Efficient Steady and Unsteady Flow Modeling for Arbitrarily Mis-Staggered Bladerow Under Influence of Inlet Distortion

Commercial Solver

Abstract Accurate and efficient predictions of the steady and unsteady flow responses due to the blade-to-blade variation as well as due to the non-axisymmetric inlet distortion have been continually pursued. Computation of two problems concurrently has been rarely done in the past partly because of the need to perform whole annulus bladerow simulations, despite the advances in the current state-of-the-art methods with the phaseshift single passage simulations. The current work attempts to deal with this challenge by developing a new computational approach based on the principle of the multiscale method in the framework of a commercial solver (CFX). The methodology formulation relies on summation of the constituent source terms, each of which corresponds to a particular flow perturbation. The source term element corresponding to the blade-to-blade variation effect is linearly superimposed as in the classical Influence Coefficient Method. Only the relative positions between the reference blade and its neighbor matter in this method, thus enables an arbitrarily mis-staggered bladerow to be computed efficiently. In addition, the source term arisen due to the inlet distortion is calculated based on spatial Fourier transform. A key enabler is that the source term can be pre-computed using a small set of identical blade passages. The source term is then propagated to different spatial and temporal locations depending on the combination of the mis-staggering pattern and the inlet distortion. The multiscale treatment makes it possible to predict a high-resolution flow field effects on the base coarse mesh as if the fine mesh is solved, while achieving a computational gain. The source term summation method proposed in the current work has been validated using a uniformly staggered bladerow, and an arbitrarily mis-staggered bladerow in a clean inflow condition as well as that subject to an inlet distortion.

Efficient Steady and Unsteady Flow Modeling for Arbitrarily Mis-Staggered Bladerow Under Influence of Inlet Distortion

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4050364 ◽

2021 ◽

Vol 143 (7) ◽

Author(s):

H. M. Phan ◽

L. He

Keyword(s):

Flow Field ◽

Unsteady Flow ◽

Source Term ◽

Time Instant ◽

Influence Coefficient ◽

Efficiency Gain ◽

Source Terms ◽

Flow Perturbation ◽

Inlet Distortion ◽

Fine Mesh

Abstract Accurate and efficient predictions of the steady and unsteady flow responses due to the blade-to-blade variation as well as due to the nonaxisymmetric inlet distortion have been continually pursued. Computation of two problems concurrently has been rarely done in the past partly because of the need to perform whole annulus bladerow simulations, despite the advances in the current state-of-the-art methods with the phase-shift single passage simulations. The current work attempts to deal with this challenge by developing a new computational approach based on the principle of the multiscale method in the framework of a commercial solver (CFX). The methodology formulation relies on summation of the constituent source terms, each of which corresponds to a particular flow perturbation. The source term element corresponding to the blade-to-blade variation effect is linearly superimposed as in the classical Influence Coefficient Method. The unsteady flow field around a blade at any time instant depends only on its relative position to all its neighboring blades, so that the influences of an arbitrarily mis-staggered bladerow can be computed efficiently. In addition, the source term arisen due to the inlet distortion is calculated based on the spatial Fourier transform. A key enabler is that the source terms can be precomputed using a small set of identical blade passages. The source term is then propagated to different spatial and temporal locations depending on the combination of the mis-staggering pattern and the inlet distortion. The multiscale treatment makes it possible to predict a high-resolution flow field effects on the base coarse mesh as if a fine mesh were locally solved, while achieving a considerable computational efficiency gain. The proposed influence-coefficient and source term based method has been validated for test cases with a uniformly staggered bladerow, and for an arbitrarily mis-staggered bladerow, under a clean inflow condition as well as that subject to an inlet distortion.

Unsteady Flow in Oscillating Turbine Cascades: Part 2—Computational Study

Journal of Turbomachinery ◽

10.1115/1.2841402 ◽

1998 ◽

Vol 120 (2) ◽

pp. 269-275 ◽

Cited By ~ 9

Author(s):

L. He

Keyword(s):

Unsteady Flow ◽

Flow Separation ◽

Computational Study ◽

Flow Behavior ◽

Numerical Test ◽

Computational Method ◽

Influence Coefficient ◽

Turbine Cascade ◽

Unsteady flow around a linear oscillating turbine cascade has been experimentally and computationally studied, aimed at understanding the bubble type of flow separation and examining the predictive ability of a computational method. It was also intended to check the validity of the linear assumption under an unsteady viscous flow condition. Part 2 of the paper presents a computational study of the experimental turbine cascade that was discussed in Part 1. Numerical calculations were carried out for this case using an unsteady Navier–Stokes solver. The Baldwin–Lomax mixing length model was adopted for turbulence closure. The boundary layers on blade surfaces were either assumed to be fully turbulent or transitional with the unsteady transition subject to a quasi-steady laminar separation bubble model. The comparison between the computations and the experiment was generally quite satisfactory, except in the regions with the flow separation. It was shown that the behavior of the short bubble on the suction surface could be reasonably accounted for by using the quasi-steady bubble transition model. The calculation also showed that there was a more apparent mesh dependence of the results in the regions of flow separation. Two different kinds of numerical test were carried out to check the linearity of the unsteady flow and therefore the validity of the influence coefficient method. First, calculations using the same configurations as in the experiment were performed with different oscillating amplitudes. Second, calculations were performed with a tuned cascade model and the results were compared with those using the influence coefficient method. The present work showed that the nonlinear effect was quite small, even though for the most severe case in which the separated flow region covered about 60 percent of blade pressure surface with a large movement of the reattachment point. It seemed to suggest that the linear assumption about the unsteady flow behavior should be adequately acceptable for situations with bubble-type flow separation similar to the present case.

Volume 5: Manufacturing Materials and Metallurgy; Ceramics; Structures and Dynamics; Controls, Diagnostics and Instrumentation; Education; General ◽

Unsteady Flow in Oscillating Turbine Cascade: Part 2 — Computational Study

10.1115/96-gt-375 ◽

1996 ◽

Author(s):

L. He

Keyword(s):

Unsteady Flow ◽

Flow Separation ◽

Computational Study ◽

Separation Bubble ◽

Computational Method ◽

Influence Coefficient ◽

Turbine Cascade ◽

Suction Surface ◽

Unsteady flow around a linear oscillating turbine cascade has been experimentally and computationally studied, aimed at understanding the bubble type of flow separation and examining the predictive ability of a computational method. It was also intended to check the validity of the linear assumption under an unsteady viscous flow condition. Part 2 of the paper presents a computational study of the experimental turbine cascade as discussed in Part 1. Numerical calculations were carried out for this case using an unsteady Navier-Stokes solver. The Baldwin-Lomax mixing length model was adopted for turbulence closure. The boundary layers on blade surfaces were either assumed to be fully turbulent or transitional with the unsteady transition subject to a quasi-steady laminar separation bubble model. The comparison between the computations and the experiment were generally quite satisfactory, except in the regions with the flow separation. It was shown that the behaviour of the short-bubble on the suction surface could be reasonably accounted for by using the quasi-steady bubble transition model. The calculation also showed that there was a more apparent mesh dependence of the results in the regions of flow separation. Two different kinds of numerical tests were carried out to check the linearity of the unsteady flow and therefore the validity of the Influence Coefficient method. Firstly calculations using the same configurations as in the experiment were performed with different oscillating amplitudes. Secondly calculations were performed with a tuned cascade model and the results were compared with those using the Influence Coefficient method. The present work showed that nonlinear effect was quite small, even though for the most severe case in which the separated flow region covered about 60% of blade pressure surface with a large movement of the reattachment point. It seemed to suggest that the linear assumption about the unsteady flow behaviour should be adequately acceptable for situations with bubble type flow separation similar to the present case.

Influence Coefficients Obtained by Hammer Beat Permit Significant Time Savings When Balancing Simple Flexible Rotors

Volume 7A: 17th Biennial Conference on Mechanical Vibration and Noise ◽

10.1115/detc99/vib-8260 ◽

1999 ◽

Author(s):

D. Wiese ◽

M. Breitwieser

Keyword(s):

Influence Coefficient ◽

Significant Time ◽

Flexible Rotors ◽

Influence Coefficients ◽

Flexible Roll ◽

Time Savings ◽

Positive Results ◽

Abstract The following paper presents a method for balancing simple flexible rotors with the help of influence coefficients obtained by hammer beat. The method permits time savings of approx. 50% compared to the conventional influence coefficient method. Initial positive results obtained on a flexible roll are also presented.

2018 4th International Conference on Green Technology and Sustainable Development (GTSD) ◽

Study on the Applicability of Influence Coefficient Method Combined with Vector Analysis in Dynamic Balancing Rigid Rotor Using Flexible Supports

10.1109/gtsd.2018.8595685 ◽

2018 ◽

Cited By ~ 1

Author(s):

Lam Tran Thanh ◽

Ngon Dang Thien ◽

Cuong Le Chi

Keyword(s):

Vector Analysis ◽

Influence Coefficient ◽

Rigid Rotor ◽

Dynamic Balancing ◽

Flexible Supports ◽

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

Prototype design and size optimization of a hybrid lower extremity exoskeleton with a scissor mechanism for load-carrying augmentation

10.1177/0954406214532078 ◽

2014 ◽

Vol 229 (1) ◽

pp. 155-167 ◽

Cited By ~ 4

Author(s):

Yunjie Miao ◽

Feng Gao ◽

Dalei Pan

Keyword(s):

Lower Extremity ◽

Influence Coefficient ◽

Input And Output ◽

Flexion Extension ◽

Load Carrying ◽

Prototype Design ◽

Coefficient Method ◽

Length Optimization ◽

Scissor Mechanism

A hybrid lower extremity exoskeleton SJTU-EX which adopts a scissor mechanism as the hip and knee flexion/extension joint is proposed in Shanghai Jiao Tong University to augment load carrying for walking. The load supporting capabilities of a traditional serially connected mechanism and the scissor mechanism are compared in detail. The kinematic influence coefficient method of the kinematic and dynamic analysis is applied in the length optimization of the scissor sides to minimize the transmitting errors between the input and output motions in walking and the load capacities of different scissor mechanisms are illustrated. The optimization results are then verified by the walking simulations. Finally, the prototype of SJTU-EX is implemented with several improvements to enhance the working performances.

NCSXRF: A General Geometry Monte Carlo Simulation Code for EDXRF Analysis

Advances in X-ray Analysis ◽

10.1154/s037603080001291x ◽

1991 ◽

Vol 35 (B) ◽

pp. 727-736 ◽

Cited By ~ 2

Author(s):

T. He ◽

R. P. Gardner ◽

K. Verghese

Keyword(s):

Least Square ◽

Influence Coefficient ◽

Standard Samples ◽

Simulation Code ◽

X Ray ◽

Fundamental Parameters ◽

Edxrf Analysis ◽

Energy Pulse

EDXRF analysis is conveniently split into two parts: (1) the determination of X-ray intensities and (2) the determination of elemental amounts from X-ray intensities. For the first, most EDXRF analysis has been done by some method of integrating the essentially Gaussian distribution of observed full energy pulse heights. This might be done, for example, by least-square fitting of Gaussian distributions superimposed on a straight line or a quadratic background. Recently more elaborate shapes of the energy peaks also have been considered (Kennedy, 1990). After the X-ray intensities have been determined, interelement effects between the analyte element and other elements must be corrected for in order to obtain the elemental amounts from X-ray intensities. This correction can be done either by an empirical correction procedure as in the influence coefficient method which requires measurements on a number of standard samples to determine the required coefficients, or by theoretical calculation as in the fundamental parameters method which does not require standard samples.

A method to select correcting faces of a double-face dynamic balancing rotor

Advances in Mechanical Engineering ◽

10.1177/1687814016682892 ◽

2016 ◽

Vol 8 (12) ◽

pp. 168781401668289

Author(s):

Shihai Zhang ◽

Zimiao Zhang

Keyword(s):

Influence Coefficient ◽

Axial Distribution ◽

Dynamic Balancing ◽

The Real ◽

Influence Coefficients ◽

Total Phase ◽

Phase Variations ◽

Distribution Laws ◽

Design And Practice

Considering the sensitivity and installing position limitation, the real positions for two correcting faces must be selected first in the process of double-face dynamic balancing design and practice for rigid rotor system. According to the principle of influence coefficient method, series of testing weight experiments are conducted in this article. Based on the experimental results, the axial distribution laws of the amplitudes and phases of influence coefficients are found and summarized as follows: the amplitude variations of influence coefficients are very small and the phase variations of influence coefficients are obvious when the correcting positions are changed along shaft, so the phases of influence coefficients have the key effect on the correcting vector in correcting faces. Based on this fact, the total phase difference maximum method of influence coefficients is proposed to select the real axial positions for correcting faces. The principle of the method is analyzed in theory, and the application effect is tested by double-face dynamic balancing experiments.

Study on the Field Dynamic Balance of Diesel Engine Crankshaft

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.307.299 ◽

2013 ◽

Vol 307 ◽

pp. 299-303

Author(s):

Shi Xun Jiang ◽

Shi Hai Zhang ◽

Zhi Min Yu

Keyword(s):

Diesel Engine ◽

Dynamic Balance ◽

Least Square Method ◽

Least Square ◽

Vibration Monitoring ◽

Influence Coefficient ◽

Balance System ◽

Field Dynamic ◽

Engine Crankshaft

Abstract：Based on the actual situations of diesel engines, significance of dynamic balance for marine diesel engine crankshaft system is discussed and as well vibration monitoring and field dynamic balance system for diesel engine crankshaft system is constructed. The least square method is applied to fit fundamental frequency vibration signals of crankshaft system and the field dynamic balance strategy is designed on the basis of the influence coefficient method. The feasibility of the dynamic balance system is tested through experiments in the paper.