HHC to be a viable vibration suppression mechanism

Conceptual design for the Space Station Freedom fluid physics/dynamics facility

A study team at NASA's Lewis Research Center has been working on a definition study and conceptual design for a fluid physics and dynamics science facility that will be located in the Space Station Freedom's baseline U.S. Laboratory module. This modular, user-friendly facility, called the Fluid Physics/Dynamics Facility, will be available for use by industry, academic, and government research communities in the late 1990's. The Facility will support research experiments dealing with the study of fluid physics and dynamics phenomena. Because of the lack of gravity-induced convection, research into the mechanisms of fluids in the absence of gravity will help to provide a better understanding of the fundamentals of fluid processes. This document has been prepared as a final version of the handout for reviewers at the Fluid Physics/Dynamics Facility Assessment Workshop held at Lewis on January 24 and 25, 1990. It covers the background, current status, and future activities of the Lewis Project Study Team effort. It is a revised and updated version of a document entitled 'Status Report on the Conceptual Design for the Space Station Fluid Physics/Dynamics Facility', dated January 1990

A molten salt test loop for component and instrumentation testing

Molten salt is an effective coolant for a wide range of applications, including nuclear reactors, concentrated solar power, and other high temperature industrial heat transfer processes. The technical readiness level of components and instrumentation for high-temperature molten salt applications needs improvement for molten salt to be more widely adopted. A molten salt test loop was designed, built, and commissioned as a test bed to address these issues. The molten salt test loop at Abilene Christian University was built out of 316 stainless steel with a forced flow centrifugal-type pump, and was instrumented for remote operation. A low-temperature molten nitrate salt was used in this system, which was designed to operate at temperatures up to 300 ◦C and flow rates up to 90 liters per minute. This paper describes the loop design, computational fluid dynamics modeling, construction, and commissioning details. An outline of the data acquisition and control systems is presented. Salt samples were taken before and after introduction into the loop, and melting points were measured both before and after salt circulation. Performance of the system is discussed as well as improvements required for higher temperature loops envisioned for the future

Commisioning of the Cooling System for the Bergen Proton Computed Tomography Digital Tracking Calorimeter

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Vibration Attenuating Medical Platform

Millions of injured people are transported by ambulances each year. While the suspension systems of ambulances dampen the road vibrations felt by the passengers, they do not attenuate the vibration completely. To patients who have compromised physical states, vibration and displacement can aggravate their condition and cause additional pain. Our solution to this societal problem is the Vibration Attenuating Medical Platform (VAMP). VAMP consists of an aluminum and steel structure that is moved with a pneumatic piston. This prototype is designed to fit into existing ambulances and attenuate the vibrations not eliminated by the ambulances suspension. After conducting background research, we found that max displacement in a vehicle is 4 inches. Using a factor of safety of 1.5 we selected a 12-inch stroke length piston, with the neutral piston position at 6 inches extended. A PID control system will be used for the half scale prototype to verify system movement, while a MIMO system is planned as the final full-scale system. No testing was performed on the physical prototype, but extensive analyses were conducted on all components of the system to ensure that they would interface well once assembled

Volume 3 – Conference

We are pleased to present the conference proceedings for the 12th edition of the International Fluid Power Conference (IFK). The IFK is one of the world’s most significant scientific conferences on fluid power control technology and systems. It offers a common platform for the presentation and discussion of trends and innovations to manufacturers, users and scientists. The Chair of Fluid-Mechatronic Systems at the TU Dresden is organizing and hosting the IFK for the sixth time. Supporting hosts are the Fluid Power Association of the German Engineering Federation (VDMA), Dresdner Verein zur Förderung der Fluidtechnik e. V. (DVF) and GWT-TUD GmbH. The organization and the conference location alternates every two years between the Chair of Fluid-Mechatronic Systems in Dresden and the Institute for Fluid Power Drives and Systems in Aachen. The symposium on the first day is dedicated to presentations focused on methodology and fundamental research. The two following conference days offer a wide variety of application and technology orientated papers about the latest state of the art in fluid power. It is this combination that makes the IFK a unique and excellent forum for the exchange of academic research and industrial application experience. A simultaneously ongoing exhibition offers the possibility to get product information and to have individual talks with manufacturers. The theme of the 12th IFK is “Fluid Power – Future Technology”, covering topics that enable the development of 5G-ready, cost-efficient and demand-driven structures, as well as individual decentralized drives. Another topic is the real-time data exchange that allows the application of numerous predictive maintenance strategies, which will significantly increase the availability of fluid power systems and their elements and ensure their improved lifetime performance. We create an atmosphere for casual exchange by offering a vast frame and cultural program. This includes a get-together, a conference banquet, laboratory festivities and some physical activities such as jogging in Dresden’s old town.:Group 8: Pneumatics Group 9 | 11: Mobile applications Group 10: Special domains Group 12: Novel system architectures Group 13 | 15: Actuators & sensors Group 14: Safety & reliabilit

Interaction of Bootstrap Reservoir and Hydraulic Pump in Aircraft Hydraulic Systems

This thesis focuses on studying system- and component-level phenomena in the fighter aircraft hydraulic power supply system in detail. The objective is to find out system-level root causes for premature failures of hydraulic pumps encountered in many modern fighter aircraft, and to study phenomena related to them. The thesis establishes a theoretically justified basis for understanding the interactions of the hydraulic system, bootstrap-type reservoir and axial piston hydraulic pump. It also presents a cost-effective and flexible method for studying system- and componentlevel phenomena in an aircraft hydraulic system by combining a theoretical approach with ground and laboratory testing.The hydraulic pump and bootstrap reservoir are studied using computer simulations to find out how interactions in the system-level operation influence the internal loads of the pump. A hydraulic pump and bootstrap-type reservoir with pipework connecting them are modelled as analytical physical models. Other parts of the hydraulic system are modelled using empirical black box-type models. The models used are verified in the laboratory using a purpose-built test rig and field measurements made with a real aircraft. Root causes of failures and phenomena causing them are identified using simulations. On the basis of this, system and component design variables which affect these phenomena are determined. The results of the study prove that premature failures of the hydraulic pump encountered in certain types of high-performance fighter aircraft are related to hydraulic system design features and their service and maintenance practices. The thesis concludes with design recommendations for bootstrap-type reservoir and pump supply and drain lines

Orbiting Geophysical Observatory Attitude Control Subsystem design survey

Development history and design modifications for attitude control subsystem of OG

Development of a High-Performance Low-Weight Hydraulic Damper for Active Vibration Control of the Main Rotor on Helicopters—Part 2: Preliminary Experimental Validation

Vibrations generated by the main rotor-gearbox assembly in a helicopter are the principal cause of damage to cockpit instruments and crew discomfort in terms of cabin noise. The principal path of vibration transmission to the fuselage is through the gearbox’s rigid support struts. This article is Part 2 of a two-part paper presenting an innovative solution involving the replacement of rigid struts with low-weight, high-performance active dampers for vibration control developed by Elettronica Aster S.p.A. Part 1 provided a comprehensive overview of the system layout obtained through a model-based design process and presented a thorough description of the adopted nonlinear mathematical model. Part 2 focuses on the physical realization of the damper and its dedicated experimental test bench. The mathematical model parameter fitting procedure is presented in detail, as it has been used to help in the definition and optimization of the control schemes and the verification of the expected performance. The experimental results obtained in Part 2 not only demonstrate the compliance of the active damper prototype with the acceptance tests outlined in the ATP but also provide compelling evidence reinforcing the promise of the presented solution for effective vibration reduction