Straight Duct Supersonic Diffuser Flow in a Ludwieg Tube with Upstream Diaphragm.

1976 ◽  
Author(s):  
Nesim Abuaf
Keyword(s):  
Ludwieg Tube ◽  
Diffuser Flow ◽  
Supersonic Diffuser ◽  
Straight Duct

scholarly journals Casing Treatments on a Supersonic Diffuser for High Pressure Ratio Centrifugal Compressors

1982 ◽  
Author(s):  
Y. Ribaud ◽  
P. Avram
Keyword(s):  
High Pressure ◽  
Mass Flow ◽  
Pressure Ratio ◽  
Centrifugal Compressors ◽  
Flow Variation ◽  
High Pressure Ratio ◽  
Supersonic Inlet ◽  
Diffuser Flow ◽  
Supersonic Diffuser ◽  
Casing Treatments

Centrifugal compressors with high pressure ratios from 7 to 10 often have a very slow mass flow margin. Suitable casing treatments, including large openings at the diffuser throat connected to annular plenums, greatly increase the reduced mass flow range of the diffuser during supersonic inlet operation. In the region of reduced mass flow variation, the reduction of the diffuser flow is associated with a drop of the effectiveness. The use of a backswept centrifugal rotor allows the experiment to overcome this penalty.

Supersonic Diffusers With Reverse Flow Injection

1983 ◽  
Vol 105 (1) ◽  
pp. 47-52
Author(s):  
D. W. Kuntz ◽  
J. C. Dutton ◽  
S. H. White ◽  
A. L. Addy
Keyword(s):  
Flow Injection ◽  
Reverse Flow ◽  
Control Volume ◽  
Experimental Studies ◽  
High Energy ◽  
Pressure Recovery ◽  
Critical Parameters ◽  
Diffuser Flow ◽  
Sudden Enlargement ◽  
Supersonic Diffuser

In applications such as airborne high energy chemical lasers, diffuser size and weight can be critical parameters. This paper summarizes the authors’ research concerning the effects of flow injection into a supersonic diffuser in a direction opposite to that of the main flow. Experimental studies were conducted concerning the effect of diffuser performance, particularly length and pressure recovery, of this reverse flow, and a quasi-one-dimensional control volume analysis was performed to predict some of the diffuser flow properties. Single-stream, dual-stream, and sudden enlargement configurations were considered. This work has shown that a reverse flow can reduce the length of a diffuser while causing only a small decrease in overall pressure recovery.

Boundary Layer Flashback Model for Hydrogen Flames in Confined Geometries Including the Effect of Adverse Pressure Gradient

2020 ◽  
Author(s):  
Ólafur H. Björnsson ◽  
Sikke A. Klein ◽  
Joeri Tober
Keyword(s):  
Boundary Layer ◽  
Pressure Gradient ◽  
Flow Separation ◽  
Gradient Flow ◽  
Lewis Number ◽  
Adverse Pressure Gradient ◽  
Future Research ◽  
Diffuser Flow ◽  
Combustion Properties ◽  
Quenching Distance

Abstract The combustion properties of hydrogen make premixed hydrogen-air flames very prone to boundary layer flashback. This paper describes the improvement and extension of a boundary layer flashback model from Hoferichter [1] for flames confined in burner ducts. The original model did not perform well at higher preheat temperatures and overpredicted the backpressure of the flame at flashback by 4–5x. By simplifying the Lewis number dependent flame speed computation and by applying a generalized version of Stratford’s flow separation criterion [2], the prediction accuracy is improved significantly. The effect of adverse pressure gradient flow on the flashback limits in 2° and 4° diffusers is also captured adequately by coupling the model to flow simulations and taking into account the increased flow separation tendency in diffuser flow. Future research will focus on further experimental validation and direct numerical simulations to gain better insight into the role of the quenching distance and turbulence statistics.

Structural analysis of transonic inlet diffuser flow

2020 ◽  
Vol 2020 (0) ◽  
pp. S05420
Author(s):  
Taiju NAKA ◽  
Shinichiro NAKAO ◽  
Yoshiaki MIYAZATO
Keyword(s):  
Structural Analysis ◽  
Diffuser Flow

Effects of distributed pressure gradients on the pressure–strain correlations in a supersonic nozzle and diffuser

2014 ◽  
Vol 742 ◽  
pp. 466-494 ◽  
Author(s):  
Somnath Ghosh ◽  
Rainer Friedrich
Keyword(s):  
Supersonic Nozzle ◽  
Turbulent Pipe Flow ◽  
Pressure Gradients ◽  
Reynolds Stresses ◽  
Streamline Curvature ◽  
Flow Parameters ◽  
Diffuser Flow ◽  
Remarkable Agreement ◽  
Distributed Pressure

AbstractDirect numerical simulation (DNS), based on high-order numerical schemes, is used to study the effects of distributed pressure gradients on the redistribution of fluctuating kinetic energy in supersonic nozzle and diffuser flow with incoming fully developed turbulent pipe flow. Axisymmetric geometries and flow parameters have been selected such that shock waves are avoided and streamline curvature remains unimportant. Although mean extra rates of strain are quite small, strong changes in Reynolds stresses and their production/redistribution mechanisms are observed, in agreement with findings of Bradshaw (J. Fluid Mech., vol. 63, 1974, pp. 449–464). The central role of pressure–strain correlations in changing the Reynolds stress anisotropy is highlighted. A Green’s function-based analysis of pressure–strain correlations is presented, showing remarkable agreement with DNS data.

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