Identification of efficient geometries for variable pitot inlets for supersonic transport

Abstract

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.

Review of variable leading-edge patents for aircraft wings and engine inlets and their relevance for variable pitot inlets in future supersonic transport

“…On the other hand, a geometry with reduced drag can be implemented during cruise flight conditions. This drag reduction results in potential range benefits of up to 5% for solely subsonic applications and up to 30% for supersonic applications with flight speeds up to Mach 1.6 [16,17].…”

“…-the curvature of the inlet lip, -the cross-sectional areas at inlet entry and throat level, -the lengths of inlet lip, diffuser, and nacelle forebody, as well as -the curvature of the nacelle forebody [16], compare Fig. 2.…”

“…Hence, within the scope of a feasibility study for variable inlet concepts, the methodological design process according to VDI 2221 [27] has been supplemented with the safety assessment process in aviation according to Aerospace Recommended Practices ARP 4754A [25]. The resulting development process comprises -the review of relevant existing solution options for variable pitot inlets, compare chapter 3, -the identification of ideal inlet geometries concerning drag and flow uniformity for different flight speeds up to Mach 1.6 and the potentially resulting aerodynamic benefit [6,16], -the development of concept groups that adjust the inlet geometry by adjustment of rigid segments, by deformation of elastic surface materials, or by boundary layer control [5,28], -the application of the safety methods Functional Hazard Assessment (FHA), Fault Tree Analysis (FTA), and Common Cause Analysis (CCA) [29,30], -integration studies concerning ice protection systems [31], as well as -the manufacturing of functional prototypes to demonstrate the feasibility of the developed concepts [32,33].…”

Aeroacoustic and Aerodynamic Adjoint-Based Shape Optimization of an Axisymmetric Aero-Engine Intake

“…For a similar application, in [30], the continuous adjoint to a hybrid RANS/FW-H analogy noise prediction tool was used, which resulted in noise reduction only in a certain direction, without an extra aerodynamic performance criterion. Regarding the design of intake geometries, the interested reader may refer to [31][32][33][34]. In [31], a method for optimizing subsonic inlet design, involving iterative geometry refinement based on critical operating conditions, is outlined.…”

“…In [31], a method for optimizing subsonic inlet design, involving iterative geometry refinement based on critical operating conditions, is outlined. The authors in [32] investigate the impact of selected geometric parameters on axisymmetric aero-engine inlets' performance in transonic/supersonic civil aviation, suggesting that optimizing inlet length has substantial drag reduction potential at supersonic conditions. In [33], a multi-objective optimization is presented for compact engine intakes at Mach 0.9, using axisymmetric RANS simulations.…”