Asitav Mishra
Asitav Mishra is an Assistant Research Scientist in the Department of Aerospace Engineering at the University of Maryland as well as at the NIA since Oct 2017. His earlier research experiences include post-doctoral scholar positions at the University of Michigan (2015-2017) and the University of Wyoming (2012-2015) following his Ph.D in Aerospace Engineering from the University of Maryland in 2012. His research interests include adjoint based coupled multi-disciplinary fixed and rotary-wing design optimization, vortex wake-lifting surface interactions as well as performance predictions in rotary wing flows, and high performance computing using heterogenous GPU/CPU computing paradigms applied to CFD problems.
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problems is presented in this paper. The hybrid aeroacoustic approach, in which a near
body CFD solver is coupled to an FW-H acoustic module that propagates the rotor noise
signature to a far field observer, has been followed in this work. Both forward and adjoint
sensitivity formulations are derived that correspond to analogues of the aeroacoustic
analysis problem. The fully coupled aeroacoustic analysis formulation is first verified to
effectively perform noise predictions of a four bladed HART2 rotor in trimmed forward flight.
Upon successful verification, the adjoint formulation is used to minimize helicopter rotor
noise signatures via blade shape optimization.
which is particularly advantageous for aerodynamic design optimization, where hundreds of flow solutions
are required. However, generating body-fitted multiblock meshes for complex geometries is
challenging and is a time consuming task. The overset mesh technique greatly reduces the manual effort
required to generate meshes over complex geometries by overlapping a series of simpler meshes.
However, generating the necessary connectivity information between meshes in a robust and computationally
efficient manner remains a challenge. We address this challenge by developing an efficient
parallel overset grid assembly technique based on implicit hole cutting that is fully automatic. The
method is fully parallel and scales to hundreds of processors. Several optimizations of the Common
Research Model wing-body-tail configuration are performed using the meshes generated by our technique.
We compare the best drag reduction obtained from multiblock and overset meshes using two
different artificial dissipation schemes. The smooth, highly orthogonal overset meshes produce better
results than the multiblock meshes, by up to 3 drag counts. An application to rotorcraft design is also
presented. The demonstrated meshing flexibility and accurate transonic solutions make the overset
mesh technique ideally suited for aerodynamic shape optimization.
analyze the effects of a leading-edge slat on rotor performance. The multielement intermesh connectivity was handled
by implicit hole cutting overset implementation. The three-dimensional coupled computational fluid dynamics/
computational structural dynamics model is extensively validated against a UH-60 flight-test condition: C9017. The
solver is then used to successfully demonstrate the effectiveness of a leading-edge slat in mitigating (or eliminating)
dynamic lift and moment stall on a modified UH-60A blade with a 40%-span slatted airfoil section. This results in a
reduction of torsional structural loads (up to 73%) and pitch link loads (up to 62%) as compared to the baseline C9017
values. A dynamically moving slat strategy, actuating between slat positions S-1 and S-6 with 1 per revolution
harmonic, is considered for stall mitigation. Further, it is shown that using slats with up to 10% higher thrust beyond
the limit imposed by McHugh’s stall boundary (C9017) can be achieved. Stall mitigation due to the slat results in a
reduction of torsional load up to 54% and a reduction of pitch link load up to 32% as compared to the baseline C9017
flight-test values, even for an increase in thrust of 10%.
problems is presented in this paper. The hybrid aeroacoustic approach, in which a near
body CFD solver is coupled to an FW-H acoustic module that propagates the rotor noise
signature to a far field observer, has been followed in this work. Both forward and adjoint
sensitivity formulations are derived that correspond to analogues of the aeroacoustic
analysis problem. The fully coupled aeroacoustic analysis formulation is first verified to
effectively perform noise predictions of a four bladed HART2 rotor in trimmed forward flight.
Upon successful verification, the adjoint formulation is used to minimize helicopter rotor
noise signatures via blade shape optimization.
which is particularly advantageous for aerodynamic design optimization, where hundreds of flow solutions
are required. However, generating body-fitted multiblock meshes for complex geometries is
challenging and is a time consuming task. The overset mesh technique greatly reduces the manual effort
required to generate meshes over complex geometries by overlapping a series of simpler meshes.
However, generating the necessary connectivity information between meshes in a robust and computationally
efficient manner remains a challenge. We address this challenge by developing an efficient
parallel overset grid assembly technique based on implicit hole cutting that is fully automatic. The
method is fully parallel and scales to hundreds of processors. Several optimizations of the Common
Research Model wing-body-tail configuration are performed using the meshes generated by our technique.
We compare the best drag reduction obtained from multiblock and overset meshes using two
different artificial dissipation schemes. The smooth, highly orthogonal overset meshes produce better
results than the multiblock meshes, by up to 3 drag counts. An application to rotorcraft design is also
presented. The demonstrated meshing flexibility and accurate transonic solutions make the overset
mesh technique ideally suited for aerodynamic shape optimization.
analyze the effects of a leading-edge slat on rotor performance. The multielement intermesh connectivity was handled
by implicit hole cutting overset implementation. The three-dimensional coupled computational fluid dynamics/
computational structural dynamics model is extensively validated against a UH-60 flight-test condition: C9017. The
solver is then used to successfully demonstrate the effectiveness of a leading-edge slat in mitigating (or eliminating)
dynamic lift and moment stall on a modified UH-60A blade with a 40%-span slatted airfoil section. This results in a
reduction of torsional structural loads (up to 73%) and pitch link loads (up to 62%) as compared to the baseline C9017
values. A dynamically moving slat strategy, actuating between slat positions S-1 and S-6 with 1 per revolution
harmonic, is considered for stall mitigation. Further, it is shown that using slats with up to 10% higher thrust beyond
the limit imposed by McHugh’s stall boundary (C9017) can be achieved. Stall mitigation due to the slat results in a
reduction of torsional load up to 54% and a reduction of pitch link load up to 32% as compared to the baseline C9017
flight-test values, even for an increase in thrust of 10%.