Showing papers on "Critical speed published in 1979"
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28 Feb 1979
TL;DR: In this article, a flywheel set for accumulating energy with elastically supported bearings, resulting in a low critical speed, lying at all times under the operational flywheelspeed.
Abstract: Flywheel set for accumulating energy with elastically supported bearings, resulting in a low critical speed, lying at all times under the operational flywheelspeed. The axial thrust taking bearings, or one bearing, may be operating with magnetic forces. Spherical pivot bearings may be fitted both at the bottom and at the top of the rotor.
30 citations
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TL;DR: In this paper, the authors developed an algorithm to analyze the dynamic response of a continuous guideway resting on equally spaced supports being traversed by a moving vehicle and determined a critical speed, one at which the amplitude of the guideway displacement becomes large.
13 citations
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17 May 1979
TL;DR: In this paper, a rotor assembly for a gas turbine engine having a critical speed characteristic well above the operating speed is described, and various construction details which enhance axial stiffness of the rotor assembly and which shield a portion of the disk from working medium gases are developed.
Abstract: A lightweight, rotor assembly for a gas turbine engine having a critical speed characteristic well above the operating speed is disclosed. Various construction details which enhance the axial stiffness of the rotor assembly and which shield a portion of the disk from working medium gases are developed. The rotor assembly employs a frustoconical member to connect a shaft to the disk.
9 citations
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TL;DR: In this article, an analytical expression for the low speed transfer function of a railway vehicle is derived, from which conclusions can be drawn regarding the effect of the elastic connections between wheelsets on dynamic behaviour.
Abstract: SUMMARY An important function of a bogie of a railway vehicle (or of the running gear of guided vehicles in general) is to guide or steer the vehicle along the course of the track while isolating the vehicle and its payload as well as possible from unintended but inevitable imperfections in the position of the track. Against this background, an analytical expression is derived for the low speed transfer function of a bogie, from which conclusions can be drawn regarding the effect of the elastic connections between wheelsets on dynamic behaviour. At higher speeds inertia effects of the unsprung masses have a negative effect on dynamic behaviour, the magnitude of this effect being different for different types of elastic connections. This is also reflected in the critical speed and the interaction between body and bogie. With respect to the wear of wheels and rails on curved track, the range of radii of curves which can be traversed without flange contact and, for smaller radii, the rate of increase of flan...
5 citations
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17 May 1979
TL;DR: In this article, a locking device, preferably actuated automatically by a speed sensor, consolidates the shaft with the tube until the system surpasses the critical speed of the tool shaft.
Abstract: A mounting for a shaft of a tool rotating at high speed comprises a rotatably journaled tube with an axial bore of a diameter exceeding that of the tool shaft. The latter is held in that bore by resilient inserts, such as soft springs or O-rings, whose elasticity coefficient is so chosen that the shaft has a critical speed well below the operating speed of the tool. A locking device, preferably actuated automatically by a speed sensor, consolidates the shaft with the tube until the system surpasses the critical speed.
4 citations
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01 Apr 1979
TL;DR: In this paper, the unbalance response characteristics of the vertical pumps for the Clinch River Breeder Reactor Plant are investigated, and several design options are explored for raising shaft critical speed beyond 125% of maximum operating speed.
Abstract: The unbalance response characteristics of the vertical pumps for the Clinch River Breeder Reactor Plant are investigated. Finite-element shell and beam models representative of the pump-motor structure including the rotating assembly are developed to assess structural stiffnesses of dominant joints as well as the foundation support stiffness so as to exclude the danger of resonant excitation during normal operation. Less than four mils peak-to-peak vibration amplitude at the pump tank discharge nozzle results from just 10% frequency separation between the first rocking mode and the maximum operating speed of 1116 RPM, based on 0.5% modal damping ratio and balance quality grade of ISO/ANSI G2.5 for the rotating components: motor rotor, pump shaft, Bendix diaphragm-type flexible coupling, and centrigual double-suction impeller. Several design options are explored for raising shaft critical speed beyond 125% of maximum operating speed.
3 citations
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12 Mar 1979TL;DR: In this paper, a flexible rotor system used for two-plane laser balancing and an experimental demonstration of the laser material removal method for balancing is described, where a test rotor was modified to accept balancing corrections using a laser metal removal method while the rotor was at operating speed.
Abstract: This paper describes a flexible rotor system used for two-plane laser balancing and an experimental demonstration of the laser material removal method for balancing. A laboratory test rotor was modified to accept balancing corrections using a laser metal removal method while the rotor is at operating speed. The laser setup hardware required to balance the rotor using two correction planes is described. The test rig optical configuration and a neodymium glass laser were assembled and calibrated for material removal rates. Rotor amplitudes before and after balancing, trial and correction weights, rotor speed during operation of laser, and balancing time were documented. The rotor was balanced through the first bending critical speed using the laser material removal procedure to apply trial weights and correction weights without stopping the rotor.
2 citations
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TL;DR: In this article, a two-support model of the propeller and tailshaft was used to estimate the critical speed of a vessel shafting system, which is suitable for manual calculation or use with a small, desk-top calculator.
Abstract: This paper presents a calculation method, suitable for manual calculation or use with a small, desk-top calculator, for estimating the propeller-excited whirling critical speed of a shafting system The method is especially adaptable to use with a small programmable calculator Based on a two-support model of the propeller and tailshaft similar to that used in earlier whirling calculations, this method "brackets" the natural frequency by first assuming the forward end of the tailshaft to be simply supported, then repeating the calculation, assuming the forward end to be fixed This gives an upper and lower limit on the natural frequency The actual natural frequency is estimated by interpolation between these two values The proposed calculation method includes propeller gyroscopic and inertia effects, as well as shaft mass effects Entrained water may also be taken into account Comparisons between the results of the proposed hand calculation and the results of other well-known methods of whirling analysis are presented for a typical vessel shafting system Extensions of the proposed calculation to include the effects of the line shafting and the sterntube bearing stiffness are also presented
2 citations
01 Jan 1979
TL;DR: In this paper, a high speed free car-body truck running on an aligned track under optimal geometric conditions is shown. But the maximum running speed will be lower than the critical speed inherent to the system which is determined by the first eigenvalue of the matrix for which the real part is small and positive.
Abstract: Matrix (A) shows the dynamic behavior of a high speed free truck running on an aligned track under optimal geometric conditions. The maximum running speed will be lower than the critical speed inherent to the system which is determined by the first eigenvalue of the matrix for which the real part is small and positive. The increase of this critical speed has been observed by an increase of the connection stiffness between car-body and truck. In fact, the car-body truck connection includes more than the classical connection. It includes hydraulic damping devices whose force-displacement diagram is similar to that of a friction damping device. After considering the elastic deformation of the connecting system ensured by the damping devices between truck and car-body, and the connecting springs between truck and car-body mounted is parallel, we observe a drawback torque relative to the truck. This characteristic can be compared to an hysteresis cycle.
1 citations
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25 May 1979
TL;DR: In this paper, a rotational frequency control of a water supply pump and an actuating turbine is discussed. But the authors do not specify a specific operating frequency for the water supply operation.
Abstract: PURPOSE:To enable such a rotational frequency control of a water supply pump and a water supply pump actuating turbine which have each a critical speed below the range of working speed that if the steam conditions are lowered below a predetermined level the water supply pump and the actuating turbine therefore are not at all caused to run at a speed within the critical speed range. CONSTITUTION:After initiation of starting of a turbine, a deflection signal between a rotational frequency preset signal from an automatic starter 8 and an actual rotational frequency signal from an electromagnetic pick-up 4 is applied by way of an amplifier 9 to a lower value selection circuit 10 whereat the signal from the amplifier 9 is selected to effect an appropriate running of the turbine 2. Then, if the turbine 2 gets to a rotational frequency at which it can start its water supply operation, a signal from another amplifier 13 which is connected to a water supply controller 11 is selected at the selection circuit 10 to effect an appropriate running of the turbine 2. Thus constituted controller is additionally provided with a rotational frequency holding circuit 20 adapted to output a deflection signal between the actual rotational frequency signal and a holding rotational frequency preset signal, a higher value selection circuit 22, and so on.