A safe design process and its application are introduced to a concept study for circular variable aero engine inlets. The paper highlights the tasks of inlets, the compromise in designing them and how using variable inlets could solve this compromise and allow for faster and more efficient commercial aircraft. However, high safety and reliability requirements bring up disadvantages. Tackling these disadvantages, a systems engineering approach is complemented by a safety assessment process, according to Aerospace Recommended Practice ARP 4754A. Safety methods that are applicable during early phases of the product development process are presented and applied to develop feasible variable inlet concepts. Hence, safety requirements, potential failure events and resulting failure modes are systematically identified, assessed and mitigated. The mitigation of a failure condition by the means of redundancy within the adjustment control system is presented.
This paper presents the challenge of ice protection within a concept study for variable aero engine inlets in civil aviation. An overview of variable inlet concept groups, ice detection and protection mechanisms is given. These ice protection systems are assigned to the respective inlet concept groups and evaluated regarding economic, functional and safety requirements to determine the most suitable combinations.
Social and leadership skills are often neglected
during studies (especially in STEM subjects). It is precisely these
skills that are urgently needed in professional life. The CoMeT
“Concepts, Methods and Techniques for Project Management”
module was developed to meet the need to acquire social and
leadership skills. After a preliminary consideration an overview
of the module is given. First, the teaching and learning concept is
presented and insights into the seminar work are given. In
addition to the competence-oriented examination methods, the
integration of digital elements are presented. The continuous
further development of the module, adapted to the needs of
students and the economy, is a constant goal of the teachers. For
this reason, there are already transmission possibilities of the
module in planning. Instead of instructing groups of students in
project work, pupils are to be introduced to science and study
through small projects.
This paper presents the application of a scientific project concerning variable aero engine inlets, which was conducted within the scope of a high school course over the period of two years. The motivation of developing variable aero engine inlets with a group of pupils is introduced. The approach that is utilised during that course and its implementation are described. The results and benefits of this project for pupils, supervisor, school and university are summarised, e.g. providing the pupils with necessary knowledge and assisting them with their career choices, potentially resulting in increased enrolment numbers and lower dropout rates in science, technology, engineering and mathematics study programmes. An overview of a follow-up project that enables a larger group of pupils and a yearly implementation of a similar course is given. Within the scope of that course, university students will supervise smaller scientific projects that are conducted by groups of pupils over the period of one semester, providing additional benefits for students’ soft skills, e.g. communication and conflict management skills.
This paper presents design adaptations during the further development of innovative broadband acoustic liner concepts (Foil Helmholtz Resonator Liner; FHR-Liners) which utilise flexible foils within a honeycomb structure to attenuate engine and aircraft noise. The requirements for acoustic liners in aviation are described and utilised to derive evaluation criteria. Modifications of the FHR-Liner concept are introduced. A suitable concept evaluation method based on VDI 2225 is applied to evaluate the modified liner concepts concerning the main evaluation criteria.
This paper presents the challenge of ice protection within a concept study for variable pitot inlets of aero engines in transonic and supersonic civil aviation. An overview of variable inlet concept groups that adjust the inlet geometry by rigid segment repositioning, elastic surface deformation, or boundary layer control is given. Ice detection mechanisms and various pneumatic, fluid, as well as electric ice protection systems are presented. These ice protection systems are assigned to the respective inlet concept groups and evaluated regarding economic, functional, and safety requirements by means of pairwise comparison and weighted point rating to determine the most suitable combinations.
This paper reveals the influence of selected geometric parameters on the aerodynamic performance of circular variable aero engine inlets in transonic and supersonic civil aviation. The trade-off in inlet design and aerodynamic evaluation parameters are presented. The approach to investigate the dependencies between the aerodynamic and geometric parameters at different flight conditions by means of a parametric design study is introduced. The dependencies of inlet drag and efficiency from geometric parameters at flight speeds of Mach 0.95 up to Mach 1.6 are identified. Although entailing additional weight, the inlet length represents the parameter with the highest potential for drag reduction by up to 50% in the selected design space. Ideal geometries for variable pitot inlets are determined. After considering weight, their potential range benefit nearly disappears for subsonic applications, but remains above 20% for supersonic flight at Mach 1.6.
This paper describes the selection of the ideal variable inlet concept group by utilising results of aerodynamic investigations, system safety analyses and integration studies. Aerodynamic and functional inlet requirements are explained and variable inlet concept groups are introduced. The concept evaluation by means of a weighted point rating is presented. The respective concept groups are analysed and evaluated regarding economic, functional and safety requirements. By means of this evaluation, the concept group that adjusts the inlet geometry by rigid segment repositioning is identified as most suitable concept group. The early selection of the most suitable concept group enables more detailed subsequent concept investigations, potentially enabling the technology of variable inlets for future commercial aircraft.
The motivation for designing variable pitot inlets for future supersonic transport (SST) is explained. A comprehensive overview of existing technological solutions for variable leading edges of aircraft wings and engines inlets is given. The advantages and limitations of over 80 solutions, as well as their relevance for application on variable pitot inlets for SST are analysed. These analyses emphasis challenges of existing solution options concerning design methodologies, level of detail and experience with a technology.
Interest High School Students in STEM Studies, while Preparing STEM Students for Leading Positions
(2021)
This paper presents an approach to product rating and evaluation of different product solutions for broadband attenuation acoustic liner concepts for aerospace application. In the process, corresponding requirements have been defined for the considered system and evaluation criteria have been derived. Three “Main Evaluation Categories” (Acoustics, System Safety and Integration, Structure and Material) have been introduced to not falsify the assessment results by subject-specific exclusion criteria. A ranked space method has been selected for weighting the evaluation criteria to ensure an objective and knowledge-based rating. The rating has been carried out by a weighted point rating. Concise operational requirements and previously not considered system functions have been identified and linked to the rating and evaluation process. Building on this, further steps for the optimisation and development of the acoustic liner concepts have been presented and explained.
Common cause analysis of circular variable nacelle inlet concepts for aero engines in civil aviation
(2018)
This paper presents the application of a safe design process within a concept study for variable aero engine inlets. The safety assessment method Common Cause Analysis (CCA), consisting of a Zonal Safety Analysis (ZSA), a Particular Risk Analysis (PRA) and a Common Mode Analysis (CMA), is performed on variable inlet concepts. By the means of the CCA individual failure modes and external events, which can lead to failure conditions, are identified. Potential design adaptations to mitigate these failure conditions are presented.
A systems engineering approach to develop variable nacelle intakes for aero engines in civil aviation is presented. The goal of this methodical approach is to find solutions to design problems that can be successfully utilised in aviation without further effort during the certification. By using variable intakes, aircraft and aero engine manufacturers can fulfil their customers’ needs for safe, efficient and fast travelling. Therefore, a system shall be installed which is able to modify the nacelle intake contour between two extrema. On the one hand, a sharp thin contour, which produces low drag and allows to fly faster or more efficiently, is optimal during cruise condition. On the other hand, a round thick intake lip is necessary to avoid flow separations with the potential to cause dangerous events during take-off and climb conditions.
The utilised systems engineering approach is introduced. The executed steps and methods used for creating and evaluating concept variants for variable intakes are displayed particularly. Those contain the determination and evaluation of requirements and functions, as well as the generation and assessment of concepts. Finally yet importantly, following tasks are presented.
Purpose – This paper aims to reveal the influence of selected geometric parameters on the aerodynamic performance of circular variable aero engine inlets in transonic and supersonic civil aviation. Design/methodology/approach – The trade-off in inlet design and aerodynamic evaluation parameters is presented. The approach to investigate the dependencies between the aerodynamic and geometric parameters at different flight conditions by means of a parametric design study is introduced. Findings – The dependencies of inlet drag and efficiency from geometric parameters at flight speeds of Mach 0.95 up to Mach 1.6 are identified. Although entailing additional weight, the inlet length represents the parameter with the highest potential for drag reduction by up to 50% in the selected design space. Ideal geometries for variable pitot inlets are determined. After considering weight, their potential range benefit nearly disappears for subsonic applications, but remains above 20% for supersonic flight at Mach 1.6.
Originality/value – Hence, the technology of circular variable pitot inlets for supersonic transport aircraft could be a way to achieve the ambitious ecological, safety and economic goals for future civil aviation.
Purpose – This paper aims to describe the selection of the ideal variable inlet concept group by using results of aerodynamic investigations, system safety analyses and integration studies.
Design/methodology/approach – Aerodynamic and functional inlet requirements are explained and variable inlet concept groups are introduced. The concept evaluation by means of a weighted point rating is presented. The respective concept groups are analysed and evaluated regarding economic, functional and safety requirements.
Findings – By means of this evaluation, the concept group that adjusts the inlet geometry by rigid segment repositioning is identified as most suitable concept group.
Originality/value – The early selection of the most suitable concept group enables more detailed subsequent concept investigations, potentially enabling the technology of variable inlets for future commercial aircraft.
An overview of aero-engine inlets, the design process in aviation and a safe design approach for academic studies is provided. By means of a safe design approach, a variable inlet concept is developed up to technology readiness level (TRL) 3 and described. The application of safety and reliability methods, aerodynamic and structural analyses, as well as functional demonstrators proves the feasibility of the present variable inlet concept and highlights its potential for application in future supersonic transport (SST).
A systems engineering approach to develop variable nacelle intakes for aero engines in civil aviation is presented. The goal of this methodical approach is to find solutions to design problems that can be successfully utilised in aviation without further effort during the certification. By using variable intakes, aircraft and aero engine manufacturers can fulfil their customers’ needs for safe, efficient and fast travelling. Therefore, a system shall be installed which is able to modify the nacelle intake contour between two extrema. On the one hand, a sharp thin contour, which produces low drag and allows to fly faster or more efficiently, is optimal during cruise condition. On the other hand, a round thick intake lip is necessary to avoid flow separations with the potential to cause dangerous events during take-off and climb conditions. The utilised systems engineering approach is introduced. The executed steps and methods used for creating and evaluating concept variants for variable intakes are displayed particularly. Those contain the determination and evaluation of requirements and functions as well as the generation and assessment of concepts. Finally, yet importantly, following tasks are presented.
Selected methods of the aviation safety assessment process according to ARP 4761 are introduced and conducted within the scope of a concept study for future broadband acoustic liners. While having similar primary functions and basic design, the acoustic liner concepts diverge concerning subfunctions and potential malfunctions. With the ARP 4761 safety assessment methods, significant differences in sub functions and possible malfunctions of the concepts can be identified. The results of the safety assessment are discussed, and the concepts are evaluated in terms of feasibility and safety.
The challenge of determining ideal inlet geometries for variable pitot aero engine inlets in transonic and supersonic civil aviation is presented. The trade-off in inlet design and the geometric inlet parameters are introduced. By means of a parametric design study, feasible inlet geometries for variable inlets are identified and the potential aerodynamic benefit of using variable pitot inlets for flight speeds from Mach 0.95, 1.3 up to 1.6 is examined. After considering the additional weight of variable inlets, for instance due to required actuators, a remaining range benefit of over 20% at a flight speed of Mach 1.6 is determined.
This paper focusses on the challenge of determining the ideal inlet geometries within a concept study for variable pitot aero engine inlets in transonic and supersonic civil aviation. The trade-off in inlet design and the geometric parameters of inlets for different Mach numbers are introduced. The utilised process of the parametric design study and its implementation are presented. The dependencies of inlet drag and occurrence of flow separation from geometric parameters are examined. The ideal inlet geometries are identified to determine the potential aerodynamic benefit of using variable pitot inlets. The comparison of the identified geometries with the reference reveals a significant drag reduction at the investigated flight speeds of Mach 0.95, 1.3 and 1.6. While the drag reduction potentially leads to decreased fuel consumption and increased flight range, the application of variable inlet systems entails additional weight and complexity. By means of a simplified Breguet range equation, the benefit of using variable pitot inlets has been determined. For an additional weight of 500 kg per variable inlet, the range benefit nearly disappears for subsonic applications up to Mach 0.95, while a range benefit of over 20% remains for supersonic applications at Mach 1.6.
The motivation for designing variable pitot inlets for future supersonic transport (SST) is explained. A comprehensive overview of existing technological solutions for variable leading edges of aircraft wings and engine inlets is given. The advantages and limitations of over 80 solutions, as well as their relevance for application on variable pitot inlets for SST are described. The challenges of existing solution options concerning design methodologies, level of detail, and experience with a technology are identified.