Paper 23: An Experimental Investigation of Non-Steady Flow in a Radial Gas Turbine

1965 ◽  
Vol 180 (10) ◽  
pp. 74-85 ◽  
Author(s):  
R. S. Benson ◽  
K. H. Scrimshaw
Keyword(s):  
Steady Flow ◽  
Mass Flow ◽  
Pulse Generator ◽  
Flow Analysis ◽  
Pulse Frequency ◽  
Exhaust Pipe ◽  
Transient Pressure ◽  
Radial Turbine ◽  
Admission Data ◽  
Partial Admission

Comprehensive steady and non-steady flow tests on a small radial turbine turbo-charger are given. Steady flow tests included both full admission and partial admission over the whole speed and pressure range from zero flow to maximum flow. Non-steady flow tests were carried out over a pulse frequency range from 30 to 70 pulses/s and turbine speeds from 30 000 to 60 000 rev/min with the turbine coupled to the exhaust system of a six-cylinder pulse generator under partial admission conditions. Extensive transient pressure and temperature measurements were taken upstream and downstream (pressure only) of the turbine. The total mass flow and power were also measured. A quasi-steady flow analysis was carried out using the steady flow test data. The tests results showed that for a six-cylinder exhaust pipe configuration, with two exhaust pipes entering separate nozzle segments in the radial turbine, the quasi-steady flow analysis using partial admission data grossly underestimated the mass flow and power output of the turbine. Using full admission data the ratio of measurement mass flow and horsepower to the calculated mass flow and horsepower was nearly always greater than unity. Furthermore, the average turbine efficiency was greater under non-steady flow than under steady flow. The magnitude of the recorded effects was dependent on the pulse frequency and turbine speed.

Performance of Radial Flow Turbines Under Pulsating Flow Conditions

1976 ◽  
Vol 98 (1) ◽  
pp. 53-59 ◽  
Author(s):  
H. Kosuge ◽  
N. Yamanaka ◽  
I. Ariga ◽  
I. Watanabe
Keyword(s):  
Steady Flow ◽  
Pressure Pulse ◽  
Radial Flow ◽  
Pressure Ratio ◽  
Pulse Frequency ◽  
Pulsating Flow ◽  
Frequency Range ◽  
Flow Conditions ◽  
Transient Pressure ◽  
Empirical Parameter

Investigations of the pulsating flow performances of an inward radial flow turbine were performed. The quasi-steady flow performances predicted from the measured transient pressure ratio and from steady flow performance data were compared with the measured mean performances under pulsating flow conditions over the pulse frequency range of 30 Hz–70 Hz. The validity of this quasi-steady flow assumption was treated more generally than by the hitherto employed method by adopting a new empirical parameter which indicates both the pressure pulse shape and the amplitude of pressure fluctuation, in addition to the pulse frequency.

Paper 21: A Quasi-Steady Flow Representation of Centrifugal Compressor Performance Characteristics in Non-Steady Flow Systems

1967 ◽  
Vol 182 (8) ◽  
pp. 197-208 ◽  
Author(s):  
R. S. Benson ◽  
A. Whitfield
Keyword(s):  
Steady Flow ◽  
Centrifugal Compressor ◽  
Pulse Generator ◽  
Reverse Flow ◽  
Pressure Ratio ◽  
Pulse Frequency ◽  
Rotary Valve ◽  
Pipe Length ◽  
Flow Through ◽  
Compressor Performance

This paper describes a theoretical and experimental study of the non-steady flow performance of a centrifugal compressor. The experimental work was designed to study the effect of pulse frequency on the compressor performance, for a given delivery configuration, using a rotary valve pulse generator. The experimental rig was designed so that it was possible to study the reverse flow and the pressure pulsations in the suction side of the compressor. The objective of the investigation was to discover how the compressor performance deteriorated with pulse frequency, and also to determine the frequency at which reverse flow through the compressor first occurred. The objective of the theoretical work was to predict the onset of reverse flow through the compressor and the mean and transient delivery pressure ratio using the conventional stationary pipe non-steady solutions by the method of characteristics. The compressor unit was replaced by a boundary condition within the pipe system equal to the experimentally known steady flow characteristics of the compressor. The physical size of the compressor was replaced by an equivalent pipe length; this technique is described. The theoretical results are compared with an extensive series of experimental results. This work is a direct extension of that given in reference (3).

scholarly journals INVESTIGATION OF CONJUGATED HEAT TRANSFER FOR A RADIAL TURBINE WITH IMPINGEMENT COOLING

2021 ◽  
Vol 2087 (1) ◽  
pp. 012037
Author(s):  
Han Zhang ◽  
Hua Chen ◽  
Chao Ma ◽  
Feng Guo
Keyword(s):  
Heat Transfer ◽  
Steady Flow ◽  
Mass Flow ◽  
Leading Edge ◽  
Inlet Temperature ◽  
Impingement Cooling ◽  
Radial Turbine ◽  
Turbine Inlet ◽  
Cooling Effects ◽  
Conjugated Heat Transfer

Abstract Radial turbine is widely used in micro-turbines, turbochargers, small jet engines and expanders, and the pursue of high system efficiency has resulted in elevated turbine inlet temperatures for some of its applications, threatening its reliability. There are, however, few cooling studies on radial turbines. This paper studies the jet impingement cooling of a turbocharger radial turbine. A small amount of air (coolant), which could come from compressor discharge cooled by an intercooler, is injected through a few jet holes on the heat shield of the turbine onto the upper part of turbine backdisc, to cool the rotor blades and the backdisc. Parameters that may affect the cooling were studied by a Conjugated Heat Transfer (CHT) numerical simulation using steady flow calculations. The influences to the cooling effects by different coolant-to-turbine mass flow ratios, Coolant-to-turbine inlet temperature ratio, number of the jets etc. were analysed by a steady flow simulation. The simulation results show that, when four jet holes are placed at blade leading edge radius, using 1.0% ~ 3.0% of the main gas mass flow of coolant, the average temperature on leading edge, inducer hub and backdisc surface is reduced by 2K ~ 17K,27K ~ 65K and 51K ~ 70K respectively. Turbine efficiency is mostly reduced little over 1% point.

scholarly journals Pubertal Acceleration of Pulsatile Gonadotropin-Releasing Hormone Release in Male Rats as Revealed by Microdialysis

Endocrinology ◽  
2003 ◽  
Vol 144 (1) ◽  
pp. 163-171 ◽  
Author(s):  
Glenn C. Harris ◽  
Jon E. Levine
Keyword(s):  
Vas Deferens ◽  
Pulse Generator ◽  
Pulse Amplitude ◽  
Pulse Frequency ◽  
Male Rats ◽  
Male Rat ◽  
Pubertal Maturation ◽  
Repeated Sampling ◽  
Generator Activity ◽  
Mature Spermatozoa

Abstract A microdialysis technique was used in male rats to directly assess the postulate that pubertal maturation is associated with accelerated GnRH pulsatility. Juvenile male rats, postnatal d 43 or 45 (n = 4) were stereotaxically fitted with guide cannulas directed toward the lateral median eminence, and repeated microdialysis experiments were conducted over 4–6 d. In each session, samples were collected continuously over 12 h (0900–2100 h) at 5-min intervals Results from individual peripubertal animals were pooled into two time bins for postnatal d 45–47 and 48–50, respectively, and GnRH characteristics were compared between the two epochs. The GnRH pulse frequency and mean GnRH concentration were significantly elevated at 48–50 d compared with 45–47 d. The GnRH pulsatility characteristics for 45–47 d vs. 48–50 d were as follows: pulse frequency, 0.74 ± 0.16 vs. 1.79 ± 0.19 pulses/h (P < 0.05); pulse amplitude, 254.1 ± 22.3 vs. 347.2 ± 15.8 Δpg/ml (difference in value from trough to peak); and mean release, 0.55 ± 0.03 vs. 2.04 ± 0.04 pg/5 min (P < 0.05). An additional two rats were dialyzed only once on postnatal d 50 to assess the effects of repeated sampling; the GnRH pulse characteristics in these animals were similar to those in rats sampled for a third or fourth time on postnatal d 48–50. To further assess the possible effects of repeated sampling on GnRH release profiles, a group of adult male rats (postnatal d 95–105; n = 3) was also dialyzed on four consecutive days. In these rats no significant alteration in GnRH pulse generator activity was observed over the four sessions. Moreover, the increase in GnRH pulse frequency observed in the peripubertal rats was found to be sustained in adult animals. To better understand the temporal relationship of GnRH pulse generator activity to reproductive maturation, groups of male rats were killed from postnatal d 45–56 along with an adult group at 95–105 d (n = 5/group) and examined for physiological signs of reproductive development. Gradual increases in serum levels of LH and testosterone and decreases in FSH and inhibin B were seen from postnatal d 45–56 to adulthood. Mature spermatozoa were found in the vas deferens by postnatal d 53. Our results demonstrate that in the late juvenile stage of male rat development, GnRH pulse generator activity is gradually accelerated over the course of consecutive days. This acceleration occurs over a period during which serum LH and testosterone are rising to adult levels, and it precedes the presence of mature spermatozoa in the vas deferens by 3 d. Our observations provide direct support for the hypothesis that an acceleration of GnRH pulsatility is the critical neural stimulus for the initiation of pubertal maturation in males. The peripheral and central cues that prompt the pubertal activation of the GnRH pulse generator remain to be characterized.

Autostoichiometric vapor deposition: Part I. Theory

1995 ◽  
Vol 10 (10) ◽  
pp. 2536-2541 ◽  
Author(s):  
Ren Xu
Keyword(s):  
Mass Flow ◽  
Vapor Deposition ◽  
Flow Analysis ◽  
Quantitative Measure ◽  
Low Pressure ◽  
Potential Candidate ◽  
Organic Complexes ◽  
Reaction Schemes

The possibility of an autostoichiometric vapor deposition is explored. Heterometal-organic complexes such as double alkoxides are potential candidate precursors for such deposition. Two reaction schemes, the hydrolysis-assisted pyrolysis and the hydrolysis-polycondensation of double alkoxides, are identified to be autostoichiometric reactions. A simple low-pressure apparatus is suggested for autostoichiometric vapor deposition. Mass-flow analysis allows for the identification of a nonstoichiometry factor K which can be used as a quantitative measure of the precursor's autostoichiometric capability.

Pulsatile LH secretion in streptozotocin-induced diabetes in the rat

1991 ◽  
Vol 131 (1) ◽  
pp. 49-55 ◽  
Author(s):  
Q. Dong ◽  
R. M. Lazarus ◽  
L. S. Wong ◽  
M. Vellios ◽  
D. J. Handelsman
Keyword(s):  
Weight Loss ◽  
Insulin Treatment ◽  
Pulse Generator ◽  
Latin Square ◽  
Pulse Amplitude ◽  
Pulse Frequency ◽  
Metabolic Effect ◽  
Male Rat ◽  
Free Access ◽  
Lh Secretion

ABSTRACT This study aimed to determine the effect of streptozotocin (STZ)-induced diabetes on pulsatile LH secretion in the mature male rat. LH pulse frequency was reduced by 56% and pulse amplitude by 54%, with a consequential decrease of 72% in mean LH levels 8 days after i.v. administration of STZ (55 mg/kg) to castrated Wistar rats compared with castrated non-diabetic controls. Twice daily insulin treatment completely reversed all parameters of pulsatile LH secretion to control values. Food-restricted non-diabetic controls, studied to distinguish the metabolic effect of diabetes from that of concurrent weight loss, demonstrated a 34% reduction in LH pulse frequency but no significant changes in LH pulse amplitude or mean LH levels compared with non-diabetic controls given free access to food. To distinguish whether the decreased LH pulse amplitude in diabetes was due to a reduction in either the quantity of hypothalamic gonadotrophin-releasing hormone (GnRH) released per secretory episode or to decreased pituitary responsiveness to GnRH, the responsiveness of the pituitary to exogenous GnRH (1–1000 ng/kg body weight) was tested in diabetic rats after castration, using a full Latin square experimental design. The net LH response (total area under response curve over 40 min following GnRH) was decreased by 33% (P=0·001) in diabetic compared with control rats. The decreased LH pulse frequency in STZ-induced diabetes therefore suggests that the metabolic effect of diabetes is to decelerate directly the firing rate of the hypothalamic GnRH pulse generator independent of testicular feed-back. These effects were fully reversed by insulin treatment and were only partly due to the associated weight loss. The impaired pituitary responsiveness to GnRH is at least partly involved in the reduction of LH pulse amplitude. Journal of Endocrinology (1991) 131, 49–55

Performance Characterization of a Twin Scroll Volute for Turbocharging Applications

2018 ◽  
Author(s):  
Carlo Cravero ◽  
Mario La Rocca ◽  
Andrea Ottonello
Keyword(s):  
Experimental Data ◽  
Scientific Literature ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
Automatic Design ◽  
Cfd Model ◽  
Radial Turbine ◽  
Wide Range ◽  
Partial Admission

The use of twin scroll volutes in radial turbine for turbocharging applications has several advantages over single passage volute related to the engine matching and to the overall compactness. Twin scroll volutes are of increasing interest in power unit development but the open scientific literature on their performance and modelling is still quite limited. In the present work the performance of a twin scroll volute for a turbocharger radial turbine are investigated in some detail in a wide range of operating conditions at both full and partial admission. A CFD model for the volute have been developed and preliminary validated against experimental data available for the radial turbine. Then the numerical model has been used to generate the database of solutions that have been investigated and used to extract the performance. Different parameters and indices are introduced to describe the volute aerodynamic performance in the wide range of operating conditions chosen. The above parameters can be used for volute development or matching with a given rotor or efficiently implemented in automatic design optimization strategies.

Turbocharger-Design Effects on Gasoline-Engine Performance

2005 ◽  
Vol 127 (3) ◽  
pp. 525-530 ◽  
Author(s):  
Theodosios Korakianitis ◽  
T. Sadoi
Keyword(s):  
Steady Flow ◽  
Mass Flow ◽  
Gasoline Engine ◽  
Pressure Ratio ◽  
Engine Performance ◽  
Thermodynamic Cycle ◽  
Final Choice ◽  
Design Point ◽  
Theoretical Considerations ◽  
Flow Experiments

Specification of a turbocharger for a given engine involves matching the turbocharger performance characteristics with those of the piston engine. Theoretical considerations of matching turbocharger pressure ratio and mass flow with engine mass flow and power permits designers to approach a series of potential turbochargers suitable for the engine. Ultimately, the final choice among several candidate turbochargers is made by tests. In this paper two types of steady-flow experiments are used to match three different turbochargers to an automotive turbocharged-intercooled gasoline engine. The first set of tests measures the steady-flow performance of the compressors and turbines of the three turbochargers. The second set of tests measures the steady-flow design-point and off-design-point engine performance with each turbocharger. The test results show the design-point and off-design-point performance of the overall thermodynamic cycle, and this is used to identify which turbocharger is suitable for different types of engine duties.

scholarly journals Application of Two Shallow Water Models to Steady Flow Analysis in a Vegetated Agricultural Drainage Canal

2013 ◽  
Vol 19 (2) ◽  
pp. 35-41 ◽  
Author(s):  
Hidekazu Yoshioka ◽  
Nobuhiko Kinjo ◽  
Ayaka Wakazono ◽  
Koichi Unami ◽  
Masayuki Fujihara
Keyword(s):  
Shallow Water ◽  
Steady Flow ◽  
Flow Analysis ◽  
Agricultural Drainage ◽  
Drainage Canal ◽  
Shallow Water Models ◽  
Water Models

scholarly journals Correlation of serum androgen and gonadotropin with anti-mullerian hormone in polycystic ovarian syndrome in Eastern Indian population

2019 ◽  
Vol 8 (1) ◽  
pp. 256
Author(s):  
Somnath Singh Raghuvanshi ◽  
Anirban Sinha ◽  
Animesh Maiti ◽  
Partha Pratim Chakraborty ◽  
Asish Kumar Basu ◽  
...  
Keyword(s):  
Polycystic Ovary Syndrome ◽  
Polycystic Ovarian Syndrome ◽  
Pulse Generator ◽  
Polycystic Ovary ◽  
Serum Testosterone ◽  
Pulse Frequency ◽  
Strong Positive Correlation ◽  
Ovary Syndrome ◽  
Cross Sectional ◽  
Ovarian Syndrome

Background: Ovarian steroidogenesis requires gonadotropin stimulation, Luteinizing Hormone (LH) is a key factor in the hyperandrogenaemia of the polycystic ovary syndrome. Progesterone is the primary regulator of Gonadotropin-Releasing Hormone (GnRH) pulse frequency; however, in the polycystic ovary syndrome, the GnRH pulse generator is relatively resistant to the negative feedback effects of progesterone.  Study aims to evaluate the association of Anti-mullerian hormone with serum androgen and gonadotropin level in adolescents and young women of Polycystic Ovary Syndrome (PCOS).Methods: This was a single centre observational Cross-sectional study carried out in the department of Endocrinology and metabolism, Medical College, Kolkata from March 2017 to January 2019. Total number of study subjects were 207 out of which 138 were cases.Results: The AMH had strong positive correlation with serum testosterone in both case and control groups (r 0.542, p<0.001 and r 0.57, p<0.001) respectively .After the adjustment of age and BMI , the AMH moderately positive  but extremely significant correlation with serum testosterone as compare to control.Conclusions: Hyperandrogenaemia and higher ratio of LH and FSH associated with higher serum AMH level is associated with the higher serum AMH in polycystic ovarian syndrome.

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