scholarly journals Effect of Mach number on Wall Pressure Flow Field for Area Ratio 2.56

2014 ◽  
Vol 11 (2) ◽  
pp. 56-64
Author(s):  
Syed Ashfaq ◽  
◽  
S. A Khan

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


2019 ◽  
Vol 8 (2S3) ◽  
pp. 1000-1003 ◽  

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


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.


Author(s):  
M. Ahmed Ali Baig ◽  
Sher Afghan Khan ◽  
Mohammad Yunus Khan

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.


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.


2016 ◽  
Vol 16 (053) ◽  
pp. 90-98 ◽  
Author(s):  
Mohammed Asad Ullah ◽  
Musavir Bashir ◽  
Ayub Janvekar ◽  
S. A. Khan

2022 ◽  
Author(s):  
Sher Afghan Khan ◽  
Zakir Ilahi Chaudhary ◽  
Maughal Ahmed Ali Baig ◽  
Ridwan ◽  
K. M. Chethan ◽  
...  

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


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


2016 ◽  
Vol 16 (053) ◽  
pp. 99-107 ◽  
Author(s):  
Musavir Bahir ◽  
Qummare Azam ◽  
S. A. Khan ◽  
M. Ahmed Ali Baig

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