High alpha aerodynamic control by tangential fuselage blowing
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Font, G. I.↗
Engineering topics
Tavella, D. A.
Publications and source records attributed to Tavella, D. A..
Two blowing concepts for roll and lateral control of aircraft
Two schemes to modulate aerodynamic forces for roll and lateral control of aircraft have been investigated. The first scheme, called the lateral blowing concept, consists of thin jets of air exiting spanwise, or at small angle with the spanwise direction, from slots at the tips of straight wings. For this scheme, in addition to experimental measurements, a theory was developed showing the analytical relationship between aerodynamic forces and jet and wing parameters. Experimental results confirmed the theoretically derived scaling laws. The second scheme, which was studied experimentally, is called the jet spoiler concept and consists of thin jets exiting normally to the wing surface from slots aligned with the spanwise direction.
Tavella, D. A.↗
Analysis of interacting dual lifting ejector systems
An analytical treatment is presented for a flowfield generated by a pair of interacting, two-dimensional parallel jets, representative of the two exhaust streams issuing from the thrust augmentor nozzles of dual lifting jet VTOL aircraft propulsion systems. Predictions of the analysis for the ratio of primary to secondary velocity are in close agreement with experimentally observed values, if the spreading rate parameter is allowed to assume a value greater than that which applies to a free jet. Theoretical results are combined with existing experimental data for unventilated jets, in order to arrive at an estimate of the thrust augmentation produced by a jet pair with an arbitrary degree of ventilation.
Lund, T. S.↗
The lift of sharp-leading-edged delta wings with blowing
An analysis of the lift augmentation due to a thin jet of air issuing from a slot along the leading edge of a delta wing is presented. The problem is treated with an extension of the method of Brown and Michael, representing the separated flow on the lee side of the wing by a pair of concentrated vortices and corresponding feeding sheets. It is assumed that the jet is not affected by Coanda forces. The analysis produces qualitative agreement with experiments.
Tavella, D. A.↗
A zonal computational procedure adapted to the optimization of two-dimensional thrust augmentor inlets
A viscous-inviscid interaction methodology based on a zonal description of the flowfield is developed as a mean of predicting the performance of two-dimensional thrust augmenting ejectors. An inviscid zone comprising the irrotational flow about the device is patched together with a viscous zone containing the turbulent mixing flow. The inviscid region is computed by a higher order panel method, while an integral method is used for the description of the viscous part. A non-linear, constrained optimization study is undertaken for the design of the inlet region. In this study, the viscous-inviscid analysis is complemented with a boundary layer calculation to account for flow separation from the walls of the inlet region. The thrust-based Reynolds number as well as the free stream velocity are shown to be important parameters in the design of a thrust augmentor inlet.
Lund, T. S.↗
Viscous-inviscid aerodynamic analysis of two-dimensional thrust augmentors
A theory for the computation of two-dimensional thrust augmentor performance is developed. The flow field is assumed to be incompressible, of uniform density and statistically steady. The flow in and around the augmentor is assumed to consist of an outer, inviscid part and an inner, viscous part. The outer field is calculated analytically and then matched with the inner, viscous field, which is computed by means of integral methods. This form of analysis leads to a simple and economical approach, particularly useful for conducting parametric studies. The theoretical results are compared with recently acquired experimental data.
Tavella, D. A.↗
Some observations on the aerodynamics of an airfoil with a jet exhausting from the lower surface
A preliminary investigation was carried out to study the aerodynamics of an 18% symmetrical airfoil with a rectangular jet exhausting from the lower surface. Static pressures on the airfoil surface and total pressures in the near wake were measured at jet momentum coefficients ranging from 0 to 2. Results from these measurements were used to study the effects of a jet-cross flow interaction on the aerodynamics of an airfoil. These results were also compared with those obtained from a two-dimensional inviscid theoretical model. Measurements indicate positive and negative pressure regions in front of and behind the jet respectively. The intensity of the pressure in these regions increases with increasing jet strength. Upper surface pressures also decrease due to an effective angle of attack induced by the jet-cross flow interaction. The pressure variations on the upper and lower surfaces induce a positive sectional lift coefficient on the airfoil. The magnitude of the lift coefficient for a given momentum coefficient decreases with decreasing aspect ratio of the nozzle.
Leopold, D.↗
Aerodynamics of an airfoil with a jet issuing from its surface
A simple, two dimensional, incompressible and inviscid model for the problem posed by a two dimensional wing with a jet issuing from its lower surface is considered and a parametric analysis is carried out to observe how the aerodynamic characteristics depend on the different parameters. The mathematical problem constitutes a boundary value problem where the position of part of the boundary is not known a priori. A nonlinear optimization approach was used to solve the problem, and the analysis reveals interesting characteristics that may help to better understand the physics involved in more complex situations in connection with high lift systems.
Tavella, D. A.↗