Finite-time arbitrary-motion unsteady cascade airfoil theory for helicopter rotors in hoverA complete and detailed derivation of finite-time arbitrary-motion cascade theory is presented for both Laplace and frequency domains. This theory includes the effect of returning wakes for both single- and multibladed rotors. The generalized cascade lift-deficiency function (CLDF) is shown to be consistent with the generalized Theodorsen lift-deficiency function when the wake spacing approaches infinity or when the reduced frequency tends to infinity. This function predicts correct zero-reduced-frequency limit. Accurate and efficient numerical procedures are presented for the evaluation of the CLDF. Numerical examples comparing the CLDF with Loewy's lift deficiency function in frequency domain are presented. Accurate Pade approximants of the CLDF are constructed using a Bode-plot approach which allows for complex poles.
Document ID
19870061650
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Dinyavari, M. A. H. (California Univ. Los Angeles, CA, United States)
Friedmann, P. P. (California, University Los Angeles, United States)