An Experimental Investigation of Response of a Turbojet Engine to Inlet Distortion

A study of the response of a turbojet engine to the steady-state and the turbulence-type dynamic inlet distortion is presented in this paper. The steady-state distortion is generated by a 180° extent, 36 mesh screen, and the turbulence-type dynamic distortion by a 180° extent plate with 50% blockage ratio at the engine face. This plate can produce a very strong pressure fluctuation at the engine face. The statistical analysis shows that the APD of pressure fluctuation follows approximately the Normal Distribution except those cases near rotating stall or surge. Results from testing show: 1) inlet distortion generated by screen will produce a classical-surge or deep-surge (defined in ref. 1); 2) the degree of distortion by screen can change the mode of surge, e.g. from the classical-surge to the deep-surge and vice versa; 3) both the inlet distortion and the decrease in first-stage-turbine-nozzle area will change the compressor performance maps; 4) the turbulence-type dynamic distortion causes a “drift-surge” (defined in ref. 2).

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Inducer Stall in a Centrifugal Compressor With Inlet Distortion

Journal of Turbomachinery ◽

10.1115/1.3262066 ◽

1987 ◽

Vol 109 (1) ◽

pp. 27-35 ◽

Cited By ~ 8

Author(s):

I. Ariga ◽

S. Masuda ◽

A. Ookita

Keyword(s):

Flow Rate ◽

Centrifugal Compressor ◽

Stability Margin ◽

Rotating Stall ◽

Characteristic Parameters ◽

Inlet Distortion ◽

Rate Region ◽

Compressor Performance ◽

The Stability ◽

Lower Flow Rate

The effects of inlet distortion on the inducer stall in a centrifugal compressor are investigated. Cases of both radial and circumferential distortion are investigated. It is shown that the rotating stall onset is amplified by radial distortions, and restrained by circumferential distortions. These results are compared with calculations based on the small disturbance theory. The authors find that the stall onset is governed by the characteristic parameters related to the lower flow rate region for radial distortions, but affected by those of the higher flow rate region for circumferential distortion. It is shown that the process of stall is different for each distortion pattern. Existence of inlet distortion reduces compressor performance characteristics and strongly influences the stability margin.

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A Method for Evaluating the Effect of Circumferential Inlet Distortion on the Aerodynamic Stability of Multi-Stage Axial-Flow Compressors

Volume 7: Turbomachinery, Parts A, B, and C ◽

10.1115/gt2010-23541 ◽

2010 ◽

Author(s):

Tsuguji Nakano ◽

Andy Breeze-Stringfellow

Keyword(s):

Steady State ◽

High Speed ◽

Axial Flow ◽

Pressure Rise ◽

Stability Limit ◽

Rotating Stall ◽

Classical Dynamic ◽

Inlet Flow ◽

Inlet Distortion ◽

Multi Stage

A simple engineering parameter to evaluate the stability of high-speed multi-stage compressors with distorted inlet flow has been derived based on a simplified semi-compressible linear stability model. The parameter consists of steady-state flow quantities and geometric parameters of the compressor and it indicates that the circumferential integral of the slope of the steady-state individual blade row static pressure rise characteristics is important in the determination of the compressor stability limit in the presence of distortion. The parameter reduces to the author’s rotating stall inception parameter in the limit of non-distorted inlet flow. Since the model includes a downstream plenum and throttle, a condition for pure surge inception with undistorted inlet flow has been deduced. The pure surge conditions can be reduced to the classical dynamic and static instability conditions in the limit of a constant annulus area incompressible compressor. The results indicate that rotating stall always precedes surge instability, as many engineers and researchers would expect from experience. The parameter for instability with inlet distortion was calculated using test data measured in a high-speed 5-stage compressor with two different types of circumferential inlet distortion, and the results show that the parameter has a strong correlation with the data and is an improvement over the classical incompressible stability parameter. The results demonstrate that the parameter captures much of the physics important during the instability inception in a high-speed multi-stage compressor subjected to circumferential inlet distortion. The parameter clearly shows how each compressor component’s characteristics contribute to the overall stability in a high speed axial multi-stage compressor, therefore, it will aid engineers and designers in their understanding and prediction of the aerodynamic instability inception phenomena.

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Prediction and Evaluation of Waterjet Pump Performance under Nonuniform Inflow Using Parallel Compressor Theory

Water ◽

10.3390/w13010099 ◽

2021 ◽

Vol 13 (1) ◽

pp. 99

Author(s):

Puyu Cao ◽

Rui Zhu

Keyword(s):

Flow Instability ◽

Internal Flow ◽

Weighted Sum ◽

Pump Performance ◽

Inlet Velocity ◽

Inlet Distortion ◽

Pump Head ◽

Compressor Performance ◽

Waterjet Pump ◽

External Characteristics

Parallel compressor theory (PCT) is commonly used to estimate effects of inlet distortion on compressor performance. As well as compressor, the actual inflow to pump is also nonuniform and unfavorable for performances. Nowadays, insufficient understanding of nonuniform inflow effects on pump performance restricts its development. Therefore, this paper applies PCT to predict external characteristics and evaluate internal flow instability of waterjet pump under nonuniform inflow. According to features of nonuniform inflow, the traditional PCT is modified and makes waterjet pump sub-divided into two circumferential tubes owning same performances but with different inlet velocity (representing nonuniform inflow). Above all, numerical simulation has been conducted to validated the applicability and accuracy of PCT in head prediction of waterjet pump under nonuniform inflow, since area-weighted sum of each tube head (i.e., theoretical pump head) is highly consistent with simulated result. Moreover, based on identifications of when and which tube occurs stall, PCT evaluates four stall behaviors of waterjet pump: partial deep stall, partial stall, pre-stall and full stall. Furthermore, different stall behavior generates different interactions between head variation of each tube, resulting in a multi-segment head curve under nonuniform inflow. The modified PCT with associated physical interpretations are expected to provide a sufficient understanding of nonuniform inflow effects on pump performances.

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Experimental investigation of a model bulb turbine under steady state and load rejection process

Renewable Energy ◽

10.1016/j.renene.2021.01.014 ◽

2021 ◽

Author(s):

Huixiang Chen ◽

Daqing Zhou ◽

Kan Kan ◽

Hui Xu ◽

Yuan Zheng ◽

...

Keyword(s):

Experimental Investigation ◽

Steady State ◽

Load Rejection Process ◽

Bulb Turbine

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Experimental investigation and modelling of continuous fluidized bed drying under steady-state and dynamic conditions

Chemical Engineering Science ◽

10.1016/s0009-2509(02)00424-4 ◽

2002 ◽

Vol 57 (24) ◽

pp. 5021-5038 ◽

Cited By ~ 55

Author(s):

J. Burgschweiger ◽

E. Tsotsas

Keyword(s):

Experimental Investigation ◽

Steady State ◽

Fluidized Bed ◽

Dynamic Conditions ◽

Fluidized Bed Drying

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Recess Vane Passive Stall Control

Volume 1: Turbomachinery ◽

10.1115/92-gt-036 ◽

1992 ◽

Cited By ~ 4

Author(s):

M. Ziabasharhagh ◽

A. B. McKenzie ◽

R. L. Elder

Keyword(s):

Experimental Investigation ◽

Axial Flow ◽

Operating Efficiency ◽

Stall Margin ◽

Casing Treatment ◽

Inlet Distortion ◽

Stall Margin Improvement ◽

Stage Characteristic ◽

Stall Control

An experimental investigation has been carried out on the influence of a vaned recessed casing treatment on the stall margin improvement of axial flow fans with different hub to tip ratio, with and without inlet distortion. The inlet distortion tests were conducted on a 0.5 hub to tip ratio fan and significant increases in the flow range with only small drops in operating efficiency were observed. The clean flow tests were conducted on higher hub to tip ratio fans (0.7 and 0.9). In each case the stage characteristic was compared with the results obtained with a solid casing. Significant increases in the flow range, with only modest or no loss in operating efficiency, were observed for optimum configurations at both diameter ratios.

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Application of a Fuzzy Logic Controller for Speed Control on a Small-Scale Turbojet Engine

Volume 1B: Marine; Microturbines, Turbochargers and Small Turbomachines; Steam Turbines ◽

10.1115/gt2014-27158 ◽

2014 ◽

Author(s):

Serdar Üşenmez ◽

Sinan Ekinci ◽

Oğuz Uzol ◽

İlkay Yavrucuk

Keyword(s):

Fuzzy Logic ◽

Steady State ◽

Transient Response ◽

Fuzzy Logic Controller ◽

Electronic Control Unit ◽

Small Scale ◽

Gas Temperature ◽

Fuel Pump ◽

Fuel Flow ◽

Turbojet Engine

Having a small-scale turbojet engine operate at a desired speed with minimum steady state error, while maintaining good transient response is crucial in many applications, such as UAVs, and requires precise control of the fuel flow. In this paper, first the mathematical model of a Small-Scale Turbojet Engine (SSTE) is obtained using system identification tests, and then based on this model, a classical PI controller is designed. Afterwards, to improve on the transient response and steady state performance of this classical controller, a Fuzzy Logic Controller (FLC) is designed. The design process for the FLC employs logical deduction based on knowledge of the engine behavior and iterative tuning in the light of software- and hardware-in-the-loop simulations. The classical and fuzzy logic controllers are both implemented on an in-house, embedded Electronic Control Unit (ECU) running in real time. This ECU is an integrated device carrying a microcontroller based board, a fuel pump, fuel line valves, speed sensor and exhaust gas temperature sensor inputs, and starter motor and glow plug driver outputs. It mainly functions by receiving a speed reference value via its serial communication interface. Based on this reference, a voltage is calculated and applied to the fuel pump in order to regulate the fuel flow into the engine, thereby bringing the engine speed to the desired value. Pre-defined procedures for starting and stopping the engine are also automatically performed by the ECU. Further, it connects to a computer running an in-house comprehensive Graphical User Interface (GUI) software for operating, monitoring, configuration and diagnostics purposes. The designed controllers are used to drive a generic SSTE. Reference inputs consisting of step, ramp and chirp profiles are applied to the controllers. The engine response using both controllers are recorded and inspected. The results show that the FLC exhibits a comparable performance to the classical controller, with possible opportunities to improve this performance.

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