東華大學圖書館 |

語系: 繁體中文

說明(常見問題)

回圖書館首頁

手機版館藏查詢

登入

回首頁

切換: 標籤 | MARC模式 | ISBD

The Aerodynamics of a Modern Warship.

Mateer, Rebecca.

FindBook

Google Book

Amazon

博客來

The Aerodynamics of a Modern Warship.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	The Aerodynamics of a Modern Warship./
作者:	Mateer, Rebecca.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2020,
面頁冊數:	236 p.
附註:	Source: Dissertations Abstracts International, Volume: 82-04, Section: B.
Contained By:	Dissertations Abstracts International82-04B.
標題:	Naval engineering. -
電子資源:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28179428
ISBN:	9798672105925

The Aerodynamics of a Modern Warship.
Mateer, Rebecca.

The Aerodynamics of a Modern Warship. - Ann Arbor : ProQuest Dissertations & Theses, 2020 - 236 p.

Source: Dissertations Abstracts International, Volume: 82-04, Section: B.

Thesis (Ph.D.)--The University of Liverpool (United Kingdom), 2020.

This item must not be sold to any third party vendors.

Although modern warships routinely operate with on-board helicopters, the effect of the ship superstructure aerodynamics on the flying environment around the ship is generally not considered in the design process. The modern warship is now well designed for stealth in warfare, but the now bulkier, smooth-sided and sharp-edged superstructures create a significant disturbance to the oncoming wind, resulting in turbulent flow features in the lee of the ship, most often across the stern where the ship's flight deck is located. Such conditions, coupled with hot exhaust gases from the ship's gas turbine engines, everchanging weather resulting in various sea-states, sea-spray, rain, fog, etc. create a potentially very hazardous operational environment. In addition, as the launch of unmanned aircraft (UA) vehicles from the flight deck is becoming commonplace, their successful launch and recovery is also directly impacted by the scale of the turbulent flow features in the vicinity of the flight deck.Through the use of time-accurate Computational Fluid Dynamics (CFD), this thesis addresses the impact of modern warship aerodynamics on helicopter and UAV operations. Full-scale, time-accurate, unsteady airwakes have been produced for an early design of the UK Royal Navy's new Global Combat Ship (GCS), the Type 26 City-Class, and its predecessor, the Type 23 Duke-Class. The larger, stealthier design of the GCS has been shown to produce a more aggressive airwake compared with its predecessor, resulting in higher turbulence levels across the flight deck and greater aerodynamic loading on a helicopter. The larger main mast of the GCS also has a clear effect on the accuracy of the ship's anemometer readings when compared with Type 23 thereby making it difficult to determine if the wind conditions are safe for helicopter launch and recovery. Simulation of the Type 23 and GCS exhaust gas efflux has shown that the more turbulent airwake of the GCS aids the cooling and dispersion of the ship's exhaust gases with air temperatures above the flight deck being comparatively lower for the GCS in headwind and Green 30 wind-over-deck (WOD) conditions. As such, the dispersing engine exhaust plume of Type 23 presents a greater threat to the helicopter.Detailed analysis of the air flow around the GCS main mast has shown how CFD can be used to predict flow distortion at the ship's anemometers. Issues with current practice for positioning anemometers on bulky main mast structures, detailed in the defence standard, DEFSTAN 00-133 Part 2, have been highlighted. Findings show that the defence standard should be modified to take account of the new ship geometries that are emerging; at the least, anemometers should be placed as high up the mast structure as possible on yard arms of suitable length. Additionally, an appropriately placed aft anemometer is recommended to yield more accurate wind measurements from astern.Analysis of the exhaust gas dispersion from the GCS has shown that significant cooling of the plume is achieved through the hot exhaust gases mixing with the ship's turbulent airwake, but elevated, unsteady temperatures are present in the vicinity of the flight deck, particularly in the port side hover position in a Green 30 WOD, that can adversely affect an operating helicopter. The addition of an eductor to the exhaust outlet does reduce temperatures above the flight deck, but the temperatures remain elevated and unsteady.A new method for simulating the launch of lightweight unmanned aircraft into the turbulent CFD-generated ship airwake has been also developed. The simulation environment has shown potential for developing Unmanned Aircraft (UA) for maritime applications, for developing appropriate flight controllers, and for developing appropriate launch and recovery operational procedures.

ISBN: 9798672105925Subjects--Topical Terms:

3173824
Naval engineering.
Subjects--Index Terms:

Computational Fluid Dynamics

The Aerodynamics of a Modern Warship.
LDR:04949nmm a2200337 4500 001 2280301
005 20210830065537.5
008 220723s2020 ||||||||||||||||| ||eng d
020 $a 9798672105925
035 $a (MiAaPQ)AAI28179428
035 $a (MiAaPQ)Liverpool_3089205
035 $a AAI28179428
040 $a MiAaPQ $c MiAaPQ
100 1 $a Mateer, Rebecca. $3 3558812
245 1 4 $a The Aerodynamics of a Modern Warship.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2020
300 $a 236 p.
500 $a Source: Dissertations Abstracts International, Volume: 82-04, Section: B.
500 $a Advisor: White, Mark;Owen, Ieuan.
502 $a Thesis (Ph.D.)--The University of Liverpool (United Kingdom), 2020.
506 $a This item must not be sold to any third party vendors.
520 $a Although modern warships routinely operate with on-board helicopters, the effect of the ship superstructure aerodynamics on the flying environment around the ship is generally not considered in the design process. The modern warship is now well designed for stealth in warfare, but the now bulkier, smooth-sided and sharp-edged superstructures create a significant disturbance to the oncoming wind, resulting in turbulent flow features in the lee of the ship, most often across the stern where the ship's flight deck is located. Such conditions, coupled with hot exhaust gases from the ship's gas turbine engines, everchanging weather resulting in various sea-states, sea-spray, rain, fog, etc. create a potentially very hazardous operational environment. In addition, as the launch of unmanned aircraft (UA) vehicles from the flight deck is becoming commonplace, their successful launch and recovery is also directly impacted by the scale of the turbulent flow features in the vicinity of the flight deck.Through the use of time-accurate Computational Fluid Dynamics (CFD), this thesis addresses the impact of modern warship aerodynamics on helicopter and UAV operations. Full-scale, time-accurate, unsteady airwakes have been produced for an early design of the UK Royal Navy's new Global Combat Ship (GCS), the Type 26 City-Class, and its predecessor, the Type 23 Duke-Class. The larger, stealthier design of the GCS has been shown to produce a more aggressive airwake compared with its predecessor, resulting in higher turbulence levels across the flight deck and greater aerodynamic loading on a helicopter. The larger main mast of the GCS also has a clear effect on the accuracy of the ship's anemometer readings when compared with Type 23 thereby making it difficult to determine if the wind conditions are safe for helicopter launch and recovery. Simulation of the Type 23 and GCS exhaust gas efflux has shown that the more turbulent airwake of the GCS aids the cooling and dispersion of the ship's exhaust gases with air temperatures above the flight deck being comparatively lower for the GCS in headwind and Green 30 wind-over-deck (WOD) conditions. As such, the dispersing engine exhaust plume of Type 23 presents a greater threat to the helicopter.Detailed analysis of the air flow around the GCS main mast has shown how CFD can be used to predict flow distortion at the ship's anemometers. Issues with current practice for positioning anemometers on bulky main mast structures, detailed in the defence standard, DEFSTAN 00-133 Part 2, have been highlighted. Findings show that the defence standard should be modified to take account of the new ship geometries that are emerging; at the least, anemometers should be placed as high up the mast structure as possible on yard arms of suitable length. Additionally, an appropriately placed aft anemometer is recommended to yield more accurate wind measurements from astern.Analysis of the exhaust gas dispersion from the GCS has shown that significant cooling of the plume is achieved through the hot exhaust gases mixing with the ship's turbulent airwake, but elevated, unsteady temperatures are present in the vicinity of the flight deck, particularly in the port side hover position in a Green 30 WOD, that can adversely affect an operating helicopter. The addition of an eductor to the exhaust outlet does reduce temperatures above the flight deck, but the temperatures remain elevated and unsteady.A new method for simulating the launch of lightweight unmanned aircraft into the turbulent CFD-generated ship airwake has been also developed. The simulation environment has shown potential for developing Unmanned Aircraft (UA) for maritime applications, for developing appropriate flight controllers, and for developing appropriate launch and recovery operational procedures.
590 $a School code: 0722.
650 4 $a Naval engineering. $3 3173824
653 $a Computational Fluid Dynamics
653 $a Modern warships
653 $a Superstructure aerodynamics
690 $a 0468
710 2 $a The University of Liverpool (United Kingdom). $3 1684840
773 0 $t Dissertations Abstracts International $g 82-04B.
790 $a 0722
791 $a Ph.D.
792 $a 2020
793 $a English
856 4 0 $u https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28179428