l. huang

In pursuit of enhanced accuracy in the performance prediction and optimization of high-load compressors, this study emphasizes the significance of empirically measured clearance values associated with variable guide vanes and stators in engineering applications. Utilizing these empirical data, we conduct a refined modeling approach for the variable guide vanes and stators. A comprehensive three-dimensional numerical simulation methodology is employed to examine the impact and underlying flow mechanisms of the adjustable blades with clearances in a nine-stage compressor, concurrently optimizing the positional parameters of the clearances to augment the aerodynamic performance of the compressor. The findings of this investigation reveal that the omission of clearances and platform geometry of adjustable blades in numerical simulations can lead to an overestimation of both maximum flow rates and the overall stability margins. Driven by the pressure differential between the suction and pressure sides, clearance leakage flow is generated at the leading edge of the end wall of adjustable blades, exacerbating flow separation in the end wall corner region and potentially resulting in corner stall phenomena. By adjusting the platform of the adjustable stators, which experience corner stall predominantly, the leading edge separation resulting from the interaction of the flow near the end wall and the leakage flow from the leading edge clearance is mitigated. Consequently, the maximum flow rate of the compressor is increased by approximately 0.48 kg/s, the overall stability margin is enhanced by approximately 7.52%, and the peak efficiency experiences an improvement of about 0.4%.

To investigate the impact of perioperative rapid rehabilitation nursing on pelvic floor function of patients during transvaginal natural cavity endoscopic hysterectomy using perineal Four-dimensional (4D) ultrasound imaging technique. A total of 60 patients undergoing natural cavity endoscopic hysterectomy were evenly divided into control group (CG) and observation group (OG). The CG adopted perioperative nursing mode, and the OG adopted rapid rehabilitation nursing on the basis of the CG. The perineal 4D ultrasound imaging technology was used to evaluate the postoperative pelvic floor function parameters and the incidence of pelvic floor function abnormalities in the two groups. During anal retraction, the OG exhibited a substantially higher urethral rotation angle and bladder neck mobility compared to the CG (P < 0.05). Under resting conditions, the ultrasonic parameters of the two groups did not differ significantly (P > 0.05). The OG's ultrasonography parameters were substantially lower than the CG's under the highest Valsalva condition (P < 0.05). The incidence of internal urethral orifice infundification did not differ between the two groups (P > 0.05). Compared to the OG, the CG had a considerably higher incidence of cystocele (P < 0.05). There was a clear difference in pelvic prolapse distance between the two groups (P < 0.05). 4D ultrasound is conducive to accurately identifying the morphological structure and function of the pelvic floor in patients with hysterectomy, and provides guidance for the formulation of the rehabilitation treatment plan for the pelvic floor muscle of the patients.

This paper studies the evolution and fluid distribution characteristics of a high-speed projectile’s cavity in the water based on joint research, a method involving experiment and numerical simulation. Specifically, we develop an experimental platform and a numerical calculation model for a high-speed projectile to observe its initial cavity evolution characteristics in the water at different velocities and close ranges. Additionally, this work investigates the evolution mechanism of the cavitation process and its fluid distribution law inside the cavity and studies the evolution characteristics of the cavitation stage under different velocities. The results reveal that after the projectile enters the water, the cavity is gourd-shaped and symmetrical, with a necking phenomenon at the tail and the cavity falling off. The cavitation process can be divided into the surface closure, saturation, deep closure, and collapse stages according to the fluid distribution changes in the cavity. Suppose the projectile has a certain speed with the water, its velocity increases. In that case, the cavity generation rate decreases, the growth rate of the water vapor volume in the cavity decreases, the peak water vapor volume content reduces, and the volume of air in the saturation phase of the cavity becomes increases having a range of 6% to 9%. Additionally, the cavity surface closure dimensionless time grows logarithmically as the velocity changes from 0 m/s to 500 m/s, the cavity saturation dimensionless time decreases approximately linearly, and the cavity depth closure dimensionless time is unaffected by velocity changes.

Low-frequency buffeting is a common problem in automobile wind tunnels, it induces pulsations of pressure and velocity in the test section. A 1:15 3/4 open-jet return-type scaled wind tunnel was used for this research, and numerical simulations and tests were implemented to study the flow characteristics of the jet shear layer in a model wind tunnel. The results show that guide devices on the inner wall of the nozzle can effectively reduce the low-frequency buffeting, but the presence of the devices deteriorated the axial static pressure gradient of the flow in the test section. The shape of the guide devices was optimized through the Explorative Gradient Method, and numerical simulations were carried out. An optimal shape can effectively reduce the low-frequency buffeting and ensure flow field uniformity in the test section. Finally, the reliability of the numerical simulation and the practicability of the optimal case were verified through a hot wire test and a microphone test.