A Calculation Procedure for Three-Dimensional, Viscous, Compressible Duct Flow. Part II—Stagnation Pressure Losses in a Rectangular Elbow

1979 ◽  
Vol 101 (4) ◽  
pp. 423-428 ◽  
Author(s):  
John Moore ◽  
Joan G. Moore
Keyword(s):  
Three Dimensional ◽  
Inviscid Flow ◽  
Stagnation Pressure ◽  
Calculation Procedure ◽  
Duct Flow ◽  
Pressure Losses ◽  
Pressure Distributions ◽  
Starting Point ◽  
Flow Part ◽  
Good Agreement

Three-dimensional, turbulent flow is calculated in an elbow used by Stanitz for an experimental investigation of secondary flow. Calculated wall-static pressure distributions and distributions of stagnation-pressure loss, both spatial and as a function of mass-flow ratio, are in good agreement with Stanitz’ measurements, justifying the use of a relatively simple mixing-length viscosity model. The calculation procedure and the results of two-dimensional “inviscid” flow calculations used as the starting point for the present calculations are described in Part I of this paper. The computed flow field shows clearly the development of the passage vortices.

Calculations of Three-Dimensional, Viscous Flow and Wake Development in a Centrifugal Impeller

1981 ◽  
Vol 103 (2) ◽  
pp. 367-372 ◽  
Author(s):  
J. Moore ◽  
J. G. Moore
Keyword(s):  
Viscous Flow ◽  
Pressure Field ◽  
Three Dimensional ◽  
Inviscid Flow ◽  
Calculation Procedure ◽  
Wake Flow ◽  
Centrifugal Impeller ◽  
Duct Flow ◽  
Reduced Pressure ◽  
Flow Calculation

A partially-parabolic calculation procedure is used to calculate flow in a centrifugal impeller. This general-geometry, cascade-flow method is an extension of a duct-flow calculation procedure. The three-dimensional pressure field within the impeller is obtained by first performing a three-dimensional inviscid flow calculation and then adding a viscosity model and a viscous-wall boundary condition to allow calculation of the three-dimensional viscous flow. Wake flow, resulting from boundary layer accumulation in an adverse reduced-pressure gradient, causes blockage of the impeller passage and results in significant modifications of the pressure field. Calculated wake development and pressure distributions are compared with measurements.

A Calculation Procedure for Three-Dimensional, Viscous, Compressible Duct Flow. Part I—Inviscid Flow Considerations

1979 ◽  
Vol 101 (4) ◽  
pp. 415-422 ◽  
Author(s):  
John Moore ◽  
Joan G. Moore
Keyword(s):  
Three Dimensional ◽  
Inviscid Flow ◽  
Solution Procedure ◽  
Curvilinear Coordinates ◽  
Two Dimensional ◽  
Duct Flow ◽  
Conservation Equations ◽  
Two Dimensional Flow ◽  
Flow Part ◽  
Orthogonal Curvilinear Coordinates

A method for computing three-dimensional duct flows is described. The procedure involves iteration between a marching integration of the conservation equations through the flow field and the solution of an elliptic pressure-correction equation. The conservation equations are written in orthogonal curvilinear coordinates. The solution procedure is illustrated by calculations of two-dimensional flow in an accelerating rectangular elbow with 90 deg of turning. An approach to calculating three-dimensional viscous flow, starting with the solution for two-dimensional inviscid flow is suggested. This approach is used in Part II which starts with the results of the present two-dimensional “inviscid” flow calculations.

Simulations to Determine Laminar Loss Coefficients for Flow in Circular Ducts With Arbitrary Planar Bifurcation Geometries

2008 ◽  
Author(s):  
Tim A. Handy ◽  
Evan C. Lemley ◽  
Dimitrios V. Papavassiliou ◽  
Henry J. Neeman
Keyword(s):  
Pressure Loss ◽  
Three Dimensional ◽  
Computer Code ◽  
Two Dimensions ◽  
Stagnation Pressure ◽  
Loss Coefficient ◽  
Pressure Losses ◽  
Common Plane ◽  
Loss Coefficients ◽  
Inlet Duct

The goal of this study was to determine laminar stagnation pressure loss coefficients for circular ducts in which flow encounters a planar bifurcation. Flow conditions and pressure losses in these laminar bifurcations are of interest in microfluidic devices, in porous media, and in other networks of small ducts or pores. Until recently, bifurcation geometries had been studied almost exclusively for turbulent flow, which is often found in fluid supply and drain systems. Recently, pressure loss coefficients from simulations of a few arbitrary bifurcation geometries in two-dimensions have been published — the present study describes the extension of these two-dimensional simulations to three-dimensional circular ducts. The pressure loss coefficients determined in this study are intended to allow realistic simulation of existing laminar flow networks or the design of these networks. This study focused on a single inlet duct with two outlet ducts, which were allowed to vary in diameter, flow fraction, and angle — all relative to the inlet duct. All ducts considered in this study were circular with their axes in a common plane. Laminar stagnation pressure loss coefficients were determined by simulating incompressible flow through 475 different geometries and flow condition combinations. In all cases, the flow was laminar in the inlet and outlet ducts with a Reynolds number of 15 in the inlet duct. Simulations of the dividing flow geometries were done using FLUENT and a custom written computer code, which automated the process of creating the three-dimensional flow geometries. The outputs, pressure and velocity distributions at the inlet and outlets, were averaged over the circular ducts and then used to calculate pressure loss coefficients for each of the geometries and flow fraction scenarios simulated. The results for loss coefficient for the geometries considered ranged from 2.0 to 70. The loss coefficient for any geometry increased significantly as the outlet flow fraction increased. A consistent increase in loss coefficient was also observed as a function of decreasing outlet duct diameter. Less significant variation of the loss coefficient was observed as a function of the angles of the outlet ducts.

scholarly journals The Influence of Flow Rate on the Wake in a Centrifugal Impeller

1982 ◽  
Author(s):  
M. W. Johnson ◽  
J. Moore
Keyword(s):  
Flow Rate ◽  
Incidence Angle ◽  
Three Dimensional ◽  
Stagnation Pressure ◽  
Centrifugal Impeller ◽  
Suction Surface ◽  
Cross Sectional ◽  
Flow Rates ◽  
Pressure Losses ◽  
Compressor Impeller

Three-dimensional flows and their influence on the stagnation pressure losses in a centrifugal compressor impeller have been studied. All 3 mutally perpendicular components of relative velocity and stagnation pressure on 5 cross-sectional planes, between the inlet and outlet of a 1 m dia shrouded impeller running at 500 rpm were measured. Comparisons were made between results for a flow rate corresponding to nearly zero incidence angle and two other flows, with increased and reduced flow rates. These detailed measurements show how the position of separation of the shroud boundary layer moved downstream and the wake’s size decreased, as the flow rate was increased. The wake’s location, at the outlet of the impeller, was also observed to move from the suction surface at the lowest flow rate, to the shroud at higher flow rates.

On an Approximate Method of Calculating Pressures on Non-lifting Head Shapes at Supersonic Speeds

1955 ◽  
Vol 6 (1) ◽  
pp. 31-45
Author(s):  
H. K. Zienkiewicz
Keyword(s):  
Method Of Characteristics ◽  
Order Theory ◽  
Stagnation Pressure ◽  
Slender Body Theory ◽  
Pressure Losses ◽  
The Method Of Characteristics ◽  
Curvature Approximation ◽  
Body Theory ◽  
Theory And Experiment ◽  
Good Agreement

SummarySlender-body theory is used to derive the ogive of curvature approximation for very slender, pointed, convex head shapes at supersonic speeds. Results of application of this approximation, together with the λ-method for circular arc ogives, to a variety of non-slender head shapes show very good agreement with the method of characteristics, van Dyke's second-order theory and experiment. Good agreement with the method of characteristics and with experiment is obtained even in cases when the stagnation pressure losses across the nose shock wave are not negligible.

Application of a Two-Dimensional Supersonic Passage Analysis to the Design of Compressor Rotors

1974 ◽  
Author(s):  
R. G. Hantman ◽  
A. A. Mikolajczak ◽  
F. J. Camarata
Keyword(s):  
Leading Edge ◽  
Inviscid Flow ◽  
Two Dimensional ◽  
Compressor Rotor ◽  
Pressure Distributions ◽  
Displacement Thickness ◽  
Blade Section ◽  
Comparison Of The Results ◽  
Rotational Method ◽  
Good Agreement

A description of a two-dimensional supersonic cascade passage analysis and its application to the design of a high hub-to-tip ratio supersonic compressor rotor is presented. The analysis, applicable to the case in which the inviscid flow is everywhere supersonic, includes an entrance region calculation which accounts for blade leading edge bluntness effects, and a passage and wake region calculation. The inviscid part of the analysis is solved using a rotational method of characteristics. The effect of the blade boundary layer displacement thickness is taken into consideration. Comparison of the results of the analysis with supersonic cascade data is made, showing good agreement in overall performance prediction, in blade surface static pressure distributions, and in achievement of the desired shock wave patterns. A comparison of the results of the analysis is made also with the performance of a blade section of a high hub-to-tip ratio supersonic compressor and acceptable agreement obtained.

A wake singularity potential flow model for airfoils experiencing trailing-edge stall

1993 ◽  
Vol 251 ◽  
pp. 203-218 ◽  
Author(s):  
W. W. H. Yeung ◽  
G. V. Parkinson
Keyword(s):  
Potential Flow ◽  
Inviscid Flow ◽  
Near Wake ◽  
Trailing Edge ◽  
Pressure Distributions ◽  
Free Streamlines ◽  
Potential Flow Model ◽  
Theoretical Pressure ◽  
Simple Sequence ◽  
Good Agreement

An incompressible inviscid flow theory for single and two-element airfoils experiencing trailing-edge stall is presented. For the single airfoil the model requires a simple sequence of conformal transformations to map a Joukowsky airfoil, partially truncated on the upper surface, onto a circle over which the flow problem is solved. Source and doublet singularities are used to create free streamlines simulating shear layers bounding the near wake. The model's simplicity permits extension of the method to airfoil-flap configurations in which trailing-edge stall is assumed on the flap. Williams’ analytical method to calculate the potential flow about two lifting bodies is incorporated in the Joukowsky-arc wake-singularity model to allow for flow separation. The theoretical pressure distributions from these models show good agreement with wind-tunnel measurements.

scholarly journals Experimental and computational investigation for three dimensional duct flow with modified arrangement ribs turbulators

2020 ◽  
pp. 93-93
Author(s):  
Khudheyer Mushatet ◽  
Sarah Nashee
Keyword(s):  
Friction Factor ◽  
Numerical Study ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Duct Flow ◽  
Computational Investigation ◽  
Performance Factor ◽  
Pitch Ratio ◽  
Overall Performance ◽  
Good Agreement

A combined numerical and experimental study is conducted to test the heat transfer enhancement and friction factor characteristics for a rectangular duct fitted with three cases of ribs turbulators: continuous ribs (CR), intermittent-continuous-intermittent ribs (ICIR) and intermittent ribs (IR). Experiments are conducted within a turbulent flow for Reynolds numbers values varied from 10000 to 35000, pitch ratio (p/e) equal to 5 and height ratio (e/H) of 0.33. The numerical study carried out using ANSYS FlUENT17.2. The turbulence is modeled by using k-? model. The results showed that the case of intermittent ribs provide the highest over performance factor while the continuous ribs indicate less overall performance factor among the considered cases. In addition, the results show that the highest values of the friction factor are marked from the case of intermittent ribs (IR) and then the case of intermittent-continuous-intermittent ribs (ICIR) followed by continuous rib case (CR). The continuous rib case showed the lowest friction factor. The experimental results showed a good agreement with the computational results.

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