scholarly journals Experimental Investigations of Supersonic Cascades Designed for High Static Pressure Ratios

1977 ◽  
Author(s):  
R. Fuchs ◽  
H. Starken
Keyword(s):  
Total Pressure ◽  
Static Pressure ◽  
Research Work ◽  
Axial Direction ◽  
Experimental Investigations ◽  
Blade Row ◽  
Stator Blade ◽  
High Static Pressure ◽  
Inlet Conditions ◽  
Very High

The outlet conditions of supersonic compressor rotors designed for very high total pressure ratios can be highly supersonic (impulse rotors). Then the following stator blade row has to build up high static pressure ratios at supersonic inlet conditions. This paper describes part of a research work which should answer, if it is at all possible to realize such high static pressure ratios in a cascade. Cascades with convergent-divergent blade passages were designed and optimized by boundary layer calculations. In a first step no flow turning was incorporated in the blade sections. A three-shock-type cascade was found to be an optimum design The wind tunnel measurements resulted in static pressure ratios of the order of 6 and total pressure ratios of 0.77 at inlet Mach numbers of 2.2. In a second step the flow turning to axial direction was realized. For that two types of cascades were built and tested. One was a tandem type cascade and the other a single row cascade. The experiments at inlet design conditions resulted in static pressure ratios of the order of 6.5 and total pressure ratios of 0.72.

Radial Variation in Distortion Transfer and Generation Through a Highly Loaded Fan Stage

2018 ◽  
Author(s):  
Daniel R. Soderquist ◽  
Steven E. Gorrell ◽  
Michael G. List
Keyword(s):  
Total Pressure ◽  
Aerodynamic Performance ◽  
Phase Shifts ◽  
Tip Clearance ◽  
Temperature Profiles ◽  
Radial Migration ◽  
Blade Row ◽  
Compressor Design ◽  
Stator Blade ◽  
Total Temperature

An important consideration for fan and compressor design is quantifying distortion transfer and generation blade row by blade row. Detailed information about the magnitude of distortion and the shape of the distortion profile and how it changes through blade rows increases the understanding of flow physics and helps predict aerodynamic performance. Using full annulus URANS simulations, this paper analyzes what happens to distortion as it passes through the rotor and stator blade rows at 10%, 30%, 50%, 70%, and 90% span. Fourier distortion descriptors are used in this study to quantitatively describe distortion transfer and generation. With these descriptors, evidence of pressure-induced swirl is shown at the fan inlet. It is also shown that although there is very little distortion at the 10% span of the inlet, after passing through the rotor blade row the 10% span has the greatest amount of total pressure and total temperature distortion. This radial migration of distortion is attributed to the high hade angle of the hub. The total pressure and total temperature profiles have significant circumferential phase shifts after passing through the rotor and slight phase shifts after passing through the stator. In general, the calculated phase shifts are greatest at the 10% and 90% spans, the nearest locations to the hub and the tip clearance gap, respectively.

Multiple Segment Parallel Compressor Model for Circumferential Flow Distortion

1977 ◽  
Vol 99 (2) ◽  
pp. 288-296 ◽  
Author(s):  
R. S. Mazzawy
Keyword(s):  
Compressible Flow ◽  
Large Amplitude ◽  
Total Pressure ◽  
Flow Model ◽  
Static Pressure ◽  
Accurate Approximation ◽  
Flow Distortion ◽  
Basic Model ◽  
Blade Row ◽  
Compressor Performance

A nonlinear compressible flow model has been developed for the prediction of compressor performance and stability with a circumferential flow distortion. This model uses multiple parallel compressor segments and accounts for deviations from undistorted compressor performance. It is applicable to large-amplitude inlet distortions of total pressure and/or temperature, as well as circumferential variations in exit static pressure. The basic model requires the undistorted performance characteristics for each blade row; however, a modified version based upon the overall compressor performance gives an accurate approximation when detailed blade row characteristics are not available.

Flow Measurements in a Fishtail Diffuser With Strong Curvature

1999 ◽  
Vol 121 (2) ◽  
pp. 410-417 ◽  
Author(s):  
M. I. Yaras
Keyword(s):  
Boundary Layer ◽  
Pressure Loss ◽  
Total Pressure ◽  
Static Pressure ◽  
Secondary Flows ◽  
Total Pressure Loss ◽  
Cross Sectional ◽  
Inlet Flow ◽  
Inlet Conditions ◽  
Strong Curvature

The paper presents detailed measurements of the incompressible flow development in a large-scale 90 deg curved diffuser with strong curvature and significant streamwise variation in cross-sectional aspect ratio. The flow path approximates the so-called fishtail diffuser utilized on small gas turbine engines for the transition between the centrifugal impeller and the combustion chamber. Two variations of the inlet flow, differing in boundary layer thickness and turbulence intensity, are considered. Measurements consist of three components of velocity, static pressure and total pressure distributions at several cross-sectional planes throughout the diffusing bend. The development and mutual interaction of multiple pairs of streamwise vortices, redistribution of the streamwise flow under the influence of these vortices, the resultant streamwise variations in mass-averaged total-pressure and static pressure, and the effect of inlet conditions on these aspects of the flow are examined. The strengths of the vortical structures are found to be sensitive to the inlet flow conditions, with the inlet flow comprising a thinner boundary layer and lower turbulence intensity yielding stronger secondary flows. For both inlet conditions a pair of streamwise vortices develop rapidly within the bend, reaching their peak strength at about 30 deg into the bend. The development of a second pair of vortices commences downstream of this location and continues for the remainder of the bend. Little evidence of the first vortex pair remains at the exit of the diffusing bend. The mass-averaged total pressure loss is found to be insensitive to the range of inlet-flow variations considered herein. However, the rate of generation of this loss along the length of the diffusing bend differs between the two test cases. For the case with the thinner inlet boundary layer, stronger secondary flows result in larger distortion of the streamwise velocity field. Consequently, the static pressure recovery is somewhat lower for this test case. The difference between the streamwise distributions of measured and ideal static pressure is found to be primarily due to total pressure loss in the case of the thick inlet boundary layer. For the thin inlet boundary layer case, however, total pressure loss and flow distortion are observed to influence the pressure recovery by comparable amounts.

scholarly journals Novel Characteristics of Subsonic Coflowing Jets With Varying Lip Thickness

2020 ◽  
Author(s):  
Naren Shankar Radha Krishnan ◽  
Dilip Raja Narayana
Keyword(s):  
Mach Number ◽  
Atmospheric Pressure ◽  
Total Pressure ◽  
Radial Direction ◽  
Static Pressure ◽  
Axial Direction ◽  
Pressure Variation ◽  
Geometrical Constraints ◽  
The Mean ◽  
Mach Numbers

Effect of Mach number on coflowing jet at lip thickness of 0.2 Dp, 1.0 Dp and 1.5 Dp (where Dp is primary nozzle exit diameter, 10 mm) at Mach numbers 1.0, 0.8 and 0.6 were studied experimentally. It was found that an increase in Mach number does not have any profound effect on axial total and static pressure variation for 0.2 Dp. Decreasing the mean diameter is due to the geometrical constraints. In this study, the primary nozzle dimension and secondary duct is maintained constant for comparison. For the case of 0.2 Dp, static pressure is almost equal to atmospheric pressure for all Mach numbers. Whereas for other two lip thickness, increase in Mach number marginally influences axial total pressure and profoundly varies static pressure. It is noted that it varies considerably up to 11.1% in the axial direction and up to 17% in the radial direction for Mach number 1.0. For lower Mach numbers, such variation is not observed. Increase in Mach number increases static pressure variation in the coflowing jet flow field with lip thickness 1.0 Dp and 1.5 Dp.

Design of a Highly-Loaded Four-Stage Low-Speed Research Compressor

2008 ◽  
Author(s):  
C. Clemen ◽  
H. Schrapp ◽  
V. Gu¨mmer ◽  
R. Mu¨ller ◽  
M. Ku¨nzelmann ◽  
...  
Keyword(s):  
Static Pressure ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Navier Stokes ◽  
Experimental Investigations ◽  
Flow Measurements ◽  
Low Speed ◽  
Pressure Surface ◽  
Overall Performance ◽  
Inlet Conditions

The present paper describes the design of a new set of blades for the four-stage axial-flow low-speed research compressor (LSRC) at the TU Dresden. The compressor contains nine blade rows: IGV, four rotors and four cantilevered stators designed as repeating stages. The compressor was originally designed and built in the German AG Turbo project. In recent years fourteen builds of the compressor were built and tested [1]. The new design of the NGV (Build A15) has increased pressure ratio and loading compared to the previous builds. The design was performed using a method giving three-dimensionally optimised blades achieving better efficiency than the previous builds with sufficient operating range despite increased loading. The numerical analysis was carried out using a Rolls-Royce 3D-Navier-Stokes solver at design and off-design inlet conditions. The experimental investigations were carried out by the Technical University of Dresden. Overall performance was measured for different speeds and different back-pressures up to compressor stall. Flow field details were measured at a design and a close-to-stall condition using static pressure probes on the blade suction and pressure surface and secondary flow measurements using 5-hole probes.

scholarly journals Theoretical and Experimental Investigation of Circumferential Grooved Casing/Hub Treatment

1994 ◽  
Author(s):  
Zhaohui Du ◽  
Zhiwei Liu
Keyword(s):  
Axial Flow ◽  
Single Stage ◽  
Experimental Investigations ◽  
Operation Condition ◽  
Stall Margin ◽  
3 Dimensional ◽  
Blade Row ◽  
Stator Blade ◽  
Flow Compressor ◽  
Theoretical Analyses

In this paper the 3-dimensional viscous numerical calculation is applied to explain the mechanism of extending stability of circumferential grooved casing and hub treatments. A new index which can quantitatively evaluate the ability to extend stability of circumferential grooved casing and hub treatments is proposed with flux of gas through the treatment grooves. The influences of the geometric parameters on improving stall margin are discussed. The conclusions are the same as those of experiments. A circumferential grooved hub treatment is designed and tested beneath the stator blade row in a single stage axial flow compressor. The upstream and downstream 3-dimension flowfields are measured carefully in optimum operation condition and near stall margin condition by a combined three-hole probe and a mirco-five-hole probe which has 1.5mm diameter. It is shown that stall margin can be improved not only for the single stage compressor, but also for the rotor. Through a lot of experimental investigations and theoretical analyses, the mechanism of extending stability of circumferential grooved casing and hub treatments are systematic and comprehensive explained.

Experimental and numerical investigation of expansion corner effects on isolator performance

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Jaimon D. Quadros ◽  
Sher Afghan Khan ◽  
T. Prashanth
Keyword(s):  
Nozzle Exit ◽  
Static Pressure ◽  
Pressure Rise ◽  
Experimental Investigations ◽  
Shock Train ◽  
Flow Process ◽  
Cross Sectional ◽  
Static Pressure Distribution ◽  
Pitot Pressure ◽  
High Static Pressure

AbstractIn the present study, the effect of expansion corner on suddenly expanded flow process has been studied. Experimental investigations have been carried out on a convergent-divergent (C-D) nozzle and isolator duct, where the expansion of the channel is formed through the presence of a 1, 2 and 3 expansion corners (EC) respectively. Flow from nozzle exit of the nozzle of Mach, M = 2.0 was suddenly expanded into the axi-symmetric duct having a cross sectional area of 4.84 times the nozzle exit area. The wall static pressure along the length of the duct and the Pitot pressure at the exit plane of the duct were measured for all the configurations. Computational fluid dynamics (CFD) technique was employed for visualizing the shock-train in the expanded duct. The isolator with one expansion corner was found to be more efficient in achieving a high static pressure rise. The experimental and numerical wall static pressure distribution values were compared for isolators with EC = 2 and found to be in good agreement with each other with a maximum absolute percentage deviation of 11%.

Numerical Investigation of Dump Diffuser Combustor Performance at Uniform and Non-Uniform Inlet Conditions

2020 ◽  
Author(s):  
Heyu Wang ◽  
Kai Hong Luo
Keyword(s):  
Boundary Layer ◽  
Numerical Investigation ◽  
Layer Thickness ◽  
Pressure Loss ◽  
Total Pressure ◽  
Boundary Layer Thickness ◽  
Static Pressure ◽  
Aerodynamic Performance ◽  
Aero Engine ◽  
Inlet Conditions

Abstract A numerical investigation has been conducted for an axisymmetric dump diffuser combustor, which is a simplified geometry of a typical lean-burn combustor in a modern civil aero-engine gas turbine. The aerodynamic performance of the combustor is analyzed with an emphasis on two common performance parameters: static pressure recovery and total pressure loss. The former is essential in maintaining high-pressure air flow across the liner, whereas the latter involves the specific fuel consumption of the aero-engine. At first, the effects of geometrical parameters of the dump diffuser combustor are investigated. A high diffuser angle seems to be detrimental to both static pressure recovery and total pressure loss. On the other hand, a high dump gap ratio is beneficial from the aerodynamic performance point of view. However, all these desired characteristics are subject to mechanical constraints and their implications for specific consumption. Optimum values of those parameters should exist for a given desired aerodynamics performance. The majority of previous researches, including the first part of this study, have been carried out with uniform inlet conditions due to a typical independent design cycle of each component. The effects of compressor exit conditions are usually not considered in the early stage design process. In the second part of this study, various inlet conditions representing a more realistic compressor exit condition such as inlet symmetrical and asymmetrical boundary layer thickness are investigated. The performance of an asymmetrical configuration with a thin boundary layer thickness near the outer annulus is almost comparable to that of its uniform counterpart. Findings of this study provide useful input for combustor designers to improve the combustor’s performance based on the compressor exit conditions.

scholarly journals Numerical Investigation of flow through Annular diffusing duct

2011 ◽  
pp. 60-63
Author(s):  
Prasanta K. Sinha ◽  
Ananta Kumar Das ◽  
Bireswar Majumdar
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Static Pressure ◽  
Line Length ◽  
Area Ratio ◽  
Experimental Results ◽  
Total Pressure Loss ◽  
Pressure Recovery ◽  
Mean Velocity ◽  
Inlet Conditions

In the present investigation the distribution of mean velocity, static pressure and total pressure are experimentally studied on an annular curved diffuser of 30° angle of turn with an area ratio of 1.283 and centerline length was chosen as three times of inlet diameter. The experimental results then were numerically validated with the help of Fluent and then a series of parametric investigations are conducted with same centre line length and inlet diameter but with different area ratios varying from 1.15 to 3.75. The measurements were taken at Reynolds number 2.25 x 105 based on inlet diameter and mass average inlet velocity. Predicted results of coefficient of mass averaged static pressure recovery (30%) and coefficient of mass averaged total pressure loss (21%) are in good agreement with the experimental results of coefficient of mass averaged static pressure recovery (26%) and coefficient of mass averaged total pressure loss (17%) respectively. Standard k-ε model in Fluent solver was chosen for validation. From the parametric investigation it is observed that static pressure recovery increases up to an area ratio of 2.86 and between the area ration 2.86 to 3.75, pressure recovery decreases steadily. The coefficient of total pressure loss almost remains constant with the change in area ratio for similar inlet conditions.

Inlet Boundary Layer Effects in an Axial Compressor Rotor: Part II—Throughflow Effects

1985 ◽  
Vol 107 (2) ◽  
pp. 381-386 ◽  
Author(s):  
J. H. Wagner ◽  
R. P. Dring ◽  
H. D. Joslyn
Keyword(s):  
Boundary Layer ◽  
Total Pressure ◽  
Static Pressure ◽  
Pressure Field ◽  
Axial Compressor ◽  
Frame Of Reference ◽  
Tip Leakage ◽  
Compressor Rotor ◽  
Blade Row ◽  
Major Loss

This paper presents results of an experimental aerodynamic study conducted in the rotating frame of reference downstream of an isolated compressor rotor with both thick and thin inlet endwall boundary layers. The paper focuses on those aspects of the data having particular significance to the assumptions and application of throughflow theory. These aspects include the spanwise distributions of static pressure and blockage, and the radial redistribution of fluid as it passes through the blade row. It is demonstrated that the main contributions to total pressure loss, blockage, and the distortion of the static pressure field were due to the hub corner stall and tip leakage. This is a significant departure from previous conclusions which looked to the endwall boundary layer and to secondary flow as major loss and blockage producing mechanisms.

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