Investigations of boundary-layer transition and airloads on rotating blades

Publikation: Qualifikations-/Studienabschlussarbeit › Dissertation

Autoren

  • Armin Weiss

Organisationseinheiten

Forschungs-netzwerk anzeigen

Details

OriginalspracheEnglisch
QualifikationDoktor der Ingenieurwissenschaften
Gradverleihende Hochschule
Betreut von
  • Markus Raffel, Betreuer*in
Datum der Verleihung des Grades20 Aug. 2018
ErscheinungsortHannover
PublikationsstatusVeröffentlicht - 2018

Abstract

Die experimentelle Erfassung des Oberflächendrucks, sowie des laminar-turbulenten Grenzschichtumschlags auf Rotorblättern ist wichtig um numerische Verfahren validieren zu können, die z.B. die Rotoreffizienz im Entwurfsprozess vorhersagen. In dieser Arbeit wurden Oberflächendrücke und Grenzschichttransition auf einem Mach-skalierten Helikopterrotorblatt gemessen. Hierfür wurden örtlich hochauflösende optische Messverfahren eingesetzt und durch integrale Schub- sowie diskrete Druckmessungen ergänzt. Die bei unterschiedlichen kollektiven Steuerwinkeln untersuchten und auf die Blattspitzengeschwindigkeit sowie Sehnenlänge bezogenen Reynolds- und Machzahlen ergeben sich zu Re_tip = 4.6 - 9.3 x 10^5 und M_tip = 0.29 - 0.57. Es wird ein optimiertes pressure-sensitive paint (PSP) Messsystem vorgestellt, welches Messartefakte verhindert, die durch Bildunschärfe infolge Rotation entstehen. Das System wurde erstmalig und erfolgreich an der untersuchten Konfiguration angewendet. Grenzschichttransitionslagen wurden mittels temperature-sensitive paint (TSP) und vergleichsweise mittels Infrarotthermographie detektiert. Ausgewählte Daten stehen nun für Validierungszwecke von numerischen Methoden zur Verfügung. Erstmalig wurde der Einfluss von rotierenden Kräften auf Grenzschichttransition am Rotorblatt systematisch untersucht. Ein Effekt von Rotationskräften bei Variation der Rossbyzahl von Ro = 6.95 auf Ro = 4.76 und bei resultierenden Reynolds- und Machzahlen von Re_res = 3.74 x 10^5 und M_res = 0.22 konnte ist insignifikant. Druckmessdaten bei 77 % des Blattradius wurden mit Berechnungen eines gekoppelten zweidimensionalen Euler-/ Grenzschichtlösers verglichen. Die numerischen Lösungen wurden weiterverwendet, um kritische N-faktoren auf Basis zweier unterschiedlicher eN-Methoden und ausschließlich unter Annahme einer zweidimensionalen Strömung zu bestimmen. Die Vergleichbarkeit zwischen gemessenen und gerechneten Oberflächendrücken liegt innerhalb von Delta c_p ≈ 0.02 und die Vorhersagbarkeit der gemessenen Grenzschichttransitionslagen bei Verwendung der ermittelten N-Faktoren ist besser als ± 5 % der Sehnenlänge.

Zitieren

Investigations of boundary-layer transition and airloads on rotating blades. / Weiss, Armin.
Hannover, 2018. 121 S.

Publikation: Qualifikations-/Studienabschlussarbeit › Dissertation

Weiss, A 2018, 'Investigations of boundary-layer transition and airloads on rotating blades', Doktor der Ingenieurwissenschaften, Gottfried Wilhelm Leibniz Universität Hannover, Hannover. https://doi.org/10.15488/3865
Weiss, A. (2018). Investigations of boundary-layer transition and airloads on rotating blades. [Dissertation, Gottfried Wilhelm Leibniz Universität Hannover]. https://doi.org/10.15488/3865
Weiss A. Investigations of boundary-layer transition and airloads on rotating blades. Hannover, 2018. 121 S. doi: 10.15488/3865
Download
@phdthesis{5264072bda2a438badece9d027ade1aa,
title = "Investigations of boundary-layer transition and airloads on rotating blades",
abstract = "Measurements of surface pressure and boundary-layer transition on rotating blades is important for the validation of numerical tools, used e.g. to predict rotor efficiency in the design process. In this work, surface pressure distributions and boundary-layer transition were measured on a Mach-scaled helicopter rotor blade. Optical measurement techniques were used to obtain data at high spatial resolution and were complemented by integral thrust and local surface pressure tap measurements. Various collective pitch settings were investigated at tip chord Reynolds and Mach numbers of Re_{tip} = 4.6 - 9.3 x 10^5 and M_{tip} = 0.29 - 0.57. An optimized pressure-sensitive paint (PSP) system is presented, which allows omitting error-prone post-processing routines or laborious setups to eliminate artifacts originating from rotational image blur. The system was successfully applied for the first time to the investigated configuration. Boundary-layer transition positions were detected via temperature-sensitive paint (TSP) and for comparison also via infrared thermography. A data base was established, which is ready to use for validation purposes of numerical codes. For the first time, the effect of rotational forces on boundary-layer transition was systematically investigated. A rotational effect is found to be insignificant as the scaling parameter in terms of Rossby number Ro is varied from Ro = 6.95 to Ro = 4.76 at resulting Reynolds and Mach numbers of Re_{res} = 3.74 x 10^5 and M_{res} = 0.22. Measured surface pressure data at 77 % tip radius were compared to numerical solutions of a coupled two-dimensional Euler/ boundary-layer solver and the numerical solutions were used to determine critical N-factors based on two different approaches to the e^N-method, each based on two-dimensional flow assumptions only. Measured and calculated surface pressures are comparable within a difference of Delta c_p ≈ 0.02. Application of the determined N-factors yields a prediction capability of measured boundary-layer transition results of better than ± 5 % of the chord.",
author = "Armin Weiss",
note = "Doctoral thesis",
year = "2018",
doi = "10.15488/3865",
language = "English",
school = "Leibniz University Hannover",

}

Download

TY - BOOK

T1 - Investigations of boundary-layer transition and airloads on rotating blades

AU - Weiss, Armin

N1 - Doctoral thesis

PY - 2018

Y1 - 2018

N2 - Measurements of surface pressure and boundary-layer transition on rotating blades is important for the validation of numerical tools, used e.g. to predict rotor efficiency in the design process. In this work, surface pressure distributions and boundary-layer transition were measured on a Mach-scaled helicopter rotor blade. Optical measurement techniques were used to obtain data at high spatial resolution and were complemented by integral thrust and local surface pressure tap measurements. Various collective pitch settings were investigated at tip chord Reynolds and Mach numbers of Re_{tip} = 4.6 - 9.3 x 10^5 and M_{tip} = 0.29 - 0.57. An optimized pressure-sensitive paint (PSP) system is presented, which allows omitting error-prone post-processing routines or laborious setups to eliminate artifacts originating from rotational image blur. The system was successfully applied for the first time to the investigated configuration. Boundary-layer transition positions were detected via temperature-sensitive paint (TSP) and for comparison also via infrared thermography. A data base was established, which is ready to use for validation purposes of numerical codes. For the first time, the effect of rotational forces on boundary-layer transition was systematically investigated. A rotational effect is found to be insignificant as the scaling parameter in terms of Rossby number Ro is varied from Ro = 6.95 to Ro = 4.76 at resulting Reynolds and Mach numbers of Re_{res} = 3.74 x 10^5 and M_{res} = 0.22. Measured surface pressure data at 77 % tip radius were compared to numerical solutions of a coupled two-dimensional Euler/ boundary-layer solver and the numerical solutions were used to determine critical N-factors based on two different approaches to the e^N-method, each based on two-dimensional flow assumptions only. Measured and calculated surface pressures are comparable within a difference of Delta c_p ≈ 0.02. Application of the determined N-factors yields a prediction capability of measured boundary-layer transition results of better than ± 5 % of the chord.

AB - Measurements of surface pressure and boundary-layer transition on rotating blades is important for the validation of numerical tools, used e.g. to predict rotor efficiency in the design process. In this work, surface pressure distributions and boundary-layer transition were measured on a Mach-scaled helicopter rotor blade. Optical measurement techniques were used to obtain data at high spatial resolution and were complemented by integral thrust and local surface pressure tap measurements. Various collective pitch settings were investigated at tip chord Reynolds and Mach numbers of Re_{tip} = 4.6 - 9.3 x 10^5 and M_{tip} = 0.29 - 0.57. An optimized pressure-sensitive paint (PSP) system is presented, which allows omitting error-prone post-processing routines or laborious setups to eliminate artifacts originating from rotational image blur. The system was successfully applied for the first time to the investigated configuration. Boundary-layer transition positions were detected via temperature-sensitive paint (TSP) and for comparison also via infrared thermography. A data base was established, which is ready to use for validation purposes of numerical codes. For the first time, the effect of rotational forces on boundary-layer transition was systematically investigated. A rotational effect is found to be insignificant as the scaling parameter in terms of Rossby number Ro is varied from Ro = 6.95 to Ro = 4.76 at resulting Reynolds and Mach numbers of Re_{res} = 3.74 x 10^5 and M_{res} = 0.22. Measured surface pressure data at 77 % tip radius were compared to numerical solutions of a coupled two-dimensional Euler/ boundary-layer solver and the numerical solutions were used to determine critical N-factors based on two different approaches to the e^N-method, each based on two-dimensional flow assumptions only. Measured and calculated surface pressures are comparable within a difference of Delta c_p ≈ 0.02. Application of the determined N-factors yields a prediction capability of measured boundary-layer transition results of better than ± 5 % of the chord.

U2 - 10.15488/3865

DO - 10.15488/3865

M3 - Doctoral thesis

CY - Hannover

ER -