Compressor Drum Aerodynamic Experiments and Analysis With Coolant Injected at Selected Locations

1991 ◽  
Vol 113 (2) ◽  
pp. 272-280 ◽  
Author(s):  
B. V. Johnson ◽  
W. A. Daniels ◽  
E. J. Kawecki ◽  
R. J. Martin
Keyword(s):  
Turbulent Viscosity ◽  
Tangential Velocity ◽  
Flow Characteristics ◽  
Aircraft Engine ◽  
Reynolds Numbers ◽  
Coolant Flow ◽  
Pressure Distributions ◽  
Coolant Injection ◽  
High Pressure Compressor ◽  
Momentum Integral

Experiments were conducted to determine the pressure distributions within a multicavity compressor drum model for two coolant injection locations and a range of flow conditions. Flow was injected through the upstream conical wall or through the cylindrical wall of the rotating model. The coolant flow, the drum rotational rate, and the model pressure were varied to produce a range of tangential and coolant flow Reynolds numbers, typical of large aircraft engine high-pressure compressor drums. The experimental results were used to evaluate analytical procedures for predicting flow characteristics in rotating annular cavities with radially inward flow and for correlating flow characteristics in multiple-rotating annular cavities, which are not currently predicted. Swirling flows, radially inward between compressor disks and within rotating annular cavities with no net flow, were analyzed with a procedure that coupled a viscous solution for the rotating core flow with a momentum integral analysis for the boundary layers on the disks. Constant viscosity and variable turbulent viscosity models were used in the analysis. Results from the analysis and the experiments were used to estimate the tangential velocity distribution in trapped cavities for two coolant injection configurations and a range of flow rates.

scholarly journals Compressor Drum Aerodynamic Experiments and Analysis With Coolant Injected at Selected Locations

1990 ◽  
Author(s):  
B. V. Johnson ◽  
W. A. Daniels ◽  
E. J. Kawecki ◽  
R. J. Martin
Keyword(s):  
Turbulent Viscosity ◽  
Tangential Velocity ◽  
Flow Characteristics ◽  
Aircraft Engine ◽  
Reynolds Numbers ◽  
Coolant Flow ◽  
Pressure Distributions ◽  
Coolant Injection ◽  
High Pressure Compressor ◽  
Momentum Integral

Experiments were conducted to determine the pressure distributions within a multi–cavity compressor drum model for two coolant injection locations and a range of flow conditions. Flow was injected through the upstream conical wall or through the cylindrical wall of the rotating model. The coolant flow, the drum rotational rate, and the model pressure were varied to produce a range of tangential and coolant flow Reynolds numbers, typical of large aircraft engine high pressure compressor drums. The experimental results were used to evaluate analytical procedures for predicting flow characteristics in rotating annular cavities with radially inward flow and for correlating flow characteristics in multiple–rotating annular cavities which are not currently predicted. Swirling flows, radially inward between compressor disks and within rotating annular cavities with no net flow, were analyzed with a procedure which coupled a viscous solution for the rotating core flow with a momentum integral analysis for the boundary layers on the disks. Constant viscosity and variable turbulent viscosity models were used in the analysis. Results from the analysis and the experiments were used to estimate the tangential velocity distribution in trapped cavities for two coolant injection configurations and a range of flow rates.

The Departure from Equilibrium of Turbulent Boundary Layers

1968 ◽  
Vol 19 (1) ◽  
pp. 1-19 ◽  
Author(s):  
H. McDonald
Keyword(s):  
Boundary Layer ◽  
Shear Stress ◽  
Kinetic Energy ◽  
Stress Distribution ◽  
Boundary Layers ◽  
Turbulent Boundary Layers ◽  
Two Dimensional ◽  
Pressure Distributions ◽  
Momentum Integral ◽  
State Examination

SummaryRecently two authors, Nash and Goldberg, have suggested, intuitively, that the rate at which the shear stress distribution in an incompressible, two-dimensional, turbulent boundary layer would return to its equilibrium value is directly proportional to the extent of the departure from the equilibrium state. Examination of the behaviour of the integral properties of the boundary layer supports this hypothesis. In the present paper a relationship similar to the suggestion of Nash and Goldberg is derived from the local balance of the kinetic energy of the turbulence. Coupling this simple derived relationship to the boundary layer momentum and moment-of-momentum integral equations results in quite accurate predictions of the behaviour of non-equilibrium turbulent boundary layers in arbitrary adverse (given) 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 Investigation of Effect of Tip Coolant Ejection on Internal Flow Characteristics Within a Realistic Blade Coolant Channel

2013 ◽  
Author(s):  
Jian Pu ◽  
Zhaoqing Ke ◽  
Jianhua Wang ◽  
Lei Wang ◽  
Hongde You
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Turbine Blade ◽  
Flow Rate ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Flow Ratio ◽  
Lp Turbine ◽  
Mass Flow Ratio

This paper presents an experimental investigation on the characteristics of the fluid flow within an entire coolant channel of a low pressure (LP) turbine blade. The serpentine channel, which keeps realistic blade geometry, consists of three passes connected by a 180° sharp bend and a semi-round bend, 2 tip exits and 25 trailing edge exits. The mean velocity fields within several typical cross sections were captured using a particle image velocimetry (PIV) system. Pressure and flow rate at each exit were determined through the measurements of local static pressure and volume flow rate. To optimize the design of LP turbine blade coolant channels, the effect of tip ejection ratio (ER) from 180° sharp bend on the flow characteristics in the coolant channel were experimentally investigated at a series of inlet Reynolds numbers from 25,000 to 50,000. A complex flow pattern, which is different from the previous investigations conducted by a simplified square or rectangular two-pass U-channel, is exhibited from the PIV results. This experimental investigation indicated that: a) in the main flow direction, the regions of separation bubble and flow impingement increase in size with a decrease of the ER; b) the shape, intensity and position of the secondary vortices are changed by the ER; c) the mass flow ratio of each exit to inlet is not sensitive to the inlet Reynolds number; d) the increase of the ER reduces the mass flow ratio through each trailing edge exit to the extent of about 23–28% of the ER = 0 reference under the condition that the tip exit located at 180° bend is full open; e) the pressure drop through the entire coolant channel decreases with an increase in the ER and inlet Reynolds number, and a reduction about 35–40% of the non-dimensional pressure drop is observed at different inlet Reynolds numbers, under the condition that the tip exit located at 180° bend is full open.

Numerical Simulation for Flow over Two Circular Cylinders in Micro Channel with Lattice Boltzmann Method

2014 ◽  
Vol 670-671 ◽  
pp. 747-750
Author(s):  
Zhi Jun Gong ◽  
Jiao Yang ◽  
Wen Fei Wu
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Recirculation Zone ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Circular Cylinders ◽  
Micro Channel ◽  
Zone Length ◽  
Spacing Ratio ◽  
Boltzmann Method

For indepth study on flow characteristics for fluid bypass obstacles in micro-channel, the Lattice Boltzmann Method (LBM) was used to simulate fluid flow over two circular cylinders in side-by-side arrangement of a micro-channel. The velocity distribution and recirculation zone length under different Reynolds numbers (Re = 0~100) and different spacing ratio (H/D= 0~2.0) were obtained. The results show that the pattern of flow and the size of recirculation zone in the micro-channel depend on the combined effect of Re and H/D.

A particle image velocimetry study on the pulsatile flow characteristics in straight tubes with an asymmetric bulge

2000 ◽  
Vol 214 (5) ◽  
pp. 655-671 ◽  
Author(s):  
S C M Yu ◽  
J B Zhao
Keyword(s):  
Particle Image Velocimetry ◽  
Steady Flow ◽  
Pulsatile Flow ◽  
Flow Condition ◽  
Particle Image ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Working Fluid ◽  
Flow Conditions ◽  
Image Velocimetry

Flow characteristics in straight tubes with an asymmetric bulge have been investigated using particle image velocimetry (PIV) over a range of Reynolds numbers from 600 to 1200 and at a Womersley number of 22. A mixture of glycerine and water (approximately 40:60 by volume) was used as the working fluid. The study was carried out because of their relevance in some aspects of physiological flows, such as arterial flow through a sidewall aneurysm. Results for both steady and pulsatile flow conditions were obtained. It was found that at a steady flow condition, a weak recirculating vortex formed inside the bulge. The recirculation became stronger at higher Reynolds numbers but weaker at larger bulge sizes. The centre of the vortex was located close to the distal neck. At pulsatile flow conditions, the vortex appeared and disappeared at different phases of the cycle, and the sequence was only punctuated by strong forward flow behaviour (near the peak flow condition). In particular, strong flow interactions between the parent tube and the bulge were observed during the deceleration phase. Stents and springs were used to dampen the flow movement inside the bulge. It was found that the recirculation vortex could be eliminated completely in steady flow conditions using both devices. However, under pulsatile flow conditions, flow velocities inside the bulge could not be suppressed completely by both devices, but could be reduced by more than 80 per cent.

An Investigation of Flow Characteristics and Parameter Effects for a New Concept of Hybrid SVC Nozzle

2018 ◽  
Author(s):  
F. Song ◽  
J. W. Shi ◽  
L. Zhou ◽  
Z. X. Wang ◽  
X. B. Zhang
Keyword(s):  
Static Pressure ◽  
Pressure Ratio ◽  
Flow Characteristics ◽  
Exhaust System ◽  
Aircraft Engine ◽  
Thrust Coefficient ◽  
Thrust Vectoring ◽  
Static Pressure Distribution ◽  
Thrust Vector ◽  
Vector Angle

Lighter weight, simpler structure, higher vectoring efficiency and faster vector response are recent trends in development of aircraft engine exhaust system. To meet these new challenges, a concept of hybrid SVC nozzle was proposed in this work to achieve thrust vectoring by adopting a rotatable valve and by introducing a secondary flow injection. In this paper, we numerically investigated the flow mechanism of the hybrid SVC nozzle. Nozzle performance (e.g. the thrust vector angle and the thrust coefficient) was studied with consideration of the influence of aerodynamic and geometric parameters, such as the nozzle pressure ratio (NPR), the secondary pressure ratio (SPR) and the deflection angle of the rotatable valve (θ). The numerical results indicate that the introductions of the rotatable valve and the secondary injection induce an asymmetrically distributed static pressure to nozzle internal walls. Such static pressure distribution generates a side force on the primary flow, thereby achieving thrust vectoring. Both the thrust vector angle and vectoring efficiency can be enhanced by reducing NPR or by increasing θ. A maximum vector angle of 16.7 ° is attained while NPR is 3 and the corresponding vectoring efficiency is 6.33 °/%. The vector angle first increases and then decreases along with the elevation of SPR, and there exists an optimum value of SPR for maximum thrust vector angle. The effects of θ and SPR on the thrust coefficient were found to be insignificant. The rotatable valve can be utilized to improve vectoring efficiency and to control the vector angle as expected.

Experimental Analysis of a NACA 0021 Airfoil Under Dynamic Angle of Attack Variation and Low Reynolds Numbers

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
D. Holst ◽  
B. Church ◽  
F. Wegner ◽  
G. Pechlivanoglou ◽  
C. N. Nayeri ◽  
...  
Keyword(s):  
Design Process ◽  
Surface Pressure ◽  
Wind Turbines ◽  
Full Range ◽  
Vertical Axis ◽  
Reynolds Numbers ◽  
Time Resolved ◽  
Pressure Distributions ◽  
Pressure Development ◽  
Flow Phenomena

The wind industry needs reliable and accurate airfoil polars to properly predict wind turbine performance, especially during the initial design phase. Medium- and low-fidelity simulations directly depend on the accuracy of the airfoil data and even more so if, e.g., dynamic effects are modeled. This becomes crucial if the blades of a turbine operate under stalled conditions for a significant part of the turbine's lifetime. In addition, the design process of vertical axis wind turbines needs data across the full range of angles of attack between 0 and 180 deg. Lift, drag, and surface pressure distributions of a NACA 0021 airfoil equipped with surface pressure taps were investigated based on time-resolved pressure measurements. The present study discusses full range static polars and several dynamic sinusoidal pitching configurations covering two Reynolds numbers Re = 140k and 180k, and different incidence ranges: near stall, poststall, and deep stall. Various bistable flow phenomena are discussed based on high frequency measurements revealing large lift-fluctuations in the post and deep stall regime that exceed the maximum lift of the static polars and are not captured by averaged measurements. Detailed surface pressure distributions are discussed to provide further insight into the flow conditions and pressure development during dynamic motion. The experimental data provided within the present paper are dedicated to the scientific community for calibration and reference purposes, which in the future may lead to higher accuracy in performance predictions during the design process of wind turbines.

Surface Pressure Distribution on a Blade of a 10 m Diameter HAWT (Field Measurements versus Wind Tunnel Measurements)

2005 ◽  
Vol 127 (2) ◽  
pp. 185-191 ◽  
Author(s):  
T. Maeda ◽  
E. Ismaili ◽  
H. Kawabuchi ◽  
Y. Kamada
Keyword(s):  
Wind Tunnel ◽  
Surface Pressure ◽  
Field Measurements ◽  
Reynolds Numbers ◽  
Blade Surface ◽  
Pressure Data ◽  
Surface Pressure Distribution ◽  
Pressure Distributions ◽  
Wind Tunnel Data ◽  
Local Angle

This paper exploits blade surface pressure data acquired by testing a three-bladed upwind turbine operating in the field. Data were collected for a rotor blade at spanwise 0.7R with the rotor disc at zero yaw. Then, for the same blade, surface pressure data were acquired by testing in a wind tunnel. Analyses compared aerodynamic forces and surface pressure distributions under field conditions against analogous baseline data acquired from the wind tunnel data. The results show that aerodynamic performance of the section 70%, for local angle of attack below static stall, is similar for free stream and wind tunnel conditions and resemblances those commonly observed on two-dimensional aerofoils near stall. For post-stall flow, it is presumed that the exhibited differences are attributes of the differences on the Reynolds numbers at which the experiments were conducted.

scholarly journals Influence of twisted tape insert on the coolant flow characteristics in swirled film cooling

2021 ◽  
pp. 259-259
Author(s):  
Vashista Ademane ◽  
Ravikiran Kadoli ◽  
Vijaykumar Hindasageri
Keyword(s):  
Film Cooling ◽  
Flow Characteristics ◽  
Coolant Flow ◽  
Twisted Tape ◽  
Pumping Power ◽  
Pressure Losses ◽  
Jet Trajectory ◽  
Swirl Intensity ◽  
Cooling Behavior ◽  
Coefficient Of Discharge

The Present paper discusses film cooling behavior through numerical simulation in the presence of a twisted tape insert inside the film hole. The twisted tape insert imparts a swirl to the coolant flow. Coolant swirl intensity is controlled by varying the pitch of the twisted tape resulting in swirl numbers (S) of 0.0289, 0.116 and 0.168. The film cooling performance is evaluated using area-averaged effectiveness and heat transfer coefficient for blowing ratios of 0.5, 1.0, 1.5 and 2.0. Results revealed a significant amount of improvement in averaged effectiveness with the addition of swirl. Coolant swirl predominantly modifies the jet trajectory resulting in a reduced jet penetration and increased lateral expansion. Further investigation on the effect of twisted tape thickness on the coolant distribution has been found to be negligible. Pressure losses occurring due to the insertion of twisted tape inside the film hole is evaluated through the coefficient of discharge which indicated the necessity of higher pumping power than the film cooling case with no-swirl.

Sign in / Sign up

Export Citation Format

Share Document