Dynamic Performance Characteristics of Floating-Ring Bearings With Varied Oil-Injection Swirl-Control Angles

2014 ◽  
Vol 137 (2) ◽  
Author(s):  
Daniel Tamunodukobipi ◽  
Chang Ho Kim ◽  
Yong-Bok Lee
Keyword(s):  
Test Data ◽  
Hydrodynamic Instability ◽  
Load Capacity ◽  
Dynamic Performance ◽  
Efficient Solutions ◽  
Test Results ◽  
Clearance Ratio ◽  
Thermal Growth ◽  
Oil Injection ◽  
Sufficient Test

Hydrodynamic instability is a prime causative of performance irregularities and violent vibrations in floating-ring bearing (FRB) supported turbosystems. The quest for energy-efficient solutions to this has stimulated the development of diverse FRB design-geometries, dimensional relationships, and surface-contours. Unfortunately, these modifications are characterized mainly by model-predictors, which results lack sufficient test-data to benchmark their authenticities. This work presents the concept and the test-data of flow redirection in FRBs by using an oil-injection swirl-control mechanism (OISCM) to attenuate rotordynamic instabilities. FRBs with radius ratio = 1.75 and clearance ratio = 1.5 are tested for various OISCM angles (0 deg, 30 deg, and 60 deg) and under a specific load = 50 kN/m2. The test results indicate that FRBs with OISCM demonstrate substantial improvements in damping and stability characteristics. Their whirl-frequency-ratio (WFR) and cross-coupled forces are lower because of improved symmetry of films' pressure-forces (Kxx ≈ Kyy). Although the magnitudes of direct damping are higher (|Cxx| = 16.92 kN s/m for 60 deg and 6.03 kN s/m for 0 deg), the load capacity (Kxx) is slightly lower than the normal (0 deg), injection. Nonetheless, this discrepancy in load capacities becomes insignificant for speeds above 22 krpm. The WFR and subsynchronous amplitudes, which are graphic reflections of the bearing-based instability, become progressively smaller with increasing OISCM angle. However, this advantage at elevated speeds can only be sustained by a corresponding increase in oil-supply pressure to circumvent the advent of a starved inner-film and its attendant imbalance response and thermal growth. In closure, the OISCM bearing is more effective for mitigating rotordynamic instabilities in turborotors than conventional FRBs.

scholarly journals Field Tests of Deep Power-installed Screw Anchors in Permafrost

1974 ◽  
Vol 11 (3) ◽  
pp. 348-358 ◽  
Author(s):  
G. H. Johnston ◽  
B. Ladanyi
Keyword(s):  
Test Data ◽  
Creep Behavior ◽  
Load Capacity ◽  
Field Tests ◽  
Secondary Creep ◽  
Test Results ◽  
Test Program ◽  
Slip Surfaces

A test program was conducted in northern Manitoba to evaluate the creep behavior and load capacity of 8-, 10-, and 15-in. (20.3-, 25.4-, and 38.1-cm) diameter power-installed screw anchors embedded in permafrost (frozen, stratified silts and clays containing ice at about 31.5 °F (−0.3 °C)). The test results show that the anchors behaved under uplift loads, in a manner that was essentially very similar to that exhibited by deep footings of the same size. No failure planes (slip surfaces) were observed around the plates but a deformed zone above the plates was clearly visible in the varved soil when the anchors were excavated after testing. A method of analysis which allows the test data to be used directly for design, based on secondary creep rates and allowable displacements, is described.

Pemberian Umpan Balik Dalam Meningkatkan Hasil Belajar dan Minat Belajar Mahasiswa

2015 ◽  
Vol 4 (3) ◽  
Author(s):  
Seruni Seruni ◽  
Nurul Hikmah
Keyword(s):  
Information Technology ◽  
Learning Outcomes ◽  
Test Data ◽  
Random Sampling ◽  
Covariance Matrices ◽  
Test Results ◽  
Immediate Feedback ◽  
Statistics Course ◽  
Independent Variable ◽  
Descriptive Statistical Analysis

<p>The purpose of this study is to find and analyze the effect of feedback on <br />learning outcomes in mathematics and an interest in basic statistics course. The <br />population in this study are affordable Information Technology Student cademic Year 2012/2013 Semester II Indraprasta PGRI University of South Jakarta. Sample The study sample was obtained through random sampling. This study used an experimental method to the analysis using the MANOVA test. This study has three variables, consisting of: one independent variable, namely the provision of feedback (immediate and delayed), and two dependent variable is the result of interest in the study of mathematics and basic statistics course. The data was collected for the test results to learn mathematics, and a questionnaire for the interest in basic statistics course. Collected data were analyzed using the MANOVA test. Before the data were analyzed, first performed descriptive statistical analysis and test data analysis requirements (test data normality and homogeneity of covariance matrices). The results show that the learning outcomes of interest in mathematics and basic statistics course for students who are given immediate feedback higher than students given feedback delayed. <br /><br /></p>

Measurements of Rotordynamic Coefficients of Hybrid Bearings With (a) a Plugged Orifice, and (b) a Worn Land Surface

2002 ◽  
Vol 124 (2) ◽  
pp. 363-368 ◽  
Author(s):  
F. Laurant ◽  
D. W. Childs
Keyword(s):  
Test Data ◽  
Land Surface ◽  
Rocket Engine ◽  
Liquid Rocket Engine ◽  
Test Results ◽  
Rotordynamic Coefficients ◽  
Hybrid Bearing ◽  
Liquid Rocket

Test results are presented for the rotordynamic coefficients of a hybrid bearing that is representative of bearings for liquid-rocket-engine turbopump applications. The bearing is tested in the following two degraded conditions: (a) one of five orifices plugged, and (b) a locally enlarged clearance to simulate a worn condition. Test data are presented at 24,600 rpm, with supply pressures of 4.0, 5.5, and 7.0 MPa, and eccentricity ratios from 0.1 to 0.5 in 0.1 increments. Overall, the results suggest that neither a single plugged orifice nor significant wear on the bearing land will “disable” a well-designed hybrid bearing. These results do not speak to multiple plugged orifices and are not an endorsement for operations without filters to prevent plugging orifices.

A Mechatronic Approach to Compact Fluid Disc Valve Design

1995 ◽  
Vol 209 (2) ◽  
pp. 115-125
Author(s):  
G A Parker ◽  
Y B Sun
Keyword(s):  
Low Cost ◽  
Dynamic Performance ◽  
Operating Mode ◽  
Industrial Applications ◽  
Test Results ◽  
Valve Design ◽  
Electromagnetic Characteristics ◽  
High Control ◽  
Fail Safe ◽  
Pilot Valve

The work presented in this paper deals mainly with a mechatronic approach to compact disc valve design and concentrates on improvements to the disc valve electromagnetic characteristics, the diaphragm design and the dynamic performance. A novel diaphragm-disc force motor has been successfully developed incorporating a pair of permanent ring magnets. It has the advantages of low electric power consumption at the null position, dual-lane electrical structure for fail-safe operation, high control accuracy and should be competitive with existing torque motors due to its low cost and simple construction. The research involved designing and testing a prototype disc pilot valve with a dual-lane operating mode. The test results showed that the valve has satisfactory static and dynamic characteristics for industrial applications.

Two important bridges protected from earthquake by extremely big sliding pendulum isolators

2021 ◽  
Author(s):  
Agostino Marioni ◽  
Roberto Dalpedri ◽  
Marco Banfi ◽  
Carla Cai
Keyword(s):  
Load Capacity ◽  
Special Focus ◽  
South East Asia ◽  
Vertical Load ◽  
Test Results ◽  
Surface Type ◽  
Total Length ◽  
Padma River ◽  
The Difference ◽  
Under Construction

<p>The Padma Bridge is a multipurpose road-rail bridge across the Padma River currently under construction in Bangladesh and is one of the most important projects in the whole south east Asia with a total length of 6150 m. The maximum design vertical load reaches 98725 kN.</p><p>The Holtekamp Bridge is a steel road bridge with 2 main spans of 150 m and 2 lateral spans of 75 for a total length of 450 m. The bridge is isolated by use of sliding pendulum isolators having a maximum vertical load capacity at ULS of 54915 kN.</p><p>In both cases the isolators are double sliding surface type but with a different approach about the central articulation. The paper aims to put in evidence the difference in behaviour of the 2 types of pendulum, analysing both the theoretical approach and the test results with a special focus over the adopted solution for perform the test on a device which exceed the capacity of aby existing laboratory.</p>

MENINGKATKAN KETERAMPILAN MENULIS PUISI MELALUI MEDIA TULISAN BERGAMBAR (MEME) DI INSTAGRAM PADA PESERTA DIDIK KELAS VIII G SMPN 24 SURABAYA

Buana Bastra ◽  
2020 ◽  
Vol 7 (2) ◽  
pp. 26-31
Author(s):  
Prily Yulia Utomo Putri ◽  
Tri Indrayanti
Keyword(s):  
Data Analysis ◽  
Data Collection ◽  
Test Data ◽  
Writing Skills ◽  
Test Results ◽  
Population Activity ◽  
Data Analysis Technique ◽  
Analysis Technique ◽  
Class Viii

This research is a research follow class by using the secound cycle that there is the first cycle and cycle II. On the cycle I and cycle II each cycle there four stage of the (1) planning, (2) implementation of action, (3) observations, and (4) reflection. Each cycle has two meetings in one week, namely the first meeting and the second meeting with the allocation 2 x 40 minutes of each meeting. Subject in research is learners class VIII G SMPN 24 Surabaya totaling 37 learners contained 16 learners men and 21 learners woman. This school is located in Jl. Kebraon Indah Permai Blok K/23 A Surabaya. Data collection techniques to use the observation and test, data analysis technique using the percentage of. Based on the results of data analysis, it can be concluded that using pictorial writing media on the meme on Instagram can improve the writing skills of class students VIII G SMPN 24 Surabaya. This can be seen from (1) population activity in the cycle I 84,61% on the cycle II 100%, (2) activity learners in cycle I 83,44% on the cycle II 90,20%, (3) the test results writing skills poerty in cycle I 56,73% one the cycle of II increased 83,70%.

Cavitation Properties of Liquids

1964 ◽  
Vol 86 (2) ◽  
pp. 195-199 ◽  
Author(s):  
A. J. Stepanoff
Keyword(s):  
Thermal Properties ◽  
Molten Metal ◽  
Test Data ◽  
Centrifugal Pumps ◽  
Cavitation Behavior ◽  
Sufficient Test

A method of representing the thermal properties of liquids is offered such that cavitation behavior of centrifugal pumps handling any liquid—molten metal, hydrocarbons, cryogenics—can be accurately evaluated. Sufficient test data are available to illustrate the use of the method. The paper is a supplement to the article published earlier [1] by the author.

Calculation of Cylindrical Worm Gear Drives of Different Tooth Profiles

1981 ◽  
Vol 103 (1) ◽  
pp. 73-82 ◽  
Author(s):  
H. Winter ◽  
H. Wilkesmann
Keyword(s):  
Coefficient Of Friction ◽  
Theoretical Basis ◽  
Power Loss ◽  
Influence Factor ◽  
Load Capacity ◽  
Worm Gear ◽  
Important Influence ◽  
Test Results ◽  
The Coefficient Of Friction ◽  
Gear Drives

The formulae of classical hydrodynamics are not suitable for the calculation of load capacity and power loss of worm gear drives. Thus a theoretical basis had to be developed for the comparison of different tooth profiles, materials of worm and worm wheel and lubricants. The data obtained were compared with test results. It proved that the coefficient of friction is an important influence factor.

Durability of BFRP and Hybrid FRP Sheets under Freeze-Thaw Cycling

2010 ◽  
Vol 163-167 ◽  
pp. 3297-3300 ◽  
Author(s):  
Jia Wei Shi ◽  
Hong Zhu ◽  
Zhi Shen Wu ◽  
Gang Wu
Keyword(s):  
Mechanical Properties ◽  
Test Data ◽  
Mechanical Characteristics ◽  
Test Results ◽  
Freeze Thaw ◽  
Frp Composites ◽  
Test Parameters ◽  
The Stability ◽  
Better Than

Coupon tests were conducted to investigate the mechanical characteristics of basalt FRP (BFRP) sheet, basalt-carbon hybrid FRP sheets and the corresponding epoxy rein under the effect of freeze-thaw cycling. FRP sheets and epoxy rein coupons were subjected to up to 200 and 250 freeze-thaw cycles respectively. Test parameters included the number of freeze-thaw cycles and the types of FRP composites. Test results show that (1) BFRP sheet perform better than CFRP or GFRP sheets under high freeze-thaw cycles; (2) exposed hybrid FRP sheets not only show very little loss in mechanical properties, but also contribute to the stability of test data; (3) mechanical properties of rein epoxy decrease significantly with increasing freeze-thaw cycles.

Leakage, Drag Power and Rotordynamic Force Coefficients of an Air in Oil (Wet) Annular Seal

2017 ◽  
Author(s):  
Luis San Andrés ◽  
Xueliang Lu
Keyword(s):  
Test Data ◽  
Volume Fraction ◽  
Damping Coefficient ◽  
Liquid Volume ◽  
Pure Liquid ◽  
Test Results ◽  
Liquid Volume Fraction ◽  
Force Coefficients ◽  
Damping Coefficients ◽  
Annular Seal

Wet gas compression systems and multiphase pumps are enabling technologies for the deep sea oil and gas industry. This extreme environment determines both machine types have to handle mixtures with a gas in liquid volume fraction (GVF) varying over a wide range (0 to 1). The gas (or liquid) content affects the system pumping (or compression) efficiency and reliability, and places a penalty in leakage and rotordynamic performance in secondary flow components, namely seals. In 2015, tests were conducted with a short length smooth surface annular seal (L/D = 0.36, radial clearance = 0.127 mm) operating with an oil in air mixture whose liquid volume fraction (LVF) varied to 4%. The test results with a stationary journal show the dramatic effect of a few droplets of liquid on the production of large damping coefficients. This paper presents further measurements and predictions of leakage, drag power, and rotordynamic force coefficients conducted with the same test seal and a rotating journal. The seal is supplied with a mixture (air in ISO VG 10 oil), varying from a pure liquid to an inlet GVF = 0.9 (mostly gas), a typical range in multiphase pumps. For operation with a supply pressure (Ps) up to 3.5 bar (a), discharge pressure (Pa) = 1 bar (a), and various shaft speed (Ω) to 3.5 krpm (ΩR = 23.3 m/s), the flow is laminar with either a pure oil or a mixture. As the inlet GVF increases to 0.9 the mass flow rate and drag power decrease monotonically by 25% and 85% when compared to the pure liquid case, respectively. For operation with Ps = 2.5 bar (a) and Ω to 3.5 krpm, dynamic load tests with frequency 0 < ω < 110 Hz are conducted to procure rotordynamic force coefficients. A direct stiffness (K), an added mass (M) and a viscous damping coefficient (C) represent well the seal lubricated with a pure oil. For tests with a mixture (GVFmax = 0.9), the seal dynamic complex stiffness Re(H) increases with whirl frequency (ω); that is, Re(H) differs from (K-ω2M). Both the seal cross coupled stiffnesses (KXY and −KYX) and direct damping coefficients (CXX and CYY) decrease by approximately 75% as the inlet GVF increases to 0.9. The finding reveals that the frequency at which the effective damping coefficient (CXXeff = CXX-KXY/ω) changes from negative to positive (i.e., a crossover frequency) drops from 50% of the rotor speed (ω = 1/2 Ω) for a seal with pure oil to a lesser magnitude for operation with a mixture. Predictions for leakage and drag power based on a homogeneous bulk flow model match well the test data for operation with inlet GVF up to 0.9. Predicted force coefficients correlate well with the test data for mixtures with GVF up to 0.6. For a mixture with a larger GVF, the model under predicts the direct damping coefficients by as much as 40%. The tests also reveal the appearance of a self-excited seal motion with a low frequency; its amplitude and broad band frequency (centered at around ∼12 Hz) persist and increase as the gas content in the mixture increase. The test results show that an accurate quantification of wet seals dynamic force response is necessary for the design of robust subsea flow assurance systems.

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