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Mohammad Farahani

Bio: Mohammad Farahani is an academic researcher from Sharif University of Technology. The author has contributed to research in topics: Supersonic speed & Mach number. The author has an hindex of 10, co-authored 31 publications receiving 274 citations. Previous affiliations of Mohammad Farahani include Shahid Beheshti University of Medical Sciences and Health Services.

Papers
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Journal ArticleDOI
TL;DR: In this article, the performance and the buzz onset of a supersonic mixed-compression axisymmetric intake were experimentally investigated and the results showed that applying the bleed at a position near the intake entrance and reducing the bleed entrance slant angle and width all improved the intake performance considerably.
Abstract: The performance and the buzz onset of a supersonic mixed-compression axisymmetric intake are experimentally investigated. Effects of the slot bleed position, angle, and width on the intake performance and on the buzz initiation at three different Mach numbers of 1.8, 2.0, and 2.2 and at a zero degree angle of attack are studied. The intake performance is assessed using the total pressure recovery, mass flow ratio, flow distortion, and bleed mass flow ratio. The results show that applying the bleed at a position near the intake entrance and reducing the bleed entrance slant angle and width all improve the intake performance considerably. Moreover, these parameters postpone the buzz onset. In addition, it is found that the vertical position of the intersection point of the barrier and normal shocks plays an important role in the intake pressure recovery.

41 citations

Journal ArticleDOI
TL;DR: In this paper, the effects of various boundary-layer bleed locations on the stability of an axisymmetric supersonic inlet has been investigated experimentally, and the results show that, based on the individual design of an inlet, a location can be found that spilled normal shock stands at this location and consequently separation starts at the buzz onset.
Abstract: Effects of various boundary-layer bleed locations on the stability of an axisymmetric supersonic inlet has been investigated experimentally. The bleeds were located on the inlet compression cone and were designed to improve the stability margin of the inlet. The main objective of the study was to identify the boundary-layer bleed location and its effects on the improvement of the stability margin of the inlet. In addition, a buzz precursor detection methodology based on the rms level has been introduced. Experiments have been carried out on a mixed-compression inlet with a design Mach number of 2.0 and three different bleed locations at three freestream Mach numbers of 1.8, 2.0, and 2.2. All tests were conducted at an angle of attack of 0 deg. The results show that, based on the individual design of an inlet, a location can be found that the spilled normal shock stands at this location and consequently separation starts at the buzz onset. If the bleed slot is located in this place, the subcritical perform...

39 citations

Journal ArticleDOI
TL;DR: In this paper, the influence of angle of attack and mass flow rate on the inlet buzz phenomenon at a freestreamMach number of 2 and at various angles of attack 0-10 deg.
Abstract: Anaxisymmetric supersonic inlet was tested to study the influence of angle of attack andmass flow rate on the inlet buzz phenomenon at a freestreamMach number of 2 and at various angles of attack 0–10 deg. For each angle of attack, two main frequencies for the buzz were seen in the data. For the moderate mass flow rates, small-amplitude and high-frequency oscillation occurred. In this operation stage, both highand low-frequency oscillations exist, but the higher one is dominant and is very close to the frequency of the second acoustic resonance mode. At lower mass flow, however, low-frequency and large-amplitude oscillation occurred that had a single frequency with a constant period. Increasing the angle of attack decreased the inlet performance and limited the stability margin. At intermediate values of themass flow, the buzz frequencywas seen to be independent of the angle of attack, but, for the lower mass flow rates and at high angles of attack, the frequency of the buzz at front portions of the inlet varied. However, the diffuser end still has a constant frequency. In addition, the total-pressure signal had behavior similar to that of the static data with approximately the same frequency.

25 citations

Journal ArticleDOI
TL;DR: In this article, an experimental study was carried out on an axisymmetric supersonic inlet with external compression, where shadowgraph flow visualization, together with a high speed camera, was used to capture the external shock structure in front of the inlet.

22 citations

Journal ArticleDOI
01 Mar 2013
TL;DR: In this article, a computational fluid dynamics code was developed to compute the flow inside and around a supersonic external compression axisymmetric intake, solving the Reynolds-averaged Navier-Stokes equation.
Abstract: A computational fluid dynamics code was developed to compute the flow inside and around a supersonic external compression axisymmetric intake. The code solves the Reynolds-averaged Navier–Stokes eq...

20 citations


Cited by
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Book ChapterDOI
01 Jan 1997
TL;DR: The boundary layer equations for plane, incompressible, and steady flow are described in this paper, where the boundary layer equation for plane incompressibility is defined in terms of boundary layers.
Abstract: The boundary layer equations for plane, incompressible, and steady flow are $$\matrix{ {u{{\partial u} \over {\partial x}} + v{{\partial u} \over {\partial y}} = - {1 \over \varrho }{{\partial p} \over {\partial x}} + v{{{\partial ^2}u} \over {\partial {y^2}}},} \cr {0 = {{\partial p} \over {\partial y}},} \cr {{{\partial u} \over {\partial x}} + {{\partial v} \over {\partial y}} = 0.} \cr }$$

2,598 citations

01 Jan 2005
TL;DR: In this paper, an approximate analytical expression of the critical pull-in gap with Casimir force is presented by the perturbation theory, from which one can notice the nonlinear effect of Casimir forces on the pullin parameters.
Abstract: Casimir effect on the critical pull-in gap and pull-in voltage of nanoelectromechanical switches is studied. An approximate analytical expression of the critical pull-in gap with Casimir force is presented by the perturbation theory. The corresponding pull-in parameters are computed numerically, from which one can notice the nonlinear effect of Casimir force on the pull-in parameters. The detachment length has been presented, which increases with increasing thickness of the beam.

192 citations

01 Jan 2016
TL;DR: The analysis and design principles of mems devices is universally compatible with any devices to read, and is available in the digital library an online access to it is set as public so you can get it instantly.
Abstract: Thank you very much for downloading analysis and design principles of mems devices. Maybe you have knowledge that, people have search hundreds times for their favorite novels like this analysis and design principles of mems devices, but end up in malicious downloads. Rather than reading a good book with a cup of coffee in the afternoon, instead they cope with some infectious bugs inside their laptop. analysis and design principles of mems devices is available in our digital library an online access to it is set as public so you can get it instantly. Our digital library hosts in multiple locations, allowing you to get the most less latency time to download any of our books like this one. Kindly say, the analysis and design principles of mems devices is universally compatible with any devices to read.

125 citations

E E Wilson1
01 Jan 1925
TL;DR: This paper sketches in the high lights of aircraft engine design showing the development to date, the possibilities of the future, and the underlying fundamental principles of the engine design.
Abstract: From Introduction: "The subject of this paper is so broad in scope that a large volume might be devoted to it. In a short paper of this kind it is possible simply to sketch in the high lights of aircraft engine design showing the development to date, the possibilities of the future, and the underlying fundamental principles. Summarizing this development and referring to the graph (Fig.1), we that there is now a water-cooled engine in every power from 150 to 800 HP. and an air-cooled engine in the 200 to 400 HP. classes."

118 citations

Journal ArticleDOI
TL;DR: In this article, the performance and the buzz onset of a supersonic mixed-compression axisymmetric intake were experimentally investigated and the results showed that applying the bleed at a position near the intake entrance and reducing the bleed entrance slant angle and width all improved the intake performance considerably.
Abstract: The performance and the buzz onset of a supersonic mixed-compression axisymmetric intake are experimentally investigated. Effects of the slot bleed position, angle, and width on the intake performance and on the buzz initiation at three different Mach numbers of 1.8, 2.0, and 2.2 and at a zero degree angle of attack are studied. The intake performance is assessed using the total pressure recovery, mass flow ratio, flow distortion, and bleed mass flow ratio. The results show that applying the bleed at a position near the intake entrance and reducing the bleed entrance slant angle and width all improve the intake performance considerably. Moreover, these parameters postpone the buzz onset. In addition, it is found that the vertical position of the intersection point of the barrier and normal shocks plays an important role in the intake pressure recovery.

41 citations