Steady-State Fluid Mechanics and Pipe System Components

2013 ◽  
pp. 5-118
Keyword(s):  
Steady State ◽  
Fluid Mechanics ◽  
Pipe System ◽  
System Components

Numerical Model of a Tandem Reciprocating Hydraulic Rod Seal

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Bo Yang ◽  
Richard F. Salant
Keyword(s):  
Steady State ◽  
Numerical Model ◽  
Fluid Mechanics ◽  
Contact Mechanics ◽  
Computational Procedure ◽  
Stroke Length ◽  
Lip Seal ◽  
Through Flow ◽  
Deformation Mechanics

A numerical model of a tandem reciprocating hydraulic rod seal, consisting of two elastomeric U cup seals, has been constructed. It is applicable to cases in which the stroke length is significantly larger than the seal width. The model consists of coupled steady state fluid mechanics, deformation mechanics, and contact mechanics analyses, with an iterative computational procedure. The behaviors of the two seals are coupled through the pressure∕density in the interseal region and through flow continuity. Results for a typical tandem seal are compared to those of a single seal and a double lip seal.

Novel models of power system components for implicit solution of the adjusted power flow problem

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sunil S. Damodhar
Keyword(s):  
Steady State ◽  
Power System ◽  
Conventional Method ◽  
Power Flow ◽  
Flow Problem ◽  
Phase Shifting ◽  
Outer Loop ◽  
Facts Devices ◽  
System Components ◽  
Power Flow Problem

Abstract The solution of the adjusted power flow problem involves handling power system components whose control characteristics possess operational limits. Examples include generator reactive power limits, tap-changing and phase-shifting transformers, and FACTS devices. While the conventional method involves checking for limit violations in an outer loop drawn around the unadjusted power flow problem being solved by the Newton-Raphson (NR) method, for iterative processes, it is desirable to have smooth, continuously differentiable models implicitly handled within a single loop. A novel formulation for a subset of devices is presented for implicit handling within power flow. The steady state characteristics of tap-changing and phase-shifting transformers, and FACTS devices SVC and STATCOM, can be described using the “cut function”, a piecewise linear function traditionally employed in neural networks. A new approximation of the cut function is used for formulating novel equations describing the steady state characteristics. An augmented set of equations is formed and solved by the NR method, eliminating the need of an outer loop. The efficacy of the proposed method is demonstrated by employing it for plotting bus voltage profiles and determining maximum loadability of test systems. Comparisons with the conventional method show that significant savings in computation can be achieved.

Steady-State Single-Phase Models of Power System Components

2017 ◽  
pp. 51-94
Author(s):  
Edmund Handschin ◽  
Antonio F. Otero ◽  
José Cidrás
Keyword(s):  
Steady State ◽  
Power System ◽  
Single Phase ◽  
System Components ◽  
Phase Models

Thermal Analysis of Sandwich Pipes With Active Electrical Heating

2003 ◽  
Author(s):  
Jian Su ◽  
Djane R. Cerqueira ◽  
Segen F. Estefen
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Oil And Gas ◽  
Gas Production ◽  
Heat Transfer Analysis ◽  
Electrical Heating ◽  
Flow Assurance ◽  
Insulation Material ◽  
Power Requirement ◽  
Pipe System

Sandwich pipes consisting of two concentric metal pipes with insulation material in annulus have been developed to meet challenging mechanical and thermal requirements of deep and ultra deepwater oil and gas production. Passive thermal insulation is designed to meet flow assurance requirements under steady-state production conditions, but is unlikely to meet more severe conditions during transient events such as warm-up and cool-down. In this work, we propose a new sandwhich pipe system with active electrical heating, provided by a number of electrical resistance strips stuck longitudinally over the outer surface of the inner metal pipe. A steady-state heat transfer analysis is carried out to determine the temperature distribution in a cross section of the sandwich pipe, the power requirement of electrical heating, and the overall heat transfer coefficient. It is shown that the sandwich pipe with active heating is a viable solution to meet server flow assurance requirements of ultra deepwater oil production.

Soft EHL Simulations of U-Cup and Step Hydraulic Rod Seals

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Bo Yang ◽  
Richard F. Salant
Keyword(s):  
Steady State ◽  
Fluid Mechanics ◽  
Contact Mechanics ◽  
Critical Speed ◽  
Thermal Analyses ◽  
Elastohydrodynamic Lubrication ◽  
Computational Procedure ◽  
Stroke Length ◽  
Deformation Mechanics ◽  
Rod Seals

A numerical soft elastohydrodynamic lubrication model of a reciprocating hydraulic seal has been used to simulate the performance of a U-cup seal and a step seal in a conventional actuator. The model consists of coupled steady state fluid mechanics, deformation mechanics, contact mechanics, and thermal analyses, with an iterative computational procedure. The results indicate that for a given seal roughness and stroke length there is a critical rod speed above which the seal will not leak. The critical speed is dependent on both seal roughness and sealed pressure.

scholarly journals Investigation of Steady-State Heat Extraction Rates for Different Borehole Heat Exchanger Configuration from the Aspect of Implementation of New TurboCollectorTM Pipe System Design

2019 ◽  
Author(s):  
Tomislav Kurevija ◽  
Adib Kalantar ◽  
Marija Macenić ◽  
Josipa Hranić
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Heat Exchanger ◽  
Thermal Response ◽  
Heat Extraction ◽  
Double Loop ◽  
Borehole Heat Exchanger ◽  
Pipe System ◽  
State Heat ◽  
Steady State Heat

When considering implementation of shallow geothermal energy as a renewable source for heating and cooling of the building, special care should be taken in hydraulic design of borehole heat exchanger system. Laminar flow can occur in pipes due to usage of glycol mixture at low temperature or inadequate flow rate. This can lead to lower heat extraction and rejection rates of the exchanger because of higher thermal resistances. Furthermore, by increasing flow rate to achieve turbulent flow and satisfactory heat transfer rate can lead to increase the pressure drop of the system and oversizing of circulation pump which leads to impairment of seasonal coefficient of performance at the heat pump. Most frequently used borehole heat exchanger system in Europe is double-loop pipe system with smooth inner wall. Lately, development is focused on implementation of different configuration as well as with ribbed inner wall which ensures turbulent flow in the system, even at lower flow rates. At a location in Zagreb, classical and extended thermal response test was conducted on three different heat exchanger configurations in the same geological environment. With classic TRT test, thermogeological properties of the ground and thermal resistance of the borehole were determined for each smooth or turbulator pipe configuration. Extended Steady-State Thermal Response Step Test (TRST) was implemented, which incorporate series of power steps to determine borehole extraction rate at the define steady-state heat transfer conditions of 0/-3°C. Results show that heat exchangers with ribbed inner pipe wall have advantages over classic double-loop smooth pipe design, in terms of greater steady state heat extraction rate and more favorable hydraulic conditions.

STOCHASTIC ANALYSIS FOR THE DESCRIPTION AND SYNTHESIS OF PREDATOR–PREY SYSTEMS

1977 ◽  
Vol 109 (9) ◽  
pp. 1167-1174 ◽  
Author(s):  
Guy L. Curry ◽  
Don W. DeMichele
Keyword(s):  
Steady State ◽  
Mathematical Analysis ◽  
Queueing Theory ◽  
Stochastic Analysis ◽  
Analysis Approach ◽  
Systems Modeling ◽  
Service Facility ◽  
Predator Prey ◽  
System Components ◽  
Transient And Steady State

AbstractIn this paper, a stochastic analysis approach for predator–prey systems modeling is developed. The states of the system are assumed to have a natural probabilistic variation. Elements of queueing theory are used to describe these variations and to obtain both the transient and steady-state results for the system. The predator is considered analogous to a service facility and the prey as customers to be served. The Holling disk equation and mantid–fly experiments are analyzed by this approach. The method provides a framework for a straightforward synthesis of the system components and is readily generalized for multiple predator systems. Furthermore, hunger and other behavioral aspects can be easily incorporated into the mathematical analysis.

Soft EHL Analysis of a Reciprocating Hydraulic Step Seal

2008 ◽  
Author(s):  
Bo Yang ◽  
Richard F. Salant
Keyword(s):  
Steady State ◽  
Fluid Mechanics ◽  
Contact Mechanics ◽  
Thermal Analyses ◽  
Elastohydrodynamic Lubrication ◽  
Computational Procedure ◽  
Deformation Mechanics

A numerical soft EHL (elastohydrodynamic lubrication) model of a reciprocating hydraulic step seal has been used to analyze seal performance. The model consists of coupled steady state fluid mechanics, deformation mechanics, contact mechanics and thermal analyses, with an iterative computational procedure. Results for a typical step seal are compared with those of a double lip U-cup seal.

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