Extensive Verification of the Denton New Scheme From the User’s Point of View: Part II—Comparison of Calculated and Experimental Results

1986 ◽  
Vol 108 (2) ◽  
pp. 170-177
Author(s):  
T. Sato ◽  
S. Aoki ◽  
T. Nagayama
Keyword(s):  
Incidence Angle ◽  
Weak Shock ◽  
Point Of View ◽  
Design System ◽  
Viscous Effects ◽  
Suction Surface ◽  
Boundary Layer Interaction ◽  
Short Run ◽  
Inlet Conditions ◽  
Turbine Design

A blade-to-blade flow program incorporated in the computer-aided turbine design system is required to have short run times, robustness, and no limitations. The Denton time-marching method published in 1982 is attractive as it is fast and can handle mixed subsonic-supersonic flows. Calibration of code control variables is discussed in part I. In this paper, the scheme is extensively verified by comparing calculated surface Mach number distributions with experimental data obtained from two-dimensional cascade tests for 23 cascades. For the nozzles, excellent agreement is obtained if the flows are fully subsonic, or transonic with weak shock–boundary layer interaction. For the blades, very good agreement is also obtained if the blades have moderate blade reaction and viscous effects are small. Satisfactory results are obtained for suction surface diffusion, even at off-design inlet conditions, if absolute values of incidence angle are less than 10 deg.

Extensive Verification of the Denton New Scheme From the User’s Point of View: Part I—Calibration of Code Control Variables

1986 ◽  
Vol 108 (2) ◽  
pp. 162-169 ◽  
Author(s):  
T. Sato ◽  
S. Aoki ◽  
T. Nagayama
Keyword(s):  
Point Of View ◽  
Interactive Design ◽  
Design System ◽  
Control Variables ◽  
Factors Affecting ◽  
Know How ◽  
Short Run ◽  
Time Marching ◽  
Entropy Conservation ◽  
Turbine Design

Recently, a computer-aided interactive design system has been used for turbine design. The blade-to-blade flow program incorporated in the system is required to have short run times, robustness, and no limitations. The Denton time-marching code is attractive as it is fast and can handle mixed subsonic–supersonic flows. The Denton new scheme was published in 1982 and improvements were achieved in run times and entropy conservation. In this paper, code control variables are calibrated from the user’s point of view. Factors affecting computing costs and accuracy are investigated, and the “know-how” necessary to operate the code efficiently is discussed. Comparisons of calculated and experimental results are presented in part II.

scholarly journals Pulsed Flow Turbine Design Recommendations

2021 ◽  
Vol 6 (3) ◽  
pp. 24
Author(s):  
Florian Hermet ◽  
Nicolas Binder ◽  
Jérémie Gressier ◽  
Gonzalo Sáez-Mischlich
Keyword(s):  
Design Of Experiments ◽  
Performance Indicator ◽  
Influential Factors ◽  
Factor Level ◽  
Viscous Effects ◽  
Inviscid Flows ◽  
Screening Design ◽  
Pulsed Flow ◽  
Number Of Factors ◽  
Turbine Design

A preliminary analysis of turbine design, fit for pulsed flow, is proposed in this paper. It focuses on an academic 2D configuration using inviscid flows, since pressure loads due to wave propagation are several orders of magnitude higher than friction and viscous effects do not significantly impinge on the inviscid part, as previously shown by Hermet, 2021. As such, a large parametric study was carried out using the design of experiments methodology. A performance indicator adapted to unsteady environment is carefully defined before detailing the factors chosen for the design of experiments. Since the number of factors is substantial, a screening design to identify the factors influence on the output is first established. The non-influential factors are then omitted in a more quantitative study of the output law. The surface response calculation allows determining the factor level favouring the best output. Consequently, the main trends in the turbine design driven by a pulsed flow can be stated.

Comparison of Inviscid Computations With Theory and Experiment in Vibrating Transonic Compressor Cascades

1990 ◽  
Author(s):  
G. A. Gerolymos ◽  
E. Blin ◽  
H. Quiniou
Keyword(s):  
Boundary Layer ◽  
Plate Theory ◽  
Strong Shock ◽  
Acoustic Resonance ◽  
Boundary Layer Separation ◽  
Computational Method ◽  
Viscous Effects ◽  
Transonic Compressor ◽  
Boundary Layer Interaction ◽  
Interaction Regions

The prediction of unsteady flow in vibrating transonic cascades is essential in assessing the aeroelastic stability of fans and compressors. In the present work an existing computational code, based on the numerical integration of the unsteady Euler equations, in blade-to-blade surface formulation, is validated by comparison with available theoretical and experimental results. Comparison with the flat plate theory of Verdon is, globally, satisfactory. Nevertheless, the computational results do not exhibit any particular behaviour at acoustic resonance. The use of a 1-D nonreflecting boundary condition does not significantly alter the results. Comparison of the computational method with experimental data from started and unstarted supersonic flows, with strong shock waves, reveals that, notwithstanding the globally satisfactory performance of the method, viscous effects are prominent at the shock wave/boundary layer interaction regions, where boundary layer separation introduces a pressure harmonic phase shift, which is not presicted by inviscid methods.

“IRIS” A Computerized High Head Pump Turbine Design System

1977 ◽  
Vol 99 (3) ◽  
pp. 567-577
Author(s):  
S. Chacour ◽  
J. E. Graybill
Keyword(s):  
Mechanical Design ◽  
Design Parameters ◽  
Design System ◽  
Performance Requirements ◽  
Manufacturing Process Planning ◽  
Depth Analysis ◽  
High Head ◽  
Critical Components ◽  
Limited Input Data ◽  
Turbine Design

“IRIS” is a computerized design and structural optimization system capable of generating all the major hydraulic and mechanical design parameters of high head pump/turbines from limited input data. The program will size the unit and select the proper hydraulic passage configuration according to performance requirements and optimize the dimensions of all the major components, generate command tapes used by a numerically controlled flame cutter, estimate cost, and issue manufacturing process planning. It also generates finite element models for the “in depth” analysis of critical components.

scholarly journals Dynamic Integrated Model for Assessing Fisheries: Discard Bans as an Implicit Value-Added Tax

2021 ◽  
Author(s):  
Jose Maria Da Rocha ◽  
Javier García-Cutrín ◽  
Maria-Jose Gutiérrez ◽  
Raul Prellezo ◽  
Eduardo Sanchez
Keyword(s):  
Value Added ◽  
Point Of View ◽  
Value Added Tax ◽  
Biological Variables ◽  
A Value ◽  
Long Run ◽  
The Social ◽  
Negative Effect ◽  
Short Run ◽  
The Impact

AbstractIntegrated economic models have become popular for assessing climate change. In this paper we show how these methods can be used to assess the impact of a discard ban in a fishery. We state that a discard ban can be understood as a confiscatory tax equivalent to a value-added tax. Under this framework, we show that a discard ban improves the sustainability of the fishery in the short run and increases economic welfare in the long run. In particular, we show that consumption, capital and wages show an initial decrease just after the implementation of the discard ban then recover after some periods to reach their steady-sate values, which are 16–20% higher than the initial values, depending on the valuation of the landed discards. The discard ban also improves biological variables, increasing landings by 14% and reducing discards by 29% on the initial figures. These patterns highlight the two channels through which discard bans affect a fishery: the tax channel, which shows that the confiscation of landed discards reduces the incentive to invest in the fishery; and the productivity channel, which increases the abundance of the stock. Thus, during the first few years after the implementation of a discard ban, the negative effect from the tax channel dominates the positive effect from the productivity channel, because the stock needs time to recover. Once stock abundance improves, the productivity channel dominates the tax channel and the economic variables rise above their initial levels. Our results also show that a landed discards valorisation policy is optimal from the social welfare point of view provided that incentives to increase discards are not created.

An Experimental Study of Heat Transfer on an Outlet Guide Vane

2014 ◽  
Author(s):  
Chenglong Wang ◽  
Lei Wang ◽  
Bengt Sundén ◽  
Valery Chernoray ◽  
Hans Abrahamsson
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Reynolds Number ◽  
Turbulent Boundary Layer ◽  
Guide Vane ◽  
Incidence Angle ◽  
Boundary Layer Transition ◽  
Transfer Coefficients ◽  
Suction Surface ◽  
Layer Transition

In the present study, the heat transfer characteristics on the suction and pressure sides of an outlet guide vane (OGV) are investigated by using liquid crystal thermography (LCT) method in a linear cascade. Because the OGV has a complex curved surface, it is necessary to calibrate the LCT by taking into account the effect of viewing angles of the camera. Based on the calibration results, heat transfer measurements of the OGV were conducted. Both on- and off-design conditions were tested, where the incidence angles of the OGV were 25 degrees and −25 degrees, respectively. The Reynolds numbers, based on the axial flow velocity and the chord length, were 300,000 and 450,000. In addition, heat transfer on suction side of the OGV with +40 degrees incidence angle was measured. The results indicate that the Reynolds number and incidence angle have considerable influences upon the heat transfer on both pressure and suction surfaces. For on-design conditions, laminar-turbulent boundary layer transitions are on both sides, but no flow separation occurs; on the contrary, for off-design conditions, the position of laminar-turbulent boundary layer transition is significantly displaced downstream on the suction surface, and a separation occurs from the leading edge on the pressure surface. As expected, larger Reynolds number gives higher heat transfer coefficients on both sides of the OGV.

A Strategy for Multi-Point Compressor Blading Using Multi-Objective Optimization

2012 ◽  
Author(s):  
Alireza Fathi ◽  
Abdollah Shadaram ◽  
Mohammad Alizadeh
Keyword(s):  
Incidence Angle ◽  
Optimization Algorithms ◽  
Optimization Techniques ◽  
Design System ◽  
Design Calculation ◽  
Blade Design ◽  
Objective Functions ◽  
Multi Objective ◽  
First Case ◽  
Through Flow

This paper introduces a framework to perform a multi-objective multipoint aerodynamic optimization for an axial compressor blade. This framework considers through-flow design requirements and mechanical and manufacturing constraints. Typically, components of a blade design system include geometry generation tools, optimization algorithms, flow solvers, and objective functions. In particular, optimization algorithms and objective functions are tuned to reduce blade design calculation cost and to match designed blade performance to the through flow design criteria and mechanical and manufacturing constrains. In the present study, geometry parameters of blade are classified to three categories. For each category, a distinct optimization loop is applied. In outer loop, Gradient-based optimization techniques are used to optimize parameters of the second category and a two-dimensional compressible viscous flow code is used to simulate the cascade fluid flow. Surface curvature optimization is carried out in inner loop, and its objective function is defined by integrating the normalized curvature and curvature slope. The genetic algorithm is used to optimize the parameters in the interior loop. To highlight the capabilities of the design method and to develop design know-how, an initial profile is optimized with three different design philosophies. The highest performance improvement in the first case is 15% reduction in loss at design incidence angle. In the second case, 16.5% increase in allowable incidence angle range, improves blade’s performance at off design conditions.

Effects of Freestream Turbulence on the Losses of a Highly-Loaded Compressor Stator Blade

2003 ◽  
Author(s):  
J. W. Douglas ◽  
S.-M. Li ◽  
B. Song ◽  
W. F. Ng ◽  
Toyotaka Sonoda ◽  
...  
Keyword(s):  
Turbulence Intensity ◽  
Flow Separation ◽  
Reynolds Numbers ◽  
Freestream Turbulence ◽  
Suction Surface ◽  
Flow Losses ◽  
Oil Flow ◽  
Oil Flow Visualization ◽  
Inlet Conditions ◽  
High Reynolds

Very little published literature documents the effects of different freestream turbulence intensities on compressor flows at realistically high Reynolds numbers. This paper presents a study of these effects on a transonic, linear, compressor stator cascade. The cascade consisted of high turning stator airfoils that had the camber of 55 degrees. The effects of freestream turbulence intensities of approximately 0.1% (baseline) and 1.6% were examined. Inlet Mach numbers to the cascade were tested from 0.55 to 0.89. Reynolds numbers, based on the inlet conditions and blade chord, varied between 1.0–2.0×106. Inlet flow angles to the cascade ranged from a choking to a stall condition. For the baseline cases, at most positive incidence angles to the cascade, surface oil flow visualization and Schlieren pictures showed a significant flow separation on the suction surface of the blade. Under these conditions, the increase in freestream turbulence from 0.1% to 1.6% significantly reduced the flow losses of the cascade (by as much as 57% in some cases). In other test conditions where no evidence depicted flow separation on the blade, there were no measurable effects on the losses due to the increase in freestream turbulence intensity. In addition, the increase of freestream turbulence intensity also improved the effective operating range of the cascade significantly (e.g., by 46% or higher).

Optimization of Trimaran Design Configuration in Calm and Deep Water

2020 ◽  
Author(s):  
Renato Skejic ◽  
Sverre A. Alterskjær
Keyword(s):  
Deep Water ◽  
Optimization Procedure ◽  
Wave Theory ◽  
Point Of View ◽  
Engineering Practice ◽  
Total Resistance ◽  
Operational Parameters ◽  
Viscous Effects ◽  
Greenhouse Gasses ◽  
Hard Particles

The field of sea based modern shipping activities is constantly seeking for its improvements to achieve the economically justified operational patterns. In the same time, the sea transportation activities also need to satisfy currently imposed and, as well as, upcoming in the near future, safety and ecologically friendly footprint characteristics when it comes to the emission of greenhouse gasses and hard particles [1]. Fulfilment of the stated requirements consequently asks for the determination of certain vessels operational parameters such as the total resistance of a vessel which estimation is frequently carried out for predefined calm and deep-water environmental scenario. Current work is dealing with investigation of the total resistance parameter in calm and deep water for the preselected types of the trimaran ship hull configurations. The total resistance is estimated according to [2] recommended procedure through applicability of the robust and reliable method which is capable to address the problem of wave resistance prediction in calm and deep water. The method has origin in ordinary and modified Michell thin – ship wave theory by considering the viscous effects [3]. The differences between the utilized theories are discussed from the qualitative and quantitative point of view of the obtained results in comparison to the open source available theoretical experimental data and from the perspective of common engineering practice. Finally, based on the above description, the performed total resistance studies are used as a base for formulation of the optimization procedure which may be used in the trimaran vessel preliminary designs in the range of the forward speeds commonly expected during the normal operational life of the investigated trimaran vessel.

scholarly journals The Influence of Flow Rate on the Wake in a Centrifugal Impeller

1982 ◽  
Author(s):  
M. W. Johnson ◽  
J. Moore
Keyword(s):  
Flow Rate ◽  
Incidence Angle ◽  
Three Dimensional ◽  
Stagnation Pressure ◽  
Centrifugal Impeller ◽  
Suction Surface ◽  
Cross Sectional ◽  
Flow Rates ◽  
Pressure Losses ◽  
Compressor Impeller

Three-dimensional flows and their influence on the stagnation pressure losses in a centrifugal compressor impeller have been studied. All 3 mutally perpendicular components of relative velocity and stagnation pressure on 5 cross-sectional planes, between the inlet and outlet of a 1 m dia shrouded impeller running at 500 rpm were measured. Comparisons were made between results for a flow rate corresponding to nearly zero incidence angle and two other flows, with increased and reduced flow rates. These detailed measurements show how the position of separation of the shroud boundary layer moved downstream and the wake’s size decreased, as the flow rate was increased. The wake’s location, at the outlet of the impeller, was also observed to move from the suction surface at the lowest flow rate, to the shroud at higher flow rates.

Sign in / Sign up

Export Citation Format

Share Document