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Publikationen von Professorinnen und Professoren der HAW Hamburg

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Referenzen

2018

Zeitschriftenbeiträge:

pdf
Dieter Scholz
Definition and Discussion of the Intrinsic Efficiency of Winglets
INCAS BULLETIN, 10(1):117-134
2018
ISSN: 2066–8201

Schlüsselwörter: wingtip, winglet, induced drag, wing mass, aircraft design

Marker: TI-FF

Zusammenfassung: Three simple equations are derived to define the "Intrinsic Aerodynamic Efficiency of Winglets" independent of the horizontal extension of the winglet and independent of the winglet’s (relative) height. This Intrinsic Aerodynamic Efficiency allows a quick comparison of purely the aerodynamic shape of winglets independent of the selected size chosen for a certain aircraft installation. The Intrinsic Aerodynamic Efficiency is calculated in 3 steps: STEP 1: The relative total drag reduction due to the winglet is converted into an assumed contribution of the winglet only on the span efficiency factor. STEP 2: If the winglet also increases span, its performance is converted into one without the effect of span increase. STEP 3: The winglet’s reduction in induced drag is compared to a horizontal wing extension. If the winglet needs e.g. to be three times longer than the horizontal extension to achieve the same induced drag reduction, its Intrinsic Aerodynamic Efficiency is the inverse or 1/3. Winglet metrics as defined are calculated from literature inputs. In order to evaluate winglets further, the mass increase due to winglets is estimated in addition to the reduction of drag on aircraft level and fuel burn.

Konferenz-/Workshop-/Podiumsdiskussionsbeiträge, Ausstellungs-/Modenschaubeteiligungen:

pdf
Dieter Scholz
Cabin Air Contamination - An Aeronautical Perspective (59. Kongress der Deutschen Gesellschaft für Pneumologie und Beatmungsmedizin e.V., Dresden, 16. März 2018)
2018

Marker: TI-FF

Zusammenfassung: Purpose: This presentation gives an introduction to aircraft cabin air contamination with an emphasis on contamination due to jet engine oil entering the cabin from the jet engine or auxiliary power unit (APU) via the bleed air system and the air conditioning system. The possible application of sensors and filters is discussed. Filters can be retrofitted. A bleed-free air conditioning architecture, however, seems only financially viable for newly designed aircraft. --- Design/methodology/approach: The presentation collects existing facts and combines them with own thoughts. --- Findings: There is a real health and flight safety risk due to contaminated cabin air. For the infrequent flyer the risk is very low. Also aviation statistics are not dominated by cabin air related accidents. Nevertheless, a bleed air based air conditioning system can be regarded as applying a fundamentally wrong systems engineering approach. Measures have to be taken to solve this. --- Research limitations/implications: This review study is based on references. Own measurements have not been made. --- Practical implications: The topic has been presented as background information for respiratory physicians. --- Originality/value: Engineering based information with a critical view on the topic seems to be missing in public. This presentation tries to fill this gap.

default
Dieter Scholz
End-of-Life for Cabin Equipment - Disposal or Recycling (Panel Discussion, Forecast Sessions, Aircraft Interiors Expo, Hamburg, 11.04.2018)
Verlag: Flight Global,
2018

Marker: TI-FF

2017

Zeitschriftenbeiträge:

pdf
Mike Gerdes, Diego Galar und Dieter Scholz
Genetic Algorithms and Decision Trees for Condition Monitoring and Prognosis of A320 Aircraft Air Conditioning
Insight - Non-Destructive Testing and Condition Monitoring, 59(8):424 - 433
August 2017
ISSN: 1354-2575

Marker: TI-FF

Zusammenfassung: Unscheduled maintenance is a large cost driver for airlines, but condition monitoring and prognosis can reduce the number of unscheduled maintenance actions. The paper shows condition monitoring can be introduced into most system by adopting a data-driven approach and using existing data sources. The goal is to forecast the remaining useful life (RUL) of a system based on various sensor inputs. We use decision trees to learn the characteristics of a system. The data for the decision tree training and classification are processed by a generic parametric signal analysis. To obtain the best classification results for the decision tree, the parameters are optimized by a genetic algorithm. A forest of three different decision trees with different signal analysis parameters is used as classifier. The proposed method is validated with data from an A320 aircraft from ETIHAD Airways. Validation shows condition monitoring can classify the sample data into ten predetermined categories, representing the total useful life (TUL) in 10 percent steps. This is used to predict the RUL. There are 350 false classifications out of 850 samples. Noise reduction reduces the outliers to nearly zero, making it possible to correctly predict condition. It is also possible to use the classification output to detect a maintenance action in the validation data.

pdf
Ellen Pflaum und Dieter Scholz
Aircraft Design (Flugzeugentwurf)
Synergie - Fachmagazin für Digitalisierung in der Lehre, Sonderband: HOOU Content Projekte 2015/16:238-241
2017
ISSN: 2509-3088

Schlüsselwörter: Flugzeug; Entwurf; Flugzeugentwurf; Auslegung; Sizing; Aircraft; Design

Marker: TI-FF

Zusammenfassung: Ausgehend von den Anforderungen werden Schritt für Schritt die Parameter des Flugzeuges ermittelt, z. B. Schub, Flügelfläche, Nutzlast, benötigte Kraftstoffmasse, Leermasse, Start- und Landemasse und später dann Kabine, Rumpf, Flügel und Leitwerke.

pdf
Mike Gerdes, Diego Galar und Dieter Scholz
Decision Trees and the Effects of Feature Extraction Parameters for Robust Sensor Network Design
Eksploatacja i Niezawodnosc – Maintenance and Reliability, 19(1):31-42
2017
ISSN: 1507-2711

Schlüsselwörter: decision trees, feature extraction, sensor optimization, sensor fusion, sensor selection

Marker: TI-FF

Zusammenfassung: Reliable sensors and information are required for reliable condition monitoring. Complex systems are commonly monitored by many sensors for health assessment and operation purposes. When one of the sensors fails, the current state of the system cannot be calculated in same reliable way or the information about the current state will not be complete. Condition monitoring can still be used with an incomplete state, but the results may not represent the true condition of the system. This is especially true if the failed sensor monitors an important system parameter. There are two possibilities to handle sensor failure. One is to make the monitoring more complex by enabling it to work better with incomplete data; the other is to introduce hard or software redundancy. Sensor reliability is a critical part of a system. Not all sensors can be made redundant because of space, cost or environmental constraints. Sensors delivering significant information about the system state need to be redundant, but an error of less important sensors is acceptable. This paper shows how to calculate the significance of the information that a sensor gives about a system by using signal processing and decision trees. It also shows how signal processing parameters influence the classification rate of a decision tree and, thus, the information. Decision trees are used to calculate and order the features based on the information gain of each feature. During the method validation, they are used for failure classification to show the influence of different features on the classification performance. The paper concludes by analysing the results of experiments showing how the method can classify different errors with a 75% probability and how different feature extraction options influence the information gain.

Konferenz, Symposium, Vortragsreihe, Einzelausstellung, Modenschau, Künstl. Leitung (als Ausrichter):

pdf
Dieter Scholz
Aircraft Cabin Air and Engine Oil - A Systems Engineering View (Hamburg Aerospace Lecture Series: DGLR, RAeS, VDI, ZAL, HAW Hamburg together with VC and UFO HAW Hamburg, 27 April 2017)
Zenodo.org

Schlüsselwörter: aircraft, cabin, cabin air, contamination, quality, health, safety

Marker: TI-FF

Zusammenfassung: Purpose: This presentation gives an introduction to aircraft cabin air quality and contamination risks. Beyond these fundamentals, most of the current engineering issues discussed with respect to the topic are explained. --- Design/methodology/approach: The literature review is complemented with own explanations, thoughts and derivations. --- Findings: There is a real health and flight safety risk due to contaminated cabin air. For the infrequent flyer the risk is very low. Also aviation statistics are not dominated by cabin air related accidents. Nevertheless, a bleed air based air conditioning system can be regarded as applying a fundamentally wrong systems engineering approach. Measures have to be taken. --- Research limitations/implications: This review study is based on references. Own measurements have not been made. --- Practical implications: Passengers and crew are made aware of the risk of cabin air contamination based on technical facts. Steps towards a solution of the problem are presented as they can be applied by passengers, pilots, airlines and manufacturers respectively. --- Social implications: Better knowledge of the problem should enable passengers and crew to maintain a firm position in the sometimes heated discussion. --- Originality/value: Engineering based information with a critical view on the topic seems to be missing in public. This presentation tries to fill this gap.

pdf
Dieter Scholz
Aircraft Cabin Air and Engine Oil - An Engineering View
International Aircraft Cabin Air Conference 2017
Imperial College London
19. - 20. September 2017
Conference Presentations
Global Cabin Air Quality Executive (GCAQE)

Schlüsselwörter: cabin air, aircraft, passenger, engine, oil, air conditioning, bleed air

Marker: TI-FF

Zusammenfassung: Air conditioning in aviation means temperature control, pressure control and ventilation. The cabin is vented with a certain percentage (e.g. 50%) of fresh outside air. The remaining part of the air for cabin ventilation is provided as air from the cabin, filtered and recirculated back into the cabin. At cruise altitude, ambient pressure is below cabin pressure. Hence, the outside air needs to be compressed before it is delivered into the cabin. The air is compressed in the engine compressor and tapped off as "bleed air" at temperatures reaching 400 °C or more. Hence, bleed air cooling is necessary. The engine shaft is supported by lubricated bearings. They are sealed against the air in the compressor usually with labyrinth seals. It is explained why jet engine seals leak oil by design in small quantities. The amount of oil leakage can be estimated with a new equation. The estimate shows the same order of magnitude as measured in flight (Cranfield study, EASA study). The oil leaking into the compressor contains problematic additives which get pyrolized (burned) at the elevated temperatures in the compressor, leaving more than 100 substances behind, some of them hazardous and some known as Volatile Organic Compounds (VOC). An alternative source for the compressed air is the Auxiliary Power Unit (APU). Like the aircraft's jet engine, it is a gas turbine, built much in the same way when it comes to bearings and seals. For this reason, also compressed air from the APU is potentially contaminated. Engineering standards from SAE contain guidance about sound engineering design principles for air conditioning systems of airplanes. Also certification standards give some guidance, however, more general. In essence, bleed air systems as we see them on today's passenger jet aircraft should not be built the way they are. For immediate action, hints are given: In case of smoke in the cockpit pilots should read the carbon monoxide (CO) concentration from a personal CO detector as an objective indicator in addition to their human senses. The present CO concentration should be compared with values obtained under normal conditions. If pilots are alerted and it is suitable (fuel reserves, terrain clearance), pilots should consider to descend to 10000 ft, reduce speed and ventilate the aircraft by means of the ram air inlet. This is the only source of fresh air in flight, independent of engines or APU. If smoke is present, checklists tell pilots to put on their oxygen mask. Cabin crew should consider wearing a personal breathing mask in such cases. Technically the easiest way to install carbon filters to filter VOCs in existing aircraft is in the recirculation path, where HEPA filters are already in use. Unfortunately the physics are such that filters in the recirculation path cannot remove substances fully. It is only possible to reduce the concentration down to a value depending on filtration rate and recirculation rate. With typical values the incoming VOC concentration can be reduced to about 60%. In case of full filtration (including ducts from the bleed air sources) incoming VOC concentration can be reduced to about 18%. Aircraft from the beginning of the jet age (B707, DC-8) used turbocompressors keeping bleed air and outside air compressed for cabin ventilation separate. Based on past experience, turbocompressors cannot be considered a solution for future aircraft. A final solution to the problem of contaminated cabin air is seen in electric (bleed free) cabin air supply architectures. Here, outside air for cabin ventilation is compressed separately in dedicated clean compressors. Bleed free cabin air architectures have the additional advantage of much improved fuel economy. So far, the Boeing 787 is the only passenger aircraft in service with a bleed free cabin air architecture. Airbus could follow with related technology already available and checked in test flights.

pdf
Dieter Scholz
An Ecolabel for Aircraft
Deutscher Luft- und Raumfahrtkongress 2017
München
05. - 07. September 2017
Online Publikationen zum DLRK 2017 (Deutscher Luft- und Raumfahrtkongress, 05. - 07. September 2017, München, Deutschland)
Deutsche Gesellschaft für Luft- und Raumfahrt (DGLR)

Schlüsselwörter: LCA, Ecolabel, aircraft, environment, fuel, consumption, global warming, CO2, air, airport, noice

Marker: TI-FF

Zusammenfassung: In attempting to increase the environmental awareness in the aviation sector and to eliminate the green washing phenomenon, an investigation was done into the development and definition of an ecolabel for aircraft. Based on life cycle assessment it was found that aviation affects the environment most with the impact categories resource depletion and global warming (both due to fuel consumption), local air pollution (due to the nitrogen oxide emissions in the vicinity of airports) and noise pollution. For each impact category a calculation method was developed based solely on official, certified and publicly available data to meet the stated requirements of the ISO standards about environmental labeling. To ensure that every parameter is evaluated independent on aircraft size, which allows comparison between different aircraft, normalizing factors such as number of seats, rated thrust and noise level limits are used. Additionally, a travel class weighting factor is derived in order to account for the space occupied per seat in first class, business class and economy class. To finalize the ecolabel, the overall environmental impact is determined by weighting the contribution of each impact category. For each category a rating scale from A to G is developed to compare the performance of the aircraft with that of others. The harmonization of the scientific and environmental information, presented in an easy understandable label, enables the traveling customers to make a well informed and educated choice when booking a flight, selecting among airline offers with different types of aircraft and seating arrangements.

pdf
Dieter Scholz
Definition and Discussion of the Intrinsic Efficiency of Winglets
6th CEAS Air & Space Conference
Bucharest, Romania
16. - 20. October 2017
Aerospace Europe - CEAS 2017
Council of European Aerospace Societies

Schlüsselwörter: wingtip, winglet, induced drag, wing mass, aircraft design

Marker: TI-FF

Zusammenfassung: Three simple equations are derived to define the "intrinsic aerodynamic efficiency of winglets" independent of the horizontal extension of the winglet and independent of the winglet’s (relative) height. This "intrinsic aerodynamic efficiency" allows a quick comparison of purely the aerodynamic shape of winglets independent of the selected size chosen for a certain aircraft installation. The intrinsic aerodynamic efficiency is calculated in 3 steps: STEP 1: The relative total drag reduction due to the winglet is converted into an assumed contribution of the winglet only on the span efficiency factor. STEP 2: If the winglet also increases span, its performance is converted into one without the effect of span increase. STEP 3: The winglet’s reduction in induced drag is compared to a horizontal wing extension. If the winglet needs e.g. to be three times longer than the horizontal extension to achieve the same induced drag reduction, its "intrinsic aerodynamic efficiency" is the inverse or 1/3. Winglet metrics as defined are calculated from literature inputs. In order to evaluate winglets further, the mass increase due to winglets is estimated in addition to the reduction of drag on aircraft level and fuel burn.

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Letzte Änderung: 23.01.15

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