Space–Time Gradient Method for Unsteady Bladerow Interaction—Part II: Further Validation, Clocking, and Multidisturbance Effect

2015 ◽  
Vol 137 (12) ◽  
Author(s):  
L. He ◽  
J. Yi ◽  
P. Adami ◽  
L. Capone
Keyword(s):  
Case Studies ◽  
Flow Analysis ◽  
Space Time ◽  
Inlet Temperature ◽  
Turbine Stage ◽  
Two Stage ◽  
Transonic Compressor ◽  
Surface Time ◽  
Blade Row ◽  
Speed Up

For efficient and accurate unsteady flow analysis of blade row interactions, a space–time gradient (STG) method has been proposed. The development is aimed at maintaining as many modeling fidelities (the interface treatment in particular) of a direct unsteady time-domain method as possible while still having a significant speed-up. The basic modeling considerations, main method ingredients and some preliminary verification have been presented in Part I of the paper. Here in Part II, further case studies are presented to examine the capability and applicability of the method. Having tested a turbine stage in Part I, here we first consider the applicability and robustness of the method for a three-dimensional (3D) transonic compressor stage under a highly loaded condition with separating boundary layers. The results of the STG solution compare well with the direct unsteady solution while showing a speed up of 25 times. The method is also used to analyze rotor–rotor/stator–stator interferences in a two-stage turbine configuration. Remarkably, for stator–stator and rotor–rotor clocking analyses, the STG method demonstrates a significant further speed-up. Also interestingly, the two-stage case studies suggest clearly measurable clocking dependence of blade surface time-mean temperatures for both stator–stator clocking and rotor–rotor clocking, though only small efficiency variations are shown. Also validated and illustrated is the capacity of the STG method to efficiently evaluate unsteady blade forcing due to the rotor–rotor clocking. Considerable efforts are directed to extending the method to more complex situations with multiple disturbances. Several techniques are adopted to decouple the disturbances in the temporal terms. The developed capabilities have been examined for turbine stage configurations with inlet temperature distortions (hot streaks), and for three blade-row turbine configurations with nonequal blade counts. The results compare well with the corresponding direct unsteady solutions.

Space-Time Gradient Method for Unsteady Bladerow Interaction: Part II — Further Validation, Clocking and Multi-Disturbance Effect

2015 ◽  
Author(s):  
L. He ◽  
J. Yi ◽  
P. Adami ◽  
L. Capone
Keyword(s):  
Flow Analysis ◽  
Space Time ◽  
Inlet Temperature ◽  
Turbine Stage ◽  
Transonic Compressor ◽  
Surface Time ◽  
Blade Row ◽  
Speed Up ◽  
Unsteady Flow Analysis ◽  
Interface Treatment

For efficient and accurate unsteady flow analysis of blade row interactions, a Space-Time Gradient (STG) method has been proposed. The development is aimed at maintaining as many modelling fidelities (the interface treatment in particular) of a direct unsteady method as possible while still having a significant speed-up. The basic modelling considerations, main method ingredients and some preliminary verification have been presented in Part I by Yi and He [1]. In Part II, further case studies are presented to examine the capability and applicability of the method. Having tested a turbine stage in Part I, here we first consider the applicability and robustness of the method for a 3D transonic compressor stage under a highly loaded condition with separating boundary layers. The results of the STG solution compare well with the direct unsteady solution while showing a speed up of 25 times. Attention is then directed to rotor-rotor/stator-stator interferences in a 2-stage turbine configuration. Remarkably for stator-stator and rotor-rotor clocking analyses, the STG method demonstrates a significant further speed-up. Also interestingly the 2-stage cases studied suggest a clearly measurable clocking dependence of blade surface time-mean temperatures for both stator-stator clocking and rotor-rotor clocking, though only small efficiency variations are indicated. Also validated and illustrated is the capability of the STG for efficient evaluations of unsteady blade forcing due to the rotor-rotor clocking. Considerable efforts are directed to extending the method to more complex situations with multiple-disturbances. Several techniques are adopted to decouple the disturbances in the temporal term. The developed capabilities have been examined for turbine stage configurations with inlet temperature distortions (hot streaks), and for 3 blade-row turbine configurations with non-equal blade counts. The results compare well with the corresponding direct unsteady solutions.

Design Details of a 600 MW Graz Cycle Thermal Power Plant for CO2 Capture

2008 ◽  
Author(s):  
H. Jericha ◽  
W. Sanz ◽  
E. Go¨ttlich ◽  
F. Neumayer
Keyword(s):  
Vortex Flow ◽  
Pressure Ratio ◽  
Thermal Power ◽  
Inlet Temperature ◽  
Turbine Stage ◽  
Turbine Inlet Temperature ◽  
Coal Gas ◽  
Transonic Compressor ◽  
Steam Cooling ◽  
Important Design

The high power highest efficiency zero-emission Graz Cycle plant of 400 MW was presented at ASME IGTI conference 2006 and at CIMAC conference 2007. In continuation of these works a raise of power output to 600 MW is presented and important design details are discussed. The cycle pressure ratio is increased from 40 to 50 bar by a half-speed stage connected via gears to the main compressor shaft allowing to keep the volume flow to the main compressors constant. The compressors are driven by the transonic compressor turbine stage. Mass flow to the compressors is increased by the factor of 1.27, density in blades of the main compressors is raised by the same factor. The turbine inlet temperature is raised to 1500°C together with the increase in the cycle pressure ratio, both are well accepted values in gas turbine technology today. Most important development problems have to be solved in designing the oxy-fuel burners. They are presented here in the form of coaxial jets of fuel (natural gas or coal gas alternatively) held together by a steam vortex providing coherent flow and flame is ignited by its strong suction. Combustion is finalized by the mixing with a counter-rotating outer vortex flow of working gas leading to a well defined position of vortex break down. The transonic stage of the compressor turbine is supplied with innovative steam cooling forming coherent layers outside of the blade shell of which stress deliberations will be presented.

Paper 20: Detailed Flow Measurements in an Experimental Two-Stage Transonic Compressor

1969 ◽  
Vol 184 (7) ◽  
pp. 57-65
Author(s):  
R. K. Oldham
Keyword(s):  
Pressure Loss ◽  
Design Method ◽  
Pressure Ratio ◽  
Axisymmetric Flow ◽  
Performance Characteristics ◽  
Two Stage ◽  
Flow Measurements ◽  
Transonic Compressor ◽  
Blade Row ◽  
Overall Performance

A high duty research compressor has been manufactured which is large enough (34-in first rotor tip diameter) to yield valid results from traverses between the blade rows. The compressor is designed to operate at a first rotor tip speed of 1390 ft/s, produce a pressure ratio of 1·88, and pass a flow of 42·3 lb/s ft2 annulus area. A brief outline of the design method is given and the measured overall performance characteristics are presented. The results from the inter-blade row traverses are compared with the design profiles as predicted by axisymmetric flow calculations. Analysis of the traverse data has produced information on blockage factors, incidence, deviation, and pressure loss which will be useful in the design of other transonic compressors.

Characterization of Deterministic Correlations for a Turbine Stage: Part 1 — Time-Averaged Flow Analysis

1999 ◽  
Author(s):  
Fabien Bardoux ◽  
Francis Leboeuf ◽  
Cédric Dano ◽  
Clément Toussaint
Keyword(s):  
Flow Analysis ◽  
Time Dependent ◽  
Turbine Stage ◽  
Direct Computation ◽  
Correlation Models ◽  
Blade Row ◽  
Transonic Turbine ◽  
Physical Phenomena ◽  
Blade Row Interaction

This paper analyses the flow in a transonic turbine stage, using time-dependent numerical results. Unsteady blade-row interaction has repercussions on the time-averaged flow, which are represented by the so-called “deterministic correlations”. These correlations appear in the system of equations governing the time-averaged flow; they can be divided into four types with different physical meanings. Time-dependent results enable direct computation of these correlations in both rotor and stator frames of reference. The computed deterministic correlations are analysed in the paper, in order to bind them to physical phenomena and to evaluate their influence on the time-averaged flow field. This analysis is also intended to help assess the shortcomings of simple mixing-plane methods and more complex approaches using deterministic correlation models. While the first part focuses on one particular type of deterministic correlation, the so-called “spatial correlation”, the second part attempts a more detailed analysis of time-dependent results and gives some clues to the orders of magnitude of the four types of deterministic correlation. The conclusions should be taken with caution; they may partly depend on the present turbine configuration with a specified structure of unsteadiness and on the present turbulence model.

A two-stage design optimization framework for multifield origami-inspired structures

2021 ◽  
pp. 1045389X2110116
Author(s):  
Wei Zhang ◽  
Saad Ahmed ◽  
Jonathan Hong ◽  
Zoubeida Ounaies ◽  
Mary Frecker
Keyword(s):  
Case Studies ◽  
Computing Time ◽  
Computational Cost ◽  
High Fidelity ◽  
Fe Model ◽  
Two Stage ◽  
Baseline Design ◽  
Optimization Framework ◽  
Highly Nonlinear ◽  
Stage 1

Different types of active materials have been used to actuate origami-inspired self-folding structures. To model the highly nonlinear deformation and material responses, as well as the coupled field equations and boundary conditions of such structures, high-fidelity models such as finite element (FE) models are needed but usually computationally expensive, which makes optimization intractable. In this paper, a computationally efficient two-stage optimization framework is developed as a systematic method for the multi-objective designs of such multifield self-folding structures where the deformations are concentrated in crease-like areas, active and passive materials are assumed to behave linearly, and low- and high-fidelity models of the structures can be developed. In Stage 1, low-fidelity models are used to determine the topology of the structure. At the end of Stage 1, a distance measure [Formula: see text] is applied as the metric to determine the best design, which then serves as the baseline design in Stage 2. In Stage 2, designs are further optimized from the baseline design with greatly reduced computing time compared to a full FEA-based topology optimization. The design framework is first described in a general formulation. To demonstrate its efficacy, this framework is implemented in two case studies, namely, a three-finger soft gripper actuated using a PVDF-based terpolymer, and a 3D multifield example actuated using both the terpolymer and a magneto-active elastomer, where the key steps are elaborated in detail, including the variable filter, metrics to select the best design, determination of design domains, and material conversion methods from low- to high-fidelity models. In this paper, analytical models and rigid body dynamic models are developed as the low-fidelity models for the terpolymer- and MAE-based actuations, respectively, and the FE model of the MAE-based actuation is generalized from previous work. Additional generalizable techniques to further reduce the computational cost are elaborated. As a result, designs with better overall performance than the baseline design were achieved at the end of Stage 2 with computing times of 15 days for the gripper and 9 days for the multifield example, which would rather be over 3 and 2 months for full FEA-based optimizations, respectively. Tradeoffs between the competing design objectives were achieved. In both case studies, the efficacy and computational efficiency of the two-stage optimization framework are successfully demonstrated.

Unsteady Flow Analysis and Vibratory Stress Predictions for a High Work Single Stage Turbine Blade

2012 ◽  
Author(s):  
Kurt Weber ◽  
Girish Modgil ◽  
Steve Gegg ◽  
Shyam Neerarambam ◽  
Moujin Zhang
Keyword(s):  
Flow Field ◽  
Strain Gauge ◽  
Flow Analysis ◽  
Forced Response ◽  
Single Stage ◽  
Turbine Stage ◽  
Rotating Blade ◽  
Gauge Data ◽  
Unsteady Flow Analysis ◽  
High Work

The flow field in High-Work Single-Stage (HWSS) turbines differs from traditional turbine flow fields. Operating at increased pressure ratios, wakes and trailing edge shocks at the exit of the vane are more likely to cause a vibratory response in the rotating blade. This flow field can produce increased excitation at harmonics that correspond to the vane passing frequency and harmonics higher than the vane passing frequency. In this paper, blade vibratory stresses in a HWSS gas turbine stage are predicted using unsteady pressures from two Rolls-Royce in-house flow codes that employ different phase lagged unsteady approaches. Hydra uses a harmonic storage approach, and the Vane/Blade Interaction (VBI) code uses a direct storage approach. Harmonic storage reduces memory requirements considerably. The predicted stress for four modes at two engine speeds are presented and are compared with rig test strain gauge data to assess and validate the predictive capability of the codes for forced response. Strain gauge data showed the need to consider harmonics higher than the fundamental vane passing frequency for the max power shaft speed and operating at the conditions. Because of this, it was a good case for validation and for comparing the two codes. Overall, it was found that, stress predictions using the Hydra flow code compare better with data. To the best of the authors’ knowledge, this paper is a first in comparing two different phase lagged unsteady approaches, in the context of forced response, to engine rig data for a High-Work Single Stage turbine.

Effect of Temperature Nonuniformity on Heat Transfer in an Unshrouded Transonic HP Turbine: An Experimental and Computational Investigation

2010 ◽  
Author(s):  
Imran Qureshi ◽  
Andy D. Smith ◽  
Kam S. Chana ◽  
Thomas Povey
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Test Facility ◽  
Effect Of Temperature ◽  
Inlet Temperature ◽  
Experimental Measurements ◽  
Turbine Stage ◽  
Cfd Simulations ◽  
Turbine Inlet

Detailed experimental measurements have been performed to understand the effects of turbine inlet temperature distortion (hot-streaks) on the heat transfer and aerodynamic characteristics of a full-scale unshrouded high pressure turbine stage at flow conditions that are representative of those found in a modern gas turbine engine. To investigate hot-streak migration, the experimental measurements are complemented by three-dimensional steady and unsteady CFD simulations of the turbine stage. This paper presents the time-averaged measurements and computational predictions of rotor blade surface and rotor casing heat transfer. Experimental measurements obtained with and without inlet temperature distortion are compared. Time-mean experimental measurements of rotor casing static pressure are also presented. CFD simulations have been conducted using the Rolls-Royce code Hydra, and are compared to the experimental results. The test turbine was the unshrouded MT1 turbine, installed in the Turbine Test Facility (previously called Isentropic Light Piston Facility) at QinetiQ, Farnborough UK. This is a short duration transonic facility, which simulates engine representative M, Re, Tu, N/T and Tg /Tw at the turbine inlet. The facility has recently been upgraded to incorporate an advanced second-generation temperature distortion generator, capable of simulating well-defined, aggressive temperature distortion both in the radial and circumferential directions, at the turbine inlet.

scholarly journals Optimal and Perfectly Parallel Algorithms for On-demand Data-Flow Analysis

2020 ◽  
pp. 112-140 ◽  
Author(s):  
Krishnendu Chatterjee ◽  
Amir Kafshdar Goharshady ◽  
Rasmus Ibsen-Jensen ◽  
Andreas Pavlogiannis
Keyword(s):  
Data Flow ◽  
Flow Analysis ◽  
Demand Analysis ◽  
Finite Domain ◽  
Data Flow Analysis ◽  
On Demand ◽  
Time Optimal ◽  
Speed Up ◽  
Flow Functions ◽  
Flow Graphs

AbstractInterprocedural data-flow analyses form an expressive and useful paradigm of numerous static analysis applications, such as live variables analysis, alias analysis and null pointers analysis. The most widely-used framework for interprocedural data-flow analysis is IFDS, which encompasses distributive data-flow functions over a finite domain. On-demand data-flow analyses restrict the focus of the analysis on specific program locations and data facts. This setting provides a natural split between (i) an offline (or preprocessing) phase, where the program is partially analyzed and analysis summaries are created, and (ii) an online (or query) phase, where analysis queries arrive on demand and the summaries are used to speed up answering queries.In this work, we consider on-demand IFDS analyses where the queries concern program locations of the same procedure (aka same-context queries). We exploit the fact that flow graphs of programs have low treewidth to develop faster algorithms that are space and time optimal for many common data-flow analyses, in both the preprocessing and the query phase. We also use treewidth to develop query solutions that are embarrassingly parallelizable, i.e. the total work for answering each query is split to a number of threads such that each thread performs only a constant amount of work. Finally, we implement a static analyzer based on our algorithms, and perform a series of on-demand analysis experiments on standard benchmarks. Our experimental results show a drastic speed-up of the queries after only a lightweight preprocessing phase, which significantly outperforms existing techniques.

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