Pub Date : 1999-05-01DOI: 10.1017/S0001924000027937
G. Dimitriadis, J. Cooper
The prediction and characterisation of the limit cycle oscillation (LCO) behaviour of non-linear aeroelastic systems has become of great interest recently. However, much of this work has concentrated on determining the existence of LCOs. We concentrate on LCO stability. By considering the energy present in different limit cycles, and also using the harmonic balance method, it is shown how the stability of limit cycles can be determined. The analysis is then extended to show that limit cycles can be controlled, or even suppressed, by the use of suitable excitation signals. A basic control scheme is developed to achieve this, and is demonstrated on a simple simulated non-linear aeroelastic system
{"title":"Limit Cycle Oscillation Control and Suppression","authors":"G. Dimitriadis, J. Cooper","doi":"10.1017/S0001924000027937","DOIUrl":"https://doi.org/10.1017/S0001924000027937","url":null,"abstract":"The prediction and characterisation of the limit cycle oscillation (LCO) behaviour of non-linear aeroelastic systems has become of great interest recently. However, much of this work has concentrated on determining the existence of LCOs. We concentrate on LCO stability. By considering the energy present in different limit cycles, and also using the harmonic balance method, it is shown how the stability of limit cycles can be determined. The analysis is then extended to show that limit cycles can be controlled, or even suppressed, by the use of suitable excitation signals. A basic control scheme is developed to achieve this, and is demonstrated on a simple simulated non-linear aeroelastic system","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"1999-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1017/S0001924000027937","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57253140","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 : 1999-04-01DOI: 10.1017/S000192400009655X
Norton Lord Kings
In 1943, with the world still at war, a great discussion on the future of aeronautical education was held by the Royal Aeronautical Society. Not only would the war years, however many were still to come, demand more well-qualified aeronautical engineers, but the longed for peace years, with engineers turning swords into ploughshares, would want more. The discussion was in two parts. One took place on 25 June and the other on 23 July. Many of the leading figures in British aeronautics took part and in the chair on both occasions was Dr Roxbee Cox, a vice-president of the society. The discussion culminated in a resolution based on a proposal by Marcus Langley. That resolution and the discussion which led to it resulted in the recommendation by the Aeronautical Research Committee that a post-graduate college of aeronautical science should be established. This was followed by governmental action. Sir Stafford Cripps, then the minister responsible for aircraft production, set up a committee presided over by Sir Roy Fedden to make specific proposals, and the committee recommended in its 1944 report that such a college should be a new and independent establishment. In 1945 the government created the College of Aeronautics board of governors under the chairmanship of Air Chief Marshal Sir Edgar Ludlow-Hewitt to bring the college into existence and govern it. The first meeting of this board took place on 28 June 1945 and there were present: Sir Edgar Ludlow Hewitt, Dr W. Abbot, Mr Hugh Burroughs, Sir Roy Fedden, Mr J. Ferguson, Sir Harold Hartley, Sir William Hil-dred, Sir Melvill Jones, Dr E.B. Moullin, Mr J.D. North, Sir Frederick Handley Page, Mr E.F. Relf, Dr H. Roxbee Cox, Air Marshal Sir Ralph Sovley, Rear Admiral S.H. Troubridge and Mr W.E.P. Ward. Sir William Stanier, who had been appointed, was not present.
{"title":"Extract from A Wrack Behind","authors":"Norton Lord Kings","doi":"10.1017/S000192400009655X","DOIUrl":"https://doi.org/10.1017/S000192400009655X","url":null,"abstract":"In 1943, with the world still at war, a great discussion on the future of aeronautical education was held by the Royal Aeronautical Society. Not only would the war years, however many were still to come, demand more well-qualified aeronautical engineers, but the longed for peace years, with engineers turning swords into ploughshares, would want more. The discussion was in two parts. One took place on 25 June and the other on 23 July. Many of the leading figures in British aeronautics took part and in the chair on both occasions was Dr Roxbee Cox, a vice-president of the society. The discussion culminated in a resolution based on a proposal by Marcus Langley. That resolution and the discussion which led to it resulted in the recommendation by the Aeronautical Research Committee that a post-graduate college of aeronautical science should be established. This was followed by governmental action. Sir Stafford Cripps, then the minister responsible for aircraft production, set up a committee presided over by Sir Roy Fedden to make specific proposals, and the committee recommended in its 1944 report that such a college should be a new and independent establishment. In 1945 the government created the College of Aeronautics board of governors under the chairmanship of Air Chief Marshal Sir Edgar Ludlow-Hewitt to bring the college into existence and govern it. The first meeting of this board took place on 28 June 1945 and there were present: Sir Edgar Ludlow Hewitt, Dr W. Abbot, Mr Hugh Burroughs, Sir Roy Fedden, Mr J. Ferguson, Sir Harold Hartley, Sir William Hil-dred, Sir Melvill Jones, Dr E.B. Moullin, Mr J.D. North, Sir Frederick Handley Page, Mr E.F. Relf, Dr H. Roxbee Cox, Air Marshal Sir Ralph Sovley, Rear Admiral S.H. Troubridge and Mr W.E.P. Ward. Sir William Stanier, who had been appointed, was not present.","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"1999-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1017/S000192400009655X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57256029","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 : 1999-03-01DOI: 10.1017/S0001924000065003
D.W. Joynson
{"title":"Advances in Missile Guidance Theory , J. Z. Ben-Asher and I. Yaesh, American Institute of Aeronautics and Astronautics, 1801 Alexander Bell Drive, Reston, VA 20191–4344, USA. 1998. 188pp. $64.95 (AIAA members), $79.95 (Non-members).","authors":"D.W. Joynson","doi":"10.1017/S0001924000065003","DOIUrl":"https://doi.org/10.1017/S0001924000065003","url":null,"abstract":"","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"1999-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83104119","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 : 1998-07-01DOI: 10.1017/S0001924000016171
B. Nageswara Rao, G. Venkateswara Rao
Abstract Combined effects of geometrical and material non-linearities on a cantilever beam having symmetrical cross-section about its central axis with a rotational distributed loading are studied. It is assumed that the stress-strain relation in compression is identical to that in tension. Due to this, the neutral axis coincides with the central axis of the beam. The problem is formulated by means of an integral equation which is suitably converted to a system of nonlinear ordinary differential equations which are solved using a simple and accurate numerical method. Details of the load deflection characteristics for an I-beam and for a beam of rectangular cross-section are presented.
{"title":"Large deflection analysis of cantilever beams of symmetrical cross-section subjected to a rotational distributed loading including the effect of material nonlinearity","authors":"B. Nageswara Rao, G. Venkateswara Rao","doi":"10.1017/S0001924000016171","DOIUrl":"https://doi.org/10.1017/S0001924000016171","url":null,"abstract":"Abstract Combined effects of geometrical and material non-linearities on a cantilever beam having symmetrical cross-section about its central axis with a rotational distributed loading are studied. It is assumed that the stress-strain relation in compression is identical to that in tension. Due to this, the neutral axis coincides with the central axis of the beam. The problem is formulated by means of an integral equation which is suitably converted to a system of nonlinear ordinary differential equations which are solved using a simple and accurate numerical method. Details of the load deflection characteristics for an I-beam and for a beam of rectangular cross-section are presented.","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"1998-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1017/S0001924000016171","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57253027","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 : 1997-10-01DOI: 10.1017/S0001924000066070
B. V. van Oudheusden
Abstract A critical revision is made of the classic power-law expressions that describe the effect of the Prandtl number on laminar heat transfer and temperature recovery for Pr near one, by applying a perturbation analysis to the energy equation for constant-property flow. In this way, the Pr dependence is obtained as a systematic asymptotic expansion up to any desired order, which provides a more accurate and convenient procedure than classic curve-fitting methods. The effect of pressure gradient and flow sweep are examined for self-similar yawed wedge flows.
{"title":"A note on the Prandtl number effect on laminar heat transfer and recovery","authors":"B. V. van Oudheusden","doi":"10.1017/S0001924000066070","DOIUrl":"https://doi.org/10.1017/S0001924000066070","url":null,"abstract":"Abstract A critical revision is made of the classic power-law expressions that describe the effect of the Prandtl number on laminar heat transfer and temperature recovery for Pr near one, by applying a perturbation analysis to the energy equation for constant-property flow. In this way, the Pr dependence is obtained as a systematic asymptotic expansion up to any desired order, which provides a more accurate and convenient procedure than classic curve-fitting methods. The effect of pressure gradient and flow sweep are examined for self-similar yawed wedge flows.","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"1997-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57255274","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 : 1997-10-01DOI: 10.1017/S0001924000066045
A. Giunta, V. Balabanov, D. Haim, B. Grossman, W. Mason, L. T. Watson, R. Haftka
Abstract The presence of numerical noise in engineering design optimisation problems inhibits the use of many gradient-based optimisation methods. This numerical noise may result in the inaccurate calculation of gradients which in turn slows or prevents convergence during optimisation, or it may promote convergence to spurious local optima. The problems created by numerical noise are particularly acute in aircraft design applications where a single aerodynamic or structural analysis of a realistic aircraft configuration may require tens of CPU hours on a supercomputer. The computational expense of the analyses coupled with the convergence difficulties created by numerical noise are significant obstacles to performing aircraft multidisciplinary design optimisation. To address these issues, a procedure has been developed to create noise-free algebraic models of subsonic and supersonic aerodynamic performance quantities, for use in the optimisation of high-speed civil transport (HSCT) aircraft configurations. This procedure employs methods from statistical design of experiments theory and response surface modelling to create the noise-free algebraic models. Results from a sample HSCT design problem involving ten variables are presented to demonstrate the utility of this method.
{"title":"Multidisciplinary optimisation of a supersonic transport using design of experiments theory and response surface modelling","authors":"A. Giunta, V. Balabanov, D. Haim, B. Grossman, W. Mason, L. T. Watson, R. Haftka","doi":"10.1017/S0001924000066045","DOIUrl":"https://doi.org/10.1017/S0001924000066045","url":null,"abstract":"Abstract The presence of numerical noise in engineering design optimisation problems inhibits the use of many gradient-based optimisation methods. This numerical noise may result in the inaccurate calculation of gradients which in turn slows or prevents convergence during optimisation, or it may promote convergence to spurious local optima. The problems created by numerical noise are particularly acute in aircraft design applications where a single aerodynamic or structural analysis of a realistic aircraft configuration may require tens of CPU hours on a supercomputer. The computational expense of the analyses coupled with the convergence difficulties created by numerical noise are significant obstacles to performing aircraft multidisciplinary design optimisation. To address these issues, a procedure has been developed to create noise-free algebraic models of subsonic and supersonic aerodynamic performance quantities, for use in the optimisation of high-speed civil transport (HSCT) aircraft configurations. This procedure employs methods from statistical design of experiments theory and response surface modelling to create the noise-free algebraic models. Results from a sample HSCT design problem involving ten variables are presented to demonstrate the utility of this method.","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"1997-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1017/S0001924000066045","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57255193","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 : 1997-05-01DOI: 10.1017/S0001924000066380
D R Buttsworth, T V Jones
Convective heat transfer data is frequently obtained from transient surface temperature measurements. Thin film resistance gauges, thermocouples, and thermochromic liquid crystals, are used in various situations to measure the surface temperature history. By assuming that uniform semi-infinite flat plate conditions apply, it is possible to express the instantaneous surface heat flux as an analytical function of the transient surface temperature(1). Various approaches can be used to account for the presence of multi-layered substrates and finite thickness substrate effects (Schultz and Jones(1); Doorly and Oldfield(2); Guo et al (3)), however, the effects of surface curvature are usually neglected.
对流换热数据通常是从瞬态表面温度测量中获得的。薄膜电阻计，热电偶和热致变色液晶，在各种情况下用于测量表面温度历史。假设存在均匀半无限平板条件，则可以将瞬态表面热通量表示为瞬态表面温度的解析函数(1)。可以使用各种方法来解释多层基底和有限厚度基底效应的存在(Schultz和Jones(1);Doorly and Oldfield(2);Guo等(3))，然而，表面曲率的影响通常被忽略。
{"title":"Radial conduction effects in transient heat transfer experiments","authors":"D R Buttsworth, T V Jones","doi":"10.1017/S0001924000066380","DOIUrl":"https://doi.org/10.1017/S0001924000066380","url":null,"abstract":"Convective heat transfer data is frequently obtained from transient surface temperature measurements. Thin film resistance gauges, thermocouples, and thermochromic liquid crystals, are used in various situations to measure the surface temperature history. By assuming that uniform semi-infinite flat plate conditions apply, it is possible to express the instantaneous surface heat flux as an analytical function of the transient surface temperature(1). Various approaches can be used to account for the presence of multi-layered substrates and finite thickness substrate effects (Schultz and Jones(1); Doorly and Oldfield(2); Guo et al (3)), however, the effects of surface curvature are usually neglected.","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"1997-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1017/S0001924000066380","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57255301","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 : 1997-02-01DOI: 10.1017/S0001924000066768
G. Losilevskii
Abstract Energy considerations are used to find the spanwise circulatory lift distribution yielding minimal induced resistance for a harmonically oscillating planar wing in a steady incompressible flow. Under the restriction that the time-averaged and oscillatory constituents of the wing's circulatory lift are known, the optimal distribution is such that its time-averaged constituent is elliptical, but the oscillatory one is generally not. The latter varies from elliptical to rectangular as the frequency of the oscillations increases. When the oscillatory part of the lift is not prescribed, present results infer that its reduction — as, for example, by an elastic twist — will typically reduce the drag, even if the twist yields a non-optimal (for that lift) lift distribution.
{"title":"A problem of minimal induced resistance in unsteady motion","authors":"G. Losilevskii","doi":"10.1017/S0001924000066768","DOIUrl":"https://doi.org/10.1017/S0001924000066768","url":null,"abstract":"Abstract Energy considerations are used to find the spanwise circulatory lift distribution yielding minimal induced resistance for a harmonically oscillating planar wing in a steady incompressible flow. Under the restriction that the time-averaged and oscillatory constituents of the wing's circulatory lift are known, the optimal distribution is such that its time-averaged constituent is elliptical, but the oscillatory one is generally not. The latter varies from elliptical to rectangular as the frequency of the oscillations increases. When the oscillatory part of the lift is not prescribed, present results infer that its reduction — as, for example, by an elastic twist — will typically reduce the drag, even if the twist yields a non-optimal (for that lift) lift distribution.","PeriodicalId":50846,"journal":{"name":"Aeronautical Journal","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"1997-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57255345","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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