Lip Separate Flow Blowing and Analysis of Coherence of Inlet

1986 ◽  
Vol 108 (3) ◽  
pp. 562-565
Author(s):  
Z. W. He ◽  
S. Y. Zhang
Keyword(s):  
Boundary Layer ◽  
Total Pressure ◽  
Pressure Fluctuations ◽  
Separate Flow ◽  
Interaction Region ◽  
Separation Region ◽  
Layer Interaction ◽  
Shock Boundary Layer Interaction ◽  
Boundary Layer Interaction

It is found experimentally that blowing at the lip separation of an inlet obviously reduces the turbulence at the inlet exit, and apparently reduces the intensity of pressure fluctuations caused by the shock-boundary layer interaction downstream of the throat. The coherence between pressure in the interaction region and total pressure at the exit is also reduced. The coherence between the pressure in the lip separation region and total pressure at the exit is 0.32. If, in addition, there is a stronger shock downstream of the throat, the abovementioned coherence is reduced to 0.06.

scholarly journals Lip Separate Flow Blowing and Analysis of Coherence of Inlet

1985 ◽  
Author(s):  
He Zhongwei ◽  
Zhang Shiying
Keyword(s):  
Boundary Layer ◽  
Total Pressure ◽  
Pressure Fluctuations ◽  
Separate Flow ◽  
Interaction Region ◽  
Separation Region ◽  
Layer Interaction ◽  
Shock Boundary Layer Interaction ◽  
Boundary Layer Interaction

It is found in the experiments that blowing at the lip separation of the inlet obviously reduces the turbulences at the inlet exit, and apparently reduces the intensity of pressure fluctuations caused by the shock-boundary layer interaction down-stream of throat. The coherence between pressure in the interaction region and total pressure at the exit is also reduced. The coherence between the pressure in the lip separation region and total pressure at the exit is 0.32. If, in addition, there is a stronger shock down-stream of the throat the above mentioned coherence is reduced to 0.06.

Role of Shock and Boundary Layer Separation on Unsteady Aerodynamic Characteristics of Oscillating Transonic Cascade

2003 ◽  
Author(s):  
Mizuho Aotsuka ◽  
Toshinori Watanabe ◽  
Yasuo Machina
Keyword(s):  
Boundary Layer ◽  
Pressure Fluctuations ◽  
Boundary Layer Separation ◽  
Aerodynamic Characteristics ◽  
Compressor Cascade ◽  
Layer Interaction ◽  
Unsteady Aerodynamic ◽  
Shock Boundary Layer Interaction ◽  
Boundary Layer Interaction ◽  
Shock Oscillation

The unsteady aerodynamic characteristics of an oscillating compressor cascade composed of Double-Circular-Arc airfoil blades were both experimentally and numerically studied under transonic flow conditions. The study aimed at clarifying the role of shock waves and boundary layer separation due to the shock boundary layer interaction on the vibration characteristics of the blades. The measurement of the unsteady aerodynamic moment on the blades was conducted in a transonic linear cascade tunnel using an influence coefficient method. The cascade was composed of seven DCA blades, the central one of which was an oscillating blade in a pitching mode. The unsteady moment was measured on the central blade as well as the two neighboring blades. The behavior of the shock waves was visualized through a schlieren technique. A quasi-three dimensional Navier-Stokes code was developed for the present numerical simulation of the unsteady flow fields around the oscillating blades. A k-ε turbulence model was utilized to adequately simulate the flow separation phenomena caused by the shock-boundary layer interaction. The experimental and numerical results complemented each other and enabled a detailed understanding of the unsteady aerodynamic behavior of the cascade. It was found that the surface pressure fluctuations induced by the shock oscillation were the governing factor for the unsteady aerodynamic moment acting on the blades. Such pressure fluctuations were primarily induced by the movement of impingement point of the shock on the blade surface. During the shock oscillation the separated region caused by the shock boundary layer interaction also oscillated along the blade surface, and induced additional pressure fluctuations. The shock oscillation and the movement of the separated region were found to play the principal role in the unsteady aerodynamic and vibration characteristics of the transonic compressor cascade.

Shock regularization in dense gases by viscous–inviscid interactions

2010 ◽  
Vol 644 ◽  
pp. 473-507 ◽  
Author(s):  
A. KLUWICK ◽  
G. MEYER
Keyword(s):  
Boundary Layer ◽  
Strong Shock ◽  
Laminar Flows ◽  
Interaction Region ◽  
Inviscid Flows ◽  
Layer Interaction ◽  
Dense Gases ◽  
Shock Boundary Layer Interaction ◽  
Internal Shock ◽  
Boundary Layer Interaction

Transonic high-Reynolds-number flows through channels which are so narrow that the classical boundary-layer approach fails locally are considered in the presence of a weak stationary normal shock. As a consequence, the properties of the inviscid core and the viscosity-dominated boundary-layer region can no longer be determined in subsequent steps but have to be calculated simultaneously in a small interaction region. Under the requirement that the core-region flow should be considered to be one-dimensional to the leading order the resulting problem of shock–boundary-layer interaction is formulated by the means of matched asymptotic expansions for laminar flows of dense gases (Bethe–Zel'dovich–Thompson, or BZT, fluids). Such fluids have the distinguishing feature that the fundamental derivative of gas dynamics can become negative or even change sign under the thermodynamic conditions to be considered. The regularizing properties of the mechanism of viscous–inviscid interactions on the different anomalous shock forms possible in the flow of dense gases with mixed nonlinearity, namely rarefaction, sonic, double-sonic and split shocks, will be discussed. To this end we show the consistency of the resulting internal-shock profiles because of strong shock–boundary-layer interaction with a generalized shock admissibility criterion formulated for the case of purely inviscid flows. Representative solutions for the internal-shock structures are presented, and the importance of such flow phenomena in technical applications in the near future are shortly discussed by considering estimates of the actual dimensions of the interaction region for a specific representative situation in which the BZT fluid PP10 (C13F22) has been selected.

Experimental Study on Pressure Fluctuations in the Shock/boundary Layer Interaction of an Axisymmetric Body

2011 ◽  
Vol 66-68 ◽  
pp. 1483-1487
Author(s):  
Hong Xiao ◽  
Chao Gao ◽  
Zhen Kun Ma
Keyword(s):  
Boundary Layer ◽  
Mach Number ◽  
Dynamic Pressure ◽  
Pressure Fluctuations ◽  
Low Frequency ◽  
Axisymmetric Body ◽  
Fluctuating Pressure ◽  
Layer Interaction ◽  
Shock Boundary Layer Interaction ◽  
Boundary Layer Interaction

The characteristics of the fluctuating pressure for the 15° expansion corner of an axisymmetric body have been investigated experimentally using dynamic pressure measurements and Schlieren photograghs. Data were acquired over a Mach number ranging from 0.8 to 0.92. The angles of attack ranged from 0° to 5°. Pressure signals were measured simultaneously in several positions along the axis of model and were analyzed both in the time and frequency domains. The results indicate that large fluctuating pressure loads, resulting from the shock/boundary layer interaction exist at the transonic flow condition, because of the shock/boundary layer interaction. The maximal pressure fluctuation occurs after the expansion corner at Mach number 0.86. With the Mach number increasing, the position of the normal shock moves downstream. In the shock/boundary layer interaction region, the fluctuating pressure changes significantly with different angles of attack. Moreover, this interaction has a main effect of enhancing the power spectral density in low-frequency range (f≤5KHz).

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