scholarly journals Effects of plate wear on bar forces and fiber properties in a mill scale LC-refiner

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Matthias Aigner ◽  
James Olson ◽  
Yu Sun ◽  
Peter Wild
Keyword(s):  
Leading Edge ◽  
Force Sensor ◽  
Compression Force ◽  
Mill Scale ◽  
Time To Peak ◽  
Early Peak ◽  
Run Time ◽  
The Time Domain ◽  
The Individual ◽  
Force Profiles

Abstract A set of piezo electric force sensors is implemented in a 52-inch mill-scale low consistency refiner to explore the effect of refiner plate wear on bar force sensor measurements. The sensor replaces a short length of a stator bar and measures normal and shear forces applied during the passage of each rotor bar. In previous work with this type of force sensor, force profiles for individual bar passing events (BPE) were investigated. In the work presented here, force profiles for individual BPEs are identified based on key features in the time domain force data. The individual bar force profiles are classified as single peak events which feature one peak corresponding to the fiber compression force and as dual peak events corresponding to fiber compression force and the corner force. The bar passing events are then analysed, based on dual peak ratio and time to peak of the early peak in the dual peak events. Force measurements are evaluated over the full run time of a set of refiner plates. Findings are compared with refiner plate wear measurements and discharge fiber analysis. It is shown that the decrease in the prevalence of the corner force correlates with the wear of the leading edge of the refiner bars or bar rounding of the run time of the refiner plate. This is accompanied by a decrease in plate performance which is represented by a decrease in fiber length and freeness reduction for the same refiner load.

Measurement and interpretation of spatially registered bar-forces in LC refining

2020 ◽  
Vol 35 (4) ◽  
pp. 600-610
Author(s):  
Matthias Aigner ◽  
James Olson ◽  
Peter Wild
Keyword(s):  
Work Force ◽  
Force Sensor ◽  
Edge Length ◽  
Rotary Encoder ◽  
Critical Gap ◽  
Early Peak ◽  
Geometric Variables ◽  
Force Data ◽  
Force Profiles ◽  
Shed Light

AbstractA high resolution rotary encoder and a piezo electric force sensor are implemented in a 16-inch laboratory-scale low consistency refiner to explore the effect of plate gaps on bar-force profiles. The sensor replaces a short length of a stator bar and measures normal and shear forces applied during the passage of each rotor bar. The rotary encoder data is used to locate the rotor bars relative to the stator bar in which the sensor is located. Previous work with this type of force sensor focuses primarily on the distribution of the maximum force measured during the passage of each rotor bar over the sensor or bar passing event, BPE. In this work, force profiles for bar passing events are registered to the position of rotor bars relative to the stator bar in which the sensor is located. These registered force profiles are measured for a range of plate gaps and two different pulp furnishes. The angular reference provided by the encoder makes it possible to generate mean force profiles. As force data for individual BPEs is highly variable, these mean force profiles have potential to shed light on the fundamental mechanisms of mechanical refining. For large gaps, there is a late peak in the force profiles that occurs toward the end of the bar passing event. For gaps that are less than the critical gap, below which fiber cutting occurs, there is an early peak in the force profiles that occurs at the start of the bar passing event. It is hypothesized that the early peak represents the corner force and, therefore, that corner force is causal in the onset of fiber cutting. To explore this hypothesis, a model is presented connecting corner force and friction force to the progression geometric variables during the bar passing event such as the bar edge length engaged at any point in the bar passing event and the area covered by the rotor bar on the force sensor at any point in the bar passing event.

Power–gap relationships in low consistency refining

2019 ◽  
Vol 34 (1) ◽  
pp. 36-45 ◽  
Author(s):  
Jorge Enrique Rubiano Berna ◽  
Mark Martinez ◽  
James Olson
Keyword(s):  
Experimental Data ◽  
Force Sensor ◽  
Pilot Scale ◽  
Mill Scale ◽  
Control Power ◽  
Wide Range ◽  
Theoretical Assumptions ◽  
Mechanical Pulps ◽  
The Relationship ◽  
Good Agreement

Abstract Distance between stationary and rotating refining plates, gap, has a direct and significant impact on refining power. Gap is almost universally used to control power in low consistency refining operations. The relationship between power and gap are affected by refiner size, pulp type, plate pattern and refining conditions. In this study, a correlation was developed to describe the power–gap relationships at a wide range of refining conditions and furnish. The correlation was developed using pilot-scale refining data of mechanical pulps. Results showed that a properly defined dimensionless power number is suitable to describe refining power as well as to compare different refiners under the same grounds. The developed correlation was also used to predict mill-scale refining data showing good agreement with between predicted and measured values. Finally, experimental data from force sensor measurements supports the correlation’s theoretical assumptions.

Using Linear Superposition to Solve Multiple Heat Source Transient Thermal Problems

2007 ◽  
Author(s):  
David T. Billings ◽  
Roger P. Stout
Keyword(s):  
Heat Source ◽  
Transient Response ◽  
Response Curves ◽  
Linear Superposition ◽  
Circuit Simulator ◽  
Set Up ◽  
The Time Domain ◽  
The Individual ◽  
Transient Thermal ◽  
Application Engineer

For many years engineers have been using linear superposition to solve steady state thermal problems with multiple-heat-source systems. Predicting transient response of single-heat-source systems has been performed using R-C Foster networks with reasonable success. In most real applications there are multiple heat sources that are interacting perhaps in very complex ways in the time domain. Being able to simulate these interactions using a spreadsheet tool or a circuit simulator may be very advantageous to a device or application engineer designing or evaluating an application design. Using an RC-network model of a system to represent the individual transient response curves, we’ll show how to do this bookkeeping (and all the other calculations) for a simple system using Microsoft Excel. We’ll also see how to set up this sort of problem in a circuit simulator.

A Comparison of Two Fan Stage Designs With Different Rotor Leading Edge Sweep

2014 ◽  
Author(s):  
John Gunaraj ◽  
David Hanson ◽  
Jeffrey Hayes ◽  
Heath Lorzel ◽  
Nick Nolcheff ◽  
...  
Keyword(s):  
Pressure Ratio ◽  
Stability Margin ◽  
Leading Edge ◽  
Flow Capacity ◽  
Numerical Predictions ◽  
Performance Trends ◽  
Ansys Cfx ◽  
Significant Difference ◽  
Total Temperature ◽  
The Individual

Two modern single-stage fans have been designed to meet the same set of performance objectives. The most significant difference between the two designs is the fan rotor leading edge sweep. The baseline rotor has a moderately aft swept leading edge while the redesigned rotor has a more complex sweep distribution, including moderate forward sweep in the tip region. Each stage consists of the fan rotor, full span stator, and split mid-frame, and is designed for a medium bypass ratio turbofan application. The stator and the mid-frame are identical for the two configurations. The primary purpose of this study is to validate the CFD methodology, in this case a steady ANSYS-CFX approach, to predict the fan stage performance at the operating point at two tested speeds and also to predict the stalling throttle condition. Numerical predictions and engine test results are presented and show good agreement. These predicted results are compared with high quality test data including thorough measurements of total pressure and total temperature at both the rotor and stator exits allowing for a detailed understanding and comparison of the individual blade row performance. The analytical model identifies the key performance trends, including an increase in flow capacity and stability margin with equivalent stage pressure ratio and efficiency for the redesigned fan relative to the baseline.

Force Characteristics for Fine Deformation of CMC Touch Sensor and Estimation of Force Variance Using Hybrid Tactile Sensor System

2012 ◽  
Vol 24 (3) ◽  
pp. 423-429
Author(s):  
Takuya Kawamura ◽  
◽  
Ko Nejigane ◽  
Kazuo Tani ◽  
Hironao Yamada
Keyword(s):  
Tactile Sensor ◽  
Force Sensor ◽  
Sensor System ◽  
Compression Force ◽  
Sensor Element ◽  
Silicon Rubber ◽  
Touch Sensor ◽  
Slight Movement ◽  
Force Characteristics

Having previously proposed a hybrid tactile sensor system consisting of a Carbon Micro-Coil (CMC) touch sensor and a force sensor, the authors have been developing a method of measuring deformation of micrometer order, force variance of 10 gram order, and compression force when an object touches a sensor element and moves slightly. In this paper, to measure the force variance for deformation of several micrometers using the CMC touch sensor, the force characteristics of the CMC touch sensor are investigated. The CMC sensor element is made of silicon rubber containing CMCs several micrometers in diameter. It is considered that the sensor element constitutes an LCR circuit, and the CMC touch sensor, deformed mechanically, produces signals due to the modification of the circuit. In the experiment detailed in this paper, to clarify the characteristics of the CMC sensor with respect to the parameters of force and deformation, the outputs of the CMC sensor and the force sensor for deformation in the range of 1 to 9 µm are sampled. As a result, it is found that the force characteristics of the CMC touch sensor are almost linear in terms of force variance within the range of 0 to 1 N, regardless of a compression force of less than 3 N. Finally, to evaluate the performance of the sensor system, force variance for a slight movement of an object touching the sensor element is estimated in an experiment.

Aerodynamic Performance of Turbine Center Frames With Purge Flows—Part I: The Influence of Turbine Purge Flow Rates

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Stefan Zerobin ◽  
Andreas Peters ◽  
Sabine Bauinger ◽  
Ashwini Bhadravati Ramesh ◽  
Michael Steiner ◽  
...  
Keyword(s):  
Measurement Data ◽  
Leading Edge ◽  
Aerodynamic Performance ◽  
Flow Structures ◽  
Flow Rates ◽  
Purge Flow ◽  
Mass Flows ◽  
The Individual ◽  
The Impact ◽  
First Time

This two-part paper deals with the influence of high-pressure turbine (HPT) purge flows on the aerodynamic performance of turbine center frames (TCF). Measurements were carried out in a product-representative one and a half-stage turbine test setup. Four individual purge mass flows differing in flow rate, pressure, and temperature were injected through the hub and tip, forward and aft cavities of the unshrouded HPT rotor. Two TCF designs, equipped with nonturning struts, were tested and compared. In this first part of the paper, the influence of different purge flow rates (PFR) is discussed, while in the second part of the paper, the impact of the individual hub and tip purge flows on the TCF aerodynamics is investigated. The acquired measurement data illustrate that the interaction of the ejected purge flow with the main flow enhances the secondary flow structures through the TCF duct. Depending on the PFR, the radial migration of purge air onto the strut surfaces directly impacts the loss behavior of the duct. The losses associated with the flow close to the struts and in the strut wakes are highly dependent on the relative position between the HPT vane and the strut leading edge (LE), as well as the interaction between vane wake and ejected purge flow. This first-time experimental assessment demonstrates that a reduction in the purge air requirement benefits the engine system performance by lowering the TCF total pressure loss.

scholarly journals CFD DEM Analysis of a Dry Powder Inhaler

2019 ◽  
Author(s):  
Antara Badhan ◽  
V. M. Krushnarao Kotteda ◽  
Vinod Kumar
Keyword(s):  
Sensitivity Analysis ◽  
High Performance ◽  
Dry Powder Inhaler ◽  
Leading Edge ◽  
Active Pharmaceutical Ingredient ◽  
Department Of Energy ◽  
Discrete Element Modeling ◽  
Dry Powder ◽  
Throat Region ◽  
The Individual

Abstract Dry powder inhalers (DPIs), used as a means for pulmonary drug delivery, typically contain a combination of active pharmaceutical ingredient (API) and significantly larger carrier particles. The micro-sized drug particles — which have a strong propensity to aggregate and poor aerosolization performance — mixed with significantly large carrier particles that are unable to penetrate the mouth-throat region to deagglomerate and entrain the smaller API particles in the inhaled airflow. The performance of a DPI, therefore, depends on entrainment the carrier-API combination particles and the time and thoroughness of the deagglomeration of the individual API particles from the carrier particles. Since DPI particle transport is significantly affected by particle-particle interactions, very different particles sizes and shapes, various forces including electrostatic and van der Waals forces, they present significant challenges to Computational Fluid Dynamics (CFD) modelers to model regional lung deposition from a DPI. In the current work, we present a novel high fidelity CFD discrete element modeling (CFD-DEM) and sensitivity analysis framework for predicting the transport of DPI carrier and API particles. The work integrates exascale capable CFD-DEM and sensitivity analysis capabilities by leveraging the Department of Energy (DOE) laboratories libraries: Multiphase Flow Interface Flow Exchange (MFiX) for CFD-DEM, and Trilinos for leading-edge portable/scalable linear algebra. We carried out a sensitivity analysis of various formulation properties and their effects on particle size distribution with Dakota, an open source software designed to exploit High-Performance Computing (HPC) capabilities of a massively parallel supercomputer. We developed wrappers to exchange information among these state-of-the-art tools for DPI.

scholarly journals A method for image-guided positioning of cochlear specimens in insertion test benches using 3D printed stands

2021 ◽  
Vol 7 (2) ◽  
pp. 105-108
Author(s):  
Thomas S. Rau ◽  
Jakob Cramer ◽  
M. Geraldine Zuniga ◽  
Georg Böttcher ◽  
Thomas Lenarz
Keyword(s):  
Ex Vivo ◽  
Electrode Array ◽  
Force Sensor ◽  
Rigid Fixation ◽  
Image Guided ◽  
Specimen Holder ◽  
Individual Specimen ◽  
3D Printed ◽  
Parametric Cad ◽  
The Individual

Abstract Cochlear implants include an electrode array (EA) which needs to be inserted into the cochlea. Insertion tests using artificial cochlear models (ACM) or ex vivo specimens are widely used methods during EA development to characterize EA design properties, including insertion forces. Measured forces are directly linked to the orientation of the cochlear lumen with respect to the insertion axis of the test bench. While desired insertion directions in ACM experiments can be predefined by design, specimens are individually shaped and the cochlear lumen is embedded invisibly. Therefore, a new method for accurate, individual specimen positioning is required. A key element of the proposed method is a customizable pose setting adapter (PSA) used to adjust the specimen’s fine positioning. After rigid fixation of the specimen to a holder featuring spherical registration markers and subsequent cone beam computed tomography the desired insertion direction is planned. The planned data is used to calculate the individual shape of the PSA. Finally, the PSA is 3D printed and mounted between force sensor and specimen holder to correctly align the specimen to the test bench’s insertion axis. All necessary hard- and software have been developed including the specimen holder, a software for registration and trajectory planning, and a custom Matlab script whose output drives a parametric CAD file of the PSA. Positioning accuracy was determined in a first trial using 10 virtual trajectories and was found to be 0.23 ± 0.12 mm and 0.38 ± 0.17°. The presented stereotactic positioning procedure enables high repeatability in future ex vivo insertion experiments due to accurate, image-guided control of the insertion direction.

Indications of the onset of fiber cutting in low consistency refining using a refiner force sensor: The effect of pulp furnish

2018 ◽  
Vol 33 (1) ◽  
pp. 58-68 ◽  
Author(s):  
R. Harirforoush ◽  
J. Olson ◽  
P. Wild
Keyword(s):  
Fiber Quality ◽  
Force Sensor ◽  
Strength Properties ◽  
Thermomechanical Pulp ◽  
Pulp Fibers ◽  
Increase Energy Efficiency ◽  
Time Domain Signal ◽  
Softwood Kraft Pulp ◽  
The Time Domain ◽  
Process Detection

Abstract Detection of the onset of fiber cutting is beneficial in low consistency refining as it may prevent reduction of average fiber length, optimize fiber quality improvements by operating at gaps just wider than the critical gap, avoid decreasing the strength properties of paper, and increase energy efficiency. The objective of this study is to understand the effect of pulp furnish on measured bar forces and, more specifically, on the detection of fiber cutting. Bar forces, i. e. forces applied to pulp fibers by the refiner bars, are measured with a custom-designed piezoelectric force sensor. Trials were conducted with an AIKAWA 16-in. single-disc refiner using hemlock/balsam softwood thermomechanical pulp, SPF softwood thermomechanical pulp, northern bleached softwood kraft pulp, and aspen hardwood thermomechanical pulp at 3.0 to 3.5 % consistency at rotational speeds of 1200 and 1400 rpm. The power of the time domain signal of the measured forces is introduced as an indicator of the onset of fiber cutting. Our results show that this new fiber cutting metric is a sensitive and reliable metric for determination of fibre cutting for a range of pulp furnishes. The study suggests that the refiner force sensor has potential to be exploited for in-process detection of fiber cutting.

Vortex force of an impulsively started plate at high angle of attack

2017 ◽  
Vol 27 (11) ◽  
pp. 2402-2414
Author(s):  
Xiang Fu ◽  
Gaohua Li ◽  
Fuxin Wang
Keyword(s):  
Aerodynamic Force ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Aerodynamic Forces ◽  
Total Drag ◽  
Content Type ◽  
Vortical Structures ◽  
Edge Vortex ◽  
The Individual ◽  
Practical Implications

Purpose A quantitative study that can identify the primary aerodynamic forces and relate them to individual vortical structures is lacking. The paper aims to clarify the quantitative relationships between the aerodynamic forces and vortical structures. Design/methodology/approach The various contributions to the aerodynamic forces on the two-dimensional impulsively started plate are investigated from the perspective of the vorticity moment theorem. The angles of attacks are set to 45°, 58.5° and 72°, while the Reynolds number is 10,000 based on the chord length. Compared with the traditional pressure force analysis, this theorem not only tells us the total aerodynamic force during the motion, but also enables us to quantify the forces contributed from the fluid elements with non-zero vorticity. Findings It is found that the time-dependent force behaviors are dominated by the formations and evolutions of these vortical structures. The analysis of the time-averaged forces demonstrates that the lift contributed from the leading edge vortex (LEV) is nearly four times larger than the total lift and the drag contributed from the starting vortex (SV) is almost equal to the total drag when the angle of attack (AoA) increases to 72°, which means the LEV is “lift structure” whereas the SV is “drag structure”. Practical implications The present method provides a better perspective for flow control and drag reduction by relating the forces directly to the individual vorticity structures. Originality/value In this paper, the Vorticity Moment Theory is first used to study the quantitative relationships between the aerodynamic forces and the vortices.

Sign in / Sign up

Export Citation Format

Share Document