Optimal detailed design and performance assessment of natural gas pressure reduction stations system equipped with variable inlet guide vane radial turbo-expander for energy recovery

Author(s):  
Farzaneh Rezaei ◽  
Seyed Mohammad Ebrahimi Saryazdi ◽  
Yadollah Saboohi
Aerospace ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 172
Author(s):  
Hengtao Shi

Recently, a new type of low-loss variable inlet guide vane (VIGV) was proposed for improving a compressor’s performance under off-design conditions. To provide more information for applications, this work investigated the effect of the Reynolds number and clearance flow on the aerodynamic characteristics of this new type of VIGV. The performance and flow field of two representative airfoils with different chord Reynolds numbers were studied with the widely used commercial software ANSYS CFX after validation was completed. Calculations indicate that, with the decrease in the Reynolds number Rec, the airfoil loss coefficient ω and deviation δ first increase slightly and then entered a high growth rate in a low range of Rec. Afterwards, a detailed boundary-layer analysis was conducted to reveal the flow mechanism for the airfoil performance degradation with a low Reynolds number. For the design point, it is the appearance and extension of the separation region on the rear portion; for the maximum incidence point, it is the increase in the length and height of the separation region on the former portion. The three-dimensional VIGV research confirms the Reynolds number effect on airfoils. Furthermore, the clearance leakage flow forms a strong stream-wise vortex by injection into the mainflow, resulting in a high total-pressure loss and under-turning in the endwall region, which shows the potential benefits of seal treatment.


Author(s):  
Kamal Abudu ◽  
Uyioghosa Igie ◽  
Orlando Minervino ◽  
Richard Hamilton

With the transition to more use of renewable forms of energy in Europe, grid instability that is linked to the intermittency in power generation is a concern, and thus, the fast response of on-demand power systems like gas turbines has become more important. This study focuses on the injection of compressed air to facilitate the improvement in the ramp-up rate of a heavy-duty gas turbine. The steady-state analysis of compressed airflow injection at part-load and full load indicates power augmentation of up to 25%, without infringing on the surge margin. The surge margin is also seen to be more limiting at part-load with maximum closing of the variable inlet guide vane than at high load with a maximum opening. Nevertheless, the percentage increase in the thermal efficiency of the former is slightly greater for the same amount of airflow injection. Part-load operations above 75% of power show higher thermal efficiencies with airflow injection when compared with other load variation approaches. The quasi-dynamic simulations performed using constant mass flow method show that the heavy-duty gas turbine ramp-up rate can be improved by 10% on average, for every 2% of compressor outlet airflow injected during ramp-up irrespective of the starting load. It also shows that the limitation of the ramp-up rate improvement is dominated by the rear stages and at lower variable inlet guide vane openings. The turbine entry temperature is found to be another restrictive factor at a high injection rate of up to 10%. However, the 2% injection rate is shown to be the safest, also offering considerable performance enhancements. It was also found that the ramp-up rate with air injection from the minimum environmental load to full load amounted to lower total fuel consumption than the design case.


Author(s):  
David Händel ◽  
Reinhard Niehuis ◽  
Uwe Rockstroh

In order to determine the aerodynamic behavior of a Variable Inlet Guide Vane as used in multishaft compressors, extensive experimental investigations with a 2D linear cascade have been conducted. All the experiments were performed at the High-Speed Cascade Wind Tunnel at the Institute of Jet Propulsion. They covered a wide range of Reynolds numbers and stagger angles as they occur in realistic turbomachines. Within this work at first the observed basic flow phenomena (loss development, overturning) will be explained. For the present special case of a symmetric profile and a constant decreasing chord length along the vane height, statements about different spanwise position can be made by investigating different Reynolds numbers. The focus of this paper is on the outflow of the VIGV along the vane height. Results for an open flow separation on the suction side are presented, too. Stall condition can be delayed by boundary layer control. This is done using a wire to trigger an early boundary layer transition. The outcomes of the trip wire measurement are finally discussed. The objective of this work is to evaluate the influence of the stagger angle and Reynolds number on the total pressure losses and the deviation angle. The results of the work presented here, gives a better insight of the efficient use of a VIGV.


Author(s):  
Hans Ma˚rtensson ◽  
Jo¨rgen Burman ◽  
Ulf Johansson

As the first design in a demonstration program for future fighter engine fans a 400 mm 1-1/2 stage fan has been designed and built. A new method including mechanical constraints for designing the blades and gas path is used for the first time on a new design. The approach closely integrates CFD for performance and FE methods for the structure. By this, advanced computational analyses affect the design from the early stages. A design that is successful in achieving good efficiency based on CFD as well as reasonable aeromechanical properties based on FE is derived. The fan incorporates a front frame (FF), variable inlet guide vane (VIGV), rotor 1 (R1) and stator 1 (S1).


Author(s):  
Kirubakaran Purushothaman ◽  
N. R. Naveen Kumar ◽  
Vidyadheesh Pandurangi ◽  
Ajay Pratap

Abstract Variability in stator vanes is a widely used technique to improve the stability and efficiency of axial flow compressor in gas turbine engines. Most of the modern aircraft jet engines use variable stator vanes in both low pressure and high pressure compressors primarily for off-design performance. This study discusses in detail about the effect of stator variability in a three stage low pressure axial compressor at design and off-design conditions. Computational flow analysis were carried out for the three stage low pressure compressor with variability in inlet guide vane and first stage stator blade. Detailed investigation on flow physics was carried out in rotor blade passages with stator variability. At off-design speeds, the reduction in flow velocity is lower than the reduction in blade tip speed. This leads to mismatch in flow angles and inlet blade angles causing high incidence and large flow separation in blade passage. This results in poor aerodynamic stability of the axial compressor at off-design speeds. In this study, aerodynamic performance of compressor is evaluated from 70% to 100% design speeds with different stagger angle setting of inlet guide vane at each speed. Further, to improve 2nd stage rotor performance, variability was introduced in 1st stage stator blade and performance was evaluated. Compressor test results are compared with CFD data for design and off-design speeds.


Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4453 ◽  
Author(s):  
Piero Danieli ◽  
Gianluca Carraro ◽  
Andrea Lazzaretto

A big amount of the pressure energy content in the natural gas distribution networks is wasted in throttling valves of pressure reduction stations (PRSs). Just a few energy recovery systems are currently installed in PRSs and are mostly composed of radial turboexpanders coupled with cogeneration internal combustion engines or gas-fired heaters providing the necessary preheating. This paper clarifies the reason for the scarce diffusion of energy recovery systems in PRSs and provides guidelines about the most feasible energy recovery technologies. Nine thousand PRSs are monitored and allocated into 12 classes, featuring different expansion ratios and available power. The focus is on PRSs with 1-to-20 expansion ratio and 1-to-500 kW available power. Three kinds of expanders are proposed in combination with different preheating systems based on boilers, heat pumps, or cogeneration engines. The goal is to identify, for each class, the most feasible combination by looking at the minimum payback period and maximum net present value. Results show that small size volumetric expanders with low expansion ratios and coupled with gas-fired heaters have the highest potential for large-scale deployment of energy recovery from PRSs. Moreover, the total recoverable energy using the feasible recovery systems is approximately 15% of the available energy.


Author(s):  
Loc Q. Duong ◽  
Charlene X. Hu ◽  
Nagamany Thayalakhandan

The APU, a gas turbine engine is designed to provide the aircraft with electrical power and pneumatic air both on the ground and in-flight conditions. The variable inlet guide vane (VIGV) system is used to regulate the air flow to the load compressor. The vane motions are controlled by an actuator and associated linkage. Common failure mechanisms of the VIGV such as cracking, corrosion of vanes, have been reported. This paper discusses a particular mode of failure which involves the aero-mechanical and control feedback interaction. The failure phenomenon is characterized by sector and ring gear tooth non-uniform wear, jamming of sector gears, actuator resonance, actuator fluid contamination and subsequent engine shutdown. Solution to failure mode is also discussed.


Author(s):  
L Zhou ◽  
H-Z Fan ◽  
W Wei ◽  
Y-H Cai

The unsteady inlet guide vane (IGV)–impeller–diffuser interaction in a centrifugal compressor is investigated numerically and experimentally under different IGV prewhirl angles. The influence of IGV prewhirl angle on the flowfield and the unsteadiness of the impeller and diffuser are studied, and the mechanism of the unsteady IGV–impeller–diffuser interaction is explored. Results show that quite fair quantitative agreements are achieved between the predicted and measured flowfield. The IGV wake can decrease the unsteadiness on the impeller and diffuser, and the reduction of the unsteadiness caused by the IGV is a function of the IGV prewhirl angle. The unsteadiness in the diffuser with negative IGV angles is larger than that for positive prewhirl angles. The low-frequency oscillations inside the flowfield are induced by the IGV. When IGV prewhirl occurs, the basic frequency of the unsteady flow in the vaneless diffuser is mainly half of the blade passing frequency of the impeller. In practice, the IGV prewhirl angle can be adjusted to avoid unsteady vibrations in some off-design conditions, with reliability and performance improved simultaneously.


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