{"references": ["[1] Srinivasan, A.V., (1997), Flutter and resonant vibration characteristics of engine blades. Journal of Engineering for Gas Turbines and Power. Transactions of the ASME, vol 119(4), p. 742 - 775. doi:10.1115/1.2817053.", "[2] Schoenenborn, H ., (2017), Analysis of the effect of multi - row and multi - passage aerodynamic interaction on the forced response variation in a compressor configuration - Part 1 - Aerodynamic excitation . Proceedings of the A SME Turbo Expo: Turbine Technical Conference and Exposition, Volume 7B: Structures and Dynamics . doi :10.1115/GT2017 - 63018", "[3] Gross, J., Krack M., Schoenenborn, H ., (2017), Analysis of the effect of multi - row and multi - passage aerodynamic interaction on the forced response variation in a compressor configuration - Part 2 - Effect of additional Structural Mistuning. Proceedings of the A SME Turbo Expo: Turbine Technical Conference and Exposition, 2017 . Volume 7B: Structures and Dynamics . doi:10.1115/GT2017 - 63019.", "[4] Vilmin S . S ., Lorrain E . E ., Hirsch C .H ., (2009), Application of a Nonlinear Harmonic Method to the Simulation of Clocking Effects . Proceedings of the A SME Turbo Expo: Turbine Technical Conference and Exposition, vol 7 Pt A and B . doi:10.1115/GT2009 - 59475.", "[5] Besem F.M., Kielb R.E., Galpin, P., Zori, L ., Key, N.L., (2016), Mistuned Forced Response Predictions of an Embedded Rotor in a Multistage Compressor . Journal of Turbomachinery - Transactions of the ASME . vol 1 3 8 (6 ), pp. 106 - 115 . doi:10.1115/1.4032164", "[6] Besem F . M ., Kielb R . E ., Key N . L ., (2015), Forced Response Sensitivity of a Mistuned Rotor from an Embedded Compressor Stage. Journal of Turbomachinery - Transactions of the A SME, vol 138(3 ). Pp, 103 - 113. doi:10.1115/1.4031866", "[7] L i, J., and Kielb. R., (2017), Forcing Superposition and Decomposition of an Embedded Compressor Rotor, Proceedings of the A SME Turbo Expo: Turbine Technical Conference and Exposition, 2017, Vol 7 B . doi:10.1115/GT2017 - 64657", "[8] Owczarek J . A., (2011), On the Phenomenon of Pressure Pulses Reflecting Between Adjacent Blade Rows of Turbomachines. ASME Journal of turbomachinery, vol 133, pp 162 - 171 . doi:10.1115/1.4001185", "[9] Owczarek J . A ., (1984), Analysis of an Axial Compressor Blade Vibration Based on Wave Reflection Theory . ASME. J. Eng. Gas Turbines Power, vol 106(1), pp 57 - 64. doi:10.1115/1.3239551.", "[10] Kielb R. and Kaza, K. (1983), Aeroelastic characteristics of a cascade of mistuned blades in subsonic and supersonic flows, J. Vibration Acoustics ., vol 105, pp 425 - 433. doi:10.1115/1.3269124", "[11] Joshua J Waite. (2016), Physical effects, Steady Aerodynamic effects and a design tool for low pressure turbine flutter, Duke University", "[12] Hall, K.C., and Hall, S. R., ( 2016 ), Private communication", "[13] Giles, M., ( 1988 ), Calculation of Unsteady Wake/Rotor Interaction . Journal of Propulsion & Power, pp. 356 - 362", "[14] ANSYS CFX R18.0 (2017), Help manual, ANSYS Inc", "[15] Qizar, M ., Mansour, M ., Goswami, S ., ( 2013 ), Study of Steady State and Transient Blade Row CFD Methods in a Moderately Loaded NASA Transonic High - Speed Axial Compressor Stage. Proceedings of ASME Turbo Expo, 2013/ GT2013 - 94739", "[16] Zori, L., Galpin, P., Campregher, R., Morales, J.C., ( 2 0 1 5 ), Time - Transformation Simulation of a 1.5 Stage Transonic Compressor, Journal of Turbomachinery, Vol 139, no. 7, pp. 1139 - 115 2"]}

The forced response behaviour of a rotor in a 3.5 - stage compressor rig is studied in this paper. Previous study indicates that the unsteady wave reflection level can highly influence forced response prediction results. Though traditional non - reflecting boundary conditions or mesh treatments can reduce the reflecting waves in the calculation efficiently, in physics the waves will reflect when interacting with the up - and downstream unstimulated bladed rows and non - reflecting is still an approximation. The downstream reflection was identified to have significant influence on the unsteady pressure of the simulated domains. Thus, the aim of this paper is to investigate the potential reflection effect and the consequent influence of forced response due to bladed rows. As an extension of our 3 - row stator - rotor - stator (S1 - R2 - S2) forced response simulation, a 4 - row (S1 - R2 - S2 - R3) simulation is conducted to test the influence of 1T - 44EO wave reflected from R3 back to R2 domain . Difference is seen compared with the case without the R3 domain, and a destructive interference is observed on forced response behaviours. Two conclusions are drawn from this study: 1) Wave excitation created by downstream stator s can reflect upstream due to the existence of the rotor row further downstream. The excitation interacts with the two traditional excitation sources, wake and potential field. In this case, the interaction is destructive and leads to a lower modal force prediction. 2) This reflection from down - stream row has a significant influence on the prediction of forced response, whereas upstream reflection is not significant. 3) The cut - on nature of the wave in this case also contributes to the reflection, as the wav e propagates without deterioration. This research also provides a guidance of forced response multi - row modeling.