Pub Date : 1996-02-01DOI: 10.1017/S0001924000027329
R. Clements
{"title":"Mathematical Analysis in Engineering: How to Use the Basic Tools , C.C. Mei, Cambridge University Press, The Pitt Building, Trumpington Street, Cambridge CB2 IRP. 1995. 461pp. Illustrated. £45.","authors":"R. Clements","doi":"10.1017/S0001924000027329","DOIUrl":"https://doi.org/10.1017/S0001924000027329","url":null,"abstract":"","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":"29 1","pages":"77-77"},"PeriodicalIF":1.4,"publicationDate":"1996-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89759088","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-11-01DOI: 10.1017/S0001924000028670
B. N. Nield
Abstract The process of designing the Boeing 777 high lift system is described. Particular attention is given to design constraints and examples are given of the trade studies completed. The theoretical design tools and experimental test program are described. A survey of the high lift elements is presented and flight test results are compared with predictions.
{"title":"An overview of the Boeing 777 high lift aerodynamic design","authors":"B. N. Nield","doi":"10.1017/S0001924000028670","DOIUrl":"https://doi.org/10.1017/S0001924000028670","url":null,"abstract":"Abstract The process of designing the Boeing 777 high lift system is described. Particular attention is given to design constraints and examples are given of the trade studies completed. The theoretical design tools and experimental test program are described. A survey of the high lift elements is presented and flight test results are compared with predictions.","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":"99 1","pages":"361 - 371"},"PeriodicalIF":1.4,"publicationDate":"1995-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1017/S0001924000028670","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57253439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-05-01DOI: 10.1017/S0001924000028360
A. R. Moore, M. V. Lowson
Abstract An experimental investigation has been made into the effects of riblets on the drag in a rectangular duct of aspect ratio 10. It has been found that a maximum drag reduction of approximately 10% occurs in fully developed turbulent flow. This figure is larger than the 6–8% drag reduction usually found for external flow. The maximum drag reduction occurred when the height of the riblets was between 7 and 13 wall units. Analysis of the developing region of the flow has shown a maximum drag reduction of approximately 8% at a wall unit value of 13, consistent with results in external flows. The effects of riblets on transition has also been investigated. It was found that riblets delayed transition by 2–4% in critical Re as measured by peak flatness, and caused some extension in the length of the transition process, so that the completion of transition was delayed by between 4–8%, with the stronger effect at the lower Reynolds numbers.
{"title":"Drag reduction in a rectangular duct using riblets","authors":"A. R. Moore, M. V. Lowson","doi":"10.1017/S0001924000028360","DOIUrl":"https://doi.org/10.1017/S0001924000028360","url":null,"abstract":"Abstract An experimental investigation has been made into the effects of riblets on the drag in a rectangular duct of aspect ratio 10. It has been found that a maximum drag reduction of approximately 10% occurs in fully developed turbulent flow. This figure is larger than the 6–8% drag reduction usually found for external flow. The maximum drag reduction occurred when the height of the riblets was between 7 and 13 wall units. Analysis of the developing region of the flow has shown a maximum drag reduction of approximately 8% at a wall unit value of 13, consistent with results in external flows. The effects of riblets on transition has also been investigated. It was found that riblets delayed transition by 2–4% in critical Re as measured by peak flatness, and caused some extension in the length of the transition process, so that the completion of transition was delayed by between 4–8%, with the stronger effect at the lower Reynolds numbers.","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":"99 1","pages":"187 - 193"},"PeriodicalIF":1.4,"publicationDate":"1995-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1017/S0001924000028360","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57253390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-02-01DOI: 10.1017/S0001924000028165
M. Khalid
Summary The dynamic stability derivatives of blunt cones for small variations in angles of attack have been previously derived by the current author. However, no account of the unsteady nature of the boundary layer was made in that work. In this paper closed form expressions for the increment in dynamic stability due to the presence of the boundary layer are derived by considering the pressure distribution perturbations as the boundary layer continuously adjusts to the enclosed oscillating body. The theory provides a first hand estimate of the complete pitch derivative damping without having to resort to more rigorous and expensive computational methods. Calculations performed at Mach numbers of 7 to 10 with axis positions ranging from 0·5 to 0·7 of the chord length for cones of semi-angle 10° and 20°, indicate that the effect of boundary layer is to slightly reduce the magnitude of the inviscid damping derivative. For blunt cones at angles of attack less than 5°, this was in good agreement with the limited experimental data available.
{"title":"Viscous contribution to the high Mach number damping in pitch of blunt slender cones at small angles of attack","authors":"M. Khalid","doi":"10.1017/S0001924000028165","DOIUrl":"https://doi.org/10.1017/S0001924000028165","url":null,"abstract":"Summary The dynamic stability derivatives of blunt cones for small variations in angles of attack have been previously derived by the current author. However, no account of the unsteady nature of the boundary layer was made in that work. In this paper closed form expressions for the increment in dynamic stability due to the presence of the boundary layer are derived by considering the pressure distribution perturbations as the boundary layer continuously adjusts to the enclosed oscillating body. The theory provides a first hand estimate of the complete pitch derivative damping without having to resort to more rigorous and expensive computational methods. Calculations performed at Mach numbers of 7 to 10 with axis positions ranging from 0·5 to 0·7 of the chord length for cones of semi-angle 10° and 20°, indicate that the effect of boundary layer is to slightly reduce the magnitude of the inviscid damping derivative. For blunt cones at angles of attack less than 5°, this was in good agreement with the limited experimental data available.","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":"99 1","pages":"69 - 74"},"PeriodicalIF":1.4,"publicationDate":"1995-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57253704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1995-01-01DOI: 10.1017/S0001924000096652
M. Ö. Çarpinlioglu, Ö. T. Göksel
Abstract The influence of isolated spherical roughness elements upon the transition of a three-dimensional boundary layer on a swept flat plate is discussed in this paper. Perturbations induced by the roughness are found to be more effective on the start of transition rather than the crossflow of the laminar undisturbed boundary layer at the roughness location.
{"title":"Effect of spherical roughness elements upon transition of a 3-D boundary layer","authors":"M. Ö. Çarpinlioglu, Ö. T. Göksel","doi":"10.1017/S0001924000096652","DOIUrl":"https://doi.org/10.1017/S0001924000096652","url":null,"abstract":"Abstract The influence of isolated spherical roughness elements upon the transition of a three-dimensional boundary layer on a swept flat plate is discussed in this paper. Perturbations induced by the roughness are found to be more effective on the start of transition rather than the crossflow of the laminar undisturbed boundary layer at the roughness location.","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":"99 1","pages":"26 - 28"},"PeriodicalIF":1.4,"publicationDate":"1995-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57256129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1994-07-01DOI: 10.1017/S0001924000049757
M. F. Zedan
Abstract The performance of axial line singularity methods has been investigated systematically for various solution parameters using carefully chosen test cases. The results indicate that increasing the number of elements and using stretched node distribution improves the solution accuracy until the matrix becomes near-singular. The matrix condition number increases with these parameters as well as with the order of intensity variation and profile thickness. For moderate fineness ratios, the linear methods outperform zero-order methods. The linear doublet method performs best with control points at the x-locations of nodes while the source methods perform best with control points mid-way between nodes. The doublet method has a condition number an order of magnitude lower than the source method and generally provides more accurate results and handles a wider range of bodies. With appropriate solution parameters, the method provides excellent accuracy for bodies without slope discontinuity. The smoothing technique proposed recently by Hemsch has been shown to reduce the condition number of the matrix; however it should be used with caution. It is recommended to use it only when the solution is highly oscillatory with a near-singular matrix. A criterion for the optimum value of the smoothing parameter is proposed.
{"title":"Tuning the axial singularity method for accurate calculation of potential flow around axisymmetric bodies","authors":"M. F. Zedan","doi":"10.1017/S0001924000049757","DOIUrl":"https://doi.org/10.1017/S0001924000049757","url":null,"abstract":"Abstract The performance of axial line singularity methods has been investigated systematically for various solution parameters using carefully chosen test cases. The results indicate that increasing the number of elements and using stretched node distribution improves the solution accuracy until the matrix becomes near-singular. The matrix condition number increases with these parameters as well as with the order of intensity variation and profile thickness. For moderate fineness ratios, the linear methods outperform zero-order methods. The linear doublet method performs best with control points at the x-locations of nodes while the source methods perform best with control points mid-way between nodes. The doublet method has a condition number an order of magnitude lower than the source method and generally provides more accurate results and handles a wider range of bodies. With appropriate solution parameters, the method provides excellent accuracy for bodies without slope discontinuity. The smoothing technique proposed recently by Hemsch has been shown to reduce the condition number of the matrix; however it should be used with caution. It is recommended to use it only when the solution is highly oscillatory with a near-singular matrix. A criterion for the optimum value of the smoothing parameter is proposed.","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":"98 1","pages":"215 - 226"},"PeriodicalIF":1.4,"publicationDate":"1994-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1017/S0001924000049757","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57253926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1990-10-01DOI: 10.1017/S0001924000023101
G. De Matteis
Abstract A general dynamic model of the hang glider is applied to the analysis of response to control. The transfer functions of the glider to the longitudinal and lateral controls are formulated and some significant results, in terms of frequency response are presented and discussed. The relevant effects of the unsteady aerodynamics on the dynamics of the system are shown and the characteristics of poor lateral control are confirmed as observed in flight.
{"title":"Response of hang gliders to control","authors":"G. De Matteis","doi":"10.1017/S0001924000023101","DOIUrl":"https://doi.org/10.1017/S0001924000023101","url":null,"abstract":"Abstract A general dynamic model of the hang glider is applied to the analysis of response to control. The transfer functions of the glider to the longitudinal and lateral controls are formulated and some significant results, in terms of frequency response are presented and discussed. The relevant effects of the unsteady aerodynamics on the dynamics of the system are shown and the characteristics of poor lateral control are confirmed as observed in flight.","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":"94 1","pages":"289 - 294"},"PeriodicalIF":1.4,"publicationDate":"1990-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57253098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1990-01-01DOI: 10.1017/S0001924000022326
R. C. Lock
Summary A review is given of current methods in theoretical aerodynamics which are useful in the design of aircraft wings for subsonic and transonic speeds. These are of two basic types: (A) direct methods for calculating the flow over a givenwing shape. In the design process, these can be used to obtain a rapid estimate of the effect of a specified change in wing shape. The most practical methods of this type make use of the viscous/inviscid interaction technique; some recent methods are described and examples are given of their use, both in two and three dimensions, including comparisons with experiment. (B) inverse methods in which the shape is calculated explicitly, as a result of either (a) specifying the surface pressure distribution on the wing, or (b) requiring that some suitable ‘target’ function, usually the drag/lift ratio, shall be a minimum. At present, these methods are restricted to inviscid flow. Several examples of both ‘pressure’ and ‘optimisation’ methods are discussed, and their advantages and limitations considered.
{"title":"Aerodynamic design methods for transonic wings","authors":"R. C. Lock","doi":"10.1017/S0001924000022326","DOIUrl":"https://doi.org/10.1017/S0001924000022326","url":null,"abstract":"Summary A review is given of current methods in theoretical aerodynamics which are useful in the design of aircraft wings for subsonic and transonic speeds. These are of two basic types: (A) direct methods for calculating the flow over a givenwing shape. In the design process, these can be used to obtain a rapid estimate of the effect of a specified change in wing shape. The most practical methods of this type make use of the viscous/inviscid interaction technique; some recent methods are described and examples are given of their use, both in two and three dimensions, including comparisons with experiment. (B) inverse methods in which the shape is calculated explicitly, as a result of either (a) specifying the surface pressure distribution on the wing, or (b) requiring that some suitable ‘target’ function, usually the drag/lift ratio, shall be a minimum. At present, these methods are restricted to inviscid flow. Several examples of both ‘pressure’ and ‘optimisation’ methods are discussed, and their advantages and limitations considered.","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":"94 1","pages":"1 - 16"},"PeriodicalIF":1.4,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1017/S0001924000022326","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57253092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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