Multiobjective Hydraulic Cylinder Design

1988 ◽  
Vol 110 (1) ◽  
pp. 81-87 ◽  
Author(s):  
Nestor F. Michelena ◽  
Alice M. Agogino
Keyword(s):  
Stress Ratio ◽  
Pressure Ratio ◽  
Circumferential Stress ◽  
Three Dimensional ◽  
Design Procedure ◽  
Hydraulic Cylinder ◽  
Cross Sectional ◽  
Analysis And Design ◽  
Conflicting Objectives ◽  
Monotonicity Analysis

Monotonicity analysis is used to solve a three-objective optimization problem in which a hydraulic cylinder is to be designed. With the additional application of the Karush-Kuhn-Tucker optimality conditions a reduced symbolic design chart is obtained which is then utilized to obtain parametric numerical results. Two- and three-dimensional parametric Pareto-optimal plots are obtained for the three conflicting objectives: (1) cross-sectional area, (2) circumferential stress ratio and (3) pressure ratio. The analysis and design procedure strengthens and extends the results suggested by previous works.

Fanno Design of Blow-Off Lines in Heavy Duty Gas Turbine

2013 ◽  
Author(s):  
Marco Cioffi ◽  
Enrico Puppo ◽  
Andrea Silingardi
Keyword(s):  
Gas Turbines ◽  
Gas Flow ◽  
Initial Conditions ◽  
Three Dimensional ◽  
Design Procedure ◽  
Flow Equation ◽  
Heavy Duty ◽  
Cross Sectional ◽  
Pipe Length ◽  
Choked Flow

In typical heavy duty gas turbines the multistage axial compressor is provided with anti-surge pipelines equipped with on-off valves (blow-off lines), to avoid dangerous flow instabilities during start-ups and shut-downs. Blow-off lines show some very peculiar phenomena and somewhat challenging fluid dynamics, which require a deeper regard. In this paper the blow-off lines in axial gas turbines are analyzed by adopting an adiabatic quasi-unidimensional model of the gas flow through a pipe with a constant cross-sectional area and involving geometrical singularities (Fanno flow). The determination of the Fanno limit, on the basis of the flow equation and the second principle of thermodynamics, shows the existence of a critical pipe length which is a function of the pipe parameters and the initial conditions: for a length greater than this maximum one, the model requires a mass-flow reduction. In addition, in the presence of a regulating valve, so-called multi-choked flow can arise. The semi-analytical model has been implemented and the results have been compared with a three-dimensional CFD analysis and cross-checked with available field data, showing a good agreement. The Fanno model has been applied for the analysis of some of the actual machines in the Ansaldo Energia fleet under different working conditions. The Fanno tool will be part of the design procedure of new machines. In addition it will define related experimental activities.

1995 ASME Gas Turbine Award Paper: Development and Application of a Multistage Navier–Stokes Solver: Part I—Multistage Modeling Using Bodyforces and Deterministic Stresses

1998 ◽  
Vol 120 (2) ◽  
pp. 205-214 ◽  
Author(s):  
C. M. Rhie ◽  
A. J. Gleixner ◽  
D. A. Spear ◽  
C. J. Fischberg ◽  
R. M. Zacharias
Keyword(s):  
Stokes Equations ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Design Procedure ◽  
Potential Interaction ◽  
Theoretical Development ◽  
Navier Stokes ◽  
Radial Profiles ◽  
Compressor Performance ◽  
High Level

A multistage compressor performance analysis method based on the three-dimensional Reynolds-averaged Navier-Stokes equations is presented in this paper. This method is an average passage approach where deterministic stresses are used to ensure continuous physical properties across interface planes. The average unsteady effects due to neighboring blades and/or vanes are approximated using deterministic stresses along with the application of bodyforces. Bodyforces are used to account for the “potential” interaction between closely coupled (staged) rows. Deterministic stresses account for the “average” wake blockage and mixing effects both axially and radially. The attempt here is to implement an approximate technique for incorporating periodic unsteady flow physics that provides for a robust multistage design procedure incorporating reasonable computational efficiency. The present paper gives the theoretical development of the stress/bodyforce models incorporated in the code, and demonstrates the usefulness of these models in practical compressor applications. Compressor performance prediction capability is then established through a rigorous code/model validation effort using the power of networked workstations. The numerical results are compared with experimental data in terms of one-dimensional performance parameters such as total pressure ratio and circumferentially averaged radial profiles deemed critical to compressor design. This methodology allows the designer to design from hub to tip with a high level of confidence in the procedure.

Development and Application of a Multistage Navier-Stokes Solver: Part I — Multistage Modeling Using Bodyforces and Deterministic Stresses

1995 ◽  
Author(s):  
Chae M. Rhie ◽  
Aaron J. Gleixner ◽  
David A. Spear ◽  
Craig J. Fischberg ◽  
Robert M. Zacharias
Keyword(s):  
Stokes Equations ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Design Procedure ◽  
Potential Interaction ◽  
Theoretical Development ◽  
Navier Stokes ◽  
Interface Plane ◽  
Radial Profiles ◽  
Compressor Performance

A novel multistage compressor performance analysis method based on the three-dimensional Reynolds averaged Navier-Stokes equations is presented in this paper. This approach is a “continuous interface plane approach” where deterministic stresses are used to ensure continuous physical properties across interface planes. The average unsteady effects due to neighboring blades and/or vanes are approximated using deterministic stresses along with the application of bodyforces. Bodyforces are used to account for the “potential” interaction between closely coupled (staged) rows. Deterministic stresses account for the “average” wake blockage and mixing effects both axially and radially. The attempt here is to implement an approximate technique for incorporating periodic unsteady flow physics that provides for a robust multistage design procedure incorporating reasonable computational efficiency. The present paper gives the theoretical development of the stress/bodyforce models incorporated in the code, and demonstrates the usefulness of these models in practical compressor applications. Compressor performance prediction capability is then established through a rigorous code/model validation effort using the power of networked workstations. The numerical results are compared with experimental data in terms of one-dimensional performance parameters such as total pressure ratio and circumferentially averaged radial profiles deemed critical to compressor design. This methodology allows the designer to design from hub to tip with a high level of confidence in the procedure.

Vorticity Dynamics in Axial Compressor Flow Diagnosis and Design

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Yantao Yang ◽  
Hong Wu ◽  
Qiushi Li ◽  
Sheng Zhou ◽  
Jiezhi Wu
Keyword(s):  
Pressure Ratio ◽  
Axial Compressor ◽  
Design Procedure ◽  
Abel Equation ◽  
Navier Stokes ◽  
Design Stage ◽  
Analysis And Design ◽  
Compressor Performance ◽  
Performance Check ◽  
Integrated Performance

It is well recognized that vorticity and vortical structures appear inevitably in viscous compressor flows and have strong influence on the compressor performance. However, conventional analysis and design procedure cannot pinpoint the quantitative contribution of each individual vortical structure to the integrated performance of a compressor, such as the stagnation-pressure ratio and efficiency. We fill this gap by using the so-called derivative-moment transformation, which has been successfully applied to external aerodynamics. We show that the compressor performance is mainly controlled by the radial distribution of azimuthal vorticity, of which an optimization in the through-flow design stage leads to a simple Abel equation of the second kind. The satisfaction of the equation yields desired circulation distribution that optimizes the blade geometry. The advantage of this new procedure is demonstrated by numerical examples, including the posterior performance check by 3D Navier–Stokes simulation.

Performance Investigations of Large Capacity Centrifugal Compressors

1978 ◽  
Author(s):  
H. Mishina ◽  
I. Gyobu
Keyword(s):  
Pressure Ratio ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Design Procedure ◽  
Test Results ◽  
Three Dimensional Flow ◽  
Loss Analysis ◽  
Area Distribution ◽  
Specific Speed ◽  
Sectional Shape

An experimental investigation concerning the optimum relative velocity distribution within impellers, the optimum diffusion ratio of vaned diffusers and the optimum circumferential area distribution, sectional shape of scrolls was carried out using high specific speed shrouded impellers with backward leaning blades. A performance design procedure based on loss analysis and quasi-three-dimensional flow analysis was also developed and modified by introducing experimental results. The design procedure was applied to a 7900-kw four-stage air compressor to demonstrate the usefulness. Field test results of the complete machine showed that the maximum isothermal efficiency was 75 percent with the pressure ratio of 5.96 and the flow rate of 29.3 m3/s.

Optimum Design of Internal Strain-Gage Balances: An Example of Three-Dimensional Shape Optimization

1987 ◽  
Vol 109 (2) ◽  
pp. 257-262 ◽  
Author(s):  
J. W. Hou ◽  
S. L. Twu
Keyword(s):  
Shape Optimization ◽  
Strain Gage ◽  
Three Dimensional ◽  
Design Procedure ◽  
Internal Strain ◽  
Main Body ◽  
Cross Sectional ◽  
Dimensional Shape ◽  
The Cross ◽  
Three Dimensional Shape

Internal strain-gage balances are often applied to measure the aerodynamic loads acting on the aircraft model in the wind-tunnel test. The balance system consists essentially of one main body and two shoulders elastically interconnected by multibar cages. Designing the cross-sectional geometry of such a multibar cage balance to improve the accuracy of load measurement is an important task for a balance engineer. The study presents an initial attempt to carry out such a design task in a systematic and automated manner. This is achieved by considering two aspects. One is to establish a mathematical model to analyze the stress distribution in the elastic cage and the other is to adopt a three-dimensional shape optimization scheme to design the cross-sectional geometry of the internal strain-gage balance. The design procedure has been completely automated in a computer program. Numerical examples shows that the proposed numerical scheme performs very well.

Component-Based Modeling and Sensitivity Analysis of Composite Beam Cross-Sections

2019 ◽  
Author(s):  
Matteo Scapolan ◽  
Valentin Sonneville ◽  
Alfonso Callejo ◽  
Olivier A. Bauchau
Keyword(s):  
Sensitivity Analysis ◽  
Cross Sections ◽  
Three Dimensional ◽  
Real Life ◽  
Adjoint Sensitivity ◽  
Cross Sectional ◽  
Analysis And Design ◽  
Design And Manufacturing ◽  
Slender Bodies ◽  
Sectional Analysis

Abstract Flexible multibody systems often include slender bodies that can be modeled as beams. In contrast with their three-dimensional counterparts, beam formulations are much more efficient and produce models that are more intuitive from engineering and design standpoints. This paper presents a modular approach for the analysis and design of complex beam cross-sections made of heterogeneous and isotropic materials. This approach builds on previous research by the authors, namely research that dealt with cross-sectional analysis and adjoint sensitivity analysis. In addition to the theoretical and software developments, a number of practical examples are shown and verified. The results show that this parametric approach facilitates the definition, analysis and design of complex beam cross-sections, all of which are necessary components in real-life design and manufacturing.

Analysis and Design of Centrifugal Blowers for the Pressure Ratio Range 1.2 - 1.8

2021 ◽  
Author(s):  
Jonathon Howard ◽  
Abraham Engeda
Keyword(s):  
Pressure Ratio ◽  
Tangential Velocity ◽  
Design Procedure ◽  
Diameter Ratio ◽  
Flow Coefficient ◽  
Flow Angle ◽  
Blade Passage ◽  
Analysis And Design ◽  
Specific Speed ◽  
Ratio Range

Abstract Centrifugal/centrifugal compressor designs within pressure ratio range of 2.0–4.0 have well-established guidelines for most common gases, and it is possible to determine optimum compressor geometry for numerous applications as characterized by specific speed or flow coefficient. Specific speed can be correlated to various combinations of inlet tip-exit diameter ratio, inlet hub-tip diameter ratio, blade exit back-sweep, and inlet-tip absolute tangential velocity for solid body pre-whirl. For centrifugal compressors in the pressure ratio range of 1.2–1.8, commonly known as blowers, there lacks organized and systematic optimum design procedures. Blowers, among many others uses, are widely used in HVAC, and provide air for ventilation and industrial process requirements. Due to broad applications in industry, blowers comprise an important sub-group of turbomachinery. This paper provides analysis and design data for blowers in the pressure ratio range of 1.2–1.8. Specific speed is determined from the data provided, and accurate correlations to possible achievable maximum efficiencies are established within a good operational range. Furthermore, plots of impeller exit flow angle, inlet tip-exit diameter ratio, inlet hub-tip diameter ratio, head coefficient, and blade exit back-sweep are provided over a range of specific speeds for various tip speeds to permit rapid selection of optimum blower size and shape for a variety of applications. The design procedure follows a method that enables efficient blade passage sizing. When the blower inlet and outlet velocities, diameters, blade widths, and blade angles are determined and fixed, the blade passage and profile will be sized by applying an energy, momentum, and continuity balance analysis. The application of these equations equates the proper pressure and velocity distribution throughout the blower impeller. Generally, the passage is designed to accommodate an optimum prescribed diffusion rate.

A Review of the History of the NACA Centrifugal Compressor Program and Arrival at Current Computational Design Procedures

2004 ◽  
Author(s):  
Joseph T. Hamrick
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Design Procedure ◽  
Computational Design ◽  
Centrifugal Impeller ◽  
World War ◽  
Design Procedures ◽  
History Of

Before and during World War Il the design and development of single stage, high pressure ratio centrifugal compressors was essentially a cut and try exercise. To reach a high pressure without substantial experimentation required multiple stages of impellers and diffusers with pressure ratios in the two to one range. While such arrangements were satisfactory for commercial use where weight was not a major consideration, they were not suitable for jet engines. The centrifugal compressor for the Whittle engine, the first British jet engine, was developed by trial and error with numerous modifications of the hub-shroud profile. The centrifugal compressor section of the National Advisory Committee for Aeronautics (NACA) designed, built and tested three compressor impellers during and after World War Il. They were part of a program designed to evaluate various blade shapes, but encountered such instabilities at the design pressure ratios that the experimental results led to no definitive conclusions. In 1948 the Centrifugal Compressor Section was given the assignment to further investigate the three impellers. The investigation led to the development of a quasi three dimensional design procedure that eliminated the guesswork from the basic design of a centrifugal impeller. Since the 1948 to 1955 time period over which the procedure was developed, the advances in computers have allowed refinements in the original computational methods. It is the objective of this presentation to review the history of the NACA centrifugal compressor program and efforts that have led to the latest developments in computational design procedures.

scholarly journals Accuracy and Reproducibility of Facial Measurements of Digital Photographs and Wrapped Cone Beam Computed Tomography (CBCT) Photographs

Diagnostics ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 757
Author(s):  
Maged Sultan Alhammadi ◽  
Abeer Abdulkareem Al-mashraqi ◽  
Rayid Hussain Alnami ◽  
Nawaf Mohammad Ashqar ◽  
Omar Hassan Alamir ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Soft Tissue ◽  
Cone Beam Computed Tomography ◽  
High Reliability ◽  
Three Dimensional ◽  
Cone Beam ◽  
Cross Sectional ◽  
Facial Profile ◽  
Digital Photographs ◽  
Gonial Angle

The study sought to assess whether the soft tissue facial profile measurements of direct Cone Beam Computed Tomography (CBCT) and wrapped CBCT images of non-standardized facial photographs are accurate compared to the standardized digital photographs. In this cross-sectional study, 60 patients with an age range of 18–30 years, who were indicated for CBCT, were enrolled. Two facial photographs were taken per patient: standardized and random (non-standardized). The non-standardized ones were wrapped with the CBCT images. The most used soft tissue facial profile landmarks/parameters (linear and angular) were measured on direct soft tissue three-dimensional (3D) images and on the photographs wrapped over the 3D-CBCT images, and then compared to the standardized photographs. The reliability analysis was performed using concordance correlation coefficients (CCC) and depicted graphically using Bland–Altman plots. Most of the linear and angular measurements showed high reliability (0.91 to 0.998). Nevertheless, four soft tissue measurements were unreliable; namely, posterior gonial angle (0.085 and 0.11 for wrapped and direct CBCT soft tissue, respectively), mandibular plane angle (0.006 and 0.0016 for wrapped and direct CBCT soft tissue, respectively), posterior facial height (0.63 and 0.62 for wrapped and direct CBCT soft tissue, respectively) and total soft tissue facial convexity (0.52 for both wrapped and direct CBCT soft tissue, respectively). The soft tissue facial profile measurements from either the direct 3D-CBCT images or the wrapped CBCT images of non-standardized frontal photographs were accurate, and can be used to analyze most of the soft tissue facial profile measurements.

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