Print Email Facebook Twitter Sensitivity of Pusher Propeller Performance and Noise Emissions to the UpstreamWake Characteristics: An Experimental and Numerical Study Title Sensitivity of Pusher Propeller Performance and Noise Emissions to the UpstreamWake Characteristics: An Experimental and Numerical Study Author Channa, V.V. Contributor Sinnige, T. (mentor) Veldhuis, L.L.M. (mentor) Faculty Aerospace Engineering Department Flight propulsion and performance Programme Flight propulsion and performance Date 2015-10-30 Abstract Open rotors are considered to have the potential to improve the fuel economy of aircraft significantly by improving the propulsive efficiency compared to the current generation turbofan engines. One of the possible configurations for the open rotors is the aft fuselage mounted contra-rotating pusher propeller. The aftfuselage mounted contra-rotating pusher propeller offers significant benefits in terms of interior noise and ground clearance compared to the wing mounted propeller aircraft. However, the pusher configuration is subjected to a non-uniform inflow due to the upstream pylon wake which affects the aerodynamic performance and noise emissions of the propeller. The objective of this research is to analyse the sensitivity of the pusher propeller performance and noise emissions to the upstream pylon wake characteristics by both experiments and numerical computations. The experiments are conducted at Delft University of Technology. To validate the experiments, a numerical model was developed using an existing propeller lifting line code coupled with an analytical model to estimate the effect of pylon wake on pusher propeller performance and noise emissions. The pylon wake velocity measurements in the freestream direction are affected by the presence of the downstream propeller. With a decrease in advance ratio, the negative pressure gradient upstream of the propeller decreases the non-dimensional wake displacement thickness and the non-dimensional wake velocity deficit. The wake profiles measured at zero thrust condition and computed numerically are in good agreement, with differences in velocity deficit of the order of 2%. The propeller performance results indicated that the rotating shaft balance used could not measure the pylon installation effect accurately. The measured offset in propeller performance is attributed to an error in measurement. Within the limitation of the accuracy of RSB, the propeller performance measurements for different pylon-propeller spacings remained constant. Numerical computations are also performed to evaluate the effect of the pylon wake on the propeller performance. The effect of installation increases with increase in advance ratio. The experimental noise measurements indicated an increase in sound pressure levels with the installation of pylon. The effect of installation is seen as tones at blade passage frequency. The Flyover directivity pattern indicated an increase in sound pressure level at all flyover angles measured. The increase in sound pressure level due to the installation of pylon is prominent both upstream and downstream of the propeller due to the low sound pressure level observed for the isolated configuration. Numerical evaluations showed that the computed sound pressure levels are underpredicted for the isolated configuration at low freestream velocities which is due to the decrease in radiation efficiency at low freestream velocity. The sound pressure level for the pylon-installed configuration computed showed an increase across all the flyover angles. From the experimental and numerical investigations performed, the effect of installation on the propeller performance is negligible whereas the effect on the propeller noise emissions is significant. This result is of significance as it can be used as an advantage in the design of the pusher propeller. Subject propellerperformanceacoustics To reference this document use: http://resolver.tudelft.nl/uuid:e32f84f1-21da-4a5a-a541-2f15b041ede5 Part of collection Student theses Document type master thesis Rights (c) 2015 Channa, V.V. Files PDF Channa_Msc_Thesis.pdf 13.99 MB Close viewer /islandora/object/uuid:e32f84f1-21da-4a5a-a541-2f15b041ede5/datastream/OBJ/view