bluuebunny/crossref_metadata_2025 huggingface dataset:
ROLE OF CERVICOMASTOID AND RETROAURICULAR TUBE PEDICLES IN PINNA RECONSTRUCTION
Authors: TAKKAR K. L. , SRIVASTAVA J. L.
Published: March 2024

The role of cervicomastoid and retroauricular ll1bepedicles in the reconstruction of pinna—either congenitally deformed or traumatically severed is presented. The disadvantages of the conventional procedure of burying carved costal cartilages under the retroauricular skin and producing a pinna from it at a future date have been brought out. The advantages of the two flaps used by us on ten patients have been enumerated. The pinna thus formed was found to be nearer to normal shape and texture and yet the described procedure was found not to be unduly time consuming or risky.
USE OF PENILE IMPLANT
Authors: TEWARI J. N. , SANDHIR R. K.
Published: March 2024

This paper is based an a study of 4 cases of impotence in which flexi-rod penile implant was used successfully. It is felt that semi-rigid hinged penile implant should be used in such cases.
BILATERAL GIANT BREASTS IN AN ADOLESCENT FEMALE
Authors: DAVE B. P.
Published: March 2024

Giant fibro-adenoma (Cystosarcoma phylloides) in a girl of 13 years of age is being presented because of its extreme rarity. It is highly probable that the rapid growth of these tummours in the pubertal phase of adolescent females is due to either excessive oestragen stimulation or lack of its antagonists. The present case has been followed-up for two years and there has been no recurrence or any problem after surgery.
DISTALLY BASED SUPERFICIAL SURAL ARTERY FLAP
Authors: Gupta Ashish , Prakash P J , Thomas Binu P , Dhanraj Prema
Published: March 2024

We describe our experience with the use of distally based superficial sural artery flap for coverage of defects in lower third of leg and foot in 12 patients. In 9 patients the flap was successfully transferred and in 3 cases marginal necrosis of flap occurred. This flap has a constant and reliable blood supply and does not sacrifice a major artery. Other advantages of this flap are easy dissection and is a one stage procedure. In most patients the skin graft site is cosmetically unacceptable.
Correction of Constricted Ear : A Simple Technique
Authors: Kumar P , Thomas P C , Bhaskara K G
Published: March 2024

A simple technique of correction of constricted ear utilizing standard basic principles of plastic surgery is described. Lengthening of the helical lim was achieved byv-y plasty, reconstruction of antihelical fold by Converse-Mustarde procedure and correction of drooping of the upper part of ear by excision of planned amount of skin from superior part of post auricular sulcus.
Alternative Tests in Demonstrating the Presence of Palmaris Longus
Authors: Mishra S
Published: March 2024

The presence of Palmaris longlls is classically demonstrated by a combination afforced opposition of the thumb and mild flexion of the wrist. Two new tests have been described. These are alternative to the classical test and also offer some advantages over it in certain situations.
Dorso-palmar triangular finger flap-A new advancement flap for cover of finger amputations-A preliminary report
Authors: Mishra S
Published: March 2024

A triangular V-Y type advancement flap on the finger has been designed, which advances skin from over the whole circumference of the finger, which includes both palmar and dorsal skin. The flap is sensate too. It is indicated for finger and thumb amputations proximal to the body oethe nail. Six were raised with five successes and one partial necrosis. This is a preliminary report on a new nap.
Partial Excision of Giant Plexiform Neurofibromatosis
Authors: Kumar P , Anand N , Bhaskara K G , Raja A , Ganesh K
Published: March 2024

Seven cases of plexiform neurofibromatosis, which underwent single or multiple partial excisions from 1996-2000 were reviewed for quality of scar, aesthetic results and any other complication. Early results were satisfactory. Follow up period was inadequate to comment on the malignant degeneration at the surgery site.
The constricted ear deformity-A case report
Authors: Ghildiyal Harish C. , Misra Tatsat
Published: March 2024

A case report of constricted ear deformity and its correction with Musgrave's technique is presented.
An improved design for virtual synchronous generator control loop based on synergy theory
Authors: Wang Fangfang , Zeng Yun , Qian Jing , Guo Zhicheng
Published: March 2024

Virtual synchronous generator (VSG) technology has achieved some results in distributed generation networks and enhanced system stability. For problems that may occur in the system due to ignoring parameter linkages, this paper designs a synergistic controller that establishes the connection between the active frequency and the reactive voltage control loop based on synergy theory. As the output of the synergetic controller, the derived control law u is added to the power frequency control in the form of negative feedback. Two disturbance forms, a step disturbance, and a three-phase short-circuit fault, are set up. The conventional droop control and synergetic droop control results are compared using a MATLAB simulation system. Then, the system parameter variations were studied and analyzed, and the sensitivity of the control system with different values of parameters K1, K2, and K3 in the case of a three-phase short circuit was analyzed, which provides a reference guide for selecting parameters in later control optimization. Finally, the control effectiveness of a multi-machine VSG system was tested. The simulation results show that the proposed method has a pronounced effect on making the system stabilize quickly, which illustrates the effectiveness of this technique.
Acoustic meta-stethoscope for cardiac auscultation
Authors: Dai Ruoxue , Chen Zhengji , Liu Jingjing , Yang Jing , Liang Bin , Cheng Jian-Chun
Published: March 2024

Straight cylindrical stethoscopes serve as an important alternative to conventional stethoscopes, whose application in the treatment of infectious diseases might be limited by the use of protective clothing. Yet their miniaturization is challenging due to the long wavelength of low-frequency cardiac sounds. Here, we present and experimentally demonstrate an acoustic meta-stethoscope with subwavelength size, simple fabrication, and easy assembly for high-sensitivity cardiac auscultation, which simply comprises multilayered perforated round plate units and a cylindrical shell. We elucidate our proposed mechanism by analytically deducing the frequency response equation and the effective material properties of the meta-stethoscope, which proves that the equivalent acoustic propagation path is substantially increased by the metamaterial with a high refractive index, enabling downscaling the device to a subwavelength footprint. The auscultation performance of the meta-stethoscope is experimentally characterized by detecting the cardiac sound signal from the human heart through different clothing, showing an expected sensitivity enhancement exceeding 10 dB within the predicted working frequency regardless of the type of clothing. Our portable, detachable, yet effective meta-stethoscope opens a route to the metamaterial-based stethoscope research paradigm, with potential applications in diverse scenarios such as medical diagnosis and acoustic sensing.
An opportunity to transform Australia’s neo-colonial health system
Authors: Veasey Alicia E.
Published: March 2024

The ‘modern’ value-based healthcare (VBHC) movement provides an opportunity to not only reform health care towards a more equitable, community-centred system, but to also acknowledge, honour and learn from global Indigenous knowledge, systems, and ways of valuing knowing, being and doing. For Australia as a settler-colonial state, efforts to implement VBHC here are doomed to fail until the continued legacy of settler-colonial violence and systemic racism pervading Australia’s healthcare system is acknowledged, addressed and ameliorated.
Root photosynthesis prevents hypoxia in the epiphytic orchid Phalaenopsis
Authors: Brunello Luca , Polverini Ester , Lauria Giulia , Landi Marco , Guidi Lucia , Loreti Elena , Perata Pierdomenico
Published: March 2024

Orchids (Phalaenopsis spp.) growing in tropical and subtropical regions are epiphytes. As such, they grow on trees with the root system utilised to anchor themselves to tree branches. These roots are highly specialised, display a large diameter and are often green, suggesting the ability to carry out photosynthesis. However, the role of photosynthesis in orchid roots is controversial. Orchids that are leafless can photosynthesise in their roots, thus indicating that some orchid roots carry out photosynthesis in a similar manner to leaves. However, the primary site of photosynthesis in orchids are in their leaves, and the roots of epiphytic orchids may mostly conduct internal refixation of respiratory CO2. Besides contributing to the overall carbon metabolism of orchid plants, oxygen produced through root photosynthesis may also be important by alleviating potential root hypoxia. The bulky tissue of most epiphytic orchid roots suggests that oxygen diffusion in these roots can be limited. Here, we demonstrate that the bulky roots of a widely commercially cultivated orchid belonging to the genus Phalaenopsis are hypoxic in the dark. These roots are photosynthetically active and produce oxygen when exposed to light, thus mitigating root hypoxia.
Insights into hippocampal perfusion using high-resolution, multi-modal 7T MRI
Authors: Haast Roy A. M. , Kashyap Sriranga , Ivanov Dimo , Yousif Mohamed D. , DeKraker Jordan , Poser Benedikt A. , Khan Ali R.
Published: March 2024

We present a comprehensive study on the non-invasive measurement of hippocampal perfusion. Using high-resolution 7 tesla arterial spin labeling (ASL) data, we generated robust perfusion maps and observed significant variations in perfusion among hippocampal subfields, with CA1 exhibiting the lowest perfusion levels. Notably, these perfusion differences were robust and already detectable with 50 perfusion-weighted images per subject, acquired in 5 min. To understand the underlying factors, we examined the influence of image quality metrics, various tissue microstructure and morphometric properties, macrovasculature, and cytoarchitecture. We observed higher perfusion in regions located closer to arteries, demonstrating the influence of vascular proximity on hippocampal perfusion. Moreover, ex vivo cytoarchitectonic features based on neuronal density differences appeared to correlate stronger with hippocampal perfusion than morphometric measures like gray matter thickness. These findings emphasize the interplay between microvasculature, macrovasculature, and metabolic demand in shaping hippocampal perfusion. Our study expands the current understanding of hippocampal physiology and its relevance to neurological disorders. By providing in vivo evidence of perfusion differences between hippocampal subfields, our findings have implications for diagnosis and potential therapeutic interventions. In conclusion, our study provides a valuable resource for extensively characterizing hippocampal perfusion.
How persistent infection overcomes peripheral tolerance mechanisms to cause T cell–mediated autoimmune disease
Authors: Yin Rose , Melton Samuel , Huseby Eric S. , Kardar Mehran , Chakraborty Arup K.
Published: March 2024

T cells help orchestrate immune responses to pathogens, and their aberrant regulation can trigger autoimmunity. Recent studies highlight that a threshold number of T cells (a quorum) must be activated in a tissue to mount a functional immune response. These collective effects allow the T cell repertoire to respond to pathogens while suppressing autoimmunity due to circulating autoreactive T cells. Our computational studies show that increasing numbers of pathogenic peptides targeted by T cells during persistent or severe viral infections increase the probability of activating T cells that are weakly reactive to self-antigens (molecular mimicry). These T cells are easily re-activated by the self-antigens and contribute to exceeding the quorum threshold required to mount autoimmune responses. Rare peptides that activate many T cells are sampled more readily during severe/persistent infections than in acute infections, which amplifies these effects. Experiments in mice to test predictions from these mechanistic insights are suggested.
Quafu-RL: The cloud quantum computers based quantum reinforcement learning
Authors: Jin 靳 Yu-Xin 羽欣 , Xu 许 Hong-Ze 宏泽 , Wang 王 Zheng-An 正安 , Zhuang 庄 Wei-Feng 伟峰 , Huang 黄 Kai-Xuan 凯旋 , Shi 时 Yun-Hao 运豪 , Ma 马 Wei-Guo 卫国 , Li 李 Tian-Ming 天铭 , Chen 陈 Chi-Tong 驰通 , Xu 许 Kai 凯 , Feng 冯 Yu-Long 玉龙 , Liu 刘 Pei 培 , Chen 陈 Mo 墨 , Li 李 Shang-Shu 尚书 , Yang 杨 Zhi-Peng 智鹏 , Qian 钱 Chen 辰 , Ma 马 Yun-Heng 运恒 , Xiao 肖 Xiao 骁 , Qian 钱 Peng 鹏 , Gu 顾 Yanwu 炎武 , Chai 柴 Xu-Dan 绪丹 , Pu 普 Ya-Nan 亚南 , Zhang 张 Yi-Peng 翼鹏 , Wei 魏 Shi-Jie 世杰 , Zeng 曾 Jin-Feng 进峰 , Li 李 Hang 行 , Long 龙 Gui-Lu 桂鲁 , Jin 金 Yirong 贻荣 , Yu 于 Haifeng 海峰 , Fan 范 Heng 桁 , Liu 刘 Dong E. 东 , Hu 胡 Meng-Jun 孟军
Published: March 2024

With the rapid advancement of quantum computing, hybrid quantum–classical machine learning has shown numerous potential applications at the current stage, with expectations of being achievable in the noisy intermediate-scale quantum (NISQ) era. Quantum reinforcement learning, as an indispensable study, has recently demonstrated its ability to solve standard benchmark environments with formally provable theoretical advantages over classical counterparts. However, despite the progress of quantum processors and the emergence of quantum computing clouds, implementing quantum reinforcement learning algorithms utilizing parameterized quantum circuits (PQCs) on NISQ devices remains infrequent. In this work, we take the first step towards executing benchmark quantum reinforcement problems on real devices equipped with at most 136 qubits on the BAQIS Quafu quantum computing cloud. The experimental results demonstrate that the policy agents can successfully accomplish objectives under modified conditions in both the training and inference phases. Moreover, we design hardware-efficient PQC architectures in the quantum model using a multi-objective evolutionary algorithm and develop a learning algorithm that is adaptable to quantum devices. We hope that the Quafu-RL can be a guiding example to show how to realize machine learning tasks by taking advantage of quantum computers on the quantum cloud platform.
Effects of tip clearance on non-synchronous aerodynamic excitation of compressor rotor blades
Authors: Zhang Shaoping , Zhao Xing , Wang Songbai
Published: March 2024

The unstable tip flow of compressor rotor may cause the aeroelastic problems, inducing the non-synchronous vibration with high amplitude level, which has a significant effect on blade high cycle fatigue and safety. In order to investigate the effects of tip clearance on non-synchronous aerodynamic excitation of compressor rotor blades, the full annular numerical simulations were conducted for the unsteady flow field of a 1.5-stage compressor under near stall conditions. The frequency characteristics of non-synchronous aerodynamic excitation and tip unstable flow structure were analysed for different tip clearances (0.5%C, 1.0%C, 2.0%C, and 3.0%C). The results showed that the frequency and amplitude are strongly influenced by the tip clearance size. For 0.5%C tip clearance, the main frequency of non-synchronous aerodynamic excitation is the low-frequency aerodynamic excitation frequency, which is mainly caused by tornado-like vortex in the tip suction side, the dominant aerodynamic disturbance mode number is 19. For 2.0%C and 3.0%C tip clearance, the dominant aerodynamic disturbance mode number is 47, and the main aerodynamic excitation frequency is high frequency non-synchronous aerodynamic excitation frequency, mainly caused by the shedding vortices propagating circumferentially at the blade tip, exhibiting the feature of “rotating instability”.
Performance prediction and loss evaluation of the carbon dioxide supersonic nozzle considering the non-equilibrium condensation
Authors: Guojie Zhang , Yunpeng Li , Jianming Ye , Zunlong Jin , Dykas Sławomir
Published: March 2024

Carbon dioxide (CO2) is being considered as a promising working medium in energy conversion and refrigeration cycles due to its unique properties. When carbon dioxide flows with supersonic in turbo machinery (compressor), the non-equilibrium effect is enhanced due to the large change of fluid velocity, resulting in non-equilibrium condensation of the blade, which will seriously affect the performance of the compressor. Considering the similarities in flow characteristics between the nozzle and the compressor blade, the condensing flow of the blade can be predicted by simulating in a nozzle. The real gas model is used. The pressure and the nucleation rate are predicted based on the modified model, and the flow losses and thermal efficiency are analyzed in different states. The results show that the pressure variation in the nozzle aligns well with the experimental data. When the fluid transitions from subcritical to supercritical, the condensation interval decreases and the peak of the nucleation rate increases. The maximum supercooling decreases gradually. The flow losses are relatively large, and the thermal efficiency is low.
Research and application of wide and efficient hydraulic design in centrifugal pump
Authors: Wang Zhewen , Li Jiejun , Hou Duohua , Qiao Yulan , Wu Maojing
Published: March 2024

Through the analysis of the wide and efficient mechanism of centrifugal pump, this paper finds that the shape of the blade inlet angle to the outlet angle distribution line of the centrifugal pump impeller within the blade wrapping angle is the key factor determining the width and efficiency. Two sets of blade thickening laws are adopted, namely the equal thickness type and the NACA1933 air-foil. Tests have shown that the hill-type is superior Linear scheme, NACA1933 air-foil blades are superior to equal-thickness blades. The hill-type solution achieves the performance indicators of wide and efficient centrifugal pumps. Firstly, the angle distribution line of the inlet angle to the outlet angle of the pump is designed, and the calculus equation is applied to solve the conformal transformation line in the square grid, so as to produce a wide and efficient centrifugal pump impeller profile. The design method is applied to different specific speed centrifugal pumps, and the test results show that this method achieves the purpose of wide and efficient centrifugal pump, reaches the international advanced level, and provides a new method for the hydraulic design of centrifugal pump.
Influence of bionic structure on hydraulic performance and drag reduction effect of a centrifugal pump
Authors: Liu J , Zhang F , Zhu L F , Yuan S Q , Xu R H , Zhang H
Published: March 2024

Based on bionic theory, miniature dimple-type structures are constructed on the blades of a single-stage centrifugal pump to investigate the influence of the bionic structures on the hydraulic performance and drag reduction effect of the pump. The results show that dimples with shallower depth and which are located near the front section of the blade suction surfaces are more effective in improving the efficiency and reducing the drag of the pump. At small flow rate, due to the mismatch between the incoming flow angle and the blade placement angle, serious flow separation occurs in several flow channels, accompanied by the formation of the vortices, which would deteriorate the performance of the pump. With the arrangement of the dimples on blade suction surfaces, some low-speed vortices formed in the dimples, which is equivalent to increasing the effective thickness of the viscous substrate layer and decreasing the velocity gradient of the boundary layer. Therefore, the velocity distribution in the flow channels gets more uniform, and the turbulence kinetic energy and wall shear stress are thereby reduced.
Numerical investigation on cavitation performance for centrifugal pumps with different impeller inlet geometry
Authors: Zhang Z Y , Luo X W
Published: March 2024

In the centrifugal pump, cavitation often leads to the noise and pressure pulsation, further affects the performance and operation of the pump. Therefore, it is essential to improve cavitation performance at the stage of pump design. In this paper, three centrifugal pump impellers are designed by using different inlet geometry, where one is the conventional type and has cross section diffusion of flow passage along flow direction, and other two impellers are proposed and have cross section contraction of flow passage from impeller inlet to exit. For comparison of cavitation performance, the three-dimensional cavitating turbulent flows are simulated using the RANS method for the pumps. The results show that the pumps with the proposed meridional section have much better cavitation performance at design point while their hydraulic efficiency is also improved at larger flow rate, compared with that with the conventional meridional section design. Extending the blade leading edge of the proposed impeller is very helpful to obtain better cavitation performance further due to the uniform flow and smaller pressure drop around impeller inlet.
Study on unsteady characteristics of the reactor coolant pump under non-uniform inflow
Authors: Zhang Mingyu , Zhang Wenjie , Zhang Rongyong , Guo Xi’an , Zhu Rongsheng , Yuan Shouqi , Long Yun
Published: March 2024

The primary circuit of a nuclear power plant contains a steam generator (SG) and two vertical reactor coolant pumps (RCPs). Two RCPs are installed at the bottom of the SG. The structure of the channel-head of the SG is special, which leads to uneven flow from the RCP inlet and affects the operation performance of the pump. Taking the RCP of the third-generation reactor as the research object, the unsteady characteristics of the third-generation RCP under non-uniform inflow conditions were investigated using CFD, and the pressure pulsation characteristics inside the RCP were mainly studied. A series of monitoring points were set at the channel of the channel-head, impeller, diffuser and casing section respectively to study the influence of non-uniform flow on the pressure fluctuation and radial force distribution of the RCP. The results show that non-uniform inflow can cause instability in pressure fluctuations in the “throat” region of the channel-head. The interaction between the impeller and diffuser can cause pressure pulsation from the impeller outlet to the diffuser inlet, potentially impacting the safe and stable operation of the RCP. This research provides certain theoretical support for the design of RCPs under the condition of non-uniform inflow.
Comparative study of the cavitation situation and the non-cavitation situation under unsteady flow phenomena of a centrifugal pump
Authors: Nie Lun , Liu ZhuQing , Yang Wei , Li YaoJun
Published: March 2024

Numerical simulations in three dimensions, both with and without cavitation, were conducted to determine the influence of cavitation on a centrifugal pump. The reliability and accuracy of the numerical model were demonstrated through satisfactory agreement between the experimental and numerical values of the pump’s performance. An in-depth analysis of the correlation between performance characteristics and cavitation was undertaken. The research results indicate that cavity bubbles initially appear near the suction surface of the blade and gradually extend toward the middle of the blade-channel as cavitation intensifies. Moreover, based on the simulation results, it can be concluded that head characteristics are linked to the development of cavitation on the suction surface of the leading edge of the blade runner. A detailed analysis of experimental data and simulation results reveals that cavitation obstructs the flow channel and alters water flow direction, thereby diminishing operational capacity.
Numerical assessment of erosion wear in Pelton turbine injectors
Authors: Fan W R , Guo P C , Sun L G , Zheng X B
Published: March 2024

The Pelton turbine is the main type of turbine used to develop hydropower resources in high-head sections and is more sensitive to sediment erosion. To analyse the causes of asymmetric erosion distribution on the injector surface, a solid-liquid-gas three-phase numerical study of Pelton turbine injectors is carried out. The results indicate that as the sediment diameter increases, the differences in particle discharge distribution among the jets of each branch also increase, and the asymmetric erosion distribution on the injector surface becomes stronger. The particle trajectory is influenced by the vortex structure, and fine particles mainly cause banded erosion, while coarse particles cause sheet erosion. At constant inflow conditions, the particle residence time is related to erosion morphology, and the particle velocity and the number of impacts affect the erosion rate on the injector surface. It is recommended to avoid long-term operation of the turbine under conditions of excessively small or large sediment diameters and to pay attention to the sediment erosion degree of the middle branch needle and the end branch nozzle of the water supply mechanism. The research findings of this paper can provide references for further optimization of the design, operation, and maintenance of the Pelton turbine.
Effect of different draft tube designs on the phase resonance in a pump-turbine based on compressible CFD simulation
Authors: Fang Y J , Xiao Y J , Liu D M , Wang G J , Zhang J F
Published: March 2024

An investigation into projects with significant noise issues during full-load turbine operation revealed a distinct draft tube elbow design difference compared to more successful projects. This prompted an initiative to explore the impact of draft tube shape on pressure pulsations within the pump-turbine during full-load operation. Various draft tube designs were tested on the same prototype-scale pump-turbine unit using 3D compressible transient simulations. Results indicated increased pressure pulsation amplitude in the spiral casing for the flat elbow draft tube, accompanied by phase shifts that rendered pressure pulsations close to zero at certain locations, converting direct pulsations into indirect ones. Moreover, phase variations in the opposing runner channel aligned with multiples of the rotation period, suggesting possible cancellation of pressure pulsation waves. These improvements were confirmed through contour analysis, which showed reduced negative pressure areas in the draft tube, minimized pressure differences, and more uniform and stable streamlines. This study analyses the influence of draft tube shape on internal flow field pressure fluctuations, offering theoretical insights for enhancing pump turbine stability and guiding further research.
Multi-objective optimization design of aerodynamic and infrared characteristics of multi-stream serpentine nozzle
Authors: Xu Jianyu , Zhou Li , Shi Jie , Meng Yubo , Shi Jingwei , Wang Zhanxue
Published: March 2024

A multi-objective optimization design of multi-stream serpentine nozzle was carried out to improve the aerodynamic performance and reduce the infrared radiation signal. A numerical simulation was carried out to investigate the effects of nozzle pressure ratio (NPR), Aspect ratio (AR) and Ratio of length and diameter (L/D). Computational fluid dynamics (CFD) simulation was employed to study the aerodynamic performance of the multi-stream serpentine nozzle, and the narrow-band method with discrete transfer method were used to calculate its infrared radiation intensity distribution characteristics. A 3-factor, 21-level orthogonal table was designed based on the orthogonal experimental method, and multi-stream serpentine nozzle with different geometrical parameter and operating conditions were designed to obtain the aerodynamic performance and infrared radiation intensity data of each experimental sample point. Radial Basis Function (RBF) neural network and Multi-Objective Particle Swarm Optimization algorithm were used to optimize the geometry and operating conditions with better aerodynamic performance and weaker infrared signal. The result shows that the Pareto solutions obtained by the optimization have good accuracy compared with the numerical simulation results, with an aerodynamic performance error of 0.02% and an infrared radiation intensity error of 0.24%.
Influences of nozzle pressure ratio on flow characteristics of serpentine multi-stream supersonic nozzle
Authors: Meng Yubo , Shi Jingwei , Zhou Li , Zhang Yi , Wang Zhanxue
Published: March 2024

The serpentine multi-stream supersonic nozzle (SMSN) is adopted for the multi-stream exhausted system of the Adaptive Cycle Engine to enhance the stealth performance of next-generation fighter. In this paper, the effects of the nozzle pressure ratio (NPR) on the flow characteristics of the SMSN were studied using the numerical simulation method validated by experimental data. The serpentine configuration leads to the nonuniform pressure distribution. At the mixing position, the expansion and shock waves are generated due to the pressure difference. As the NPR increases, the flow separation and shock wave in the mixing section gradually weaken and disappear. The thrust coefficient rises first and then drops. Due to the flow separation under the design condition, the thrust coefficient is the largest at MPR=6 and TPR=2.272. As the MPR increases at TPR=1.893, the compression effect of the main flow is enhanced on the upper third flow. The thrust coefficient rises first and then drops, and reaches the maximum at MPR=6. As the TPR increases at MPR=5, the compression effect of the main flow is weakened on the upper third flow. The thrust coefficient rises first and then drops, and reaches the maximum at TPR=2.272.
Study on the sensitivity of steam ejector simulation to wall treatment methods
Authors: Cao Zhengqing , Fang Kaiyue , Zhang Xinchen , Yang Xuelong
Published: March 2024

Considering the importance of turbulence model and wall treatment to steam ejector simulation, the influence of five wall treatment methods on numerical results was studied based on the realizable k-ε turbulence model (RKE). Combined with experimental data and SST turbulence model, the prediction of complex flow phenomena inside the ejector, including shock wave and reflux, by different wall treatment methods is discussed. The results show that under the numerical simulation conditions, the enhanced wall treatment method (EWT) combined with the RKE model can better predict the injection coefficient of the steam ejector, and the relative error compared with the experimental data is 5.3%. The standard wall function method (STWF) ignores the influence of the viscous bottom layer, resulting in inaccurate simulation of the internal flow phenomenon of the injector, and the injection coefficient calculated by the simulation is 10.2% higher than the experimental value. The results of the non-equilibrium wall function (NWF) method are relatively indifferent to the experimental values, and are not recommended when simulating steam ejectors.
Optimized design of steam ejector primary nozzle based on orthogonal test method
Authors: Fang Kaiyue , Cao Zhengqing , Zhang Xinchen , Yang Xuelong
Published: March 2024

This paper proposes an orthogonal test method to optimize the design parameters of a steam ejector. The objective of this method is to improve the cooling system’s efficiency and effectiveness. The L9(33) orthogonal table was established to simultaneously optimize the shape curve of the converging portion of the primary nozzle, the length of the throat, and the angle of the diverging portion, and the entrainment rate and the critical backpressure were used as the performance indexes to formulate 9 groups of test schemes with a total of 108 cases, which were simulated under the same conditions. Based on Computational Fluid Dynamics (CFD) technology, the influence order of the three parameters is derived by polar analysis and the flow field is analyzed at the overall as well as the primary nozzle. The results show that the shape curve of converging portion of the primary nozzle is a sensitive factor affecting the performance of the ejector, which should be emphasized in practical production applications; the Mach number shapes at the primary nozzles of different structures show similarity and overlap at a distance of about 0.03 m from the mixing chamber. The Mach number profiles at different back pressures show want similarity.
Investigation of the film cooling performance of ceramic matrix composites plate with different braided structures
Authors: Zhu A L , Tu Z C , Mao J K , Zhao C W
Published: March 2024

The ceramic matrix composite (CMC) materials have been gradually applied in the high temperature components, due to its excellent heat resistance and mechanical performance. The CMC component still need cooling to protect its safe operation in the high temperature environment of aero engine, such as film cooling structure. This study focuses on the influence of braided structure on the film cooling effect over a three-dimensional braided CMC plate. The full-size calculation model reflecting the internal mesoscale structure of CMC plate was established. The thermal properties of fibers and matrix are also introduced in mesoscale. The geometric parameter which is braided angle of braided structure is changed in different models, to analyze its impacts on the comprehensive film cooling effect. The results show that the fiber bundles inside the CMC plate are the main heat transfer channel, due to its relatively higher thermal conductivity. The different braided angles affect the anisotropic thermal conductivity of CMC on the three main directions. There exists an optimal braided angle near 40° that maximizes the heat dissipation effect in the region near the film cooling holes. While in the downstream region away from holes, the influence of braided angle is weak.
Numerical study of the heterogeneous condensation effect on the steam turbine performance
Authors: Zhang Guojie , Wang Xiaogang , Ye Jianming , Jin Zunlong , Dykas Sławomir
Published: March 2024

The investigation of the loss and efficiency of steam turbine holds immense significance in improving the production of electric energy as a pivotal power conversion device in the electric power industry. However, during the expansion of steam in the steam turbine, the existence of heterogeneous particles leads to the heterogeneous condensation, resulting in a significant reduction in the turbine efficiency and safety of its operation. This study investigates the impact of heterogeneous condensation flow on the performance of steam turbines. First, a condensation model is developed, and numerical calculations are performed using the Bakhtar stator blade cascade. The validity of the proposed model is verified by comparing its results with existing experimental data. Then, the adiabatic flow (non-condensing), the homogeneous condensation flow, and the heterogeneous condensation flow on solid particles with a radius of 10-8[m] and particle concentration of 1015 and 1016[1/kg] are employed to investigate the effect of each flow type on steam turbine performance, and the loss, power, and efficiency in the turbine are detailedly and quantitatively calculated. The results show that in the presence of heterogeneous particles, increasing particle concentration appropriately can effectively reduce the loss caused by condensation and improve thermal efficiency.
Research on pressure-regulating device based on different combination layouts, slopes and sprinkler interval distances
Authors: Zhao Yuxia , Liu Junping , Wen Xingbin , Zhao Yanyan
Published: March 2024

To improve the water application uniformity for sprinkler irrigation on sloping land, a new type of pressure-regulating device was designed. The pressure regulation device was installed between the pipe and the inlet of the sprinkler to regulate the pressure gradient. In this study, PIPENET software was used to simulate the installation of pressure regulation device on the corresponding PY10 sprinklers and analyze the working modes of each sprinkler in the irrigation system. The simulation considered factors such as sprinkler combination layout, ground slope and sprinkler interval distance, with average application rate and uniformity coefficient as evaluation criteria. The results showed that the installation of pressure regulation device reduced the pressure difference between each sprinkler. Under these conditions, irrigation uniformity was improved. The research results indicate that integrating different sprinkler layouts, ground slopes and sprinkler interval distances significantly improved the effectiveness of pressure-regulating device installation in hilly areas. This study provided a reference for addressing poor irrigation uniformity in sloping land in hilly areas.
Leakage detection based on variational mode decomposition and long short-term memory neural network
Authors: Zheng Shumin , Yan Jianguo , Xu Yan , Li Jiang
Published: March 2024

In the process of long-term continuous operation, fluid transportation pipelines are prone to leakage accidents. Therefore, this study investigates the detection of small-sized leaks with a leakage aperture of 13 mm in pipes with a diameter of 100 mm. The experimental investigation is conducted under the following operating conditions: volume flow of 25-80 m3/h, pressure of 100-200 kPa. The variations in volume flow and pressure signals during leak occurrences are analysed. To mitigate the interference caused by noise, the variational mode decomposition (VMD) method is introduced. The VMD effectively reduces noise interference in the signals. Furthermore, the denoised signals are utilized to establish a long short-term memory neural network (LSTM). The LSTM model achieves a high accuracy rate of 91.67% for the entire dataset.
Experimental study on multiple characteristics of multi-source AE signals during cavitation process of waterjet propulsion pump
Authors: Feng Chao , Zhu Hualun , Tao Jin , Yang Mengzi
Published: March 2024

In order to investigate the cavitation-induce acoustic emission (AE) characteristics of a waterjet propulsion pump, a synchronous experimental system consisting of a test pump, a high-speed camera, and acoustic emission sensors has been established. The characteristic parameters of AE signals are extracted to established the quantitative relationships between cavitation status and AE signals. These characteristic parameters mainly consist of the ringing count rate Rc
, energy release rate Er
, and Hurst index Hi
. The cavitation status of the test pump is reflected in the characteristic parameters of the AE signals obtained by the sensors installed at different locations. The incipient blade suction side (SS) cavitation as well as the blade tip gap cavitation can be detected through the change of characteristic parameters of AE signals at impeller inlet. The start of head drop can be reflected by the variety of characteristic parameters of AE signals at impeller middle. Large-scale cavitation will lead to the breakdown of pump performance and dramatically characteristic parameters’ change of AE signals can be measured by the sensors located at impeller outlet.
Research on flow field quality measurement of super high speed circulating water channel based on LDV
Authors: Geng H H , Wang Z L , Zhu J S , Liu T Y , Zhu H L , Zou X
Published: March 2024

The flow field quality of the super high speed circulating water channel (SHSCWC) test section in the open (with a free liquid surface state) and closed (with a cavitation tunnel state) was studied. An array of flow field measuring points was established to measure the axial velocity using a laser doppler velocimeter (LDV) for both states. Meanwhile, ultrasonic sensors were used to measure the levelness of the free liquid surface in the test section. The measurement results indicated that in the open state, the non-uniformity and instability of 8 kinds of flow velocity in the flow field section are less than 1.0%, respectively, while the free liquid surface level is less than 25mm at the flow rate of 8m/s. In the closed state, the non-uniformity and instability of eight types of flow velocity in the flow field section are all below 1.0%, with turbulence being less than 0.5%. The measurement results in both states meet the requirements of technical indicators, and provide data support for the experimental research and optimal design of the SHSCWC.
Optimal flow control of vortex breakdown in a laminar swirling flow
Authors: Seifi Zeinab , Raisee Mehrdad , Cervantes Michel J
Published: March 2024

In highly swirling flows, such as hydraulic turbines operating under part-load (PL) conditions, vortex breakdown occurs and performance is impaired. Consequently, it is imperative that mitigation measures are taken. In the present study, a laminar swirling flow with a vortex breakdown at a Reynolds number of 180 is investigated. At the inlet, a swirling velocity profile with a swirl number of 1.095 is set. A stability analysis is conducted to identify unstable modes based on the assumption that vortex breakdown is a global instability. The results indicate that spiral modes with wave number 1 are unstable. An optimal flow control method based on the Adjoint method is then utilized to mitigate vortex breakdown. In the present study, the control method targets vorticity using a minimization algorithm. Control variables include radial and axial body forces. According to the results, the method was effective in mitigating vortex breakdown. A stability analysis conducted during the control process revealed that as the vorticity decreased, the growth-rate of the eigenvalue decreased, indicating that the flow is stabilized.
Reduced-order modelling of unsteady cavitating flow around a Clark-Y hydrofoil
Authors: Zhang F , Liu Y Q , Wu Q , Huang B , Wang G Y
Published: March 2024

This paper proposes a novel approach that combines Proper Orthogonal Decomposition (POD) reduced-order system with Long Short-Term Memory (LSTM) neural network to predict flow velocity. Large Eddy Simulation (LES) is used to simulate the cavitating flow around a NACA66 hydrofoil. POD is adopted to reduce the dimensionality of the high-dimensional data. It was found that 66.81% of the flow field energy and dominant coherent structures can be captured with first eight POD modes. The LSTM network model was further used to predict the temporal data of the POD mode coefficients, and the error of the predicted coefficients was within an acceptable range. The reconstructed flow field agrees well with the real flow field and the cavitation development has also been well illustrated. This method provides a promising and efficient alternative for flow prediction and has potential for applications in fluid dynamics, aerospace engineering, and hydrodynamics.
Numerical simulation of the unsteady flow mechanism and dynamic characteristics around cascade
Authors: Zhu J , Bao W C , Liu S H , Zheng H W , Zhang M D
Published: March 2024

Research on the flow mechanism and dynamic characteristics of a cascade comprising three NACA hydrofoils was conducted under varying cavitation numbers and angles of attack. This study serves as a theoretical foundation for the high-speed miniaturization of fluid machinery. Drawing upon prior findings on individual hydrofoils, comparisons were made regarding the cavitation characteristics of the cascade versus a single hydrofoil, emphasizing pressure and velocity distributions in the flow field. Results suggest that while the cascade consists of three hydrofoils, their interactions profoundly influence the flow field. The cavitation phenomena in the cascade diverge considerably from that of a single hydrofoil. Multiple hydrofoils cause a low-pressure region to appear in the middle of the cascade, making it more susceptible to cavitation flow compared to a single hydrofoil. However, interactions among the hydrofoils constrain the expansion of this low-pressure zone, rendering the cavitation flow in the cascade’s middle layer more stable. As the angle of attack rises, the cavitation flow around the cascade undergoes notable changes, with varying cavitation flows at different cascade positions. The upper layer experiences cavitation flow akin to that of a single hydrofoil. In contrast, the middle layer sustains a thin, weakly periodic cavitation flow.
Numerical simulation and experiment of a blade management device in microgravity
Authors: Chen L , Li Y , Liu J T , He X M , Qu Z , Yang N J
Published: March 2024

Currently, most satellite propulsion systems are mainly chemical propulsion, and liquid propellant is the necessary power fuel for the propulsion system. The working environment of microgravity occurs when the satellite is in orbit. According to the working characteristics of the satellite, a propellant management device of vane type is designed. The PMD is composed of a vertical guide plate and a liquid accumulator, which is applied to the propellant tank to store and manage the propellant. In this paper, the microgravity gas-liquid management and control mechanism of a propellant management device of vane type is studied by numerical simulation and tower drop test. The results of numerical simulation and tower drop test are consistent, which verifies the good fluid management characteristics of this type of propellant management device, and provides references for its engineering application and the design of this type of structure.
Design of a high-speed cavitation hydrodynamics test system
Authors: Zhang Jiayun , Yao Zhifeng , Zhong Qiang , Ren Haitao , Xiao Ruofu , Wang Fujun
Published: March 2024

Due to the high sediment content in rivers in China and the relatively high concentration of “gas core” in water, cavitation of hydraulic machinery is likely to occur at high speeds, leading to a series of problems such as reduced efficiency of hydraulic machinery, intensified vibration and material erosion. To carry out the study of cavitation erosion, a test system (hereinafter referred to as the cavitation water tunnel) suitable for the basic study of cavitation dynamics at high velocity is designed in this paper. The whole system includes a circulating loop structure, which mainly consists of a suction chamber, contraction rectifier, and test section. The test section is convenient for observing different types of cavitation flow fields inside and the highest test velocity in the test section can exceed 35 m/s. A water-gas separation chamber is designed to collect bubbles over 100 microns to ensure that the inlet of the test section is not affected by cavitation. The functions of the test system include basic experiments such as flow field characteristics, cavitation dynamics, acoustic characteristics, and cavitation erosion characteristics around hydrofoils/blades, which can provide test conditions for the study of high-speed hydrodynamic characteristics such as pumps/turbines, propellers and underwater vehicles.