Characterization of the airflow field in the rotor spinning unit based on a novel experimental approach and numerical simulation

2020 ◽  
pp. 004051752095740
Author(s):  
Qianqian Shi ◽  
Nicholus Tayari Akankwasa ◽  
Yuze Zhang ◽  
Jiang Wang ◽  
Jun Wang ◽  
...  
Keyword(s):  
High Speed ◽  
Experimental Approach ◽  
Operating Conditions ◽  
Air Pressure ◽  
Rotor Spinning ◽  
Model Unit ◽  
Transfer Channel ◽  
Rotor Wall ◽  
Airflow Field ◽  
Fundamental Research

It is very challenging to experimentally characterize and verify the airflow in the rotor spinning machine because the process takes place in an enclosure. In an attempt to portray the process, we present a methodology that combines a novel experimental approach and numerical techniques. We developed a model unit and used colored smoke to mimic the airflow behavior practically, measured the air pressure, and compared the results to the simulation data. Three state conditions, namely suction and rotation (the regular rotor spinning operation, (Case 1)), without rotation (Case 2), and without suction (Case 3), were adopted to investigate the formation mechanism of the airflow field in the rotor spinning unit based on two operating conditions. Results show that, in a regular state, the airstream accelerates rapidly in the transfer channel under the dominant action of air suction at the rotor outlet and crashes clockwise to the rotor wall with the joint action of two operating conditions. In the rotor, the airflow flows clockwise with the velocity distribution of a multi-ring gradient due to the dominant action of high-speed rotor rotation. Analytics from the air pressure indicate that while the air pressure in the rotor is mainly controlled by the action of the air suction mechanism, it is also affected by the superposition action of the rotation mechanism. This approach is groundbreaking for rotor spinning machine optimization and is anticipated to trigger more insights that will lead to fundamental research in the spinning industry and beyond.

Effect of position of the fiber transport channel on fiber motion in the high-speed rotor

2021 ◽  
pp. 004051752110018
Author(s):  
Rui Hua Yang ◽  
Chuang He ◽  
Bo Pan ◽  
Hongxiu Zhong ◽  
Cundong Xu
Keyword(s):  
High Speed ◽  
Channel Model ◽  
Three Dimensional ◽  
Discrete Phase Model ◽  
Transport Channel ◽  
Rotor Spinning ◽  
Fiber Motion ◽  
Discrete Phase ◽  
Airflow Field ◽  
Fiber Transport

The task of the fiber transport channel (FTC) is to transport the fibers from the carding roller to the rotor. Its geometric position in the spinning machine has a strong influence on the characteristics of the airflow field and the trajectory of the fiber motion in both the rotor and the FTC. In this paper, a three-dimensional pumping rotor spinning channel model was established using ANSYS-ICEM-CFD software with three different positions of the FTC (positions a–c). Further, the simulations of air distribution were performed using Fluent software. In addition, the discrete phase model was used to fit the fiber motion trajectory in the rotor. The simulation results showed that among the three types of FTC, position b is the optimal condition. The gradients of airflow velocity in the channel at position b were greater than those of the other two positions, which is conducive to straightening of the fiber.

Comparison of the airflow characteristics and yarn properties between conventional and dual-feed-opening rotor spinning units

2021 ◽  
pp. 004051752110417
Author(s):  
Qianqian Shi ◽  
Jiang Wang ◽  
Yuze Zhang ◽  
Qian Ding ◽  
Nicholus Tayari Akankwasa ◽  
...  
Keyword(s):  
Field Distribution ◽  
Air Pressure ◽  
Dynamics Simulation ◽  
Superior Performance ◽  
Rotor Spinning ◽  
Future Design ◽  
Yarn Properties ◽  
Spun Yarns ◽  
Airflow Field ◽  
Fancy Yarns

In order to explore the differences between conventional and dual-feed-opening rotor spinning units (RSUs), this work compares the airflow characteristics of two RSU models utilizing a computational fluid dynamics simulation model with the accuracy verified by airflow behavior observation and air pressure measurement. The effect of two different opening roller speeds on the airflow field distribution of a dual-feed-opening model is also investigated. In addition, the yarn properties of six pure and blended yarns corresponding to the two RSU models are evaluated. The results reveal that the distributions of airflow velocity vector and air pressure in the two RSU models show a strong similarity under the same boundary conditions. However, the dual-feed-opening model possesses a centrosymmetric and more balanced airflow field distribution compared to the conventional model. In addition, the dual-feed-opening yarns show a superior performance in comparison to the conventional yarns. Furthermore, for the dual-feed-opening model, there are equivalent contributions of two separated opening and fiber transmission systems to the airflow field distribution and yarn formation. Compared to the configuration with the same two opening roller speeds, the dual-feed-opening model configured with two different opening roller speeds obtains an improved blended yarn performance with having few effects on the airflow characteristics. This strength of the dual-feed-opening RSU could facilitate the production of blended and fancy yarns employing the fibers with diverse properties. This study could provide some guidelines for the manufacture of rotor-spun yarns and the future design of RSUs.

scholarly journals Efficiency of disengaged wet brake packs

2018 ◽  
Vol 233 (6) ◽  
pp. 1562-1569 ◽  
Author(s):  
M Leighton ◽  
Nicholas Morris ◽  
Gareth Trimmer ◽  
Paul D King ◽  
Homer Rahnejat
Keyword(s):  
High Speed ◽  
Experimental Approach ◽  
Fuel Efficiency ◽  
Operating Conditions ◽  
Squeeze Film ◽  
Navier Stokes ◽  
Fluid Viscosity ◽  
Fluid Inertia ◽  
Systems Model ◽  
High Fluid

Key objectives in off-highway vehicular powertrain development are fuel efficiency and environmental protection. As a result, palliative measures are made to reduce parasitic frictional losses while sustaining machine operational performance and reliability. A potential key contributor to the overall power loss is the rotation of disengaged wet multi-plate pack brake friction. Despite the numerous advantages of wet brake pack design, during high-speed manoeuvre in highway travel or at start-up conditions, significant frictional power losses occur. The addition of recessed grooves on the brake friction lining is used to dissipate heat during engagement. These complicate the prediction of performance of the system, particularly when disengaged. To characterise the losses produced by these components, a combined numerical and experimental approach is required. This paper presents a Reynolds-based numerical model including the effect of fluid inertia and squeeze film transience for prediction of performance of wet brake systems. Model predictions are compared with very detailed combined Navier–Stokes and Rayleigh-Plesset fluid dynamics analysis to ascertain its degree of conformity to representative physical operating conditions, as well the use of a developed experimental rig. The combined numerical and experimental approach is used to predict significant losses produced during various operating conditions. It is shown that cavitation becomes significant at low temperatures due to micro-hydrodynamic action, enhanced by high fluid viscosity. The magnitude of the losses for these components under various operating conditions is presented. The combined numerical-experimental study of wet multi-plate brakes of off-highway vehicles with cavitation flow dynamics has not hitherto been reported in the literature.

scholarly journals Flow Structures Inside a Rotor-Stator Cavity

2001 ◽  
Vol 7 (4) ◽  
pp. 285-300 ◽  
Author(s):  
T. Geis ◽  
J. Ebner ◽  
S. Kim ◽  
S. Wittig
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Operating Conditions ◽  
Speed Test ◽  
Cooling Flow ◽  
Moment Coefficient ◽  
Rotor Wall ◽  
Threedimensional Flow ◽  
Temperature Levels ◽  
Aero Engines

This paper describes an experimental investigation initiated to determine the threedimensional flow field inside the rim seal cavity of a double-shrouded rotor-stator system. Thereby, the effects caused by perturbances in the rotor wall were additionally examined. The objective of this work is to provide detailed information about the mechanisms that can promote elevated temperature levels in the high pressure section of a gas turbine. Both ingested hot gas and windage heating generated at the rotor-stator interface can severely affect the material temperatures and thus considerably increase the thermal load of the rotating parts.The flow velocities were measured by means of an advanced LDV system capable of providing phase-resolved data. The flow field was determined for two different rotorstator combinations. One of the rotor disks contained small rectangular cavities, located at the disk rim and arranged uniformly in’ the circumferential direction. These elements are referred to as the shank cavities of the rotor disk.The mechanical torque was measured to demonstrate the influence of these elements on the windage power. The measurements were performed at operating conditions that are typical for aero-engines. It is shown that a perturbed rotor surface can raise the drag notably. The experiments were conducted in a high speed test rig at rotational Reynolds numbers up toReϕ≈4.2*106. The data were plotted as the dimensionless moment coefficientcMand correlated withReϕand the dimensionless cooling flow ratecw.

Assessment of Pressure Oscillations Delivery to the Lung

2011 ◽  
Author(s):  
A. M. Al-Jumaily ◽  
P. Reddy ◽  
J. Mussa
Keyword(s):  
Theoretical Model ◽  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Pressure Wave ◽  
Experimental Approach ◽  
Distress Syndrome ◽  
Operating Conditions ◽  
Air Pressure ◽  
Pressure Oscillations

Pressure wave oscillations are used in the treatment of several respiratory ailments such respiratory distress syndrome. A theoretical model and experimental approach are used to quantify the level of delivery of air pressure oscillations applied at the mouth to various parts of the lung. Both approaches indicate that these oscillations can be delivered with specific frequencies and magnitudes deep in the lung and under specific operating conditions.

Influence of the air pressure and oil amount to the temperature of the high-speed bearings lubricated by oil mist

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Miloš Stanković ◽  
Nenad Kolarević ◽  
Nikola Davidovic ◽  
Marko Miloš
Keyword(s):  
High Speed ◽  
Design Methodology ◽  
Experimental Approach ◽  
Air Pressure ◽  
Jet Engine ◽  
Content Type ◽  
Custom Made ◽  
Bearing Assembly ◽  
Oil Mist ◽  
Lubrication Conditions

Purpose The purpose of this paper is to improve the lubrication and remove as much as possible of the heat generated in the bearing assembly, embedded in the jet engine. Design/methodology/approach To determine the necessary values of the air pressure and oil amount, an experimental approach is used. For that purpose, a custom made test rig is developed. Findings Less amount of oil makes better lubrication conditions, reflected in the smaller temperature of the bearings. Concerning the air pressure, too high and too low air pressure deteriorates the lubrication parameters. An optimum value should be determined experimentally. The influence of oil amount is remarkably bigger than the influence of air pressure. Originality/value This experimental investigation provides an easy and fast way to improve the high-speed bearings lubrication parameters.

Iterative learning control of air pressure variation inside a high-speed train under the excitation of the tunnel pressure wave with a fixed-morphologic form

2021 ◽  
pp. 095440972110327
Author(s):  
Zhiying He ◽  
Chunjun Chen ◽  
Dongwei Wang ◽  
Chao Deng ◽  
Jia Hu ◽  
...  
Keyword(s):  
Iterative Learning Control ◽  
Pressure Wave ◽  
High Speed ◽  
Learning Control ◽  
Pressure Variation ◽  
Iterative Learning ◽  
Air Pressure ◽  
High Speed Train ◽  
Comfort Index ◽  
Simulation Signal

Based on the characteristics that the tunnel pressure wave has a fixed-morphologic form when the same train passes through the same tunnel, an applicational approach based on the iterative learning control (ILC) is developed, aiming at overcoming the drawbacks of the traditional strategy for controlling the air pressure variation inside a high-speed train carriage. To achieve the goal, the control system is mathematically modelled. Then, the problem is formulated. The task of suppressing the influence of the tunnel pressure wave on the air pressure inside the carriages is shifted as an ILC problem of tracking the comfort index with varying trial length. The algorithm of refreshing the control signal from trial to trial is determined and the process of ILC control is designed. Next, the convergence of the newly-developed applicational ILC algorithm is discussed and the algorithm is simulated by the simulation signal and field-test signal. Results show that the applicational ILC algorithm be more adaptable in handling the control of the air pressure inside carriage under the excitation of varying-amplitude, varying-scale and varying-initial-states tunnel pressure wave. Meanwhile, the matching with tunnel pressure wave makes the applicational ILC algorithm will take both the riding comfort and fresh air into consideration, which upgrades the performances when the high-speed train passing through long tunnels.

scholarly journals Experimental performance comparison between circular and elliptical tubes in evaporative condensers

2021 ◽  
Author(s):  
Giuseppe Starace ◽  
Lorenzo Falcicchia ◽  
Pierpaolo Panico ◽  
Maria Fiorentino ◽  
Gianpiero Colangelo
Keyword(s):  
Heat Transfer ◽  
Experimental Approach ◽  
Fluid Dynamic ◽  
Major Axis ◽  
Performance Comparison ◽  
Operating Conditions ◽  
Condensation Temperature ◽  
Air Cooled Condensers ◽  
Reduced Scale ◽  
Dynamic Phenomena

AbstractIn refrigeration systems, evaporative condensers have two main advantages compared to other condensation heat exchangers: They operate at lower condensation temperature than traditional air-cooled condensers and require a lower quantity of water and pumping power compared to evaporative towers. The heat and mass transfer that occur on tube batteries are difficult to study. The aim of this work is to apply an experimental approach to investigate the performance of an evaporative condenser on a reduced scale by means of a test bench, consisting of a transparent duct with a rectangular test section in which electric heaters, inside elliptical pipes (major axis 32 mm, minor axis 23 mm), simulate the presence of the refrigerant during condensation. By keeping the water conditions fixed and constant, the operating conditions of the air and the inclination of the heat transfer geometry were varied, and this allowed to carry out a sensitivity analysis, depending on some of the main parameters that influence the thermo-fluid dynamic phenomena, as well as a performance comparison. The results showed that the heat transfer increases with the tube surface exposed directly to the air as a result of the increase in their inclination, that has been varied in the range 0–20°. For the investigated conditions, the average increase, resulting by the inclination, is 28%.

scholarly journals High-Speed Elevator Car Air Pressure Compensation Method Based on Coupling Analysis of Internal and External Flow Fields

2021 ◽  
Vol 11 (4) ◽  
pp. 1700
Author(s):  
Lemiao Qiu ◽  
Huifang Zhou ◽  
Zili Wang ◽  
Shuyou Zhang ◽  
Lichun Zhang ◽  
...  
Keyword(s):  
Pressure Fluctuation ◽  
Iterative Learning Control ◽  
High Speed ◽  
Learning Control ◽  
Flow Fields ◽  
External Flow ◽  
Iterative Learning ◽  
Air Pressure ◽  
Coupling Analysis ◽  
Pressure Compensation

As the demand for high-speed elevators grows, the requirements of elevator performance have also developed. The high speed will produce strong airflow disturbances and drastic pressure changes, which is prone to cause passenger discomfort. In this paper, an elevator car air pressure compensation method based on coupling analysis of internal and external flow fields (IE-FF) is proposed. It helps to adaptively track the ideal air pressure curve (IAPC) inside the car and controls the air pressure fluctuation to improve the ride comfort of the elevator. To obtain the air pressure transient value in the elevator car, an IE-FF modeling method is proposed. Based on the IE-FF model, the air pressure compensation system is developed. To realize the air pressure compensation inside the car, an adaptive iterative learning control (A-ILC) algorithm is proposed, to eliminate the passengers’ ear pressing due to the severe air pressure fluctuation. To verify the proposed method, the KLK2 (Canny Elevator Co., Ltd., 2015, Suzhou, China) high-speed elevator is applied. The numerical experiment results show that the proposed method has higher tracking accuracy and convergence speed compared to the classical Proportion Integral Differential (PID) algorithm and the Proportion Integral-iterative learning control (PD-ILC) algorithm.

Sign in / Sign up

Export Citation Format

Share Document