TY - JOUR

T1 - Effect of radial location of nozzles on performance of preswirl systems

T2 - a computational and theoretical study

AU - Lewis, Paul

AU - Wilson, Michael

AU - Lock, Gary D

AU - Owen, J M

PY - 2009/3/1

Y1 - 2009/3/1

N2 - This article investigates the effect of the radial location of the inlet nozzles on the performance of a direct-transfer preswirl system in a rotor-stator wheel-space. A commercial code is used to solve the Reynolds averaged Navier-Stokes equations using a high-Reynolds-number kappa-epsilon/kappa-omega turbulence model with wall functions. The three-dimensional steady-state model has previously been validated against experimental results from a scale model of a gas turbine rotor-stator system. Computations are performed for three inlet-to-outlet radius ratios, r(p)/r(b) = 0.8, 0.9, and 1.0, a range of preswirl ratios, 0.5 < beta(b) < 2.0, and varying turbulent flow parameters, 0.12 < gamma(T) < 0.36. The rotational Reynolds number for each case is 10(6). The flow structure in the wheel-space and in the region around the receiver holes for each inlet radius is related to the swirl ratio. The performance of the system is quantified by two parameters: the discharge coefficient for the receiver holes (C-d,C-b) and the adiabatic effectiveness for the system (Theta(b,ad)). As in previous work, the discharge coefficient is found to reach a maximum when the rotating core of fluid is in synchronous rotation with the receiver holes. As the radius ratio is increased, this condition can be achieved with a smaller value for preswirl ratio Ob. A simple model is presented to estimate the discharge coefficient based on the flowrate and swirl ratio in the system. The adiabatic effectiveness of the system increases linearly with preswirl ratio but is independent of flowrate. For a given preswirl ratio, the effectiveness increases as the radius ratio increases. Computed values show good agreement with analytical results. Both performance parameters show improvement with increasing inlet radius ratio, suggesting that for an optimum preswirl configuration an engine designer would place the preswirl nozzles at a high radius.

AB - This article investigates the effect of the radial location of the inlet nozzles on the performance of a direct-transfer preswirl system in a rotor-stator wheel-space. A commercial code is used to solve the Reynolds averaged Navier-Stokes equations using a high-Reynolds-number kappa-epsilon/kappa-omega turbulence model with wall functions. The three-dimensional steady-state model has previously been validated against experimental results from a scale model of a gas turbine rotor-stator system. Computations are performed for three inlet-to-outlet radius ratios, r(p)/r(b) = 0.8, 0.9, and 1.0, a range of preswirl ratios, 0.5 < beta(b) < 2.0, and varying turbulent flow parameters, 0.12 < gamma(T) < 0.36. The rotational Reynolds number for each case is 10(6). The flow structure in the wheel-space and in the region around the receiver holes for each inlet radius is related to the swirl ratio. The performance of the system is quantified by two parameters: the discharge coefficient for the receiver holes (C-d,C-b) and the adiabatic effectiveness for the system (Theta(b,ad)). As in previous work, the discharge coefficient is found to reach a maximum when the rotating core of fluid is in synchronous rotation with the receiver holes. As the radius ratio is increased, this condition can be achieved with a smaller value for preswirl ratio Ob. A simple model is presented to estimate the discharge coefficient based on the flowrate and swirl ratio in the system. The adiabatic effectiveness of the system increases linearly with preswirl ratio but is independent of flowrate. For a given preswirl ratio, the effectiveness increases as the radius ratio increases. Computed values show good agreement with analytical results. Both performance parameters show improvement with increasing inlet radius ratio, suggesting that for an optimum preswirl configuration an engine designer would place the preswirl nozzles at a high radius.

KW - computational fluid dynamics

KW - gas turbines

KW - discharge coefficients

UR - http://www.scopus.com/inward/record.url?scp=64249125605&partnerID=8YFLogxK

UR - http://dx.doi.org/10.1243/09576509jpe689

U2 - 10.1243/09576509jpe689

DO - 10.1243/09576509jpe689

M3 - Article

SN - 0957-6509

VL - 223

SP - 179

EP - 190

JO - Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy

JF - Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy

IS - 2

ER -