An Experimental Investigation of Full-Coverage Film Cooling Effectiveness and Heat Transfer Coefficient of a Turbine Guide Vane in a Linear Transonic Cascade

2016 ◽  
Author(s):  
Zhong-yi Fu ◽  
Hui-ren Zhu ◽  
Cun-liang Liu ◽  
Cong Liu ◽  
Zheng Li
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Film Cooling ◽  
Rate Ratio ◽  
Flow Rate Ratio ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Mass Flow Rate Ratio

This paper experimentally investigates the film cooling performance of an enlarged turbine guide vane with full-coverage cylindrical hole film cooling in short duration transonic wind tunnel which can model realistic engine aerodynamic conditions and adjust inlet Reynolds number and isentropic exit Mach number independently. The effects of mass flow rate ratio (MFR=4.83%∼8.83%), inlet Reynolds number (Rein= 1.7×105∼5.7×105), and isentropic exit Mach number (Mais=0.81∼1.01) are investigated. There are five rows of cylindrical film cooling holes on the pressure side and four such rows on the suction side respectively. Another four rows of cylindrical holes are provided on the leading edge to obtain a showerhead film cooling. The surface heat transfer coefficient and adiabatic film cooling effectiveness are derived from the surface temperatures measured by the thermocouples mounted in the middle span of the vane surface based on transient heat transfer measurement method. Mass flow rate ratio is shown to have a significant effect on film cooling effectiveness. The increase of mass flow rate ratio increases film cooling effectiveness on pressure side, while increasing this factor has opposite effect on film cooling effectiveness on the suction side. At the same mass flow rate ratio, increasing the Reynolds number can enhance the film cooling performance, the expectation is that at low mass flow rate ratio condition increasing the Reynolds number decreases film cooling effectiveness on the pressure side. The heat transfer coefficient increases with the mass flow rate ratio increasing on both pressure and suction side. At middle and high inlet Reynolds number condition, in the region of 0.4<s<0.6 on suction side, the coolant weakens heat transfer adversely.

scholarly journals Aerodynamic Loss Increase due to Individual Film Cooling Injections From Gas Turbine Nozzle Surface

1998 ◽  
Author(s):  
Ryo Kubo ◽  
Fumio Otomo ◽  
Yoshitaka Fukuyama ◽  
Yuhji Nakata
Keyword(s):  
Gas Turbine ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Pressure Loss ◽  
Rate Ratio ◽  
Flow Rate Ratio ◽  
Design Stage ◽  
Pressure Side ◽  
Mass Flow Rate Ratio

A CFD investigation was conducted on the total pressure loss variation for a linear nozzle guide vane cascade of a gas turbine, due to the individual film injections from the leading edge shower head, the suction surface, the pressure surface and the trailing edge slot. The results were compared with those of low speed wind tunnel experiments. A 2-D Navier-Stokes procedure for a 2-D slot injection, which approximated a row of discrete film holes, was performed to clarify the applicable limitation in the pressure loss prediction during an aerodynamic design stage, instead of a costly 3-D procedure for the row of discrete holes. In mass flow rate ratios of injection to main flow from 0% to 1%, the losses computed by the 2-D procedure agreed well with the experimental losses except for the pressure side injection cases. However, as the mass flow rate ratio was increased to 2.5%, the agreement became insufficient. The same tendency was observed in additional 3-D computations more closely modeling the injection hole shapes. The summations of both experimental and computed loss increases due to individual row injections were compared with both experimental and computed loss increases due to all-row injection with the mass flow rate ratio ranging from 0% to 7%. Each summation agreed well with each all-row injection result. Agreement between experimental and calculated results was acceptable. Therefore, the loss due to all-row injections in the design stage can be obtained by the correlations of 2-D calculated losses from individual row injections. To improve more precisely the summation prediction for the losses due to the present all-row injections, extensive research on the prediction for the losses due to the pressure side injection should be carried out.

A One-Dimensional Analytical Method for Turbine Blade Preliminary Cooling Design

2016 ◽  
Author(s):  
Chen Li ◽  
Jian-jun Liu
Keyword(s):  
Mass Flow Rate ◽  
Turbine Blade ◽  
Mass Flow ◽  
Flow Rate ◽  
Film Cooling ◽  
Three Dimensional ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
One Dimensional ◽  
Cooling Design

The turbine blade cooling design is a complex procedure including one-dimensional preliminary cooling design, detailed two-dimensional design and fluid network analyses, and three-dimensional conjugate heat transfer and FEM predictions. Frequent alteration and modification of the cooling configurations make it unpractical to obtain all of three-dimensional design results quickly. Preliminary cooling design deals mainly with the coolant requirements and can be knitted into fluid network to look up the expected cooling structural style to promote three-dimensional geometry design. Previous methods to estimate the coolant requirements of the whole turbine blade in the preliminary cooling design were usually based on the semi-empirical air-cooled blade data. This paper combines turbine blade internal and external cooling, and presents a one-dimensional theoretical analytical method to investigate blade cooling performance, assuming that the coolant temperature increases along the blade span. Firstly, a function of non-dimensional cooling mass flow rate is derived to describe the new relationship between adiabatic film cooling effectiveness and overall cooling effectiveness. Secondly, a new variable related to film cooling is found to estimate the required adiabatic film cooling effectiveness without using the empirical correlations. Finally, a theoretical calculation about the relationship between non-dimensional cooling mass flow rate and overall cooling effectiveness well corresponds to semi-empirical air-cooled blade data within regular range of cooling efficiency. The currently proposed method is also a useful tool for the blade thermal analysis and the sensitivity analysis of coolant requirements to various design parameters. It not only can provide all the possible options at the given gas and coolant inlet temperatures to meet the design requirement, but also can give the third boundary conditions for calculating the blade temperature field. It’s convenient to use the heat transfer characteristic of internal cooling structures to estimate the coolant mass flow rate and the channel hydraulic diameter for both convection cooling and film cooling.

Maximum Power Extraction From a Hot Stream in the Presence of Phase Change Under Limiting Collecting Temperatures

Volume 3 ◽  
2004 ◽  
Author(s):  
Juan C. Ordonez ◽  
Sheng Chen
Keyword(s):  
Phase Change ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Rate Ratio ◽  
System Structure ◽  
Constructal Theory ◽  
Flow Rate Ratio ◽  
Power Extraction ◽  
Mass Flow Rate Ratio

In this paper we consider the fundamental problem of maximizing the power extraction from a hot stream when the collecting stream experiences a phase change and there are limits imposed by the materials on the operating temperatures. It constitutes an extension of [4] where it was pointed out the existence of an optimal mass flow rate ratio of the hot stream to the collecting stream. In this work, we study the effects of the restrictions imposed by limiting temperatures on the spatial configuration, power extraction and the optimal matching of the two streams. An optimal hot-stream-to-collecting-stream mass flow rate ratio can be found when the collecting stream experiences a phase change while in contact with the hottest section of the hot stream. Associated to the optimal mass flow rate ratio there is also an optimal heat exchanger area allocation. The effects of several operating parameters on the optimal configuration are documented. This paper constitutes an illustration of how thermodynamic optimization leads to the discovery of system structure (constructal theory [1]).

Film Cooling Performance Improvement With Optimized Hole Arrangements on Pressure Side Surface of Nozzle Guide Vane: Part II — Experimental Validation

2016 ◽  
Author(s):  
Dong-Ho Rhee ◽  
Young Seok Kang ◽  
Bong Jun Cha ◽  
Jeong-Seek Kang ◽  
Sanga Lee ◽  
...  
Keyword(s):  
Mass Flow Rate ◽  
Performance Improvement ◽  
Mass Flow ◽  
Flow Rate ◽  
Film Cooling ◽  
Side Surface ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Percentage Points ◽  
Nozzle Guide

In the present study, the optimized configurations of film cooled turbine guide vanes proposed in Part I were validated experimentally and the effect of coolant mass flow rate on the performance was examined for those optimized configurations. A set of tests were conducted using an annular sector transonic turbine cascade test facility in Korea Aerospace Research Institute. The mainstream and the secondary air for cooling are supplied by 500 hp and 50 hp compressors, respectively, and the mainstream was heated approximately 20°C above the secondary flow by 300kW heater. To measure the film cooling effectiveness on the pressure side surface, the transient measurement method was used using a FLIR infrared camera system. The test section has five nozzle guide vanes with four passages. The three times scaled-up vane model is manufactured by a stereolithography method. The tests were conducted at mainstream exit Reynolds number based on the chord of 2.2×106 and the coolant mass flow rate ranging from 5 to 13% of the mainstream. The flow periodicity in the cascade passage was verified by surface static pressure measurements. The results showed that the optimized cases present better cooling effectiveness values in the overall region. The effect of coolant mass flow rate also presents the same trend. Comparison with the CFD results shows that the CFD results over-predict film cooling effectiveness by 10∼20 percentage points for baseline and 17∼23 percentage points for the optimized cases. This is probably partly due to the discrepancy of operating conditions such as inlet boundary condition and density ratio and partly due to the limitation of numerical method used in the optimization such as coarse grid near the surface. However, a quite good agreement is obtained qualitatively, which means the optimization process can be utilized as a reliable and efficient method for film cooling performance improvement.

Numerical Study of Supersonic Film Cooling in Diverging Section of Nuclear Rocket Laval Nozzle

2018 ◽  
Author(s):  
Xiaokai Sun ◽  
Ping Ye ◽  
Peixue Jiang ◽  
Wei Peng ◽  
Jie Wang
Keyword(s):  
Mach Number ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Film Cooling ◽  
Laval Nozzle ◽  
Numerical Study ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Nuclear Rocket

Nuclear rockets with specific impulse have obvious advantages by greatly reducing the mass of the propellant and potentially decreasing the cost of launching material from the earth’s surface. Nuclear thermal rockets use hydrogen propellant with coolant exit temperature of near 3000 K, which is very high, so the cooling of airframe surfaces in the vicinity of the exhaust is needed, of which film cooling is an effective method. Most of previous studies mainly focus on the film cooling effectiveness using two dimensional backward-facing step model, however, the nuclear rocket exhaust using the converging-diverging Laval nozzle, so the film cooling would be different. The present study numerically investigated the influence of coolant Mach number, coolant inlet height on supersonic film cooling in the diverging section of Laval nozzle, while keeping the coolant mass flow rate constant, with the results showing that: increasing the coolant inlet Mach number and the coolant inlet height can increase the film cooling effectiveness; for the same coolant mass flow rate, reducing the coolant inlet height and increasing the inlet Mach number improves film cooling effectiveness.

Influence of Coolant Jet Pulsation on the Convective Film Cooling of an Adiabatic Wall

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Qaiser Sultan ◽  
Gildas Lalizel ◽  
Matthieu Fénot ◽  
Eva Dorignac
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Film Cooling ◽  
Convective Heat Transfer Coefficient ◽  
Time Interval ◽  
Adiabatic Wall ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
The Impact

This study investigates the effects of sinusoidal pulsations externally imposed to an oblique round jet. The effectiveness of film coverage of an adiabatic wall onset for a thermally uniform bulk flow is presented in the perspective of gas turbine film cooling. For the injectant fluid, both the temperature and the mass flow rate are controlled prior to entrance to the periodic forcing system using a loudspeaker drive. The characteristic film cooling parameters including the blowing ratios and the temperature ratio are maintained at M=ρiUi/ρ∞U∞ = 0.65, 1, and 1.25, and Ti/T∞=2 respectively. The injection fluid is pulsated to a nondimensionalized frequency of St=f⋅d/U = 0, 0.2, 0.3, and 0.5. In the present investigation, the impact of injectant film modulation is figured out by analyzing the velocity fields measured by a system of time-resolved particle image velocimetry (TR-PIV), as well as analyzing the adiabatic wall temperature and the convective heat transfer coefficient measured by a system of infrared thermography. The overall film-cooling effectiveness is revealed by the time-averaged analysis, in which altered time-averaged jet trajectories and wake behavior are focused. It is observed that the pulsations tend to result in lower effectiveness when the flow remained attached to the wall in steady blowing case. In steady blowing cases with jet liftoff, such as for M= 1.25, rendering low-frequency pulsation helps in increasing film-cooling effectiveness due to the discharge of lower mass flow rate coolant during the significant time interval of the respective pulse cycle.

Sign in / Sign up

Export Citation Format

Share Document