scholarly journals Off-Design Considerations through the Properties of Some Pressure-Ratio Line of Radial Inflow Turbines

2008 ◽  
Vol 2008 ◽  
pp. 1-8 ◽  
Author(s):  
N. Binder ◽  
X. Carbonneau ◽  
P. Chassaing
Keyword(s):  
Pressure Ratio ◽  
Design Procedure ◽  
Optimization Methods ◽  
Variable Geometry ◽  
Design Concepts ◽  
Recent Developments ◽  
Operating Constraints ◽  
Straight Lines ◽  
Radial Turbines ◽  
Two Machines

Radial turbines are commonly used in applications involving operation through severe off-design conditions. The emergence of variable-geometry systems leads to the distinction between two off-design concepts: operational and geometric off-designs. Both of these operating constraints should be integrated in the design procedure. Recent developments in prediction and optimization methods allowed such an integration, but involving complex algorithms is coupled with semiempiric loss models. This paper provides a basis to obtain simple information from an existing or predesigned machine, for both operational and geometric off-design conditions. An alternative turbine map is defined using loading and flow coefficients. A one-dimensional analysis shows that the constant pressure-ratio lines are straight lines whose slope is remarkably correlated with the pressure-ratio value and geometrical characteristics. This theoretical approach is validated against the experimentation of two machines, the linearity is observed in both cases. The direct influence of the stator configuration on the pressure-ratio lines confirms the applicability of this work to variable-geometry stages. A dimensionless cross-section of the stator is thus defined. However, the unexpected displacement of the intercept of the pressure-ratio lines limits the application field of this method. Nevertheless, a simple performance prediction analysis is proposed for blocked mass flow operation.

scholarly journals Analysis of the Variable Geometry Effect in Radial Turbines

2011 ◽  
Vol 134 (4) ◽  
Author(s):  
Nicolas Binder ◽  
Sebastien Le Guyader ◽  
Xavier Carbonneau
Keyword(s):  
Pressure Ratio ◽  
Point Of View ◽  
Flow Coefficient ◽  
Geometric Configuration ◽  
Theoretical Point ◽  
Variable Geometry ◽  
Geometry Problem ◽  
Points Of View ◽  
Definition Of ◽  
Radial Turbines

The influence of variable geometry stators on the stage behavior is analyzed from both theoretical and experimental points of view. A theoretical analysis of the trajectory of some pressure-ratio lines in a loading-to-flow-coefficient diagram leads to the definition of a specific dimensionless parameter: the reduced section. This parameter is representative of the stator geometric configuration and is thus expected to be a good candidate to describe the variable geometry problem. From a theoretical point of view, this parameter is no less than the formal expression of the link between the geometric configuration of the stator and the behavior of the stage. An experimental approach decomposed in three phases is then led to evaluate this assessment. The results clearly demonstrate the crucial influence of the reduced section in the operating point definition. It leads to the conclusion that from a theoretical point of view, the two solutions mainly used in the industry for variable geometry stages (variation of the height or of the opening position of the stator blades) are equivalent provided that they are sanitized of their respective technological drawbacks. It has also been shown that the geometric configuration of the stator chosen to reach a specific value of the reduced section has some incidence on the efficiency of the stage. This observation gives some opportunities for optimization, for which some axis of reflection is given.

scholarly journals Machine Learning for Design Optimization of Electromagnetic Devices: Recent Developments and Future Directions

2021 ◽  
Vol 11 (4) ◽  
pp. 1627
Author(s):  
Yanbin Li ◽  
Gang Lei ◽  
Gerd Bramerdorfer ◽  
Sheng Peng ◽  
Xiaodong Sun ◽  
...  
Keyword(s):  
Machine Learning ◽  
Design Optimization ◽  
Optimization Methods ◽  
Machine Learning Algorithms ◽  
Cloud Services ◽  
Robust Design Optimization ◽  
Support Vector ◽  
Future Directions ◽  
Electromagnetic Devices ◽  
Recent Developments

This paper reviews the recent developments of design optimization methods for electromagnetic devices, with a focus on machine learning methods. First, the recent advances in multi-objective, multidisciplinary, multilevel, topology, fuzzy, and robust design optimization of electromagnetic devices are overviewed. Second, a review is presented to the performance prediction and design optimization of electromagnetic devices based on the machine learning algorithms, including artificial neural network, support vector machine, extreme learning machine, random forest, and deep learning. Last, to meet modern requirements of high manufacturing/production quality and lifetime reliability, several promising topics, including the application of cloud services and digital twin, are discussed as future directions for design optimization of electromagnetic devices.

Recent Developments in Composite Construction in the USA

2005 ◽  
Vol 8 (3) ◽  
pp. 259-274 ◽  
Author(s):  
Roberto T. Leon
Keyword(s):  
Reinforced Concrete ◽  
Design Procedure ◽  
Concrete Columns ◽  
Short Description ◽  
Smooth Transition ◽  
American Institute ◽  
Recent Developments ◽  
The Usa ◽  
Column Design ◽  
Main Change

This paper presents an overview of the proposed changes in composite design provisions for the upcoming American Institute of Steel Construction (AISC) 2005 Specification. The main change insofar as member design is concerned relates to how composite column design is handled. The new provisions will provide a more smooth transition between design of composite and reinforced concrete columns and a more rational, mechanistically-based design procedure. Insofar as member detailing is concerned, the main change is in the strength values for shear studs, which have been considerably lowered under some circumstances. The paper also presents some ongoing developments in composite floor and lateral load resisting systems, and concludes with a short description of an unusual composite truss.

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.

scholarly journals Preliminary Design Considerations for Variable Geometry Radial Turbines with Multi-Points Specifications

2018 ◽  
Vol 3 (4) ◽  
pp. 22
Author(s):  
Pierre-Thomas Lauriau ◽  
Nicolas Binder ◽  
Sandrine Cros ◽  
Mathieu Roumeas ◽  
Xavier Carbonneau
Keyword(s):  
Flow Diagram ◽  
Speed Ratio ◽  
Preliminary Design ◽  
Variable Geometry ◽  
Operating Range ◽  
Design Considerations ◽  
Radial Turbines ◽  
Nozzle Opening

Radial turbines’ preliminary designs are usually carried out through some dimensionless approaches, such as the loading-to-flow-diagram and/or the blade speed ratio. In case of variable nozzle radial turbines, multi-points specifications must be considered, related to the improvement of the operating range. As preliminary design correlations and standards usually taken into consideration arise from studies dedicated to fixed geometry radial turbines, they need to be updated with regard to nozzle off-design opening configurations. This paper provides some theoretical basics in order to help designers considering variable geometry problems. Some complementary elements about the dimensionless methods are given by taking into account the nozzle opening effect. Then, useful considerations are brought regarding the preliminary design of variable geometry radial turbines with multi-points specifications.

Paper 7: Review of Porous Metal Bearing Developments

1965 ◽  
Vol 180 (11) ◽  
pp. 154-159
Author(s):  
P. R. Marshall ◽  
V. T. Morgan
Keyword(s):  
Hydrodynamic Lubrication ◽  
Design Procedure ◽  
Porous Metal ◽  
Design Criterion ◽  
Gas Content ◽  
Low Permeability ◽  
Eccentricity Ratio ◽  
Practical Design ◽  
Recent Developments ◽  
And Performance

Recent developments aimed at increasing the life and performance of porous metal bearings have included a double layer bearing of low permeability, porous aluminium for better heat conductivity, ultrasonic cleaning of the porous surface, and the possible use of synthetic oils for improved oxidation resistance. The interactions between the porosity and the oil in terms of the surface tension, the effects of gas content on viscosity and permeability, and the rate of oil loss and reabsorption, are discussed in relation to these developments. A better understanding of the mechanisms involved leads to a practical design criterion for the limit of hydrodynamic lubrication of porous bearings of finite L/d ratio based on an eccentricity ratio of 0.8 and the difficulties of determining the appropriate value of permeability required for a more rigorous design procedure are outlined, together with suggested work for overcoming them.

Mean-Line Modelling of a Variable Geometry Turbocharger (VGT) and Prediction of the Engine-Turbocharger Coupled Performance

2017 ◽  
Author(s):  
Anand Mammen Thomas ◽  
Jensen Samuel ◽  
A. Ramesh
Keyword(s):  
Pressure Ratio ◽  
Operating Conditions ◽  
Relaxation Techniques ◽  
Variable Geometry ◽  
Test Bed ◽  
Variable Geometry Turbocharger ◽  
Initial Assumption ◽  
Blockage Factor ◽  
Pressure Boundary Condition ◽  
Variable Geometry Turbine

Mean-line modelling approach which has generally been applied to fixed geometry turbocharger turbines has been extended to predict the performance of the variable geometry turbine for different inlet blade angles. The model uses an initial assumption of turbine inlet pressure which was iteratively corrected based on outlet pressure boundary condition. The model was implemented in MATLAB and stable and convergent solutions were obtained using relaxation techniques for different operating conditions. Experiments were done on a state of the art transient diesel engine test bed using the same VGT turbine in the turbocharger at different engine torques and speeds. Using experimental data the model was calibrated for the aerodynamic blockage in the fixed nozzle and rotor blade passages. Results revealed that turbine overall pressure ratio can be predicted accurately if a blockage factor varying with nozzle blade orientation is used in the model.

Investigation of a Variable Geometry Turbine Nozzle for Diesel Engine Turbochargers

2019 ◽  
Author(s):  
Anuj Srivastava ◽  
Kuldeep Kumar ◽  
Ganesh Banda
Keyword(s):  
Pressure Ratio ◽  
Boost Pressure ◽  
Variable Geometry ◽  
Efficient Design ◽  
Performance Variation ◽  
High Efficient ◽  
Emission Regulations ◽  
Variable Geometry Turbine ◽  
Potential Benefits ◽  
Wide Operating

Abstract High power demand, emission regulations, high efficient design are the prime requirement for the design of turbochargers. VGT (variable geometry turbocharging) is most widely used and explored compared to other available options to deal with today’s market. VGT turbochargers offers several potential benefits when compared to fixed geometry turbochargers, like increased transient response, wide operating range, improved torque characteristics, boost pressure recovery and better fuel economy. In this paper performance variation of compressor and turbine viz, — Pressure ratio, mass flow, and efficiency, and throat area are optimized to reach to the operating point of the engine. Different vane angles (0, +4°, +7°, +10° & +15°) are studied to understand the variation of transient turbine response. Authors also discussed the mechanical conceptualization of the VANT (Variable area nozzle) in thought of having great impact on the performance.

scholarly journals The Effect of Variable Geometry on the Operating Range and Surge Margin of a Centrifugal Compressor

1976 ◽  
Author(s):  
A. Whitfield ◽  
F. J. Wallace ◽  
R. C. Atkey
Keyword(s):  
Centrifugal Compressor ◽  
Peak Pressure ◽  
Pressure Ratio ◽  
Variable Geometry ◽  
Vaneless Diffuser ◽  
Flow Rates ◽  
Lower Flow ◽  
Operating Range ◽  
Surge Margin ◽  
Isentropic Efficiency

Two variable geometry techniques have been applied to a small turbocharger compressor, with the objective of trying to move the peak pressure ratio operating point to lower flow rates, thereby yielding a broad flow range map. Variable prewhirl guide vanes and variable vaneless diffuser passage height have been studied separately. The results obtained with both techniques are compared and the relative merits and demerits with respect to improved flow range and isentropic efficiency penalties are considered.

Design and Test of a Transonic Axial Splittered Rotor

2015 ◽  
Author(s):  
Garth V. Hobson ◽  
Anthony J. Gannon ◽  
Scott Drayton
Keyword(s):  
Mass Flow ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Design Procedure ◽  
Tip Clearance ◽  
Turbine Engine ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Transonic Axial Compressor ◽  
Commercial Off The Shelf

A new design procedure was developed that uses commercial-off-the-shelf software (MATLAB, SolidWorks, and ANSYS-CFX) for the geometric rendering and analysis of a transonic axial compressor rotor with splitter blades. Predictive numerical simulations were conducted and experimental data were collected in a Transonic Compressor Rig. This study advanced the understanding of splitter blade geometry, placement, and performance benefits. In particular, it was determined that moving the splitter blade forward in the passage between the main blades, which was a departure from the trends demonstrated in the few available previous transonic axial compressor splitter blade studies, increased the mass flow range with no loss in overall performance. With a large 0.91 mm (0.036 in) tip clearance, to preserve the integrity of the rotor, the experimentally measured peak total-to-total pressure ratio was 1.69 and the peak total-to-total isentropic efficiency was 72 percent at 100 percent design speed. Additionally, a higher than predicted 7.5 percent mass flow rate range was experimentally measured, which would make for easier engine control if this concept were to be included in an actual gas turbine engine.

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