scholarly journals Aerodynamic Analysis of Multistage Turbomachinery Flows in Support of Aerodynamic Design

1999 ◽  
Author(s):  
John J. Adamczyk
Keyword(s):  
Unsteady Flow ◽  
Axial Flow ◽  
Operating Conditions ◽  
Design Environment ◽  
Cfd Simulations ◽  
Average Flow ◽  
Flow Models ◽  
Time Average ◽  
Semi Empirical ◽  
Future Work

This paper summarizes the state of 3D CFD based models of the time average flow field within axial flow multistage turbomachines. Emphasis is placed on models which are compatible with the industrial design environment and those models which offer the potential of providing credible results at both design and off-design operating conditions. The need to develop models which are free of aerodynamic input from semi-empirical design systems is stressed. The accuracy of such models is shown to be dependent upon their ability to account for the unsteady flow environment in multistage turbomachinery. The relevant flow physics associated with some of the unsteady flow processes present in axial flow multistage machinery are presented along with procedures which can be used to account for them in 3D CFD simulations. Sample results are presented for both axial flow compressors and axial flow turbines which help to illustrate the enhanced predictive capabilities afforded by including these procedures in 3D CFD simulations. Finally, suggestions are given for future work on the development of time average flow models.

scholarly journals Aerodynamic Analysis of Multistage Turbomachinery Flows in Support of Aerodynamic Design

1999 ◽  
Vol 122 (2) ◽  
pp. 189-217 ◽  
Author(s):  
John J. Adamczyk
Keyword(s):  
Unsteady Flow ◽  
Axial Flow ◽  
Operating Conditions ◽  
Aerodynamic Design ◽  
Design Environment ◽  
Cfd Simulations ◽  
Flow Models ◽  
Flow Processes ◽  
Design Systems ◽  
Future Work

This paper summarizes the state of 3D CFD based models of the time-averaged flow field within axial flow multistage turbomachines. Emphasis is placed on models that are compatible with the industrial design environment and those models that offer the potential of providing credible results at both design and off-design operating conditions. The need to develop models free of aerodynamic input from semiempirical design systems is stressed. The accuracy of such models is shown to be dependent upon their ability to account for the unsteady flow environment in multistage turbomachinery. The relevant flow physics associated with some of the unsteady flow processes present in axial flow multistage machinery are presented along with procedures that can be used to account for them in 3D CFD simulations. Sample results are presented for both axial flow compressors and axial flow turbines that help to illustrate the enhanced predictive capabilities afforded by including these procedures in 3D CFD simulations. Finally, suggestions are given for future work on the development of time-averaged flow models. [S0889-504X(00)02002-X]

An Investigation of Steady and Unsteady Flow through a Napier Turboblower Turbine under Conditions of Full and Partial Admission

1968 ◽  
Vol 183 (1) ◽  
pp. 615-630 ◽  
Author(s):  
H. R. M. Craig ◽  
K. J. Edwards ◽  
J. H. Horlock ◽  
M. Janota ◽  
R. Shaw ◽  
...  
Keyword(s):  
Unsteady Flow ◽  
Mass Flow ◽  
Power Output ◽  
Axial Flow ◽  
Limited Range ◽  
Expansion Ratio ◽  
Operating Conditions ◽  
Turbine Efficiency ◽  
Cyclic Operation ◽  
Partial Admission

The paper presents the results of tests on an axial-flow turbine and describes how they are obtained, in steady and unsteady flow. An analysis of turbine-test results obtained under the unsteady operating conditions is then given. It is shown that over a limited range of cyclic operation the mass flow and power output may be predicted by assuming that the turbine operates instantaneously as it would under steady-flow conditions (at the same expansion ratio and the same non-dimensional rotational speed) and integrating over the engine cycle. At high pressure ratios, pulse frequencies and rotational speeds, this ‘quasi-steady’ analysis gives a slight overestimate of mass flow and power output but the error in turbine efficiency is very small.

Unsteady Flow Analysis of the Stator-Rotor Interaction in an Axial Flow Fan

2003 ◽  
Author(s):  
J. Ferna´ndez Oro ◽  
K. Argu¨elles Di´az ◽  
C. Santolaria Morros ◽  
R. Ballesteros Tajadura
Keyword(s):  
Unsteady Flow ◽  
Flow Analysis ◽  
Flow Characteristics ◽  
Axial Flow ◽  
3D Models ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Axial Flow Fan ◽  
Rotating Blade ◽  
Flow Phenomena

In the usual operation of turbomachinery, some unsteady flow phenomena appear due to the non uniformity of the flow inside the rotor, when observed in the fixed reference frame. These phenomena are often related to the unsteady character of the pressure and velocity fields, which produce oscillating forces on the blades, superimposed to the steady force. These oscillating forces are the main mechanism of noise generation, which appear even at a constant rotational speed and at flow rates where the performance curves are stable. In axial turbomachines, the interaction is due to relative motion between the static and rotating blade rows. Considering the case of a fixed blade row (stator) placed upstream of the rotor, the non uniform flow leaving those blades (usually referred as IGV blades) is observed as an unsteady flow by the rotor blades. The effect of this interaction is the generation of unsteady forces on the rotor blades, which generate vibrations (risk of fatigue failure) and noise, and non-uniformity and unsteadiness of the pressure field, that propagates as an acoustic wave. The first part of this work is a brief description of a URANS numerical modeling of the unsteady flow characteristics of a one-stage subsonic axial flow fan with a reaction degree greater than 1. The focus is placed on the statorrotor interaction performance. Both 2D and 3D models of the fan, with 13 IGV’s and 9 rotor blades, were developed and an unsteady simulation was achieved to carry out the main characteristics of the flow inside the turbomachine. Once the actuating forces are determined, the influence of the radial position, the operating conditions and the distance of the fixed and the rotating blade rows is also analyzed. The final part of the paper is focused over the identification, through the definition of deterministic stresses — related to the characteristic blade-passage frequency of every row — that provoke the interaction between fixed and rotating blade rows and its evolution through time. The object is to obtain, in a stress tensor form, the contribution of the velocity field, that is changing because of the sucessive relative positions between blade rows, to the pressure distribution over the blade surfaces in the interior of the stage. Finally, a map of deterministic stresses and even, deterministic kinetic energy, can be obtained to show the influence of the blade rows in the interaction, unsteady phenomena.

scholarly journals Through Flow Calculation in Axial Flow Turbines Using a Quasi-Orthogonal Solver

1998 ◽  
Author(s):  
F. Noera ◽  
A. Satta
Keyword(s):  
Numerical Investigation ◽  
Mesh Generation ◽  
Axial Flow ◽  
Operating Conditions ◽  
Flow Solver ◽  
Turbine Performance ◽  
Through Flow ◽  
New Formulation ◽  
High Level ◽  
Semi Empirical

Application of CFD investigating and analysing axial flow turbomachines has reached, in the last years, a high level of accuracy and thus can be applied quite routinely in the prediction of different kinds of flow. The numerical investigation of axial flow turbine performance is of great interest because of the importance of correct product design and of the behaviour in off-design conditions. In this paper a new formulation of the radial equilibrium equation is presented. This formulation is particularly suitable for turbomachinery numerical investigation, and is applied in a quasi-orthogonal through flow solver. All the terms involved in the proposed formulation have been taken into account in order to solve the more general problem. Mesh generation and blade geometrical representation are simplified in order to reduce the pre-processing work. In order to evaluate cascade losses and deviation angle, Ainley- and Mathieson semi-empirical correlations and their correction proposed by Dunham and Came and Kacker and Okapuu have been utilised. The four stages Hannover experimental turbine and the Cambridge one have been analysed in different operating conditions; numerical results have been compared with the experimental ones to evaluate the level of accuracy of the proposed procedure.

Flow Features Analysis of Throttle Notches of Proportional Direct Valve

2011 ◽  
Vol 189-193 ◽  
pp. 2285-2288
Author(s):  
Wen Hua Jia ◽  
Chen Bo Yin ◽  
Guo Jin Jiang
Keyword(s):  
Fluid Flow ◽  
Dynamic Behavior ◽  
Flow Rate ◽  
Discharge Coefficient ◽  
3D Models ◽  
Operating Conditions ◽  
Flow Models ◽  
Flow Features ◽  
Rate Discharge ◽  
Spool Valve

Flow features, specially, flow rate, discharge coefficient and efflux angle under different operating conditions are numerically simulated, and the effects of shapes and the number of notches on them are analyzed. To simulate flow features, 3D models are developed as commercially available fluid flow models. Most construction machineries in different conditions require different actions. Thus, in order to be capable of different actions and exhibit good dynamic behavior, flow features should be achieved in designing an optimized proportional directional spool valve.

Powder Spheroidization Using Induction Plasma Technology

2000 ◽  
Author(s):  
N.M. Dignard ◽  
M.I. Boulos
Keyword(s):  
Energy Efficiency ◽  
Maximum Energy ◽  
Operating Conditions ◽  
Side Reactions ◽  
Induction Plasma ◽  
Silica Alumina ◽  
Change In The Mean ◽  
The Individual ◽  
Semi Empirical ◽  
Objective Being

Abstract An experimental study of the spheroidization efficiency of induction plasma processes was completed. The main objective being to obtain models which could be subsequently used for the prediction of the spheroidization efficiency for various powders and plasma operating conditions. Silica, alumina, chromium oxide and zirconia powders were treated during the experimentation. For the plasma treatment of the powders the installation used had a maximum available power of 50 kW with an operating frequency of 3 MHz. Operating conditions were varied such to minimize side reactions and the evaporation of powders. The resulting powders did show the presence of cavities and a slight change in the mean diameters. The maximum energy efficiency based semi-empirical model did predict the spheroidization efficiency of the particles beyond a defined critical point known as the maximum energy efficiency point. For the model, the maximum energy efficiency is distinct for the individual powders but remain within a defined range which is reflected in the small variations in the Z constant.

Interaction Between Two Closely Spaced Azimuthing Thrusters

1998 ◽  
Vol 42 (01) ◽  
pp. 15-32 ◽  
Author(s):  
Paul Brandner ◽  
Martin Renilson
Keyword(s):  
Mathematical Model ◽  
Satisfactory Agreement ◽  
Vehicle Dynamics ◽  
Operating Conditions ◽  
Towing Tank ◽  
Empirical Relations ◽  
Series Of Experiments ◽  
Flow Effects ◽  
Semi Empirical

To assist in predicting the performance of omni-directional propelled vehicles a series of experiments has been conducted to measure the interaction between two closely spaced ductedazimuthing thrusters. The thrusters were tested below a shallow draft ground board in a towing tank at a spacing of approximately 2 propeller diameters. Measurements were made of forces acting on a single thruster for a range of operating conditions and similarly on two thrusters for a range of relative positions. The results show that forces from the trailing thruster are heavily affected by interaction, particularly due to impingement of the race from the leading thruster, where as forces from the leading thruster remain essentially unaffected despite its proximity to the trailing thruster. A semi-empirical mathematical model suitable for simulation of omni-directional vehicle dynamics is presented. The model is based on the trajectory of the race from the leading thruster derived from momentum considerations with additional empirical relations to account for other more minor flow effects. Comparison of the predicted and measured results show satisfactory agreement.

A Fully Coupled Approach for the Integration of 3D-CFD Component Simulation in Overall Engine Performance Analysis

2017 ◽  
Author(s):  
C. Klein ◽  
S. Reitenbach ◽  
D. Schoenweitz ◽  
F. Wolters
Keyword(s):  
Performance Analysis ◽  
Boundary Conditions ◽  
Progress Monitoring ◽  
Cfd Simulation ◽  
System Simulation ◽  
Pressure Ratio ◽  
Performance Model ◽  
Operating Conditions ◽  
Operating Characteristics ◽  
Design Environment

Due to a high degree of complexity and computational effort, overall system simulations of jet engines are typically performed as 0-dimensional thermodynamic performance analysis. Within these simulations and especially in the early cycle design phase, the usage of generic component characteristics is common practice. Of course these characteristics often cannot account for true engine component geometries and operating characteristics which may cause serious deviations between simulated and actual component and overall system performance. This leads to the approach of multi-fidelity simulation, often referred to as zooming, where single components of the thermodynamic cycle model are replaced by higher-order procedures. Hereby the consideration of actual component geometries and performance in an overall system context is enabled and global optimization goals may be considered in the engine design process. The purpose of this study is to present a fully automated approach for the integration of a 3D-CFD component simulation into a thermodynamic overall system simulation. As a use case, a 0D-performance model of the IAE-V2527 engine is combined with a CFD model of the appropriate fan component. The methodology is based on the DLR in-house performance synthesis and preliminary design environment GTlab combined with the DLR in-house CFD solver TRACE. Both, the performance calculation as well as the CFD simulation are part of a fully automated process chain within the GTlab environment. The exchange of boundary conditions between the different fidelity levels is accomplished by operating both simulation procedures on a central data model which is one of the essential parts of GTlab. Furthermore iteration management, progress monitoring as well as error handling are part of the GTlab process control environment. Based on the CFD results comprising fan efficiency, pressure ratio and mass flow, a map scaling methodology as it is commonly used for engine condition monitoring purposes is applied within the performance simulation. Hereby the operating behavior of the CFD fan model can be easily transferred into the overall system simulation which consequently leads to a divergent operating characteristic of the fan module. For this reason, all other engine components will see a shift in their operating conditions even in case of otherwise constant boundary conditions. The described simulation procedure is carried out for characteristic operating conditions of the engine.

Predictions of Endwall Losses and Secondary Flows in Axial Flow Turbine Cascades

1987 ◽  
Vol 109 (2) ◽  
pp. 229-236 ◽  
Author(s):  
O. P. Sharma ◽  
T. L. Butler
Keyword(s):  
Flow Visualization ◽  
Secondary Flow ◽  
Axial Flow ◽  
Secondary Flows ◽  
Integral Boundary ◽  
Realistic Interpretation ◽  
Proposed Model ◽  
Flow Theories ◽  
Semi Empirical ◽  
End Wall

This paper describes the development of a semi-empirical model for estimating end-wall losses. The model has been developed from improved understanding of complex endwall secondary flows, acquired through review of flow visualization and pressure loss data for axial flow turbomachine cascades. The flow visualization data together with detailed measurements of viscous flow development through cascades have permitted more realistic interpretation of the classical secondary flow theories for axial turbomachine cascades. The re-interpreted secondary flow theories together with integral boundary layer concepts are used to formulate a calculation procedure for predicting losses due to the endwall secondary flows. The proposed model is evaluated against data from published literature and improved agreement between the data and predictions is demonstrated.

Sign in / Sign up

Export Citation Format

Share Document