Geometrical Scaling Effects on Supersonic Inlet Performance

2017 ◽  
Author(s):  
Rasoul Askari ◽  
Mohammad Reza Soltani ◽  
Afshin Khajeh Fard
Keyword(s):  
Mach Number ◽  
Interface Plane ◽  
Scaling Effects ◽  
Mean Flow ◽  
Flow Distortion ◽  
External Compression ◽  
Inlet Flow ◽  
Static Pressure Distribution ◽  
Supersonic Inlet ◽  
Geometrical Scaling

The effects of geometrical scaling on a supersonic external compression axisymmetric inlet are investigated. Various lower and higher geometrical scales of supersonic inlet are considered as the case studies. The inlet flow is simulated numerically using RANS solver along with the SST k-w turbulence model. The numerical results are in an acceptable agreement with the NACA experimental data at free stream Mach number of 1.79 and at zero angle of attack. The results show that the static pressure distribution of the inlet flow experiences some differences for various scales especially at the regions of the flow entrance and throat area. The mean flow Mach number and the mass flow rate at the Aerodynamic Interface Plane (AIP) increases with increasing the inlet scaling. The increasing of inlet geometrical scale results in an increase in the pressure recovery. However there is no sensitive variation on the flow distortion.

scholarly journals Effect of BLI–Type Inlet Distortion on Turbofan Engine Performance

2014 ◽  
Author(s):  
James R. Lucas ◽  
Walter F. O’Brien ◽  
Anthony M. Ferrar
Keyword(s):  
Boundary Layer ◽  
Engine Performance ◽  
Wire Mesh ◽  
System Level ◽  
Interface Plane ◽  
Flow Profile ◽  
Low Velocity ◽  
Flow Distortion ◽  
Inlet Flow ◽  
Turbofan Engine

Boundary Layer Ingestion (BLI) is currently being researched as a potential method to improve efficiency and decrease emissions for the next generation of commercial aircraft. While re-energizing the boundary layer formed over the fuselage of an aircraft has many system level benefits, ingesting the low velocity boundary layer flow through a serpentine inlet into a turbofan engine adversely affects the performance of the engine. This work reports an experimental investigation of the effects of a BLI-type distortion on a turbofan engine’s performance. A modified JT15D-1 turbofan engine was used in this study. Inlet flow distortion was created by a layered wire mesh distortion screen designed to create a total pressure distortion profile at the aerodynamic interface plane (AIP) similar to NASA’s Inlet A boundary layer ingesting inlet flow profile. Results of this investigation showed a 15.5% decrease in stream thrust and a 14% increase in TSFC in the presence of BLI-type distortion. The presence of the distortion screen resulted in a 24% increase in mass-averaged entropy production along the entire fan flow path compared to the non-distorted test.

Mach number effects on the global mixing modes induced by ramp injectors in supersonic flows

2014 ◽  
Vol 757 ◽  
pp. 403-431 ◽  
Author(s):  
Luca Massa
Keyword(s):  
Mach Number ◽  
Free Stream ◽  
Mixing Layer ◽  
Three Dimensional ◽  
Base Flow ◽  
Recirculation Region ◽  
Mean Flow ◽  
Mixing Rate ◽  
Flow Distortion ◽  
The Mean

AbstractModern injectors for supersonic combustors (hypermixers) augment the fuel–air mixing rate by energizing the perturbation in the mixing layer. From an instability point of view, the increased perturbation growth is linked to the increased complexity of the equilibrium base flow when compared to the axisymmetric mixing layer. Common added features are streamwise vortex streaks, oblique recompression shocks and Prandtl–Meyer expansions. One of the main effects of such distortions of the mean flow is to transform the instability responsible for the creation of fine scales from a local amplified mode to a global self-sustained fluctuation. The focus of the present research is on the flow distortion induced by flushed ramps for free-stream Mach numbers in the range 2.5–3.5. The principal mean flow features are the recirculation region due to the recompression of the flow after the ramp, the shear layer over the recirculation region and the vortex streaks propagating from the ramp corners. A global three-dimensional stability analysis and three-dimensional direct numerical simulations of small perturbations of the mean flow are performed. The growth and energy distribution of the dominant and subdominant fluctuations supported by the three-dimensional steady laminar base flow are computed. The main results are the growth rates of the self-sustained varicose and sinuous modes and their correlation to the variation in the free-stream Mach number. The complex three-dimensional wavemaker is investigated by evaluating the three-dimensional eigenfunctions of the direct and adjoint modes, and the effects of the axial vorticity generated by the ramp corners are discussed.

Inlet Flow Distortion in Turbomachinery

1980 ◽  
Vol 102 (4) ◽  
pp. 924-929
Author(s):  
B. S. Seidel ◽  
M. D. Matwey ◽  
J. J. Adamczyk
Keyword(s):  
Mach Number ◽  
Axial Compressor ◽  
Stagnation Pressure ◽  
Single Stage ◽  
Parameter Study ◽  
Stagnation Temperature ◽  
Flow Distortion ◽  
Inlet Flow ◽  
Swirl Angle ◽  
Mach Numbers

A single stage axial compressor with distorted inflow is studied. The inflow distortion occurs far upstream and may be a distortion in stagnation temperature, stagnation pressure or both. The blade rows are modelled as semi-actuator disks. Losses, quasi-steady deviation angles, and reference incidence correlations are included in the analysis. Both subsonic and transonic relative Mach Numbers are considered. A parameter study is made to determine the influence of such variables as Mach Number and swirl angle on the attenuation of the distortion.

scholarly journals Influence of the Atmospheric Surface Layer on a Turbulent Flow Downstream of a Ship Superstructure

2013 ◽  
Vol 30 (8) ◽  
pp. 1803-1819 ◽  
Author(s):  
Luksa Luznik ◽  
Cody J. Brownell ◽  
Murray R. Snyder ◽  
Hyung Suk Kang
Keyword(s):  
Surface Layer ◽  
Atmospheric Surface Layer ◽  
The United States ◽  
Naval Academy ◽  
Mean Flow ◽  
Flow Distortion ◽  
Turbulent Statistics ◽  
Sonic Anemometers ◽  
Flight Deck ◽  
Inflow Conditions

Abstract This paper describes a set of turbulence measurements at sea in the area of high flow distortion in the near-wake and recirculation zone behind a ship's superstructure that is similar in geometry to a helicopter hangar/flight deck arrangement found on many modern U.S. Navy ships. The instrumented ship is a 32-m-long training vessel operated by the United States Naval Academy that has been modified by adding a representative flight deck and hangar structure. The flight deck is instrumented with up to seven sonic anemometers/thermometers that are used to obtain simultaneous velocity measurements at various spatial locations on the flight deck, and one sonic anemometer at bow mast is used to characterize inflow atmospheric boundary conditions. Data characterizing wind over the deck at an incoming angle of 0° (head winds) and wind speeds from 2 to 10 m s−1 obtained in the Chesapeake Bay are presented and discussed. Turbulent statistics of inflow conditions are analyzed using the Kaimal universal turbulence spectral model for the atmospheric surface layer and show that for the present dataset this approach eliminates the need to account for platform motion in computing variances and covariances. Conditional sampling of mean flow and turbulence statistics at the flight deck indicate no statistically significant variations between unstable, stable, and neutral atmospheric inflow conditions, and the results agree with the published data for flows over the backward-facing step geometries.

scholarly journals Investigation of Flows in Rectangular Diffusers With Inlet Flow Distortion

1982 ◽  
Author(s):  
M. M. Al-Mudhafar ◽  
M. Ilyas ◽  
F. S. Bhinder
Keyword(s):  
Experimental Study ◽  
Velocity Profiles ◽  
Pressure Recovery ◽  
Two Dimensional ◽  
Flow Distortion ◽  
Inlet Flow ◽  
Inlet Velocity ◽  
Inlet Distortion ◽  
Mach Numbers ◽  
Inlet Flow Distortion

The results of an experimental study on the influence of severely distorted velocity profiles on the performance of a straight two-dimensional diffuser are reported. The data cover entry Mach numbers ranging from 0.1 to 0.6 and several inlet distortion levels. The pressure recovery progressively deteriorates as the inlet velocity is distorted.

The Effect of Non-Uniform Aerodynamic Loading on the Blade Responses

2007 ◽  
Author(s):  
Abdelgadir M. Mahmoud ◽  
Mohd S. Leong
Keyword(s):  
Turbine Blades ◽  
Forced Response ◽  
Flow Section ◽  
Flow Distortion ◽  
Inlet Flow ◽  
Bladed Disk ◽  
Aerodynamic Loading ◽  
Bladed Disk Assembly ◽  
Flow Generator ◽  
Inlet Flow Distortion

Turbine blades are always subjected to severe aerodynamic loading. The aerodynamic loading is uniform and Of harmonic nature. The harmonic nature depends on the rotor speed and number of nozzles (vanes counts). This harmonic loading is the main sources responsible for blade excitation. In some circumstances, the aerodynamic loading is not uniform and varies circumferentially. This paper discussed the effect of the non-uniform aerodynamic loading on the blade vibrational responses. The work involved the experimental study of forced response amplitude of model blades due to inlet flow distortion in the presence of airflow. This controlled inlet flow distortion therefore represents a nearly realistic environment involving rotating blades in the presence of airflow. A test rig was fabricated consisting of a rotating bladed disk assembly, an inlet flow section (where flow could be controlled or distorted in an incremental manner), flow conditioning module and an aerodynamic flow generator (air suction module with an intake fan) for investigations under laboratory conditions. Tests were undertaken for a combination of different air-flow velocities and blade rotational speeds. The experimental results showed that when the blades were subjected to unsteady aerodynamic loading, the responses of the blades increased and new frequencies were excited. The magnitude of the responses and the responses that corresponding to these new excited frequencies increased with the increase in the airflow velocity. Moreover, as the flow velocity increased the number of the newly excited frequency increased.

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