Showing papers on "Diffuser (thermodynamics) published in 2005"

Bell-shaped film cooling holes for turbine airfoil

Abstract: A turbine airfoil a plurality of cooling holes formed in the external surface of the airfoil in fluid communication with a cooling circuit. The cooling holes have a metering section and a diffuser section opening to the external surface of the airfoil. The diffuser section has top, bottom and opposed side walls, where at least the opposed side walls and one or the other of the top and bottom walls of the diffuser section have a downstream diverging, bell-shaped configuration for achieving a flow of the cooling film from the cooling circuit with enhanced spread, enhanced attachment and less turbulence to a downstream surface of the airfoil local to each respective cooling hole.

Interactions Between Shock and Acoustic Waves in a Supersonic Inlet Diffuser

Abstract: The interactions between shock and acoustic waves in a supersonic inlet diffuser are investigated numerically. The model treats the viscous flowfield in an axisymmetric, mixed-compression inlet operating under supercritical conditions. It is solved by means of a finite-volume approach using a four-stage Runge-Kutta scheme for temporal derivatives and the Harten-Yee upwind total-variation-diminishing scheme for spatial terms. Various distinct flow structures, including shock/boundary-layer and shock/shock interactions, are studied under the effects of externally imposed pressure oscillations at the diffuser exit over a wide range of forcing frequencies and amplitudes. As a result of the terminal shock oscillation induced by the impressed disturbances and the cyclic variation of the oblique/normal shock intersection, large vorticity fluctuations are produced in the radial direction. The characteristics of the shock/boundary-layer interactions (such as the size of the separation bubble, the terminal shock configuration, and the vorticity intensity) are also greatly influenced by the acoustic-driven shock oscillation. The overall response of the inlet aerodynamics to acoustic waves can be characterized by the mass-transfer and acoustic-admittance functions at the diffuser exit. Their magnitudes decrease with increasing frequency. A supersonic inlet acts as an effective acoustic damper, absorbing disturbances arising downstream. Severe flow distortion, however, may arise from shock oscillation and subsequently degrade the combustor performance.

Unsteady Hydrodynamic Forces due to Rotor-Stator Interaction on a Diffuser Pump With Identical Number of Vanes on the Impeller and Diffuser

Abstract: Experimental and computational study was developed for unsteady hydrodynamic forces on a diffuser pump impeller excited by the interaction between the impeller and the vaned diffuser with the same number of vanes as impeller. Unsteady flow calculations are made using commercially available CFD software, CFX-TASCflow, as well as the two-dimensional vortex method. Calculated pressure and fluid forces on the impeller show good agreement with measured ones. It has been demonstrated that the fluid forces on the impeller with the same number of vanes as the vaned diffuser are smaller compared with other combinations of vane numbers. However, the pressure fluctuations are found to be greater than other cases.

Preliminary Design of a 2D Supersonic Inlet to Maximize Total Pressure Recovery

Abstract: *† This paper provides a method of preliminary design for a two-dimensional, mixed compression, two-ramp supersonic inlet to maximize total pressure recovery and match the mass flow demand of the engine. For an on-design condition, the total pressure recovery is maximized according to the optimization criterion, and the dimensions of the inlet in terms of ratios to the engine face diameter are calculated. The optimization criterion is defined such that in a system of (n-1) oblique shocks and one normal shock in two dimensions, the maximum shock pressure recovery is obtained when the shocks are of equal strength. This paper also provides a method to estimate the total pressure recovery for an off-design condition for the specified inlet configuration. For an off-design condition, conservative estimation of the total pressure recovery is given so that performance of the engine at the off-design condition can be estimated. To match the mass flow demand of the engine, the second ramp angle is adjusted and the open/close schedule of a bypass door is determined. The effects of boundary layer are not considered for the supersonic part of the inlet, however friction and expansion losses are considered for the subsonic diffuser. Nomenclature α = Angle of attack j β = The installation angle of the j th ramp γ = The ratio of specific heats j δ = The flow deflection angle of the j th shock (j th ramp half angle) d θ = The half expansion angle of the subsonic diffuser j θ = The shock wave angle of the j th shock * A = The cross section area of flow tube at throat where the flow is sonic j A = The cross section area of flow at j th station point 54 AR = The ratio of inlet cross section areas at station points 5 and 4 5 d = The engine diameter at station point 5 (engine face) 6 d = The engine diameter at station point 6 (fan face) H = Flight altitude c h , 0 h = The captured freestream flow tube height i h = The height of inlet at the entry, measured perpendicular to the flight direction j h = The height of j

Numerical and Experimental Analysis of an Axial Flow Left Ventricular Assist Device: The Influence of the Diffuser on Overall Pump Performance

Abstract: Thousands of adult cardiac failure patients may benefit from the availability of an effective, long-term ventricular assist device (VAD). We have developed a fully implantable, axial flow VAD (LEV-VAD) with a magnetically levitated impeller as a viable option for these patients. This pump's streamlined and unobstructed blood flow path provides its unique design and facilitates continuous washing of all surfaces contacting blood. One internal fluid contacting region, the diffuser, is extremely important to the pump's ability to produce adequate pressure but is challenging to manufacture, depending on the complex blade geometries. This study examines the influence of the diffuser on the overall LEV-VAD performance. A combination of theoretical analyses, computational fluid (CFD) simulations, and experimental testing was performed for three different diffuser models: six-bladed, three-bladed, and no-blade configuration. The diffuser configurations were computationally and experimentally investigated for flow rates of 2-10 L/min at rotational speeds of 5000-8000 rpm. For these operating conditions, CFD simulations predicted the LEV-VAD to deliver physiologic pressures with hydraulic efficiencies of 15-32%. These numerical performance results generally agreed within 10% of the experimental measurements over the entire range of rotational speeds tested. Maximum scalar stress levels were estimated to be 450 Pa for 6 L/min at 8000 rpm along the blade tip surface of the impeller. Streakline analysis demonstrated maximum fluid residence times of 200 ms with a majority of particles exiting the pump in 80 ms. Axial fluid forces remained well within counter force generation capabilities of the magnetic suspension design. The no-bladed configuration generated an unacceptable hydraulic performance. The six-diffuser-blade model produced a flow rate of 6 L/min against 100 mm Hg for 6000 rpm rotational speed, while the three-diffuser-blade model produced the same flow rate and pressure rise for a rotational speed of 6500 rpm. The three-bladed diffuser configuration was selected over the six-bladed, requiring only an incremental adjustment in revolution per minute to compensate for and ease manufacturing constraints. The acceptable results of the computational simulations and experimental testing encourage final prototype manufacturing for acute and chronic animal studies.

Numerical Analysis of Flow Phenomena related to the Unstable Energy-Discharge Characteristic of a Pump-Turbine in Pump Mode

Abstract: Regions of positive slope in the pressure-discharge characteristics are one of the major concerns in design and operation of centrifugal pumps, as they are limiting the admissible operating range to values above the critical discharge. The industrial pump turbine of specific speed ν=0.42 (nq=66 min-1) proposed as QNET-CFD test case TA6-04 shows a marked saddle in the energy-discharge characteristic associated to a sudden drop of efficiency versus discharge at part load. The pump-turbine consists of a shrouded impeller with five blades, a diffuser with 22 guide and stay vanes and a spiral casing. CFD flow simulations on a reduced model were carried out with a finite volume Navier-Stokes code (CFX-5.7) using block- tructured hexahedral meshes and the Menter-SST Turbulence model. Control of numerical quality has been performed. Reduced models with relatively low computational effort (mixing plane interface) already permit to capture the drop in efficiency and energy coefficient to analyze the flow phenomena inducing the drop of the energy coefficient Ψ that occurs at partial discharge. Analysis of local flow patterns and energy and velocity distributions at the rotor-stator interface that are related to the onset of recirculation are presented.

PIV Measurements of Flow in a Centrifugal Blood Pump: Steady Flow

Abstract: Magnetically suspended left ventricular assist devices have only one moving part, the impeller. The impeller has absolutely no contact with any of the fixed parts, thus greatly reducing the regions of stagnant or high shear stress that surround a mechanical or fluid bearing. Measurements of the mean flow patterns as well as viscous and turbulent stresses were made in a shaft-driven prototype of a magnetically suspended centrifugal blood pump at several constant flow rates (3-9 L/min) using particle image velocimetry (PIV). The chosen range of flow rates is representative of the range over which the pump may operate while implanted. Measurements on a three-dimensional measurement grid within several regions of the pump, including the inlet, blade passage, exit volute, and diffuser are reported. The measurements are used to identify regions of potential blood damage due to high shear stress and/or stagnation of the blood, both of which have been associated with blood damage within artificial heart valves and diaphragm-type pumps. Levels of turbulence intensity and Reynolds stresses that are comparable to those in artificial heart valves are reported. At the design flow rate (6 L/min), the flow is generally well behaved (no recirculation or stagnant flow) and stress levels are below levels that would be expected to contribute to hemolysis or thrombosis. The flow at both high (9 L/min) and low (3 L/min) flow rates introduces anomalies into the flow, such as recirculation, stagnation, and high stress regions. Levels of viscous and Reynolds shear stresses everywhere within the pump are below reported threshold values for damage to red cells over the entire range of flow rates investigated; however, at both high and low flow rate conditions, the flow field may promote activation of the clotting cascade due to regions of elevated shear stress adjacent to separated or stagnant flow.

Flow Study in the Impeller–Diffuser Interface of a Vaned Centrifugal Fan

Abstract: In order to better understand the behavior of the fluid flow in vaned centrifugal fans, theoretical and experimental work has been carried out on unsteady three-dimensional (3D) flows. Particular attention is given to the flows located at the rotor-stator interface. This zone is the seat of strong interactions between the moving part and the fixed part. This phenomenon has as consequences: Strongly unsteady flow, fluctuating forces on the stator blades, and an efficiency decrease. This work is part of a project which main objective is the aeroacoustic optimization of high speed centrifugal fans. We present in this paper the first results, mainly aerodynamic ones, which will be used thereafter as an input data to aeroacoustic modeling. A numerical simulation tool was used in order to determine the kinematics and the dynamics of these flows. The measurements of the steady and unsteady flow characteristics allowed a comparison of the theoretical and experimental results.

High efficiency fan cooling holes for turbine airfoil

Abstract: A turbine airfoil includes a leading edge and an axially spaced-part trailing edge, the leading edge having an axially-extending external surface curvature. A cooling circuit in the airfoil includes cooling holes formed in the leading edge along the span axis of the airfoil. The cooling holes have a diffuser section communicating with the leading edge surface. The diffuser section has four opposed walls defining a generally quadralinear exit opening on the surface of the leading edge. One of the diffuser walls has a convex curvature that approximates the external surface curvature of the leading edge whereby fluid flow from the cooling hole exits is evenly dispersed and spread along land portions of the leading edge adjacent the cooling holes.

Computational study on the internal layer in a diffuser

Abstract: We report an internal layer found in the turbulent flow through an asymmetric planar diffuser using large-eddy simulation; we discuss five issues relevant to the internal layer: definition and identification, conditions for occurrence, connection with its outer flow, similarity with other equilibrium flows, and growth. The present internal layer exists in a region with stabilized positive skin friction downstream of a sharp reduction. The streamwise pressure gradient changes suddenly from slightly favourable to strongly adverse at the diffuser throat, and relaxes in a prolonged mildly adverse region corresponding to the skin friction plateau. Development of the internal layer into the outer region is slow, in contrast to the internal layers previously identified from certain external boundary-layer flows where the sudden change in streamwise pressure gradient is from strongly adverse to mildly favourable. Signatures of the internal layer include an inflectional point in the wall-normal profiles of streamwise turbulence intensity, and a well-defined logarithmic slope in the mean streamwise velocity underneath a linear distribution extending to the core region of the diffuser. Some of these characteristics bear a certain resemblance to those existing in the C-type of Couette–Poiseuille turbulent flows. Frequency spectrum results indicate that application of strong adverse pressure gradient at the diffuser throat enhances the low-frequency content of streamwise turbulent fluctuations. Inside the internal layer, the frequency energy spectra at different streamwise locations, but with the same wall-normal coordinate, nearly collapse. Two-point correlations with streamwise, wall-normal and temporal separations were used to examine connections between fluctuations inside the internal layer and those in the core region of the diffuser where the mean streamwise velocity varies linearly with distance from the wall. Galilean decomposition of instantaneous velocity vectors reveals a string of well-defined spanwise vortices outside the internal layer. The internal layer discovered from this study provides qualified support for a conjecture advanced by Azad &

Thermal Characterization of Non-Raised Floor Air Cooled Data Centers Using Numerical Modeling

Abstract: Data center equipment almost always represents a high expenditure capital investment to the customer, and is often operated without any down time. Data com equipment is typically designed to operate at a rack air inlet temperature of between 10 and 35°C, and a violation of this specification can diminish electronic device reliability and even lead to failure in the field. Thus, it is of paramount importance, from a reliability perspective, to sufficiently understand these systems. A representative non-raised floor data center system was numerically modeled and the data generated from a parametric study was analyzed. The model constitutes a half symmetry section of a 40 rack data center that is arranged in a cold aisle-hot aisle fashion. The effect of several input variables, namely, rack heat load, rack flow rate, rack temperature rise, diffuser flow rate, diffuser location, diffuser height, diffuser pitch, ceiling height, hot exhaust air return vent location, and non-uniformity in rack heat load, was studied. Temperature data was collected at several locations at the inlet to the racks. Statistical analysis was carried out to describe trends in the data.Copyright © 2005 by ASME

Turbine blade cooling system

Abstract: Efficient cooling of a stage of gas turbine engine turbine blades (36) is achieved by first reducing the pressure of the cooling air after it has been bled from the annulus of the compressor (12) by passing it through a diffuser (30), to a pressure magnitude lower than is required at entry to the turbine blades, then re-pressurizing the bled air up to the required entry pressure, by passing it through a radial compressor defined by a cowl (44) positioned in close spaced, co-rotational relationship with the downstream face of the associated turbine disk (34).

Experimental and computational investigation of an aeroramp injector in a mach four cross flow

Abstract: An experimental and computational study of an aerodynamic ramp (aeroramp) injector was conducted at Virginia Tech. The aeroramp consisted of an array of two rows with two columns of flush-wall holes that induce vorticity and enhance mixing. The holes were spaced four diameters apart in the streamwise direction with two diameters transverse spacing between them. For comparison, a single-hole circular injector with the same area angled downstream at 30 degrees was also examined. Test conditions involved sonic injection of helium heated to 313 K, to safely simulate hydrogen into a Mach 4 air cross-stream with average Reynolds number 5.77 e+7 per meter at a jet to freestream momentum flux ratio of 2. Sampling probe measurements were utilized to determine the local helium concentration. Pitot and cone-static pressure probes and a diffuser thermocouple probe were employed to document the flow. This allowed total pressure losses to be determined. The numerical flow solver used was GASP v. 4.2. The inviscid fluxes were computed in three dimensions using third-order AUSM+ with modified ENO limiting. The AUSM+ algorithm was chosen because of its good resolution of shock discontinuities and its efficiency. The Wilcox k-9 (1998) turbulence model was used. The main results of this work can be summarized as: 1) The mixing efficiency value of this aeroramp which was optimized at Mach 2.4 for hydrocarbon fuel was only slightly higher than that of the single-hole injector at these flow conditions, 2) the mass-averaged total pressure loss parameter showed that the aero-ramp and single-hole injectors had the same overall losses, 3)The CFD was unable to accurately predict the quantitative mixing data produced by the experiment, however the qualitative comparisons of the injectors using the CFD predictions agreed with the experiment.

System, method, and apparatus for designing streamline traced, mixed compression inlets for aircraft engines

Abstract: An advanced aperture inlet (AAI) uses a three-dimensional, mixed compression inlet design derived from computational fluid dynamics (CFD) by streamline tracing a supersonic section from an axisymmetric mixed compression inlet solution. The axisymmetric design is used to obtain a CFD solution with slip wall boundaries at the inlet design point and serves as a flow field generator for the AAI. The AAI geometry is obtained by projecting a desired aperture shape onto a surface model of the external oblique shock. Streamline seeds are located on the projected aperture segments and transferred into the CFD solution space. The streamlines generated by these seeds inside the CFD solution space are then used as a wireframe to define the supersonic diffuser back to the throat location. Traditional design techniques are then used to define the subsonic diffuser from the inlet throat to the engine face.

Improved Diffuser/Volute Combinations for Centrifugal Compressors

Abstract: Internal volutes have a constant outer radius, slightly larger than the diffuser exit radius, and the circumferential increase of the cross section is accommodated by a decrease of the inner radius. They allow the design of compact radial compressors and hence are very attractive for turbochargers and high-pressure pipeline compressors where small housing diameters have a favorable impact on weight and cost. Internal volutes, however, have higher losses and lower pressure rise than external ones in which the center of the cross sections is located at a larger radius than the diffuser exit. This paper focuses on the improvement of the internal volute performance by taking into account the interaction between the diffuser and the volute. Two alternative configurations with enhanced aerodynamic performance are presented. A first one features a novel, non-axi-symmetric diffuser/internal volute combination. It demonstrates an increased pressure ratio and lower loss over most of the operating range at all rotational speeds. The circumferential pressure distortion at off design operation is slightly larger than in the original configuration with a concentric vaneless diffuser. Alternatively, a parallel-walled Low-Solidity Diffuser (LSD) with an internal volute allows a reduction of the unsteady load on the impeller and an improved performance close to the one of a vaneless concentric diffuser with a large external volute.Copyright © 2005 by ASME

Passenger airbag with a diffuser

Abstract: A three-panel, passenger-side airbag includes main, right, and left panels, and a diffuser provided adjacent a rear side of the main panel. The main panel includes a front impact said and a rear inflation side. The front impact side is formed of upper and lower portions. When the airbag is inflated, the upper portion is configured to be directed toward the upper torso of a passenger and the lower portion in configured to be directed toward the passenger's lower torso, groin, and legs. The diffuser is configured to direct inflation gas toward the lower portion so that the lower portion inflates faster than the upper portion.

Two phase flow conditioner for pumping gassy well fluid

Abstract: A centrifugal pump pumps well fluid with a high gaseous content by conditioning the well fluid with a conditioning impeller and conditioning diffuser design for use with gaseous well fluid. The conditioning impellers have vanes that are curved with a leading edge that is rotationally forward and axially below, or upstream, of a trailing edge. The outer end of the leading edge is rotationally forward of the inner end of the leading edge, which forces the well fluid radially inward and mixes the gas and liquids in the well fluid. The conditioning diffusers have blades that are curved with a leading edge that is rotationarily rearward and axially below a trailing edge. The blades are portions of a sphere, with a concaved side receiving well fluid from the conditioning impellers. The spherical shape forces the well fluid radially inward and axially upward.

Effect of Magnetohydrodynamics Interaction in Various Parts of Diffuser on Inlet Shocks: Experiment

Abstract: The effects of external magnetic and electric fields on the position of attached shocks in a supersonic diffuser were studied Experiments were conducted at a Mach number at the diffuser inlet of M = 43 The working gas was Xe plasma, formed using a reflected shock tube with an accelerating convergent-divergent nozzle Magnetohydrodynamic experiments with an external transverse electric field in the decelerating and accelerating regimes and experiments with a longitudinal electric field were carried out The interaction of the flow with the external fields in different parts of the diffuser was achieved by circulating current through different segmented electrodes It has been found that application of external fields near the inlet leading edge is the most efficient

System for coupling flow from a centrifugal compressor to an axial combustor for gas turbines

Abstract: A system is provided for aerodynamically coupling air flow from a centrifugal compressor (200) to an axial combustor (202). The system includes a diffuser (204), a deswirl assembly (206), combustor inner and outer annular liners (226, 228), a combustor dome (230), and a curved annular plate (244). The diffuser (204) has an inlet (214) that communicates with the centrifugal compressor (200), an outlet (216), and a flow path (218) that extends radially outward. The deswirl assembly (206) has an inlet (220) that communicates with the diffuser outlet (216) to receive air flowing in a radially outward direction, an outlet (222), and a flow path (224) configured to redirect the air in a radially inward and axial direction through the deswirl assembly outlet (222) at an angle toward a longitudinal axis (207). The curved annular plate (244) is coupled to combustor inner and outer annular liner upstream ends (234, 238) to form a combustor subplenum (241) therebetween and has a first opening (250) and a second opening (252) formed therein, the first opening (250) aligned with the deswirl assembly outlet (222) to receive air discharged therefrom.

Methods and apparatus for cooling combustion turbine engine components

Abstract: A turbine nozzle cooling sub-system is provided. The sub-system includes at least one turbine nozzle segment. The segment includes an arcuate, radially outermost endwall, an arcuate, radially innermost endwall, and at least one airfoil vane. The endwalls each include at least one open passage. The airfoil vane extends between and is coupled to the endwalls. The vane further includes a cavity, a leading edge, a trailing edge, and an airfoil vane external surface. The cavity includes an airfoil vane internal surface and a plurality of turbulators. The cavity and the open passages are in flow communication such that an airfoil cooling air stream flow is facilitated. The sub-system also includes at least one diffuser in flow communication with a compressor assembly and the segment. The diffuser includes at least one diffuser wall and cavity. The diffuser wall extends from the compressor assembly to the segment such that a channeling of the airfoil cooling air stream to the segment is facilitated. The airfoil cooling air stream includes at least a portion of a compressor assembly discharge air stream flow.

Disturbances from shock/boundary-layer interactions affecting upstream hypersonic flow

Abstract: Laminar-turbulent transition is critical for vehicles which fly at hypersonic speeds for extended periods. To improve on existing correlations, prediction methods that incorporate knowledge of the transition mechanisms are necessary and now feasible. Purdue continues to develop the Boeing/AFOSR Mach-6 Tunnel to seek quiet flow at high Reynolds numbers, with noise levels comparable to flight. It has been shown previously that quiet flow is only possible at low stagnation pressures probably because a separation bubble develops on the bleed lip. A new upstream portion of the nozzle was built without the high polish, and was found to increase the quiet-flow stagnation pressure from 8 psia to 20 psia. When laminar boundary layers are maintained on the walls of the nozzle, the flow becomes separated about two-thirds of the distance down the nozzle. It is shown here that this separation is caused by shocks from the sting mount in the diffuser that disturb the boundary layer far upstream. Attempts have been made to try to prevent these disturbances from traveling so far upstream, but have met with little success. This limits the ability to test models using the quiet flow.

Rotor-Stator Interactions in a Vaned Diffuser Radial Flow Pump

Abstract: The paper presents an analysis of unsteady effects associated with rotor stator interactions in a vaned diffuser radial flow pump. The experimental data have been obtained by 2D Particle Image Velocimetry at mid height between hub and shroud, in the impeller outlet zone and within a vaned diffuser passage. Unsteadiness is discussed first in the impeller outlet zone and then along a passage of the vaned diffuser.Copyright © 2005 by ASME

Effects of Diffuser Vane Geometry on Interaction Noise Generated from a Centrifugal Compressor

Abstract: The characteristics of interaction tone noise radiated from a centrifugal compressor with a vaned diffuser are discussed by experiments, including visualization techniques using the oil-film method. Research attention is paid to the leading edge geometries of the diffuser vanes that are deeply related to the generation mechanism of the interaction tone noise. The compressor-radiated noise can be reduced by several decibels by setting some clearances in both the hub and shroud surfaces of the diffuser wall along with some decline in the pressure-rise coefficient. Since the decline turned out to be caused by the flow impingement and also by the secondary flow within the diffuser passages, several new types of diffuser vane geometries which do not detract from both the performance and noise level are developed and utilized for the experiments. The presented diffuser vane geometries will offer a few basic guidelines for the diffuser vane design.

Fuel cell gas distribution

Abstract: A fuel cell comprising a membrane-electrode assembly having an anode electrode face; an anode plate adjacent said membrane-electrode assembly electrode face and coupled thereto by a sealing gasket. The sealing gasket, electrode face and anode plate together define a fluid containment volume for delivery of anode fluid to the electrode face. A sheet of porous diffuser material is situated in the fluid containment volume and having at least one plenum defined between at least one lateral edge of the sheet of diffuser material and the sealing gasket. Fluid for delivery to an active surface of the membrane-electrode assembly may be delivered by the plenum and by diffusion through the diffuser material to such an extent that fluid flow channels in the anode plate are not required.

Investigation of Wall Function and Turbulence Model Performance within the Wind Code

Abstract: A series of computational analyses is performed using three geometries to assess the performance of wall functions and various turbulence models within the Wind flow solver. The study simulates incompressible flow over a flat plate, incompressible flow through an asymmetric diffuser with separation, and flow through a dual-stream subsonic nozzle. Mentor’s SST and Chien’s K-e turbulence models were used. The grids had initial spacings at the wall ranging from y+=1 to y+=60 to assess the performance of the wall functions. Both two-equation turbulence models were found to work well in the presence of a neutral or favorable pressure gradient; however the SST model clearly performed better when an adverse pressure gradient was present. As expected, Wind’s wall functions were able to adequately predict gross flowfield features in attached flow, but performed poorly with separated flow.

Model Reduction of an Actively Controlled Supersonic Diffuser

Abstract: A model reduction test case is presented, which considers flow through an actively controlled supersonic diffuser. The problem setup and computational fluid dynamic (CFD) model are described. Sample model reduction results for two transfer functions of interest are then presented.