Basic Principles – Gas Turbine Compatibility – Intake Aerodynamic Aspects

Abstract

Engine/intake compatibility covers the mutual dependencies between the aircraft intake and the gas turbine. Flow physical effects in both the intake and/or the gas turbine can reduce stability margins of the propulsion system dramatically, possibly resulting in unstable performance or engine flameout. Besides exhibiting optimal performance it is of utmost importance that stable propulsion operation in the whole flight envelope of a jet aircraft is ensured. In this chapter, the sources of possible intake flow distortions will be described. The state of the art for the quantification of intake flow distortion by the use of distortion parameters is presented together with possible methods for measuring the data for the calculation of these parameters. Existing experience and current research efforts with the aim of reducing flow distortion in intakes are highlighted.

Jet Engine Inlet Distortion Screen and Descriptor Evaluation

“…[2,10]. It has been used extensively in the European fighter programs Tornado and Eurofighter [8]. It is also built into the calculations of compressor performance in the GasTurb program [11].…”

“…Some references [8] define the reference dynamic pressure at the AIP instead of the inlet. This difference effects the resultant calculation, because the dynamic pressure value at the AIP is influenced by the pressure distortion and thus gives similar but slightly smaller DC60 values.…”

“…As a result, quantitative measures, commonly known as distortion descriptors or distortion parameters, are used to describe the distortion. Many descriptors were developed by different engine manufacturers in the 60 s and 70 s. There have been some efforts to catalogue and compare different descriptors throughout the years [6][7][8]. The descriptors differ in complexity.…”

Passive Flow Control Study in an S-Duct Using Stereo Particle Image Velocimetry

“…The investigation comprised a variation in the numbers of VG and lateral spacing (ls) with a VG height in the same order or magnitude as the local boundary layer thickness (h/δ in =1. 35). An overall improvement in pressure based distortion descriptors at the AIP was achieved with a reduction of up to about 50% in Anderson and Gibb [21] investigated the effect of rectangular VGs to reduce the distortion at the AIP on an Sduct geometry (A out /A in = 1.4, H/L =0.3).…”

“…sector 〈 0 ̅̅̅ 60° 〉 non-dimentionalized by the mean dynamic head q of the AIP [35]. The dynamic head is calculated from the time-averaged wall static pressure measured with a circumferential resolution of 5° at the AIP.…”