scholarly journals Wall Pressures In a Channel Flow Obstructed By a Line of Inclined Rods: Invariant Groups and Semi-Empirical Correlations

2021 ◽  
Author(s):  
Víctor Herrero ◽  
Hernán Ferrari ◽  
Raul Marino ◽  
Alejandro Clausse
Keyword(s):  
Inclination Angle ◽  
Rectangular Channel ◽  
Momentum Conservation ◽  
Empirical Correlations ◽  
Independence Principle ◽  
Dimensionless Groups ◽  
Conservation Principles ◽  
Different Diameters ◽  
Semi Empirical ◽  
Velocity Projection

Abstract An experiment is conducted in a rectangular channel obstructed by a transverse line of four inclined cylindrical rods. The wall pressure around the perimeter of a central rod and the pressure drop through the channel are measured varying the inclination angle of the rods. Three assemblies of rods with different diameters are tested. The measurements were analyzed applying momentum conservation principles and semi-empirical considerations. Several invariant dimensionless groups of parameters relating the pressure at key locations of the system with characteristic dimensions of the rods are produced. It was found that the independence principle holds for most of the Euler numbers characterizing the pressure at different locations, that is, the group is independent of the inclination angle provided that the inlet velocity projection normal to the rods is used to non-dimensionalize the pressure. The resulting semi-empirical correlations can be useful for designing similar hydraulic units.

A Critical Review of NOx Correlations for Gas Turbine Combustors

1975 ◽  
Author(s):  
D. A. Sullivan ◽  
P. A. Mas
Keyword(s):  
Experimental Data ◽  
Data Base ◽  
Gas Turbine ◽  
Critical Review ◽  
Inlet Temperature ◽  
Nox Emissions ◽  
Empirical Correlations ◽  
Gas Turbine Combustors ◽  
Semi Empirical ◽  
Adequate Data

The effect of inlet temperature, pressure, air flowrate and fuel-to-air ratio on NOx emissions from gas turbine combustors has received considerable attention in recent years. A number of semi-empirical and empirical correlations relating these variables to NOx emissions have appeared in the literature. They differ both in fundamental assumptions and in their predictions. In the present work, these simple NOx correlations are compared to each other and to experimental data. A review of existing experimental data shows that an adequate data base does not exist to evaluate properly the various NOx correlations. Recommendations are proposed to resolve this problem in the future.

Determination of the Effective Depth for Double-Fiber Fluorometric Sensors

1992 ◽  
Vol 46 (6) ◽  
pp. 919-924 ◽  
Author(s):  
Zhong Yuan Zhu ◽  
M. Cecilia Yappert
Keyword(s):  
Fiber Optic Sensor ◽  
Fluorescence Signal ◽  
Acceptance Angle ◽  
Fiber Sensors ◽  
Sample Depth ◽  
Effective Depth ◽  
Different Diameters ◽  
Semi Empirical ◽  
Analytical Expressions

The relationship between the relative fluorescence signal excited and collected with a double-fiber optic sensor and the sample depth has been investigated. The complexity of the analytical expressions for the relative fluorescence signal and the effective depth was reduced by deriving a set of semi-empirical equations which can be evaluated in a simple fashion. These expressions take into account the configuration of the sensor, i.e., fiber diameter, acceptance angle, and separation between fibers. The expressions were tested with the use of double-fiber sensors with different diameters and separations between fibers. The reduction of the effective depth in solutions with significant absorbance was evaluated.

Predicting pressure piling by semi-empirical correlations

2005 ◽  
Vol 40 (3) ◽  
pp. 282-298 ◽  
Author(s):  
A. Di Benedetto ◽  
E. Salzano ◽  
G. Russo
Keyword(s):  
Empirical Correlations ◽  
Semi Empirical

scholarly journals VERIFICAÇÃO DO DESEMPENHO DAS ESTACAS INJETADAS AUTOPERFURANTES EXECUTADAS EM SOLOS ARENOSOS PARA CONSTRUÇÃO DE USINA EÓLICA

2017 ◽  
Vol 13 (2) ◽  
Author(s):  
Rodrigo Cerqueira Rogerio
Keyword(s):  
Structural Characteristics ◽  
Load Capacity ◽  
The Self ◽  
Executive Processes ◽  
Empirical Methods ◽  
Deep Drilling ◽  
Load Tests ◽  
Different Diameters ◽  
Semi Empirical

RESUMO: Apresenta-se neste trabalho a solução adotada para execução das fundações do Parque de Usina Eólica localizado no Ceará, com a utilização das estacas injetadas autoperfurantes, executadas em presença de solos arenosos. No qual consiste em perfurar o solo com altíssima velocidade por rotação e “pull down”, através da injeção simultânea de nata de cimento com medias pressões. Ocasionando na estaca um diâmetro final que pode obter o dobro do bit de perfuração, de acordo com o tipo de solo, gerado pelo efeito do jato da nata de cimento. Detalhando os processos executivos, verificando os aspectos técnicos e operacionais, para melhor compreender as características estruturais deste elemento. De forma a verificar “in situ” o desempenho deste novo tipo de fundação profunda, foram realizadas provas de carga, em estacas com diferentes diâmetros e comprimentos, realizadas em perfis estratigráficos de solos arenosos, para melhor avaliação de sua capacidade de carga. Analisando-se os ensaios das provas de carga interpretados a base da extrapolação da curva carga versus recalque e das previsões da capacidade de carga, obtidas por meio dos métodos semi-empíricos de correlação com ensaios de penetração (SPT), avaliando os padrões de execução desta tipologia de estaca injetada para comunidade geotécnica. ABSTRACT: This paper aims to establish the selected solution to except the foundations of the Wind Energy Park in Ceará (Brazil), with an executive methodology of the self-drilling injection piles framed in loco in Sandy soil. In which the soil drilling is done with the highest speed by rotation and pull down, through the simultaneous injection of grouting with medium pressures. This kind of drilling causes in the pile a final diameter that can get the double bore bit, according to the type of soil, done by the grouting blast. The executive processes are detailed as a whole, and also presenting the pile materials composition, in order to understand the structural characteristics of this element. To verify the performance of this new kind of deep drilling, instrumentations were done: settlement control and load tests in constructions with different structural characteristics, in self-drilling injected piles with different diameters and length, done in stratigraphical sandy, for a better evaluation of its load capacity. Analyzing the essays of load tests interpreted in the basis of curve extrapolation load versus settlement and the previsions of the load capacity, obtained by semi-empirical methods correlating with the penetrations methods (SPT), offering information to the geotechnical community.

scholarly journals A STUDY INTO ICE BUILD-UP AND MELTING ON VERTICAL COOLED PIPES

2016 ◽  
Vol 52 (3) ◽  
Author(s):  
Y. Zasiadko ◽  
O. Pylypenko ◽  
A. Forsiuk ◽  
R. Gryshchenko
Keyword(s):  
Thermal Energy ◽  
Experimental Unit ◽  
Ice Thickness ◽  
Ice Melting ◽  
Empirical Correlations ◽  
Time Intervals ◽  
Ice Accumulation ◽  
Time Periods ◽  
Semi Empirical

The use of cold accumulators based on the principle of ice build up on the cooled surfaces during off-peak periods and ice melting during on-peak periods is an effective method of electricity bills reduction. Within comparatively short periods of on-peak demand a noticeable amount of thermal energy related to ice melting is to be released, it becomes clear that not only sizing of ice accumulators based on balance calculations is actual, but also the determination of time periods of ice accumulation becomes critical. This work presents experimental unit for obtaining data on the ice build-up on the vertical cooled pipes and later on to continuously register data on the ice thickness diminishing at the regimes of ice melting when cooling of pipe stops. The data for ice build-up and melting for some regimes have been presented and analyzed. The data form the base for deriving semi-empirical correlations allowing to determine a time intervals necessary to generate of ice layers of a given thickness.

scholarly journals Soil classification at Muaro Baru beach of Padang City using CPT data

2021 ◽  
Vol 331 ◽  
pp. 03005
Author(s):  
Rina Yuliet ◽  
Mas Mera ◽  
Krismon Hidayat
Keyword(s):  
Soil Classification ◽  
Soil Profiles ◽  
Sieve Analysis ◽  
Penetration Test ◽  
Empirical Correlations ◽  
Cone Penetration ◽  
Geotechnical Parameters ◽  
Semi Empirical ◽  
Soil Behaviour ◽  
Behaviour Type

Many semi-empiric correlations have been developed to estimate geotechnical parameters based on Cone Penetration Test (CPT) data for various types of soils. This paper aims to classify soil types based on CPT data with several semi-empiric correlations and compare the results of some of these correlations. In this study, the field CPT and the laboratory test were carried out on soil from two closely spaced locations in the estuary area of Muaro Baru, Padang city. The CPT data was used to determine the soil type using several semi-empirical correlations, namely; friction ratios, Schertmann (1978), Robertson and Campanella (1983), and Robertson et al. (1986), then updated by Robertson in 2010. Soil Behaviour Type (SBT) is based on the cone resistance (qc), sleeve friction (qs), and friction ratio (Rf). The Unified Soil Classification System (USCS) is also used to classify soils using sieve analysis. The results showed that from the several semi-empirical correlations obtained compatibility soil classification and soil profiles.

Convective Heat Transfer at Minimum Fluidization Velocity for Gas-Solid Fluidized Beds

1999 ◽  
Author(s):  
Kal R. Sharma
Keyword(s):  
Heat Transfer ◽  
Fluidized Beds ◽  
Empirical Correlations ◽  
Transfer Coefficients ◽  
Minimum Fluidization Velocity ◽  
Heat Transfer Coefficients ◽  
Fluidization Velocity ◽  
Minimum Fluidization ◽  
Semi Empirical ◽  
The Heat Transfer Coefficient

Abstract Experimentally measured values for the minimum fluidization velocities and time averaged local surface heat transfer coefficients are provided for 16 different cases of fluidizing conditions for gas-solid dense fluidized beds. Semi-empirical Correlations for the minimum fluidization velocity and the heat transfer coefficient at minimum fluidization velocities are provided. The implications of the Peclet number dependence in terms of diffusion and convection is discussed.

scholarly journals Development of small-scale unmanned hydrofoil boats

2020 ◽  
pp. 1-12
Author(s):  
Noah T. Thompson ◽  
Phillip R. Whitworth ◽  
Konstantin I. Matveev
Keyword(s):  
Small Scale ◽  
Empirical Correlations ◽  
Unmanned Surface Vehicles ◽  
High Speeds ◽  
Carbon Fiber Cloth ◽  
Measuring Module ◽  
Design Calculations ◽  
Semi Empirical ◽  
Maritime Community

Unmanned boats have gained a lot of interest in the maritime community during the last decade. Most hydrodynamic platforms employed for unmanned boats are based on traditional relatively simple hulls. In the present study, small-scale hydrofoil-assisted unmanned boats (0.6–0.7 m in length and 3.5–5.5 kg in mass) have been developed and tested. Design calculations using a hydrodynamic transverse-strip engineering method with semi-empirical correlations were applied to determine suitable dimensions for hydrofoil systems. The boat hulls and hydrofoils were fabricated by laying up carbon-fiber cloth sheets on foam cores or 3-D printed profiles. The boats were instrumented with outboard propulsors and electronic equipment for operations in both remote control and autopilot modes. In addition, an in-situ thrust-measuring module was designed and installed at the hull sterns to gather thrust data at GPS-measured speeds in the range between 0 and 11 m/s. The developed boats proved to be robust platforms capable of going over 600 m distances at high speeds while autonomously following preset paths. The presented methods and results can assist engineers developing unmanned surface vehicles that utilize advanced hydrodynamic concepts.

Experimental Thermal Behavior of Electronic Chips in a Channel During Pump-On Transient Period

Volume 4 ◽  
2004 ◽  
Author(s):  
H. Bhowmik ◽  
K. W. Tou ◽  
C. P. Tso
Keyword(s):  
Rectangular Channel ◽  
Heat Fluxes ◽  
Working Fluid ◽  
Heat Sources ◽  
Empirical Correlations ◽  
Heat Transfer Characteristics ◽  
Flux Flow ◽  
Flow Rates ◽  
Discrete Heat Sources ◽  
Transient Period

Experiments are performed to study the heat transfer characteristics during the pump-on transient period from an array of 4 × 1 flush mounted discrete heat sources in a vertical rectangular channel using water as the working fluid. The experimental data covers the flow regime with Reynolds number based on heat source length ranging from 1050 to 2625. The applied uniform heat fluxes to the chips are 1, 3, 5 and 7 W/cm2. The effects of heat flux, flow rates and chip numbers are investigated and empirical correlations are developed for investigated and empirical correlations are developed for individual chips as well as for overall data in the transient regime. The transient correlation recommended is Nul/(Pel)1/3 = 3.5(Fo)1/4.

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