Reduction of the erosive effects of effluent jets from spillways by contractions in the flow

Lara, Rafael de; Ota, José Junji; Fabiani, André Luiz Tonso

doi:10.1590/2318-0331.0318170154

Rafael de Lara

Universidade Federal do Paraná, Curitiba, PR, Brasil

José Junji Ota

Universidade Federal do Paraná, Curitiba, PR, Brasil

André Luiz Tonso Fabiani

Universidade Federal do Paraná, Curitiba, PR, Brasil

E-mails: rafael.lara@copel.com (RL), ota.dhs@ufpr.br (JJO), andre.dhs@ufpr.br (ALTF)

Authors contributions Rafael de Lara: data collection, data analysis, article elaboration.

André Luiz Fabiani: coordination of physical model tests, data analysis, article revision.

José Junji Ota: main analysis and conclusions of the research, article elaboration and revision.

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Figure 1
Slit Bucket at Geheyan Dam in China. Source: China Gezhouba Group International Engineering Co. Ltd (2010) CHINA GEZHOUBA GROUP INTERNATIONAL ENGINEERING CO. LTD. Slit Bucket at Geheyan Dam in China. China, 2010. Available from: <HTTP://www.gzbgj.com/english/article.asp?id=471>. Access on: 22 June 2010.
<HTTP://www.gzbgj.com/english/article.a... .

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Figure 2
Sketch and typical section of Slit Bucket.

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Figure 3
Outlet of the Dong Feng dam. Source: Gao, Liu and Guo (2000) GAO, J.; LIU, Z.; GUO, J. Energy dissipation for high dams: large dams in China – a fifty year review. Beijing: Chinese National Committee on Large Dams, 2000. .

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Figure 4
Scheme and typical sections of Flaring Pier.

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Figure 5
Dachaoshan spillway. Source: MD&A (2018) MD&A – MALCOLM DUNSTAN & ASSOCIATES. Devon, 2018. Available from: <http://www.rccdams.co.uk/dams/dachaoshan/>. Access on: 20 Mar. 2018.
http://www.rccdams.co.uk/dams/dachaosha... .

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Figure 6
Pilot hydraulic model used in tests – original configuration.

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Figure 7
Aspect of effluent jet from Slit Buckets.

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Figure 8
Data of the Slit Bucket tests plotted with the Yarnell equations.

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Figure 9
“Y” shaped Slit Bucket structure (Alternative 7).

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Figure 10
Flaring Piers used in the tests.

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Figure 11
Test performed with Flaring Piers (Alternative 9) for flow with a 100-year recurrence.

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Figure 12
Data of the Alternatives tested with Flaring Piers in relation to the Yarnell equations.

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Figure 13
Results with Slit Buckets (Alternatives 3 and 4) and with conventional spillway (Alternative 2) for Tr=5.

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Figure 14
Results with Slit Buckets (Alternatives 3 and 4) and with conventional spillway (Alternative 2) for Tr=10,000.

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Figure 15
Scour hole formed in the test of Alternative 3 for a flow with a 5-year recurrence.

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Figure 16
Coefficient “c” and the contraction ratio “η” for the Alternatives with Slit Buckets.

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Figure 17
Coefficient “c” and the angle of deflection “θ” for alternatives with Slit Buckets.

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Figure 18
Results with Flaring Piers (Alternatives 8 and 9) and with conventional spillway (Alternative 1) for Tr=5.

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Figure 19
Results with Flaring Piers (Alternatives 8 and 9) and with conventional spillway (Alternative 1) for Tr=10,000.

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Figure 20
Coefficient “c” and the contraction ratio “η” for the Alternatives with Flaring Piers.

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Figure 21
Coefficient “c” and the angle of deflection “θ” for Alternatives with Flaring Piers.

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Figure 22
Comparison of the total volume of eroded material after test with 10,000 year flow.

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Figure 23
General aspect of erosion in Alternative 9, after test with 100-year flow.

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Table 1
Chinese Dams with Flaring Piers and Slit Buckets.

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Table 2
Structures Tested.

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Table 3
Summary of the hydraulic behavior of the Slit Bucket tests.

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Table 4
Summary of the hydraulic behavior of the Flaring Pier tests.

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Table 5
Characteristics of the tests with Slit Buckets compared to the conventional spillway with distinct chutes.

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Table 6
Characteristics of the tests with Flaring Piers compared to the conventional single chute spillway.

(1)

(2)

(3)

(4)

(5)

(6)

Project	Type of Dam	Hb (m)	Hd (m)	Design Flow (m³/s)	Type of dissipation
Flaring Piers
Geheyan	Gravity Concrete	151	-	17,060	Launching in plunge pool
Ankang	Gravity Concrete	128	-	37,000	Stilling basin
Dachaoshan	Roller Compacted Concrete	115	-	23,800	Stepped chute and stilling basin
Wuqiangxi	Gravity Concrete	84.5	-	55,962	Stilling basin
Yantan	Gravity Concrete	76	60.40	32,760	Stilling basin
Shuidong	Roller Compacted Concrete	57	-	8,232	Stepped chute and stilling basin
Slit Buckets
Shuibuya	Concrete Face Rockfill	234	171.00	15,243	Ski jump
Hongjiadu	-	182	-	6,996	Ski jump
Longyangxia	Gravity Concrete Arch	178	-	2,247 ^* * total flow through one gate. Source: Elaborated with data from Gao, Liu and Guo (2000) .	Ski jump
Dongfeng	Concrete Arch	162	77.78	1,080 ^* * total flow through one gate. Source: Elaborated with data from Gao, Liu and Guo (2000) .	Direct launching in plunge pool
Dongjiang	Concrete Arch	157	99.25	1,450 ^* * total flow through one gate. Source: Elaborated with data from Gao, Liu and Guo (2000) .	Skijump
Lijiaxia	Concrete Arch	155	113	2,155 ^* * total flow through one gate. Source: Elaborated with data from Gao, Liu and Guo (2000) .	Direct launching in plunge pool
Geheyan	Gravity Concrete Arch	151	77.1	1,013 ^* * total flow through one gate. Source: Elaborated with data from Gao, Liu and Guo (2000) .	Launching in plunge pool
Xibeikou	-	95	78.89	2,233 ^* * total flow through one gate. Source: Elaborated with data from Gao, Liu and Guo (2000) .	Ski jump
Nanyi	Gravity Concrete	-	-	-	Surface spillway

Name of alternative	Type of structure	Contraction Ratio “η”	Angle of deflection “θ”	Chute	Shape of cross-section
Alternative 1	Conventional Ski Jump	0	0	Single	rectangular
Alternative 2	Conventional Ski Jump	0	0	Divided	rectangular
Alternative 3*	Ski Jump with Slit Bucket	0.50	14.3	Divided	rectangular
Alternative 4*		0.33	18.9	Divided	rectangular
Alternative 5*		0.16	23.2	Divided	rectangular
Alternative 6		0.33	10.1	Divided	rectangular
Alternative 7		0.25	11.2	Divided	in “Y”
Alternative 8	Ski Jump with Flaring Piers	0.70	15.0	Single	rectangular
Alternative 9	Ski Jump with Flaring Piers	0.50	19.0	Single	rectangular

Structure	Tr (years)	5	25	100	10,000
Structure	Q (m³/s)	2,070	3,371	4,491	7,713
Conventional	Alternative 2 η=1.00 θ=0 Individual chutes	Adequate	Adequate	Adequate	Adequate
Slit Buckets	Alternative 3 η=0.50 θ=14.3º	Adequate	Adequate	Shock of standing waves at the limit of the structure	Flow overtops the deflectors
	Alternative 4 η=0.33 θ=18.9º	Shock of standing waves within the structure Vertical “rooster tails”	Shock of standing waves within the structure Vertical “rooster tails”	Shock of standing waves within the structure Vertical “rooster tails” Flow overtops the deflectors	Flows overtop the deflectors Jets unite
	Alternative 5 η=0.16 θ=23.2º	Occurrence of drowning Flow overtops the deflectors	Occurrence of drowning Flow overtops the deflectors	Occurrence of drowning Flow overtops the deflectors Jets with a vertical tendency	Flow overtops the deflectors Jets unite
	Alternative 6 η=0.33 θ=10.1º	Shock of standing waves within the structure	Shock of standing waves within the structure	Shock of standing waves within the structure	Shock of standing waves within the structure “Rooster tails” hit the structure
	Alternative 7 η=0.25 θ=11.2º “Y”	Shock of standing waves within the structure Slender jets	Shock of standing waves within the structure Slender jets Clash of the “rooster tails” with the structure	Very slender water jets Intense shock of “rooster tails” against the structure	Very slender water jets Intense shock of the “rooster tails” against the structure Water overflow “glues” to the superior part of the slit

Structure	Tr (years)	5	25	100	10.000
Structure	Q (m³/s)	2,070	3,371	4,491	7,713
Conventional	Alt. 1 η=1.00 θ=0 Single chute	Adequate	Adequate	Adequate	Unstable “Rooster tails”
Flaring Piers	Alt. 8 η=0.70 θ=15.0º	Adequate lateral nappe	Steep jets Lateral nappe	Steep “Rooster tails” Flow overtopping the walls Lateral nappe	Extremely steep “Rooster tails” Flow overtopping the walls Very large lateral nappe Extreme instability
Flaring Piers	Alt. 9 η=0.50 θ=19.0º	Adequate lateral nappe	Adequate lateral nappe	Flow overtopping the walls	Flow overtopping the walls Very unstable “Rooster tails” Spray/Instability Overtopping the walls

Tr (years)	Q (m³/s)	q (m³/s/m)	N.A.R. (m)	N.A.J. (m)	Minimum scour elevation (m)	H (m)	Froude Nº	q^0.54xH^0.225	D (m)			c
Tr (years)	Q (m³/s)	q (m³/s/m)	N.A.R. (m)	N.A.J. (m)	Minimum scour elevation (m)	H (m)	Froude Nº	q^0.54xH^0.225	Measured	Veronese	CBDB	c
(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)	(11)	(12)	(13)
Alternative 2
5	2,070	35.9	635.00	568.67	547	66.33	7.3	17.78	21.67	33.78	21.33	1.177
25	3,371	58.5	635.00	569.34	539	65.66	5.8	23.08	30.34	43.85	27.70	1.287
100	4,491	78.0	635.00	570.28	534	64.72	5.0	26.86	36.28	51.04	32.23	1.287
10,000	7,173	124.5	636.50	572.03	524	64.48	4.0	34.56	48.03	65.66	41.47	1.355
Alternative 3
5	2,070	35.9	635.00	568.67	550	66.33	7.3	17.78	18.67	33.78	21.33	1.073
25	3,371	58.5	635.00	569.34	541	65.66	5.8	23.08	28.34	43.85	27.70	1.245
100	4,491	78.0	635.00	570.28	536	64.72	5.0	26.86	34.28	51.04	32.23	1.271
10,000	7,173	124.5	636.50	571.51	526	64.99	4.0	34.62	45.51	65.78	41.55	1.271
Alternative 4
5	2,070	35.9	635.00	568.62	551	66.38	7.3	17.78	17.62	33.78	21.34	0.972
25	3,371	58.5	635.00	569.80	545	65.20	5.8	23.04	24.80	43.78	27.65	1.085
100	4,491	78.0	635.00	570.32	541	64.68	5.0	26.86	29.32	51.03	32.23	1.107
10,000	7,173	124.5	636.50	572.33	529	64.17	4.0	34.52	43.33	65.59	41.43	1.261
Alternative 5
5	2,070	35.9	635.00	568.57	555	66.43	7.3	17.78	13.57	33.79	21.34	0.766
25	3,371	58.5	635.00	569.70	551	65.30	5.8	23.05	18.70	43.80	27.66	0.816
100	4,491	78.0	635.00	570.73	543	64.28	5.0	26.82	27.73	50.96	32.18	1.045
10,000	7,173	124.5	636.50	572.00	527	64.51	4.0	34.56	45.00	65.67	41.48	1.299
Alternative 6
5	2,070	35.9	635.00	568.57	547	66.43	7.3	17.78	21.57	33.79	21.34	1.201
25	3,371	58.5	635.00	569.55	540	65.45	5.8	23.06	29.55	43.82	27.68	1.316
100	4,491	78.0	635.00	569.73	535	65.28	5.0	26.91	34.73	51.13	32.30	1.316
10,000	7,173	124.5	636.50	572.94	526	63.57	4.0	34.45	46.93	65.45	41.34	1.400
Alternative 7
5	2,070	35.9	635.00	568.69	548	66.31	7.3	17.78	20.69	33.78	21.33	1.198
25	3,371	58.5	635.00	570.34	541	64.66	5.8	23.00	29.34	43.70	27.60	1.263
100	4,491	78.0	635.00	569.73	537	65.27	5.0	26.91	32.73	51.13	32.29	1.201
10.000	7,173	124.5	636.50	571.99	525	64.52	4.0	34.56	46.99	65.67	41.48	1.365

Tr (years)	Q (m³/s)	q (m³/s/m)	N.A.R. (m)	N.A.J. (m)	Minimum scour elevation (m)	H (m)	Froude Nº	q^0.54xH^0.225	D (m)			c
Tr (years)	Q (m³/s)	q (m³/s/m)	N.A.R. (m)	N.A.J. (m)	Minimum scour elevation (m)	H (m)	Froude Nº	q^0.54xH^0.225	Measured	Veronese	CBDB	c
(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)	(11)	(12)	(13)
Alternative 1
5	2,070	35.9	635.00	570.06	547	64.95	6.4	17.69	23.05	33.62	21.23	1.303
25	3,371	58.5	635.00	572.92	537	62.09	5.0	22.79	35.92	43.30	27.35	1.519
100	4,491	78.0	635.00	574.72	532	60.28	4.3	26.43	42.72	50.23	31.72	1.605
10,000	7,173	124.5	636.50	575.29	518	61.21	3.4	34.16	57.29	64.90	40.99	1.677
Alternative 8
5	2,070	35.9	635.00	570.49	550	64.84	6.4	17.69	20.49	33.61	21.22	1.181
25	3,371	58.5	635.00	571.68	547	63.26	5.0	22.89	24.68	43.49	27.47	1.065
100	4,491	78.0	635.00	572.92	544	62.09	4.3	26.61	28.92	50.56	31.93	1.091
10,000	7,173	124.5	636.50	574.48	537	61.45	3.4	34.19	37.48	64.96	41.03	1.102
Alternative 9
5	2,070	35.9	635.00	570.16	552	64.84	6.4	17.69	18.16	33.61	21.22	1.027
25	3,371	58.5	635.00	571.74	548	63.26	5.0	22.89	23.74	43.49	27.47	1.033
100	4,491	78.0	635.00	572.91	545	62.09	4.3	26.61	27.91	50.56	31.93	1.045
10,000	7,173	124.5	636.50	575.05	541	61.45	3.4	34.19	34.05	64.96	41.03	1.005

[1] E-mails: rafael.lara@copel.com (RL), ota.dhs@ufpr.br (JJO), andre.dhs@ufpr.br (ALTF)

Brasil

Brasil

Reduction of the erosive effects of effluent jets from spillways by contractions in the flow

Redução dos efeitos erosivos de jatos efluentes de vertedouros através de contrações no escoamento

ABSTRACT