Isothermal Boundary Condition at Casing Applied to the Rotor 37 Transonic Axial Flow Compressor

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Dario Bruna ◽  
Mark G. Turner
Keyword(s):  
Boundary Condition ◽  
Axial Flow ◽  
Low Flow ◽  
Cfd Simulations ◽  
Data Set ◽  
Isothermal Boundary ◽  
Flow Test ◽  
Total Temperature ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Compressor

Computational fluid dynamics (CFD) simulations are presented with an isothermal boundary condition at the casing for running NASA Rotor 37. The casing temperature is set to the inlet total temperature. Relative to the adiabatic simulations, the comparison to experimental efficiency is much improved for the 100% speed line. The efficiency difference between the isothermal and adiabatic solutions is about 1%, and matches the low-flow test condition. The profiles of total temperature with the isothermal boundary condition match the data near the casing. The adiabatic simulation has a total temperature overshoot that has been consistently part of any data comparison of CFD with this data set, and is typical of most compressor calculations. The efficiency profile has a similar improvement in matching the data because of its relationship to temperature. The real rig is not isothermal at the casing and may require more complex simulations such as a conjugate heat transfer approach to truly match the physics. However, the isothermal boundary condition is more accurate and more realistic than the adiabatic boundary condition.

A Rothalpy Analysis for the Isothermal Boundary Condition at Casing Applied to the Rotor 37 Transonic Axial Flow Compressor

2013 ◽  
Author(s):  
Dario Bruna ◽  
Mark G. Turner
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Axial Compressor ◽  
Axial Flow ◽  
Low Flow ◽  
Isothermal Boundary ◽  
Flow Test ◽  
Total Temperature ◽  
Flow Compressor ◽  
Set Up

CFD simulations have been set-up with an isothermal boundary condition at the casing for running the NASA Rotor 37 axial compressor. The casing temperature was set to the inlet total temperature. The comparison to data was much improved for the efficiency for the 100% speed line relative to the adiabatic simulations. The efficiency difference between the isothermal and adiabatic solutions is about 1%, with the isothermal calculation matching the low flow test condition. The profiles of total temperature with the isothermal boundary condition matched the data near the casing without any overshoot, typical of most compressor calculations. Also the efficiency profile had a similar improvement in matching the data because of its relationship to temperature. A similar comparison between isothermal and adiabatic cases has been carried out for the same geometry with double the design clearance. The working range based on the steady CFD calculations is about half that of the design clearance case which is felt to be realistic. Moreover a detailed analysis based on conservation of Rothalpy has been made and applied to the rotor. Mass averaged Rothalpy is not conserved due to a frictional power term associated with the stationary case as well as heat transfer. The effects of these terms show the extent of the heat transfer is between 10–20% of span away from the casing. The heat transfer effect calculated with the isothermal boundary condition simulation is thought to be real, and accounting for it matches data better than using an adiabatic assumption. However, the real rig would probably not be isothermal at the casing and may require more complex simulations such as a conjugate heat transfer approach.

Aspirating Probe Measurements of the Unsteady Total Temperature Field Downstream of an Embedded Stator in a Multistage Axial Flow Compressor

1996 ◽  
Author(s):  
N. Suryavamshi ◽  
B. Lakshminarayana ◽  
J. Prato
Keyword(s):  
Axial Flow ◽  
Pressure Data ◽  
Peak Efficiency ◽  
Axial Flow Compressor ◽  
Composite Flow ◽  
Total Temperature ◽  
Temperature And Pressure ◽  
Flow Compressor ◽  
Isentropic Efficiency ◽  
Probe Measurements

The results from the area traverse measurements of the unsteady total temperature using a high response aspirating probe downstream of the second stator of a three stage axial flow compressor are presented. The measurements were conducted at the peak efficiency operating point. The unsteady total temperature data is resolved into deterministic and unresolved components. Hub and casing regions have high levels of unsteadiness and consequently high levels of mixing. These regions have significant levels of shaft resolved and unresolved unsteadiness. Comparisons are made between the total temperature and the total pressure data to examine the rotor 2 wake characteristics and the temporal variation of the stator exit flow. Isentropic efficiency calculations at the midpitch location show that there is about a 4% change in the algebraically averaged efficiency across the blades of the second rotor and if all the rotor 2 blades were behaving as a “best” blade, the improvement in efficiency would be about 1.3%. An attempt is made to create a composite flow field picture by correlating the unsteady velocity data with temperature and pressure data.

On the Use of Atmospheric Boundary Conditions for Axial-Flow Compressor Stall Simulations

2004 ◽  
Vol 127 (2) ◽  
pp. 349-351 ◽  
Author(s):  
M. Vahdati ◽  
A. I. Sayma ◽  
C. Freeman ◽  
M. Imregun
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Boundary Conditions ◽  
Hysteresis Loop ◽  
Axial Flow ◽  
Computational Domain ◽  
Computational Fluid Dynamics Cfd ◽  
Fan Blade ◽  
Flow Compressor ◽  
Speed Characteristic

This paper describes a novel way of prescribing computational fluid dynamics (CFD) boundary conditions for axial-flow compressors. The approach is based on extending the standard single passage computational domain by adding an intake upstream and a variable nozzle downstream. Such a route allows us to consider any point on a given speed characteristic by simply modifying the nozzle area, the actual boundary conditions being set to atmospheric ones in all cases. Using a fan blade, it is shown that the method not only allows going past the stall point but also captures the typical hysteresis loop behavior of compressors.

Numerical Investigation of Tandem Airfoils for Subsonic Axial-Flow Compressor Blades

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Jonathan McGlumphy ◽  
Wing-Fai Ng ◽  
Steven R. Wellborn ◽  
Severin Kempf
Keyword(s):  
Axial Flow ◽  
Computational Approach ◽  
Compressor Blade ◽  
Large Scatter ◽  
Compressor Blades ◽  
Cascade Flow ◽  
Computational Fluid Dynamics Cfd ◽  
Overall Performance ◽  
Flow Compressor

The tandem airfoil has potential to do more work as a compressor blade than a single airfoil without incurring significantly higher losses. Although tandem blades are sometimes employed as stators, they have not been used in any known commercial rotors. While the long-term goal for this program is development of a commercially viable tandem rotor, this paper discusses tandem airfoils in subsonic, shock-free rectilinear cascade flow. Existing literature data on tandem airfoils in rectilinear cascades have been compiled and presented in a Lieblein loss versus loading correlation. Large scatter in the data gave motivation to conduct an extensive 2D computational fluid dynamics (CFD) study evaluating the overall performance as a function of the relative positions of the forward and aft airfoils. CFD results were consistent with trends in the open literature, both of which indicate that a properly designed tandem airfoil can outperform a comparable single airfoil on and off design. The general agreement of the CFD and literature data serves as a validation for the computational approach.

scholarly journals A Loss and Deflection Model for Compressor Blading at High Negative Incidence

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Luis E. Ferrer-Vidal ◽  
Marc Schneider ◽  
Alessandro Allegretti ◽  
Vassilios Pachidis
Keyword(s):  
Performance Prediction ◽  
Axial Flow ◽  
Numerical Approach ◽  
Turning Angle ◽  
Blade Cascade ◽  
Through Flow ◽  
Computational Fluid Dynamics Cfd ◽  
Aerodynamic Parameters ◽  
Flow Compressor ◽  
Performance Estimates

AbstractWhile significant advances have come about for turbomachinery off-design performance characterization using computational fluid dynamics (CFD), the need for quick performance estimates at challenging off-design conditions still requires the use of lower-order models, such as mean-line analyses and through-flow tools. These inviscid tools require blade performance correlations formulated in terms of loss and turning angle as a function of blade geometric and aerodynamic parameters. Traditionally, such correlations have relied on the empirical data from blade cascade tests at nominal incidence conditions. This limitation on the applicability of the blade correlations has caused performance modeling of the sub-idle regime to be off-limits to this type of correlation-based approaches. This paper addresses the development of blade loss and deviation models applicable to the sub-idle regime using a parametric numerical approach. 2D CFD results are used to generate a model that is then applied to mean-line and through-flow analyses aimed at predicting the sub-idle map of an axial flow compressor. The model proves to be a valuable tool for quick sub-idle performance estimates and allows existing correlation-based performance prediction methods to be extended into the sub-idle regime.

scholarly journals Experimental Investigation of the Flow Field in a Multistage Axial Flow Compressor

1996 ◽  
Vol 2 (4) ◽  
pp. 247-258 ◽  
Author(s):  
B. Lakshminarayana ◽  
N. Suryavamshi ◽  
J. Prato ◽  
R. Moritz
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Axial Flow ◽  
Suction Side ◽  
Mean Velocity ◽  
Axial Flow Compressor ◽  
Total Temperature ◽  
Single Sensor ◽  
Flow Compressor ◽  
Thermocouple Probe

The nature of the flow field in a three stage axial flow compressor, including a detailed survey at the exit of an embedded stator as well as the overall performance of the compressor is presented and interpreted in this paper. The measurements include area traverse of a miniature five hole probe (1.07 mm dia) downstream of stator 2, radial traverses of a miniature five hole probe at the inlet, downstream of stator 3 and at the exit of the compressor at various circumferential locations, area traverse of a low response thermocouple probe downstream of stator 2, radial traverses of a single sensor hot-wire probe at the inlet, and casing static pressure measurements at various circumferential and axial locations across the compressor at the peak efficiency operating point. Mean velocity, pressure and total temperature contours as well as secondary flow contours at the exit of the stator 2 are reported and interpreted. Secondary flow contours show the migration of fluid particles toward the core of the low pressure regions located near the suction side casing endwall corner.

Pressure Fluctuation on Casing Wall of Isolated Axial Compressor Rotors at Low Flow Rate

1993 ◽  
Vol 115 (1) ◽  
pp. 19-26 ◽  
Author(s):  
M. Inoue ◽  
M. Kuroumaru ◽  
Y. Ando
Keyword(s):  
Flow Rate ◽  
Pressure Fluctuation ◽  
Correlation Functions ◽  
Pressure Fluctuations ◽  
Axial Compressor ◽  
Axial Flow ◽  
Tip Clearance ◽  
Low Flow ◽  
Flow Compressor ◽  
Low Flow Rate

The pressure fluctuations on the casing wall of two axial flow compressor rotors with various tip clearances have been analyzed by the use of two kinds of correlation functions. The behavior of the pressure fluctuation varies depending on tip clearance and blade solidity. In the case of small tip clearance, the nature of disturbances becomes random as the flow rate is reduced to a stall condition. For moderate tip clearance, coherent-structured disturbances appear intermittently at low flow rate. They appear more frequently as the solidity is increased and the flow rate becomes lower. For large tip clearance, the coherent structured disturbances exist even at considerably higher flow rates. Corresponding to these features, there are peculiar patterns in the correlation designated as “phase-locked correlation functions.”

Large-Scale DES Analysis of Unsteady Flow Field in a Multi-Stage Axial Flow Compressor at Off-Design Condition Using K Computer

2015 ◽  
Author(s):  
Kazutoyo Yamada ◽  
Masato Furukawa ◽  
Satoshi Nakakido ◽  
Akinori Matsuoka ◽  
Kentaro Nakayama
Keyword(s):  
Boundary Condition ◽  
Unsteady Flow ◽  
Gas Turbines ◽  
Large Scale ◽  
Axial Flow ◽  
Axial Flow Compressor ◽  
Eddy Simulation ◽  
Multi Stage ◽  
Flow Phenomena ◽  
Flow Compressor

The paper presents the results of large-scale numerical simulations which were conducted for better understanding of unsteady flow phenomena in a multi-stage axial flow compressor at off-design condition. The compressor is a test rig compressor which was used for development of the industrial gas turbine, Kawasaki L30A. The compressor consists of 14 stages, the front two stages and the front half stages of which were investigated in the present study. The final goal of this study is to elucidate the flow mechanism of the rotating stall inception in the multi-stage axial compressor for actual gas turbines, and according to the test data it is considered that the 2nd stage and the 5th or 6th stage are suspected of leading to the stall. In order to capture precise flow physics in the compressor, a computational mesh for the simulation was generated to have at least several million cells per passage, which amounted to 650 million cells for the front 2-stage simulation and two billion cells for the front 7-stage simulation (about three hundred million cells for each stage). Since these were still not enough for the large-eddy simulation (LES), the detached-eddy simulation (DES) was employed, which can calculate flow fields except near-wall region by LES. The required computational resources were quite large for such simulations, so the computations were conducted on the K computer (RIKEN AICS in Japan). The simulations were well validated, showing good agreement with the measurement results obtained in the test. In the validation, the effect of the boundary condition for the casing wall was also investigated by comparing the results between the adiabatic boundary condition and the isothermal boundary condition. As for the unsteady effect, the wake/blade interaction was investigated in detail. In addition, unsteady flow phenomena in the present compressor at off-design condition were analyzed by using data mining techniques such as vortex identification and limiting streamline drawing with the LIC (line integral convolution) method. The simulation showed that they could be caused by the corner separation on the hub side.

Axial-Flow Compressor Model Based on a Cascade Stacking Technique and Neural Networks

2002 ◽  
Author(s):  
Ernesto Benini ◽  
Andrea Toffolo
Keyword(s):  
Neural Networks ◽  
Three Dimensional ◽  
Axial Flow ◽  
Design Tool ◽  
Preliminary Design ◽  
Cfd Simulations ◽  
Axial Flow Compressor ◽  
Multi Stage ◽  
Stator Vane ◽  
Flow Compressor

This paper introduces a cascade-stacking technique for the development of a gas turbine multi-stage axial-flow compressor model. A large database of stationary and rotating cascade performance is first obtained by quasi three-dimensional CFD simulations and used to train neural networks for the prediction of cascade performance under generalized conditions. Then the model directly calculates the operating point of a compressor having known geometry characteristics, including variable inlet guide/stator vane effects, as a function of mass flow rate and rotational speed. The model can also be used as a valuable preliminary design tool, obtaining geometry characteristics by imposing flow patterns.

Analysis of Turbofan Performance Under Total Pressure Distortion at Various Operating Points

2015 ◽  
Author(s):  
David B. Weston ◽  
Steven E. Gorrell ◽  
Matthew L. Marshall ◽  
Carol V. Wallis
Keyword(s):  
Total Pressure ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Cfd Simulations ◽  
Blade Loading ◽  
Distortion Analysis ◽  
Work Input ◽  
Total Temperature ◽  
Computational Fluid Dynamics Cfd ◽  
Operating Points

Inlet distortion is an important consideration in fan performance. The focus of this paper is a series of high-fidelity time accurate Computational Fluid Dynamics (CFD) simulations of a multistage fan at choke, design, and near stall operating conditions. These investigate distortion transfer and generation as well as the underlying flow physics of these phenomena under different operating conditions. The simulations are performed on the full annulus of a 3 stage fan and are analyzed. The code used to carry out these simulations is a modified version of OVERFLOW 2.2. The inlet is specified as a 1/rev total pressure distortion. Analysis includes the phase and amplitude of total temperature and pressure distortion through each stage of the fan and blade loading. The total pressure distortion does not change in severity through the fan, but the peak pressure distortion rotates by as much as 45° at the near stall point. This is due to a variation in the work input around the blades of the rotor. This variation is also responsible for the generation of total temperature distortion in the fan. The rotation of the total temperature distortion becomes more pronounced as the fan approaches stall, and the total temperature distortion levels increase. The amount of work performed by a single blade can vary by as much as 25% in the first stage at near stall. The variation in work becomes more pronounced as the fan approaches stall. The passage shock in the rotor blades moves nearly 20% of the blade chord in both the peak efficiency and near stall cases.

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