Induced drag of wings in ground effect

2016 ◽  
Vol 120 (1234) ◽  
pp. 1867-1890 ◽  
Author(s):  
P.J. Mantle
Keyword(s):  
Aspect Ratio ◽  
Closed Form ◽  
Original Work ◽  
Ground Effect ◽  
Air Gap ◽  
Closed Form Solutions ◽  
End Plate ◽  
Induced Drag ◽  
Lift And Drag ◽  
Good Agreement

ABSTRACTThis paper provides a set of closed form solutions for the lift and drag of wings flying in ground effect both with and without end plates. The developed theories are based on observations of several independent sources of controlled model tests over ground planes and over water and on previous theories prepared by researchers from the original work by Prandtl and Wieselsberger to the present day. The theories developed cover wings of varying aspect ratio, thickness to chord ratios and angle of attack. The results for wings with end plates include the effect of ground (or surface) clearance height, end plate depth and air gap depths beneath the wings or end plates. Good agreement is found between the developed theory and test.

Force and Moment Measurements of Supercavitating Hydrofoils of Finite Span With Comparison to Theory

1975 ◽  
Vol 97 (4) ◽  
pp. 453-462
Author(s):  
P. Leehey ◽  
T. S. Stellinger
Keyword(s):  
Aspect Ratio ◽  
Asymptotic Expansions ◽  
Cavity Length ◽  
Large Aspect Ratio ◽  
Drag Coefficients ◽  
Finite Span ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Lift And Drag ◽  
Good Agreement

Measurements were made of lift, drag, and moment coefficients, and cavity length for aspect ratio 3 and 5 supercavitating hydrofoils of elliptical planform. These measurements are compared with theoretical predictions obtained from matching asymptotic expansions for large aspect ratio. Good agreement was obtained for lift and drag coefficients for angles of attack from 10 deg to 15 deg and for a wide range of cavity lengths. Theoretical moment coefficients were too large indicating the need for lifting surface corrections.

Faraday instability threshold in large-aspect-ratio containers

2002 ◽  
Vol 467 ◽  
pp. 307-330 ◽  
Author(s):  
FRANCISCO J. MANCEBO ◽  
JOSÉ M. VEGA
Keyword(s):  
Aspect Ratio ◽  
Numerical Solution ◽  
Closed Form ◽  
Ad Hoc ◽  
Linear Problem ◽  
Experimental Results ◽  
Large Aspect Ratio ◽  
Faraday Waves ◽  
Closed Form Solutions ◽  
Faraday Instability

We consider the Floquet linear problem giving the threshold acceleration for the appearance of Faraday waves in large-aspect-ratio containers, without further restrictions on the values of the parameters. We classify all distinguished limits for varying values of the various parameters and simplify the exact problem in each limit. The resulting simplified problems either admit closed-form solutions or are solved numerically by the well-known method introduced by Kumar & Tuckerman (1994). Some comparisons are made with (a) the numerical solution of the original exact problem, (b) some ad hoc approximations in the literature, and (c) some experimental results.

Closed-Form Solutions for Eigenbuckling of Rectangular Mindlin Plate

2016 ◽  
Vol 16 (08) ◽  
pp. 1550079 ◽  
Author(s):  
Yufeng Xing ◽  
Wei Xiang
Keyword(s):  
Closed Form ◽  
Present Method ◽  
Separation Of Variables ◽  
Mindlin Plate ◽  
Rectangular Plates ◽  
Closed Form Solutions ◽  
Simply Supported ◽  
Major Development ◽  
First Time ◽  
Good Agreement

This paper studies the eigenbuckling of Mindlin plate with two adjacent edges clamped and the remaining edges simply supported or clamped by using the separation of variables method, and the concise and explicit closed-form solutions are obtained for the first time. The cases involving free edges can also be dealt with if there are two opposite edges simply supported. The closed-form solutions are in good agreement with the existing solutions, thus the validity of present method and accuracy of the obtained solutions are verified. This paper proves to be a major development of analytical method since it has long been acknowledged that the eigenbuckling of rectangular plates without two parallel edges simply supported are not amenable to analytical solutions.

Modeling perforates in mufflers using two-ports

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
T. Elnady ◽  
M. Åbom ◽  
S. Allam
Keyword(s):  
Closed Form ◽  
Closed Form Solutions ◽  
Analysis Techniques ◽  
Segmentation Approach ◽  
Simulation Results ◽  
Number Of Segments ◽  
Good Agreement

One of the main sources of noise of a vehicle is the engine where its noise is usually damped by means of acoustic mufflers. A very common problem in the modeling of automotive mufflers is that of two flow ducts coupled through a perforate. A new segmentation approach is developed here based on two-port analysis techniques, in order to model perforated pipes using general two-port codes, which are widely available. Examples are given for simple muffler configurations and the convergence of the technique is investigated based on the number of segments used. The results are compared with closed form solutions form the literature. Finally, an analysis of a complicated multichamber perforated muffler system is presented. The two-port simulation results show good agreement with both the measurements, and the simulations using the classical four-port elements.

Bond-Slip Relationship for EB-FRP Joints by Including Free End Slip

2013 ◽  
Vol 368-370 ◽  
pp. 1031-1038
Author(s):  
Kang Liu
Keyword(s):  
Closed Form ◽  
Response Curve ◽  
Experimental Results ◽  
Identification Procedure ◽  
Bond Slip ◽  
Closed Form Solutions ◽  
Theoretical Results ◽  
Good Agreement

Closed form solutions are derived in this work by including free end slip, relating free end and loaded end slips to bond resistance, as well as relating slip or strain at any position to free end slip. To identify the bond-slip relationship, indirect analytical identification from load-slip response curve is used. Using the identification procedure developed in this paper, very good agreement between the theoretical solutions and experimental results was observed, which validates the theoretical results derived in this work.

Closed Form Solutions of Joint Water-Filling for Coordinated Transmission

2010 ◽  
Vol E93-B (12) ◽  
pp. 3461-3468 ◽  
Author(s):  
Bing LUO ◽  
Qimei CUI ◽  
Hui WANG ◽  
Xiaofeng TAO ◽  
Ping ZHANG
Keyword(s):  
Closed Form ◽  
Closed Form Solutions ◽  
Water Filling
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