scholarly journals Discussion: “Influence of Inlet Flow Conditions and Geometries of Centrifugal Vaneless Diffusers on Critical Flow Angle for Reverse Flow” (Senoo, Yasutoshi, and Kinoshita, Yoshifumi, 1977, ASME J. Fluids Eng., 99, pp. 98–102)

1977 ◽  
Vol 99 (1) ◽  
pp. 102-102
Author(s):  
C. Rodgers
Keyword(s):  
Reverse Flow ◽  
Critical Flow ◽  
Flow Conditions ◽  
Inlet Flow ◽  
Flow Angle ◽  
Vaneless Diffusers

Influence of Inlet Flow Conditions and Geometries of Centrifugal Vaneless Diffusers on Critical Flow Angle for Reverse Flow

1977 ◽  
Vol 99 (1) ◽  
pp. 98-102 ◽  
Author(s):  
Yasutoshi Senoo ◽  
Yoshifumi Kinoshita
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Boundary Layer Thickness ◽  
Reverse Flow ◽  
Critical Flow ◽  
Flow Conditions ◽  
Flow Angle ◽  
Inlet Velocity ◽  
Vaneless Diffusers ◽  
Inlet Conditions

The authors’ preceding analysis on centrifugal vaneless diffusers is used to examine the influences of diffuser geometries and of flow inlet conditions on the critical flow angle for reverse flow, and the results are presented in graphs. The diffuser width to radius ratio, the inlet Mach number, and the distortion of the inlet velocity distribution have significant influences on the critical flow angle, while the Reynolds number and the boundary layer thickness at the inlet have minor influences.

Experimental Investigation of Gas Turbine Axial Diffuser Performance: Part II — Effect of Inlet Flow Profiles at On- and Off-Design Conditions

2021 ◽  
Author(s):  
Kenneth Brown ◽  
Stephen Guillot ◽  
Wing Ng ◽  
Lee Iksang ◽  
Kim Dongil ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Flow Visualization ◽  
Gas Turbines ◽  
Full Scale ◽  
Flow Conditions ◽  
Inlet Flow ◽  
Flow Angle ◽  
Companion Article ◽  
Pressure Distributions ◽  
Physical Insight

Abstract An experimental investigation of the effect of inlet flow conditions and improved geometries on the performance of modern axial exhaust diffusers of gas turbines has been completed. The first article in the two-part series [1] leveraged a scaled model to examine parametric variations in both diffuser geometry and inlet flow conditions with the latter having significant consequences for diffuser performance. This second article pivots on the conclusions of the companion article and offers findings and physical insight on diffuser performance for on- and off-design inlet flow conditions. Using a high-performing diffuser design from the companion article, an experimental investigation is carried out with tailored distributions of inlet Mach distribution, inlet swirl angle, and inlet radial flow angle which are designed to replicate conditions of an industry diffuser at various loads. Six different inlet distributions were investigated including a design condition and five other conditions which feature mass flows both greater than and less than the design condition. The measurements were taken at near full-scale turbine exit Reynolds number (ReH roughly 39% of the value for an H-class diffuser) and at full-scale turbine exit Mach number. The study was accomplished in a blow-down, cold-flow wind tunnel facility, and measurements included 5-hole probe traverses at planes of interest, axial pressure distributions, strut pressure distributions, and oil-flow visualization. Over the range of inlet conditions studied, pressure recovery at the exit varied by up to 68.5% from that of on-design operation. Tracking of performance coefficients along the axial direction suggested the existence of flow phenomena which were in some cases able to be confirmed with on-strut pressure measurements and flow visualization. In addition to physical insight, the results presented here offer an experimental benchmark for the sensitivity of diffuser performance to inlet flow conditions.

scholarly journals Mathematical model of centrifugal compressor vaneless diffuser based on CFD calculations

2020 ◽  
Vol 178 ◽  
pp. 01014
Author(s):  
Olga Solovyeva ◽  
Aleksandr Drozdov
Keyword(s):  
Mathematical Model ◽  
Centrifugal Compressor ◽  
Similarity Criteria ◽  
Relative Width ◽  
Inlet Flow ◽  
Flow Angle ◽  
Gas Dynamic ◽  
Modelling Method ◽  
Vaneless Diffusers ◽  
The Mathematical Model

The approximate engineering techniques based on mathematical modelling are used in centrifugal compressor design. One of such methods is the well-proven Universal Modelling Method, developed in the scientific and research laboratory “Gas dynamics of turbo machines”, SPbPU. In the modern version of the compressor model, vaneless diffusers mathematical model was applied based on a generalization of the CFD calculations. The mathematical model can be used for vaneless diffusers with a relative width in the range of 1.4 – 10.0%, with a radial length up to 2.0, in the range of inlet flow angles 10 to 90 degrees, the inlet velocity coefficient in the range of 0.39 – 0.82, Reynolds number varying from 87 500 to 1 030 000. The model was also used for calculating low-flow-rate model stages with narrow diffusers with diffusers’ relative width in the range of 0.5 – 2.0%. The mathematical model showed lesser accuracy. To widen the model applicability, new series of CFD-calculations were executed. A series of vaneless diffusers was designed with relative width in the range of 0.6 – 1.2%, The gas-dynamic characteristics of loss coefficients and outlet flow angle versus inlet flow angle of diffuser were calculated. Regression analysis was used to process the calculated data. System of algebraic equations linking geometric, gas-dynamic parameters and similarity criteria was developed. The obtained equations are included in a new mathematical model of the Universal Modelling Method.

Inlet Flow Angle Determination of Transonic Compressor Cascades

1992 ◽  
Vol 114 (3) ◽  
pp. 487-493 ◽  
Author(s):  
W. Steinert ◽  
R. Fuchs ◽  
H. Starken
Keyword(s):  
Test Results ◽  
Flow Conditions ◽  
Suction Surface ◽  
Inlet Flow ◽  
Flow Angle ◽  
Transonic Compressor ◽  
Measuring Techniques ◽  
Special Measuring

Tests of transonic compressor cascades require special measuring techniques to determine the inlet flow angle around sonic inlet flow conditions. One of the main requirements for these methods is the ability to adjust the inlet flow angle during the test to a prescribed value. A method has been successfully applied that relies on theoretically determined suction surface velocities. The described method was applied in testing cascades at inlet Mack numbers between M1 = 0.75−1.18. The test results confirmed the practicability of this method.

Effects of Inlet Flow Field Conditions on the Performance of Centrifugal Compressor Diffusers: Part 1—Discrete-Passage Diffuser

1998 ◽  
Vol 122 (1) ◽  
pp. 1-10 ◽  
Author(s):  
V. G. Filipenco ◽  
S. Deniz ◽  
J. M. Johnston ◽  
E. M. Greitzer ◽  
N. A. Cumpsty
Keyword(s):  
Centrifugal Compressor ◽  
Total Pressure ◽  
Dynamic Pressure ◽  
Pressure Recovery ◽  
Flow Conditions ◽  
Recovery Coefficient ◽  
Inlet Flow ◽  
Flow Angle ◽  
Definition Of ◽  
Pressure Recovery Coefficient

This is Part 1 of a two-part paper considering the performance of radial diffusers for use in a high-performance centrifugal compressor. Part 1 reports on discrete-passage diffusers (shown in Fig. 1) while Part 2 describes a test of a straight-channel diffuser designed for equivalent duty. Two builds of discrete-passage diffuser were tested, with 30 and 38 separate passages. Both the 30 and 38 passage diffusers investigated showed comparable range of unstalled operation and similar level of overall diffuser pressure recovery. The paper concentrates on the influence of inlet flow conditions on the pressure recovery and operating range of radial diffusers for centrifugal compressor stages. The flow conditions examined include diffuser inlet Mach number, flow angle, blockage, and axial flow nonuniformity. The investigation was carried out in a specially built test facility, designed to provide a controlled inlet flow field to the test diffusers. The facility can provide a wide range of diffuser inlet velocity profile distortion and skew with Mach numbers up to unity and flow angles of 63 to 75 deg from the radial direction. The consequences of different averaging methods for the inlet total pressure distributions, which are needed in the definition of diffuser pressure recovery coefficient for nonuniform diffuser inlet conditions, were also assessed. The overall diffuser pressure recovery coefficient, based on suitably averaged inlet total pressure, was found to correlate well with the momentum-averaged flow angle into the diffuser. Furthermore, the pressure recovery coefficient was found to be essentially independent of the axial distortion at diffuser inlet, and the Mach number, over the wide flow range (from maximum flow to the beginning of flow instabilities) investigated. It is thus shown that the generally accepted sensitivity of diffuser pressure recovery performance to inlet flow distortion and boundary layer blockage can be largely attributed to inappropriate quantification of the average dynamic pressure at diffuser inlet. Use of an inlet dynamic pressure based on availability or mass-averaging in combination with definition of inlet flow angle based on mass average of the radial and tangential velocity at diffuser inlet removes this sensitivity. [S0889-504X(00)00101-X]

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