scholarly journals Control of CD Nozzle Flow using Microjets at Mach 2.1

2019 ◽  
Vol 8 (9S2) ◽  
pp. 631-635 ◽  
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
Pressure Distribution ◽  
Active Control ◽  
Control Mechanism ◽  
Area Ratio ◽  
Wall Pressure ◽  
Orifice Diameter ◽  
Nozzle Flow ◽  
Circle Diameter

This paper reports the outcome of the wind tunnel investigation performed to study the effectiveness of the control jets to regulate the base pressure in an abruptly expanded circular pipe. Tiny jets four in a number, of 1 mm orifice diameter located at ninety degrees in cross shape along a pitch circle diameter (PCD) of 1.3 as a control mechanism were employed. The Mach numbers and the area ratio of the study were 2.1, and 4.84. The length-to-diameter (L/D) ratio of the duct tested was varied from 10 to 1. Nature of the flow in the duct, as well as static wall pressure distribution in the suddenly enlarged duct, was recorded. The main aim of this study was to assess the influence of the active control in the form of tiny jets on the flow field as well as the nature of the flow, and also the development of the flow in the duct. The results obtained in this study show that the flow field, as well as the wall pressure distribution, is not adversely influenced by the tiny jets. The minimum duct length seems to be 2D for NPR's in the range five and above. However, for all the level of expansion of the present study, the minimum duct length needed for the flow to remain attached seems to be 3D

scholarly journals Experimental Research of Wall Pressure Distribution and Effect of Micro Jet at Mach 1.5

2019 ◽  
Vol 8 (2S3) ◽  
pp. 1000-1003 ◽  
Keyword(s):  
Adverse Effect ◽  
Flow Field ◽  
Pressure Distribution ◽  
Area Ratio ◽  
Wall Pressure ◽  
Rapid Expansion ◽  
Base Region ◽  
Active Controls ◽  
Circle Diameter

In this paper, a study on the effect of the control on the wall pressure as well as the quality of the flow when tiny jets were employed. The small jet aimed to regulate the base pressure at the base region of the suddenly expanded duct and wall pressure distribution is carried out experimentally. The convergent-divergent (CD) nozzle with a suddenly expanded duct was designed to observe the wall pressure distribution with and without control using small jets. In order to obtain the results with the effect of controlled four tiny jets of 1 mm diameter located at a ninety-degree interval along a pitch circle diameter (PCD) of 1.3 times the CD nozzle exit diameter in the base, region was employed as active controls. The Mach numbers of the rapidly expanded are 1.5. The jets were expanded quickly into an axis-symmetry duct with an area ratio of 4.84. The length-todiameter (L/D) ratio of the rapid expansion duct was diverse from 10 to 1. There is no adverse effect due to the presence of the tiny jets on the flow field as well as the quality of the flow in the duct

scholarly journals Effects of Micro jets on the Flow Field of the Duct with Sudden Expansion

2019 ◽  
Vol 8 (9S2) ◽  
pp. 636-640 ◽  
Keyword(s):  
Mach Number ◽  
Flow Field ◽  
Pressure Distribution ◽  
Pressure Ratio ◽  
Wall Pressure ◽  
Base Pressure ◽  
Sudden Expansion ◽  
Orifice Diameter ◽  
Nozzle Pressure ◽  
Circle Diameter

This paper presents the results of an experimental investigation to study the effectiveness of the control jets to control base pressure in rapidly expanded circular tubes. Four tiny jets of 1 mm orifice diameter located at ninety degrees interval in cross shape along a pitch circle diameter of 1.3. The Mach number, the L/D ratio, and the area ratio of the study were 2.8, from 1 to 10, and 4.84, respectively. The nature of the flow field, the development of the flow in the duct, as well as the static wall pressure distribution in the duct was measured and discussed. The results indicate that the tiny jets can be used as an active dynamic controller for the base pressure. The wall pressure distribution is not adversely influenced by the small jets. From the present investigation, it is evident that for a given Mach number and nozzle pressure ratio one can identify the minimum duct L/D needed for the flow remained attached with the wall of the duct. The trend for the duct length L = 5D seems to show different results, due to the influence of back pressure and the peak pressure values are also less than that those were for higher L/D ratios, especially in respect of L/D = 5. Further, the flow field has smoothened in the duct, and wall pressure values with and without micro jets are identical. This trend continues until L/D = 4, then later for lower L/Ds like L/D = 3, the flow seems to be attached at higher NPRs. But for lower NPRs the flow is not attached

scholarly journals Influence of Control Mechanism on the Flow field of Duct at Mach 1.2 for Area Ratio 2.56

2019 ◽  
Vol 8 (6S4) ◽  
pp. 1135-1138 ◽  
Keyword(s):  
Experimental Investigation ◽  
Mach Number ◽  
Flow Field ◽  
Recirculation Zone ◽  
Control Mechanism ◽  
Area Ratio ◽  
Central Axis ◽  
Orifice Diameter ◽  
Field Development

In this paper, the outcome of the experimental investigation and the flow field development in the duct at supersonic Mach number of 1.2 is presented. The experiments were conducted at various NPR which covers the condition of correct expansion and under expansion. A Convergent-divergent (C-D) nozzle which is connected with the suddenly expanded duct of the diameter of 16 mm of area ratio 2.56. The recirculation zone is controlled by using the microjets of 1 mm of orifice diameter which are placed at 90 degrees interval at 6.5 mm from the central axis of the main jet. The L/D of the duct was used in the investigation was from 1 to 10, and the NPR at which the experiments were conducted considered are in the range from 3, 5, 7, 9 and 11.

scholarly journals Experimental Research on Wall Pressure Distribution in C-D Nozzle at Mach number 1.1 for Area Ratio 3.24

2019 ◽  
Vol 8 (2S3) ◽  
pp. 971-975 ◽  
Keyword(s):  
Experimental Investigation ◽  
Mach Number ◽  
Flow Field ◽  
Pressure Distribution ◽  
Pressure Ratio ◽  
Area Ratio ◽  
Wall Pressure ◽  
Circulation Zone ◽  
Nozzle Pressure Ratio ◽  
Nozzle Pressure

In this experimental investigation the work reported is about the influence of control on the flow field in the suddenly expanded duct at low supersonic Mach number. A Convergent-divergent (CD) nozzle was designed and fabricated out of brass material assembled with the suddenly expanded duct which was also made of brass material. At the re-circulation zone, the flow field was controlled by using the micro jets of 1 mm diameter as an orifice and the control was arranged at an interval of 90 degrees at 6.5 mm from the central axis of the main jet. The measured wall pressure distribution was presented for Mach number 1.1 for the duct diameter of 18 mm leading to the area ratio 3.24. The L/D ratio of the duct was varied from 1 to 10, and the nozzle pressure ratio (NPR) considered for the experiments was from 3, 5, 7, 9 and 11. The present results have demonstrated that the micro jets do not influence the flow field in the duct adversely and the flow field remained identical in the presence of control or absence of control

scholarly journals Role of Active Control in Increasing Base Pressure at Sonic Mach Number

2019 ◽  
Vol 8 (2S3) ◽  
pp. 966-970
Keyword(s):  
Mach Number ◽  
Active Control ◽  
Experimental Analysis ◽  
Control Mechanism ◽  
Area Ratio ◽  
Base Pressure ◽  
Percentage Increase ◽  
Maximum Increase ◽  
Nozzle Pressure

Use of micro jets as an active control mechanism to control the base pressure in suddenly expanded flow from the C-D nozzle exhausted to the duct is investigated in this article. Experimental analysis is carried out at sonic Mach number and different nozzle pressure ratios. The enlarged diameter used in this investigation is 16 mm, 22.5 mm, and 27.5 mm. The length and diameter of the duct where the flow expands are also varied during the analysis. The role played by four micro jets of 1 mm diameter as an orifice to regulate the base pressure. The results as the percentage increase in base pressure are plotted for different level expansion and area ratio. For higher NPR = 7, the control significantly increases the base pressure without disturbing the wall pressure distribution. L/D = 3 and 4 seems to be optimum in resulting in a maximum increase in base pressure. For lower area ratio the minimum duct length required is L/D = 3, whereas for the highest area-ratio this limit is L/D = 4

scholarly journals Effect of Area Ratio on Base Pressure in a Suddenly Expanded Duct for Under Expanded Flow ft Mach 1.87

2013 ◽  
pp. 198-202
Author(s):  
M. Ahmed Ali Baig ◽  
Sher Afghan Khan ◽  
Mohammad Yunus Khan
Keyword(s):  
Experimental Investigation ◽  
Mach Number ◽  
Active Control ◽  
Pressure Field ◽  
Area Ratio ◽  
Wall Pressure ◽  
Base Pressure ◽  
Air Injection ◽  
Minimum Length ◽  
Percent Increase

The results of an experimental investigation carried out to control the base pressure in a suddenly expanded axi-symmetric passage is presented in this paper. An active control in the form of micro jets is employed to control the base pressure. Air injection at four locations at the base, symmetric to the nozzle axis is used as the active control. The jet Mach number studied and the area ratios are 1.87, and 2.56, 3.24, 4.84, and 6.25. The L/D ratio is varied from 10 to 1. The experiments are conducted at a fixed level of under expansion (i.e. Pe/Pa = 1.5). In addition to base pressure, wall pressure field along the duct was also measured. As high as 80 percent increase in base pressure was achieved for certain combination of parameters of the present study. The minimum Length-todiameter ratio of the duct required is L/D = 2 for area ratios 6.25 and 4.84. Whereas, this requirement is L/D = 1 for area ratios 2.56 and 3.24.

scholarly journals Inspection of Supersonic Flows in a CD Nozzle using Experimental Method

2019 ◽  
Vol 8 (2S3) ◽  
pp. 996-999 ◽  
Keyword(s):  
Mach Number ◽  
High Speed ◽  
Area Ratio ◽  
Wall Pressure ◽  
Nozzle Flow ◽  
Sonic Velocity ◽  
Pressure Data ◽  
Exit Mach Number ◽  
High Speed Flows ◽  
Jet Axis

In high speed flows nozzles are used to change pressure energy to kinetic energy which in turn is used to produce thrust. In a converging-diverging nozzle, flow is augmented from subsonic to sonic velocity at the throat and further expanded to supersonic velocities at the exit. In this paper, an experimental study is performed to evaluate the supersonic flow in a CD nozzle with a suddenly expanded duct. At the base of the nozzle, the base pressure is controlled by employing tiny jets of 1 mm diameter with a circular crosssection having exit Mach number of as unity are arranged at ninety degrees at a PCD of 13 mm and 6.5 mm from the central jet axis. Obtained wall pressure distribution is shown for Mach number 2.8, and Axi-symmetric round brass duct was used to join micro-jets, an area ratio of that duct is 3.24. Tests were conducted for L/D from 10 to 1, and the level of expansion for tests considered for wall pressure data acquisition was from 3, 5, 7, 9 and 11. The results indicate that the flow field was not aggravated due to the deployment of the control.

scholarly journals Active Control of Wall Pressure Flow Field at Low Supersonic Mach Numbers

2016 ◽  
Vol 16 (053) ◽  
pp. 90-98 ◽  
Author(s):  
Mohammed Asad Ullah ◽  
Musavir Bashir ◽  
Ayub Janvekar ◽  
S. A. Khan
Keyword(s):  
Flow Field ◽  
Active Control ◽  
Wall Pressure ◽  
Pressure Flow ◽  
Mach Numbers

Blade Curve Influences on Performance of Savonius Rotors: Experimental and Numerical

2010 ◽  
Author(s):  
Ali Kianifar ◽  
Morteza Anbarsooz ◽  
Mohammad Javadi
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Wind Tunnel ◽  
Flow Field ◽  
Pressure Distribution ◽  
Power Coefficient ◽  
Blade Surface ◽  
Wind Tunnel Tests ◽  
Savonius Rotor ◽  
Circular Curves

In this study, the effect of blade curve on the power coefficient of a Savonius rotor is investigated by means of numerical simulation and wind tunnel tests. The tests were conducted on six rotors with identical dimensions but different blade curves, and the influences of blade curve and Reynolds number were studied. Followed by a simulation of the flow field around rotors with identical semi-circular curves and different overlaps, torque was calculated using pressure distribution on the blade surface, and the effect of Reynolds number and blade curve were studied on torque as well. Results indicate that changing the blade curve affects the power coefficient and torque by causing different drag coefficients. Also the rotor that yields the highest power coefficient and torque in one revolution compared with other rotors is highlighted.

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