Numerical Simulation of the Flow Field Around Supersonic Air-Intakes

1994 ◽  
Vol 116 (1) ◽  
pp. 116-123 ◽  
Author(s):  
G. Freskos ◽  
O. Penanhoat
Keyword(s):  
Flow Field ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Complex Flow ◽  
Grid Approach ◽  
Entire Flow ◽  
Flow Configurations ◽  
Cost Efficient

The demand for efficiency in today’s and in future civil aircraft is such that experimental studies alone do not suffice to optimize aircraft aerodynamics. In this context, much effort has been spent in the past decade to develop numerical methods capable of reproducing the phenomena that occur in the engine flow field. This paper presents some studies in Computational Fluid Dynamics related to supersonic inlets. Two approaches are considered. First, there is a need for a code capable of calculating in a cost-efficient way the entire flow field around a two-dimensional or three-dimensional inlet, e.g., to perform parametric studies. To this effect, a computing method based on grid construction by mesh generator dedicated to inlet shapes and on the discretization of the unsteady Euler equations with an explicit upwind scheme was developed. The treatment of complex geometries led us to adopt a multiblock grid approach. Therefore particular attention was paid to the treatment of the boundary conditions between the different domains. Second, there is a need for a code that can capture local phenomena in order to get a better understanding of inlet behavior (shock/shock, shock/boundary layer interactions, etc.). To this effect a two-dimensional turbulent Navier-Stokes code is used. The two-equation k-ε turbulence model included in the program seems to be one of the most successful models for calculating flow realistically. Correction of the near-wall influence extends its capability to complex flow configurations, e.g., those with separated zones.

scholarly journals Numerical Simulation of the Flow Field Around Supersonic Air-Intakes

1992 ◽  
Author(s):  
G. Freskos ◽  
O. Penanhoat
Keyword(s):  
Flow Field ◽  
Experimental Studies ◽  
Navier Stokes ◽  
Complex Flow ◽  
Grid Approach ◽  
Parametric Studies ◽  
Entire Flow ◽  
Flow Configurations ◽  
Cost Efficient ◽  
Aircraft Aerodynamics

The demand for efficiency in today’s and in future civil aircraft is such that experimental studies alone do not suffice to optimize aircraft aerodynamics. In this context, much effort has been spent in the past decade to develop numerical methods capable of reproducing the phenomena that occur in the engine flow field. This paper presents some studies in Computational Fluid Dynamics related to supersonic inlets. Two approaches are considered. First, there is a need for code capable of calculating in a cost-efficient way the entire flow field around a 2D or 3D inlet, e.g. to perform parametric studies. To this effect, a computing method based on grid construction by mesh generator dedicated to inlet shapes and on the discretization of the unsteady Euler equations with an explicit upwind scheme was developed. The treatment of complex geometries led us to adopt a multiblock grid approach. Therefore particular attention was paid to the treatment of the boundary conditions between the different domains. Secondly, there is a need for code that can capture local phenomena in order to get a better understanding of inlet behaviour (shock/shock, shock/boundary layer interactions, etc.). To this effect a 2D turbulent Navier-Stokes code is used. The 2 equations k-ε turbulence model included in the program seems to be one of the most successful models for calculating flow realistically. Correction of the near-wall influence extends its capability to complex flow configurations, e.g. those with separated zones.

Experimental and Numerical Investigation of Stator Exit Flow Field of an Automotive Torque Converter

1996 ◽  
Vol 118 (4) ◽  
pp. 835-843 ◽  
Author(s):  
B. V. Marathe ◽  
B. Lakshminarayana ◽  
Y. Dong
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Numerical Investigation ◽  
Three Dimensional ◽  
Axial Flow ◽  
Torque Converter ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Complex Flow ◽  
Rate Of Decay

The objective of this investigation is to understand the nature of the complex flow field inside each element of the torque converter through a systematic experimental and numerical investigation of the flow field. A miniature five-hole probe was used to acquire the data at the exit of the stator at several operating conditions. The flow field is found to be highly three dimensional with substantial flow deviations, and secondary flow at the exit of the stator. The secondary flow structure, caused by the upstream radial variation of the through flow, induces flow overturning near the core. Flow separation near the shell causes flow underturning in this region. The rate of decay of stator wake is found to be slower than that observed in the wakes of axial flow turbine nozzles. The flow predictions by a Navier–Stokes code are in good agreement with the pressure and the flow field measured at the exit of the stator at the design and the off-design conditions.

Experimental Investigation of a Generic Compressor Bleed System

2006 ◽  
Author(s):  
Reinaldo A. Gomes ◽  
Carsten Schwarz ◽  
Michael Pfitzner
Keyword(s):  
Flow Field ◽  
Annular Flow ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Complex Flow ◽  
Pressure Losses ◽  
Aero Engines

Extensive experimental studies on axial compressor bleed-flow systems have been carried out on a three dimensional model of a generic bleed-flow configuration typical for aero engines. The compressor flow is modeled as a clean annular flow. One row of stator vanes is used to impart a constant swirl upstream of the bleed system. The rig is designed modularly in order to allow for inexpensive changes in all of its components and therefore to enlarge the variability of the model. The research is focused onto the generation of an experimental data base, which can be used to derive correlations for the calculation of effective areas and pressure losses. Those data are gained using steady pneumatic measurement technique. In addition, the highly complex flow field in the manifold, which has an important effect onto the bleed-flow, is analyzed using Doppler-Global-Velocimetry (DGV). These measurements were conducted in collaboration with DLR Cologne, who have developed the DGV technique. In this paper the flow field in the manifold is analyzed in detail for two different configurations featuring two and four bleed ducts, respectively. Furthermore the use of a flush design of the slot is compared with a lip design. These data are compared to results from the literature achieved using 2-dimensional configurations.

Numerical Prediction of Wakes in Cascades and Compressor Rotors Including the Effects of Mixing: Part I — Cascade Wakes Including the Effects of Incidence and Freestream Turbulence

1991 ◽  
Author(s):  
N. Suryavamshi ◽  
B. Lakshminarayana
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Freestream Turbulence ◽  
Compressor Cascade ◽  
Pressure Loss Coefficient ◽  
Viscous Losses ◽  
Rate Of Decay ◽  
Entire Flow ◽  
High Reynolds

The results of a numerical investigation to predict the flow in the wake regions of compressor cascades, and wakes and mixing in rotors are presented in this paper. Part I deals with flow in compressor cascades including the effects of change in loading (incidence) and the inlet freestream turbulence intensity. Part II of the paper deals with the predictions of the rotor flow field, including wakes and spanwise mixing. The wake behaviour has been studied numerically using a three-dimensional incompressible Navier-Stokes solver with a high Reynolds number form of the k–ε turbulence model. The equations are solved using a time dependent implicit technique. The agreement between the measured data and predictions is good; including the wake profile, decay, and losses. The ability of the pseudo-compressibility scheme to predict the entire flow field including the wake profile and its decay characteristics, effect of loading and the viscous losses of a compressor cascade is demonstrated. The numerical analysis shows a slight increase in the total pressure loss coefficient through the cascade with increasing turbulence levels. The results also show a slight increase in the rate of decay of the wake at higher turbulence levels but the change in the spreading of the wake was found to be very small with increased turbulence levels.

scholarly journals Numerical Prediction of Wakes in Cascades and Compressor Rotors Including the Effects of Mixing: Part II — Rotor Passage Flow and Wakes Including the Effects of Spanwise Mixing

1991 ◽  
Author(s):  
N. Suryavamshi ◽  
B. Lakshminarayana
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Axial Flow ◽  
Radial Component ◽  
Navier Stokes ◽  
Mean Velocity ◽  
Compressor Rotor ◽  
Entire Flow ◽  
High Reynolds ◽  
Flow Compressor

The results of a numerical investigation to predict the flow field including wakes and mixing in axial flow compressor rotors has been presented in this paper. The wake behaviour in a moderately loaded compressor rotor has been studied numerically using a three-dimensional incompressible Navier-Stokes solver with a high Reynolds number form of the k–ε turbulence model. The equations are solved using a time dependent implicit technique. The agreement between the measured data and the predictions are good; including the blade boundary layer profiles, wake mean velocity profiles and decay. The ability of the pseudo-compressibility scheme to predict the entire flow field including the near and far wake profiles and its decay characteristics, effect of loading and the viscous losses of a three-dimensional rotor flow field has been demonstrated. An analysis of the passage averaged velocities and the pressure coefficients shows that the mixing in the downstream regions away from the hub and annulus walls is dominated by wake diffusion. In regions away from the walls, the radial mixing is predominantly caused by the transport of mass, momentum and energy by the radial component of velocity in the wake.

Numerical Prediction of Wakes in Cascades and Compressor Rotors Including the Effects of Mixing: Part II—Rotor Passage Flow and Wakes Including the Effects of Spanwise Mixing

1992 ◽  
Vol 114 (3) ◽  
pp. 617-626 ◽  
Author(s):  
N. Suryavamshi ◽  
B. Lakshminarayana
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Axial Flow ◽  
Radial Component ◽  
Navier Stokes ◽  
Mean Velocity ◽  
Compressor Rotor ◽  
Entire Flow ◽  
High Reynolds ◽  
Flow Compressor

The results of a numerical investigation to predict the flow field including wakes and mixing in axial flow compressor rotors has been presented in this paper. The wake behavior in a moderately loaded compressor rotor has been studied numerically using a three-dimensional incompressible Navier–Stokes solver with a high Reynolds number form of the k–ε turbulence model. The equations are solved using a time-dependent implicit technique. The agreement between the measured data and the predictions is good, including the blade boundary layer profiles, wake mean velocity profiles, and decay. The ability of the pseudocompressibility scheme to predict the entire flow field including the near and far wake profiles and its decay characteristics, effect of loading, and the viscous losses of a three-dimensional rotor flow field has been demonstrated. An analysis of the passage-averaged velocities and the pressure coefficients shows that the mixing in the downstream regions away from the hub and annulus walls is dominated by wake diffusion. In regions away from the walls, the radial mixing is predominantly caused by the transport of mass, momentum, and energy by the radial component of velocity in the wake.

Large Eddy Simulation of Film Cooling Flow From an Inclined Cylindrical Jet

2003 ◽  
Author(s):  
Sumanta Acharya ◽  
Mayank Tyagi
Keyword(s):  
Flow Field ◽  
Film Cooling ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Wake Region ◽  
Complex Flow ◽  
Mixing Processes ◽  
Hairpin Vortices ◽  
Flow Measurements ◽  
Large Eddy

Predictions of turbine blade film cooling have traditionally employed Reynolds averaged Navier Stokes (RANS) solvers and two-equation models for turbulence. Evaluation of several versions of such models have revealed that the existing two equation models fail to resolve the anisotropy and the dynamics of the highly complex flow field created by the jet-crossflow interaction. A more accurate prediction of the flow field can be obtained from large eddy simulations (LES) where the dynamics of the larger scales in the flow are directly resolved. In the present paper, such an approach has been used, and results are presented for a row of inclined cylindrical holes at blowing ratios of 0.5 and 1, and a Reynolds number of 11100 and 22200 respectively based on the jet velocity and hole diameter. Comparison of the time-averaged LES predictions with the flow measurements of Lavrich and Chiappetta [1] shows that LES is able to predict the flow field with reasonable accuracy. The unsteady three-dimensional flow field is shown to be dominated by packets of hairpin shaped vortices. The dynamics of the hairpin vortices in the wake region of the injected jet and their influence on the unsteady wall heat transfer is presented. Generation of “hot spots” and their migration on the film-cooled surface is associated with the entrainment induced by the hairpin structures. Several geometric properties of a “mixing interface” around hairpin coherent structures are presented to illustrate and quantify their impact on the entrainment rates and mixing processes in the wake region.

Experimental and Numerical Investigation of Stator Exit Flow Field of an Automotive Torque Converter

1994 ◽  
Author(s):  
B. V. Marathe ◽  
B. Lakshminarayana ◽  
Y. Dong
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Numerical Investigation ◽  
Three Dimensional ◽  
Axial Flow ◽  
Torque Converter ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Complex Flow ◽  
Rate Of Decay

The objective of this investigation is to understand the nature of the complex flow field inside each element of the torque converter through a systematic experimental and numerical investigation of the flow field. A miniature five-hole probe was used to acquire the data at the exit of the stat or at several operating conditions. The flow field is found to be highly three-dimensional with substantial flow deviations, and secondary flow at the exit of the stator. The secondary flow structure, caused by the upstream radial variation of the through flow, induces flow overturning near the core. Flow separation near the shell causes flow underturning in this region. The rate of decay of stator wake is found to be slower than that observed in the wakes of axial flow turbine nozzles. The flow predictions by a Navier-Stokes code are in good agreement with the pressure and the flow field measured at the exit of the stator at the design and the off-design conditions.

Numerical Prediction of Wakes in Cascades and Compressor Rotors Including the Effects of Mixing: Part I—Cascade Wakes Including the Effects of Incidence and Free-Stream Turbulence

1992 ◽  
Vol 114 (3) ◽  
pp. 607-616 ◽  
Author(s):  
N. Suryavamshi ◽  
B. Lakshminarayana
Keyword(s):  
Flow Field ◽  
Free Stream ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Compressor Cascade ◽  
Free Stream Turbulence ◽  
Pressure Loss Coefficient ◽  
Viscous Losses ◽  
Entire Flow ◽  
High Reynolds

The results of a numerical investigation to predict the flow in the wake regions of compressor cascades, and wakes and mixing in rotors are presented in this paper. Part I deals with flow in compressor cascades including the effects of change in loading (incidence) and the inlet free-stream turbulence intensity. Part II of the paper deals with the predictions of the rotor flow field, including wakes and spanwise mixing. The wake behavior has been studied numerically using a three-dimensional incompressible Navier–Stokes solver with a high Reynolds number form of the k–ε turbulence model. The equations are solved using a time-dependent implicit technique. The agreement between the measured data and predictions is good, including the wake profile, decay, and losses. The ability of the pseudocompressibility scheme to predict the entire flow field including the wake profile and its decay characteristics, effect of loading, and the viscous losses of a compressor cascade is demonstrated. The numerical analysis shows a slight increase in the total pressure loss coefficient through the cascade with increasing turbulence levels. The results also show a slight increase in the rate of decay of the wake at higher turbulence levels but the change in the spreading of the wake was found to be very small with increased turbulence levels.

Validation of a Navier-Stokes Solver for CFD Computations of Transonic Compressors

2006 ◽  
Author(s):  
Roberto Biollo ◽  
Ernesto Benini
Keyword(s):  
Numerical Model ◽  
Flow Field ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Navier Stokes ◽  
Test Case ◽  
Complex Flow

The progress of numerical methods and computing facilities has led to using Computational Fluid Dynamics (CFD) as a current tool for designing components of gas turbine engines. It is known, however, that a sophisticated numerical model is required to well reproduce the many complex flow phenomena which characterize compression systems, such as shock waves and their interactions with boundary layers and tip clearance flows. In this work, the flow field inside the NASA Rotor 37, a well known test case representative of complex three-dimensional viscous flow structures in transonic bladings, was simulated using a commercial CFD code based on the 3-D Reynolds-averaged Navier-Stokes equations. In order to improve the accuracy of predictions, different aspects of the numerical model were analyzed; in particular, an attempt was made to understand the influence of grid topology, number of nodes and their distribution, turbulence model, and discretization scheme of numerical solution on the accuracy of computed results. Existing experimental data were used to assess the quality of the solutions. The obtainment of a good agreement between computed and measured performance maps and downstream profiles was clearly shown. Also, detailed comparisons with experimental results indicated that the overall features of the three-dimensional shock structure, the shock-boundary layer interaction, and the wake development can be calculated very well in the numerical approach for all the operating conditions. The possibility for a numerical model to better understand the aerodynamic behaviour of existing transonic compressors and to help the design of new configurations was demonstrated. It was also pointed out that the development of an accurate model requires the knowledge of both the physical phenomena place within the flow field and the features of the code which model them.

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