The Effect of Blade Curving on Flow Characteristics in Rectangular Turbine Stator Cascades With Different Incidences

1991 ◽  
Author(s):  
Zhongqi Wang ◽  
Wanjin Han ◽  
Wenyuan Xu
Keyword(s):  
Static Pressure ◽  
Flow Characteristics ◽  
Streamwise Vortices ◽  
Flow Losses ◽  
Aerodynamic Loading ◽  
Turbine Stator ◽  
Pressure Distributions ◽  
Outlet Flow ◽  
Inlet Conditions ◽  
Negative Gradient

In a low speed plane cascade tunnel, the outlet flow fields and the static pressure distributions on blade surfaces of the turbine rectangular stator cascades with a small aspect ratio (s=0.68) were measured in detail. The experimental results show that the blade curving can form the negative gradient of static pressure along the blade height in the lower region of the cascade and the positive one in the upper region. This can lead to the reduction of the intensity of the streamwise vortices and the aerodynamic loading on both sides of the blades and the endwalls. Therefore, the end crosswise secondary flow losses are decreased considerably. The use of the curvilinear leaned blades can not only improve the flow characteristics in the stator cascades, but also provide good inlet conditions for rotor cascades.

ANALYSIS OF THE EFFECTS OF MASS-INJECTION AT THE LEADING EDGE ON CAVITY FLOW CHARACTERISTICS

2009 ◽  
Vol 23 (03) ◽  
pp. 413-416 ◽  
Author(s):  
JI FEI WU ◽  
ZHAO LIN FAN ◽  
XIN FU LUO
Keyword(s):  
High Speed ◽  
Static Pressure ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Cavity Flow ◽  
Fluctuating Pressure ◽  
Pressure Distributions ◽  
Mass Injection ◽  
Varying Mass ◽  
Hole Number

An experimental investigation was conducted in a high speed wind tunnel to explore the effects of mass-injection on cavity flow characteristics. Detailed static-pressure and fluctuating pressure measurements were obtained at the cavity floor to enable the effects of the mass-injection at the leading edge to be determined. Results indicate that varying mass-injection hole number and the flux rate of mass-injection has no significant effect on cavity flow characteristics. However, mass-injection can reduce the cavity static pressure gradient when the cavity flow type is transitional-cavity flow. The study also indicates that Mach number can influence the effect of mass-injection on cavity fluctuating pressure distributions, and at supersonic speeds, mass-injection can suppress the cavity tones effectively.

Base Flow Characteristics of a Linear Aerospike Nozzle Segment

1973 ◽  
Vol 95 (1) ◽  
pp. 353-359 ◽  
Author(s):  
T. J. Mueller ◽  
W. P. Sule
Keyword(s):  
Static Pressure ◽  
Pressure Ratio ◽  
Flow Characteristics ◽  
Flow Region ◽  
Base Flow ◽  
Base Pressure ◽  
Wake Flow ◽  
Pressure Distributions ◽  
Base Bleed ◽  
Aerospike Nozzle

The separated base flow region within a linear aerospike nozzle segment is investigated experimentally in an ejector-diffuser system. The nozzle-diffuser system and base pressure characteristics are described over the pressure ratio range from the “open wake” to the “closed wake” operation. Schlieren photographs and static pressure distributions along the test section centerline and top contour describe the transition, from “open wake” to “closed wake” flow fields. Base pressure and static pressure distributions are utilized to present the effects of a ramp diffuser. The effects of base bleed on the base pressure ratio and structure of the nozzle flow field are also presented.

Circumferential Flow Differences in the Double-Sided Centrifugal Compressor With Non-Balanced Inlets

2016 ◽  
Author(s):  
Ce Yang ◽  
Yixiong Liu ◽  
Wangxia Wu ◽  
Lei Jing ◽  
Benjiang Wang ◽  
...  
Keyword(s):  
Flow Rate ◽  
Centrifugal Compressor ◽  
Axial Velocity ◽  
Static Pressure ◽  
Internal Flow ◽  
Circumferential Direction ◽  
Flow Structures ◽  
Blade Passage ◽  
Pressure Distributions ◽  
Inlet Conditions

A double-sided centrifugal compressor consists of two impellers whose inlets are non-balanced, with one side of the impeller connected to the straight duct, and the other connected to the bending duct. This leads to the differences in the inlet conditions of the double-sided impeller, resulting in the differences in the flow structures of the rear impeller along the circumferential direction. In this work, aiming at analyzing the flow structures of the rear impeller, diffuser and volute internal in three flow rate conditions, the internal flow field of the double-sided centrifugal compressor was calculated in a numerical method. It is found that the inlet bending duct results in significant inlet axial velocity difference of the rear impeller along circumferential direction. The axial velocity differences at high span positions become more obvious with the increase of the flow rate. Moreover, the jet-wake structures among the blade passage outlets are also various. At the high static pressure zones of the volute, corresponding blade passage wake regions increase and their sizes are also influenced by the inlet distortion. The circumferential distributions of the static pressure in the diffuser agree well with that in the volute. In the diffuser, the non-uniform degrees of the static pressure distributions are roughly the same at different radius positions and are weakening with the decrease of the flow rate.

The Effect on Combustor Diffuser Performance of Structural OGV/Pre-Diffuser Systems

1997 ◽  
Author(s):  
A. G. Barker ◽  
J. F. Carrotte ◽  
C. W. Frodsham
Keyword(s):  
Static Pressure ◽  
Pressure Field ◽  
Guide Vane ◽  
Stagnation Pressure ◽  
Flame Tube ◽  
Flow Swirl ◽  
Pressure Distributions ◽  
Upstream Pressure ◽  
Inlet Conditions ◽  
The Impact

An experimental investigation has been carried out to assess the aerodynamic effects of locating radial struts within the pre-diffuser of a modern combustor dump diffuser system. Engine representative inlet conditions were generated by a single stage rotor, with the diffuser system incorporating various compressor outlet guide vane (OGV)/pre-diffuser assemblies and an annular flame tube with representative porosity. Stagnation and static pressure measurements were obtained at numerous locations and included assessment of the upstream pressure field, associated with the struts, which impacts on the rotor and OGV aerodynamics. Measurements were also obtained within the feed annuli, surrounding the flame tube, with attempts also being made to assess the stagnation pressure distributions presented to a simulated flame tube burner. Initial tests were performed with an OGV row attached to a conventional 1.45 area ratio pre-diffuser, this providing the datum to which all other systems were assessed. These included systems with thin or thick struts with the strut blockage, at pre-diffuser exit, being 5% and 11% of the gas passage area respectively. For the geometries tested it was shown that the method of adjusting each pre-diffuser passage area, to account for the strut blockage, was successful in providing similar levels of reduced kinetic energy at pre-diffuser exit. Despite this, however, the presence of strut wakes and their effect on the dump cavity flow produced increases in stagnation pressure loss. These loss variations were evaluated for both the feed annuli and burner flows, with the magnitudes depending on whether the struts were aligned or midway between burners. Also assessed was the impact of the increased circumferential flow non-uniformity that was observed for the flow within the inner feed annulus. A beneficial effect produced by the struts was the significant reductions in flow swirl, within the diffuser system, relative to the datum. This improved axial alignment of the flow, provided a more uniform pressure distribution to the burners and a more stable feed to the various flame tube features.

scholarly journals Experimental and Numerical Flow Analysis of an Engine-Realistic State-of-the-Art Turbine Rear Structure

2021 ◽  
Author(s):  
Valentin Vikhorev ◽  
Pär Nylander ◽  
Valery Chernoray ◽  
Jonas Larsson ◽  
Oskar Thulin
Keyword(s):  
Static Pressure ◽  
State Of The Art ◽  
Flow Analysis ◽  
Surface Flow ◽  
Secondary Flows ◽  
Test Facility ◽  
Turbofan Engine ◽  
Pressure Distributions ◽  
Outlet Flow ◽  
Engine Mount

Abstract This paper presents experimental and numerical CFD studies of the aerodynamics of a turbine rear structure (TRS). The TRS test geometry is an engine-realistic state-of-the-art design with a polygonal outer case, recessed engine mount bumps, and three different vane types: regular vanes, bump vanes in bump sectors, and thick vanes. Using three different sector types simultaneously was found to be crucial for the inlet boundary conditions. Experiments were performed in a modern rotating test facility with an LPT stage upstream of the TRS. A Reynolds number of 350,000 was used, representative of a TRS in a narrow-body geared turbofan engine. The TRS performance was analyzed both at on- and off-design conditions and a thorough side-by-side comparison of CFD and experiments was performed. Static-pressure-distributions, turning and outlet flow-angles, wakes and losses, and surface-flow visualizations and outlet total pressure contours are presented. The thick vane showed good aerodynamic performance, similar to the regular vane. For the bump vane, the mount bumps were found to generate additional local separations and secondary flows, resulting in extra losses. In the regions with strong secondary flows CFD over-predicts the wakes, whereas the wakes around midspan, where secondary flows have a smaller influence, are predicted well.

Regulating Effect of Asymmetrical Impeller on the Flow Distributions of Double-sided Centrifugal Compressor

2016 ◽  
Vol 0 (0) ◽  
Author(s):  
Ce Yang ◽  
Yixiong Liu ◽  
Dengfeng Yang ◽  
Benjiang Wang
Keyword(s):  
Flow Field ◽  
Centrifugal Compressor ◽  
Static Pressure ◽  
Mode Conversion ◽  
Work Capacity ◽  
Conversion Process ◽  
Impeller Blade ◽  
Pressure Distributions ◽  
Conversion Mode ◽  
Outlet Flow

AbstractTo achieve the rebalance of flow distributions of double-sided impellers, a method of improving the radius of rear impeller is presented in this paper. It is found that the flow distributions of front and rear impeller can be adjusted effectively by increasing the radius of rear impeller, thus improves the balance of flow distributions of front and rear impeller. Meanwhile, the working conversion mode process of double-sided centrifugal compressor is also changed. Further analysis shows that the flowrates of blade channels in front impeller are mainly influenced by the circumferential distributions of static pressure in the volute. But the flowrates of rear impeller blade channels are influenced by the outlet flow field of bent duct besides the effects of static pressure distributions in the volute. In the airflow interaction area downstream, the flowrate of blade channel is obviously smaller. By increasing the radius of rear impeller, the work capacity of rear impeller is enhanced, the working mode conversion process from parallel working mode of double-sided impeller to the single impeller working mode is delayed, and the stable working range of double-sided compressor is broadened.

Mean velocity and static pressure distributions of a circular jet

AIAA Journal ◽  
1997 ◽  
Vol 35 ◽  
pp. 196-197
Author(s):  
M. T. Islam ◽  
M. A. T. Ali
Keyword(s):  
Static Pressure ◽  
Mean Velocity ◽  
Pressure Distributions

scholarly journals Dynamic flight load measurements with MEMS pressure sensors

2021 ◽  
Author(s):  
Christian Raab ◽  
Kai Rohde-Brandenburger
Keyword(s):  
Pressure Distribution ◽  
Pressure Sensors ◽  
Flow Characteristics ◽  
Flight Test ◽  
Measurement Technology ◽  
Test Program ◽  
Aerodynamic Pressure ◽  
Pressure Distributions ◽  
Time Histories ◽  
Mems Pressure Sensors

AbstractThe determination of structural loads plays an important role in the certification process of new aircraft. Strain gauges are usually used to measure and monitor the structural loads encountered during the flight test program. However, a time-consuming wiring and calibration process is required to determine the forces and moments from the measured strains. Sensors based on MEMS provide an alternative way to determine loads from the measured aerodynamic pressure distribution around the structural component. Flight tests were performed with a research glider aircraft to investigate the flight loads determined with the strain based and the pressure based measurement technology. A wing glove equipped with 64 MEMS pressure sensors was developed for measuring the pressure distribution around a selected wing section. The wing shear force determined with both load determination methods were compared to each other. Several flight maneuvers with varying loads were performed during the flight test program. This paper concentrates on the evaluation of dynamic flight maneuvers including Stalls and Pull-Up Push-Over maneuvers. The effects of changes in the aerodynamic flow characteristics during the maneuver could be detected directly with the pressure sensors based on MEMS. Time histories of the measured pressure distributions and the wing shear forces are presented and discussed.

Experimental and Computational Analyses of Pressure Differentials in Flexible Ducts With Different Bent Angles

2007 ◽  
Author(s):  
Ray R. Taghavi ◽  
Wonjin Jin ◽  
Mario A. Medina
Keyword(s):  
Pressure Drop ◽  
Static Pressure ◽  
Complex Geometry ◽  
Analysis Data ◽  
Secondary Flows ◽  
Low Flow ◽  
Pressure Drops ◽  
Pressure Distributions ◽  
Geometrical Effects ◽  
Cfd Analyses

A set of experimental analyses was conducted to determine static pressure drops inside non-metallic flexible, spiral wire helix core ducts, with different bent angles. In addition, Computational Fluid Dynamics (CFD) solutions were performed and verified by comparing them to the experimental data. The CFD computations were carried out to produce more systematic pressure drop information through these complex-geometry ducts. The experimental setup was constructed according to ASHRAE Standard 120-1999. Five different bent angles (0, 30, 45, 60, and 90 degrees) were tested at relatively low flow rates (11 to 89 CFM). Also, two different bent radii and duct lengths were tested to study flexible duct geometrical effects on static pressure drops. FLUENT 6.2, using RANS based two equations - RNG k-ε model, was used for the CFD analyses. The experimental and CFD results showed that larger bent angles produced larger static pressure drops in the flexible ducts. CFD analysis data were found to be in relatively good agreement with the experimental results for all bent angle cases. However, the deviations became slightly larger at higher velocity regimes and at the longer test sections. Overall, static pressure drop for longer length cases were approximately 0.01in.H2O higher when compared to shorter cases because of the increase in resistance to the flow. Also, the CFD simulations captured more pronounced static pressure drops that were produced along the sharper turns. The stronger secondary flows, which resulted from higher and lower static pressure distributions in the outer and inner surfaces, respectively, contributed to these higher pressure drops.

scholarly journals Computational Modeling of Flow Characteristics in Three Products Hydrocyclone Screen

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1295
Author(s):  
Anghong Yu ◽  
Chuanzhen Wang ◽  
Haizeng Liu ◽  
Md. Shakhaoath Khan
Keyword(s):  
Static Pressure ◽  
Cfd Simulation ◽  
Volume Fraction ◽  
Flow Characteristics ◽  
Pressure Profile ◽  
Reynolds Stress Model ◽  
Grid Scheme ◽  
Cylindrical Screen ◽  
The Right ◽  
Axial Depth

Three products hydrocyclone screen (TPHS) can be considered as the combination of a conventional hydrocyclone and a cylindrical screen. In this device, particles are separated based on size under the centrifugal classification coupling screening effect. The objective of this work is to explore the characteristics of fluid flow in TPHS using the computational fluid dynamics (CFD) simulation. The 2 million grid scheme, volume fraction model, and linear pressure–strain Reynolds stress model were utilized to generate the economical grid-independence solution. The pressure profile reveals that the distribution of static pressure was axisymmetric, and its value was reduced with the increasing axial depth. The maximum and minimum were located near the tangential inflection point of the feed inlet and the outlets, respectively. However, local asymmetry was created by the left tangential inlet and the right screen underflow outlet. Furthermore, at the same axial height, the static pressure gradually decreased along the wall to the center. Near the cylindrical screen, the pressure difference between the inside and the outside cylindrical screen dropped from positive to negative as the axial depth increased from −35 to −185 mm. Besides, TPHS shows similar distributions of turbulence intensity I, turbulence kinetic energy k, and turbulence dissipation rate ε; i.e., the values fell with the decrease in axial height. Meanwhile, from high to low, the pressure values are distributed in the feed chamber, the cylindrical screen, and conical vessel; the value inside the screen was higher than the outer value.

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