Numerical analysis of subsonic turbulent jets
Başlık çevirisi mevcut değil.
- Tez No: 523294
- Danışmanlar: Dr. WOLFGANG SCHRÖDER, Dr. PETER JESCHKE
- Tez Türü: Doktora
- Konular: Makine Mühendisliği, Mechanical Engineering
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 2017
- Dil: İngilizce
- Üniversite: Rheinisch-Westfälische Technische Hochschule Aachen
- Enstitü: Yurtdışı Enstitü
- Ana Bilim Dalı: Belirtilmemiş.
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: 129
Özet
Özet yok.
Özet (Çeviri)
Noise reduction is one of the major tasks in todays aircraft development and it is also one of the key goals in the European ACARE 2050 targets, which require the perceived noise level of flying aircraft to be reduced by 65 %. The jet development in the near field is strongly influenced by the larger scales of turbulent motions which are in turn affected by the nozzle geometry and the main wing. The prediction of jet noise sources needs detailed knowledge about the unsteady flow field, which can be obtained via highly resolved large eddy simulations (LES). In line with this perspective, this thesis analyzes the impact of nozzle interior details and nozzle exit conditions on the flow and the resulting sound field, and the flow field of a complete nozzle-wing geometry including slat, airfoil, and flap to investigate the sensitivity of flow conditions on the nozzle-wing interaction in the jet near field. First, LES of turbulent axisymmetric hot jets are conducted. Three nozzle geometries of increasing complexity, i.e., a clean nozzle without any built-in components, a centerbody nozzle, and a nozzle with centerbody plus 5 struts are considered to investigate the influence of nozzle interior details on the overall flow and acoustic field. The results evidence that the flow field in the region 35 nozzle radii downstream of the exit is dominated by the flow structures induced by the geometry. Additional nozzle built-in components enhance the turbulent mixing by increasing the turbulent intensity in the jet near field. The centerbody perturbed nozzle configurations reveal a spectral peak in the near nozzle exit region which is caused by the wake flow from the centerbody. Moreover, the centerbody nozzle increases the overall sound pressure level (OASPL) in the near field compared to the clean nozzle and the centerbody-plus-strut nozzle reduces it compared to the centerbody nozzle due to the increased turbulent mixing. It is found that the spectral peak appeared in the flow field analysis also occurs in the acoustic near field. Thereafter, the flow and the acoustic field of two jets are analyzed to determine the impact of exit conditions on the jet development. First, the flow inside the nozzle is part of the overall nozzle-jet analysis such that the turbulent flow at the nozzle exit is determined by the solution of the full discrete conservation equations. This configuration corresponds to the centerbody nozzle solution. Second, the nozzle exit distributions which are used as inflow distributions for the free jet analysis are based on the mean flow profiles plus vortex rings. That is, for the latter case the impact of the nozzle geometry on the jet is not directly taken into account, the nozzle exit distribution is imposed. The flow field analysis shows that the flow field immediately downstream of the nozzle exit is strongly influenced by the flow structures induced by the nozzle geometry. The nozzle included solution possesses an almost 30% higher peak turbulence intensity level which also results in a massively enhanced velocity decay. The peak observed in the centerbody nozzle configuration can not be seen in the nozzle modeled solution since the vortices which generate the peak shedding from centerbody are missing. It is, moreover, found that both jet configurations reveal quite a different qualitative behavior of the sound spectra, especially in the sideline direction where the entropy source term dominates the sound generation. This difference occurs since the noise sources generated by the artificial perturbations are not perfectly mimicked in the nozzle modeled solution. However, the total overall sound pressure level shows the same qualitative behavior for both nozzle configurations. Towards the downstream direction, the sound spectra of both solutions converge. Finally, apart from the conventional isolated nozzle-jet analysis in which there is no flow-solid-body interaction in the free jet field, 3D unsteady flow simulations of a realistic ultra-high bypass-ratio engine and wing are considered to define the influence of various engine conditions on the jet development when there is jet-wing interaction in the free jet region. The Mach number of the wind tunnel is M=0.176, the jet Mach number is M=0.352. Two fan flow conditions are considered where the Mach number of the first setup is M=0.376, and M=0.43 for the second setup. The Reynolds number based on the wind tunnel velocity is Re=150,000. It is found that increasing the fan jet velocity increases the core length of the jet and the turbulence intensity level. Furthermore, spectral analysis in the near jet region suggests that the characteristic frequency of the shear layer instabilities considerably decreases near the wing geometry due to the jet-wing interaction compared to the distributions in the lower side of the jet stream where there is no flow-solid-body interface.
Benzer Tezler
- İçten yivli dairesel jet akışın deneysel ve sayısal akışkanlar dinamiği (SAD) ile incelenmesi
Analysis of jet flow in a grooved circular conduit by experimental and computational fluid dynamics (CFD) method
TUGAY ŞİŞMAN
Yüksek Lisans
Türkçe
2013
Makine MühendisliğiMarmara ÜniversitesiMakine Eğitimi Ana Bilim Dalı
YRD. DOÇ. DR. AHMET TALAT İNAN
PROF. DR. MEHMET ZAFER GÜL
- Eksenel bir fanın sayısal gürültü modelinin oluşturulması ve fan kapağı boşluk geometrisinin ses yayılımına etkisinin deneysel olarak incelenmesi
Numerical noise modelling of axial fan and experimental investigation of effect of fan cover gap geometry on sound radiation
İSMAİL KONUR
Yüksek Lisans
Türkçe
2020
Makine Mühendisliğiİstanbul Teknik ÜniversitesiMakine Mühendisliği Ana Bilim Dalı
PROF. DR. VAHİT MERMERTAŞ
- Analysis of stability and transition in flat plate compressible boundary layers using linear stability theory
Düz levhalar üzerindeki sıkıştırılabilir sınır tabakalarda doğrusal kararlılık teorisi ile kararlılık ve geçiş analizi
HAYRİYE SENEM ATALAYER
Yüksek Lisans
İngilizce
2004
Havacılık MühendisliğiOrta Doğu Teknik ÜniversitesiHavacılık ve Uzay Mühendisliği Ana Bilim Dalı
DOÇ.DR. SERKAN ÖZGEN
- Numerical analysis of air flow around various airfoil types
Çeşitli uçak kanadı tiplerinin etrafındaki hava akışının numerik analizi
KÜBRA NUR YORGANCI
Yüksek Lisans
İngilizce
2022
Makine MühendisliğiAnkara Yıldırım Beyazıt ÜniversitesiMakine Mühendisliği Ana Bilim Dalı
DR. ÖĞR. ÜYESİ KEMAL BİLEN
- Computational analysis of external store carriage in transonic speed regime
Harici yük taşımanın transonik sürat bölgesinde hesaplamalı analizi
İ. CENKER ASLAN
Yüksek Lisans
İngilizce
2003
Havacılık Mühendisliğiİstanbul Teknik ÜniversitesiUçak Mühendisliği Ana Bilim Dalı
DOÇ. DR. AYDIN MISIRLIOĞLU
PROF. DR. OKTAY BAYSAL