A Statistical Study of Process Variables to Optimize a High Speed Curtain Coater-Part II

TAPPI Journal ◽  
2009 ◽  
Vol 8 (2) ◽  
pp. 29-32
Author(s):  
PEEYUSH TRIPATHI ◽  
MARGARET JOYCE ◽  
PAUL D. FLEMING ◽  
MASAHIRO SUGIHARA
Keyword(s):  
Boundary Layer ◽  
High Speed ◽  
Second Phase ◽  
Substitution System ◽  
Set Up ◽  
The Stability ◽  
Air Removal ◽  
Coating Formulation ◽  
Removal System ◽  
Coating Rheology

In Part I of this work, we identified four important process, base sheet, and formulation variables that strongly influence the runnability of a curtain coater at high speed, using a Taguchi orthogonal array experimen-tal design approach. The effects identified are base sheet roughness, coating rheology, curtain height, and the amount of steam applied in the boundary layer air removal system (steam substitution system [SSS]). In the second phase of our study, we examine the contribution of these four variables on curtain coating stability in more depth using a D-optimal design of experiment. The results show the set-up of the boundary layer air removal system to be the most critical variable to maintaining the stability of the curtain. We found base sheet roughness, in combination with the parameters of the coating formulation, to also be very important. Coating coverage improved with the smoothness of the base sheet and excellent coating coverage was attainable at low coat weights. A shear thinning coating was found to provide the most favorable coating rheology for curtain stability at high speeds.

A Statistical Study of Process Variables to Optimize a High Speed Curtain Coater: Part I

TAPPI Journal ◽  
2009 ◽  
Vol 8 (1) ◽  
pp. 20-26 ◽  
Author(s):  
PEEYUSH TRIPATHI ◽  
MARGARET JOYCE ◽  
PAUL D. FLEMING ◽  
MASAHIRO SUGIHARA
Keyword(s):  
Boundary Layer ◽  
Experimental Design ◽  
High Speed ◽  
Statistical Study ◽  
Process Variables ◽  
High Speeds ◽  
The Stability ◽  
Air Removal ◽  
Removal System

Using an experimental design approach, researchers altered process parameters and material prop-erties to stabilize the curtain of a pilot curtain coater at high speeds. Part I of this paper identifies the four significant variables that influence curtain stability. The boundary layer air removal system was critical to the stability of the curtain and base sheet roughness was found to be very important. A shear thinning coating rheology and higher curtain heights improved the curtain stability at high speeds. The sizing of the base sheet affected coverage and cur-tain stability because of its effect on base sheet wettability. The role of surfactant was inconclusive. Part II of this paper will report on further optimization of curtain stability with these four variables using a D-optimal partial-facto-rial design.

Transition of streamwise streaks in zero-pressure-gradient boundary layers

2002 ◽  
Vol 472 ◽  
pp. 229-261 ◽  
Author(s):  
LUCA BRANDT ◽  
DAN S. HENNINGSON
Keyword(s):  
Boundary Layer ◽  
Pressure Gradient ◽  
High Speed ◽  
Plate Boundary ◽  
Transition Process ◽  
Free Stream Turbulence ◽  
Tollmien Schlichting ◽  
Streamwise Streaks ◽  
The Stability ◽  
Optimal Disturbances

A transition scenario initiated by streamwise low- and high-speed streaks in a flat-plate boundary layer is studied. In many shear flows, the perturbations that show the highest potential for transient energy amplification consist of streamwise-aligned vortices. Due to the lift-up mechanism these optimal disturbances lead to elongated streamwise streaks downstream, with significant spanwise modulation. In a previous investigation (Andersson et al. 2001), the stability of these streaks in a zero-pressure-gradient boundary layer was studied by means of Floquet theory and numerical simulations. The sinuous instability mode was found to be the most dangerous disturbance. We present here the first simulation of the breakdown to turbulence originating from the sinuous instability of streamwise streaks. The main structures observed during the transition process consist of elongated quasi-streamwise vortices located on the flanks of the low-speed streak. Vortices of alternating sign are overlapping in the streamwise direction in a staggered pattern. The present scenario is compared with transition initiated by Tollmien–Schlichting waves and their secondary instability and by-pass transition initiated by a pair of oblique waves. The relevance of this scenario to transition induced by free-stream turbulence is also discussed.

Dynamic Stability of a Motorized High Speed Machine Tool Spindle Supported on Bearings

2014 ◽  
Vol 612 ◽  
pp. 29-34
Author(s):  
Jakeer Hussain Shaik ◽  
J. Srinivas
Keyword(s):  
Machine Tool ◽  
Frequency Response ◽  
High Speed ◽  
Stability Boundary ◽  
Second Phase ◽  
Element Formulation ◽  
Machining Parameters ◽  
Response Functions ◽  
Frequency Response Functions ◽  
The Stability

Dynamic behaviour of spindle system influences chatter stability of machine tool considerably. Self-excited vibrations of the tool results in unstable cutting process which leads to the chatter on the work surface and it reduces the productivity. In this paper, a system of coupled spindle bearing system is employed by considering the angular contact ball bearing forces on stability of machining. Using Timoshenko beam element formulation, the spindle unit is analyzed by including the gyroscopic and centrifugal terms. Frequency response functions at the tool-tip are obtained from the dynamic spindle model. In the second phase, solid model of the system is developed and its dynamic response is obtained from three dimensional finite element analysis. The works on analysis of the stability of milling processes focus on calculating the stability boundary of the machining parameters based on the dynamic models characterizing the milling processes. The stability lobe diagrams are generated from frequency response functions (FRF’s) lead to an stability limit prediction for the system at high speed ranges.

Investigation of the second-mode instability at Mach 14 using calibrated schlieren

2018 ◽  
Vol 845 ◽  
Author(s):  
Richard E. Kennedy ◽  
Stuart J. Laurence ◽  
Michael S. Smith ◽  
Eric C. Marineau
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
High Speed ◽  
Time Resolved ◽  
Unit Reynolds Number ◽  
Harmonic Frequencies ◽  
Nonlinear Phase ◽  
Second Mode ◽  
Set Up ◽  
Good Agreement

Second-mode wave growth within the hypersonic boundary layer of a slender cone is investigated experimentally using high-speed schlieren visualizations. Experiments were performed in AEDC Tunnel 9 over a range of unit Reynolds number conditions at a Mach number of approximately 14. A thin lens with a known density profile placed within the field of view enables calibration of the schlieren set-up, and the relatively high camera frame rates employed allow for the reconstruction of time-resolved pixel intensities at discrete streamwise locations. The calibration in conjunction with the reconstructed signals enables integrated spatial amplification rates ($N$ factors) to be calculated for each unit Reynolds number condition and compared to $N$ factors computed from both pressure transducer measurements and linear parabolized stability equation (PSE) solutions. Good agreement is observed between $N$ factors computed from the schlieren measurements and those computed from the PSE solutions for the most-amplified second-mode frequencies. The streamwise development of $N$ factors calculated from the schlieren measurements compares favourably to that calculated from the pressure measurements with slight variations in the $N$ factor magnitudes calculated for harmonic frequencies. Finally, a bispectral analysis is carried out to identify nonlinear phase-coupled quadratic interactions present within the boundary layer. Multiple interactions are identified and revealed to be associated with the growth of disturbances at higher harmonic frequencies.

Research on Structure and Kinematics of Hexapod Robot Based on the Pneumatic Flexible Joint

2013 ◽  
Vol 401-403 ◽  
pp. 267-271
Author(s):  
De Xu Geng ◽  
He Peng ◽  
Jin Tao Zhang ◽  
Yun Wei Zhao ◽  
Guang Bin Wu
Keyword(s):  
High Speed ◽  
Test Bench ◽  
Control Method ◽  
Hexapod Robot ◽  
Gravity Center ◽  
Pneumatic Control ◽  
Translational Displacement ◽  
New Type ◽  
Set Up ◽  
The Stability

This paper developed a new type of hexapod robot using self-developed flexible space bending joints which can not only move from side to side or back and forth but also rotate. Then the principle of the movement and the gait of the hexapod robot were investigated, the kinematics model on translational displacement and velocity was followed. Furthermore, the test bench and pneumatic control system were set up, and the displacement, velocity and acceleration of the center of were acquired by high-speed camera shooting means. Finally, the stability of the gravity center and the control method of the hexapod robot were studied. The research of this paper provides a theoretical and practical basis for the application of bionic hexapod robot.

Research of Gyroscopic Effects on the Stability of High Speed Milling

2010 ◽  
Vol 431-432 ◽  
pp. 369-372 ◽  
Author(s):  
Xi Qing Xu ◽  
Wei Xiao Tang ◽  
Shan Shan Sun
Keyword(s):  
High Speed ◽  
Stability Limit ◽  
High Speed Milling ◽  
High Productivity ◽  
Rotating Speed ◽  
Manufacture Industry ◽  
Set Up ◽  
The Stability ◽  
Gyroscopic Effects ◽  
Time Invariant

High-speed milling (HSM) which is characterized as high productivity and low power consumption can be widely used in the manufacture industry. However, while the speed of spindle-tool reach the high speed range, the prediction of its stable milling faces more difficulties, as the gyroscopic effects become prominent. In this paper, a dynamics model of HSM system was set up considering the influence of gyroscopic moment due to high rotating speed of spindle-tool. Then a method was proposed by transforming time-varying stiffness system into fixed-step time invariant one. Finally the stability lobes diagrams (SLD) was elaborated. The results shows that the gyroscopic effects due to high rotating speed have non-negligible impact on the stability limitation, which must be considered for the predicting of stability limit in the high speed milling.

LANDSLIDE RISK MANAGEMENT IN THE COASTAL ZONE OF THE KUIBYSHEV RESERVOIR DUE THE DESIGN OF HIGH-SPEED LINE "MOSCOW-KAZAN"

2017 ◽  
Author(s):  
Nikolai Petrov ◽  
Nikolai Petrov ◽  
Inna Nikonorova ◽  
Inna Nikonorova ◽  
Vladimir Mashin ◽  
...  
Keyword(s):  
High Speed ◽  
Computational Models ◽  
Stable State ◽  
Landslide Risk ◽  
Kuibyshev Reservoir ◽  
Stepped Surface ◽  
The Stability ◽  
Landslide Slope ◽  
The Village

High-speed railway "Moscow-Kazan" by the draft crosses the Volga (Kuibyshev reservoir) in Chuvashia region 500 m below the village of New Kushnikovo. The crossing plot is a right-bank landslide slope with a stepped surface. Its height is 80 m; the slope steepness -15-16o. The authors should assess the risk of landslides and recommend anti-landslide measures to ensure the safety of the future bridge. For this landslide factors have been analyzed, slope stability assessment has been performed and recommendations have been suggested. The role of the following factors have been analyzed: 1) hydrologic - erosion and abrasion reservoir and runoff role; 2) lithologyc (the presence of Urzhum and Northern Dvina horizons of plastically deformable rocks, displacement areas); 3) hydrogeological (the role of perched, ground and interstratal water); 4) geomorphological (presence of the elemental composition of sliding systems and their structure in the relief); 5) exogeodynamic (cycles and stages of landslide systems development, mechanisms and relationship between landslide tiers of different generations and blocks contained in tiers). As a result 6-7 computational models at each of the three engineering-geological sections were made. The stability was evaluated by the method “of the leaning slope”. It is proved that the slope is in a very stable state and requires the following measures: 1) unloading (truncation) of active heads blocks of landslide tiers) and the edge of the plateau, 2) regulation of the surface and groundwater flow, 3) concrete dam, if necessary.

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