Aerodynamic Torque Characteristics of Butterfly Valves in Compressible Flow

1989 ◽  
Vol 111 (4) ◽  
pp. 392-399 ◽  
Author(s):  
M. J. Morris ◽  
J. C. Dutton
Keyword(s):  
Compressible Flow ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Operating Pressure ◽  
Pressure Gradients ◽  
Flow Conditions ◽  
Trailing Edges ◽  
Operating Points ◽  
Aerodynamic Torque ◽  
Flow Separation And Reattachment

The results of an experimental investigation of the aerodynamic torque characteristics of butterfly valves under compressible flow conditions are reported. Both three-dimensional prototype valves and two-dimensional planar models have been studied at choked and unchoked operating points. Other parameters investigated include the operating pressure ratio across the valve, the valve disk angle, and the disk shape. The results demonstrate the importance of flow separation and reattachment phenomena on the valve aerodynamic torque characteristics, the importance of disk shape at intermediate angles, and the sensitivity of the torque to the valve disk geometry near the leading and trailing edges where extreme pressure gradients can occur.

Compressible Flowfield Characteristics of Butterfly Valves

1989 ◽  
Vol 111 (4) ◽  
pp. 400-407 ◽  
Author(s):  
M. J. Morris ◽  
J. C. Dutton
Keyword(s):  
Flow Separation ◽  
Pressure Ratio ◽  
Disk Surface ◽  
Surface Flow ◽  
Operating Conditions ◽  
Local Geometry ◽  
Operating Pressure ◽  
Butterfly Valve ◽  
Pressure Distributions ◽  
Flow Separation And Reattachment

The results of an experimental investigation into the flowfield characteristics of butterfly valves under compressible flow operating conditions are reported. The experimental results include Schlieren and surface flow visualizations and flowfield static pressure distributions. Two valve disk shapes have been studied in a planar, two-dimensional test section: a generic biconvex circular arc profile and the midplane cross-section of a prototype butterfly valve. The valve disk angle and operating pressure ratio have also been varied in these experiments. The results demonstrate that under certain conditions of operation the butterfly valve flowfield can be extremely complex with oblique shock waves, expansion fans, and regions of flow separation and reattachment. In addition, the sensitivity of the valve disk surface pressure distributions to the local geometry near the leading and trailing edges and the relation of the aerodynamic torque to flow separation and reattachment on the disk are shown.

Inverse Design of 3D Multi-Stage Transonic Fans at Dual Operating Points

2013 ◽  
Author(s):  
James H. Page ◽  
Paul Hield ◽  
Paul G. Tucker
Keyword(s):  
Design Method ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Inverse Design ◽  
Flow Angle ◽  
Trade Offs ◽  
Multi Stage ◽  
Full Speed ◽  
Computational Fluid Dynamics Cfd ◽  
Operating Points

Semi-inverse design is the automatic re-cambering of an aerofoil, during a computational fluid dynamics (CFD) calculation, in order to achieve a target lift distribution while maintaining thickness, hence “semi-inverse”. In this design method, the streamwise distribution of curvature is replaced by a stream-wise distribution of lift. The authors have developed an inverse design code based on the method of Hield (2008) which can rapidly design three-dimensional fan blades in a multi-stage environment. The algorithm uses an inner loop to design to radially varying target lift distributions, an outer loop to achieve radial distributions of stage pressure ratio and exit flow angle, and a choked nozzle to set design mass flow. The code is easily wrapped around any CFD solver. In this paper, we describe a novel algorithm for designing simultaneously for specified performance at full speed and peak efficiency at part speed, without trade-offs between the targets at each of the two operating points. We also introduce a novel adaptive target lift distribution which automatically develops discontinuous changes of calculated magnitude, based on the passage shock, eliminating erroneous lift demands in the shock vicinity and maintaining a smooth aerofoil.

Numerical and Experimental Investigation of Pulsating Flow Effect on a Nozzled and Nozzleless Mixed Flow Turbine for an Automotive Turbocharger

2014 ◽  
Author(s):  
M. H. Padzillah ◽  
M. Yang ◽  
W. Zhuge ◽  
R. F. Martinez-Botas
Keyword(s):  
Pressure Ratio ◽  
Turbine Blades ◽  
Computational Cost ◽  
Operating Conditions ◽  
Pulsating Flow ◽  
Angle Distribution ◽  
Operating Pressure ◽  
Flow Conditions ◽  
Flow Angle ◽  
Turbine Speed

To achieve better flow guidance into the turbine blades, nozzle vanes were added as an integral part of the stator design. However, the full investigation that directly addresses the comparison between the two turbine arrangements under pulsating flow conditions is still not available in literature. This work represents the first attempt to observe differences, particularly in the circumferential flow angle distribution between both volute arrangements under steady and pulsating flow operating conditions. Experimentally validated Computational Fluid Dynamics (CFD) simulations have been conducted in order to achieve this aim. As the experimental data within the Turbocharger Group at Imperial College are extensive, the simulation procedures are optimized to achieve the best compromise between the computational cost and prediction accuracy. A single operating pressure ratio is selected for the steady and pulsating environment in order to provide consistent comparison for both volute arrangements. The simulation results presented in this work are conducted at the turbine speed of 48000rpm and 60Hz flow frequency for the pulsating flow simulations. The results indicated that there are significant differences in the flow angle behavior for both volutes regardless of the flow conditions (steady or unsteady). It is also found that the differences in flow angle distribution between increasing and decreasing pressure instances during pulsating flow operation is more prominent in the nozzleless volute than its nozzled counterpart.

Effect of Adverse Pressure Gradients on Turbulent Boundary Layers in Axisymmetric Conduits

1957 ◽  
Vol 24 (2) ◽  
pp. 191-196
Author(s):  
J. M. Robertson ◽  
J. W. Holl
Keyword(s):  
Boundary Layer ◽  
Flow Parameter ◽  
Three Dimensional ◽  
Turbulent Boundary Layers ◽  
Pressure Gradients ◽  
Two Dimensional ◽  
Flow Conditions ◽  
Straight Pipe ◽  
Outer Flow ◽  
Dimensional Boundary

Abstract The development of the three-dimensional boundary layer in a diffuser with several discharge arrangements has been studied for air flow, in continuation of the work of Uram (1). The flow conditions in a diffuser when followed by a straight pipe, an additional length of the diffuser, or a jet, are compared. Extension of the method of analysis developed by Ross for two-dimensional layers is presented. In some cases the use of three-dimensionally defined parameters leads to different results. Ross’s (2) unique outer-flow parameter is found to be no longer satisfactory. Other outer parameters are presented as possible substitutes.

scholarly journals Rainbow schlieren measurements in underexpanded jets from square supersonic micro nozzles

2018 ◽  
Vol 180 ◽  
pp. 02058
Author(s):  
Hiroaki Maeda ◽  
Hikaru Fukuda ◽  
Shinichiro Nakao ◽  
Yoshiaki Miyazato ◽  
Yojiro Ishino
Keyword(s):  
Pressure Ratio ◽  
Three Dimensional ◽  
Vortex Sheet ◽  
Quantitative Agreement ◽  
Dimensional Structure ◽  
Operating Pressure ◽  
Underexpanded Jets ◽  
Free Jet ◽  
Rainbow Schlieren Deflectometry ◽  
Rainbow Schlieren

The slightly underexpanded free jet issued from a supersonic micro nozzle with a design Mach number of 1.5 and a square shape of 1 mm × 1 mm at the nozzle exit has been experimentally investigated using the rainbow schlieren deflectometry combined with the computed tomography where the nozzle operating pressure ratio is held constant at 4.0. Density fields in the free jet obtained from the rainbow schlieren deflectometry are the vortex sheet theory proposed by Tam. It is shown that there is good quantitative agreement between experiment and theory. It is shown that the rainbow schlieren deflectometry is a useful tool for studying the three-dimensional structure of shock containing free jets from micro-scale supersonic nozzles.

Analysis of Radial Compressor Performance at Low Pressure Ratios and Compressor Choke

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Adrian Schloßhauer ◽  
Felix Falke ◽  
Johannes Klütsch ◽  
Iris Kreienborg ◽  
Stefan Pischinger
Keyword(s):  
Pressure Ratio ◽  
Three Dimensional ◽  
Measurement Data ◽  
Low Pressure ◽  
Cfd Simulations ◽  
Process Simulations ◽  
Mass Flowrate ◽  
Compressor Performance ◽  
Compressor Map ◽  
Operating Points

Abstract Strong transient engine load steps can result in low pressure ratio (ΠC) compressor operation for single stage turbocharged (TC) systems. For conventional full load TC engine matching using one-dimensional (1D)-engine process simulation, these operating points are of limited relevance and are consequently less studied. However, for the layout of sequential turbocharging systems, low pressure ratio compressor operation has to be thoroughly understood. Therefore, in this paper, three-dimensional (3D)-computational fluid dynamics (CFD) simulations will be presented, which analyze the stationary compressor behavior at low pressure ratios. Operating points at ΠC<1 are investigated by reducing the compressor outlet pressure. The simulation results are validated against measurement data acquired at a stationary hot gas test bench. The compressor performance is quantified by a corrected compressor torque. Opposed to the well-known operation at ΠC>1, the compressor generates power close to zero speed for ΠC<1 (turbine operation). At higher mass flowrates and ΠC<1, the compressor consumes power. Pressure build-up in the wheel is overcompensated by losses in the diffusor and the volute resulting in a net pressure drop across the stage. The 3D-CFD simulations also allow a speed-dependent evaluation of the choking cross section inside the compressor. At low circumferential speeds, compressor choke occurs in the volute or at the wheel outlet. At higher speeds, choking is observed at the wheel inlet. This behavior must be accounted for compressor map extrapolation methods for 1D-engine process simulations in order to correctly predict the choking mass flowrate.

Numerical Investigation of Circumferential Groove Casing Treatment on a Low Speed Contra-Rotating Fan

2019 ◽  
Author(s):  
Martin Heinrich ◽  
Hossein Khaleghi ◽  
Christian Friebe
Keyword(s):  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Flow Conditions ◽  
Low Speed ◽  
Casing Treatment ◽  
Fan Performance ◽  
Circumferential Groove ◽  
Transient Simulations ◽  
Operating Points ◽  
Good Agreement

Abstract This study is aimed at understanding the effects of circumferential groove casing treatment on the performance of a low speed contra-rotating fan. Three dimensional, transient simulations are carried out using the open source CFD library Open-FOAM. The numerical results are validated with experiments for the smooth casing, which show a good agreement. Three treated casing configurations are investigated: 1) grooves at the top of the first rotor, 2) grooves at the top of the second rotor, and 3) grooves at the top of both rotors. Two operating points are simulated for all configurations. Flow inside the grooves is highly dominated by the main and blade passage flows. Grooves increase fan performance at near-stall flow conditions by up to 3 % and reduce pressure fluctuations significantly. Furthermore, they have a larger impact on fan performance when placed on top of the first rotor compared to placing them on top of the second rotor.

Inverse Design of 3D Multistage Transonic Fans at Dual Operating Points

2013 ◽  
Vol 136 (4) ◽  
Author(s):  
James H. Page ◽  
Paul Hield ◽  
Paul G. Tucker
Keyword(s):  
Design Method ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Axial Flow ◽  
Inverse Design ◽  
Flow Angle ◽  
Trade Offs ◽  
Full Speed ◽  
Flow Compressor ◽  
Operating Points

Semi-inverse design is the automatic recambering of an aerofoil during a computational fluid dynamics (CFD) calculation in order to achieve a target lift distribution while maintaining thickness, hence, “semi-inverse.” In this design method, the streamwise distribution of curvature is replaced by a streamwise distribution of lift. The authors have developed an inverse design code based on the method of Hield (2008, “Semi-Inverse Design Applied to an Eight Stage Transonic Axial Flow Compressor,” ASME Paper No. GT2008-50430), which can rapidly design three-dimensional fan blades in a multistage environment. The algorithm uses an inner loop to design to radially varying target lift distributions, an outer loop to achieve radial distributions of stage pressure ratio and exit flow angle, and a choked nozzle to set design mass flow. The code is easily wrapped around any CFD solver. In this paper, we describe a novel algorithm for designing simultaneously for specified performance at full speed and peak efficiency at part speed, without trade-offs between the targets at each of the two operating points. We also introduce a novel adaptive target lift distribution, which automatically develops discontinuous changes of calculated magnitude, based on the passage shock, eliminating erroneous lift demands in the shock vicinity and maintaining a smooth aerofoil.

Optimization of a Diffuser With Splitter by Numerical Simulation

1993 ◽  
Author(s):  
P. Drtina ◽  
P. Dalbert ◽  
K. Rütti ◽  
A. Schachenmann
Keyword(s):  
Numerical Simulation ◽  
Compressible Flow ◽  
Three Dimensional ◽  
Design Procedure ◽  
Navier Stokes ◽  
Experimental Investigations ◽  
Recovery Coefficient ◽  
Radial Compressor ◽  
Operating Points ◽  
Pressure Recovery Coefficient

Three-dimensional, viscous, and compressible flow calculations have been performed in order to improve the performance of a radial compressor diffuser with splitter. All calculations were carried out applying a commercially available finite-volume Navier-Stokes code. Diffuser design procedure, grid generation and boundary conditions are described in detail. For each diffuser type several operating points ranging from the surge limit to choke were considered. Velocity distributions showing regions of separation are discussed for different diffuser geometries. The downstream evolution of the pressure recovery coefficient is given along both diffuser channels. Calculations have been verified by experimental investigations on full scale diffuser prototypes providing pressure values at defined locations.

scholarly journals A Three-Dimensional Unsteady CFD Model of Compressor Stability

2006 ◽  
Author(s):  
R. V. Chima
Keyword(s):  
Input Data ◽  
Body Force ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Rotating Stall ◽  
The Body ◽  
Navier Stokes ◽  
Blade Row ◽  
Operating Points

A three-dimensional unsteady CFD code called CSTALL has been developed and used to investigate compressor stability. The code solved the Euler equations through the entire annulus and all blade rows. Blade row turning, losses, and deviation were modeled using body force terms which required input data at stations between blade rows. The input data was calculated using a separate Navier-Stokes turbomachinery analysis code run at one operating point near stall, and was scaled to other operating points using overall characteristic maps. No information about the stalled characteristic was used. CSTALL was run in a 2-D throughflow mode for very fast calculations of operating maps and estimation of stall points. Calculated pressure ratio characteristics for NASA stage 35 agreed well with experimental data, and results with inlet radial distortion showed the expected loss of range. CSTALL was also run in a 3-D mode to investigate inlet circumferential distortion. Calculated operating maps for stage 35 with 120 degree distortion screens showed a loss in range and pressure rise. Unsteady calculations showed rotating stall with two part-span stall cells. The paper describes the body force formulation in detail, examines the computed results, and concludes with observations about the code.

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