Rotational speed

About: Rotational speed is a research topic. Over the lifetime, 23327 publications have been published within this topic receiving 151696 citations. The topic is also known as: speed of revolution & revolution rate.

Low-temperature refrigeration air conditioner and wind speed control method thereof

Abstract: The invention discloses a low-temperature refrigeration air conditioner and a wind speed control method thereof. The low-temperature refrigeration air conditioner comprises a wind speed control deviceof an outdoor unit fan. The wind speed fan control device comprises a temperature detection unit, a fan control unit and the outdoor unit fan, wherein the temperature detection unit detects the temperature of a condenser of the air conditioner so as to obtain a simulated condensation temperature; the fan control unit generates control signals of the rotation speed change and on-off of the fan according to the simulated condensation temperature; and the outdoor unit fan responds to the control signals of the fan control unit and generates corresponding outdoor unit wind speed. The method for controlling the wind speed of the low-temperature refrigeration air conditioner controls the rotation speed change and on-off of the fan by simulating the condensation temperature of the condenser so as to provide different wind speeds for an outdoor unit. Because of simulating a pressure signal by detecting a temperature signal, the air conditioner and the method avoid direct contact between a wind speed control system and a refrigerant system so as to avoid leakage.

Analysis of the impact of impeller geometry on the turbulent statistics inside a fan-stirred, cylindrical flame speed vessel using PIV

Abstract: Turbulence statistics of three impellers with different geometric features were measured using particle image velocimetry inside a Plexiglas model (~1:1 scale) of a cylindrical flame speed vessel (30.5 cm ID × 35.6 cm L). With four impellers arranged in a central-symmetric configuration, turbulence intensities between 1.2 and 1.7 m/s with negligible mean flow (0.1u′) were attained at the lowest fan speeds. Acceptable ranges for homogeneity and isotropy ratios of the velocity fields were set within a narrow bandwidth near unity (0.9–1.1). Homogeneity ratios were unaffected by changes to the impeller geometry, and the prototype with the higher number of blades caused the flow to become anisotropic. The integral length scale of the flow fields varied between 27 and 20 mm, which correlates well with those typically observed inside a gas turbine combustor. The mechanism to independently vary the intensity level and the integral length scale was established, where turbulence intensity level was dependent on the rotational speed of the fan, and the integral length scale decreased with increasing blade pitch angle.

Apparatus for detecting rotational speed

Abstract: An apparatus for a rotational speed detecting includes a rotating disc having plural slits in a circumferential direction. A radiant element radiates light rays through the slits. A photodetector receives the rays radiated by the radiant element. Peak detectors detects peak points of the detected signal and a calculator calculates a rotational speed. The photodetector include two photodetectors separated by a distance ΔL.

Rotating electrical machine control system and vehicle drive system

Abstract: A rotating electrical machine control system includes a rotating electrical machine, a frequency conversion portion, a voltage conversion portion, a torque limitation portion, and an abnormality detection portion. The torque limitation portion limits generation of a positive torque in a region of less than a rotational speed lower limit threshold value where a rotational speed of the rotating electrical machine is less than zero, and sets a region in which the positive torque is generated to a region of the rotational speed lower limit threshold value or greater, and the torque limitation portion limits generation of a negative torque in a region of greater than a rotational speed upper limit threshold value where the rotational speed of the rotating electrical machine is greater than zero, and sets a region in which the negative torque is generated to a region of the rotational speed upper limit threshold value or less.

Method and device for suppressing chattering of work machine

Abstract: Disclosed is a method for suppressing chattering of a work machine comprising a step (S1) of detecting vibration occurring when the rotation of a bit or a work (W) is started, a step (S3) of determining whether or not the vibration detected after the time when the rotation is started exceeds a threshold, a step (S4) of analyzing the vibration by Fourier series expansion when the vibration is determined to have exceeded the threshold, and a step (S21) of adjusting the rotational speed of the spindle.