Influences of eccentricity ratio on the internal flow and cavitation characteristics of progressing cavity pump

A Progressing Cavity Pump (PCP) works by forming a progressive seal cavity through the eccentric rotation of rotor. PCP parameters, such as eccentricity ratio [Formula: see text], can influence its performance and cavitation characteristics. The internal correlation among clearance fluid, cavitation characteristics, and pump performance should be explored to reveal the variation laws of internal flow and cavitation characteristics in PCP under different [Formula: see text]. In this study, a contrast analysis on external characteristics (e.g. volume efficiency) of pump with different eccentricity ratios was carried out by combining an RNG [Formula: see text] turbulence model based on Singhal full-cavitation model and the model pump test method. Moreover, gas volume distribution of PCP was analyzed and the optimal value range of eccentricity ratio was proposed. Results demonstrate that the axial force and axial power of PCP basically remain the same, volume efficiency increases, and cavitation performance decreases with the increase of [Formula: see text], and the optimal value for [Formula: see text] ranges from 0.17 to 0.24. In addition, a revised NPSHQ is proposed to quantify the cavitation characteristics of PCP.

Ideal Oscillation of a Hydrogenated Deformable Rotor in a Gigahertz Rotation–Translation Nanoconverter at Low Temperatures

It was discovered that large-amplitude axial oscillation can occur on a rotor with an internally hydrogenated deformable part (HDP) in a rotation–translation nanoconverter. The dynamic outputs of the system were investigated using molecular dynamics simulations. When an input rotational frequency (100 GHz > ω > 20 GHz) was applied at one end of the rotor, the HDP deformed under the centrifugal and van der Waals forces, which simultaneously led to the axial translation of the other end of the rotor. Except at too high an input rotational frequency (e.g., >100 GHz), which led to eccentric rotation and even collapse of the system, the present system could generate a periodic axial oscillation with an amplitude above 0.5 nm at a temperature below 50 K. In other ranges of temperature and amplitude, the oscillation dampened quickly due to the drastic thermal vibrations of the atoms. Furthermore, the effects of the hydrogenation scheme and the length of HDP on the equilibrium position, amplitude, and frequency of oscillation were investigated. The conclusions can be applied to the design of an ideal nano-oscillator based on the present rotation–translation converter model.

Right Upper Lobe Torsion after Right Lower Lobectomy: A Rare and Potentially Life-Threatening Complication

An 84-year-old woman was referred to our institution with suspected right lung cancer. Subsequently, she underwent thoracoscopic right lower lobectomy without mediastinal lymph node dissection. Postoperatively, she complained of dyspnea and developed arterial oxygen desaturation after 12 h and acute respiratory failure (ARF). An emergency chest computed tomography revealed the right upper bronchial stenosis with hilar peribronchovascular soft tissue edema because the middle lung lobe had been pushed upward and forward and the right upper lung lobe had twisted dorsally. Emergency bronchoscopy revealed severe right upper bronchial stenosis with an eccentric rotation and severe edema. The bronchia stenosis was successfully treated with glucocorticoids and noninvasive positive pressure ventilation for ARF.

Analysis of operating noise characteristics and contribution for automotive seat backrest adjuster

Background/Objectives: This study involved basic research on operating noise in an automotive seat backrest adjuster through analysis of noise sources, noise source contributions, and seat pad noise reduction effects.Methods/Statistical analysis: The test product was a driver seat of 3300cc commercial sedan. First, basic data is obtained through analysis of driving mechanism of seat backrest adjuster. Based on this, vibration and noise characteristics were analyzed by operating test of backrest adjuster, and contribution analysis to noise sources was performed. Finally, by analyzing the effect of noise reduction on the seat pad, the effect of each noise source on the backrest operating noise was determined.Findings: First, it was confirmed that the low frequency fluctuation caused by the total noise is dependent on change in the load generated by eccentric rotation of the recliner gear. Therefore, it was found that the design of the recliner gear teeth was a decisive factor in controlling the motor load. Second, the 20th order (1,320Hz) of the DC geared motor was the main cause of operating noise, which was derived from friction noise of brush-commutator and torque ripple noise. This noise accounted for more than 55% of total operating noise. In addition, the 30th order amounted to approximately 18%. In other words, the harmonic components of the DC geared motor created most of the noise, and changing the brush material and reducing torque ripple is expected to significantly improve the overall operating noise. Lastly, as a result of the seat pad noise reduction effect, total power decreased by more than 11dB (A). In addition, it was confirmed that the 20th order cause of the main noise was reduced by about 45%p.Improvements/Applications: The noise contribution of the seat recliner adjuster derived from this study can be used as a basic data for noise reduction.

Vibration analysis of a thin eccentric rotating circular cylindrical shell

In this study, the vibration characteristics of a thin eccentric rotating circular cylindrical shell with simply supported boundary conditions are studied. Energy formulations based on Flügge’s thin shell theory, Hamilton’s principle, and the method of linear approximation are applied to derive the governing equations of motion. In addition to the effects of centrifugal and Coriolis forces, the effect of nonuniform initial stresses resulting from eccentric rotation are taken into account. The natural frequencies of the shell with respect to rotating speed and eccentricity are obtained using Galerkin’s method. To validate the present analysis, comparisons are carried out with the results in published literatures and finite element analysis, and good agreements are obtained. The effect of the eccentricity on the natural frequency of the eccentric rotating cylindrical shell is investigated. Some further numerical results are given to illustrate the irregular frequency mutation behaviors resulting from the eccentricity. The effects of the eccentricity on the critical speed and flutter speed of the eccentric rotating circular cylindrical shell are also investigated.