A Review of Slip Factors for Centrifugal Impellers

1967 ◽  
Vol 89 (4) ◽  
pp. 558-566 ◽  
Author(s):  
F. J. Wiesner
Keyword(s):  
Test Data ◽  
Correction Factor ◽  
Classical Method ◽  
Radius Ratio ◽  
Empirical Expression ◽  
General Review ◽  
Empirical Correction ◽  
Slip Factor ◽  
Empirical Correction Factor

This paper contains a general review of the various methods which have been proposed for the estimation of basic slip factors for centrifugal impellers. As a result of this study, it is concluded that the classical method proposed by Busemann in 1929 is still the most generally applicable prediction for the basic slip factor of centrifugal impellers. The paper then presents a very simple empirical expression, which fits the Busemann results extremely well over the whole range of practical blade angles and number of blades up to a limiting inlet-to-outlet radius ratio for the impeller. An empirical correction factor is also proposed for conditions which exceed this limiting radius ratio. Tabular comparisons of slip factors, with test data (where available), are given for over 60 pump and compressor impellers which have been cited previously in the literature, and the author has added data for several more compressor stages from his own experience.

RE-EVALUATION OF THE CORRECTION FACTOR FOR ETHANOL IN THE CALCULATION OF THE OSMOLAL GAP

2009 ◽  
Vol 32 (6S) ◽  
pp. 5
Author(s):  
V Fung ◽  
M Pudek ◽  
F Rosenberg ◽  
D Holmes
Keyword(s):  
Correction Factor ◽  
Freezing Point ◽  
Laboratory Data ◽  
Plasma Osmolality ◽  
High Volume ◽  
Plasma Sodium ◽  
Correction Factors ◽  
Empirical Correction ◽  
Empirical Correction Factor ◽  
Osmolal Gap

Background/objectives: It is well-known that ethanol (EtOH) demonstrates non-ideal solute behaviour in plasma. This is reflected by its larger than expected contribution to the plasma osmolality. Published multiplicative correction factors for the EtOH contribution range from 1.20 to 1.25. The objective of this study is to determine an optimal correction factor specific to the instrumentation at Vancouver General (VGH) and St. Paul's (SPH) Hospitals. Methods: Laboratory data from patients presenting to the two respective emergency department between August 01, 2007 and November 30, 2008 were extracted from the Sunset database. Plasma sodium, urea, glucose, and EtOH were measured using the two high-volume chemistry analyzers employed at the sites: the Siemens (previously Dade) RXL (VGH) and the Siemens (previously Bayer) Advia 1650 (SPH). Plasma osmolality was measured by freezing-point depression and calculated (excluding the EtOH contribution) using the following standard formula (in SI units): 2 [Na] + [Urea] + [Glucose]. Patients without EtOH data or who had undetectable EtOH were excluded as were patients with methanol or ethylene glycol present. Standard regression statistics were employed. Results: Twelve hundred and fifty-three patient samples (n=823 from SPH and n=430 from VGH) were included. Empirical correction factor m, satisfying, Osmol gap (mmol/kg) =m[EtOH] (mmol/L) was consistently found to be 1.15 for VGH, SPH and both combined. Conclusions: The correction factor of 1.15 for ethanol from the current study appears to be more representative and reliable. Further studies to evaluate its validity in other hospital sites as well as its utility in screening patients with known toxic alcohol ingestion will be warranted.

Experimentelle Untersuchungen zur Stark-Verbreiterung der Balmer-Linien Hα und Hβ / Experimental Investigation of the Stark Broadening of the Balmer Lines Hα and Hβ

1973 ◽  
Vol 28 (11) ◽  
pp. 1794-1800 ◽  
Author(s):  
Horst Ehrich ◽  
Hans Jürgen Kusch
Keyword(s):  
Electron Density ◽  
Plasma Temperature ◽  
Light Sources ◽  
Stark Broadening ◽  
Pulsed Discharge ◽  
Empirical Correction ◽  
Wide Range ◽  
Balmer Lines ◽  
Empirical Correction Factor ◽  
Density Scale

The profiles of the Stark broadened Balmer lines Hα and Hβ have been measured in a wide range of temperature and electron density. By the use of different light sources (3 wallstabilized arcs of different design, a pulsed discharge tube and a plexiglass-capillary discharge) the range was ex- tended to 1.0·104≦T≦3.2·104 °K for the plasma temperature and to 1·1016≦ne≦55·1016 cm−3 for the electron density in the Hβ-scale. The experimental profiles of the Hα-line agree with generalized impact approximations if the condition: ne2/3/T>2·107 cm−2 grad−1 is fulfilled. Disagreements between the Hα and Hβ electron density scale can be removed applying an empirical correction-factor to the electron density obtained from the half-width of Hα.

Comparison of Soil Properties From World-Wide Full-Scale Pipe Testing Facilities

2008 ◽  
Author(s):  
D. Rudland ◽  
G. Mannucci ◽  
R. Andrews ◽  
S. Kawaguchi
Keyword(s):  
The United States ◽  
Full Scale ◽  
Pipe Material ◽  
Soil Behavior ◽  
Line Pipe ◽  
Crack Driving Force ◽  
Empirical Correction ◽  
Standard Procedures ◽  
Future Fracture ◽  
Empirical Correction Factor

The dynamic behavior of an axially propagating crack in buried line pipe is dependent not only on the pipe material, and the decompressing gas, but also the surrounding soil. The density and cohesiveness of the soil restrains the forming pipe flaps behind the crack tip and decreases the apparent crack driving force. Traditional fracture analyses, such as the Battelle Two-Curve (BTC) approach, lump the soil behavior into one empirical correction factor that does not differentiate between different soil types. In this effort, soils from the full-scale pipe test facilities in the United States, Italy, United Kingdom, and Denmark, were tested with standard procedures to characterize the soils by type, grain size, density and strength. A comparison of these properties is presented in this archival paper, which can be used in future fracture analysis development efforts.

scholarly journals Weibull and Bootstrap-Based Data-Analytics Framework for Fatigue Life Prognosis of the Pressurized Water Nuclear Reactor Component Under Harsh Reactor Coolant Environment

2019 ◽  
Vol 3 (1) ◽  
Author(s):  
Jae Phil Park ◽  
Subhasish Mohanty ◽  
Chi Bum Bahn ◽  
Saurin Majumdar ◽  
Krishnamurti Natesan
Keyword(s):  
Fatigue Life ◽  
Fatigue Test ◽  
Safety Factor ◽  
Test Data ◽  
Correction Factor ◽  
Data Analytics ◽  
Probabilistic Approach ◽  
Fatigue Curve ◽  
Pressurized Water ◽  
Best Fit

Abstract In general, the fatigue life of a safety critical pressure component is estimated using best-fit fatigue life curves (S-N curves). These curves are estimated based on underlying in-air condition fatigue test data. The best-fitting approach requires a large safety factor to accommodate the uncertainty associated with large scatter in fatigue test data. In addition to this safety factor, reactor component fatigue life prognostics requires an additional correction factor that in general is also estimated deterministically. This additional factor known as the environmental correction factor Fen is to cater the effect of the harsh coolant environment that severely reduces the life of these components. The deterministic Fen factor may also lead to further conservative estimation of fatigue life leading to unnecessary early retirement of costly reactor components. To address the above-mentioned issues, we propose a data-analytics framework which uses Weibull and Bootstrap probabilistic modeling techniques for explicitly quantifying the uncertainty/scatter associated with fatigue life rather than estimating the lives based on a best-fit based deterministic approach. We assume the proposed probabilistic approach would provide the first hand information for assessing the maximum and minimum effects of pressurized water reactor water on the reactor component. In the discussed approach, in addition to the probabilistic fatigue curves, we suggest using a probabilistic environment correction factor Fen. We assume the probabilistic fatigue curve and Fen would capture the S-N data scatter associated with the bulk effect of material grades, surface finish, strain rate, etc. on the material/component fatigue life.

scholarly journals Calibration of 14C Histograms: A Comparison of Methods

Radiocarbon ◽  
1994 ◽  
Vol 36 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Ad Stolk ◽  
Torbjörn E. Törnqvist ◽  
Kilian P. V. Hekhuis ◽  
Henk J. A. Berendsen ◽  
Johannes van der Plicht
Keyword(s):  
Test Data ◽  
Correction Factor ◽  
Time Scale ◽  
Data Sets ◽  
Comparison Of Methods ◽  
Time Intervals ◽  
Individual Calibration ◽  
Basic Approaches ◽  
The Individual ◽  
Calibration Program

The interpretation of 14C histograms is complicated by the non-linearity of the 14C time scale in terms of calendar years, which may result in clustering of 14C ages in certain time intervals unrelated to the (geologic or archaeologic) phenomenon of interest. One can calibrate 14C histograms for such distortions using two basic approaches. The KORHIS method constructs a 14C histogram before calibration is performed by means of a correction factor. We present the CALHIS method based on the Groningen calibration program for individual 14C ages. CALHIS first calibrates single 14C ages and then sums the resulting calibration distributions, thus yielding a calibrated 14C histogram. The individual calibration distributions are normalized to a standard Gaussian distribution before superposition, thus allowing direct comparison among various 14C histograms. Several experiments with test data sets demonstrate that CALHIS produces significantly better results than KORHIS. Although some problems remain (part of the distortions due to 14C variations cannot be eliminated), we show that CALHIS offers good prospects for using 14C histograms, particularly with highly precise and accurate 14C ages.

A Unified Correlation for Slip Factor in Centrifugal Impellers

2005 ◽  
Vol 128 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Theodor W. von Backström
Keyword(s):  
Critical Radius ◽  
Fluid Dynamic ◽  
Prediction Method ◽  
Outer Radius ◽  
Radius Ratio ◽  
Centrifugal Impeller ◽  
Slip Factor ◽  
Curve Fit ◽  
Prime Variable ◽  
Rotor Axis

A method that unifies the trusted centrifugal impeller slip factor prediction methods of Busemann, Stodola, Stanitz, Wiesner, Eck, and Csanady in one equation is presented. The simple analytical method derives the slip velocity in terms of a single relative eddy (SRE) centered on the rotor axis instead of the usual multiple (one per blade passage) eddies. It proposes blade solidity (blade length divided by spacing at rotor exit) as the prime variable determining slip. Comparisons with the analytical solution of Busemann and with tried and trusted methods and measured data show that the SRE method is a feasible replacement for the well-known Wiesner prediction method: it is not a mere curve fit, but is based on a fluid dynamic model; it is inherently sensitive to impeller inner-to-outer radius ratio and does not need a separate calculation to find a critical radius ratio; and it contains a constant, F0, that may be adjusted for specifically constructed families of impellers to improve the accuracy of the prediction. Since many of the other factors that contribute to slip are also dependent on solidity, it is recommended that radial turbomachinery investigators and designers investigate the use of solidity to correlate slip factor.

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