Comparison of Boundary-Layer Transition Predictions Using Flight Test Data

1998 ◽  
Vol 35 (6) ◽  
pp. 891-897 ◽  
Author(s):  
Geza Schrauf ◽  
Jean Perraud ◽  
Domenico Vitiello ◽  
Fung Lam
Keyword(s):  
Boundary Layer ◽  
Test Data ◽  
Flight Test ◽  
Boundary Layer Transition ◽  
Layer Transition

The Flight Testing of Natural and Hybrid Laminar Flow Nacelles

1994 ◽  
Author(s):  
Brian Barry ◽  
Simon J. Parke ◽  
Nicholas W. Bown ◽  
Hansgeorg Riedel ◽  
Martin Sitzmann
Keyword(s):  
Boundary Layer ◽  
Laminar Flow ◽  
Aircraft Engine ◽  
Flight Test ◽  
Boundary Layer Transition ◽  
Future Application ◽  
Flight Testing ◽  
Layer Transition ◽  
Suction System ◽  
Natural Laminar Flow

The achievement of large areas of laminar flow over aircraft engine nacelles offers significant savings in aircraft fuel consumption. Based upon current engine configurations nett sfc benefits of up to 2% are possible. In addition the engine nacelle is ideally suited to the early inclusion of laminar flow technology, being relatively self contained with the possibility of application to existing airframes. In September 1992 a European Consortium managed by Rolls-Royce including MTU and DLR began flight testing of a natural laminar flow nacelle. This programme was later extended by R-R and DLR to flight test a hybrid laminar flow nacelle featuring boundary layer suction and insect contamination protection. The tests evaluated the effects of flight and engine environment, boundary layer transition phenomena, suction system operation and insect contamination avoidance strategies. This paper describes the global conclusions from these flight tests which are a significant milestone leading to the future application of laminar flow technology to engine nacelles.

A New Approach to the Reduction of Pump Cavitation: The Hubless Inducer

1967 ◽  
Vol 89 (1) ◽  
pp. 125-136
Author(s):  
W. K. Jekat
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Temperature Effect ◽  
Test Data ◽  
Special Form ◽  
Boundary Layer Transition ◽  
Theoretical Equation ◽  
Layer Transition ◽  
New Approach ◽  
Specific Speed

This paper describes a new and promising inducer which has no hub but a shroud. The design makes it possible to employ drastic vane sweepback. The shroud eliminates the vane clearance cavitation observed in the conventional screw inducer. Test data, cavitation photographs, and an analysis are presented. Maximum suction specific speed reached was 55,000 with 153 F water. Suction specific speed increases with speed and temperature up to a point. A special form of Reynolds number correlates the speed and temperature effect. The possible interrelation of boundary-layer transition and cavitation is discussed. Best suction specific speeds occur at positive incidence angles. The concept of incidence head is introduced and a theoretical equation is given.

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