Mathematical and Physical Analysis of the Effect of Conical and Detached Shock Waves at the Tip of a Static Probe in an Experimental Chamber

2021 ◽  
Vol 105 (1) ◽  
pp. 627-635
Author(s):  
Pavla Šabacká ◽  
Jiří Maxa ◽  
Anna Maxová
Keyword(s):  
Supersonic Flow ◽  
Static Pressure ◽  
Experimental Chamber ◽  
Physical Analysis ◽  
Pressure Measurements ◽  
Scientific Instruments ◽  
Electronic Technology ◽  
Vacuum Chambers ◽  
University Of Technology ◽  
Flow Through

As part of the research in the field of pumping vacuum chambers in the Environmental Electron Microscope, research on supersonic flow through apertures is being carried out at the Department of Electrical and Electronic Technology of the Brno University of Technology in cooperation with the Institute of Scientific Instruments of the CAS. This paper deals with the influence of the shape of the static probe cone design for static pressure measurements in the supersonic flow regime in the Experimental Chamber. The cone of the probe has an effect on the shape of the shock wave, which significantly influences the detected static pressure value.

Mathematical and Physical Analysis of Pressure Gradient in the Experimental Chamber for Subsequent Comparison with Optical Methods

2021 ◽  
Vol 105 (1) ◽  
pp. 601-608
Author(s):  
Robert Bayer ◽  
Anna Maxová
Keyword(s):  
Optical Methods ◽  
Experimental Chamber ◽  
Physical Analysis ◽  
Pressure Gradients ◽  
Scientific Instruments ◽  
Electronic Technology ◽  
Vacuum Chambers ◽  
University Of Technology ◽  
Flow Through ◽  
Subsequent Comparison

As a part of the research in the field of pumping vacuum chambers in the Environmental Electron Microscope, a research on supersonic flow through the Appertures is being carried out at the Department of Electrical and Electronic Technology of the Brno University of Technology in cooperation with the Institute of Scientific Instruments of the Czech Academy of Science. This paper deals with the possibility of investigating shock waves using the Shlieren optical method, which allows to observe pressure gradients as the first derivation of pressure.

Analysis of the Effect of Reflected Shock Waves in the Experimental Chamber

2021 ◽  
Vol 105 (1) ◽  
pp. 589-599
Author(s):  
Jiří Maxa ◽  
Pavla Šabacká ◽  
Robert Bayer
Keyword(s):  
Electron Microscope ◽  
Supersonic Flow ◽  
Shock Waves ◽  
Vacuum Chamber ◽  
Experimental Chamber ◽  
Scientific Instruments ◽  
Electronic Technology ◽  
Reflected Shock ◽  
University Of Technology ◽  
Flow Through

As part of the research in the field of vacuum chamber pumping in the Environmental Electron Microscope, research on supersonic flow through apertures is being carried out at the Department of Electrical and Electronic Technology of Brno University of Technology in cooperation with the Institute of Scientific Instruments of the CAS. This paper deals with the influence of reflected shock waves on the resulting flow in the pumped part of the Experimental Chamber.

Mathematical-Physical Analysis of Drag Force of a .223 REM Caliber Projectile

2021 ◽  
Vol 105 (1) ◽  
pp. 637-645
Author(s):  
Pavla Šabacká ◽  
Jiří Maxa ◽  
Filip Maxa
Keyword(s):  
Shock Wave ◽  
Electron Microscope ◽  
Supersonic Flow ◽  
Drag Force ◽  
Physical Analysis ◽  
Vacuum Chambers ◽  
Aerodynamic Shape

This article deals with the mathematical and physical analysis of the drag force affecting a .223 REM projectile as a basis for further modification of the aerodynamic shape of the projectile by changing the perpendicular shock wave at the projectile tip into a conical one. For the analyses, the Department’s experience from the analysis of the supersonic flow generated during the pumping of the vacuum chambers of the electron microscope was used.

Wall Pressure Measurements in a Convergent–Divergent Nozzle with Varying Inlet Asymmetry

2016 ◽  
Vol 33 (2) ◽  
Author(s):  
C. Senthilkumar ◽  
S. Elangovan ◽  
E. Rathakrishnan
Keyword(s):  
Mach Number ◽  
Supersonic Flow ◽  
Flow Separation ◽  
Static Pressure ◽  
Flow Characteristics ◽  
Pressure Measurements ◽  
Separation Region ◽  
Number Ratio ◽  
Inlet Angle ◽  
Nozzle Inlet

AbstractIn this paper, flow separation of a convergent–divergent (C-D) nozzle is placed downstream of a supersonic flow delivered from Mach 2.0 nozzle is investigated. Static pressure measurements are conducted using pressure taps. The flow characteristics of straight and slanted entry C-D nozzle are investigated for various NPR of Mach 2.0 nozzle. The effect of asymmetry at inlet by providing 15°, 30°, 45° and 57° cut is analyzed. Particular attention is given to the location of the shock within the divergent section of the test nozzle. This location is examined as a function both NPR of Mach 2.0 nozzle and test nozzle inlet angle. Some of the measurements are favorably compared to previously developed theory. A Mach number ratio of 0.81 across the flow separation region was obtained.

scholarly journals Application of Prandtl’s Theory in the Design of an Experimental Chamber for Static Pressure Measurements

Sensors ◽  
2021 ◽  
Vol 21 (20) ◽  
pp. 6849
Author(s):  
Pavla Šabacká ◽  
Vilém Neděla ◽  
Jiří Maxa ◽  
Robert Bayer
Keyword(s):  
Supersonic Flow ◽  
Laval Nozzle ◽  
Pressure Sensors ◽  
Small Diameter ◽  
Correct Choice ◽  
Primary Electron ◽  
Experimental Chamber ◽  
State Variables ◽  
Vacuum Chambers ◽  
Low Pressures

Pumping in vacuum chambers is part of the field of environmental electron microscopy. These chambers are separated from each other by a small-diameter aperture that creates a critical flow in the supersonic flow regime. The distribution of pressure and shock waves in the path of the primary electron beam passing through the differentially pumped chamber has a large influence on the quality of the resulting microscope image. As part of this research, an experimental chamber was constructed to map supersonic flow at low pressures. The shape of this chamber was designed using mathematical–physical analyses, which served not only as a basis for the design of its geometry, but especially for the correct choice of absolute and differential pressure sensors with respect to the cryogenic temperature generated in the supersonic flow. The mathematical and physical analyses presented here map the nature of the supersonic flow with large gradients of state variables at low pressures at the continuum mechanics boundary near the region of free molecule motion in which the Environmental Electron Microscope and its differentially pumped chamber operate, which has a significant impact on the resulting sharpness of the final image obtained by the microscope. The results of this work map the flow in and behind the Laval nozzle in the experimental chamber and are the initial basis that enabled the optimization of the design of the chamber based on Prandtl’s theory for the possibility of fitting it with pressure probes in such a way that they can map the flow in and behind the Laval nozzle.

A study of Turbulent Flow in Pipe Contractions

1996 ◽  
Vol 210 (3) ◽  
pp. 171-180 ◽  
Author(s):  
P R Bullen ◽  
D J Cheeseman ◽  
L A Hussain
Keyword(s):  
Static Pressure ◽  
Laser Doppler Anemometer ◽  
Area Ratio ◽  
Pressure Measurements ◽  
Number Range ◽  
Two Component ◽  
Flow Features ◽  
Flow Through ◽  
Loss Coefficients ◽  
Turbulent Water

An experimental study of turbulent water flow through abrupt contractions was carried out in order to determine the detailed flow field. Wall static pressure measurements enabled the calculation of pressure loss coefficients for a range of contraction area ratios from 0.13 to 0.67 over a Reynolds number range of 40000–200000. The effect of variations in contraction sharpness was also established. Measurements of mean velocities and turbulence intensities were made using a two-component laser Doppler anemometer for one area ratio of 0.332 to establish the detailed flow features.

scholarly journals Response surface analysis of nozzle parameters at supersonic flow through microjets

2021 ◽  
pp. 1-16
Author(s):  
Turki Al-Khalifah ◽  
Abdul Aabid ◽  
Sher Afghan Khan ◽  
Muhammad Hanafi Bin Azami ◽  
Muneer Baig
Keyword(s):  
Supersonic Flow ◽  
Response Surface ◽  
Surface Analysis ◽  
Response Surface Analysis ◽  
Flow Through

Distortion reconstruction in S-ducts from wall static pressure measurements

2018 ◽  
Vol 28 (5) ◽  
pp. 1134-1155 ◽  
Author(s):  
Pierre Grenson ◽  
Eric Garnier
Keyword(s):  
Static Pressure ◽  
Active Flow Control ◽  
Hybrid Approach ◽  
Reconstruction Algorithm ◽  
Stochastic Estimation ◽  
Pressure Measurements ◽  
Reconstruction Algorithms ◽  
Detached Eddy Simulation ◽  
Flow Distortion ◽  
Content Type

Purpose This paper aims to report the attempts for predicting “on-the-fly” flow distortion in the engine entrance plane of a highly curved S-duct from wall static pressure measurements. Such a technology would be indispensable to trigger active flow control devices to mitigate the intense flow separations which occur in specific flight conditions. Design/methodology/approach Evaluation of different reconstruction algorithms is performed on the basis of data extracted from a Zonal Detached Eddy Simulation (ZDES) of a well-documented S-Duct (Garnier et al., AIAA J., 2015). Contrary to RANS methods, such a hybrid approach makes unsteady distortions available, which are necessary information for reconstruction algorithm assessment. Findings The best reconstruction accuracy is obtained with the artificial neural network (ANN) but the improvement compared to the classical linear stochastic estimation (LSE) is minor. The different inlet distortion coefficients are not reconstructed with the same accuracy. KA2 coefficient is finally identified as the more suited for activation of the control device. Originality/value LSE and its second-order variant (quadratic stochastic estimation [QSE]) are applied for reconstructing instantaneous stagnation pressure in the flow field. The potential improvement of an algorithm based on an ANN is also evaluated. The statistical link between the wall sensors and 40-Kulite rake sensors are carefully discussed and the accuracy of the reconstruction of the most used distortion coefficients (DC60, RDI, CDI and KA2) is quantified for each estimation technique.

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