Abstract
The paper presents CFD results for the transonic flow of dry and moist air through a diffuser and a compressor rotor. In both test geometries, i.e. the Sajben transonic diffuser and the NASA Rotor 37, the air humidity impact on the structure of flows with weak shock waves was examined. The CFD simulations were performed by means of an in-house CFD code, which was the RANS-based modelling approach to compressible flow solutions. It is shown that at high values of relative humidity, above 70%, the modelling of the transonic flow field with weak shock waves by means of the dry air model may produce wrong results.
Highlights
Atmospheric air always contains a certain amount of water or steam
The subject of this paper is to present the influence of air humidity on the performance of the transonic diffuser and the compressor rotor in the presence of weak shock waves
DYKAS Sławomir et al Influence of Air Humidity on Transonic Flows with Weak Shock Waves weakens the shock wave, shifting it downstream, and increases the static temperature in the supersonic region compared to the calculations for dry air (Fig. 4)
Summary
Atmospheric air always contains a certain amount of water or steam. The water content in atmospheric air is usually represented using relative humidity, which is the ratio between the amount of water contained in the air and the amount the air can hold. Elevated relative humidity values affect the characteristic of the wing under the transonic flow conditions [2,3,4,5]. They may have a significant influence on the flow in the turbine engine elements [6]. The moist air transonic flow in the turbine engine can take place in the compressor (or fan) inlet channels or in the compressor (or fan) rotor blade-to-blade channels In both cases, the transition from subsonic to supersonic conditions (and vice versa) is carried out on weak shock waves. As already shown in previous works [7], for relative humidity lower than 70%, CFD results obtained for moist and dry air do not differ significantly in terms of changes in the flow structure
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