Rotor Unit Research Articles

Control of Rotor Function in Light-Driven Molecular Motors

A study is presented on the control of rotary motion of an appending rotor unit in a light-driven molecular motor. Two new light driven molecular motors were synthesized that contain aryl groups connected to the stereogenic centers. The aryl groups behave as bidirectional free rotors in three of the four isomers of the 360° rotation cycle, but rotation of the rotors is hindered in the fourth isomer. Kinetic studies of both motor and rotor functions of the two new compounds are given, using (1)H NMR, 2D-EXSY NMR, and UV-vis spectroscopy. In addition, we present the development of a new method for introducing a range of aryl substituents at the α-carbon of precursors for molecular motors. The present study shows how the molecular system can be photochemically switched between a state of free rotor rotation and a state of hindered rotation and reveals the dynamics of coupled rotary systems.

Exhaust gas temperature measurements in diagnostic examination of naval gas turbine engines: Part II Unsteady processes

Exhaust gas temperature measurements in diagnostic examination of naval gas turbine engines: Part II Unsteady processes The second part of the article presents the results of operating diagnostic tests of a two- and three-shaft engine with a separate power turbine during the start-up and acceleration of the rotor units. Attention was paid to key importance of the correctness of operation of the automatic engine load control system, the input for which, among other signals, is the rate of increase of the exhaust gas flow temperature. The article presents sample damages of the engine flow section which resulted from disturbed functioning of this system. The unsteady operation of the compressor during engine acceleration was the source of excessive increase of the exhaust gas temperature behind the combustion chamber and partial burning of the turbine blade tips.

Ultrafast Light-Driven Nanomotors Based on an Acridane Stator

A series of molecular motors featuring a symmetrical acridane stator is reported. Photochemical and thermal isomerization experiments confirm that this stator, in combination with a thiopyran rotor, results in molecular rotary motion in which the rate-determining thermal helix inversion proceeds effectively only at temperatures above 373 K. The introduction of a cyclopentanylidene rotor unit results in a decrease in steric hindrance with respect to the stator, and as a consequence, a 10(12)-fold increase in the rate of thermal helix inversion is observed. Nanosecond transient absorption spectroscopy allows for the thermal processes to be followed accurately at ambient temperature. The rotary motor is shown to be able to operate at 0.5 MHz rotational frequencies under optimal conditions.

Methods for evaluating effective mortars and protective coatings for laying a heating unit lining

Results are provided for the effective development of procedures for determining the properties of mortars, protective coatings, and bonding elements, consisting of refractory objects and mortars for lining a rotary Waelz kiln, horizontal converters, reverbatory furnaces, and other heating units. Optimum compositions are developed for refractory adhesives, mixes and cements using effective methods for evaluating mortars and protective coatings. The use of protective coatings and mortars makes it possible to prolong the working life of units by 25–50% and thereby reduce the number of ongoing and major repairs of a unit lining and to obtain a tangible economic effect.

ヒドリンダセン-2,6-ジカルボニトリル誘導体を双極回転子として有するマクロサイクルの構築とその回転配向制御

ヒドリンダセン-2,6-ジカルボニトリル誘導体を双極回転子として有するマクロサイクルの構築とその回転配向制御

Centrifugal shaping of polymer composites

The process of centrifugal formation of the units made of the metals and plastic materials is used in order to manufacture the rotary units of hub type. If one likes to use the antifriction polymeric multi-component compounds, it is necessary to carry out the detailed investigations of compositions polymerization process. In order to determine how the thermodynamic conditions influence on to quality factors, it is necessary to have the special equipment.

Diagnosing turbine engine bearing structures with the aid of FAM-C and FDM-A methods

Diagnosing turbine engine bearing structures with the aid of FAM-C and FDM-A methodsThe diagnostic method FDM-A [2], based on the measurement of the pulsation component frequency modulation, and the FAM-C method, making use of the alternating current frequency, were developed in the Air Force Institute of Technology. The essence of their accuracy consists in "natural" synchronisation of the sampling signal with the angular velocity of the observed kinematic links. These methods make it possible to determine the level of wear of a subsystem and its location during normal operation of the power unit. They provide opportunities for determining numerous parameters of bearings, bearing structures, and the rotor unit. Moreover, the FDM-A method makes it possible to detect resonances in particular elements and their parameters - among others, they provide opportunities for assessing the level of the mechanic quality factor of the examined structure, i.e. the time margin of structure operation until the structure reaches the state of resonance. On the other hand, the FAM-C method provides opportunities for defining numerous parameters of the phenomena connected with the rotor unit. The diagnostic system is connected to an arbitrary point of the electric network (electric junction, for instance) supplied with the direct

Precision sensor assembly for rotating members in a machine tool

A precision sensor assembly for rotating members in a machine tool comprises a rotor unit ( 16 ) rigidly fixed to a rotor portion ( 2 a ) of the machine tool and including a sensor ( 5 ) for detecting vibrations produced by the operation of the machine tool, the sensor ( 5 ) comprising a piezoelectric sensitive element ( 6 ) and members ( 7, 8 ) for mechanical amplification of the vibrations. The members ( 7, 8 ) comprise at least one resonant system composed of an elastic element ( 8 ) and a counter-mass ( 7 ) acting on the piezoelectric sensitive element ( 6 ). The rotor and stator units ( 16, 17 ) comprise inductively coupled transmitting and receiving elements ( 10, 11 ) for transferring the signals from the piezoelectric element ( 6 ) contactless to the stator unit ( 17 ). The stator unit ( 17 ) may include an electric amplifier ( 13 ) for further amplifying the transmitted signals.

Cavitation technology for quality improvement of hydrocarbon fuels

A method is described for altering the physicochemical parameters of petroleum products by inducing a multifactorial effect in a pulsed rotor unit. Experimental data are cited for the pulsed multifactorial energy treatment of atmospheric resids produced by various refineries; these data confirm the effectiveness of the proposed method for improving the quality of hydrocarbon fuels.

Installation of an integrated turbine-generator control system for a pulp mill

A British Columbian pulp mill had experienced the spiral of death many times when the turbine-generator controls were unable to survive the loss of utility tie-line connections. The mill has two high-efficiency rotary turbine-generator units rated 32.2 MVA each and a heat sink capable of generating 47 MW, approximately 87% of the mill power needs, though only 44 MW was being produced. The mill believed that with a load rejection strategy the mill had the potential to continue operation after the loss of a utility tie. In order to ride through the loss of the utility and to fully utilize the process heat sink, the mill needed to replace the 1960s-era turbine-generator control system supplied by the turbine-generator original equipment manufacturer. A triple modular redundant control system for each unit was installed. These systems integrate turbine governor controls and generator excitation control system in a single digital control. The systems are connected in order to jointly coordinate dispatch of real and reactive power demands and achieve load control for the mill. In a staged test, the mill was able to survive the loss of a utility tie-line, and has increased total generation. The new system completely automates the startup, loading, and synchronizing of both generators.

Entropic analysis of adsorption open cycles for air conditioning. Part 1: first and second law analyses

Rotary desiccant units for air-conditioning and ventilation use the principle of adsorption open cycles. In this study, a thermodynamic analysis is first developed that emphasises the open character of the cycle, and especially the consumption of liquid water. Then, the system is ‘closed’ with the help of virtual open systems that exchange mass flows with the cooling unit and only heat fluxes with heat sources. The entropic analysis is developed, first for these virtual systems showing that they are irreversible, second for each component of the unit where heat losses are taken into account. The equations are derived in such a manner that the different irreversibilities can directly be compared. In addition, the concept of entropic mean temperature is introduced and applied to the two virtual systems because it is very helpful for representing the variations of the entropy productions in these systems. In Part 2, these analyses will be applied to experimental data showing that they bring lots of information. Copyright © 2000 John Wiley & Sons, Ltd.

Use of refractory SHS mortar GAMMA-3KhP in rotary furnaces and stationary heating units of nonferrous and ferrous metallurgy

The objective difficulties of the present time have led to substantial changes in the operation of many heating units in nonferrous and ferrous metallurgy, in enterprises producing building materials, in the chemical industry, etc

A new electrohydraulic energy converter for a left ventricular assist device.

An energy converting system that can function for years without maintenance is required for the drive of a left ventricular assist device (LVAD). To meet the requirements of safety, the energy converter should have a simple design with few moving elements. The design applied herein has only one moving part and thus has greater inherent safety than competing systems. The only moving part is the rotor unit, comprised of the impeller of a centrifugal pump, the rotor of an electric motor, and the rotor of an electric axial actuator. A reversal of flow of the transmitter fluid can be achieved with an axial shift of this rotor unit. This fluid acts on the outer surface of a blood chamber and enables it to draw in blood and to expel it. Valves direct the flow of blood. The energy converter performs a flow of 12 L/min at a motor speed of 6,000 rpm against a pressure head of 115 mm Hg according to an output of the pulsatile blood pump of 5 L/min.

Limits on modification of epitrochoid used in rotary piston machines and the effects of modification on geometric volume displacement and ripple

Modified epitrochoids and their associate envelopes are already established as rotor-stator elements of form-closed rotary piston hydrostatic units. Published works are inadequate to explain various features of such machines. In the present work a generalized method has been developed to find out and analyse flow rate, ripple, speed variation, etc. in different (kinematic) models. The effect of the variation in geometric parameters and the practical limits on modifications are also studied. Sample results which help in the preliminary selection of parameters to design such machines for a desired output with optimum performance are also presented.

Multistage centrifugal extractors

With centrifugal extractors recently gaining importance in the extraction technology of nuclear-power materials, the authors have designed the ETs models of multistage centrifugal extractors featuring liquid mixing under gravity and free-flow phase discharge. The specifications are given and the models are shown. The extractors can be used in both fast and slow mass-transfer processes. The mechanical reliability of the centrifugal extractors depends to a large extent on the reliability of the bracket bearing and of the rotor unit and drive as a whole.

Heat conduction in a plane wall subject to periodic temperature changes

Analytical solutions for the heat conduction in a plane wall with periodic temperature variations at the wall surface are presented. Series and asymptotic developments of these solutions are deduced. The results are important for the calculation of the heat transfer in rotary kilns or other rotaring units.

Thermosyphons as heat transfer elements in large air pre-heaters—The testing of a 16 m 20 kW thermosyphon

Preliminary work suggested that static recuperative heat exchangers using thermosyphons could be cost effective in the replacement of the rotary regenerative units used as air pre-heaters for large, 660 MWe, power station boilers. A study indicated that the thermosyphons in such a heat exchanger would be approx. 16 m long and must be capable of transferring 20k W each. A copper/water thermosyphon test rig 16 m long was built to investigate the performance of long thermosyphons. Some test results obtained with this rig are reported here.

Quasi-linear rheological behaviour of polymer melts: Comparison between mechanical and improved flow birefringence measurements

The latest improvement of the rotor unit (cone- and plate-type) for the measurement of the flow-birefringence of polymer melts is described. As a consequence of this improvement, the influence of parasitic birefringences, as produced in the corners near the windows, is minimized. It is shown that the limitation of the range of available rates of shear, as experienced with previous versions of the apparatus, was due to those parasitic birefringences which predominated at rates of shear where the main birefringence caused an optical path difference of one, two or more whole wavelengths (fringes) and was, as a consequence, virtually zero. This explains why great troubles were experienced in particular with polymers possessing a high back-bone anisotropy. The validity of the linear stress-optical rule up to shear rates, where melt fracture occurs in capillary flow, is well understood in terms of the “wriggling motion” of chain molecules. Comparison with direct mechanical measurements was very satisfactory.

Analysis of zones in the deep concentration of solutions in a horizontal rotor unit

Analysis of zones in the deep concentration of solutions in a horizontal rotor unit

Heat and Momentum Transfers: Multiple-Disc Rotor Units

An investigation has been carried out to determine the performance characteristics of a multiple-disc rotor device used as a combined fan/heat exchanger. The advantages of such a system, when applied for example to an air-conditioning system, stem primarily from the simplicity of design and compact nature of the equipment. The assessment of the particular test unit as a fan was done under normal atmospheric conditions using air as the working fluid. A speed range from 550 to 1290 rpm was used in these tests. The maximum efficiency of the momentum transfer from the rotor to the fluid was about 14 percent. The unit capability as a heat exchanger using air flow under normal atmospheric conditions may be judged by the maximum heat transfer effectiveness of about 40 percent. Rotor speeds were varied in the range 700 to 1600 rpm, and at each rotational speed the ratio of the mass flow in the cool stream to that in the hot stream was varied from 0.48 to 1.30. Two different techniques were used in an endeavor to predict the performance of the experimental unit. Of these, the more successful was that based on the assumption that a turbulent boundary layer covered the rotating disc. However, the simpler approach, using calculated friction factors, may well prove acceptable for some engineering applications. The results from each of the prediction techniques are given for comparison with the test results.