scholarly journals Interstage Pressures of a Multistage Compressor with Intercooling

Entropy ◽  
2021 ◽  
Vol 23 (3) ◽  
pp. 351
Author(s):  
Helen Lugo-Méndez ◽  
Teresa Lopez-Arenas ◽  
Alejandro Torres-Aldaco ◽  
Edgar Vicente Torres-González ◽  
Mauricio Sales-Cruz ◽  
...  
Keyword(s):  
Pressure Drops ◽  
Analytical Expression ◽  
Compression Stage ◽  
Multistage Compressors ◽  
Multistage Compressor ◽  
Gas Properties

This paper considers the criterion of minimum compression work to derive an expression for the interstage pressure of a multistage compressor with intercooling that includes the gas properties, pressure drops in the intercoolers, different suction gas temperatures, and isentropic efficiencies in each compression stage. The analytical expression for the interstage pressures is applied to estimate the number of compression stages and to evaluate its applicability in order to estimate interstage pressures in the operation of multistage compressors, which can be especially useful when their measurements are not available.

scholarly journals Aerodynamic Modeling of Multistage Compressor Flowfields: Part 2 — Modeling Deterministic Stresses

1997 ◽  
Author(s):  
Edward J. Hall
Keyword(s):  
Test Data ◽  
Axial Flow ◽  
Time Dependent ◽  
State University ◽  
Turbine Engine ◽  
Prediction Scheme ◽  
Proposed Model ◽  
Multistage Compressors ◽  
Multistage Compressor ◽  
Flow Compressor

The primary purpose of this study was to investigate improved numerical techniques for predicting flows through multistage compressors. The vehicle chosen for this study was the Pennsylvania State University Research Compressor (PSRC). The PSRC facility consists of a 3-1/2 stage axial flow compressor which shares design features which are consistent with embedded stages of modern gas turbine engine axial flow compressors. In Part 2 of this two part paper, time-dependent predictions of rotor/stator/rotor aerodynamic interactions were employed to quantify the levels and distribution of deterministic stresses resulting from the average-passage flowfield description. Details of the spanwise and blade-to-blade distributions of the velocity correlations are examined and compared with results based on physical deterministic flow structures such as blade wakes and clearance flows. The predicted “apparent” wake profile decay resulting from the interaction of the wake through a downstream blade row is presented and compared with test data. This “apparent” wake profile decay is employed to define a simplified model for deterministic stress correlations in a steady state flowfield prediction scheme which retains the “mixing plane” methodology. Calculations based on this proposed model are described and predicted results are compared with both time-dependent predictions and test data. The resulting prediction strategy is both computational efficient and contains sufficient physical realism to permit its use in design studies.

scholarly journals The Investigation of the Stability for Multistage Axial Compressors

1985 ◽  
Author(s):  
Diyi Tang ◽  
Wenlan Li ◽  
Mengzi Cong
Keyword(s):  
Experimental Data ◽  
Physical Model ◽  
Axial Compressors ◽  
Volume Model ◽  
Multistage Compressors ◽  
Multistage Compressor ◽  
The Stability

The “actuator-delay-volume” is used as a physical model for stages of compressors instead of “actuator-lumped volume” model to predict the stability of multistage compressors. The stall line of a multistage compressor is predicted with these two models respectively. The results of simulation are compared with the experimental data of a compressor rig. In order to identify the investigation, the tests, in which the engine is forced into stall and supplied with distorted inflow, have been conducted. The investigation shows that the model is well improved by incorporating an “inertia link” into the model between the “actuator” and the “lumped volume”.

Numerical Study of the Penny Cavity Leakage Effects From Variable Guide Vanes in a High Pressure Compressor: Adjustment of Standard-RANS-CFD-Model to a Hybrid LES Calculation

2019 ◽  
Author(s):  
Hannes Wolf ◽  
Alexander Halcoussis
Keyword(s):  
High Resolution ◽  
Turbulence Model ◽  
Turbulent Mixing ◽  
Flow Structures ◽  
Test Case ◽  
Guide Vanes ◽  
Blade Row ◽  
Multistage Compressors ◽  
Multistage Compressor ◽  
Les Model

Abstract Variable guide vanes are airfoils, normally in the front stages of multistage compressors, that can be restaggered to extend the compressor’s operational range. To allow the variable guide vanes to rotate the design will inevitably include a gap or cavity between the vane’s rotating mounting feature (Penny) and the stationary inner and outer sidewalls. These penny cavities cause additional leakages which impact losses, and airfoil turning, so reducing a compressor’s efficiency and stability. A compressor model which accurately simulates the penny cavity leakage is central to improving the design. This paper presents a study looking into how to accurately include penny cavity leakage effects during the design of multistage compressors. Multiple blade-row RANS-based flow simulations are the current state-of-the-art standard during the design of multistage compressors. However, it is unlikely that such models have the numerical accuracy to simulate the penny cavity leakage effects in detail: firstly the RANS-turbulence model cannot accurately recreate the turbulent mixing which takes place between the leakage and the main flow, and secondly because a typical multiple blade-row mesh is too coarse to resolve the details of the much smaller penny cavity. To compensate for this, the numerical modelling of penny cavities in the design of a compressor would need to be adjusted. On the other hand, a dedicated hybrid LES-model can more accurately simulate the secondary flows with its significant turbulent mixing, at the cost of computational capacity. In this paper, high resolution hybrid LES-simulations have been used as a benchmark to adjust RANS-calculations typical for the design of a multistage compressor. The paper presents the following steps: Using a standard Jet-in-Crossflow test case, a high resolution model was evaluated using both RANS and a hybrid LES model, and compared against measurements. The flow structures were analyzed and compared to measurements of this test case available from literature. These show that the hybrid LES-model performed significantly better than the RANS-model, in being able to predict the jet impact and flow structures. For a second model consisting of a generic compressor variable vane with penny cavity. RANS and hybrid LES simulations were performed with a highly refined mesh in the region of the penny cavity. The modelling is described in detail and the resulting penny cavity effects compared. Finally, the vane with standard mesh and penny cavity was run using RANS-turbulence CFD and compared to the above. From this conclusions were drawn on how to transfer experience from the higher-fidelity turbulence model to a more industry-standard RANS model, which could for instance be used during the design phase of a multistage compressor.

scholarly journals Observations on Rotating Instabilities and Spike Type Stall Inception in a High-Speed Multistage Compressor

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Johannes Schreiber ◽  
Benoit Paoletti ◽  
Xavier Ottavy
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Stall Inception ◽  
Time Period ◽  
Type Flow ◽  
Different Types ◽  
Multistage Compressors ◽  
Multistage Compressor ◽  
Field Modulation ◽  
Rotating Instability

This work investigates high-frequency measurements for the contribution to the understanding of different stall inception types in high-speed multistage compressors. A 3.5-stage high-speed axial multistage compressor is investigated with a 2 MW test rig in the Laboratoire de Mécanique des Fluides et d’Acoustique (LMFA) at Ecole Centrale de Lyon, France. Two different types of instabilities arise in this compressor as a function of shaft speed. At part speed, a controversy called “rotating instability” type flow field modulation is identified with the measurements. New results are the demonstration of the periodic behavior of this instability and the analogy to classical frequency modulation, periodic to one revolution of the instability. Furthermore, the amplitude of the instability is modulated by the time period of a rotor revolution. At nominal speed, the abrupt spike type stall inception is detected, taking usually less than five rotor revolutions.

Use of Experimental Interstage Performance Data to Obtain Optimum Performance of Multistage Axial Compressors

1962 ◽  
Vol 84 (2) ◽  
pp. 187-194 ◽  
Author(s):  
Laurence E. Brown ◽  
Fred G. Groh
Keyword(s):  
Performance Data ◽  
Focus Attention ◽  
Simple Method ◽  
Axial Compressors ◽  
One Stage ◽  
Performance Map ◽  
Multistage Compressors ◽  
Compressor Performance ◽  
Multistage Compressor ◽  
The Individual

Experimental interstage performance data provide the most useful basis currently available for correction of faults in performance of multistage compressors. However, to describe stage performance adequately requires much more information than the amount needed to describe over-all compressor performance, and to interpret the data requires that all of this information be correlated. Because the wealth of the data may conceal its meaning, some simple method is needed to focus attention on the matching of one stage to another and to the over-all compressor as well. A technique is presented whereby performance of individual stages can be depicted graphically upon the performance map of an over-all multistage compressor. Through this presentation the individual and over-all effects can be examined together. Insight is afforded into performance relationships of one stage to another; and faults can be diagnosed if any exist in the matching, radial or axial, of individual stages. Changes of blade geometry can then be prescribed upon a clear and explicit basis. To illustrate use of the technique, data are presented describing gains that have been achieved experimentally.

On the influence of specimen thickness in TEM images of super-conducting vortices

1996 ◽  
Vol 54 ◽  
pp. 724-725
Author(s):  
J. Bonevich ◽  
D. Capacci ◽  
G. Pozzi ◽  
K. Harada ◽  
H. Kasai ◽  
...  
Keyword(s):  
Flux Line ◽  
Analytical Form ◽  
Realistic Model ◽  
Electron Holography ◽  
Specimen Thickness ◽  
Flux Tubes ◽  
Analytical Expression ◽  
Flux Lines ◽  
Normal Core ◽  
Two Parameters

The successful observation of superconducting flux lines (fluxons) in thin specimens both in conventional and high Tc superconductors by means of Lorentz and electron holography methods has presented several problems concerning the interpretation of the experimental results. The first approach has been to model the fluxon as a bundle of flux tubes perpendicular to the specimen surface (for which the electron optical phase shift has been found in analytical form) with a magnetic flux distribution given by the London model, which corresponds to a flux line having an infinitely small normal core. In addition to being described by an analytical expression, this model has the advantage that a single parameter, the London penetration depth, completely characterizes the superconducting fluxon. The obtained results have shown that the most relevant features of the experimental data are well interpreted by this model. However, Clem has proposed another more realistic model for the fluxon core that removes the unphysical limitation of the infinitely small normal core and has the advantage of being described by an analytical expression depending on two parameters (the coherence length and the London depth).

Contrast From Point Defects in The Infinitesimal Approximation

1980 ◽  
Vol 38 ◽  
pp. 350-351
Author(s):  
L. J. Sykes ◽  
J. J. Hren
Keyword(s):  
Electron Microscope ◽  
Point Defects ◽  
Broad Class ◽  
Stacking Fault ◽  
Crystalline Solids ◽  
Dislocation Loops ◽  
Analytical Expression ◽  
Stacking Fault Tetrahedra

In electron microscope studies of crystalline solids there is a broad class of very small objects which are imaged primarily by strain contrast. Typical examples include: dislocation loops, precipitates, stacking fault tetrahedra and voids. Such objects are very difficult to identify and measure because of the sensitivity of their image to a host of variables and a similarity in their images. A number of attempts have been made to publish contrast rules to help the microscopist sort out certain subclasses of such defects. For example, Ashby and Brown (1963) described semi-quantitative rules to understand small precipitates. Eyre et al. (1979) published a catalog of images for BCC dislocation loops. Katerbau (1976) described an analytical expression to help understand contrast from small defects. There are other publications as well.

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