scholarly journals Effect of the Pitot Tube on Measurements in Supersonic Axisymmetric Underexpanded Microjets

Micromachines ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 235 ◽  
Author(s):  
Sergey Mironov ◽  
Vladimir Aniskin ◽  
Tatiana Korotaeva ◽  
Ivan Tsyryulnikov
Keyword(s):  
Wave Structure ◽  
Pitot Tube ◽  
Pressure Measurements ◽  
Turbulent Transition ◽  
Gas Dynamic ◽  
Pitot Pressure ◽  
Supersonic Core Length ◽  
Pitot Microtube ◽  
Unsteady Jet ◽  
Jet Axis

This paper describes the results of methodical investigations of the effect of the Pitot tube on measurements of gas-dynamic parameters of supersonic axisymmetric underexpanded real and model microjets. Particular attention is paid to distortions of Pitot pressure variations on the jet axis associated with the wave structure of the jet and to distortions of the supersonic core length. In experiments with model jets escaping from nozzles with diameters ranging from 0.52 to 1.06 mm into the low-pressure chamber, the measurements are performed by the Pitot tubes 0.05 to 2 mm in diameter. The results are analyzed together with the earlier obtained data for real microjets escaping from nozzles with diameters ranging from 10 to 340 µm where the parameters of real microjets were determined by the Pitot microtube 12 µm in diameter. Interaction of the Pitot tube with an unsteady jet in the laminar-turbulent transition region is investigated; the influence of this interaction on Pitot pressure measurements is determined, and a physical interpretation of this phenomenon is provided.

Effect of flat wall length on decay and shock structure of a supersonic square wall jet

2021 ◽  
pp. 095441002110580
Author(s):  
Venkata Satya Manikanta Tammabathula ◽  
Venkata Sai Krishna Ghanta ◽  
Tharaka Narendra Sridhar Bandla
Keyword(s):  
Supersonic Jet ◽  
Leading Edge ◽  
Shock Structure ◽  
Wall Jet ◽  
Pressure Measurements ◽  
Maximum Enhancement ◽  
Flat Wall ◽  
Decay Behaviour ◽  
Core Length ◽  
Supersonic Core Length

Experiments were conducted to find the effect of wall length on the decay behaviour and shock structure of a supersonic wall jet issuing from c-d nozzle of the square-shaped exit. A straight flat wall of width same as the side length of the square was attached to the lip of the nozzle such that the leading edge of the wall and the side of the square aligned properly which allowed the supersonic jet to graze past the flat wall. Experiments were conducted with five different wall lengths, that is, [Formula: see text] = 0.5, 1, 2, 4 and 8. Wall pressure measurements were made from leading edge to the trailing edge of the wall along its centreline. Schlieren flow visualization of the jet flow over the wall for the different wall lengths revealed the shock pattern and the effect of the wall length on the shock structure. The shock structure and jet deflection were significantly affected due to the presence of the wall. There was an upward jet deflection for [Formula: see text] up to [Formula: see text] whereas a downward jet deflection was observed for [Formula: see text]. Noticeable changes in the shock structure were observed for the wall lengths up to 2 D h. The wall length also significantly affected the jet decay characteristics and supersonic core length. Maximum enhancement in jet decay and maximum reduction in supersonic core length resulted when the wall length was [Formula: see text]. However, when the wall length was increased to [Formula: see text], there was a significant reduction in jet decay and a recovery of [Formula: see text]. Presence of wall always resulted a reduction in Lsc irrespective of wall length. The wall effect was to induce a more precipitous pressure drop closer to the nozzle exit, and a more gradual drop farther from it for [Formula: see text] > [Formula: see text].

Acceleration and Pressure Measurements during Wave-Structure Interactions

2001 ◽  
Author(s):  
Kuang-An Chang ◽  
Monroe Weber-Shirk ◽  
Edwin A. Cowen ◽  
Philip L.-F. Liu ◽  
Aaron R. Blake
Keyword(s):  
Wave Structure ◽  
Pressure Measurements

scholarly journals VISUALIZATION OF THE gas-dynamic STRUCTURE OF PLASMA FLOWS OF A PNK-50 plasma torchusing THE SHADOW METHOD

2018 ◽  
Vol 14 (4) ◽  
pp. 61-68 ◽  
Author(s):  
I P Gulyaev ◽  
V I Kuzmin ◽  
M P Golubev ◽  
P A Tyryshkin ◽  
A V Dolmatov
Keyword(s):  
Plasma Torch ◽  
Dynamic Structure ◽  
Reynolds Numbers ◽  
Air Plasma ◽  
Plasma Flows ◽  
Output Section ◽  
Modes Of Operation ◽  
Turbulent Transition ◽  
Gas Dynamic ◽  
Additional Mode

The paper presents the study of the gas-dynamic structure of air plasma flows produced by the PNK-50 spray torch using the shadow (schlieren) method. The operation of the plasma torch was studied in three different configurations, differing, among other things, by the diameter of the output section of the channel: 6, 8, 10 mm. The subsonic and supersonic modes of operation of the plasma torch were investigated in the range of plasma-forming air flow 1.4-10.5 g / s and arc current range 140-230 A.In all typical modes of operation of the plasma torch, the flow has a developed turbulent structure with a full angle of jet opening between 23 and 27 degrees. An additional mode of operation of the plasma torch with an output nozzle diameter of 14 mm allowed the realization of a laminar flow regime. It is established that the laminar-turbulent transition is observed in the range of Reynolds numbers 400 - 900. The pattern of supersonic flow impinging a flat barrier - a substrate for placedat a distance of 85 mm from the plasma torch, is visualized.

Velocity Measurements in Wet Steam Flows by Laser Anemometry and Pitot Tube

1975 ◽  
Vol 97 (1) ◽  
pp. 113-116 ◽  
Author(s):  
R. I. Crane ◽  
A. Melling
Keyword(s):  
Low Pressure ◽  
Laser Doppler Anemometer ◽  
Laser Doppler ◽  
Pitot Tube ◽  
Alternative Methods ◽  
Wet Steam ◽  
Velocity Measurements ◽  
Laser Anemometry ◽  
Pitot Pressure ◽  
Artificial Seeding

Velocities up to 200 m/s in condensing steam flows have been successfully measured using a laser Doppler anemometer, without artificial seeding. The performance of the system is described and results are compared with simultaneous pitot tube measurements. The discrepancy between the alternative methods used here for converting pitot pressure to velocity in subsonic wet flow becomes greater at higher speeds; extension of this work is discussed, with the objective of calibrating pitot tubes for use at high subsonic and low supersonic speeds encountered in low pressure turbines.

Pitot pressure measurements in a supersonic steam jet

2014 ◽  
Vol 58 ◽  
pp. 56-61 ◽  
Author(s):  
Ghassan Al-Doori ◽  
David R. Buttsworth
Keyword(s):  
Pressure Measurements ◽  
Pitot Pressure

A gun tunnel investigation of hypersonic free shear layers in a planar duct

1995 ◽  
Vol 299 ◽  
pp. 133-152 ◽  
Author(s):  
D. R. Buttsworth ◽  
R. G. Morgan ◽  
T. V. Jones
Keyword(s):  
Mach Number ◽  
High Speed ◽  
Mixing Layer ◽  
Spreading Rate ◽  
Shear Layers ◽  
Pressure Measurements ◽  
Rate Asymmetry ◽  
Pitot Pressure ◽  
Free Shear Layers ◽  
Mach 3

An experimental investigation of high Mach number free shear layers has been undertaken. The experiments were performed using a Mach 7 gun tunnel facility and a planar duct with injection from the base of a central strut producing a Mach 3 flow parallel to the gun tunnel stream. This configuration is relevant to the development of efficient scramjet propulsion, and the gun tunnel Mach number is significantly higher than the majority of previous supersonic turbulent mixing layer investigations reported in the open literature. Schlieren images and Pitot pressure measurements were obtained at four different convective Mach numbers ranging from 0 to 1.8. Only small differences between the four cases were detected, and the relatively large high-speed boundary layers at the trailing edge of the struct injector appear to strongly influence the shear layer development in each case. The Pitot pressure measurements indicated that, on average, the free shear layers all spread into the Mach 3 stream at an angle of approximately 1.4°, while virtually no spreading into the Mach 7 stream was detected until all of the low-speed stream was entrained. The free shear layers were simulated using a PNS code; however, the experimentally observed degree of spreading rate asymmetry could not be fully predicted with the k−ε turbulence model, even when a recently proposed compressibility correction was applied.

The expansion of a hypersonic turbulent boundary layer at a sharp corner

1975 ◽  
Vol 67 (4) ◽  
pp. 647-655 ◽  
Author(s):  
A. W. Bloy
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Wall Pressure ◽  
Pressure Measurements ◽  
Sharp Corner ◽  
Transfer Theory ◽  
Heat Transfer Theory ◽  
Surface Data ◽  
Pitot Pressure

A sharp wedge expansion flap was tested in the von Kámán Institute Long-shot tunnel at Mach 16 and data on the wall pressure and heat transfer were obtained. Pitot pressure measurements in the boundary layer just ahead of the expansion flap were also made. The surface data are compared with predictions from a characteristics solution for the boundary-layer expansion and from a simple heat-transfer theory.

Spatial-Wave Structure of Controlled Disturbances in 3D Supersonic Boundary Layer

2011 ◽  
Vol 6 (4) ◽  
pp. 5-15
Author(s):  
Gleb Kolosov ◽  
Aleksandra Panina ◽  
Aleksandr Kosinov ◽  
Yuri Yermolaev ◽  
Nikolay Semionov
Keyword(s):  
Boundary Layer ◽  
Oscillation Amplitude ◽  
Wave Structure ◽  
Supersonic Boundary Layer ◽  
Normal Direction ◽  
Swept Wing ◽  
Linear Region ◽  
Turbulent Transition ◽  
Linear And Nonlinear ◽  
First Time

Results of experimental investigation of controlled disturbance excitation in the boundary layer of thing swept wing at Mach number M = 2 are presented. Regions of the linear and nonlinear natural pulsation development are determined. For the first time spatial-wave structure of controlled disturbances generated by local pulsation source is studied in detail in the linear region of laminar-turbulent transition. It is found, that maximum of artificial oscillation amplitude is localized in normal direction regarding to the swept wing surface as for spatial distributions as well as for most powerful part of wave spectra

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